1,721,000 research outputs found
OXYGEN-TENSION DISTRIBUTION IN HEAD AND NECK CARCINOMAS AFTER PERORAL OXYGEN-THERAPY
No full textBackground: It has been shown that the response on radiotherapy in human tumors is correlated to the oxygen supply. Polarographic needle electrodes offer a feasible tool to determine the oxygen tension distribution in human tumors. The peroral administration of oxygen-enhanced water may be able to overcome the radioresistance in reducing hypoxic regions in larger tumors and will be analyzed. Patients and Methods: Oxygen tension distributions were determined in clinically fixed lymph node metastases in 6 patients suffering from a carcinoma of the base of the tongue (n=2), larynx (n=2), hypopharynx and tonsillar fossa before and immediately after drinking oxygen-enhanced water (20 mg/l O-2) From a pooled histogram (n=200) median pO(2), mean pO(2) and hypoxic fraction could be calculated and compared. Results: The determined pO(2) tension values showed a typical distribution for squamous cell carcinomas of the head and neck region with the proof of containing hypoxic tumor cells. After administration of oxygen-enhanced water 2 patients revealed only a marginal increase in oxygen supply. A moderate improvement in tissue oxygenation was observed in 3 patients, combined with a therapeutically relevant shift of pO(2) values from the low pO(2) classes (<10 mm Hg) to medium pO(2) classes. In 1 patient an impressive increase in the overall oxygen tissue tension could be observed. The overall mean and median pO(2) values increased after peroral oxygen therapy (POT) from 14.4 to 23.3 mm Hg and from 22.3 to 30.2 mm Hg, respectively. The hypoxic fraction was significantly reduced. Conclusion: The peroral administration of oxygen-enhanced water is a feasible technique to increase the oxygen supply to tumors. The therapeutic role should be evaluated ina larger clinical trial, combined with the invasive determination of oxygen tension distributions. The reduced hypoxic fraction seems to be promising in therapeutic irradiation
Stereotactic radiation therapy of liver metastases
No full textPurpose. A number of minimal-invasive methods have been developed for the treatment of non-resectable liver metastases. A focused high dose can be delivered to a liver tumor with sparing of surrounding normal liver tissue using non-invasive stereotactic techniques. Methods. Sixty-six metastases were treated stereotactically in 43 patients during a phase 2 trial. Results. There were no major side effects observed. The actuarial local control was 82% after 18 months. The median actuarial survival was 24 months. However, there was a significantly improved survival in patients without additional extrahepatic tumor manifestation at the time of treatment compared to those, who were treated in palliative intention (87% vs. 24% after 18 months, p=0.001 (log-rank). Conclusion. Stereotactic single dose irradiation is a non-invasive and safe treatment option for patients with inoperable liver metastases. Phase III studies will further evaluate this new approach
Acute central nervous system (CNS) toxicity of total body irradiation (TBI) measured using neuropsychological testing of attention functions
No full textPurpose: The purpose of this study was to investigate acute normal tissue damage of low irradiation doses to the healthy, adult central nervous system (CNS) using neuropsychological testing of attention functions, Methods and Materials: Neuropsychological testing (IQ, attention [modified Trail-Making Test A, Digit Symbol Test, D2 Test, Wiener Determination Machine]) was used to examine 40 patients (43 +/- 10 years) before and immediately after the first fraction (1.2 Gy) of hyperfractionated total body irradiation (TBI) at the University of Heidelberg, The patients received antiemetic premedication. Test results are given as mean percentiles +/- standard deviation, with 50 +/- 34 being normal. Thirty-eight control patients (53 +/- 15 years) were studied to quantify the influence of hospitalization, stress, and repeated testing. Results: The patients showed normal baseline test results (IQ = 101 +/- 14, attention = 54 +/- 28) and no decrease in test results after 1.2 Gy TBI, Attention functions improved (66 +/- 25) corresponding to a practice effect of repeated testing that was seen in the control group, although alternate versions of the tests were used (IQ = 104 +/- 10, attention before = 42 +/- 29, attention after = 52 +/- 31), Conclusion: Our data show no deterioration of neuropsychologic test results acutely after 1.2 Gy whole body exposure in adult patients without CNS disease receiving antiemetic medication. (C) 1999 Elsevier Science Inc
Prognostic factors for brain metastases after whole brain radiotherapy - Data from a single institution
No full textPurpose: Prognostic factors for overall survival of patients treated for brain metastases with whole brain radiotherapy (WBRT) at a single institution were retrospectively evaluated, and the validity of the RTOG recursive partitioning analysis (RPA) for prognostic classes was assessed. Patients and Methods: The data of all. patients (n = 268) with brain metastases from solid tumors homogeneously treated between 01/1997 and 09/1999 at the University of Heidelberg, Germany, with WBRT without surgery or radiosurgery were reviewed. 13 different patient- and therapy-related variables were evaluated for prognosis. Second, a grouping of the study cohort was performed according to the RTOG RPA prognostic classes. Results: Median survival of the whole population after the start of WBRT was 3.8 months. The 1-year survival rate was 19%. Muk tivariate analysis revealed that only the Karnofsky performance status, control of the primary and no extracranial disease were independent prognostic factors for overall survival. These are also the main determinants of the RTOG RPA classes. Applying the RTOG RPA classes to the authors' data set revealed three subgroups with significantly different prognosis. Conclusion: Based on this analysis, prognostic factors for survival after WBRT in patients with brain metastases could be identified. A total of 19% (n = 44/232) survived greater than or equal to 1 year, whereas overall survival was poor. The potential value of the RPA classes in estimating the patient's prognosis could be confirmed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Differential sensitivity of three sublines of the rat dunning prostate tumor system R3327 to radiation and/or local tumor hyperthermia
No full textTo better understand the relationship of the growth characteristics of tumor tissues and their response to ionizing radiation alone and in combination with local tumor hyperthermia, we compared three different tumor sublines of the Dunning rat prostate carcinoma R3327. This report includes results obtained with the anaplastic AT1 subline (volume doubling time 5.2 days), the moderately differentiated mucin-secreting HI subline (volume doubling time about 9 days) and the well-differentiated, hormone-dependent H subline (volume doubling time about 17 days). The effects of single doses of photons (10 to 40 Gy) with and without local tumor hyperthermia (35 min immersion at 43.5 degrees C) were quantified by growth delay. The time to reach five times the volume at the time of treatment after 30 Gy alone was found to be 56.0, 134.9 and 184.0 days for the R3327-AT1, HI and H tumors, respectively. The R3327-H tumor was more radiosensitive than the AT1 or HI subline. Five of nine R3327-H tumors were controlled locally with a single dose of photons (40 Gy). Local tumor hyperthermia alone induced growth delay in both differentiated tumors, while the anaplastic tumor subline did not respond. Combined treatment modalities with heat applied directly after irradiation revealed isoeffective thermal enhancement ratios for 30 Gy which decreased from 1.59 for the AT1 tumor and 1.42 for the HI tumor to 1.23 in the well-differentiated subline R3327-H. (C) 1998 by Radiation Research Society
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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