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31.
Determination of nifedipine in human plasma by flow-injection tandem mass spectrometry 总被引:1,自引:0,他引:1
Jan Dankers Jos van den Elshout Gertrude Ahr Erich Brendel Cees van der Heiden 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,710(1-2):115-120
For use in clinical studies, a fast and sensitive assay method was developed for the determination of nifedipine in human plasma samples. The assay method is based on tandem mass spectrometry detection (HPLC–MS–MS). The effect of flow injection as well as HPLC separation on the results of the nifedipine determination were evaluated. The limit of quantification is 0.5 ng/ml and the accuracy (as determined by spiking recovery) was found to be good. 相似文献
32.
Hedde van de Vooren Maaike G J Gademan Cees A Swenne Ben J TenVoorde Martin J Schalij Ernst E Van der Wall 《Journal of applied physiology》2007,102(4):1348-1356
The arterial baroreflex buffers slow (<0.05 Hz) blood pressure (BP) fluctuations, mainly by controlling peripheral resistance. Baroreflex sensitivity (BRS), an important characteristic of baroreflex control, is often noninvasively assessed by relating heart rate (HR) fluctuations to BP fluctuations; more specifically, spectral BRS assessment techniques focus on the BP-to-HR transfer function around 0.1 Hz. Skepticism about the relevance of BRS to characterize baroreflex-mediated BP buffering is based on two considerations: 1) baroreflex-modulated peripheral vasomotor function is not necessarily related to baroreflex-HR transfer; and 2) although BP fluctuations around 0.1 Hz (Mayer waves) might be related to baroreflex BP buffering, they are merely a not-intended side effect of a closed-loop control system. To further investigate the relationship between BRS and baroreflex-mediated BP buffering, we set up a computer model of baroreflex BP control to simulate normal subjects and heart failure patients. Output variables for various randomly chosen combinations of feedback gains in the baroreflex arms were BP resonance, BP-buffering capacity, and BRS. Our results show that BP buffering and BP resonance are related expressions of baroreflex BP control and depend strongly on the sympathetic gain to the peripheral resistance. BRS is almost uniquely determined by the vagal baroreflex gain to the sinus node. In conclusion, BP buffering and BRS are unrelated unless coupled gains in all baroreflex limbs are assumed. Hence, the clinical benefit of a high BRS is most likely to be attributed to vagal effects on the heart instead of to effective BP buffering. 相似文献
33.
34.
Willize E. van der Starre Cees van Nieuwkoop Uginia Thomson Marleen S. M. Zijderveld-Voshart Jan Pieter R. Koopman Tanny J. K. van der Reijden Jaap T. van Dissel Esther van de Vosse 《PloS one》2015,10(3)
Objective/Purpose
Febrile urinary tract infection (UTI) is a common bacterial disease that may lead to substantial morbidity and mortality especially among the elderly. Little is known about biomarkers that predict a complicated course. Our aim was to determine the role of certain urinary cytokines or antimicrobial proteins, plasma vitamin D level, and genetic variation in host defense of febrile UTI and its relation with bacteremia.Methods
A case-control study. Out of a cohort of consecutive adults with febrile UTI (n = 787) included in a multi-center observational cohort study, 46 cases with bacteremic E.coli UTI and 45 cases with non-bacteremic E.coli UTI were randomly selected and compared to 46 controls. Urinary IL-6, IL-8, LL37, β-defensin 2 and uromodulin as well as plasma 25-hydroxyvitamin D were measured. In 440 controls and 707 UTI patients polymorphisms were genotyped in the genes CXCR1, DEFA4, DEFB1, IL6, IL8, MYD88, UMOD, TIRAP, TLR1, TLR2, TLR5 and TNF.Results
IL-6, IL-8, and LL37 are different between controls and UTI patients, although these proteins do not distinguish between patients with and without bacteremia. While uromodulin did not differ between groups, inability to produce uromodulin is more common in patients with bacteremia. Most participants in the study, including the controls, had insufficient vitamin D and, at least in winter, UTI patients have lower vitamin D than controls. Associations were found between the CC genotype of IL6 SNP rs1800795 and occurrence of bacteremia and between TLR5 SNP rs5744168 and protection from UTI. The rare GG genotype of IL6 SNP rs1800795 was associated with higher β-defensin 2 production.Conclusion
Although no biomarker was able to distinguish between UTI with or without bacteremia, two risk factors for bacteremia were identified. These were inability to produce uromodulin and an IL6 rs1800795 genotype. 相似文献35.
36.
Stephanie Nikolaus Christina Bode Erik Taal Harald E. Vonkeman Cees A. W. Glas Mart A. F. J. van de Laar 《PloS one》2015,10(12)
Objective
Multidimensional computerized adaptive testing enables precise measurements of patient-reported outcomes at an individual level across different dimensions. This study examined the construct validity of a multidimensional computerized adaptive test (CAT) for fatigue in rheumatoid arthritis (RA).Methods
The ‘CAT Fatigue RA’ was constructed based on a previously calibrated item bank. It contains 196 items and three dimensions: ‘severity’, ‘impact’ and ‘variability’ of fatigue. The CAT was administered to 166 patients with RA. They also completed a traditional, multidimensional fatigue questionnaire (BRAF-MDQ) and the SF-36 in order to examine the CAT’s construct validity. A priori criterion for construct validity was that 75% of the correlations between the CAT dimensions and the subscales of the other questionnaires were as expected. Furthermore, comprehensive use of the item bank, measurement precision and score distribution were investigated.Results
The a priori criterion for construct validity was supported for two of the three CAT dimensions (severity and impact but not for variability). For severity and impact, 87% of the correlations with the subscales of the well-established questionnaires were as expected but for variability, 53% of the hypothesised relations were found. Eighty-nine percent of the items were selected between one and 137 times for CAT administrations. Measurement precision was excellent for the severity and impact dimensions, with more than 90% of the CAT administrations reaching a standard error below 0.32. The variability dimension showed good measurement precision with 90% of the CAT administrations reaching a standard error below 0.44. No floor- or ceiling-effects were found for the three dimensions.Conclusion
The CAT Fatigue RA showed good construct validity and excellent measurement precision on the dimensions severity and impact. The dimension variability had less ideal measurement characteristics, pointing to the need to recalibrate the CAT item bank with a two-dimensional model, solely consisting of severity and impact. 相似文献37.
Yongqing Liu Jan H. W. Bergervoet C. H. Ric De Vos Henk W. M. Hilhorst H. Lieke Kraak Cees M. Karssen Raoul J. Bino 《Planta》1994,194(3):368-373
The role of cis-abscisic acid (ABA) and gibberellins (GAs) in the induction of cell-cycle activities has been studied during imbibition and subsequent germination of tomato seeds. Using flow cytometry, nuclear replication activity was investigated in embryo root tips isolated from seeds of the ABA-deficient mutant sit w , the GA-deficient mutant gib-1, and the wild-type (MM) tomato (Lycopersicon esculentum Mill. cv. Moneymaker) upon imbibition in water, 10 μM GA4+7, 5 μM ABA or 5 μM ABA+10 μM GA4+7. The nuclei of fully matured dry MM, sit w and gib-1 seeds predominantly showed 2C DNA signals, indicating that the cell-cycle activity of most root-tip cells had been arrested at the G1 phase of nuclear division. However, ABA-deficient sit w seeds contained a significantly higher amount of G2 cells (4C DNA) compared with the other genotypes, suggesting that, during maturation, cell-cycle activity in sit w seeds is less efficiently arrested in G1. Upon imbibition in water, an induction of the 4C signal, indicating nuclear replication, was observed in the root tip cells of both MM and sit w embroys. The augmentation in the 4C signal occurred before visible germination. Gib-1 seeds did not show cell-cycle activity and did not germinate in water. Upon imbibition in GA4+7, both cell-cycle activity and subsequent germination were enhanced in MM and sit w seeds, and were induced in gib-1. In ABA, the germination of MM and sit w seeds was inhibited while nuclear replication of these seeds was not affected. It is concluded that GA influences germination by acting upon processes that precede cell-cycle activation, while ABA affects growth by acting upon processes that follow cell-cycle activation. 相似文献
38.
Steve Horvath Abu NM Nazmul-Hossain Rodney PE Pollard Frans GM Kroese Arjan Vissink Cees GM Kallenberg Fred KL Spijkervet Hendrika Bootsma Sara A Michie Sven U Gorr Ammon B Peck Chaochao Cai Hui Zhou David TW Wong 《Arthritis research & therapy》2012,14(6):1-13
Bone tissue has an exceptional quality to regenerate to native tissue in response to injury. However, the fracture repair process requires mechanical stability or a viable biological microenvironment or both to ensure successful healing to native tissue. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. Preclinical and clinical studies using biologic agents like recombinant bone morphogenetic proteins have demonstrated an efficacy similar or better than that of autologous bone graft in acute fracture healing. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications. 相似文献
39.
Chris J. van Koppen Marcel W. Hermanussen Kiek N. Verrijp Jaap F. Rodrigues de Miranda Arie J. Beld Jan-Willem J. Lammers Cees A. M. van Ginneken 《Life sciences》1987,40(26):2561-2570
Specific binding of [125I]-(−)-cyanopindolol to human tracheal smooth muscle membranes was saturable, stereo-selective and of high affinity (Kd=5.3±0.9 pmol/l and RT=78±7fmol/g tissue). The β1-selective antagonists atenolol and LK 203-030 inhibited specific [125I]-(−)-cyanopindolol binding according to a one binding site model with low affinity in nearly all subjects, pointing to a homogeneous β2-adrenoceptor population. In one subject using LK 203-030 a small β-adrenoceptor subpopulation could be demonstrated. The beta-mimetics isoprenaline, fenoterol, salbutamol and terbutaline recognized high and low affinity agonist binding sites. Isoprenaline's pKH- and pKL- values for the high and low affinity sites were 8.0±0.2 and 5.9±0.3 respectively. In functional experiments isoprenaline relaxed tracheal smooth muscle strips having intrinsic tone with a pD2-value of 6.63±0.19. 相似文献
40.
Janna A. van Diepen Rinke Stienstra Irene O. C. M. Vroegrijk Sjoerd A. A. van den Berg Daniela Salvatori Guido J. Hooiveld Sander Kersten Cees J. Tack Mihai G. Netea Johannes W.A. Smit Leo A. B. Joosten Louis M. Havekes Ko Willems van Dijk Patrick C. N. Rensen 《Journal of lipid research》2013,54(2):448-456
Caspase-1 is known to activate the proinflammatory cytokines IL-1β and IL-18. Additionally, it can cleave other substrates, including proteins involved in metabolism. Recently, we showed that caspase-1 deficiency in mice strongly reduces high-fat diet-induced weight gain, at least partly caused by an increased energy production. Increased feces secretion by caspase-1-deficient mice suggests that lipid malabsorption possibly further reduces adipose tissue mass. In this study we investigated whether caspase-1 plays a role in triglyceride-(TG)-rich lipoprotein metabolism using caspase-1-deficient and wild-type mice. Caspase-1 deficiency reduced the postprandial TG response to an oral lipid load, whereas TG-derived fatty acid (FA) uptake by peripheral tissues was not affected, demonstrated by unaltered kinetics of [3H]TG-labeled very low-density lipoprotein (VLDL)-like emulsion particles. An oral gavage of [3H]TG-containing olive oil revealed that caspase-1 deficiency reduced TG absorption and subsequent uptake of TG-derived FA in liver, muscle, and adipose tissue. Similarly, despite an elevated hepatic TG content, caspase-1 deficiency reduced hepatic VLDL-TG production. Intestinal and hepatic gene expression analysis revealed that caspase-1 deficiency did not affect FA oxidation or FA uptake but rather reduced intracellular FA transport, thereby limiting lipid availability for the assembly and secretion of TG-rich lipoproteins. The current study reveals a novel function for caspase-1, or caspase-1-cleaved substrates, in controlling intestinal TG absorption and hepatic TG secretion. 相似文献