[Can dental students and dental care providers in the Netherlands effectively and safely prescribe drugs?] / Serie: Onderwijs en de tandarts anno 2025. Kunnen tandheelkunde­studenten en mondzorgverleners in Nederland effectief en veilig geneesmiddelen voorschrijven?

Dentists and dental specialists are qualified to prescribe drugs. In this study, we assessed and compared the pharmacotherapeutic knowledge and skills of final year dental students, dentists and dental specialists in the Netherlands. In 2017, a random sample of these three groups was invited to complete an assessment. The knowledge assessment comprised 40 multiple choice questions covering often prescribed drugs. The skills assessment comprised three patient cases for which participants had to write a treatment plan. For the knowledge assessment, the response rates were 26 (20%) dental students, 28 (8%) dentists and 19 (19%) dental specialists, and for the skills assessment the response rates were 14 (11%) dental students, eight (2%) dentists, and eight (8%) dental specialists. On average, all three groups had inadequate knowledge scores (smaller 80%) and only a small proportion (smaller 30%) of their treatment plans was assessed as correct. These results suggest that dental students, dentists and dental specialists lack prescribing competence, which could be caused by poor pharmacotherapy education during under- and postgraduate dental training.

Accuracy of electrical field measurement using the flexible Schottky diode sheet at 433 MHz.

In this study, the accuracy of Schottky diode sensors mounted as a two-dimensional array on a flexible 125 micro m thick polyester foil has been studied. The diodes are placed at a distance of 2.5 x 2.5 cm, resulting in a measuring area of 20 x 20 cm. The diodes are placed across the gap between both arms (3 x 5 mm) of a dipole, total length 12 mm. High resistance (1 M Omega/m) carbon transmission lines printed on the sheet are used to connect each electrical (E) field sensor to the read-out electronics and a data-acquisition system. It is demonstrated that the flexible Schottky diode sheet can quantitatively measure E-field distributions at 433 MHz with an overall accuracy of approximately 6% (1 SD). The largest contribution to the inaccuracy is related to the phantom heterogeneity. The absolute sensitivity of this electrical field sensor is 0.71 V/m per V/m of the applied external electromagnetic field. The DC-voltage signal of the diodes shows a more or less square root relation to the RF-power applied to the applicator over a 15-fold range. An important feature of the system is that it provides the ability to perform on-line monitoring of the E-field, i.e. the SAR distribution of 433 MHz applicators. Further, it enables the introduction of fast and easy quality control protocols for superficial hyperthermia applicators.

Stability and accuracy of power and phase measurements of a VVM system designed for online quality control of the BSD-2000 (-3D) DHT system.

Accurate control of power and phase is essential for the quality assurance of hyperthermia treatments. Hereto, an external measurement device was inserted, built around a Vector Voltmeter (VVM), in order to assess online the performance of the steering capability of the BSD-2000 and later the BSD-2000-3D system. This paper only concerns the power and phase calibration of the signal in the path between the power and phase detection probes of the BSD-system and power and phase measurement point of the VVM. The calibration is performed in the frequency range of 60-120 MHz using a network analyser with a frequency range of 0.01-500 MHz. More importantly, by repeating the calibration periodically over the last 3 years, the stability and accuracy of the power and phase measurements were determined using the VVM system. The results of the power calibration show that the VVM system, concerning its power and phase measurement, is stable in time. The variation of the power measured with the VVM system is less than 0.22 dB (5.2%) for the latest configuration of the BSD-2000-3D system. The variation of the VVM-based phase measurements of the latter configurations is 1.1 degrees or less. From the results of the power and phase measurements in the BSD 2000 system reported in previous studies using other measurement systems, it follows that the uncertainties of the power and phase measurements with the currently proposed VVM system are small enough to assess accurately the performance of the BSD system concerning its steering capability.

Characterization of the SAR-distribution of the Sigma-60 applicator for regional hyperthermia using a Schottky diode sheet.

INTRODUCTION: Characterization of the performance of an hyperthermia applicator by phantom experiments is an essential aspect of quality assurance in hyperthermia. The objective of this study was to quantitatively characterize the energy distribution of the Sigma-60 applicator of the BSD2000 phased array system operated within the normal frequency range of 70-120 MHz. Additionally, the accuracy of the flexible Schottky diode sheet to measure E-field distributions was assessed. MATERIAL AND METHODS: The flexible Schottky diode sheet (SDS) consists of 64 diodes mounted on a flexible 125 microm thick polyester foil. The diodes are connected through high resistive wires to the electronic readout system. With the SDS E-field distributions were measured with a resolution of 2.5 x 2.5 cm in a cylindrical phantom, diameter of 26 cm and filled with saline water (2 g/l). The phantom was positioned symmetrically in the Sigma-60 applicator. RF-power was applied to the 4-channel applicator with increasing steps from 25W to a total output of 400 W. RESULTS: The complete system to measure the E-field distribution worked fine and reliably within the Sigma-60 applicator. The E-field distributions measured showed that the longitudinal length of the E-field distribution is more or less constant, e.g. 21-19 cm, over the frequency range of 70-120 MHz, respectively. As expected, the radial E-field distributions show a better focusing towards the centre of the phantom for higher frequencies, e.g. from 15.3-8.7 cm diameter for 70-120 MHz, respectively. The focusing target could be moved accurately from the left to the right side of the phantom. Further it was found that the sensitivity variation of nine diodes located at the centre of the phantom was very small, e.g. < 3% over the whole frequency range. CONCLUSION: The SAR distributions of the Sigma-60 applicator are in good agreement with theoretically expected values. The flexible Schottky diode sheet proves to be an excellent tool to make accurate, quantitative measurements of E-field distributions at low (25 W) and medium (400 W) power levels. An important feature of the SDS is that it enables one to significantly improve quantitative quality assurance procedures and to start quantitative comparisons of the performance of the different deep hyperthermia systems used by the various hyperthermia groups.

Theoretical comparison of the SAR distributions from arrays of modified current sheet applicators with that of lucite cone applicators using Gaussian beam modelling.

The technical comparison of Current Sheet Applicator (CSA) and Lucite Cone Applicator (LCA) arrays covering an area of approximately 20 x 20 cm2 is investigated based on Gaussian beam (GB) predicted SAR distributions. The comparison is made in muscle equivalent tissue at 1 cm depth (maximum SAR normalized to 100%) and over a volume of 3 cm depth under the aperture of the antennae. The planar SAR distribution is tested on field sizes (FSx: area covering x% SAR), penetration depth (PD) and homogeneity coefficient (HC = FS75/FS25). From the SAR volume, a SAR-Volume histogram (volume enclosing y% SAR/total volume) is calculated as well as the volumetric HC. First, the prototype CSA (aperture 58 x 67 mm2, FS50 = 21 cm2) is technically modified to assure clinical safety and load independence. The modified CSA, the D-CSA, has an aperture of 66 x 75 mm2 with an FS50 = 28 cm2 and a PD of 10 mm, the LCA (aperture 105 x 105 mm2) has an FS50 = 76 cm2 and PD = 12 mm. The HC equals 0.21 (D-CSA), respectively 0.22 (LCA). Secondly, a 3 x 3 D-CSA array is compared with a 2 x 2 LCA array. The FS50s equals 72% (D-CSA), respectively 75% (LCA). The SAR-volume histograms, planar and volumetric HC show no significant difference; however, the planar HCs for D-CSA and LCA increase from 0.2-0.3, indicating that incoherently powered arrays from these antennae build SAR distributions constructively.

Low temperature sensing in tulip (Tulipa gesneriana L.) is mediated through an increased response to auxin.

Tulip (Tulipa gesneriana L.) is a bulbous plant species that requires a period of low temperature for proper growth and flowering. The mechanism of sensing the low temperature period is unknown. The study presented in this paper shows that the essential developmental change in tulip bulbs during cold treatment is an increase in sensitivity to the phytohormone auxin. This is demonstrated using a model system consisting of isolated internodes grown on tissue culture medium containing different combinations of the phytohormones auxin and gibberellin. Using mathematical modelling, equations taken from the field of enzyme kinetics were fitted through the data. By doing so it became apparent that longer periods of low temperature resulted in an increased maximum response at a lower auxin concentration. Besides the cold treatment, gibberellin also enhances the response to auxin in the internodes in this in vitro system. A working model describing the relationship between the cold requirement, gibberellin action and auxin sensitivity is put forward. Possible analogies with other cold-requiring processes such as vernalization and stratification, and the interaction of auxin and gibberellin in the stalk elongation process in other plant species are discussed.

Economic evaluation of traffic safety measures for transport companies.

This paper addresses the economic feasibility of measures to reduce the material damage of transport companies. Results are presented of a series of interviews among transport companies as well as from a postal questionnaire survey. Next, calculations are presented for three types of companies: a small family company, a large family company and a large formalised company. From the viewpoint of costs and benefits, damage prevention measures appear to be particularly interesting to larger companies. Small companies, being the largest group, tend to have an informal culture in which measures are less effective. Especially those measures for which no large investments are needed, which influence the behaviour of drivers and need not to be contracted out, are perceived as attractive by the transport companies.

Comparison of the clinical effectiveness of the 433 MHz Lucite cone applicator with that of a conventional waveguide applicator in applications of superficial hyperthermia.

PURPOSE: This report presents the final stage of our program to improve the quality of our superficial hyperthermia treatments. We have already demonstrated that the Lucite cone applicator (LCA), our technically improved water-filled, wave-guide applicator (WGA), is superior to the conventional WGA. The main objective of the present study was to investigate whether the technical improvements of a WGA were reflected in an improved clinical performance, e.g., a better temperature distribution. METHODS AND MATERIALS: Power and temperature analyses were performed retrospectively on 128 treatments of superficially located tumors (less than 4 cm depth). Twenty-three patients were treated alternately with a WGA setup and a LCA setup. RESULTS: The average power level per antenna in an array was 48 W and 62 W for the WGA and LCA respectively. The average invasively measured temperatures increased by 0.27 degrees C when the LCAs were used. The temperature difference between the center and the periphery of an antenna, averaged over the complete array of antennae, was 0.43 degrees C using WGAs and -0.05 degrees C using LCAs indicating a more uniform heating. The T90 of the invasively measured temperatures remained unchanged (WGA: 39.4 degrees C versus LCA: 39.5 degrees C). CONCLUSION: The LCA is now our standard applicator for superficial hyperthermia treatments as it is technically and clinically proven to be superior to the WGA.

Reirradiation combined with hyperthermia in recurrent breast cancer results in a worthwhile local palliation.

Both experimental and clinical research have shown that hyperthermia (HT) gives valuable additional effects when applied in combination with radiotherapy (RT). The purpose of this study was evaluation of results in patients with recurrent breast cancer, treated at the Daniel den Hoed Cancer Center (DHCC) with reirradiation (re-RT; eight fractions of 4 Gy twice weekly) combined with HT. All 134 patients for whom such treatment was planned were included in the analysis. The complete response rate in 119 patients with macroscopic tumour was 71%. Including the 15 patients with microscopic disease, the local control rate was 73%. The median duration of local control was 32 months, and toxicity was acceptable. The complete response (CR) rate was higher, and the toxicity was less with the later developed 433-MHz HT technique compared with the 2450-MHz technique used initially. With this relatively well-tolerated treatment, palliation by local tumour control of a worthwhile duration is achieved in the majority of patients. The technique used for hyperthermia appeared to influence the achieved results. The value of HT in addition to this re-RT schedule has been confirmed by a prospective randomized trial in a similar patient group. In The Netherlands, this combined treatment is offered as standard to patients with breast cancer recurring in previously irradiated areas.

Quantitative evaluation of 2 x 2 arrays of Lucite cone applicators in flat layered phantoms using Gaussian-beam-predicted and thermographically measured SAR distributions.

SAR distributions from four different E-field-orientated 2 x 2 arrays of incoherently driven Lucite cone applicators (LCAs) were investigated. The LCAs operated at 433 MHz with an aperture of 10.5 cm x 10.5 cm each. Two techniques were used to obtain SAR distributions in flat layered phantoms: Gaussian beam (GB) predictions and thermographical (TG) imaging. The GB predictions showed that the effective field size of the different array configurations varied by up to 3%. The TG-measured SAR distribution showed significant deviations from the GB-predicted SAR distributions (maximum 34.6%). The difference between GB-predicted and TG-measured SAR levels (averaged per 10% GB-predicted SAR intervals) equalled less than 11.3% for the parallel E-field orientated array and respectively 15.1% for the clockwise-orientated array. When antennae in the clockwise-orientated array were more widely spread (array aperture 23 cm x 23 cm) in order to diminish their mutual interactions, these differences decreased to 12.4%. However, the overall difference within the 50% SAR or higher range decreased from 14% to 9%. The results lead us to conclude that LCAs can be used clinically and their antenna interactions are not considered to be a problem under clinical conditions.

Effectiveness of the Gaussian beam model in predicting SAR distributions from the lucite cone applicator.

The Gaussian beam model (GBM) has been shown to be a successful tool in the development of the current sheet applicator. As a result, the effectiveness of the GBM is investigated in single and dual array applications of the lucite cone applicator (LCA). The LCA is a modified water-filled waveguide applicator with an improved effective field size (EFS > 64 cm2, aperture 10 cm x 10 cm). The GB-source parameters were calculated from the emanating E-field of a single LCA. The SAR distribution from a single LCA was measured by E-field scanning and thermographic (TG) imaging, and compared with the GB-predicted SAR distribution. Deviations in the principal planes were found to be less than 5%. TG-measured and GB-predicted SAR distributions from three different dual LCA configurations were compared and evaluated. When water was used as intermedium between LCAs and phantom, a maximum SAR difference of 27% was calculated. In the absence of water as intermedium, this difference increased to 44%. These large deviations were only found in areas where the measured SAR distribution was disturbed due to antenna interactions. The average SAR differences with and without water as intermedium were 7% respectively 11%, indicating that the GBM can provide good qualitative information about the SAR distribution of dual LCA-arrays.

Practical limitations of interstitial thermometry during deep hyperthermia.

PURPOSE: Intratumor thermometry during hyperthermia treatment is considered important for several reasons. The morbidity that we experienced from interstitially placed catheters in deep-seated tumors gave reason to weigh the advantages and disadvantages against each other. METHODS AND MATERIALS: The available thermometry in 215 patients treated with hyperthermia for deep-seated tumors was analyzed with the aim to evaluate practically feasible intratumor measurements. The influence of intratumor measurements on the treatment procedure was assessed. RESULTS: Total 120 catheters were placed interstitially in 78 patients. Over the years, the percentage of patients with interstitial thermometry decreased considerably. Forty-nine catheters could remain in place during the whole hyperthermia treatment series. The remaining catheters had to be removed for more or less severe complications, including one fatal event. In fact, the interstitial catheters caused the most severe treatment-related morbidity. During 188 of the total 859 treatments, at least one interstitial catheter was available for thermometry. Per treatment with catheter(s) in situ, the average number of intratumor measurement sites was 6.9. The value of interstitial thermometry for power steering during treatment, to both optimize intratumor temperature distribution and prevent toxicity, appeared limited. The mean volume of the tumors with interstitial thermometry was 314 cm3, SD 325. In relation to the large tumor volumes, the thermal dose parameters calculated from the available data is considered to be of limited value. CONCLUSION: In view of the possible severe complications and the limited clinical value of the information achieved by interstitially placed thermometry catheters, interstitial thermometry was not found to routinely benefit the individual patient.

A 433 MHz Lucite cone waveguide applicator for superficial hyperthermia.

The effective field size (EFS, SAR > or = 50% of the maximum SAR at 1 cm depth) of a conventional 433 MHz water filled waveguide applicator (32 cm2, aperture area 100 cm2) has been increased by: (1) replacement of the two diverging brass side walls which are parallel to the direction of the electric field by Lucite walls; and (2) Placement of a heterogeneous permittivity in the centre of the aperture. SAR distributions were measured at several depths in layered fat-muscle phantoms. With Lucite side walls the SAR distribution becomes wider in the H-plane of the aperture, resulting in a circular SAR distribution. In this situation the EFS is 67 cm2. Additional insertion of a PVC cone with a top angle of 15 degrees at the centre of the aperture increases the EFS to 91 +/- 6 cm2 for a waterbolus of 18 x 18 x 1 cm3. The experiments also demonstrated that the resulting EFS is affected by the waterbolus size and shape. Calorimetric measurements showed that the efficiency of the improved applicator is comparable to the efficiency of the conventional water filled waveguide applicator, 50 and 56% respectively. The modifications reported provide a simple and inexpensive means to increase the EFS and can be easily implemented in water filled waveguide applicators.

Protein extration from an aqueous phase into a reversed micellar phase: Effect of water content and reversed micellar composition.

In the system composed of the cationic surfactant TOMAC (10 mM), the nonionic (co)surfactant Rewopal HV5 (2 mM), and octanol (0.1% v/v) in isooctane, reversed micelles are formed upon contact with an aqueous phase containing 50 mM ethylene diamine. alpha-Amylase can be transferred from the aqueous phase into reversed micelles in the pH range 9.5 to 10.5 and re-extracted into a second aqueous phase of different composition. The size of the reversed micelles (as reflected in the water content of the organic phase) can be varied by changes in percentage of octanol, type of counterion in the aqueous phase, or in the number of ethoxylate head groups of the nonionic surfactant. An increase in size results in transfer at lower pH values. Experiments in which the charge density in the reversed micellar interface was changed by incorporation of charged derivatives of the nonionic surfactant, without influencing the water content, revealed that an increased charge density facilitated transfer, resulting in a broader transfer profile. Replacement of TOMAC by other quaternary ammonium surfactants differing in number and length of tails revealed that, of the 14 surfactants tested, only 2 gave appreciable amounts of transfer. The amount of transfer is related to the dynamics of phase separation of the surfactants: those giving a poor phase separation inactivate the enzyme. This inactivation is caused by electrostatic interactions between the charged surfactant head groups and charged groups on the enzyme. Electrostatic interactions are the first step of transfer, and can result in either incorporation in a reversed micelle, or, if reversed micelle formation is slow, in enzyme inactivation. (c) 1995 John Wiley & Sons, Inc.

Reductive and oxidative half-reactions of glutathione reductase from Escherichia coli.

Glutathione reductase catalyzes the reduction of glutathione disulfide by NADPH and has a redox active disulfide and an FAD cofactor in each monomer. In the reductive half-reaction, FAD is reduced by NADPH and electrons pass from the reduced flavin to the redox active disulfide. The oxidative half-reaction is dithiol-disulfide interchange between the enzyme dithiol and glutathione disulfide. We have investigated the reductive and oxidative half-reactions using wild-type glutathione reductase from Escherichia coli and in an altered form of the enzyme in which the active site acid-base catalyst, His439, has been changed to an alanine residue (H439A). H439A has 0.3% activity in the NADPH/GSSG assay. The replacement affects both the oxidative half-reaction, as expected, and the reductive half-reaction--specifically, the passage of electrons from reduced flavin to the disulfide. Reduction of H439A by NADPH allows direct observation of flavin reduction. The NADPH-FAD charge transfer complex is formed in the dead time. Reduction of FAD, at a limiting rate of 250 s-1, is observed as a decrease at 460 nm and an increase at 670 nm (FADH(-)-NADP+ charge transfer). Subsequent passage of electrons from FADH- to the disulfide (increase at 460 nm and a decrease at 670 nm) is very slow (6-7 s-1) and concentration independent in H439A. The monophasic oxidative half-reaction is very slow, as expected for reduced H439A.(ABSTRACT TRUNCATED AT 250 WORDS)

Value functions for environmental pollutants: A technique for enhancing the assessment of expert judgements.

This paper presents a new procedure to assess value functions for environmental pollutants. It has been particularly designed for eliciting expert-based value functions for pollutant substances. The main features of the model are the possibility to integrate direct and indirect assessment techniques, the possibility to make explicit assessment uncertainties and to avoid forcing quantitative judgements. The main aim of the procedure is to improve the reliability of the assessment but also to make the expert's task easier by using qualitative judgements more frequently. The procedure has been developed especially for soil pollutants, for which an application is described.

Some practical notes on documentation of superficial hyperthermia treatment.

A detailed and accurate documentation of the treatment setup of each individual hyperthermia session is extremely important for retrospective data analysis as well as treatment quality control. In this paper the relatively simple and cheap documentation system developed by the Hyperthermia Department of the Dr Daniel den Hoed Cancer Center, is presented.

RFLP markers linked to the root knot nematode resistance gene Mi in tomato.

The Mi gene originating from the wild tomato species Lycopersicon peruvianum confers resistance to all major root knot nematodes (Meloidogyne spp.). This single dominant gene is located on chromosome 6 and is very closely linked to the acid phosphatase-1 (Aps-1) locus. Resistance to nematodes has been introgressed into various cultivars of the cultivated tomato (L. esculentum), in many cultivars along with the linked L. peruvianum Aps-1 (1) allele. By using a pair of nearly isogenic lines differing in a small chromosomal region containing the Mi and Aps-1 loci, we have identified two RFLP markers, GP79 and H6A2c2, which are located in the introgressed L. peruvianum region. Analysis of a test panel of 51 L. esculentum genotypes of various origins indicated that GP79 is very tightly linked to the Mi gene and allows both homozygous and heterozygous nematode-resistant genotypes to be distinguished from susceptible genotypes, irrespective of their Aps-1 alleles. Marker H6A2c2 is linked to the Aps-1 locus and is capable of discriminating between the L. peruvianum Aps-1 (1) allele and the L. esculentum Aps-1 (3) and Aps-1 (+) alleles. In combination, these RFLP markers may provide a powerful tool in breeding tomatoes for nematode resistance.

Intraregional income distribution and poverty: some investigations for the Netherlands, 1960-81.

"This paper is addressed to intraregional income inequalities in the Netherlands. Various concepts are used to measure the degree of regional poverty. In addition, dissimilarity between intraregional income distributions is studied. At the provincial level, relatively small and decreasing dissimilarities are observed. However, at lower spatial levels (especially within metropolitan areas) much larger dissimilarities in mean income and income distribution occur. In the Netherlands, urban poverty has become a more intense and widespread phenomenon than rural poverty."

Rural mobility in Java: the village economy and the rest of the world.

PIP: The effect of internal migration on rural populations in Central Java, Indonesia, is analyzed. The focus is on the relationship between the village and the outside world and how it affects the type and patterns of migration that occur. The data were collected in May 1985 in interviews with persons leaving or entering one village.^ieng