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

The following is a statistical report regarding gastric polyps:Frequency determined through endoscopic examinations was 3.6%. The terms hyperplastic polyps and adenomas were used for the classification of epithelial polyps, considering the suprafoveal hyperplasias within the hyperplastic polyps, provided they were elevated lesions. Out of 2,283 polyps, 1,959 were hyperplastic (86%) and 324 were adenomas (14%). When analyzing 780 polyps, 86 (11%) were found to have the Nakamura III category. With regard to topography, in an examination of 2253 polyps, hyperplastic polyps were located as follows: 325 (17%) in the antrum, 1402 (73%) in the body and 202 (10%) in the fundus. Adenomas had a different distribution: 212 (65%) in the antrum, 100 (31%) in the body and 12 (4%) in the fundus. Out of 371 hyperplastic polyps examined, 49% were pediculate and 51% were sessile; on the contrary, 86 % of adenomas were sessile. The average age was 66.2 years in adenoma carriers, 58.5 in those having hyperplastic polyps, and 57.4 for suprafoveal hyperplasias. In 287 adenomas, 94.1% of carriers were over 40 years old. Out of 92 adenomas examined, 21.7% evidenced adenoma metaplasia and 72.8% evidenced metaplasia in adjacent areas. Only 5.5% had no metaplasia. In 105 hyperplastic polyps studied, intestinal metaplasia was found: 16.7% in the polyp and 60% in adjacent areas. No metaplasia was found in the remaining 23.3%. Average size of the adenomas was 14 mm and of hyperplastic polyps, 11 mm. A total of 195 adenomas were smaller than 10 mm. The percentage of malignization in 288 adenomas examined was closely related to their size: 214 (66%) smaller than 20 mm, had a malignization percentage of 7%; 74 (34%) larger than 20 mm, had 51% malignization, and 86.2% malignization was found in adenomas of over 40 mm.Global malignization percentage of adenomas was 18%. However, when adenomas with high grade dysplasia in the 4.1 category of the Viena classification (non-invasive high grade neoplasia) were considered, this percentage rose to 26%. Malignization of hyperplastic polyps was 0.8%. When gastric acidity was determined using the maximum stimulation method, out of 77 cases of patients with hyperplastic polyps, 55 (60%) had real achlorhydria, 10 (18%) hypochlorhydria, 11 (20%) normochlorhydria, and only 1 (4) hyperchlorhydria. D.A.B. was 1.97 mEql for hyperplastics and 1.60 mEql for adenomas. D.A.M. was 6.05 mEql for hyperplastics and 5.49 mEql for adenomas. Our experience as to normal cases showed 2.5 mEqh +/- 1.2 and 22 mEqh +/- 6, respectively, for D.A.B and D.A.M.
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PMID:[Gastric epithelial polyps (first part)]. 1471 23

Cancer cells invade by secreting degradative enzymes, which are sequestered in lysosomal vesicles. In this study, the impact of an acidic extracellular environment on lysosome size, number, and distance from the nucleus in human mammary epithelial cells (HMECs) and breast cancer cells of different degrees of malignancy was characterized because the physiological microenvironment of tumors is frequently characterized by extracellular acidity. An acidic extracellular pH (pH(e)) resulted in a distinct shift of lysosomes from the perinuclear region to the cell periphery irrespective of the HMECs' degree of malignancy. With decreasing pH, larger lysosomal vesicles were observed more frequently in highly metastatic breast cancer cells, whereas smaller lysosomes were observed in poorly metastatic breast cancer cells and HMECs. The number of lysosomes decreased with acidic pH values. The displacement of lysosomes to the cell periphery driven by extracellular acidosis may facilitate exocytosis of these lysosomes and increase secretion of degradative enzymes. Filopodia formations, which were observed more frequently in highly metastatic breast cancer cells maintained at acidic pH(e), may also contribute to invasion.
Neoplasia
PMID:Extracellular acidification alters lysosomal trafficking in human breast cancer cells. 1496 46

Vacuolar-type H+-adenosine triphosphatase (V-ATPase) is one of the most fundamental enzymes in nature. V-ATPases are responsible for the regulation of proton concentration in the intracellular acidic compartments. It has similar structure with the mitochondrial F0F1-ATP synthase (F-ATPase). dagger The V-ATPases are composed of multiple subunits and have various physiological functions, including membrane and organelle protein sorting, neurotransmitter uptake, cellular degradative processes, and cytosolic pH regulation. The V-ATPases have been involved in multidrug resistance. Recently, plasma membrane V-ATPases have been involved in regulation of extracellular acidity, essential for cellular invasiveness and proliferation in tumor metastasis. The current knowledge regarding the structure and function of V-ATPase and its role in cancer biology is discussed.
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PMID:Plasmalemmal vacuolar-type H+-ATPase in cancer biology. 1505 22

The following is a statistical report regarding gastric polyps: Frequency determined through endoscopic examinations was 3.6%. The terms hyperplastic polyps and adenomas were used for the classification of epithelial polyps, considering the suprafoveal hyperplasias within the hyperplastic polyps, provided they were elevated lesions. Out of 2,283 polyps, 1,959 were hyperplastic (86%) and 324 were adenomas (14%). When analyzing 780 polyps, 86 (11%) were found to have the Nakamura III category. With regard to topography, in an examination of 2253 polyps, hyperplastic polyps were located as follows: 325 (17%) in the antrum, 1402 (73%) in the body and 202 (10%) in the fundus. Adenomas had a different distribution: 212 (65%) in the antrum, 100 (31%) in the body and 12 (4%) in the fundus. Out of 371 hyperplastic polyps examined, 49% were pediculate and 51% were sessile; on the contrary, 86 % of adenomas were sessile. The average age was 66.2 years in adenoma carriers, 58.5 in those having hyperplastic polyps, and 57.4 for suprafoveal hyperplasias. In 287 adenomas, 94.1% of carriers were over 40 years old. Out of 92 adenomas examined, 21.7% evidenced adenoma metaplasia and 72.8% evidenced metaplasia in adjacent areas. Only 5.5% had no metaplasia. In 105 hyperplastic polyps studied, intestinal metaplasia was found: 16.7% in the polyp and 60% in adjacent areas. No metaplasia was found in the remaining 23.3%. Average size of the adenomas was 14 mm and of hyperplastic polyps, 11 mm. A total of 195 adenomas were smaller than 10 mm. The percentage of malignization in 288 adenomas examined was closely related to their size: 214 (66%) smaller than 20 mm, had a malignization percentage of 7%; 74 (34%) larger than 20 mm, had 51% malignization, and 86.2% malignization was found in adenomas of over 40 mm. Global malignization percentage of adenomas was 18%. However, when adenomas with high grade dysplasia in the 4.1 category of the Viena classification (non-invasive high grade neoplasia) were considered, this percentage rose to 26%. Malignization of hyperplastic polyps was 0.8%. When gastric acidity was determined using the maximum stimulation method, out of 77 cases of patients with hyperplastic polyps, 55 (60%) had real achlorhydria, 10 (18%) hypochlorhydria, 11 (20%) normochlorhydria, and only 1 (4) hyperchlorhydria. D.A.B. was 1.97 mEql for hyperplastics and 1.60 mEql for adenomas. D.A.M. was 6.05 mEql for hyperplastics and 5.49 mEql for adenomas. Our experience as to normal cases showed 2.5 mEqh +/- 1.2 and 22 mEqh +/- 6, respectively, for D.A.B and D.A.M.
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PMID:[Gastric epithelial polyps (part two)]. 1509 42

Sialic acids are monosaccharides with relatively strong acidity which belong to the most important molecules of higher animals and also occur in some microorganisms. They are bound to complex carbohydrates and occupy prominent positions, especially in cell membranes. Their structural diversity is high and, correspondingly, the mechanisms for their biosynthesis complex. Sialic acids are involved in a great number of cell functions. Due to their cell surface location these acidic molecules shield macromolecules and cells from enzymatic and immunological attacks and thus contribute to innate immunity. In contrast to this masking role, enabling, for example, blood cells and serum glycoproteins a longer life-time, sialic acids also represent recognition sites for various physiological receptors, such as the selectins and siglecs, as well as for toxins and microorganisms and thus allow their colonization. The recognition function of sialic acids can again be masked by O-acetylation, which modifies the interaction with receptors. Many viruses use sialic acids for the infection of cells. As sialic acids play also a decisive role in tumor biology, they prove to be rather versatile molecules that modulate biological and pathological cellular events in a sensitive way. Thus, they are most prominent representatives of mediators of molecular and cellular recognition.
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PMID:Victor Ginsburg's influence on my research of the role of sialic acids in biological recognition. 1515 63

The microenvironmental pH and oxygenation is known to influence tumor cell response to heat, radiation, photodynamic and even chemotherapy. We have studied the previously untested influence of acidity and hypoxia on tumor and endothelial cell sensitivity to freezing. In addition, we have measured changes in oxygenation in vivo in murine FSaII fibrosarcomas after freeze injury. A low pH or low oxygenation environment was found to increase the sensitivity of tumor and endothelial cells to freezing at -20 degrees C or -40 degrees C in vitro. However, low pH and low oxygenation combined did not further increase cryosensitivity of the cells. In vivo, tumor oxygenation after freeze injury was studied immediately or 1-3 days after a standard freezing protocol was applied to FSaII tumors ranging from 250-500 mm3 grown in the rear-limb of C3H mice. Tumor oxygenation at the edge of the iceball was found to transiently increase 1-2 hours after freezing. At 1-3 days after freezing, a treatment that delayed FSaII tumor growth by approximately 1.5-fold, the mean tumor oxygenation was significantly increased by up to 2.5-fold from a control level of 5 mmHg partial pressure of oxygen (pO2), especially at the periphery of the tumor. We conclude that manipulation of pH or oxygenation has potential to increase the anti-tumor effects of minimally invasive cryosurgical techniques. Furthermore, the dynamic changes in oxygenation after freeze injury in vivo suggests value in combining cryotherapy with treatments dependent on oxygenation levels. Ultimately, these may be routes to more reliable treatment response with fewer recurrences.
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PMID:Assessing pH and oxygenation in cryotherapy-induced cytotoxicity and tissue response to freezing. 1516 17

Tumour angiogenesis is triggered by various signals characteristic of the tumour microenvironment, including low oxygen tension, low extracellular pH and low glucose concentration. Tumour microvasculature is chaotic, producing perfusion heterogeneities which can be visualized by MRI and other modalities. Inefficient perfusion in tumours produces regions of transient and chronic hypoxia. Tumour hypoxia is associated with adverse clinical outcomes and reduced patient survival. Hypoxia may be a factor in activation of extracellular matrix-degrading proteases, and some studies have correlated primary tumour hypoxia with likelihood of tumour cell dissemination. Exposure to hypoxia either induces or selects for cells that are hyperglycolytic, and this in turn produces local acidosis which is also a common feature of solid tumours. Increased glucose uptake in hyperglycolyzing tumour cells is the basis of lesion-visualization in positron emission tomography using 18F-fluorodeoxyglucose. Tumour acidity can reduce the effectiveness of weak-base drugs, but can be exploited to increase the anti-tumour activity of weak-acid chemotherapeutics. Evidence linking tumour acidity with increased activity of several extracellular matrix-degrading enzyme systems is examined. High levels of lactate, another end-product of glycolysis, in primary lesions have been correlated with increased likelihood of metastasis. In the numerous studies correlating hypoxia, acidity and lactate with metastasis, the direction of the causality has not been adequately established. We hypothesize that adoption of a hyperglycolytic phenotype is a necessary feature of carcinogenesis itself, and confers a survival and proliferative advantage to tumour cells over surrounding normal cells. Empirical evidence supporting this "acid-mediated tumour invasion" model is discussed.
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PMID:Microenvironmental and cellular consequences of altered blood flow in tumours. 1545 10

Acidic extracellular pH (pHe) is a typical attribute of a tumor microenvironment, which has an impact on cancer development and treatment outcome. It was believed to result from an accumulation of lactic acid excessively produced by glycolysis. However, metabolic profiles of glycolysis-impaired tumors have revealed that CO2 is a significant source of acidity, thereby indicating a contribution of carbonic anhydrase (CA). The tumor-associated CA IX isoform is the best candidate, because its extracellular enzyme domain is highly active, expression is induced by hypoxia and correlates with poor prognosis. This study provides the first evidence for the role of CA IX in the control of pHe. We show that CA IX can acidify the pH of the culture medium in hypoxia but not in normoxia. This acidification can be perturbed by deletion of the enzyme active site and inhibited by CA IX-selective sulfonamides, which bind only to hypoxic cells containing CA IX. Our findings suggest that hypoxia regulates both expression and activity of CA IX in order to enhance the extracellular acidification, which may have important implications for tumor progression.
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PMID:Hypoxia activates the capacity of tumor-associated carbonic anhydrase IX to acidify extracellular pH. 1555 24

Ductal cells of the pancreas form the epithelial lining of the branched tubes that deliver enzymes produced by pancreatic acinar cells into the duodenum. In addition, these cells secrete bicarbonate that neutralizes stomach acidity. During development, epithelium of endodermal origin evaginates from the future duodenum area and invades the mesenchyme to form a complex branched network. All endocrine, acinar and ductal cells arise from common precursors in this epithelial structure. Adult ductal cells share some similarities with embryonic primitive ducts and may retain the ability to generate endocrine cells in the adult. Based on challenged pancreas regeneration experiments, the adult ductal cells have been proposed to be pancreatic stem cells but their role in normal endocrine cell turnover has recently been challenged. Manipulating their ability to give rise to endocrine cells may open new avenues in the treatment of diabetes and therefore they have recently been under scrutiny. In addition, in the main form of pancreatic cancer, pancreas adenocarcinoma, tumor cells share similarities with ductal cells. The secrets of an appropriate therapy for this deadly cancer may thus reside in the biology of ductal cells.
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PMID:Ductal cells of the pancreas. 1561 5

The microenvironment within solid tumors is slightly acidic, and manipulation of this extracellular acidity to cause intracellular acidification might be used to increase selective antitumor effects of some anticancer drugs. Potential mechanisms include inhibition of repair of DNA damage and inhibition of repopulation of tumor cells between successive courses of chemotherapy. Here, we evaluate the influence of extracellular pH (pHe) and of two agents that lead to intracellular acidification (cariporide and S3705) on toxicity of melphalan for two human breast cancer cell lines (MDA-MB231 and MCF7). Both the total number and number of colony-forming cells were evaluated during and after three sequential weekly drug treatments. Our results indicate the following: (a) Slow or absent repopulation after the first course of treatment that is influenced minimally by pHe. (b) Rapid repopulation after the second course of treatment that may be inhibited at low pHe. (c) Effects of low pHe following treatment with melphalan to increase cell kill. (d) Small effects of incubation in cariporide and S3705 at low pHe to increase the net cell kill after treatment with melphalan. Although these results add to evidence that manipulation of intracellular pH within the acidic environment of solid tumors can influence the effects of chemotherapy, they are too small and inconsistent to warrant clinical evaluation.
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PMID:Reduction of intracellular pH as a strategy to enhance the pH-dependent cytotoxic effects of melphalan for human breast cancer cells. 1586 59


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