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

Development of thermotolerance has been observed in diverse biological systems. Despite the important role of blood circulation in heat-induced tissue damage, little is known about vascular thermotolerance. The kinetics of vascular thermotolerance in SCK tumors of A/J mice was investigated in this study. A single heating at 43.5 degrees C or 44.5 degrees C for 1 hr caused marked damage in tumor vasculature, as demonstrated by a marked decrease in Rb-86 uptake (% of injected dose/g of dried tissue). The tumor vasculature became resistant or tolerant to subsequent heatings at those temperatures when the tumors were preheated at 42.5 degrees C for 1 hr. Vascular thermotolerance became significant at 5 hr and reached its maximum at 18 hr after preheating at 42.5 degrees C. When the vascular thermotolerance was at its peak, heating at temperatures as high as 44.5 degrees C for 1 hr could not reduce the tumor blood flow. The vascular thermotolerance decayed considerably but not completely at 72 hr after the preheating. The vascular thermotolerance may exert a profound implication on the response of tissues, including tumors, to multiple heatings.
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PMID:The kinetics of vascular thermotolerance in SCK tumors of A/J mice. 277 70

The tumor-inherent vasculature plays a major role with respect to tumor sensitivity to ionizing radiation. Ultrastructural studies of the tumor vasculature are necessary in order to obtain more detailed information on the architecture and structure and on the sites affected by tumor therapy. The vasculature of xenotransplanted human tumors on nude mice was investigated in this study by means of scanning and transmission electron microscopy. Structurally complete, real arteries or veins are neither to be seen in the periphery nor in the center. Large-caliber vessels basically have a capillary wall structure. The endothelial cells show a very alternating height and electron density. Frequently, different cell types and tumor cells themselves are apparently involved in the formation of the vessel wall. The endothelium is characterized by very simple, immature cell contacts. In some tumors, the amount of vessels without or with incomplete endothelium seems to be higher than the number of structurally real capillaries. This has consequences as well for radiotherapy as for hyperthermia and chemotherapy.
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PMID:The vasculature of xenotransplanted human melanomas and sarcomas on nude mice. II. Scanning and transmission electron microscopic studies. 281 52

Flavone acetic acid (FAA) is active against normally refractory murine sc tumors. Clinical studies are disappointing despite achievement of plasma profiles associated with the antitumor murine activity in man. To clarify the mechanism of action, we have followed histologic changes, tumor blood volume, and drug concentrations in a well-differentiated, slow-growing cystic adenocarcinoma in mice. FAA causes massive tumor necrosis beginning 2 hours after treatment. Tumor plasma volumes are reduced by 2 hours after treatment and tumor blood vessels are shutdown, which suggests that tumor vasculature plays a role in the dramatic response of sc tumors in pure-strain male NMRI mice.
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PMID:Reduction of tumor blood flow by flavone acetic acid: a possible component of therapy. 291 Oct 84

Twelve patients with malignant brain tumors who had failed to respond to conventional therapies were treated with thermotherapy. Hyperthermic temperatures (approximately 43 degrees C) were induced in the tumors using microwaves at a frequency of 2450 MHz that were guided into the tumors by one or more semirigid coaxial applicators. These applicators fit into 16 gauge tubes or needles and can be inserted into the brain with minimal damage to healthy tissues. During each treatment, the tumors were maintained at hyperthermic temperatures for 1 hour. Several treatments spaced a few days apart were usually administered. The procedure used for producing hyperthermia in brain tumors with microwaves proved to be safe and could be repeated several times without producing toxic effects. Objective tumor responses were obtained in 75% of the patients (decrease in tumor size, 3 patients; slowing of tumor growth, 2 patients; necrosis of tumor tissues verified by pathological examination, 4 patients). Favorable clinical responses were observed in 75% of the patients (rapid decrease in intractable headaches, 5 patients; improvements in clinical deficits, 4 patients). Also, in all patients, the microwave power required to heat for a given time or a given volume decreased during most of the thermotherapy sessions, possibly because of heat damage to the tumor vasculature. Our results, taken together with the results of other investigators, indicate that thermotherapy is a promising modality for treating malignant brain tumors, either as the sole therapy or in combination with radiotherapy and chemotherapy. The next logical steps would be Phase I/II type trials of subjects whose disease is less advanced than the disease of patients treated in the current series of investigations.
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PMID:Microwave hyperthermia for brain tumors. 299 66

The immunohistochemistry of the epidermal growth factor receptor (EGFR) was studied with monoclonal antibodies in 12 meningiomas of various histologic subtypes, nine benign and three malignant. Strong immunoreactivity of EGFR epitopes was found in the endothelia of the tumor vasculature in six cases. A much weaker reaction was detected within tumor cells in six cases, in one of which it was diffuse and five focal. No correlation was established between the presence of EGFR epitopes and the histologic type or biologic behavior of the meningiomas. The results suggest that the EGFR may participate in tumor angiogenesis, but its role in the growth of neoplastic meningioma cells remains elusive.
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PMID:Epidermal growth factor receptor in meningiomas is expressed predominantly on endothelial cells. 305 82

The relationship between heat-induced vascular damage and thermosensitivity was studied using four mouse transplantable tumors. The tumors used were spontaneous mammary carcinoma, SCC VII carcinoma, EMT6 sarcoma, and B16 melanoma. Under cultured conditions, B16 was more thermosensitive at 43 degrees C and 44 degrees C than SCC VII or EMT6. The in vivo tumor response to heat was evaluated by the growth delay after heating at 44 degrees C for 30 min. Among the four tumors, SCC VII was the most thermosensitive in vivo followed by EMT6, whereas B16 and spontaneous mammary carcinoma were thermoresistant. Vascular damage was studied quantitatively up to 24 h after heating by using microangiography. The order of the four tumors in vascular damage was well correlated with the tumor response in vivo. Histologically, tumor vessels of spontaneous mammary carcinoma were supported by connective tissues, and those of B16 had dense endothelial cells, compared to sparse endothelial cells of SCC VII and EMT6. Our findings suggest that variability in heat sensitivity of tumors is related to variation in the histological structure of tumor vasculature. That is, tumor vasculature with perivascular connective tissues and/or dense endothelial cells is less heat labile than that composed only of sparse endothelial cells.
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PMID:Relationship between heat-induced vascular damage and thermosensitivity in four mouse tumors. 319 94

To delineate the complex relationships between overall tumor oxygenation and vascular configuration, intravascular oxyhemoglobin (HbO2) saturation distributions were measured with cryospectrophotometric techniques. Four factors related to vascular morphometry and tumor growth were evaluated: a) vessel diameter, b) distance of vessel from the tumor surface, c) tumor volume, and d) vascular density. To measure intertumor heterogeneity, two murine sarcomas (RIF-1 and KHT) and two human ovarian carcinoma xenografts (OWI and MLS) were utilized. In contrast to skeletal muscle, a preponderance of very low HbO2 saturations was observed for both large and small tumors of all lines. Saturations up to about 90% were also generally present, however, even in very large tumors. Variations in vascular configuration were predominantly tumor-line dependent rather than due to inherent characteristics of the host vasculature, and widely disparate HbO2 distributions were found for alternate lines implanted in identical host mice. Although peripheral saturations remained fairly constant with tumor growth, HbO2 values were markedly lower for vessels nearer the tumor center and further decreased with increasing tumor volume. HbO2 saturations did not change substantially with increasing vascular density (except for KHT tumors), although density did decrease with increasing distance from tumor surface. Combined effects of vessel diameter, tumor volume, and vessel location on HbO2 saturations were complex and varied markedly with both tumor line and vessel class. For specific classes, HbO2 distributions correlated closely with radiobiological hypoxic fractions, i.e., for tumor lines in which hypoxic fraction increased substantially with tumor volume, corresponding HbO2 values decreased, while for lines in which hypoxic fraction remained constant, HbO2 values also were unchanged. Although these trends may also be a function of differing oxygen consumption rates between tumor lines, functional alterations in the rapidly expanding tumor vasculature undoubtedly play a primary role in explaining spatial oxygenation heterogeneities.
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PMID:Cryospectrophotometric determination of tumor intravascular oxyhemoglobin saturations: dependence on vascular geometry and tumor growth. 319 79

The mode of antitumor action of rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation with respect to time course, dose-response relationships and selectivity of the effects. The maximal cytotoxic effect on tumor cells revealed by inhibition of DNA synthesis and maximal lesional effect on tumor vasculature revealed by change in blood pool-size in the tissue were detected at 30 min and 1 h after administration of rHu-TNF, respectively. The dose-response relationship between cytotoxic and tumoricidal effects of rHu-TNF was irrespective of administration route. ED50s of these antitumor effects after i.v. administration of rHu-TNF were about 50 times as high as ED50s after i.t. administration. ED50 of i.t. given rHu-TNF for vascular effect was about 20 times as high as that for cytotoxicity while ED50 of i.v. rHu-TNF for vascular effect was only 2-3 times as high as that for cytotoxicity. The whole body autoradiographies with [125I]HSA given i.v. to see the blood influx into tumor tissue and [14C]thymidine given i.v. to see DNA synthesis in the whole body after administration of rHu-TNF revealed that the distribution of radioactivity was markedly changed in the tumor alone without any detectable change in other whole body tissues. In conclusion, the in vivo antitumor effect of rHu-TNF given i.t. or i.v. appears to be exerted through the direct action on Meth A sarcoma rather than indirectly on tumor vasculature. Under present conditions, the effect of rHu-TNF in the whole body tissues seems rather selective on cells and vasculature of the tumor.
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PMID:Mode of antitumor action of recombinant human tumor necrosis factor on the sarcoma Meth A transplanted in the mouse. 327 91

The specific uptake of 125I-A6H antibody by xenografts of the human renal cell carcinoma (RCC) TK177G in the athymic mouse was considerably greater than that seen for other human tumor xenografts and their associated antibodies (e.g., 125I-B6.2 uptake by the human breast carcinoma, Clouser). In addition the A6H-RCC model also demonstrated both greater localization indices and absolute amount of antibody bound than did the B6.2-Clouser model. Several physiological factors were studied to assess whether they might play a role in this greater specific uptake. Vascular volume was determined using the in situ labeling of red blood cells with 99mTc. Vascular permeability was determined by measuring the amount of 125I-labeled bovine serum albumin and 131I-labeled nonspecific IgG1 (anti-horseradish peroxidase) extravasated out of the tumor vasculature during 1 hr. Relative blood flow to the tumor was determined using the 86Rb method. Blood flow and vascular permeability were found to be significantly greater in the RCC tumor xenografts than in Clouser tumors. Differences in vascular permeability were especially dramatic, showing the vasculature of the RCC xenograft was twice as permeable as that of the Clouser tumor. Animals bearing either RCC or Clouser xenografts were injected with a monoclonal antibody to human major histocompatibility complexes (125I-labeled anti-human histocompatibility complex A, B, C). Tumor uptake of 125I-labeled anti-human histocompatibility complex A, B, C was found to be 5 times greater in RCC than Clouser xenografts. These results, therefore, suggest that the differences seen in the physiological factors studied can account for some of the greater specific 125I-A6H uptake by the RCC tumor than 125I-B6.2 uptake by the Clouser xenograft.
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PMID:Correlation of vascular permeability and blood flow with monoclonal antibody uptake by human Clouser and renal cell xenografts. 333 93

Using a polymer casting technique in conjunction with scanning electron microscopy, the three-dimensional characterization of tumor microvasculature as a function of age of renal adenocarcinoma in the rat kidney is undertaken. The microvasculature of the rat tumor model is compared with VX2 carcinoma in the rabbit leg muscle. Light microscopy and transmission electron microscopy on the rat tumor model are performed to correlate the features seen under scanning electron microscopy of vascular casts. The casts show marked differences between tumor and normal microvasculature. The tumor vascular architecture appears disarrayed with prevalent atypical features such as coils, ribbons, sheets, dense capillary networks, saccular dilatations, leaky and otherwise highly irregular vessels. Sprouts of new growth capillaries are seen throughout the tumor casts. Compressed vessels are present and become more pronounced in older tumors. These features are not observed in normal controls treated under identical conditions. The application of this high resolution three-dimensional casting technique to tumor studies is promising for research in basic tumor mechanics as well as in the effects of tumor vasculature on mediating radiation and chemotherapy and the fundamental mechanisms of metastasis.
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PMID:Characterization of solid tumor microvasculature: a three-dimensional analysis using the polymer casting technique. 333 61


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