Review of international standards for dosemeters

International standards for radiation protection dosemeters are published by the International Electrotechnical Commission and the International Organization for Standardization. Several standards exist side by side, although they treat the same measuring task, and specify different requirements, so that dosemeters of different quality result. In this paper, the quality of dosemeters is compared by calculating the uncertainty of dose measurements for dosemeters, which just basely fulfil the respective standard. The results are related to general yardsticks on uncertainty laid down by international organisations. Furthermore, technical differences are standards and addressed and a method to make them conform is presented.

Gemcitabine, oxaliplatin and weekly high-dose 5-FU as 24-h infusion in chemonaive patients with advanced or metastatic pancreatic adenocarcinoma: a multicenter phase II trial of the Arbeitsgemeinschaft Internistische Onkologie (AIO)

BACKGROUND

Combinations of gemcitabine-oxaliplatin, gemcitabine-5-fluorouracil (5-FU) and 5-FU-oxaliplatin have synergistic activity and nonoverlapping adverse effect profiles. This trial assessed efficacy and safety of the triple combination gemcitabine-oxaliplatin and infusional 5-FU in patients with locally advanced (n=11) or metastatic (n=32) pancreatic adenocarcinoma.

PATIENTS AND METHODS

A total of 43 eligible patients were treated with intravenous infusions of gemcitabine (900 mg/m2 over 30 min), followed by oxaliplatin (65 mg/m2 over 2 h) and 5-FU (1500 mg/m2 over 24 h) on days 1 and 8 of a 21-day cycle.

RESULTS

Among all 43 patients, the tumor response rate was 19% [95% confidence interval 7% to 30%]. Nine patients were nonassessable for response because they did not complete the first two cycles of chemotherapy due to rapid disease progression, early death or treatment refusal. One patient was lost to follow-up. Median time to progression and overall survival were 5.7 and 7.5 months. Principal grade III/IV toxic effects were leucopenia in 11 (2%), thrombocytopenia in 13 (2%), nausea in 13 (0%), anorexia 16 (7%) and sensory neuropathy in 18 (0%) of patients. Unexpected cardiotoxicity was observed in this trial.

CONCLUSION

Response rates and survival of the three-drug combination compare favorably with single-agent gemcitabine, but do not exceed results for doublets.

The neutron component of two high-energy photon reference fields

The 4.4 MeV photon reference field described in ISO 4037 is produced by the (12)C(p,p')(12)C (E(x) = 4.4389 MeV) reaction using a thick elemental carbon target and a proton beam with an energy of 5.7 MeV. The relative abundance of the isotope (13)C in elemental carbon is 1.10%. Therefore, the 4.4 MeV photon field is contaminated by neutrons produced by the (13)C(p,n) (13)N reaction (Q = -3.003 MeV). The ambient dose equivalent H*(10) produced by these neutrons is of the same order of magnitude as the ambient dose equivalent produced by the 4.4 MeV photons. For the calibration of dosemeters, especially those also sensitive to neutrons, the spectral fluence distribution of these neutrons has to be known in detail. On the other hand, a mixed photon/neutron field is very useful for the calibration of tissue-equivalent proportional counters (TEPC), if this field combines a high-linear energy transfer (LET) component produced by low-energy neutrons and a low-LET component resulting from photons with about the same ambient dose equivalent and energies up to 7 MeV. Such a mixed field was produced at the PTB accelerator facility using a thin CaF(2) + (nat)C target and a 5.7 MeV proton beam.

How to type test the coefficient of variation of an indication

Type tests are common methods to verify whether an instrument is suitable for a specific measuring task or not. In several countries, the type test is legally required and if failed the respective instrument cannot be used for legal measurements and, therefore, will not be bought by many customers. One important quantity is the coefficient of variation of the indication, which shall not exceed a given acceptance limit. In order to keep the amount of required measurements manageable, the coefficient of variation is estimated at one or a few test conditions from a limited number of measurements. The current test procedure requires that the measured coefficients of variation shall not exceed the respective acceptance limit at all test conditions. This paper demonstrates that the current test procedure has the unwanted tendency to reject instruments which should pass the test. Based on this realisation, the authors modified the test procedure to achieve proper results. The changes do not require further measurements, only the data evaluation has been optimised.

Gemcitabine, oxaliplatin and weekly high-dose 5-FU as a 24-hr-infusion in chemonaive patients with advanced or metastatic carcinoma of the gallbladder: Preliminary results of a multicenter phase II-study

4129

Background: Combinations of gemcitabine (GEM)/5-FU, GEM/oxaliplatin (LOHP) or 5-FU/LOHP work synergistically in pancreatic and/or colorectal malignancies, and have non-overlapping safety profiles. This phase II-study was designed to evaluate the efficacy and safety of the triple combination GEM/LOHP/5-FU in patients (pts) with advanced or metastatic carcinoma of the gallbladder. Methods: One-stage, multicentre phase II study. Eligibility criteria: chemonaive pts with histologically proven advanced, recurrent or metastatic gallbladder carcinoma (ECOG 0–1; expected survival >3 months; measurable disease; adequate renal, hepatic and bone marrow function). According to the results of our previous phase I-study (Proc ASCO 2003, # 1298), pts were treated with GEM 900mg/m2 as a 30-min infusion, followed by LOHP 65 mg/m2 (2-hr infusion) after a 30 min rest and 5-FU 1500 mg/m2 (24-hr-infusion) on d 1, 8, every 3 weeks. Planned sample size: 35 response evaluable patients. The primary endpoint was tumor response, secondary endpoints were toxicity, median survival, the one-year-survival rate, clinical benefit and quality of life. Results: At time of abstract submission, median follow-up of 35 enrolled pts is 9.8 months. Pt. characteristics: m/f: 11/24, median age 61 (range 42–81), ECOG 0/1: 24/11 (69/31%) pts, locally advanced/metastatic disease 1/32 (3/91%) pts. Analysis of tumor response is still pending. Grade III/IV (NCI-CTC) toxicities occurred in 36/3% of 191 cycles and were: leucopenia 3/1%, neutropenia 4/1%, thrombocytopenia 4/1%, anemia 2/0%, nausea 1/0%, sensory neuropathy 4/0%, asthenia 1/0%, elevated bilirubin 2/0%, AP 4/0%, or elevated SGOT/SGPT 1/0%, edema 1/0%, infection 1/0%, dyspnoe 1/1%. Median survival of all pts is 9.9 months (95% CI: 7.5–11.5), the one-year-survival-rate is 30 % (95% CI: 16–47). Conclusions: GEM/LOHP/5-FU combination therapy is tolerated well in patients with gallbladder cancer. The promising survival data has to be confirmed in a phase III study. (Supported by grants from Eli Lilly and Company, Indianapolis, IN, USA and Sanofi-Synthelabo, Paris, France).

[Table: see text]

Pharmacokinetics and pharmacodynamic action of budesonide in children with Crohn's disease

BACKGROUND

Budesonide is effective as initial therapy of mild to moderate Crohn's disease in adults. Superior tolerability to conventional corticosteroids might be attributed to extensive first-pass metabolism of budesonide by cytochrome P450 3A.

AIM

To evaluate biotransformation and pharmacodynamic action of budesonide in children.

METHODS

Drug disposition and effects on endogenous cortisol were evaluated in 12 children with Crohn's disease (5-15 years) after first intake of 3 mg budesonide (single dose), and again after 1 week of thrice daily dosing (steady-state). The parent drug and cytochrome P450 3A-dependent metabolites were analysed in blood and urine.

RESULTS

Pharmacokinetic parameters of budesonide following single-dose administration (e.g. AUC(0-infinity) 7.7+/-5.1 h ng/mL, C(max) 1.8+/-1.2 ng/mL) did not change upon multiple dosing. Overall systemic elimination of budesonide reflected by clearance and half-life was not different between children and adults. After 1 week of treatment reversible adrenal suppression was observed - most pronounced in children aged below 12 years.

CONCLUSIONS

Disposition of oral budesonide appears to be similar between children and adults, but the doctor has to be aware of an increased risk for adrenal suppression in paediatric patients.

Imported Falciparum malaria in Europe: sentinel surveillance data from the European network on surveillance of imported infectious diseases

Malaria continues to have a high morbidity rate associated among European travelers. Thorough recording of epidemiological and clinical aspects of imported malaria has been helpful in the detection of new outbreaks and areas of developing drug resistance. Sentinel surveillance of data collected prospectively since 1999 has begun within TropNetEurop, a European network focusing on imported infectious diseases. TropNetEurop appears to cover approximately 10% of all patients with malaria seen in Europe. Reports of 1659 immigrants and European patients with Plasmodium falciparum malaria were analyzed for epidemiological information and data on clinical features. Regional data were quite diverse, reflecting local patterns of immigration and international travel. By far, the most infections were imported from West Africa. Europeans had more clinical complications; consequently, all deaths occurred in this group. Compared with European standards, the mortality rate was low (0.6% in Europeans). Data from TropNetEurop member sites can contribute to our understanding of the epidemiological and clinical findings regarding imported falciparum malaria.

A TLD-based few-channel spectrometer for mixed photon, electron, and ion fields with high fluence rates

A few-channel spectrometer for mixed photon, electron and ion radiation fields has been developed. It consists of a front layer of an etched-track detector foil for detecting protons and ions, a stack of PMMA with thermoluminescent detectors at different depths for gaining spectral information about electrons, and a stack of metallic filters with increasing cut-off photon energies, interspersed with thermoluminescent detectors for gaining spectral information about photons. From the reading of the TL detectors the spectral fluence of the electrons (400 keV to 9 MeV) and photons (20 keV to 2 MeV) can be determined by an unfolding procedure. The spectrometer can be used in pulsed radiation fields with extremely high momentary values of the fluence rate. Design and calibration of the spectrometer are described.

Presynaptic Ca2+-activated K+ channels in glutamatergic hippocampal terminals and their role in spike repolarization and regulation of transmitter release

Large-conductance Ca(2+)-activated K(+) channels (BK, also called Maxi-K or Slo channels) are widespread in the vertebrate nervous system, but their functional roles in synaptic transmission in the mammalian brain are largely unknown. By combining electrophysiology and immunogold cytochemistry, we demonstrate the existence of functional BK channels in presynaptic terminals in the hippocampus and compare their functional roles in somata and terminals of CA3 pyramidal cells. Double-labeling immunogold analysis with BK channel and glutamate receptor antibodies indicated that BK channels are targeted to the presynaptic membrane facing the synaptic cleft in terminals of Schaffer collaterals in stratum radiatum. Whole-cell, intracellular, and field-potential recordings from CA1 pyramidal cells showed that the presynaptic BK channels are activated by calcium influx and can contribute to repolarization of the presynaptic action potential (AP) and negative feedback control of Ca(2+) influx and transmitter release. This was observed in the presence of 4-aminopyridine (4-AP, 40-100 microm), which broadened the presynaptic compound action potential. In contrast, the presynaptic BK channels did not contribute significantly to regulation of action potentials or transmitter release under basal experimental conditions, i.e., without 4-AP, even at high stimulation frequencies. This is unlike the situation in the parent cell bodies (CA3 pyramidal cells), where BK channels contribute strongly to action potential repolarization. These results indicate that the functional role of BK channels depends on their subcellular localization.

[Two rare complications of percutaneous endoscopic gastrostomy: obstruction of the pylorus and gastrocolic fistula occurring in one patient]

We report an 10 month old male infant, who developed an obstruction of the pylorus by dislocation of the retention disk 5 months after percutaneous endoscopic gastrostomy (PEG). This could be corrected under endoscopic control. Two years after PEG insertion diarrhoe occurred immediately after feeding caused by a gastrocolic fistula with dislocation of the retention disk in the colon transversum. An excision of the fistula and a resection of the colon segment were performed successfully.

CONCLUSION

In patients with PEG and unclear abdominal symptoms a tube dislocation has to be kept in mind at any time.

Balloon dilation is preferable to bougienage in children with esophageal atresia

BACKGROUND AND STUDY AIMS

Esophageal strictures are a common problem after surgical repair in children with esophageal atresia. The traditional procedure in these patients is dilation using bougie dilators, usually controlled fluoroscopically or endoscopically. Nowadays, an alternative technique is balloon-catheter dilation. The aim of this study was to report our experience with pneumatic balloon dilation and to compare this method with previously performed bougienage with regard to efficacy.

PATIENTS AND METHODS

Over 16 years, 34 patients who developed symptomatic strictures were encountered at our institution. In the first 9 years 12 patients underwent 178 bougienages (group C). In the last 7 years six patients who had undergone 202 previous bougienages (group B), and 16 patients who had undergone no bougienages (group A), underwent 52 dilations. The dilation was carried out under intravenous sedation using a combination of midazolam and etomidate. The balloon was placed in the stricture endoscopically and the procedure was performed under fluoroscopic and endoscopic control.

RESULTS

In all patients the dilation was effective and involved minimal trauma. The strictures required 1 to 7 procedures (median 2) over a maximum of 18 months (median 3 months) for a good treatment result. The complications observed were two perforations, one of them with pneumothorax (both treated conservatively), and two compressions of the trachea (interruption of the procedure, but efficient dilation was eventually achieved). The method was more effective than bougienage (1 to 60 bougienages were required per patient, median 9).

CONCLUSIONS

Compared with traditional bougienage, balloon dilation of esophageal strictures is less traumatic and more effective. Complications are rare and can be managed conservatively. In our opinion this procedure is the appropriate treatment for strictures, even in very small infants, after repair of esophageal atresia.

Mev X rays and photoneutrons from femtosecond laser-produced plasmas

We demonstrate a novel method to monitor the total angular distribution of the spectrum of hard x-ray emission from a plasma generated with femtosecond laser pulses with an intensity of 5 x 10(18) W/cm2 on a solid target. Measured and calculated angular distributions of x rays show a pronounced anisotropy for MeV photon energies. We complemented the spectral information by demonstrating a (gamma,n) nuclear reaction with a tabletop laser system.

Fission yeast retrotransposon Tf1 integration is targeted to 5' ends of open reading frames

Target site selection of transposable elements is usually not random but involves some specificity for a DNA sequence or a DNA binding host factor. We have investigated the target site selection of the long terminal repeat-containing retrotransposon Tf1 from the fission yeast Schizosaccharomyces pombe. By monitoring induced transposition events we found that Tf1 integration sites were distributed throughout the genome. Mapping these insertions revealed that Tf1 did not integrate into open reading frames, but occurred preferentially in longer intergenic regions with integration biased towards a region 100-420 bp upstream of the translation start site. Northern blot analysis showed that transcription of genes adjacent to Tf1 insertions was not significantly changed.

Balloon dilation of an esophageal stenosis in a patient with recessive dystrophic epidermolysis bullosa

We report a 13-year-old boy with recessive dystrophic epidermolysis bullosa who had dysphagia due to esophageal stenosis. A balloon dilation was successfully performed under flexible endoscopic and fluoroscopic control. The early and long-term follow-up was characterized by the disappearance of dysphagia, weight gain, and improvement of his skin lesions.

Pharmacokinetics of orally administered omeprazole in children. International Pediatric Omeprazole Pharmacokinetic Group

OBJECTIVES

The aim of this study was to examine the pharmacokinetics of orally administered omeprazole in children.

METHODS

Plasma concentrations of omeprazole were measured at steady state over a 6-h period after administration of the drug. Patients were a subset of those in a multicenter study to determine the dose, safety, efficacy, and tolerability of omeprazole in the treatment of erosive reflux esophagitis in children. Children were 1-16 yr of age, with erosive esophagitis and pathological acid reflux on 24 h-intraesophageal pH study. The "healing dose" of omeprazole was that at which subsequent intraesophageal pH study normalized. Children remained on this dose for 3 months, and during this period the pharmacokinetics were measured.

RESULTS

A total of 57 children were enrolled in the overall healing phase of the study. Pharmacokinetic study was optional for subjects and was performed in 25 of the 57 enrolled. The doses of omeprazole required were substantially higher doses per kilogram of body weight than in adults. Values of the pharmacokinetic parameters of omeprazole were generally within the ranges previously reported in adults. However, the plasma levels, area under the plasma concentration versus time curve (AUC), plasma half-life (t(1/2)), and maximal plasma concentration (Cmax), were lower in the younger age group, when the AUC and Cmax were normalized to a dose of 1 mg/kg. Furthermore, within the group as a whole, these values showed a gradation from lowest in the children 1-6 yr of age to higher in the older age groups.

CONCLUSIONS

The pharmacokinetics of omeprazole in children showed a trend toward higher metabolic capacity with decreasing age, being highest at 1-6 yr of age. This may explain the need for higher doses of omeprazole on a per kilogram basis, not only in children overall compared with adults but, in many cases, particularly in younger children.