Search results for "oxygenation"
showing 10 items of 237 documents
Vascularity, perfusion rate and local tissue oxygenation of tumors derived from ras-transformed fibroblasts.
2007
Tumors derived from ras-transformed rat fibroblasts were investigated in order to gain insight into possible interrelationships between oncogenic transformations and therapeutically relevant parameters of the metabolic micromilieu of solid tumors in vivo. Tumors grew in nude mice after injection of in vitro-passaged cells. Growth rates, early stages of angiogenesis, perfusion and tissue oxygenation were assessed. Compared with the parental cell line, both ras transformants grew very rapidly and exhibited an early onset of angiogenesis. Perfusion rates of one ras-transformed tumor line were similar to those of the parental tumors whereas reduced flow values were detected in tumors of the oth…
Hypoxia and radiation response in human tumors
1996
This study demonstrates by an updated analysis of an ongoing prospective study that tumor oxygenation, as measured with a validated standardized polarographic needle electrode method before treatment, powerfully predicts the prognosis of patients receiving radiotherapy for intermediate and advanced stage cancer of the uterine cervix. First evidence for a host component in tumor oxygenation based on a significant correlation between median pO 2 values determined in normal subcutaneous fatty tissue and in cervical cancer is also presented. Further investigations are necessary to clarify whether tumor hypoxia is just a marker of intrinsic tumor aggressiveness or whether the negative impact of …
Carbonic anhydrase IX expression and tumor oxygenation status do not correlate at the microregional level in locally advanced cancers of the uterine …
2005
Abstract Purpose: Carbonic anhydrase IX (CA IX) can be induced by hypoxia in vitro and shows an immunohistochemical expression pattern that is predominantly found in perinecrotic tumor areas and correlates with exogenous markers of hypoxia, such as pimonidazole. CA IX might therefore serve as an endogenous marker of tumor hypoxia, although comparisons of CA IX immunostaining with direct oxygenation measurements using pO2 microsensors have thus far yielded contradictory results. Experimental Design: Because tumor heterogeneity may be among the factors responsible for the discrepancy between the two methods, CA IX expression in tissue samples originating from oxygen microelectrode tracks of l…
Tissue gradients of energy metabolites mirror oxygen tension gradients in a rat mammary carcinoma model
2001
Abstract Purpose: It has been shown that oxygen gradients exist in R3230AC tumors grown in window chambers. The fascial surface is better oxygenated than the tumor surface. The purpose of the present study was to determine whether gradients exist for energy metabolites and other end points related to oxygen transport. Methods and Materials: Imaging bioluminescence was used to measure ATP, glucose, and lactate in cryosections of R3230AC tumors. Mean vessel density and hypoxic tissue fraction were assessed using immunohistochemistry. Tumor redox ratio was assessed by redox ratio scanning. Results: Lactate content and hypoxic fraction increased, whereas ATP, glucose, redox ratio, and vessel de…
Optimal Pre-Oxygenation: The Nasoral-System
1994
The human body’s intra-and extrapulmonary O2 reserves, i.e. the oxygen stores of the functional residual capacity (FRC) and the blood, will be rapidly depleted during any kind of respiratory arrest (apnea). Application of oxygen prior to iatrogenic apnea (e.g. for endotracheal intubation procedures), therefore, commonly is discussed [e.g. Miller, 1990] as the proposed measure designed to achieve an increase in the human body’s oxygen stores sufficient to avoid hypoxemia. This prophylactic application of oxygen simply has become to be termed “pre-oxygenation”, regardless of the amount of increase in the O2 stores actually achieved. A myriad of different techniques and procedures are practica…
Effect of Supplemental Oxygen versus Dobutamine Administration on Liver Oxygen Tension in dPP-Guided Normovolemic Pigs
2008
<i>Background:</i> Difference in pulse pressure (dPP) confirms adequate intravascular filling as a prerequisite for tissue perfusion. We hypothesized that both oxygen and dobutamine increase liver tissue oxygen tension (pt<i>O</i><sub>2</sub>). <i>Methods:</i> Eight anesthetized pigs received dPP-guided fluid management. Hepatic p<i>O</i><sub>2</sub> was measured with Clark-type electrodes placed subcapsularly, and on the liver surface. Pigs received: (1) supplemental oxygen (F<sub>i</sub><i>O</i><sub>2</sub> 1.0); (2) dobutamine 2.5 μg/kg/min, and (3) dobutamine 5 μg/kg/min. Data wer…
Description of the response of a new multi-parametric brain sensor to physiological and pathophysiological challenges in the cortex of juvenile pigs
2014
AIM Monitoring of intracranial pressure (ICP), local cerebral blood flow (CBF) and oxygen is part of modern intensive critical care medicine. Preclinical evaluation of newly developed catheters that should monitor several parameters simultaneously is reported poorly in the literature. The goal of our study was (1) to evaluate a new multi-parametric sensor in brain tissue and (2) to establish a testing protocol using pathophysiological challenges that target measured parameters of the sensor and autoregulatory boundaries and could be used as preclinical standard protocol in future studies. MATERIAL AND METHODS We describe data from 12 new multi-parametric brain sensors (MPBS) that were impla…
Tumor Oxygenation and Tumor Vascularity: Evidence for Their Clinical Relevance in Cancer of the Uterine Cervix and Considerations on Their Potential …
1996
Most solid malignancies are thought to be derived from a single neoplastic precursor cell having lost proliferation control and gained the ability to penetrate basement membranes and to invade into the stroma. During the disease course tumors increase their overall cell number by local expansion and the development of regional and distant metastases. Along with the increase in cell number the tumors loose hormonal or other external signal dependencies and acquire resistances towards radio— and chemotherapy. The progressing disease causes symptoms through impaired tissue/organ functions and complications, and finally kills the individual (unless other causes leading to death become manifest …
Oxygenation of Cervix Cancers: Impact of Clinical and Pathological Parameters
2003
Current knowledge on the oxygenation status of carcinomas of the uterine cervix is mostly based on pretherapeutic data obtained in pre-and postmenopausal women. Mean and median 02 tensions (pO2) obtained from >20,000 p02-measurements in more than 400 squamous cell carcinomas of the uterine cervix observed by several research groups were, on average, distinctly lower than in normal tissues. Oxygen tensions measured in the normal cervix of nullipara patients revealed a median pO2 of 42 mmHg, whereas in conscious patients with locally advanced cancers of the cervix (stage FIGO lb-IVa), the median pO2 values were 10-20 mmHg. In patients under general propofol-anesthesia the median p02 values we…
Predictive Power of the Tumor Oxygenation Status
1999
In most solid tumors the tissue pO2 status is poorer than in normal tissue at the site of tumor growth (for reviews see Vaupel et al., 1996, 1998; Vaupel and Hoeckel, 1998). Peculiarities of tumor tissue oxygenation can mainly be attributed to characteristic structural and functional abnormalities of the tumor microcirculation (perfusion-limited O2 delivery), to a deterioration of the diffusion-geometry (diffusion-limited O2 delivery), and—in some cases—to a reduced O2 carrying capacity of the blood due to tumor-associated anemia.