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Träfflista för sökning "WFRF:(Bratt Ola) srt2:(1995-1999)"

Sökning: WFRF:(Bratt Ola) > (1995-1999)

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1.
  • Arvidsson, Per-Ola, et al. (författare)
  • Purification and identification of the violaxanthin de-epoxidase as a 43 kDa protein
  • 1996
  • Ingår i: Photosynthesis Research. - 0166-8595. ; 49:2, s. 119-129
  • Tidskriftsartikel (refereegranskat)abstract
    • Violaxanthin deepoxidase (VDE) has been purified from spinach (Spinacia oleracea) leaves. The purification included differential sonication of thylakoid membranes, differential (NH4)2SO4 fractionation, gel filtration chromatography and finally either hydrophobic interaction chromatography or anion exchange chromatography. A total purification of more than 5000-fold compared to the original thylakoids enabled the identification of a 43 kDa protein as the VDE, in contrast to earlier reported molecular weight of 54–60 kDa. A detailed comparison was made for the VDE activity and polypeptide pattern for the different fractions throughout the purification and the best correlation was always found for the 43 kDa protein. The highest specific activity obtained was 256 mol g–1 s–1 protein, which is at least 10-fold higher than reported earlier. We estimate that there is 1 VDE molecule per 20–100 electron transport chains. The 43 kDa protein was N-terminally sequenced, after protection of cysteine residues with -mercaptoethanol and iodoacetamid, and a unique sequence of 20 amino acids was obtained. The amino acid composition of the protein revealed a high abundance of charged and polar amino acids and remarkably, 11 cysteine residues. Two other proteins (39.5 kDa and 40 kDa) copurifying with VDE were also N-terminally sequenced. The N-terminal part of the 39.5 kDa protein showed complete sequence identity both with the N-terminal part of cyt b 6 and an internal sequence of polyphenol oxidase.
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2.
  • Bratt, Charlotte Eva, et al. (författare)
  • Regulation of violaxanthin de-epoxidase activity by pH and ascorbate concentration
  • 1995
  • Ingår i: Photosynthesis Research. - 0166-8595. ; 45:2, s. 169-175
  • Tidskriftsartikel (refereegranskat)abstract
    • The activity of violaxanthin de-epoxidase has been studied both in isolated thylakoids and after partial purification, as a function of pH and ascorbate concentration. We demonstrate that violaxanthin de-epoxidase has a Km for ascorbate that is strongly dependent on pH, with values of 10, 2.5, 1.0 and 0.3 mM at pH 6.0, 5.5, 5.0 and 4.5, respectively. These values can be expressed as a single Km±0.1±0.02 mM for the acid form of ascorbate. Release of the protein from the thylakoids by sonication was also found to be strongly pH dependent with a cooperativity of 4 with respect to protons and with an inflexion point at pH 6.7. These results can explain some of the discrepancies reported in the literature and provide a more consistent view of zeaxanthin formation in vivo.
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3.
  • Bratt, Ola (författare)
  • Familial and Hereditary Prostate Cancer
  • 1999
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis is based on research concerning epidemiological, clinical, and psychological aspects of familial and hereditary prostate cancer. Epidemiology: Male first-degree relatives of prostate cancer patients had a three-fold increased prostate cancer risk. The risk was higher for relatives of younger patients than for relatives of older patients, most likely due to the effect of the higher prevalence of hereditary prostate cancer found among the former. For first-degree relatives of men with early onset prostate cancer, the risk of developing prostate cancer before the age of 70 years was increased 3.4 times, but their total cancer risk was not increased. Short CAG repeats in the androgen receptor gene correlated with early age at diagnosis of non-hereditary prostate cancer, but not with the risk of developing the disease per se. Clinical aspects: Patients with hereditary prostate cancer were diagnosed, on an average, 7 years earlier than those with sporadic prostate cancer. Family history of prostate cancer was not significantly associated with survival for patients with early onset disease. Psychological aspects: Most men with a family history of prostate cancer worried about the possibility of inheriting the disease. Almost all of them (90-94%) had positive attitudes towards genetic investigations, including genetic testing, and screening. Forty percent of unaffected men in families with hereditary prostate cancer substantially overestimated their lifetime risk of the disease. Perception of high risk was associated with symptoms of depression and cancer worries that affected daily living. High levels of cancerspecific stress may have counteracted participation in screening for some men.
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4.
  • Bratt, Ola, et al. (författare)
  • Metaphase cytogenetics and DNA flow cytometry with analysis of S-phase fraction in prostate cancer: influence on prognosis
  • 1996
  • Ingår i: Urology. - 1527-9995. ; 47:2, s. 218-224
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: To compare the prognostic significance of chromosome aberrations, DNA ploidy, and S-phase fraction (SPF) in prostate adenocarcinomas and to compare the sensitivity of metaphase cytogenetics with flow cytometry (FCM) in detecting abnormal tumor clones. METHODS: Prostate adenocarcinomas from 57 men were previously successfully analyzed with metaphase cytogenetics. Archival material from these tumors were further analyzed with FCM for DNA content and SPF. RESULTS: The patients were followed for 4.5 to 7.7 years. DNA ploidy was analyzed in 51, and SPF in 45 of the 57 tumors. Clonal chromosomal aberrations, DNA aneuploidy, and high SPF were all significantly associated with poor survival. Of these three variables, SPF was the best predictor of survival, but compared with tumor stage and grade in multivariate analysis, SPF was not an independent prognostic factor. Patients with locally advanced tumors or metastatic disease with SPF less than 8% had a median survival of 5.9 years, compared with only 1.3 years for those with SPF more than 8%. Twenty-eight abnormal clones were detected with FCM and 20 with cytogenetic analysis, but only for two of these clones could the results from the two different methods be regarded as concordant. CONCLUSIONS: SPF was superior to karyotype and ploidy in predicting death in prostate cancer, but it remains to be shown whether SPF analysis adds prognostic information to tumor stage and grade. The cytogenetic analyses correlated poorly with results of FCM, indicating low sensitivity of both methods.
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