Search results for "oxygenation"
showing 10 items of 237 documents
Blood Flow and Oxygen Supply to Human Mammary Carcinomas Transplanted into Nude Rats
1985
Tumor blood flow (TBF), by itself, greatly influences the efficiency of nonsurgical therapeutic modalities, especially chemotherapy and hyperthermia. Furthermore, TBF is one of the most important determinants of tumor tissue oxygenation in vivo, thus playing a relevant role in tumor growth kinetics and in the development of regressive changes. In addition, the oxygenation of tumor tissue strongly determines the efficiency of radiation therapy and to a certain extent, pharmacodynamics of some antiproliferative drugs. Despite the considerable information available for rodent tumor systems, there are only sporadic ireports on blood flow (Beaney et al., 1984, Johnson, 1976, Mantyla, 1979, Manty…
No Sustained Improvement in Tumor Oxygenation After Localized Mild Hyperthermia
2009
This study has attempted to address the controversy concerning sustained increases in tumor oxygenation upon localized mild hyperthermia. While some previous studies have reported transient increases, others have reported persistent increases in tumor oxygenation, lasting for upto 2 days after application of mild hyperthermia. In order to determine changes in oxygenation at clinically relevant tumor temperatures, experimental tumors in rats underwent localized hyperthermia at either 40, 41.8°C or 43°C for 1 h using water-filtered infrared-A irradiation. Oxygenation was continuously measured before, during and upto 60 min after hyperthermia in the tumors of anesthetized rats using oxygen-sen…
Microcirculatory Function, Tissue Oxygenation, Microregional Redox Status and ATP Distribution in Tumors Upon Localized Infrared-A-Hyperthermia at 42…
2003
Since local hyperthermia (HT) affects microenvironmental parameters, the aim of the study was to analyze the impact of 42°C-HT on microcirculatory function, tumor pO2, microregional redox status and ATP distribution in experimental rat tumors. Subcutaneously growing DS-sarcomas were treated with localized HT using infrared-A radiation resulting in a mean tumor temperature of 42°C. The relative red blood cell (RBC) flux in the tumor was assessed using the laser Doppler technique and the mean tumor pO2 measured continuously using O2-sensitive catheter electrodes. In a second series of experiments, the microregional distribution of the mitochondrial redox status and ATP concentration was measu…
TISSUE OXYGENATION AND NORMAL AND HYPERTHERMIC CONDITIONS
1981
Publisher Summary This chapter describes the tissue oxygenation and normal and hyperthermic conditions. The knowledge of the effect of hyperthermia on tumor and normal tissue blood flow is important not only for the effect of hyperthermia on hypoxic cells at the time of radiation, but also for differential tumor heating. There is considerable evidence from plethsmography that an elevation of normal tissue temperature to 41°C is accompanied by a considerable increase in blood flow. The chapter discusses studies that were conducted to examine changes in the microenvironment of normal and tumor tissue as measured directly with ultramicroelectrodes. In situ studies were carried out in fourth ge…
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.
Do Changes in Tumor Blood Flow Necessarily Lead to Changes in Tissue Oxygenation and in Bioenergetic Status?
1994
An increasing number of investigations carried out in recent years provide evidence suggesting that “chronic” decreases in tumor blood flow and/or tissue oxygenation (e.g., during tumor growth) or acute declines in the tissue perfusion (e.g., following therapeutic measures) might be accompanied by significant reductions in the energy status. In several instances, positive correlations between energy status and tumor blood flow or oxygenation have been reported (Lilly et al., 1985; Evelhoch et al., 1986; Tozer et al., 1989; Vaupel et al., 1989a, 1989b; Steen and Graham, 1991), and these investigations have led to the conclusion that blood flow may be the limiting factor in determining the bi…
Transnasal Humidified Rapid Insufflation Ventilatory Exchange With Nasopharyngeal Airway Facilitates Apneic Oxygenation: A Randomized Clinical Noninf…
2020
Background: Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) was used to extend the safe apnea time. However, THRIVE is only effective in patients with airway opening. Nasopharyngeal airway (NPA) is a simple device that can help to keep airway opening. This study aimed to investigate the noninferiority of NPA to jaw thrust for airway opening during anesthesia-induced apnea.Methods: This was a prospective randomized single-blinded noninferiority clinical trial on the use of THRIVE in patients with anesthesia-induced apnea. The participants were randomly allocated to receive NPA or jaw thrust. The primary outcomes were PaO2 and PaCO2 at 20 min after apnea, with noninferi…
Targeted fibre-optical intrabronchial lipopolysaccharide administration in pigs – a methodical refinement for improved accuracy in respiratory resear…
2019
To establish and evaluate a standardized method of targeted, intrabronchial drug delivery in pigs.Randomized controlled trial.A total of 16 German Landrace pigs (Sus scrofa), age range 12‒16 weeks, and weighing 28‒35 kg.The animals were anaesthetized, intubated, and instrumented with extended cardiovascular monitoring. Lung injury was induced by administering via a flexible fibre-optic endoscope using 100 mL saline solution containing either 20 mg of Escherichia coli lipopolysaccharide (E. coli LPS) (n = 8) or no additive (sham, n = 8) into the two distal mainstem bronchi. The animals were monitored for 8 hours and arterial oxygenation, inspiratory pressure and arterial blood pressure were …
Development of a self-pumping extracorporeal blood oxygenation device characterized by a rotating shaft with embedded fiber packages.
2019
Introduction: To offer respiratory support for patients with lung disease, a novel technological solution for blood pumping and oxygenation is being developed. The pump–lung system was designed to integrate fiber membranes into six packages radially embedded in a rotating hollow shaft placed along the longitudinal axis of the device. Fiber packages are inclined with respect to the rotation axis so that the rotational motion of the rotating shaft allows a self-pumping system to be obtained. Method: Both hemodynamic and gas transfer performances were investigated using both in vitro experiments and in silico flow analyses. Results: The predicted flow velocity in the pump chamber was smooth an…
Acute Effects of Tumor Necrosis Factor-α or Lymphotoxin on Oxygenation and Bioenergetic Status in Experimental Tumors
1994
Recombinant human tumor necrosis factor-α (rhTNF-α) exerts direct cytolytic and cytostatic effects on tumor cells in vitro (Fiers,1991).In vivo,indirect actions on the tumor microvasculature have been described, such as the formation of fibrin thrombi (Nawroth et al.,1988),which cause stasis and damage of tumor microvessels with subsequent hemorrhagic necrosis.