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

Light and ultrastructural features of a cerebellar hemangioblastoma in a 56-year-old man are described in detail. The neoplasm was composed of three major cell types: endothelial cells, pericytes, and stromal cells. The endothelial cells lined the fenestrated vascular channels. The pericytes were ensheathed by their own basal lamina which separated them from the basal lamina covering the endothelium. The stromal cells contained, in addition to the conventional organelles, numerous membrane-bound lipid inclusions, annulate lamellae, and nuclear bodies. There were also present transitional cells which shared the fine structure of all the three major cell types. Histogenetically, the tumor was considered to be of vascular origin. The stromal cells represented the stem cells which, under the neoplastic influence, continued to proliferate and differentiate into "vasoformative" elements (pericytes and endothelium) which formed new blood vessels. The transitional forms between the stromal cells and the "vasoformative" elements suggested that the cellular components of a hemangioblastoma shared a common ancestry, most likely of an angioblastic lineage.
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PMID:Ultrastructure of cerebellar hemangioblastoma. 36 Dec 12

Neither immunologic nor genetic concepts of carcinogenesis have yet been decisively confirmed, and epigenetic theories, as formulated so far, are either non-predictive or insufficiently consistent with morphologic and experimental evidence. Computing data, concerned with carcinogenic mechanisms and neoplastic changes at the level of the endoplasmic reticulum, may lead to a new coherent understanding of tumor pathogenesis. Carcinogenic agents initiate biophysical perturbations, chemical alterations and conformational transitions in the membrane lattice of the endoplasmic reticulum. Foremost among the resulting neoplastic changes is an increased, irreversible separation of polyribosomes from membranes of the ergastoplasm. The carcinogenic process, apparently, deletes a protein required for polysome attachment. Since microsomal cytochromes can be synthesized by membrane-bound polysomes only, the translation of genetic information for their biosynthesis is irreversibly restricted. A similar, self-perpetuating deficiency may be postulated for the polysome attachment protein. Activities, depending on cytochromes P-450 and b5, are hampered, e.g. those of the monoxygenase system. Cholesterogenesis is derepressed. Ratios of phospholipids/cholesterol are decreased, and lipid-protein complexes, altered both in structure and function. Another distinct effect of the membrane-polysome separation is the unmasking of thiol-disulfide exchange enzymes which, in turn, stimulate the biosyntehsis of proteins and of deoxyribonucleotides involved in cell replication.
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PMID:Microsomal aspects of carcinogenesis and neoplasia. 37 54

The clinical, histological, and ultrastructural aspects of a cervical paraganglioma of the vagus nerve, in a 66-year-old white man, have been discussed in detail. Ultrastructurally, the tumor chief cells contained characteristic membrane-bound and dense-cored neurosecretory granules which ranged in size from 85 millimicron to 190 millimicron. Unlike earlier ultrastructural reports, the present study showed the presence of sustentacular or supporting cells. These cells were smaller, darker, polymorphic, and were commonly located at the periphery of a single or group of chief cells. Furthermore, unlike earlier reports on vagal paragangliomas, nonmyelinated nerve fibers and an occasional axon were identified in the present fine structure study.
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PMID:A nonfunctioning paraganglioma of vagus nerve: an ultrastructural study. 44 60

Spontaneous tumors in urodele amphibians have been considered uncommon, and this resistance has sometimes been associated with the natural regenerative capacity of tissues in such species. This report describes spontaneous, nonpigmented, benign epitheliomas which were found in 44 of 1586 (2.8%) adult newts, Cynops pyrrhogaster, captured in central Japan. Both sexes were affected equally, usually with single tumors occurring at any epidermal site. Under laboratory conditions, these large tumors rapidly regressed or disappeared. Lesions were histologically noninvasive, hyperplastic epidermal reactions accompanied by loss of basal, subdermal melanocytes. Ultrastructurally, enlargement of intercellular spaces between tumor cells, increased pigment granules and membrane-bound cytoplasmic aggregates within the spaces, swollen rough endoplasmic reticula, degenerating pigment granules, and altered corneal cells were noted. Virus-like particles were observed in one tumor cell. Prelminary attempts failed to demonstrate transmissibility of the tumor, and no new cases arose under laboratory conditions. The cause of these tumors in the Japanese newt remains unknown, and it is suggested that if a viral agent is involved then other environmental cofactors (diet, temperature, or water constituents) are required for its expression.
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PMID:Spontaneous regressive epitheliomas in the Japanese newt, Cynops pyrrhogaster. 44 90

The outer medullary (juxtacortical) zone of a normal equine adrenal gland had columnar chromaffin-positive cells arranged with their long axes perpendicular to fine vascular channels. The deeper medullary regions were composed of smaller irregularly round to polygonal chromaffin positive cells in small packets. Both cell types contained two types of membrane-bound cytoplasmic secretory granules. Osmiophilic granules with a homogeneous core, crenated membrane and narrow submembranous halo predominated in the columnar juxtacortical cells. The rounder, central medullary cells contained predominantly electron dense granules with a wide irregular electron lucent space between an eccentric core and the granule membrane. In contrast, irrespective of cell type or zone, cells from a pheochromocytoma contained only one type of granule similar to that described for the juxtacortical region of the normal equine adrenal medulla. The tumor cells could be classified into three subtypes based on density of granule packing but the granules were morphologically similar in all tumor cells.
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PMID:A light and electron microscopic study of a normal adrenal medulla and a pheochromocytoma from a horse. 45 13

The histologic features of aortic body neoplasia, hyperplasia, and normal aortico-pulmonary paraganglia were described for a series of 56 rats of several strains. Argyrophilic cytoplasmic granules were demonstrated in chief cells of the aortic body lesions, and electron microscopic examination disclosed the presence of electron-dense, membrane-bound granules in these cells. In a series of ageing rats, hyperplasia and neoplasia of the aortico-pulmonary paraganglia occurred more frequently in female WAG/Rij rats than in males of that strain, and more frequently than in males and females of the BN/Bi strain or of the (WAG X BN)F1 hybrid. No apparent causal relationship to chronic hypoxia could be shown, in that no correlation between the development of aortic body neoplasia or hyperplasia and cardiopulmonary disease was found. Aortic body lesions did not appear to occur as part of a multiple endocrinopathy syndrome, although hyperplasia and neoplasia of various endocrine organs occurred relatively frequently in the WAG/Rij strain.
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PMID:Aortic body tumours and hyperplasia in the rat. 46 58

This study was undertaken to examine the mechanism by which metabolic inhibition reduces amino acid active transport in ehrlich ascites tumor cells. At 37 degrees C the metabolic inhibitor combination 0.1 mM 2,4-dinitrophenol (DNP) + 10 mM 2- deoxy-D-glucose (DOG) reduced the cell ATP concentration to 0.10- 0.15 mM in less than 5 min. This inhibition was associated with a 20.6 percent +/- 6.4 percent (SD) decrease in the initial influx of alpha-aminoisobutyric acid (AIB), and a two- to fourfold increase in the unidirectional efflux. These effects could be dissociated from changes in cell Na(+) or K(+) concentrations. Cells incubated to the steady state in 1.0-1.5 mM AIB showed an increased steady-state flux in the presence of DNP + DOG. Steady- state fluxes were consistent with trans-inhibition of AIB influx and trans-stimulation of efflux in control cells, but trans- stimulation of both fluxes in inhibited cells. In spite of the reduction of the cell ATP concentration to less than 0.15 mM and greatly reduced transmembrane concentration gradients of Na(+) and K(+), cells incubated to the steady state in the presence of the inhibitors still established an AIB distribution ration 13.8 +/- 2.6. The results are interpreted to indicate that a component of the reduction of AIB transport produced by metabolic inhibition is attributable to other actions in addition to the reduction of cation concentration gradients. Reduction of cell ATP alone is not responsible for the effects of metabolic inhibition, and both the transmembrane voltage and direct coupling to substrate oxidation via plasma-membrane-bound enzymes must be considered as possible energy sources for amino acid active transport.
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PMID:A reassessment of decreased amino acid accumulation by Ehrlich ascites tumor cells in the presence of metabolic inhibitors. 56 Nov 60

Clinically noninvolved skin of 5 patients with metastasizing malignant melanoma (MM) has been investigated under the electron microscope before and 4 weeks after repeated BCG inoculations (4 X). Increased melanin content, giant and unusual melanosomes, signs of cellular activity and some degenerative changes of the melanocytes were observed both in nontreated and in treated patients. Langerhans cells were markedly stimulated containing melanosome complexes and membrane-bound inclusions of different size and shape. Presence of amyloid, macrophage and plasma cells were also observed prior to and after repeated BCG inoculation, however, cellular infiltration was increased after this treatment and several dermal Langerhans cells appeared. These observations suggest that alterations of the melanocytes occur in MM, which are not confined to the tumor area. Moreover, BCG treatment seems to stimulate the tissue reaction against the tumor, including the activity of Langerhans cells.
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PMID:Alterations of the clinically noninvolved skin in patients with malignant melanoma. An electron microscopic study before and after repeated application of BCG. 62 28

Taking into account the conception of metabolic immunosuppression, arising in the case when fatty acids but no glucose serves as the basic energetic substrate, the authors have studied the effect of miscleron (clofibrate, athromid-S) on a number of hormonal-metabolic and immune indices. It is shown that miscleron in addition to decreasing the blood level of cholesterol, beta-lipoproteids, triglycerids, free fatty acids, cortisol and reducing 17-ketosteroids excretion, produces higher indices of the blasttransformation reaction, induced by FHA, an increased phagocytic index of monocytes, a rise in the level of peroxidase and lysosomal activity of monocytes. Miscleron and other substances lowering the lipid level in blood should be examined in patients with nonlymphoid types of tumors both with the aim to eliminate metabolic immunosuppression and to retard the rate of tumor cells growth due to a reduced level of low density lipoproteins.
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PMID:[Improvement in the functional and morphological mononuclear blood cell indices under the influence of miscleron]. 65 76

This report documents a case of a fatal primary malignant neoplasm of the liver with metastases to the lymph nodes of the porta hepatis and the pubic bone. Profound, intractable hypoglycemia was seen during the course of the disease. No immunoassayable insulin was found in the blood during episodes of severe, symptomatic hypoglycemia. The neoplasm was composed of uniform polygonal cells with distinct cytoplasmic borders growing in broad strands with a tendency toward nesting and was morphologically similar to neoplasms of neural crest derivation. The presence of osmophilic, membrane-bound granules in the neoplastic cells was documented by ultrastructural studies. The tentative conclusion that the hypoglycemia was produced by the secretion of a substance with insulin-like activity, probably a polypeptide, by the secretory granules in the neoplastic cells is supported by clinical and laboratory data.
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PMID:Malignant apudoma of the liver with symptomatic intractable hypoglycemia. 67 61


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