24 results on '"Buijs D"'
Search Results
2. 3-dimensional ct versus angiography guided pci for ostial rca lesions
- Author
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Van Den Buijs, D M F, primary, Poels, E M, additional, Willems, E, additional, Cottens, D, additional, Ferdinande, B, additional, Vrolix, M, additional, Dens, J, additional, and Ameloot, K, additional
- Published
- 2023
- Full Text
- View/download PDF
3. What can a media privilege look like? Unpacking three versions in the EMFA.
- Author
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van Drunen, M. Z., Papaevangelou, C., Buijs, D., and Fathaigh, R. Ó.
- Subjects
BUILDING commissioning - Abstract
The media privilege has been one of the most controversial aspects of the proposed European Media Freedom Act (EMFA). However, it is important not to assess the drawbacks of the media privilege in isolation, but in relation to the other available alternatives. In this comment, we lay out and critique how the European Parliament and Council build on the Commission's proposal for a media privilege in the EMFA. We focus on three key questions: how is media content treated differently, who qualifies as media, and who decides who qualifies as media? [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. P132Mitral valve blood cyst: case illustration from imaging diagnosis to surgical removal with review of current literature
- Author
-
Van Den Buijs, D M F, primary, Kolff, A Q, additional, and Huijbregts, M A J M, additional
- Published
- 2019
- Full Text
- View/download PDF
5. Infective endocarditis in the Netherlands: current epidemiological profile and mortality: An analysis based on partial ESC EORP collected data.
- Author
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El Kadi, S., van den Buijs, D. M. F., Meijers, T., Gilbers, M. D., Bekkers, S. C. A. M., van Melle, J. P., Riezebos, R. K., Blok, W. L., Tanis, W., Wahadat, A. R., Roos-Hesselink, J. W., van der Spoel, T. I. G., Chamuleau, S. A. J., and Kamp, O.
- Subjects
INFECTIVE endocarditis ,MORTALITY ,ENDOCARDITIS ,HEART failure ,FLUORODEOXYGLUCOSE F18 - Abstract
Introduction: Infective endocarditis (IE) is associated with a high in-hospital and long term mortality. Although progress has been made in diagnostic approach and management of IE, morbidity and mortality of IE remain high. In the latest European guidelines, the importance of the multi-modality imaging in diagnosis and follow up of IE is emphasized. Aim: The aim was to provide information regarding mortality and adverse events of IE, to determine IE characteristics and to assess current use of imaging in the diagnostic workup of IE. Methods: This is a prospective observational cohort study. We used data from the EURO-ENDO registry. Seven hospitals in the Netherlands have participated and included patients with IE between April 2016 and April 2018. Results: A total of 139 IE patients were included. Prosthetic valve endocarditis constituted 32.4% of the cases, cardiac device related IE 7.2% and aortic root prosthesis IE 3.6%. In-hospital mortality was 14.4% (20 patients) and one-year mortality was 21.6% (30 patients). The incidence of embolic events under treatment was 16.5%, while congestive heart failure or cardiogenic shock occurred in 15.1% of the patients. Transthoracic and transoesophageal echocardiography were performed most frequently (97.8%; 81.3%) and within 3 days after IE suspicion, followed by
18 F‑fluorodeoxyglucose positron emission tomography/computed tomography (45.3%) within 6 days and multi-slice computed tomography (42.4%) within 7 days. Conclusion: We observed a high percentage of prosthetic valve endocarditis, rapid and extensive use of imaging and a relatively low in-hospital and one-year mortality of IE in the Netherlands. Limitations include possible selection bias. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
6. RELATIONSHIP BETWEEN BREAKS IN SEDENTARY BEHAVIOR AND FREE LIVING PHYSICAL ACTIVITY ENERGY EXPENDITURE IN INDIVIDUALS WITH CORONARY ARTERY DISEASE
- Author
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Ramadi, A., primary, Buijs, D., additional, and Haennel, R., additional
- Published
- 2018
- Full Text
- View/download PDF
7. Stability of corticosteroids under anaerobic conditions: III. 17-ketosteroid
- Author
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Dekker, D. and Buijs, D. J.
- Published
- 1980
- Full Text
- View/download PDF
8. Volume and patterns of physical activity in heart failure patients
- Author
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Yavari, M., primary, Buijs, D., additional, Haykowsky, M., additional, Podder, M., additional, Irwin, M., additional, Dyck, J., additional, and Haennel, R., additional
- Published
- 2015
- Full Text
- View/download PDF
9. Influence of Cremophor EL on the bioavailability of intraperitoneal paclitaxel
- Author
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Gelderblom, AJ, Verweij, Jaap, Boven - van Zomeren, DM, Buijs, D, Ouwens, L, Nooter, K (Kees), Stoter, Gerrit, Sparreboom, A, and Medical Oncology
- Published
- 2002
10. De eenzijdige wijziging van een contract
- Author
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Tjittes, R.P.J.L., Buijs, D., Dutch Private Law, and Research Programmes - Law
- Published
- 2002
11. Influence of Cremophor El on the bioavailability of intraperitoneal paclitaxel
- Author
-
Gelderblom, A.J. (Hans), Verweij, J. (Jaap), Zomeren, D.M. (Desirée) van, Buijs, D., Ouwens, L., Nooter, K. (Kees), Stoter, G. (Gerrit), Sparreboom, A. (Alex), Gelderblom, A.J. (Hans), Verweij, J. (Jaap), Zomeren, D.M. (Desirée) van, Buijs, D., Ouwens, L., Nooter, K. (Kees), Stoter, G. (Gerrit), and Sparreboom, A. (Alex)
- Abstract
It has been hypothesized that the paclitaxel vehicle Cremophor EL (CrEL) is responsible for nonlinear drug disposition by micellar entrapment. To gain further insight into the role of CrEL in taxane pharmacology, we studied the pharmacokinetics of paclitaxel in the presence and absence of CrEL after i.p. and i.v. dosing. Patients received an i.p. tracer dose of [G-(3)H]paclitaxel in ethanol without CrEL (100 microCi diluted further in isotonic saline) on day 1, i.p. paclitaxel formulated in CrEL (Taxol; 125 mg/m(2)) on day 4, an i.v. tracer of [G-(3)H]paclitaxel on day 22, and i.v. Taxol (175 mg/m(2)) on day 24. Four patients (age range, 54-74 years) were studied, and serial plasma samples up to 72 h were obtained and analyzed for total radioactivity, paclitaxel, and CrEL. In the presence of CrEL, i.v. paclitaxel clearance was 10.2 +/- 3.76 liters/h/m(2) (mean +/- SD), consistent with previous findings. The terminal disposition half-life was substantially prolonged after i.p. dosing (17.0 +/- 11.3 versus 28.7 +/- 8.72 h), as was the mean residence time (7.28 +/- 2.76 versus 40.7 +/- 13.8 h). The bioavailability of paclitaxel was 31.4 +/- 5.18%, indicating insignificant systemic concentrations after i.p. treatment. CrEL levels were undetectable after i.p. dosing (<0.05 microl/ml), whereas after i.v. dosing, the mean clearance was 159 +/- 58.4 ml/h/m(2), in line with earlier observations. In the absence of CrEL, the bioavailability and systemic concentrations of i.p. paclitaxel were significantly increased. This finding is consistent with the postulated concept that CrEL is largely responsible for the pharmacokinetic advantage for peritoneal cavity exposure to total paclitaxel compared with systemic delivery.
- Published
- 2002
12. Measurement of fraction unbound paclitaxel in human plasma
- Author
-
Brouwer, E. (Eric), Verweij, J. (Jaap), Bruijn, P.J. (Peter) de, Loos, W.J. (Walter), Pillay, M., Buijs, D., Sparreboom, A. (Alex), Brouwer, E. (Eric), Verweij, J. (Jaap), Bruijn, P.J. (Peter) de, Loos, W.J. (Walter), Pillay, M., Buijs, D., and Sparreboom, A. (Alex)
- Abstract
The clinical pharmacokinetic behavior of paclitaxel (Taxol) is distinctly nonlinear, with disproportional increases in systemic exposure with an increase in dose. We have recently shown that Cremophor EL, the formulation vehicle used for i.v. administration of paclitaxel, alters drug distribution as a result of micellar entrapment of paclitaxel, and we speculated that the free drug fraction (fu) is dependent on dose and time-varying concentrations of Cremophor EL in the central plasma compartment. To test this hypothesis, a reproducible equilibrium dialysis method has been developed for the measurement of paclitaxel fu in plasma. Equilibrium dialysis was performed at 37 degrees C in a humidified atmosphere of 5% CO(2) using 2.0-ml polypropylene test tubes. Experiments were carried out with 260-microliter aliquots of plasma containing a tracer amount of [G-(3)H]paclitaxel with high-specific activity against an equal volume of 0.01 M phosphate buffer (pH 7.4). Drug concentrations were measured by both reversed-phase HPLC and liquid scintillation counting. Using this method, fu has been measured in three patients receiving three consecutive 3-weekly courses of paclitaxel at dose levels of 135, 175, and 225 mg/m(2) and found to range between 0.036 and 0.079. The method was also used to define concentration-time profiles of unbound drug, estimated from the product of the total plasma concentration and fu.
- Published
- 2000
13. Measurement of fraction unbound paclitaxel in human plasma
- Author
-
Brouwer, E, Verweij, Jaap, de Bruijn, Peter, Loos, Walter, Pillay, M, Buijs, D, Sparreboom, A, Brouwer, E, Verweij, Jaap, de Bruijn, Peter, Loos, Walter, Pillay, M, Buijs, D, and Sparreboom, A
- Published
- 2000
14. P132 Mitral valve blood cyst: case illustration from imaging diagnosis to surgical removal with review of current literature.
- Author
-
Buijs, D M F Van Den, Kolff, A Q, and Huijbregts, M A J M
- Subjects
CONFERENCES & conventions ,CYSTS (Pathology) ,MITRAL valve - Published
- 2019
- Full Text
- View/download PDF
15. Exclusive production of proton-antiproton pairs in two-photon collisions
- Author
-
Aihara, H., primary, Alston-Garnjost, n M., additional, Avery, a R. E., additional, Barbaro-Galtieri, a A., additional, Barker, a A. R., additional, Barnett, a B. A., additional, Bauer, j D. A., additional, Bengtsson, g H. -U., additional, Bintinger, d D. L., additional, Bobbink, f G. J., additional, Bolognese, h T. S., additional, Bross, a A. D., additional, Buchanan, a C. D., additional, Buijs, d A., additional, Cain, m M. P., additional, Caldwell, b D. O., additional, Clark, g A. R., additional, Cowan, a G. D., additional, Crane, a D. A., additional, Dahl, j O. I., additional, Derby, a K. A., additional, Eastman, a J. J., additional, Eberhard, a P. H., additional, Edberg, a T. K., additional, Eisner, a A. M., additional, Enomoto, c R., additional, Erné, n F. C., additional, Fujii, m T., additional, Gary, n J. W., additional, Gorn, a W., additional, Hauptman, e J. M., additional, Hofmann, i W., additional, Huth, a J. E., additional, Hylen, a J., additional, Kamae, j T., additional, Kaye, n H. S., additional, Kees, a K. H., additional, Kenney, f R. W., additional, Kerth, a L. T., additional, Ko, a Winston, additional, Koda, b R. I., additional, Kofler, d R. R., additional, Kwong, k K. K., additional, Lander, e R. L., additional, Langeveld, b W. G. J., additional, Layter, e J. G., additional, Linde, e F. L., additional, Lindsey, m C. S., additional, Loken, e S. C., additional, Lu, a A., additional, Lu, g X-Q., additional, Lynch, j G. R., additional, Madaras, a R. J., additional, Maeshima, a K., additional, Magnuson, b B. D., additional, Marx, c J. N., additional, Masek, a G. E., additional, Mathis, f L. G., additional, Matthews, a J. A. J., additional, Maxfield, j S. J., additional, Melnikoff, k S. O., additional, Miller, e E. S., additional, Moses, f W., additional, McNeil, a R. R., additional, Nemethy, b P., additional, Nygren, l D. R., additional, Oddone, a P. J., additional, Paar, a H. P., additional, Park, m D. A., additional, Park, d S. K., additional, Pellett, i D. E., additional, Pripstein, b M., additional, Ronan, a M. T., additional, Ross, a R. R., additional, Rouse, a F. R., additional, Schwitkis, a K. A., additional, Sens, g J. C., additional, Shapiro, m G., additional, Shapiro, a M. D., additional, Shen, a B. C., additional, Slater, e W. E., additional, Smith, d J. R., additional, Steinman, b J. S., additional, Stevenson, d M. L., additional, Stork, a D. H., additional, Strauss, d M. G., additional, Sullivan, d M. K., additional, Takahashi, c T., additional, Thompson, n J. R., additional, Toge, f N., additional, Toutounchi, n S., additional, van Tyen, k R., additional, van Uitert, a B., additional, VanDalen, m G. J., additional, van Daalen Wetters, e R. F., additional, Vernon, d W., additional, Wagner, f W., additional, Wang, b E. M., additional, Wang, a Y. X., additional, Wayne, g M. R., additional, Wenzel, d W. A., additional, White, a J. T., additional, Williams, f M. C. S., additional, Wolf, b Z. R., additional, Yamamoto, a H., additional, Yellin, a S. J., additional, Zeitlin, g C., additional, and Zhangj, W-M., additional
- Published
- 1987
- Full Text
- View/download PDF
16. Long-term clinical outcomes of excimer laser coronary atherectomy for the management of recurrent in-stent restenosis.
- Author
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Farag M, van den Buijs D, Loh SX, Poels E, Ameloot K, Janssens L, Bennett J, Tahon J, Dens J, and Egred M
- Subjects
- Humans, Lasers, Excimer therapeutic use, Treatment Outcome, Coronary Angiography, Stents adverse effects, Constriction, Pathologic etiology, Percutaneous Coronary Intervention adverse effects, Atherectomy, Coronary adverse effects, Atherectomy, Coronary methods, Coronary Restenosis diagnosis, Coronary Restenosis etiology, Coronary Restenosis surgery
- Abstract
Background: Recurrent in-stent restenosis (ISR) remains a serious problem. Optimal modification of the underlying mechanism during index percutaneous coronary intervention (PCI) is key to prevent ISR. Excimer laser coronary atherectomy (ELCA) has its own indications and is among others used in recurrent ISR in case of stent underexpansion and/or diffuse neointimal hyperplasia. We aimed to assess the long-term clinical outcomes of ELCA for the management of recurrent ISR., Methods: A multicenter, retrospective observational study was conducted. Patients with recurrent ISR who were additionally treated with ELCA were included. The primary outcome was major adverse cardiac events (MACE) defined as a composite of cardiovascular death, myocardial infarction, stroke, target lesion revascularization at 12 months, and longer term., Results: Between 2014 and 2022, 51 patients underwent PCI with the additional use ELCA for recurrent ISR. Primary outcome occurred in 6 patients (11.8%) at 12 months and in 12 patients (23.5%) at a median follow-up of 4 (1-6) years. Technical and procedural success were achieved in 92% and 90% of cases, respectively. Coronary perforation occurred in 2 patients as a result of distal wire perforation, but was not ELCA-related. There were no in-hospital MACE., Conclusions: ELCA appears to be a safe method with acceptable long-term results for the management of recurrent ISR.
- Published
- 2023
- Full Text
- View/download PDF
17. Giant coronary artery aneurysm of the left main treated with a covered stent: a case report.
- Author
-
Holvoet W, van den Buijs D, Bogaerts E, Willems E, Ameloot K, and Dens J
- Abstract
Background: Coronary artery aneurysms (CAAs) of the left main represent a small subset of coronary artery disease and are associated with cardiovascular death. Because of its rare entity, large data are lacking and therefore treatment guidelines are missing., Case Summary: We describe a case of a 56-year-old female with a past medical history of spontaneous dissection of the distal descending left artery (LAD) 6 years before. She presented to our hospital with a non-ST elevation myocardial infarction and a coronary angiogram showed a giant saccular aneurysm of the shaft of the left main coronary artery (LMCA). Given the risk of rupture and distal embolization, the heart team decided to go for a percutaneous approach. Based on a pre-interventional 3D reconstructed CT scan and guided by intravascular ultrasound, the aneurysm was successfully excluded with a 5 mm papyrus-covered stent. At 3-month and 1-year follow-up, the patient is still asymptomatic and repeat angiographies showed full exclusion of the aneurysm and the absence of restenosis in the covered stent., Discussion: We describe the successful percutaneous IVUS-guided treatment of a giant LMCA shaft coronary aneurysm with a papyrus-covered stent with an excellent 1-year angiographic follow-up showing no residual filling of the aneurysm and no stent restenosis., Competing Interests: Conflict of interest: None declared, (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)
- Published
- 2022
- Full Text
- View/download PDF
18. Postdischarge prognostic significance of periprocedural myocardial injury after percutaneous intervention of chronic total occlusion.
- Author
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Poels E, Vanhaverbeke M, van den Buijs D, Cottens D, Ameloot K, Lesizza P, McCutcheon K, Bennet J, and Dens J
- Subjects
- Humans, Prognosis, Treatment Outcome, Aftercare, Risk Factors, Biomarkers, Time Factors, Patient Discharge, Troponin T, Coronary Occlusion diagnostic imaging, Coronary Occlusion surgery, Percutaneous Coronary Intervention
- Abstract
Background: The postdischarge prognostic implication of periprocedural myocardial injury in patients undergoing percutaneous coronary intervention (PCI) of a chronic total occlusion (CTO) remains scarcely studied., Aims: The aim of this study is to assess the prognostic value of periprocedural myocardial injury, defined by increased high-sensitive troponin T (hs-TnT) levels according to updated guidelines, after CTO PCI., Methods: Between September 2011 and April 2020, 726 patients undergoing CTO PCI at 2 Belgian referral centres were prospectively included and divided into 4 groups based on postprocedural hs-TnT levels (unelevated; ≥5 times the upper limit of normal (ULN); ≥35 times the ULN; ≥70 times the ULN). Postprocedural hs-TnT levels were subsequently related to patient and procedural characteristics, 1-year major adverse cardiac and cerebrovascular events (MACCE; excluding in-hospital MACCE) as well as 1-year mortality., Results: At 1 year follow-up (FU), elevated hs-TnT≥5 times and ≥35 times the ULN were associated with higher MACCE rates (p=0.001; p=0.007, respectively). In addition, they also resulted in a higher 1-year mortality rate (p=0.009;p=0.021, respectively). Patients with increased hs-TnT≥5 times the ULN (35% of patients) more frequently had signs of more advanced atherosclerotic disease (previous CABG p<0.001; stroke p≤0.001 and peripheral vascular disease p<0.001) and had higher procedural complexity (Japanese CTO Score p=<0.001, stent length>48 mm p<0.001, procedure time p<0.001). Antegrade wire escalation did not result in lower event rate of postdischarge MACCE compared with the other CTO crossing techniques combined (p=0.158)., Conclusion: Periprocedural myocardial injury was associated with a significantly higher rate of MACCE and all-cause mortality after 12 months of FU., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2022
- Full Text
- View/download PDF
19. Interactions between the conserved hydrophobic region of the prion protein and dodecylphosphocholine micelles.
- Author
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Sauvé S, Buijs D, Gingras G, and Aubin Y
- Subjects
- Humans, Hydrophobic and Hydrophilic Interactions, Nuclear Magnetic Resonance, Biomolecular, Phosphorylcholine chemistry, Protein Structure, Secondary, Micelles, Peptides chemistry, Phosphorylcholine analogs & derivatives, Prions chemistry
- Abstract
The three-dimensional structure of PrP110-136, a peptide encompassing the conserved hydrophobic region of the human prion protein, has been determined at high resolution in dodecylphosphocholine micelles by NMR. The results support the conclusion that the (Ctm)PrP, a transmembrane form of the prion protein, adopts a different conformation than the reported structures of the normal prion protein determined in solution. Paramagnetic relaxation enhancement studies with gadolinium-diethylenetriaminepentaacetic acid indicated that the conserved hydrophobic region peptide is not inserted symmetrically in the micelle, thus suggesting the presence of a guanidium-phosphate ion pair involving the side chain of the terminal arginine and the detergent headgroup. Titration of dodecylphosphocholine into a solution of PrP110-136 revealed the presence of a surface-bound species. In addition, paramagnetic probes located the surface-bound peptide somewhere below the micelle-water interface when using the inserted helix as a positional reference. This localization of the unknown population would allow a similar ion pair interaction.
- Published
- 2012
- Full Text
- View/download PDF
20. Variation in brain lateralization during various language tasks: a functional transcranial Doppler study.
- Author
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Stroobant N, Buijs D, and Vingerhoets G
- Subjects
- Adolescent, Adult, Brain Mapping, Female, Frontal Lobe physiology, Humans, Male, Task Performance and Analysis, Temporal Lobe physiology, Brain physiology, Functional Laterality physiology, Language, Ultrasonography, Doppler, Transcranial
- Abstract
Language dominance has repeatedly been demonstrated by means of functional transcranial Doppler (fTCD) ultrasonography. However, one strongly lateralizing paradigm might be an overestimation of overall language lateralization. We hypothesized that significant differences between hemodynamic patterns could be shown by using multiple language functions (such as productive and receptive tasks). Particularly, we expected more left-hemispheric activity in frontal and productive tasks and we expected less clear left-hemispheric activity in temporal regions and receptive tasks. Thirty healthy volunteers were included in the study. The lateralization index (LI) was measured with transcranial Doppler ultrasonography for each subject during four language tasks: a cued word generation task (WF), a sentence construction task (SENT), a reading task (READ), and a semantic decision task (SEMANT). Left-hemispheric dominance was found in 90%, 80%, 73.3% and 66.7% of the subjects for respectively WF, SENT, READ and SEMANT. A repeated measures analysis of variance revealed significant differences in LIs between the different language tasks (p<.01). Our results showed that productive and syntactic tasks (WF and SENT) lateralize stronger than receptive tasks (READ and SEMANT). The use of a variety of language tasks in the determination of language lateralization therefore appears to be essential in providing a more comprehensive view of language functioning.
- Published
- 2009
- Full Text
- View/download PDF
21. Quantification of [3H]docetaxel in feces and urine: development and validation of a combustion method.
- Author
-
Engels FK, Buijs D, Loos WJ, Verweij J, Bakker WH, and Krenning EP
- Subjects
- Antineoplastic Agents, Phytogenic administration & dosage, Antineoplastic Agents, Phytogenic pharmacokinetics, Antineoplastic Agents, Phytogenic urine, Docetaxel, Humans, Infusions, Intravenous, Neoplasms drug therapy, Neoplasms metabolism, Reproducibility of Results, Taxoids administration & dosage, Taxoids pharmacokinetics, Taxoids urine, Tritium, Antineoplastic Agents, Phytogenic metabolism, Feces chemistry, Scintillation Counting methods, Taxoids metabolism
- Abstract
Most radiolabeled biological samples require extensive sample preparation to reduce quenching interference before quantification of radioactivity is possible. Clearly, a more rapid and simple method ensuring a constant count rate and optimal counting efficiency has important advantages. We report on the development and analytical method validation of a rapid and simple combustion method to quantify [3H]docetaxel excreted in human feces and urine. A 3-day validation procedure was performed; quality control (QC) samples, prepared in blank feces and urine, were combusted 5 times and aliquots of the produced tritiated combustion water were counted in a liquid scintillation counter. The validation runs demonstrated adequate precision (below 7.6%) across all QC levels. Sensitivity at the lowest QC level was excellent and recovery of radioactivity constant (ranging from 85 to 91.8%). Clinical applicability of the method was tested in a cancer patient receiving docetaxel and a tracer amount of [3H]docetaxel; during the first 72 h after [3H]docetaxel infusion, 60% of total radioactivity was excreted in the collected feces and urine, which is within the expected range. Combustion of tritiated feces and urine samples is a simple, rapid, sensitive, precise and reproducible method with high recovery. It can be applied to quantify [3H]docetaxel excretion after i.v. administration.
- Published
- 2006
- Full Text
- View/download PDF
22. Influence of Cremophor El on the bioavailability of intraperitoneal paclitaxel.
- Author
-
Gelderblom H, Verweij J, van Zomeren DM, Buijs D, Ouwens L, Nooter K, Stoter G, and Sparreboom A
- Subjects
- Aged, Antineoplastic Agents, Phytogenic adverse effects, Antineoplastic Agents, Phytogenic blood, Ascitic Fluid metabolism, Biological Availability, Female, Gastrointestinal Diseases chemically induced, Hematologic Diseases chemically induced, Humans, Injections, Intraperitoneal, Injections, Intravenous, Mesothelioma metabolism, Middle Aged, Ovarian Neoplasms metabolism, Paclitaxel adverse effects, Paclitaxel blood, Antineoplastic Agents, Phytogenic pharmacokinetics, Glycerol analogs & derivatives, Glycerol pharmacology, Mesothelioma drug therapy, Ovarian Neoplasms drug therapy, Paclitaxel pharmacokinetics
- Abstract
It has been hypothesized that the paclitaxel vehicle Cremophor EL (CrEL) is responsible for nonlinear drug disposition by micellar entrapment. To gain further insight into the role of CrEL in taxane pharmacology, we studied the pharmacokinetics of paclitaxel in the presence and absence of CrEL after i.p. and i.v. dosing. Patients received an i.p. tracer dose of [G-(3)H]paclitaxel in ethanol without CrEL (100 microCi diluted further in isotonic saline) on day 1, i.p. paclitaxel formulated in CrEL (Taxol; 125 mg/m(2)) on day 4, an i.v. tracer of [G-(3)H]paclitaxel on day 22, and i.v. Taxol (175 mg/m(2)) on day 24. Four patients (age range, 54-74 years) were studied, and serial plasma samples up to 72 h were obtained and analyzed for total radioactivity, paclitaxel, and CrEL. In the presence of CrEL, i.v. paclitaxel clearance was 10.2 +/- 3.76 liters/h/m(2) (mean +/- SD), consistent with previous findings. The terminal disposition half-life was substantially prolonged after i.p. dosing (17.0 +/- 11.3 versus 28.7 +/- 8.72 h), as was the mean residence time (7.28 +/- 2.76 versus 40.7 +/- 13.8 h). The bioavailability of paclitaxel was 31.4 +/- 5.18%, indicating insignificant systemic concentrations after i.p. treatment. CrEL levels were undetectable after i.p. dosing (<0.05 microl/ml), whereas after i.v. dosing, the mean clearance was 159 +/- 58.4 ml/h/m(2), in line with earlier observations. In the absence of CrEL, the bioavailability and systemic concentrations of i.p. paclitaxel were significantly increased. This finding is consistent with the postulated concept that CrEL is largely responsible for the pharmacokinetic advantage for peritoneal cavity exposure to total paclitaxel compared with systemic delivery.
- Published
- 2002
23. Measurement of fraction unbound paclitaxel in human plasma.
- Author
-
Brouwer E, Verweij J, De Bruijn P, Loos WJ, Pillay M, Buijs D, and Sparreboom A
- Subjects
- Antineoplastic Agents, Phytogenic blood, Antineoplastic Agents, Phytogenic metabolism, Binding, Competitive drug effects, Dose-Response Relationship, Drug, Female, Glycerol administration & dosage, Humans, Male, Metabolic Clearance Rate, Middle Aged, Paclitaxel blood, Paclitaxel metabolism, Plasma metabolism, Antineoplastic Agents, Phytogenic pharmacokinetics, Glycerol analogs & derivatives, Paclitaxel pharmacokinetics
- Abstract
The clinical pharmacokinetic behavior of paclitaxel (Taxol) is distinctly nonlinear, with disproportional increases in systemic exposure with an increase in dose. We have recently shown that Cremophor EL, the formulation vehicle used for i.v. administration of paclitaxel, alters drug distribution as a result of micellar entrapment of paclitaxel, and we speculated that the free drug fraction (fu) is dependent on dose and time-varying concentrations of Cremophor EL in the central plasma compartment. To test this hypothesis, a reproducible equilibrium dialysis method has been developed for the measurement of paclitaxel fu in plasma. Equilibrium dialysis was performed at 37 degrees C in a humidified atmosphere of 5% CO(2) using 2.0-ml polypropylene test tubes. Experiments were carried out with 260-microliter aliquots of plasma containing a tracer amount of [G-(3)H]paclitaxel with high-specific activity against an equal volume of 0.01 M phosphate buffer (pH 7.4). Drug concentrations were measured by both reversed-phase HPLC and liquid scintillation counting. Using this method, fu has been measured in three patients receiving three consecutive 3-weekly courses of paclitaxel at dose levels of 135, 175, and 225 mg/m(2) and found to range between 0.036 and 0.079. The method was also used to define concentration-time profiles of unbound drug, estimated from the product of the total plasma concentration and fu.
- Published
- 2000
24. Response competition and condition competition in visual selective attention.
- Author
-
van der Heijden AH, La Heij W, Phaf RH, Buijs DA, and van Vliet EC
- Subjects
- Adult, Discrimination Learning, Female, Humans, Male, Attention, Color Perception, Form Perception, Pattern Recognition, Visual
- Published
- 1988
- Full Text
- View/download PDF
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