Search results for " Induced"
showing 10 items of 461 documents
Experimental evidence for a hyperthermia-induced breakdown of tumor blood flow during normoglycemia
1983
A compilation of experimental data is presented indicating that hyperthermia alone can achieve a significant inhibition of tumor blood flow if appropriate heat exposure times and tissue hyperthermia levels are chosen.
Tumour-growth inhibition by induced hyperglycaemia/hyperlactacidaemia and localized hyperthermia.
1996
The present study was undertaken to exploit pathophysiological properties of solid tumours for a tumour-specific therapy. Experiments were carried out on DS-sarcomas implanted s.c. in the hind foot dorsum of Sprague Dawley rats. Treatment strategies included tumour acidification, lactate accumulation and disturbance of the microcirculation by induced systemic hyperglycaemia/hyperlact-acidaemia (15-25/10 mmol/L; for 60 min) as well as localized hyperthermia (water-bath; 43 degrees C, 30 min.). A special infusion solution was developed for the systemic treatment containing glucose, lactic acid and organic buffer without inorganic ions. Growth kinetics of tumour volume and animal survival were…
Laser Doppler flowmetry in subepidermal tumours and in normal skin of rats during localized ultrasound hyperthermia.
1988
Laser Doppler flowmetry has been applied to normal skin and to subepidermal tumours during localized ultrasound hyperthermia in the rat. In normal skin, 40 degrees C hyperthermia only induced a marginal increase in the red blood cell flux. Significant increases occurred after 20 min at 42 degrees C and after 4 min at 44 degrees C. During 44 degrees C hyperthermia maximum fluxes were reached after 24 min. Thereafter, the flow declined and finally approached preheating values. In contrast, in subepidermal tumours 40 degrees C hyperthermia on the average induced a slight decrease of the flux. During 42 degrees C hyperthermia a significant flow decrease was found after 40 min of heating. Follow…
Enhanced effects of aminolaevulinic acid-based photodynamic therapy through local hyperthermia in rat tumours.
2003
The possibility of enhancing aminolaevulinic acid (ALA)-based photodynamic therapy (PDT) by simultaneous application of localised hyperthermia (HT) was evaluated. Treatments of rat DS-sarcomas included: (i) control, (ii) ALA administration (375 mg kg(-1), i.p.), no illumination, (iii) 'nonthermal' illumination, (iv) ALA-PDT: that is, ALA administration, 'nonthermal' illumination, (v) localised HT, 43 degrees C, 60 min (vi) ALA-PDT+HT: ALA administration with full spectrum irradiation resulting in ALA-PDT and HT. Tumour volume was monitored for 90 days or until a target volume (3.5 ml) was reached. No differences were seen between the first three groups, with all tumours reaching the target …
Relation between autoradiographically measured blood flow and ATP concentrations obtained from imaging bioluminescence in tumors following hypertherm…
1993
The effects of moderate local hyperthermia (43.3 degrees C/30 min) on regional blood flow and regional ATP distribution in the amelanotic hamster melanoma A-Mel-3 were investigated by high-resolution techniques. Blood flow and ATP concentrations were measured simultaneously in treated and untreated tumors and in adjacent tissues by means of (14C)-Iodoantipyrine autoradiography and quantitative imaging bioluminescence in consecutive tissue sections at 3, 12 and 24 hr following treatment. Digital image processing and the use of a special algorithm allowed the regional interrelationship of the 2 parameters to be quantified. Measurements revealed a great heterogeneity of blood flow and ATP betw…
Response of tumour red blood cell flux to hyperthermia and/or hyperglycaemia.
1989
Laser Doppler flowmetry has been applied to subepidermal rat tumours during localized ultrasound hyperthermia and/or moderate, short-term hyperglycaemia. Blood glucose levels were elevated 4-fold by continuous i.v. infusion of D-glucose (4.8 g/kg/60 min). To determine whether the effects of hyperglycaemia on tumour blood flow involved increased rates of glycolysis and lactic acid production, galactose, a sugar not metabolized by the tumour, was administered using the same dose schedule. Hyperglycaemia was accompanied by a 3-fold increase in blood lactate levels and a slight hypervolaemic haemodilution without any significant systematic changes of the arterial blood pressure or respiratory b…
Tumour tissue monitoring during photodynamic and hyperthermic treatment using bioimpedance spectroscopy.
2003
Electrical bioimpedance spectroscopy is a fast and relatively easily applicable method for tissue characterization. In the frequency range up to 10 MHz, current conduction through tissue is mainly determined by tissue structure, i.e. the extra- and intra-cellular compartments and the insulating cell membranes. Therefore, changes in the extra- and intra-cellular fluid volumes are reflected in the impedance spectra. Investigations of tumours (DS sarcoma, implanted on the hind foot dorsum of rats) during treatment with localized hyperthermia (HT), photodynamic therapy (PDT) and the combination of these two components were carried out using impedance spectroscopy in the frequency range of 37 Hz…
The influence of tumor blood flow and microenvironmental factors on the efficacy of radiation, drugs and localized hyperthermia.
1997
It is generally accepted that tumor blood flow, microcirculation, oxygen and nutrient supply, tissue pH distribution, and the bioenergetic status-factors which are usually closely linked and which define the so-called metabolic microenvironment--can markedly influence the therapeutic response of malignant tumors to conventional irradiation, chemotherapy, other nonsurgical treatment modalities, and the cell proliferation activity within tumors. Currently available information on the parameters defining the metabolic micromilieu in human tumors is presented in this review. According to these data, significant variations in these relevant factors are likely to occur between different locations…
Ultrasound hyperthermia induces apoptosis in head and neck squamous cell carcinoma: an in vitro study
2016
Background Hyperthermia is considered an efficient complement in the treatment of head and neck squamous cell carcinoma (HNSCC). Hyperthermia induces cell apoptosis in a temperature- and time-dependent manner. However, the molecular mechanism of hyperthermia remains unclear. The aim of this study was to investigate the mechanism of apoptosis induced by ultrasound hyperthermia in HNSCC cell lines HN-30 and HN-13. Material and Methods We examined the dynamic changes of early apoptosis and secondary necrosis in HN-30 and HN-13 cells treated by hyperthermia at 42°C for 10 min. We further examined mitochondrial membrane potential in vitro by ultrasound hyperthermia for different heating temperat…
Impact of Localized Microwave Hyperthermia on the Oxygenation Status of Malignant Tumors
1982
Considerable insight into the mechanisms of heat induced cell death in vitro has been gained during recent years (for reviews see 1–3). Besides the direct cell killing effect of heat, many microenvironmental or milieu factors seem to play an important role during heat treatment of solid tumors in vivo, such that a preferential effect of hyperthermia on tumors has been postulated for the in situ conditions. Environmental factors affecting the tumor milieu, such as tissue oxygen partial pressures, pH values, glucose (?) and lactate levels, nutrient supply and drainage of wastes, have thus become a subject of topical interest.