| 1. |
- Bjohle, J, et al.
(författare)
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Serum thymidine kinase activity compared with CA 15-3 in locally advanced and metastatic breast cancer within a randomized trial
- 2013
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Ingår i: Breast Cancer Research and Treatment. - : Springer Verlag (Germany). - 0167-6806 .- 1573-7217. ; 139:3, s. 751-758
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Tidskriftsartikel (refereegranskat)abstract
- The primary objective was to estimate serum thymidine kinase 1 (TK1) activity, reflecting total body cell proliferation rate including cancer cell proliferation, in women with loco regional inoperable or metastatic breast cancer participating in a prospective and randomized study. Secondary objectives were to analyze TK1 in relation to progression-free survival (PFS), overall survival (OS), therapy response and other tumour characteristics, including CA 15-3, widely used as a standard serum marker for disease progression. TK1 and CA 15-3 were analysed in 198 serum samples collected prospectively from women included in the randomized TEX trial between December 2002 and June 2007. TK1 activity was determined by the ELISA based DiviTum (TM) assay, and CA 15-3 analyses was generated with the electrochemiluminescence immunoassay Cobas Elecsys CA 15-3 II. High pre-treatment TK1 activity predicted shorter PFS (10 vs. 15 months p = 0.02) and OS (21 vs. 38 months, p andlt; 0.0001), respectively. After adjustment for age, metastatic site and study treatment TK1 showed a trend as predictor of PFS (p = 0.059) and was an independent prognostic factor for OS, (HR 1.81, 95 % confidence interval (CI) 1.26-2.61, p = 0.001). There was a trend of shortened OS for women with high CA 15-3 (p = 0.054) in univariate analysis, but not after adjustment for the above mentioned covariates. Both TK1 (p = 0.0011) and CA 15-3 (p = 0.0004) predicted response to treatment. There were statistically different distributions of TK1 and CA 15-3 in relation to the site of metastases. TK1 activity measured by DiviTum (TM) predicted therapy response, PFS and OS in loco regional inoperable or disseminated breast cancer. These results suggest that this factor is a useful serum marker. In the present material, a prognostic value of CA 15-3 could not be proven.
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| 6. |
- Neumüller, Magnus, et al.
(författare)
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HIV reverse transcriptase inhibiting antibodies detected by a new technique : relation to p24 and gp41 antibodies, HIV antigenemia and clinical variables.
- 1991
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Ingår i: Journal of Medical Virology. - : Wiley. - 0146-6615 .- 1096-9071. ; 34:1, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- A new assay for HIV reverse transcriptase activity inhibiting antibodies (RTI-ab) was used for the analysis of a large collection of sera sampled before and after confirmation of HIV infection. In this assay HIV-RT was preincubated with diluted serum, after which residual RT activity was determined by a technique using a template coupled to macrobeads and 125I-lodo-deoxyuridine-triphosphate as the tracer-substrate. Of the 936 sera analysed, 818 were found positive for RTI-ab, and 824 were positive in Western blot (Wb). The prevalence of RTI-ab compared to Wb was therefore 99.3%. The corresponding figure for 930 sera analysed for envelope-ab, i.e., gp41-ab, was 823 positive, and of these 930 sera 815 were Wb positive, giving a comparative prevalence of 101%. In contrast, only 678 samples of 993 analyzed for core ab, i.e., p24, were positive, giving a prevalence of 77.0% as 880 of these samples were Wb positive. Thus, RTI-ab was as prevalent as gp41-ab, and although the analyses of RTI-ab amounts in different stages showed decreasing levels in stage IV compared to stages II or III, all of the sera except 1 were found positive in stages III and IV. Further, it was found that both the few RTI-ab negative samples in stage II and the few RTI-ab positive samples among Wb negative sera were sampled in connection with seroconversion. The specificity of the RTI-ab assay was 100% in a test of 200 serum samples from HIV negative blood donors. It was concluded that RTI-ab analyses can be made highly sensitive and specific and useful for studies of HIV infection.
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| 7. |
- Nisman, Benjamin, et al.
(författare)
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Circulating Tumor M2 Pyruvate Kinase and Thymidine Kinase 1 Are Potential Predictors for Disease Recurrence in Renal Cell Carcinoma After Nephrectomy
- 2010
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Ingår i: Urology. - : Elsevier BV. - 0090-4295 .- 1527-9995. ; 76:2, s. 513.e1-
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES Pyruvate kinase type M2 (TuM2-PK) and thymidine kinase 1 (TK1) are the key enzymes involved in tumor cells metabolism and proliferation. We explored the association of their preoperative circulating levels with disease recurrence in patients with renal cell carcinoma (RCC). METHODS We measured the plasma levels of TuM2-PK levels and serum TK1 activity preoperatively in patients with RCC, using a quantitative ELISA, and correlated the results with clinicopathological parameters. RESULTS Significantly higher levels of TuM2-PK and TK1 were found in 116 patients with RCC compared with 20 healthy participants (P < .001 and P = .03), but not compared with 27 patients with benign kidney tumors (P = .13 and P = .72). There was a significant association between the level of TuM2-PK and of TK1 activity with T stage (P = .01 and P = .04). Of 2 markers only TuM2-PK was significantly associated with tumor grade (P = .001). The presence of extensive tumor necrosis (> 50%) was associated with high TuM2-PK (P = .001) and low TK1 (P = .03). The 5-year recurrence-free survival for patients with elevated TuM2-PK or TK1 was significantly lower compared with those for patients with normal marker levels (55% vs 94%, P < .001 and 21% vs 90%, P = .002). Multivariate Cox Proportional Hazard analysis demonstrated that TuM2-PK and TK1, adjusted for stage, grade and tumor necrosis were retained as independent predictors of disease recurrence (HR = 7.3, P = .04 and HR = 3.8, P = .03). CONCLUSIONS The measurements of 2 circulating biomarkers, TuM2-PK and TK1, in RCC patients before nephrectomy can be useful for predicting recurrence and stratifying the patients into risk groups for possible adjuvant treatment.
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| 8. |
- Nisman, Benjamin, et al.
(författare)
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Comparison of diagnostic and prognostic performance of two assays measuring thymidine kinase 1 activity in serum of breast cancer patients
- 2013
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Ingår i: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter GmbH. - 1434-6621 .- 1437-4331. ; 51:2, s. 439-447
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Tidskriftsartikel (refereegranskat)abstract
- Background: We compared two recently developed immuno assays for serum thymidine kinase 1 (TK1) activity: one manual assay (DiviTum, Biovica (R)) and one fully automated assay (Liaison, Diasorin (R)). Methods: The study included 368 women: 149 healthy blood donors (control), 59 patients with benign breast disease (BBD) and 160 patients with primary breast cancer (BC). Results: A regression analysis of the Liaison (y) and DiviTum (x) assays for all three groups yielded the equation y=3.93+0.03x (r=0.85, n=368). The r-value in BC was higher than in control and BBD (0.90 vs. 0.81 and 0.64). The correlation between the two assays for TK1 values above the cut-off was higher compared to that below (0.88 and 0.59). Breakdown of the BBD group into subgroups with proliferative and non-proliferative lesions was effective only with the measurement of TK1 with DiviTum assay (p=0.03). The TK1 activity determined preoperatively in BC patients with DiviTum and Liaison assays was significantly associated with T-stage (for both p=0.01), presence of vascular invasion (p=0.002 and p=0.02), lack of estrogen receptor (ER) (p=0.001 and p=0.01) and progesterone receptor (PR) (p=0.01 and p=0.03) expression. Only TK1 analyzed with the DiviTum assay was associated with tumor grade and molecular subtype of BC (p=0.02 and p=0.003). Multivariate Cox proportional hazards analyses demonstrated that T-stage, PR status and TK1 activity measured by both methods (DiviTum, RR=3.0, p=0.02 and Liaison, RR=3.1, p=0.01) were independent predictors of disease recurrence. Conclusions: In spite of differences observed between TK1 activity measured by the DiviTum and Liaison assays, both of them may be used for recurrence prediction in preoperative evaluation of BC patients.
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| 10. |
- Nisman, Benjamin, et al.
(författare)
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Increased Proliferative Background in Healthy Women with BRCA1/2 Haploinsufficiency Is Associated with High Risk for Breast Cancer
- 2013
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - 1055-9965 .- 1538-7755. ; 22:11, s. 2110-2115
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies indicated that BRCA haploinsufficiency was associated with activation of the EGF receptor (EGFR) signaling pathway and increased proliferative activity in mammary epithelial cells of healthy women. We hypothesized that these processes might be reflected in the expression of serologic soluble EGFR (sEGFR) and thymidine kinase 1 (TK1) activity, which signal the initial and final steps of the proliferative pathway, respectively. We found that healthy carriers of BRCA1/2 mutations (n = 80) showed a significantly higher TK1 activity than age-matched controls (P = 0.0003), and TK1 activity was similar in women with BRCA1 and BRCA2 mutations (P = 0.74). The sEGFR concentration was significantly higher in women with BRCA1 than in controls and BRCA2 mutation (P = 0.013 and 0.002, respectively). During follow-up, four of 80 BRCA1/2 mutation carriers developed breast cancer. These women showed a significantly higher TK1 activity and somewhat higher sEGFR concentrations than the other 76 BRCA1/2 carriers (P = 0.04 and 0.09, respectively). All tumors were negative for ovarian hormone receptors, but showed a high EGFR expression. This study was limited by the short-term follow-up (mean, 27 months; range, 5-45), which resulted in a small sample size. Women with BRCA1 and BRCA2 mutations that had undergone risk-reducing bilateral salpingo-oophorectomy (BSO) showed significantly lower sEGFR compared with those without surgery (P = 0.007 and 0.038, respectively). Larger, prospective studies are warranted to investigate whether TK1 and sEGFR measurements may be useful for identifying healthy BRCA1/2 carriers with high risk of developing breast cancer; moreover, sEGFR measurements may serve as effective tools for assessing risk before and after BSO.
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| 12. |
- Nisman, Benjamin, et al.
(författare)
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Serum thymidine kinase 1 activity in breast cancer
- 2010
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Ingår i: Cancer Biomarkers. - 1574-0153. ; 7:2, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Thymidine kinase 1 (TK1) is an enzyme involved in DNA synthesis and an important proliferation marker. We explored the association of preoperative serum TK1 activity with clinicopathological parameters and prognosis in terms of recurrence-free survival (RFS) in breast cancer (BC) patients. Patients and methods: TK1 activity in serum of 120 healthy women and 161 BC patients was measured by quantitative ELISA. Results: Serum TK1 activity in BC patients was significantly higher than in healthy women (P < 0.0001). In BC patients elevated TK1 activity was significantly associated with advanced T stage (P = 0.015), higher grade (P = 0.013), presence of tumor necrosis (P = 0.006), vascular invasion (P = 0.002), and lack of estrogen receptor (ER) and progesterone receptor (PR) expression (P = 0.0004 and P = 0.003). Higher TK1 activity was found in patients with BRCA1/2 mutations compared to those without the mutation (P = 0.004). Multivariate Cox proportional hazards analyses demonstrated that TK1, adjusted for stage, grade, necrosis, ER and PR negativity was retained as an independent predictor of disease recurrence (Hazard Ratio = 3.9, 95%CI 1.3-11.6, P = 0.013). Conclusion: Elevated serum TK1 is an important risk factor indicating a high proliferation potential of tumors at the time of excision. In multivariate analysis TK1 activity was found to be an independent prognostic factor for RFS.
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| 13. |
- Nisman, Benjamin, et al.
(författare)
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Serum Thymidine Kinase 1 Activity in the Prognosis and Monitoring of Chemotherapy in Lung Cancer Patients : A Brief Report
- 2014
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Ingår i: Journal of Thoracic Oncology. - 1556-0864 .- 1556-1380. ; 9:10, s. 1568-1572
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Thymidine kinase 1 (TK1) is a metabolic enzyme involved in DNA synthesis. Most standard treatment protocols for lung cancer (LC) include cytotoxic agents, which are potential modulators of TK1. We aimed to assess the prognostic significance of serum TK1 activity and its role in monitoring chemotherapy in LC patients. Methods: TK1 activity was measured using the DiviTum (Biovica) assay in sera from 233 patients with non-small-cell lung cancer (NSCLC), 91 with small-cell lung cancer (SCLC), and 90 with benign lung disease. Results: TK1 activity was significantly associated with age, performance status, and stage in NSCLC and with stage and weight loss in SCLC. In multivariate analysis, pretreatment TK1 activity, adjusted for performance status, stage, and weight loss, independently affected survival in NSCLC (relative risk = 1.45, p = 0.031) and SCLC (relative risk = 2.49, p = 0.001). In NSCLC patients, adjusted elevated TK1 activity (>100 Du/L) at pretreatment was a significant predictor of treatment failure (odds ratio = 2.55, p = 0.01). A small (less than twofold) increase in TK1 activity after the first and second cycle of chemotherapy was significantly associated with treatment failure and poor overall survival. Conclusions: Elevated pretreatment serum TK1 activity was an independent, adverse prognostic factor, based on survival, in the two main histological types of LC. A small (less than twofold) increase in TK1 activity after the first and second cycle of chemotherapy was associated with treatment failure and poor overall survival.
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| 14. |
- Sauerbrei, A., et al.
(författare)
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Screening of herpes simplex virus type 1 isolates for acyclovir resistance using DiviTum® assay
- 2013
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Ingår i: Journal of Virological Methods. - : Elsevier BV. - 0166-0934 .- 1879-0984. ; 188:1-2, s. 70-72
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Tidskriftsartikel (refereegranskat)abstract
- Rapid alternative methods are required to evaluate easily acyclovir (ACV) sensitivity of clinical herpes simplex virus (HSV) isolates. The objective of this study was to screen 54 ACV-sensitive and 41 ACV-resistant clinical HSV-1 isolates, well characterized by phenotypic and genotypic methods, for the phosphorylation activity of the viral thymidine kinase (TK) using a commercially available and modified non-radioactive DiviTum® test on the basis of an indirect enzyme linked immunosorbent assay. The ACV-sensitive HSV-1 isolates had high TK activity values between 31.5±6.4 DiviTum® Units per liter (DU/L) and 487.4±60.1DU/L. The mean activity of all ACV-sensitive isolates was calculated as 212.3±15.7 DU/L. By contrast, the mean activity of all ACV-resistant HSV-1 isolates was significantly lower at 5.5±1.3DU/L. Out of the 41 ACV-resistant HSV-1 isolates, 38 had no or very low phosphorylation activities of the viral TK between 0DU/L and 9.3±3.2DU/L. The remaining three ACV-resistant viral isolates had TK activities between 44.6±5.1DU/L and 80.9±13.3DU/L. In conclusion, the modified DiviTum® test can be used to screen HSV-1 isolates for their sensitivity to ACV. Acyclovir-sensitive HSV-1 isolates show TK activities >30DU/L and ACV-resistant isolates have activity values <10DU/L. However, single ACV-resistant HSV-1 isolates can have TK activity values >30DU/L. These strains are most likely ACV-resistant TK-altered mutants, but no evidence was provided for an alteration of the TK.
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| 15. |
- Shao, X-W, et al.
(författare)
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Application of a colorimetric chain-termination assay for characterization of reverse transcriptase from 3-azido-2,3-deoxythymidine-resistant HIV isolates
- 2002
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Ingår i: Biotechnology and applied biochemistry. - 0885-4513 .- 1470-8744. ; 35, s. 155-164
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Tidskriftsartikel (refereegranskat)abstract
- wo different enzyme assays, both based on the interaction of native reverse transcriptase(IRT) and 3'-azido-2',3'-deoxythymidine triphosphate (AZT-TP), were used to characterize the enzymesfrom 18 HIV-I isolates with decreased sensitivity to AZT in cell culture. The first assay, which measures the balance between incorporation and excision of AZT monophosphate in the presence of dNTP substrate (in terms of IC50), gave an approx. 9-fold variation in sensitivity to AZT-TP. There was a correlation between the IC50 values and the sensitivity of the corresponding virus to AZT in cell culture (r = 0.60, P < 0.01). The second assay, which was designed specifically for measurement of chain termination in the absence of dNTP substrate (as the concentration of AZT-TP giving 50% residual primer function, or CT50), revealed a more than 600-fold difference between the different isolate RTs. For the majority ofenzymes there was a strict correlation between the results from the two assays; however, four isolatesexhibited significantly higher CT50/IC50 ratios than the other isolates. These differences were not related to sensitivity of the corresponding viruses to AZT but to the occurrence of certain mutations in their pol gene. The four deviating isolates contained either a minimum of four AZT-specific substitutions, including Thr-215 --> Tyr (isolates 134 and 143), or some of the known specific substitutions combined with Thr-39 --> Ala (isolates 80 and 157). The Thr-39 Ala substitution has previously been recorded in connection with AZT/Foscarnet combination therapy.
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| 16. |
- Shao, Xing-Wu, et al.
(författare)
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Use of HIV-1 reverse transcriptase recovered from human plasma for phenotypic drug susceptibility testing
- 2003
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Ingår i: AIDS. ; 17, s. 1463-1471
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To demonstrate the use of HIV-1 reverse transcriplase (RT) recovered directly fromplasma for phenotypic drug susceptibility testing. Methods: Plasma from HIV-1 infected individuals with and without drug resistance-associated mutations were selected for the study. The blind coded plasmas were treated to inactivate cellular enzymes. The virions were immobilized on a gel and washed to remove antiretroviral drugs and RT activity blocking antibodies. The immobilized virions were lysed; the viral RTeluted and quantified, all according to the ExaVir Load procedure. The drug sensitivity profiles of each RT were determined using serially diluted drugs and modified Cavidi HS Lenti RT kits. Results: The phenotypic drug sensitivity profiles of the RT and the patterns of drug resistance mutations were highly concordant. Plasma RT from virions devoid of mutations associated with drug resistance had average 50% inhibitory concentrations (IC50) of 1.5 +/- 0.93 muM for nevirapine, 0.21 +/- 0.099 muM forefavirenz, 7.1 +/- 3.2 muM for delavirdine, 0.42 +/- 0.15 muM for azidothymidine triphosphate and 0.059 +/- 0.018 muM for didehydrothymidine triphosphate. The increase in IC50 value for RT with drugresistance associated substitutions was from 3- to more than 65-fold for non-nucleoside inhibitors and between 2- and 30-fold for thymidine analogue drugs. Conclusion: RT derived from virions recovered from the plasma of HIV infected individuals can be used foranalysis of phenotypic drug susceptibility. The methods presented provide rapid alternatives for analysingphenotypic drug susceptibility especially when the therapy is based on non-nucleoside RT inhibitors and thymidine-analogue drugs.
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