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- Kvitne, K. E., et al.
(författare)
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Correlations between 4 beta-hydroxycholesterol and hepatic and intestinal CYP3A4: protein expression, microsomal ex vivo activity, and in vivo activity in patients with a wide body weight range
- 2022
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Ingår i: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 0031-6970 .- 1432-1041. ; 78:8, s. 1289-1299
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Variability in cytochrome P450 3A4 (CYP3A4) metabolism is mainly caused by non-genetic factors, hence providing a need for accurate phenotype biomarkers. Although 4 beta-hydroxycholesterol (4 beta OHC) is a promising endogenous CYP3A4 biomarker, additional investigations are required to evaluate its ability to predict CYP3A4 activity. This study investigated the correlations between 4 beta OHC concentrations and hepatic and intestinal CYP3A4 protein expression and ex vivo microsomal activity in paired liver and jejunum samples, as well as in vivo CYP3A4 phenotyping (midazolam) in patients with a wide body weight range. Methods The patients (n = 96; 78 with obesity and 18 normal or overweight individuals) were included from the COCKTAIL-study (NCT02386917). Plasma samples for analysis of 4 beta OHC and midazolam concentrations, and liver (n = 56) and jejunal (n = 38) biopsies were obtained. The biopsies for determination of CYP3A4 protein concentration and microsomal activity were obtained during gastric bypass or cholecystectomy. In vivo CYP3A4 phenotyping was performed using semi-simultaneous oral (1.5 mg) and intravenous (1.0 mg) midazolam. Results 4 beta OHC concentrations were positively correlated with hepatic microsomal CYP3A4 activity (rho = 0.53, p < 0.001), and hepatic CYP3A4 concentrations (rho = 0.30, p = 0.027), but not with intestinal CYP3A4 concentrations (rho = 0.18, p = 0.28) or intestinal microsomal CYP3A4 activity (rho = 0.15, p = 0.53). 4 beta OHC concentrations correlated weakly with midazolam absolute bioavailability (rho = - 0.23, p = 0.027) and apparent oral clearance (rho = 0.28, p = 0.008), but not with systemic clearance (rho = - 0.03, p = 0.81). Conclusion These findings suggest that 4 beta OHC concentrations reflect hepatic, but not intestinal, CYP3A4 activity. Further studies should investigate the potential value of 4 beta OHC as an endogenous biomarker for individual dose requirements of intravenously administered CYP3A4 substrate drugs.
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- Kvitne, K. E., et al.
(författare)
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Short- and long-term effects of body weight loss following calorie restriction and gastric bypass on CYP3A-activity - a non-randomized three-armed controlled trial
- 2022
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Ingår i: Cts-Clinical and Translational Science. - : Wiley. - 1752-8054 .- 1752-8062. ; 15:1, s. 221-233
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Tidskriftsartikel (refereegranskat)abstract
- It remains uncertain whether pharmacokinetic changes following Roux-en-Y gastric bypass (RYGB) can be attributed to surgery-induced gastrointestinal alterations per se and/or the subsequent weight loss. The aim was to compare short- and long-term effects of RYGB and calorie restriction on CYP3A-activity, and cross-sectionally compare CYP3A-activity with normal weight to overweight controls using midazolam as probe drug. This three-armed controlled trial included patients with severe obesity preparing for RYGB (n = 41) or diet-induced (n = 41) weight-loss, and controls (n = 18). Both weight-loss groups underwent a 3-week low-energy-diet (<1200 kcal/day) followed by a 6-week very-low-energy-diet or RYGB (both <800 kcal/day). Patients were followed for 2 years, with four pharmacokinetic investigations using semisimultaneous oral and intravenous dosing to determine changes in midazolam absolute bioavailability and clearance, within and between groups. The RYGB and diet groups showed similar weight-loss at week 9 (13 +/- 2.4% vs. 11 +/- 3.6%), but differed substantially after 2 years (-30 +/- 7.0% vs. -3.1 +/- 6.3%). At baseline, mean absolute bioavailability and clearance of midazolam were similar in the RYGB and diet groups, but higher compared with controls. On average, absolute bioavailability was unaltered at week 9, but decreased by 40 +/- 7.5% in the RYGB group and 32 +/- 6.1% in the diet group at year 2 compared with baseline, with no between-group difference. No difference in clearance was observed over time, nor between groups. In conclusion, neither RYGB per se nor weight loss impacted absolute bioavailability or clearance of midazolam short term. Long term, absolute bioavailability was similarly decreased in both groups despite different weight loss, suggesting that the recovered CYP3A-activity is not only dependent on weight-loss through RYGB.
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- Lindström, Björn, et al.
(författare)
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Results of UFO dynamics studies with beam in the LHC
- 2018
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 1067:2
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Tidskriftsartikel (refereegranskat)abstract
- Micrometer sized particles entering the LHC beam (the so called Unidentified Falling Objects or UFOs) are a known cause of localized beam losses since the beginning of high intensity beam operation, however the origin of these particles is not fully known. Their effect limits LHC availability by causing premature dumps due to excessive beam losses and occasionally even magnet quenches. This could become an important limitation for future accelerators such as the High Luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC). The dynamics of these UFOs was investigated in two dedicated experiments. In the first experiment, it was shown that the transverse movements of these particles can be studied by observing bunch-by-bunch losses from bunches with different horizontal and vertical emittances. In the second experiment, UFO-like events around the 16L2 interconnect in the LHC, which has seen intense UFO activity in 2017, were studied with the above method. This paper summarizes the results of both experiments.
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- Ranke, M. B., et al.
(författare)
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Major determinants of height development in Turner syndrome (TS) patients treated with GH: analysis of 987 patients from KIGS
- 2007
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Ingår i: Pediatr Res. - : Springer Science and Business Media LLC. - 0031-3998. ; 61:1, s. 105-10
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about factors determining height outcome during GH treatment in Turner syndrome (TS). We investigated 987 TS children within the Kabi International Growth Study (KIGS) who had reached near adult height (NAH) after >4 y GH treatment (including >1 y before puberty). Through multiple regression analysis we developed a model for NAH and total gain. Our results were as follows (median): 1) At start, age 9.7 yrs, height (HT) 118.0 cm (0.0 TS SDS), projected adult height 146.1 cm, GH dose 0.27 mg/kg wk; 2) NAH HT 151.0 cm (1.5 TS SDS); 3) Prepubertal gain 21.2 cm (1.6 TS SDS); 4) Pubertal gain 9.4 cm (0.0 TS SDS). NAH correlated (r = 0.67) with (ranked) HT at GH start (+), 1 year responsiveness to GH (+), MPH (+), age at puberty onset (+), age at GH start (-), and dose (+). The same factors explained (R = 0.90) the total HT gain. However, HT at GH start correlated negatively. Karyotype had no influence on outcome. Evidently, height at GH start (the taller, the better), age at GH start (the younger, the better), the responsiveness to GH (the higher, the better) and age at puberty (the later, the better) determine NAH.
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