SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "swepub ;lar1:(umu);conttype:(refereed);srt2:(2000-2004);srt2:(2002);lar1:(su)"

Sökning: swepub > Umeå universitet > Refereegranskat > (2000-2004) > (2002) > Stockholms universitet

  • Resultat 1-3 av 3
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Toma-Dasu, Iuliana, et al. (författare)
  • Theoretical simulation of oxygen tension measurement in the tissue using a microelectrode: II. Simulated measurements in tissues
  • 2002
  • Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 64:1, s. 109-118
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND AND PURPOSE: The objectives of this study were to make a computer simulation of tissues with different vascular structures and to simulate measurements of oxygen tension using an Eppendorf-like electrode in these tissues and to compare the response to radiation of the tissues with the real oxygen distributions (called input distribution) with the response to radiation of the tissues in which the oxygen distribution is given by the results of the simulated measurements (called output distribution).MATERIALS AND METHODS: The structure of various tissues and the measurements of oxygen tension using a microelectrode were simulated using a computer program. The mathematical model used combines the description of a gradient of tissue oxygenation and the electrode absorption process.RESULTS: We have compared the oxygen distributions resulting from diffusion (input) with those obtained from a simulation of measurements (output) for various tissues in the same points. Because the electrode measurement is an averaging process, the calculated oxygen distributions are different from the expected ones and the extreme high and low values are not detected. We have then calculated the survival curves describing the response to radiation if there is a small fraction of truly hypoxic cells (expected values) or a large fraction of cells at intermediate values (observed results) in order to determine the differences between them.CONCLUSIONS: The results of our study show that oxygen electrode measurements do not give the true distribution of pO(2) values in the tissue. However, our results do not contradict the numerous empirical correlations between the Eppendorf measurements of tumour oxygenation and the outcome of treatments. Measurement results will be misleading for modelling purposes since they do not reflect the actual distributions of oxygen tensions in the measured tissue. Decisions based on such modelling could be very dangerous, especially with respect to the clinical response of tumours to new treatments.
  •  
2.
  • Matscheko, Nadja, et al. (författare)
  • Application of sewage sludge to arable land-soil concentrations of polybrominated diphenyl ethers and polychorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls, and their accumulation in earthworms
  • 2002
  • Ingår i: Environmental Toxicology and Chemistry. - 0730-7268 .- 1552-8618. ; 21:12, s. 2515-25
  • Tidskriftsartikel (refereegranskat)abstract
    • Soils from five agricultural sites, three research sites, and two privately owned farms were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polybronimated diphenylethers (PBDEs). In soils that had not been treated with sludge (reference soils), the international toxic equivalents (I-TEQs) were 0.6 to 1.5 pg/g dry matter (DM) for the PCDD/Fs, which are low compared to generally reported background soil levels in Europe. The concentrations of sum of six penta- and hexa-PCBs were 450 to 1,400 pg/g DM. The PBDEs 47 and 99 dominated among the tri- to hepta-PBDEs analyzed (8-80 pg/g DM). The impact of adding 1 to 3 tonnes of sludge (DM) per hectare per year on the concentrations was studied at the three research sites by calculating ratios of the compounds in sludge-treated soil to reference soil (S/R ratio). The concentrations of I-TEQs did not increase in the sludge-treated soil, whereas the S/R ratios for PBDEs were greater than one. Also, although the PCB contents were higher in the sludge-treated soils, the background sources were more important for the concentrations of PCBs than of PBDEs. The largest increase in the S/R ratios was found at a private farm where large amounts of sludge had been used in the past. Accumulation of the compounds in earthworms from the sites also was investigated. The biota-soil accumulation factors (BSAFs) of the tested compounds declined in the following order: ortho-PCBs similar to PBDEs > non-ortho-PCBs > 2,3,7,8-substituted PCDD/Fs. The average BSAF for ortho-PCBs was five (organic matter/lipids), and the lowest BSAFs (0.1-0.8) found were for octachlorodibenzo-p-dioxin. To our knowledge, accumulation of PBDEs in earthworms has not been published previously.
  •  
3.
  • Palm, Anna, et al. (författare)
  • Assessing the environmental fate of chemicals of emerging concern: a case study of the polybrominated diphenyl ethers
  • 2002
  • Ingår i: Environmental Pollution. - 0269-7491 .- 1873-6424. ; 117:2, s. 195-213
  • Tidskriftsartikel (refereegranskat)abstract
    • It is suggested that assessments of chemicals of emerging concern can be rationally structured around a multistage process in which fate and risk are evaluated with increasing accuracy as new data become available. An initial tentative and approximate assessment of fate and risk can identify key data gaps and justify and direct further investigations, which progressively improve the reliability of the assessment. This approach is demonstrated for a class of chemicals, the polybrominated diphenyl ethers (PBDEs), which is of increasing concern, but about which there is presently a lack of comprehensive data on properties, sources, fate and effects. Specifically, 20 PBDE congeners are investigated using the suggested approach and research needs are identified.For chemicals of emerging concern, an initial and approximate assessment of fate and risk can identify key data gaps.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-3 av 3
Typ av publikation
tidskriftsartikel (3)
Typ av innehåll
Författare/redaktör
Tysklind, Mats (2)
Toma-Daşu, Iuliana (1)
Cousins, Ian T. (1)
Andersson, Rolf (1)
Bergek, Sture (1)
Dasu, Alexandru (1)
visa fler...
Sellström, Ulla (1)
Alaee, Mehran (1)
de Wit, Cynthia (1)
Waites, Anthony (1)
Fowler, Jack F (1)
Denekamp, Juliana (1)
Metcalfe, Chris (1)
Palm, Anna (1)
Mackay, Donald (1)
Matscheko, Nadja (1)
visa färre...
Lärosäte
Språk
Engelska (3)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (2)
Medicin och hälsovetenskap (1)
År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy