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Biomedical subjects

A Dijkstra

Publications and source records attributed to A Dijkstra.

At least 37 records · Page 2Linked to original sources
PubMed1998

Tailored interventions to communicate stage-matched information to smokers in different motivational stages.

Smokers in stages of low readiness to quit (immotives and precontemplators) and smokers in stages of high readiness to quit (contemplators and preparers) were randomly allocated to 1 of 4 tailored intervention conditions offering outcome information, self-efficacy-enhancing information, both sorts of information, or no information. Data on 1,540 smokers, stratified by stage, were analyzed. The primary outcome measure was stage transition. The hypotheses with regard to stage-matched information for immotives and precontemplators were not verified. With regard to contemplators and preparers, the following was found: Compared with the control group, contemplators benefited the most from both sorts of information, whereas preparers benefited the most from self-efficacy-enhancing information only. Comparisons between contemplators and preparers who were assigned to the matched treatment and contemplators and preparers who were assigned to the mismatched treatment supported these findings.

Adult↗
PubMed1998

Tailoring information to enhance quitting in smokers with low motivation to quit: three basic efficacy questions.

Tailoring information to a target individual's features is a promising line of development in self-help interventions. In this article, 752 smokers with explicit low intention to quit were randomly assigned to 1 of 5 conditions: (a) multiple tailored letters with self-help guide, (b) multiple tailored letters only, (c) a single tailored letter with a self-help guide, (d) a single tailored letter only, or (e) a nontailored intervention. Follow-up assessment took place 4 months after the intervention. Results indicated that the single tailored intervention only had no surplus value compared with a nontailored look-alike intervention. The addition of a self-help guide to a tailored intervention was only useful in highly dependent smokers, and multiple tailoring was more effective than single tailoring. It remains important to elucidate why and for whom certain tailored interventions are more effective.

Adult↗
PubMed1998

Interactive image-guided neuroendoscopy: development and early clinical experience.

Technical advances and pioneering surgeons have established neuroendoscopy as an accepted diagnostic and therapeutic tool. The clinical indications for endoscopy, variety of operative techniques and number of endoscopic surgeons continue to increase steadily. However, there are fundamental limits to the scope of freehand endoscopy principally governed by the need for direct vision of anatomical and pathological structures. In addition, whilst the expert neuroendoscopist is only occasionally disorientated by complex distorted anatomy, the rising number of novices are likely to be mislead relatively often. We report the integration of neuroendoscopy with an optical neuronavigation system to provide interactive image-guided neuroendoscopy. This combination both removes the constraining requirement for direct vision and provides accurate localisation to guide the surgeon during surgery. We describe the clinical application of this method to two cases where image-guided endoscopy was essential to the safe completion of the procedure.

Adult↗
PubMed1998

Computerized tailored feedback to change cognitive determinants of smoking: a Dutch field experiment.

In the last decade, attempts have been made to improve the efficacy of minimal interventions by tailoring them to individual features. In the development of these tailored interventions, it is important to know which information in interventions is essential. Most smoking cessation interventions contain information on the outcomes of quitting and skills to be used in a quit attempt. The present study was designed to assess the cognitive changes caused by both sorts of information. Therefore, 246 smokers who were planning to quit within 6 months were randomly assigned to three different conditions. In the first condition, the respondents received a computer-generated tailored letter on the outcomes of smoking cessation. In the second condition, the respondents received a computer-generated tailored letter containing self-efficacy enhancing information, mainly on skills. In both conditions, the contents of the letters were based on the pre-test scores of the participants. Participants in the control condition did not receive any cessation information. The results show that information on the outcomes of quitting changed expected outcomes while information on coping skills changed self-efficacy expectations, in comparison with the control condition. Comparing both experimental conditions, information on the outcomes led to changes in expected outcomes, whereas information on coping skills did not lead to higher self-efficacy expectations than information on the outcomes of quitting. It is concluded that the hypothesized effects were partly verified.

Analysis of Variance↗
PubMed1998

Long-term effectiveness of computer-generated tailored feedback in smoking cessation.

Although tailored interventions consisting of only a few pages of information lead to more quitting than no intervention in the short term, the long-term efficacy of a single tailored intervention still has to be proven. In the present study smokers were reactively recruited and randomly allocated to one of four intervention conditions: (1) outcome information, (2) self-efficacy enhancing information, (3) both sorts of information or (4) no information. Smokers in the three experimental groups received computer-generated tailored feedback containing the condition-specific information, by mail. The results from the 14 months follow-up can be summarized as follows. Compared to the no information condition, all three experimental conditions led to significantly more smokers who had engaged in 24-h quit attempts. However, no experimental condition led to more 7-day quitting than the no information condition. With regard to continuous abstinence, the experimental condition offering a combination of outcome information and self-efficacy enhancing information had a significant effect, compared to the no information condition. It is concluded that a minimal six-page tailored intervention can be beneficial in supporting smokers to quit smoking, even after 14 months.

Adult↗
PubMed1998

Operationalization of the concept of 'nursing care dependency' for use in long-term care facilities.

Nursing care dependency and similar terms are frequently used in nursing literature. However, their meanings are still to be adequately defined. This paper seeks to operationalize the concept of dependency for use in long-term nursing care practice. An analysis of the concept of dependency, specifically with regard to nursing care, will present a frame of reference from which a theoretical definition can be stated. Variable dimensions, observable indicators and means for measuring the indicators are presented. The paper concludes with implications for further research.

Aged↗
PubMed1998

Care dependency and survival among female patients with Alzheimer's disease: a two-year follow-up.

AIM: To investigate the relationship between the severity of the patient's care dependency on the one hand, and causes of death, co-morbidity, and survival on the other, and to find out which of these factors might be longitudinal predictors of survival. METHODS: A two-year follow-up study started in 1994 in the Netherlands. Subjects were 130 female nursing-home patients with Alzheimer's disease (91 severely dependent, and 39 mildly dependent). Features analyzed in 1994 included the scale of care dependency, demographic data, and clinical information. RESULTS: In 1994, both subsamples differed significantly with respect to the duration of Alzheimer's disease, duration of stay, and all nursing-care dependency features, but they did not differ significantly in age, age of disease onset, and co-morbidity. In both groups, the main causes of death were cachexia and/or dehydration. Survival prognosis varied with the level of care dependency. Compared to mildly dependent patients, patients with severe dependency had a 20% higher mortality than expected for the general population of the same age. Marital status, education, cardiovascular disease, and four care dependency features: body posture, day/night pattern, communication, and contact with others, are factors that significantly predict survival. CONCLUSION: Survival prognosis of patients with Alzheimer's disease varies with the level of care dependency.

Activities of Daily Living↗
PubMed1997

Clinical introduction of an adjustable rigid instrument holder for frameless stereotactic interventions.

Interactive image guidance is now in routine use for open neurosurgical procedures and has demonstrated patient benefits. However, freehand interactive guidance is not an appropriate replacement for the traditional frame-based stereotactic procedures of biopsy, electrode placement, and functional lesioning. These point-based procedures require precise target localization and direct instrument guidance to avoid collateral brain injury. To perform true frameless stereotactic procedures requires a guide that is also adjustable for positioning, lockable, and adaptable to multiple instruments. We describe such a device, which is employed for the guidance of biopsy needles, shunts, electrodes, and endoscopes during neuronavigation. The method of frameless stereotactic biopsy retrieval with an infrared-based neuronavigation system is described, clinical results are given, and further areas of application discussed.

Adult↗
PubMed1996

The monofunctional glycosyltransferase of Escherichia coli is a member of a new class of peptidoglycan-synthesising enzymes.

Using conserved fingerprints in the glycosyltransferase (GTase) domain of high-molecular-weight penicillin-binding proteins (PBP), a gene (mgt) encoding a putative monofunctional glycosyltransferase has been identified in Haemophilus influenzae and in other bacteria] species. Here we report the cloning of the homologous Escherichia coli gene and show that the solubilised membrane fraction of E. coli cells overexpressing the mgt gene contain a significantly increased peptidoglycan synthesis activity. In contrast to the high-molecular-weight PBPs, this activity is not inhibited by Flavomycin.

Amino Acid Sequence↗
PubMed1996

Pros and cons of quitting, self-efficacy, and the stages of change in smoking cessation.

In The Netherlands, 34% of the population smoke, and 70% of these smokers are not planning to quit. The lower percentages in the U.S. population seem to reflect a difference in smoking culture. This study analyzes the pros and cons of quitting and self-efficacy expectation in the 5 stages of change in the Dutch population. The results are compared with the pattern of the pros and cons of smoking and self-efficacy expectations found in U.S. samples. The data show the hypothesized pattern: In the first 2 stages, the expected positive outcomes of quitting discriminated better between the stages than self-efficacy, whereas for later stages, self-efficacy was the better discriminator. This study shows that the stage typology is applicable to the Dutch population and that the pattern of the pros, cons, and self-efficacy is very similar to the pattern found in the U.S. populations.

Adult↗
PubMed1996

Nursing-care dependency. Development of an assessment scale for demented and mentally handicapped patients.

This article describing the first phase in the development of an assessment scale of nursing-care dependency (NCD) for Dutch demented and mentally handicapped patients focuses on the background to the study and the content validation of the nursing-care dependency scale. The scale aims to characterize the patients' nursing-care dependency as part of the assessment step in the nursing process, and is based on Henderson's 14 human needs. The Delphi technique, using two panels of experts (n = 44), was applied to reach consensus on significant indicators of nursing-care dependency. The experts' reasoning was used to develop criteria for the assessment of nursing-care dependency. Ultimately, the Delphi rounds generated 15 NCD items with their descriptions and item criteria. There was no fundamental difference between the NCD scales for demented and mentally handicapped patients. Nevertheless, there are two versions of the NCD scale because of the need to apply specific concepts in the nursing care of either population. The original Dutch version of the NCD is also available in English and in Norwegian.

Activities of Daily Living↗
PubMed1995

Gene 19 of plasmid R1 is required for both efficient conjugative DNA transfer and bacteriophage R17 infection.

F-like plasmids require a number of genes for conjugation, including tra operon genes and genes traM and traJ, which lie outside the tra operon. We now establish that a gene in the "leading region," gene 19, provides an important function during conjugation and RNA phage infection. Mutational inactivation of gene 19 on plasmid R1-16 by introduction of two nonpolar stop codons results in a 10-fold decrease in the conjugation frequency. Furthermore, infection studies with the male-specific bacteriophage R17 revealed that the phage is not able to form clear plaques in Escherichia coli cells carrying an R1-16 plasmid with the defective copy of gene 19. The total number of cells infected by phage R17 is reduced by a factor of 10. Both the conjugation- and infection-attenuated phenotypes caused by the defective gene 19 can be complemented in trans by introducing gene 19 alleles encoding the wild-type protein. Restoration of the normal phenotypes is also possible by introduction of the pilT gene encoded by the unrelated IncI plasmid R64. Our functional studies and similarities of protein 19 to proteins encoded by other DNA transfer systems, as well as the presence of a conserved motif in all of these proteins (indicative for a putative muramidase activity) suggest that protein 19 of plasmid R1 facilitates the passage of DNA during conjugation and entry of RNA during phage infection.

Amino Acid Sequence↗
PubMed1994

Expression, purification, and kinetic characterization of the mannitol transport domain of the phosphoenolpyruvate-dependent mannitol phosphotransferase system of Escherichia coli. Kinetic evidence that the E. coli mannitol transport protein is a functional dimer.

The overexpression of the membrane-bound C domain of the mannitol transport protein EIIMtl of Escherichia coli has been achieved. This protein, IICMtl, consisting of the first 346 amino acids, was purified from membrane vesicles and still bound mannitol with a high affinity. Gel filtration experiments showed that purified IICMtl was a dimer, confirming that the interaction within the EIIMtl dimer occurs between the membrane-bound portions of the protein. IICMtl in combination with a chimeric protein consisting of the membrane-bound EIIGlc C domain and the cytoplasmic EIIMtl BA domain could restore both phosphoenolpyruvate-dependent phosphorylation and mannitol/mannitol-P exchange activity. The interaction in this complex was comparable to that of IICMtl with soluble IIBAMtl in as much as there appeared to be no specific interaction between IICMtl and the membrane-bound EIIGlc C domain; the Km of IICMtl for the chimer was so low that saturation could not be achieved. In contrast, a very high affinity with a Km of 2 nM was measured between purified IICMtl and purified EIIMtl. This interaction was manifested in a IICMtl-dependent stimulation of the EIIMtl catalyzed phosphoenolpyruvate-dependent mannitol phosphorylation reaction and the mannitol/mannitol-P exchange reaction. The high affinity of IICMtl for the wild type enzyme can be explained by the formation of heterodimers consisting of a IICMtl monomer and an EIIMtl monomer which interact at the level of the membrane-bound domains. The 2-fold increase in mannitol phosphorylation activity of the hetero- versus homodimer is an indication that the individual subunits in the homodimer are functionally coupled and work at only half their maximum rate. It is known that the EIIMtl dimer, but not the monomer, catalyzes the mannitol/mannitol-P exchange reaction. Since the heterodimer also catalyzes this reaction, it appears that only one functional B domain is required per dimer.

Base Sequence↗
PubMed1993

Expression and characterization of a structural and functional domain of the mannitol-specific transport protein involved in the coupling of mannitol transport and phosphorylation in the phosphoenolpyruvate-dependent phosphotransferase system of Escherichia coli.

The mannitol-specific transport protein in Escherichia coli, EIImtl, consists of three structural and functional domains: a hydrophilic EIII-like domain (the A domain); a hydrophobic transmembrane domain (the C domain); and a second hydrophilic domain (the B domain) which connects the A and C domains together. The A domain contains the first phosphorylation site, His554, while the B domain contains the second phosphorylation site, Cys384. The phosphoryl group which is needed for the active transport of mannitol is sequentially transferred from P-enolpyruvate via the two phosphorylation sites to mannitol bound to the substrate binding site. In this paper, the expression, purification, and initial characterization of the B domain, IIBmtl, are described. Oligonucleotide-directed mutagenesis was used to produce an amber stop codon (TAG) and HindIII restriction site in a flexible loop between the B and A domains in the subcloned gene fragment coding for IIBAmtl (van Weeghel et al., 1991c). The gene fragment coding for IIBmtl was then subcloned behind strong promoters, located in two different expression/mutagenesis vectors, which directed the expression of the 15.3-kDa polypeptide in Escherichia coli. The domain was purified from E. coli crude cell extracts by using Q-Sepharose Fast Flow, S-Sepharose Fast Flow, and hydroxylapatite column steps. This purification procedure resulted in 1 mg of pure IIBmtl/g of cell, wet weight. The purified B domain was analyzed in vitro for its catalytic activity with membranes containing the phosphorylation site mutant form of EIImtl, C384S, and with the transmembrane domain, IICmtl. The B domain, together with purified IIA, was able to restore the P-enolpyruvate-dependent phosphorylation activity of the membrane-bound C domain. Steady-state mannitol phosphorylation kinetics at saturating EI, HPr, and IIAmtl yielded an apparent Km of P-IIBmtl for IICmtl of 200 microM and an apparent Vmax of 71 nmol of mtl-P min-1 mg of membrane protein)-1. This Vmax value is comparable to that of wild-type EIImtl measured under the same experimental conditions.

Base Sequence↗
PubMed1993

Presence of protein constituents of the gram-positive bacterial phosphotransferase regulatory system in Acholeplasma laidlawii.

Acholeplasma species have been reported to lack a functional phosphoenolpyruvate:sugar phosphotransferase system (PTS). We show here that Acholeplasma laidlawii possesses activities of enzyme I, HPr, HPr(ser) kinase, and HPr(ser-P) phosphatase but lacks detectable activities of enzymes II of the PTS. HPr from this organism was purified, and the regulatory properties of the kinase and phosphatase were characterized and shown to differ from those of previously studied bacteria. The results suggest the presence of an incomplete PTS in A. laidlawii which has the potential to function in a unique regulatory capacity.

Acholeplasma laidlawii↗
PubMed1992

Enzymatic preparation of 1,6-anhydro-muropeptides by immobilized murein hydrolases from Escherichia coli fused to staphylococcal protein A.

In order to produce biologically active 1,6-anhydro-muropeptides in large amounts by enzymatic degradation of isolated bacterial murein polymer highly specific periplasmic murein-metabolizing enzymes from Escherichia coli are made available. The genes slt, dacB, and mepA, encoding the soluble lytic transglycosylase (Slt), the penicillin-sensitive DD-endopeptidase (PBP4), and the penicillin-insensitive murein endopeptidase A (MepA), were independently fused to the N-terminal encoding sequence of staphylococcal protein A (SpA) under control of the temperature-inducible phage lambda pR promoter. The SpA fusion proteins were stably over-produced at high levels in E. coli upon temperature induction at 42 degrees C and account for 3% (5 mg SpASlt/l culture), 3% (5 mg SpAPBP4/l culture), and 0.3% (0.5 mg SpAMepA/l culture) of total protein. The SpA fusion proteins, immobilized on IgG Sepharose, are proteolytically sensitive, in vitro, resulting in complete degradation of the SpA portion of the fusion proteins and release of the murein hydrolases in intact and enzymatically active form into the supernatant. Proteolytic degradation could be prevented by p-hydroxymercuribenzoic acid (PHMB) or ethylenediaminetetraacetate (EDTA) suggesting the involvement of the periplasmic protease Pi from E. coli. The immobilized fusion proteins were enzymatically active and could be used for the batch production of biologically active 1,6-anhydro-muropeptides, which were successively separated on HPLC. Isolated murein polymer was degraded quantitatively to monomeric 1,6-anhydro-muropeptides when immunoglobulin G (IgG)-SpASlt was used in combination with IgG-SpAMepA. A combination of IgG-SpASlt with IgG-SpAPBP4 left the 1,6-anhydro-dimers and oligomers being cross-linked via an LD-peptide bond (m-DAP-m-DAP) uncleaved.

Amino Acid Sequence↗
PubMed1992

Safety effects of 30 Km/H zones in The Netherlands.

Since 1983, Dutch municipal authorities can institute a maximum speed of 30 km/h on roads or in zones within built-up areas. The safety effects of 30 km/h zones are supposed to be positive. In order to be sure about this, the Ministry of Transport has stimulated 15 municipalities to implement a 30 km/h zone and set up an evaluation of the safety effects of these zones. The evaluation research is coordinated by the Institute for Road Safety Research (SWOV). The evaluation concerns the changes in traffic flows, opinions of residents, conflicts, and accidents. This paper gives the results of the evaluation.

Accidents, Traffic↗