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B Bonke

Publications and source records attributed to B Bonke.

At least 19 recordsLinked to original sources
PubMed2006

Calculating risk changes after negative mutation test outcomes for autosomal dominant hereditary late-onset disorders.

We demonstrate, in a specific scenario, the effect of negative test results from relatives in families at risk for an autosomal dominant hereditary late-onset disorder. A hypothetical pedigree, of a family at risk of Huntington's disease, was used to demonstrate the consequences for the risk status of various family members in the case where relatives have been tested, and found to be mutation negative. We argue that accurate assessment of conditional probabilities in clinical genetics is important for individuals at risk for hereditary disorders with Mendelian transmission patterns; our formulae offer the opportunity -- when simplifying assumptions are met -- to determine the changed risk status of individuals in such cases.

Age of Onset↗
PubMed2003

[Ethnic and religious diversity of first year medical students at the Erasmus University Medical Center, Rotterdam].

OBJECTIVE: To obtain information on the ethnic, religious and socio-cultural diversity of first-year medical students at the University Medical Center Rotterdam, the Netherlands. DESIGN: Anonymous questionnaire. METHOD: In December 2001, first-year medical students were given a questionnaire during a compulsory practical class. In the processing of the result, use was made of Statistics Netherlands' classification of allochthonous persons. Data were also collected on the student's mother tongue, self-reported command of Dutch and other languages, religious denomination and the education of their parents. RESULTS: The response rate was 90% (277/308); 175 women and 102 men. Seventy-four percent of respondents were rated as 'autochthonous' (both parents born in the Netherlands), 8% as 'western allochthonous' (at least one parent born in another western country) and 18% as 'non-western allochthonous' (at least one parent born in a non-western country). 'Allochthonous' students originated from 30 different countries, most frequently Surinam (n = 15), and spoke 26 different languages. Of the 'western allochthonous' students 70% considered themselves to be 'ethnic Dutch', of the 'non-western allochthonous' 65% considered themselves to be both Dutch and 'allochthonous'. Fifteen students did not speak Dutch with their parents and rated their command of Dutch to be significantly lower (score 8.9; scale 0-10) than that of the others. Forty-eight percent of the respondents did not consider themselves to be a member of any religious denomination, 18% were Protestant, 15% Roman Catholic and 7% Muslim. For 60% of the respondents, at least one parent had finished higher education. Parents of ethnic Turkish and Moroccan students had a significantly lower education than parents in all other groups.

Adolescent↗
PubMed2001

Auditory information processing during adequate propofol anesthesia monitored by electroencephalogram bispectral index.

UNLABELLED: Memory for intraoperative events may arise from inadequate anesthesia when the hypnotic state is not continuously monitored. Electroencephalogram bispectral index (BIS) enables monitoring of the hypnotic state and titration of anesthesia to an adequate level (BIS 40 to 60). At this level, preserved memory function has been observed in trauma patients. We investigated memory formation in elective surgical outpatients during target-controlled propofol anesthesia supplemented with alfentanil. While BIS remained between 40 and 60, patients listened to a tape with either familiar instances (exemplars) from two categories (Experimental [E] group, n = 41) or bird sounds (Control [C] group, n = 41). After recovery, memory was tested directly and indirectly. BIS during audio presentation was on average (+/- SD) 44 +/- 5 and 46 +/- 5 for Groups E and C, respectively. No patient consciously recalled the intraoperative period, nor were presented words recognized reliably (Group E, 0.9 +/- 0.8 hits; Group C, 0.8 +/- 0.8 hits) (P = 0.7). When asked to generate category exemplars, Group E named 2.10 +/- 1.0 hits versus 1.98 +/- 1.0 in Group C (P = 0.9). We found no explicit or implicit memory effect of familiar words presented during adequate propofol anesthesia at BIS levels between 40 and 60 in elective surgical patients. IMPLICATIONS: This study suggests that stable levels of adequate hypnosis may prevent information processing and memory formation during general anesthesia and supports the feasibility of electroencephalogram bispectral index as a monitor of adequate anesthesia.

Acoustic Stimulation↗
PubMed2000

Evaluation of techniques for the presentation of laboratory data: support of pattern recognition.

Two tabular and two graphical techniques for the presentation of laboratory test results were compared in a reaction-time experiment with 22 volunteers. The experimental setup was designed to determine whether one or more of the presentation techniques facilitated the recognition of four predefined combinations of abnormal test results. Using a conventional, tabular presentation technique as a reference, faster median response times were obtained with each of the other three presentation techniques, irrespective of pattern. The effect on accuracy was less clear, possibly due to the small number of errors made.

Clinical Laboratory Information Systems↗
PubMed1998

When seemingly irrelevant details matter: hidden covariation detection reexamined.

Hidden covariation detection (HCD) theory states that when personality characteristics are surreptitiously associated with irrelevant features, these features obtain heuristic value for future evaluations of personality characteristics. According to the theory, subjects are not consciously aware of using such heuristics in their evaluations. We tested these hypotheses by confronting participants with statements that were said to belong to separate individuals, in which the apparent level of intelligence was associated with an irrelevant feature of the person who allegedly made these statements. In line with HCD theory, participants appeared to use this association, unconsciously, to guide their subsequent evaluations. Implications of these findings for HCD theory are discussed.

Adult↗
PubMed1997

The influence of psychological variables on postoperative anxiety and physical complaints in patients undergoing lumbar surgery.

Previous research has indicated that postoperative distress is influenced by diverse biographic, medical and psychological variables, such as personality, coping behaviours and anxiety. The influence of state variables, apart from anxiety and coping behaviour, has received scant attention. Furthermore, the influence of coping behaviour has remained unclear. The present study investigated coping behaviour and indications of physical distress, i.e., preoperative fatigue, leg pain and back pain, besides preoperative anxiety, as predictors of postoperative anxiety and physical complaints in 126 patients undergoing lumbar surgery. Preoperative anxiety and leg pain independently predicted more postoperative anxiety beyond the influence of age, sex and medical variables. Preoperative anxiety and fatigue independently predicted more postoperative physical complaints. No associations were found between the coping behaviours and the postoperative variables. The implications of these results are discussed in relation to intervention strategies aimed at diminishing the stress of surgery.

Adaptation, Psychological↗
PubMed1997

Evaluation of techniques for the presentation of laboratory data. I: Time needed for interpretation.

Four tabular and two graphical techniques for the presentation of laboratory test results were evaluated in a reaction-time experiment with 25 volunteers. Artificial variables and values were used to represent sets of 12 laboratory tests to eliminate the possible effects of clinical experience. Analyses focused on reaction times for correctly classified sets of data. For comparable data sets, Presentation Techniques (PT) that use color, always allow faster interpretation than PTs that do not use color, or use only a simple marker. Color-coded tables yielded an improvement in median reaction time of approximately six times or better, as compared to the reference PT (a tabular PT without any hints). For the color-coded graphs, the improvement rate was approximately 2.5 or better.

Clinical Laboratory Techniques↗
PubMed1997

Evaluation of techniques for the presentation of laboratory data. II: Accuracy of interpretation.

Four tabular and two graphical techniques for the presentation of laboratory test results were evaluated in a reaction time experiment with 25 volunteers. Artificial variables and values were used to represent sets of 12 laboratory tests to eliminate the possible effects of clinical experience. Analyses focused on four types of errors in interpretation. Color-coded tables and one of the color-coded graphs greatly (2.8 times or better) reduced the number of incorrectly classified test results, as compared to the reference presentation technique. This was mainly due to a reduction of the number of abnormal test results that were not noticed by the subjects when using these presentation techniques.

Clinical Laboratory Techniques↗
PubMed1996

Memory during general anesthesia: practical and methodological aspects.

Evidence coming from several studies into memory and awareness during general anesthesia suggests that in surgical patients who seem to be adequately anesthetized (i.e., unaware of what happens in the operating theater), some form of cognitive functioning is preserved. This finding has important implications both for clinical practice and for memory research. In order to give the methodological background of the present situation in this field of research, this article deals, on the basis of recent experiments, with important methodological aspects of studies into perception and memory during general anesthesia.

Anesthesia, General↗
PubMed1996

Therapeutic suggestion has not effect on postoperative morphine requirements.

This study was designed to confirm the effect of therapeutic intraoperative auditory suggestion on recovery from anesthesia, to establish the effect of preoperative suggestion, and to assess implicit memory for intraoperative information using an indirect memory task. Sixty consenting unpremedicated patients scheduled for elective gynecologic surgery were randomly divided into three equal groups: Group 1 received a tape of therapeutic suggestions preoperatively, and the story of Robinson Crusoe intraoperatively; Group 2 heard the story of Peter Pan preoperatively and therapeutic suggestions intraoperatively; Group 3 heard the Crusoe story preoperatively and the Peter Pan story intraoperatively. A standardized anesthetic technique was used with fentanyl, propofol, isoflurane, and nitrous oxide. After surgery, all patients received patient-controlled analgesia (PCA) with a standardized regimen. In the 24 h postsurgery, morphine use was recorded every 6 h and at 24 h an indirect memory test (free association) was used to test for memory of the stories. Anxiety scores were measured before surgery and at 6 and 24 h postsurgery. There were no significant differences between groups for postoperative morphine use, pain or nausea scores, anxiety scores, or days spent in hospital after surgery. Seven of 20 patients who heard the Pan story intraoperative gave a positive association with the word "Hook," whereas 2 of 20 who did not hear the story gave such an association. Indirect memory for the Pan story was established using confidence interval (CI) analysis. (The 95% CI for difference in proportion did not include zero). No indirect memory for the Crusoe story could be demonstrated. This study did not confirm previous work which suggested that positive therapeutic auditory suggestions, played intraoperatively, reduced PCA morphine requirements. In contrast, a positive implicit memory effect was found for a story presented intraoperatively.

Adult↗
PubMed1996

Processing familiar and unfamiliar auditory stimuli during general anesthesia.

We tested memory priming for auditory stimuli presented during general propofol-sufentanil anesthesia in 58 patients undergoing day-case arthroscopic surgery. Stimuli were presented via headphones and consisted of common facts (Group A, 29 patients), or familiar or unfamiliar full names of fictitious people (GRoup B, 29 patients). Group A was expected to give more correct answers to questions about the common facts than Group B, when tested postoperatively, and Group B to attribute more fame to presented names than Group A (famous names test). Because the process for learning new or unfamiliar stimuli (elaboration) in particular may be impaired under general anesthesia, more memory priming was expected for familiar than for unfamiliar material. No significant differences were demonstrated between the two groups in performance on common facts or in fame attributed to the names. The amount of memory priming, however, was positively related to one of two measures of preoperative anxiety.

Acoustic Stimulation↗
PubMed1996

Information processing during general anesthesia: evidence for unconscious memory.

Memory for words presented during general anesthesia was studied in two experiments. In Experiment 1, surgical patients (n = 80) undergoing elective procedures under general anesthesia were presented shortly before and during surgery with words via headphones. At the earliest convenient time after surgery (within 5 h) and 24 h later, memory was tested by asking patients to complete auditorily presented word stems with the first word that came to mind and to leave out words they remembered having heard earlier (exclusion task). Moreover, patients were requested to perform a "yes/no" forced-choice recognition task to assess recognition memory for both the pre- and intraoperative words. Memory for the material presented during anesthesia was demonstrated immediately after surgery and 24 h later by means of both tasks. In a second similar experiment (n = 80), the results were replicated. These findings show that anesthetized patients can process information that was presented intraoperatively.

Adolescent↗
PubMed1995

The Multidimensional Fatigue Inventory (MFI) psychometric qualities of an instrument to assess fatigue.

The Multidimensional Fatigue Inventory (MFI) is a 20-item self-report instrument designed to measure fatigue. It covers the following dimensions: General Fatigue, Physical Fatigue, Mental Fatigue, Reduced Motivation and Reduced Activity. This new instrument was tested for its psychometric properties in cancer patients receiving radiotherapy, patients with the chronic fatigue syndrome, psychology students, medical students, army recruits and junior physicians. We determined the dimensional structure using confirmatory factor analyses (LISREL's unweighted least squares method). The hypothesized five-factor model appeared to fit the data in all samples tested (AGFIs > 0.93). The instrument was found to have good internal consistency, with an average Cronbach's alpha coefficient of 0.84. Construct validity was established after comparisons between and within groups, assuming differences in fatigue based on differences in circumstances and/or activity level. Convergent validity was investigated by correlating the MFI-scales with a Visual Analogue Scale measuring fatigue (0.22 < r < 0.78). Results, by and large, support the validity of the MFI.

Adult↗
PubMed1995

Implicit memory performance of patients with Alzheimer's disease: a brief review.

Memory can be assessed with either explicit or implicit tasks. Implicit memory tasks, in contrast with explicit tasks, do not refer to conscious recollection of a previous learning experience. Implicit memory is revealed by a change in task performance that can be attributed to previous learning. Amnesic patients perform poorly on explicit memory tasks, but exhibit normal performance on implicit tasks. Recently, researchers have studied the implicit memory performance of patients with Alzheimer's disease. This article aims to give an overview of the performance of Alzheimer patients on four tasks of implicit memory. Compared with normal elderly controls, patients with Alzheimer's disease seem to demonstrate impaired performance on conceptual, but not on perceptual, implicit memory tasks. This dissociation could yield important information about the neurologic systems subserving implicit memory processes. Some suggestions for future research into the implicit memory of Alzheimer patients are given.

Aged↗
PubMed1995

Assessment of preoperative anxiety: comparison of measures in patients awaiting surgery for breast cancer.

We have compared three measurements of anxiety to determine their equivalence in assessing anxiety before surgery. Forty-four patients awaiting breast cancer surgery completed the state scale of the state-trait anxiety inventory (STAI), the hospital anxiety and depression scale (HAD) and a 100-mm visual analogue scale (VAS). Analysis restricted to correlations between the scales gave the misleading impression that VAS scores were inconsistent with those of the HAD and STAI. However, when scores were considered in relation to normative cut-off values to categorize anxiety levels, the three scales showed good agreement. We conclude that the scales were equivalent in their assessment of anxiety before surgery, but that reference to normative data was important in establishing such equivalence and in determining the patient's state.

Adult↗
PubMed1995

The effect of midazolam premedication on implicit memory activation during alfentanil-nitrous oxide anaesthesia.

Eighty-three patients were given midazolam 0.1 mg.kg-1 by intramuscular injection as premedication before general anaesthesia with alfentanil-nitrous oxide. During anaesthesia patients were presented (through headphones) with either statements about common facts of some years ago (group A) (n = 43) or new verbal associations, e.g. names of fictitious, nonfamous people (group B) (n = 40). In a previous study with the same anaesthetic technique, but without premedication there was significant activation of implicit memory (p < 0.001). In this study we found no explicit or implicit memory for the auditory information presented during anaesthesia. Midazolam premedication can prevent implicit memory activation during alfentanil-nitrous oxide anaesthesia.

Adult↗