Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been shown polarographically that the oxygen supply and consumption in transplantable Heren carcinoma and normal tissues of the tumor organism are reduced as compared with such indices in intact animals. As the tumor grows, oxygen tension in normal tissues is gradually lowered both under normal conditions and oxygen ventilation, while the time of its consumption by tissues is longer. Such changes in tissues pO2 are not observed in subcutaneous transplantation of muscle tissue suspension in animals and also in transplantable tumor resorption.
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PMID:[Oxygen tension in the tissues of animals during the process of malignant tumor growth]. 100 40

The present study was undertaken to explore the relationship of the time interval between application of heat and irradiation on enhanced tumor cell sensitivity. Using the Ridgway osteogenic sarcoma grown in AKD2F1/J mice, local tumor hyperthermia (42.5 +/- .5 degrees C for 15 minutes) was applied at various time intervals before or after single or fractionated doses of x irradiation. Enhancement of tumor cell sensitivity by combined treatment with radiation and heat, as measured by delay in tumor growth, cure rates, and mean survival times was inversely proportional to the time interval between application of both modalities. The interactions associated with this increased sensitivity appear to be transitory, diminishing with time between treatments. Possible mechanisms of action for thermal sensitization may involve the reduction of oxygen dependence as well as a reduced recovery capacity of tumor cells.
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PMID:The relationship between the time of fractionated and single doses of radiation and hyperthermia on the sensitization of an in vivo mouse tumor. 105 37

Aflatoxin B1-2,3-dichloride (AFB1-Cl2) was synthesized as a model for the probable ultimate carcinogen, aflatoxin B1-2,3-oxide. As expected for aflatoxin B1-2,3-oxide, AFB1-Cl2 has an electrophilic carbon 2; it decomposed in water (half-life of 0.5 min in 10% dimethyl sulfoxide, pH 7.4) with the formation of 3-chloro-2,3-dihydro-2-hydroxyaflatoxin B1 and 2,3-dihydro-2,3-dihydroxyaflatoxin B1. AFB1-Cl2 formed covalent adducts with DNA and RNA with retention of one-half of the chlorine; the major products apparently contained glycosidic bonds between carbon 2 of the aflatoxin residues and nitrogen or oxygen atoms in the nucleic acids. Polyguanylic acid was the most reactive homopolymer toward AFB1-Cl2. AFB1-Cl2 was less reactive toward mononucleotides than toward polynucleotides. The major adducts formed on incubation of AFB1-Cl2 with protein contained little chlorine and could have resulted from alkylation of primary amino groups or from reactions with the hydrolysis products. Similarly, incubation of AFB1-Cl2 with amino acids apparently resulted in Schiff base formation between primary amino groups and the dialdehyde rearrangement forms of the hydrolysis products of AFB1-Cl2. AFB1-Cl2 was much more active than aflatoxin B1 in inducing sarcomas at the s.c. injection site in rats, in the initiation of papillomas on the skin of mice, and in the induction of lung tumors in mice. AFB1-Cl2 was also highly mutagenic for Salmonella typhimurium TA 98 and TA 100. Aflatoxin B1 and its 2,3,-dihydro- (aflatoxin B2), 2,3-dihydro-2-hydroxy- (aflatoxin B2a), 2,3-dihydro-2,3-dihydroxy-, and 3-chloro-2,3-dihydro-2-hydroxy- derivatives were inactive in the mutagenicity tests; and the latter four compounds were also inactive as initiators of papillomas of the skin in mice. The structures of the macromolecular adducts of AFB1-Cl2 formed in vitro, the carcinogenicity of this electrophile, and the lack of carcinogenicity of its hydrolysis products indicate that alkylation of nucleic acids is a critical reaction in tumor induction with this carcinogen and aflatoxin B1.
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PMID:The reactivity and carcinogenicity of aflatoxin B1-2,3-dichloride, a model for the putative 2,3-oxide metabolite of aflatoxin B1. 110 59

The clinical course of a woman with metastatic reticulum cell sarcoma and intractable lactic acidosis is described. Although her illness was dominated by a myelopathy, she developed severe lactic acidosis which could not be related to decreased tissue oxygen delivery. Necropsy showed extensive hepatic replacement with tumor and widespread disease. This and other possible pathogenetic factors causing lactic acidosis are discussed.
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PMID:Metastatic reticulum cell sarcoma and lactic acidosis. 110 35

Lewis lung tumor cells were irradiated with 60Co gamma-rays or cyclotron-produced neutrons in situ as solid s.c. tumors or in vitro as single cell suspensions. Cell survival was assayed by colony formation both in vitro in soft agar and in the lungs of isogeneic recipient mice. Survival curve characteristics measured in vitro were: Do = 111 rads, Dq = 342 rads, n = 22 for gamma-rays, and Do = 61 rads, Dq = 46 rads, n = 2 for neutrons. In situ, the hypoxic fraction was 0.36. Irradiation in situ gave, for the hypoxic subpopulation, Do = 315 rads for gamma-rays and Do = 91 rads for neutrons. The oxygen-enhancement ratio for gamma-rays was 2.8 and for neutrons was 1.5. Using the split-dose technique, in which two equal doses were administered, separated by 4 hr chronically hypoxic tumor cells repaired sublethal damage, assayed by leaving tumor cells in situ up to 24 hr posttreatment, could not be detected after neutrons, but after gamma-rays it was observed as a 3- to 6-fold increase in survival. The repair of potentially lethal damage increased the relative biological effectiveness of neutrons from 3.7 at a survival level of 5% when assayed immediately after treatment to 4.7 when assayed 6 to 24 hr after treatment. These observations, primarily limited to the chronically hypoxic subpopulation of tumor cells, suggest that decreased repair of potentially lethal damage as well as sublethal damage may be an important radiobiological difference between the effects of high and low linear energy transfer radiation.
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PMID:Repair of radiation damage in Lewis lung carcinoma cells following in situ treatment with fast neutrons and gamma-rays. 112 Mar 1

Pentobarbital depressed macromolecular synthesis in Ehrlich ascites cells in vitro, and this depression was proportional to a decrease in oxygen consumption. However, survival time of animals bearing Ehrlich ascites cells was unaffected by pentobarbital. The acute toxicity of the drug was greatly enhanced by the presence of the tumor. Sleeping time was prolonged in mice carrying the following tumors: Ehrlich ascites, Sarcoma 180 ascites, and Yancy plasma cell solid. Seven-day Ehrlich ascites tumor-bearing animals treated with pentobarbital slept about three times longer than normal mice, but both groups awoke at the same plasma levels of the unbound drug. The plasma half-life of unchanged pentobarbital was about four times as long in tumor-bearing mice as it was in controls. No qualitative difference in catabolism other than rate was detected. Renal excretion of unchanged pentobarbital in tumor-bearing animals was 50% of control animals during the first 4 hr. In tumor-bearing mice the sleeping time of the nonmetabo ble barbiturate, barbital, was identical with that in normal animals. These data suggest that the tumor affected mainly pentobarbital metabolism. Tumor-bearing mice still responded to the pharmacological challenge of phenobarbital with the apparent induction of drug metabolizing enzymes. The prolonged pentobarbital sleeping time in tumor-bearing mice required the development of some type of tumor-host relationship.
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PMID:Physiological disposition of pentobarbital in tumor-bearing mice. 112 Mar 16

A model for the growth of a tumor by diffusion is considered for spheroids which are grown in a normal medium in suspension culture. The experimental evidence indicates that, upon the onset of necrosis in the centre of the spheroid, the viable rim thickness decreases relatively slowly. This evidence contradicts the results of the usual model in which the oxygen consumption per unit volume is assumed to be constant. The proposed model assumes that the oxygen concentration is constant above a critical value, and proportional to the concentration below this critical value. The viable rim thickness of the spheroid, as a function of the necrotic radium, varies markedly over the range of the parameters in this model. By suitably choosing these parameters, the results of this model agree with the experimental evidence.
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PMID:Model for the growth of a solid in vitro tumor. 113 72

An increase of the radiosensitivity can be obtained by means of microwave use in combination with sparsely ionizing radiation. Comparing the therapeutic effect on the model of an euoxic tumor (mice testicles) with a tumor that contains important parts of hypoxic cells (solid tumor of Ehrlich) it appears that the sensitization evidentely is seen in the hypoxic tumor first of all. No sensitization can be obtained on the euoxic profileration tissue on the testicles. The temperature enhancement ratio (equal TER) does not increase linearly with increasing temperature, but is the greatest within the scope of 41 degrees C. The mere heat effect appears in the foreground with high temperatures (43 degrees C and more). The high frequency application lets hope a solution of the oxygen problem in radiotherapy and could substitute the use of heavy particles (high LET) in the combination with sparsely ionizing radiation as far as a concentration of high frequency and heat on the tumor succeeds in.
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PMID:Microwaves in radiotherapy of tumors - alternative to heavy particles? 113

Tumor cell survival characteristics were assessed following 60Co gamma-irradiation of the Lewis lung carcinoma as 500-cu mm s.c. tumors or as 0.5-cu mm (1 mm in diameter) pulmonary metastases. Cells in the small pulmonary tumors were markedly more radiosensitive (D0 = 106 rads; hypoxic fraction less than 0.005) than were those in large s.c. tumors (final D0, 315 rads; hypoxic fraction, 0.36). When pulmonary metastases were excised and irradiated intact under well-oxygenated conditions in vitro, the hypoxic fraction rose to 0.30. This implies that, under normal in situ conditions, these nodules contain a microvascular system that achieves adequate oxygen supply to the great majority of tumor cells. Thus, the tumor cells within these small metastatic implants were more sensitive to irradiation, largely due to better oxygenation, and may be more sensitive to chemotherapy, due to better drug availability.
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PMID:Tumor size dependency in the radiation response of the Lewis lung carcinoma. 114 47

Eight patients are presented in whom obesity developed in association with documented hypothalamic lesions. These lesions included trauma, inflammatory disease, an aneurysm of the internal carotid artery, and five cases of tumor. Detailed metabolic studies were performed in four patients with hypothalamic obesity and in five age- and weight-matched patients with essential obesity(i.e., obesity with no definable etiology). Fasting insulin concentrations were significantly higher in the patients with hypothalamic obesity. During a seven-day fast the insulin levels in patients with essential obesity decreased by 24 to 48 hours, whereas patients with hypothalamic obesity showed a variety of changes; In three out of four of these patients with hypothalamic obesity there was no evidence for hyperplasia of the fat cells. Basal oxygen consumption, body composition, and metabolism of adipose tissue did not differ between the patients with essential obesity and those with hypothalamic obesity. There was no difference in activity of the enzymes in the glycerophosphate cycle. Our data on eight patients with hypothalamic obesity were compared with data on patients in literature. Most cases of hypothalamic obesity occur with space-occupying tumors arising at the base of the hypothalamus. However, trauma, inflammatory diseases, and leukemia are also associated with hypothalamic obesity. Patients with hypothalamic obesity rarely weigh more than 140 kg.
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PMID:Manifestations of hypothalamic obesity in man: a comprehensive investigation of eight patients and a reveiw of the literature. 115 72


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