Intra- and interlaboratory calibration of the DR CALUX bioassay for the analysis of dioxins and dioxin-like chemicals in sediments

In the Fourth National Policy Document on Water Management in The Netherlands, it is defined that in 2003, in addition to the assessment of chemical substances, special guidelines for the assessment of dredged material should be recorded. The assessment of dredged material is based on integrated chemical and biological effect measurements. Among others, the DR CALUX (dioxin responsive-chemically activated luciferase expression) bioassay has tentatively been recommended for inclusion in the dredged material assessment. To ensure the reliability of this bioassay, an intra- and interlaboratory validation study, or ring test, was performed, organized by the Dutch National Institute for Coastal and Marine Management (RIKZ) in cooperation with BioDetection Systems BV (BDS). The intralaboratory repeatability and reproducibility and the limit of detection (LOD) and quantification (LOQ) of the DR CALUX bioassay were determined by analyzing sediment extracts and dimethyl sulfoxide (DMSO) blanks. The highest observed repeatability was found to be 24.1%, whereas the highest observed reproducibility was calculated to be 19.9%. Based on the obtained results, the LOD and LOQ to be applied for the bioassay are 0.3 and 1.0 pM, respectively. The interlaboratory calibration study was divided into three phases, starting with analyzing pure chemicals. During the second phase, sediment extracts were analyzed, whereas in the third phase, whole sediments had to be extracted, cleaned, and analyzed. The average interlaboratory repeatability increased from 14.6% for the analysis of pure compound to 26.1% for the analysis of whole matrix. A similar increase in reproducibility with increasing complexity of handlings was observed with the interlaboratory reproducibility of 6.5% for pure compound and 27.9% for whole matrix. The results of this study are intended as a starting point for implementing the integrated chemical-biological assessment strategy and for systematic monitoring of dredged materials and related materials in the coming years.     

Developmental Exposure to 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107): Long-Term Effects on Brain Development, Behavior, and Brain Stem Auditory Evoked Potentials in Rats

In the present study the developmental neurotoxic effects ofthe PCB metabolite 4-OH-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107)were compared with effects caused by a mixture of parent polychlorinatedbiphenyl (PCB) congeners (Aroclor 1254). Pregnant female Wistarrats were exposed to 0.5 or 5 mg 4-OH-CB107, or 25 mg Aroclor1254 per kg body weight from gestation days 10 to 16. Plasmathyroid hormone levels were significantly decreased in the offspringof all treatment groups at postnatal day 4 (PND 4). Behavioralexperiments using an open field paradigm revealed an impairedhabituation in male offspring of all treatment groups at PND130. Passive avoidance experiments indicated significant influenceson the time course of step-down latencies across trials in exposedmale rats. Catalepsy induced by haloperidol showed increasesin latencies to movement onset in female offspring exposed to0.5 mg 4-OH-CB107 compared to Aroclor 1254 treated offspringat PND 168–175. Male offspring exposed to 4-OH-CB107 orAroclor 1254 showed decreases in latencies compared to controlanimals. Brain stem auditory evoked potentials (BAEPs) measuredat PND 300–310 showed significant increases in auditorythresholds in the low frequency range between Aroclor 1254 and4-OH-CB107 (5 mg/kg bw) treated animals. Measurements of neurotransmitterlevels revealed effects of Aroclor 154 exposure on both thedopaminergic and the serotonergic systems, whereas 4-OH-CB107exposure affected dopaminergic and noradrenergic systems, withslight but not significant effects on the serotonergic system.These results indicate that 4-OH-CB107 is able to induce long-termeffects on behavior and neurodevelopment. The observed effectsfor 4-OH-CB107 are similar to, but in some aspects differentfrom, the effects observed after Aroclor 1254 exposure.     

Perinatal and maternal complications related to postterm delivery: a national register-based study, 1978-1993

OBJECTIVE: This study was undertaken to estimate the risk of fetal and maternal complications associated with postterm delivery in Denmark. STUDY DESIGN: A cross-sectional study that used records from the Danish Medical Birth Registry from 1978 to 1993 was performed. All women with registered prolonged pregnancy (n = 78022) and a 5% random sample of all women who gave birth (n = 47021) were linked to the Danish National Discharge Register. We established a postterm group of 77956 singleton deliveries and a term group of 34140 singleton spontaneous deliveries. Logistic regression models were used to analyze data. RESULTS: The risk of perinatal and obstetric complications was high in postterm delivery compared with term delivery (adjusted odds ratios between 1.2 and 3.1). The risk of perinatal death was 1.33 (1.05-1.68). CONCLUSION: Postterm delivery was associated with significantly increased risks of perinatal and maternal complications in Denmark in the period from 1978 to 1993.     

Prolonged nicotine patch use in quitters with past abstinence-induced depressed mood

To test the efficacy of sustained nicotine patch use among at-risk smokers, 55 smokers with a history of abstinence-induced depressed mood were randomly assigned to either Nicotine Maintenance or Standard Treatment following preliminary high-dose patch treatment. The Nicotine Maintenance group received 21 mg transdermal nicotine for 8 additional weeks; the Standard Treatment group followed a tapered dosing regimen. Significant differences favoring the Nicotine Maintenance group were found in self-reported craving but not withdrawal. No difference was observed in continuous abstinence or in relapse rates. When dropouts who did not relapse during patch use were classified as successful, however, the Nicotine Maintenance group had significantly lower relapse rates. Rate of lapse in the Nicotine Maintenance group during post-trial tapering did not differ significantly from that in the Standard Treatment group during tapering in the trial, suggesting that the benefits of sustained dosing may persist only as long as dosing continues.     

Should I stay or should I go? Waiting lists and cross-border care in the Netherlands

The recent ruling of the European Court of Justice in the case Smits-Peerbooms explicitly mentions undue delay as a legitimisation for cross-border care within the EU. In the Netherlands, waiting times are well above the norm set by several health care parties as well as maximally acceptable waiting times elicited in patients. This might indicate that Dutch patients are often entitled to care in other Member States, in the sense that insurers cannot withhold reimbursement of cross-border care in the present situation. However, experiments clearly demonstrate that few Dutch patients are willing to travel abroad. Patients seem to prefer longer waiting in the Netherlands over shorter waiting by going abroad, even those living in border regions. In addition, mobility of patients within the Netherlands is very modest. Given this inertia in patient mobility, in the short run, cross-border care will probably remain an insignificant phenomenon in terms of quantities of patients travelling abroad and therefore the impact of the Smits-Peerbooms rulings is limited.     

Adaptive intrapatient dose escalation of cisplatin in combination with low-dose vp16 in patients with nonsmall cell lung cancer

The objective of this phase II and pharmacologic study was to explore the feasibility, toxicity and activity of adaptive intrapatient dose escalation of cisplatin in a dose-intensive weekly schedule using predefined levels of exposure, with the ultimate aim to improve the antitumour activity of the therapy in patients with nonsmall cell lung cancer (NSCLC). Platinum DNA-adduct levels in peripheral white blood cells during treatment were used as the primary parameter for adaptive dosing. If DNA-adduct levels were not available, the area under the concentration-time curve (AUC) of unbound platinum in plasma was used for dose adaptation. Target levels for DNA-adducts and AUC have been defined in a previously performed pharmacologic study. The feasibility of adaptive dosing was tested in 76 patients with stage IIIB and IV NSCLC, who were planned to receive 6 weekly courses of cisplatin at a starting dose of 70 mg m(-2), together with daily low oral dose of 50 mg VP16. In total, 37 patients (49%) who were given more than one course received a dose increase varying from 10 to 55%. The majority of patients reached the defined target levels by a dose increase during course two. Relevant grade 2 neurotoxicity was observed in eight (10%) patients and reversible ototoxicity grade 2 in 14 (18%) patients. The strategy of adaptive intrapatient dose adjustment of cisplatin is practically feasible in a research setting even when results for dose adaptation have to be reported within a short time-period of 1 week. The toxicity appeared to be manageable in this cohort of patients. In some patients, exposure after the standard dose was substantially lower than the defined target level and significant dose escalations of more than 50% had to be applied. The response rate (RR) was relatively high: overall 40% (29 out of 72 patients) partial remission (PR), in patients with stage IIIB the RR was 60% (15 out of 25 patients) and with stage IV 30% (14 out of 47 patients). Randomised studies are needed to determine whether the adaptive dosing strategy results in better efficacy than standard dosing.     

The missing link: on the line between C and E

In this paper it is argued that the separation of elements associated with the time spent by the patient is not conducted in a consistent way. This is the case for income (for which there at least has been some attention) and for other time elements like lost unpaid work, leisure and role-functioning. The use of general rather than specific preferences in health state assessments makes the separation of time-elements into costs and effects difficult. While costs are calculated specifically for the patient group under study, effects are normally derived from preferences in the general public. The characteristics of these two groups in terms of (the opportunity of) spending time on activities need not coincide. The use of specific time-group valuations of health states may be a good alternative to using general health state valuations.     

Probenecid-associated alterations in valproate glucuronide hepatobiliary disposition: mechanistic assessment using mathematical modeling

The complexity of processes associated with the hepatobiliary disposition of xenobiotics may require a multiexperimental approach, including pharmacokinetic modeling, to assess mechanisms of drug interactions. The objective of this study was to examine the disposition of valproate glucuronide (VG) in the rat isolated perfused liver (IPL), and to determine the mechanisms of interaction with probenecid (PRB). Livers were isolated and perfused with standard techniques, and valproate (VPA) (20 mg) was administered in the absence and presence of PRB (approximately 75 microg/ml). Concentrations of VPA and VG in perfusate and bile were determined at timed intervals. In the absence of PRB, total recovery of VPA and VG in perfusate and bile was approximately 80%; PRB significantly increased this recovery to approximately 100%, suggesting a decrease in oxidative VPA metabolism. Similarly, pharmacokinetic modeling of the IPL data indicated that PRB competitively inhibited formation of oxidative VPA metabolites. PRB also significantly inhibited formation, biliary excretion, and sinusoidal egress of VG. These observations suggest a competitive interaction between PRB and VG for transport across the canalicular and sinusoidal membranes. Despite PRB-associated impairment of VG formation, mathematical modeling of the data revealed that hepatocyte VG concentrations were increased by PRB, presumably due to simultaneous inhibition of VG biliary excretion and sinusoidal egress by PRB. These results demonstrate the utility of pharmacokinetic modeling in elucidating the mechanisms of alteration in the hepatobiliary disposition of xenobiotics.     

LPS-induced expression of a novel chemokine receptor (L-CCR) in mouse glial cells in vitro and in vivo

There is increasing evidence that chemokines, specialized regulators of the peripheral immune system, are also involved in the physiology and pathology of the CNS. It is known that glial cells (astrocytes and microglia) express various chemokine receptors like CCR1, -3, -5, and CXCR4. We have investigated the possible expression of the known CC chemokine receptors (CCR1-8 and D6) in murine glial cells. In addition, we examined possible glial expression of the orphan CC chemokine receptor L-CCR that has been identified previously in murine macrophages. We report here expression of L-CCR mRNA in murine astrocytes and microglia. Furthermore, L-CCR mRNA expression was strongly induced after application of bacterial lipopolysaccharide (LPS), both in vitro and in vivo. Functional studies and binding experiments using biotinylated monocyte chemoattractant protein (MCP)-1 (CCL2) indicate that CCL2 could be a candidate chemokine ligand for glial L-CCR. Based on the data presented, it is suggested that L-CCR is a functional glial chemokine receptor that is important in neuroimmunology.