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Biomedical subjects

A J Schmidt

Publications and source records attributed to A J Schmidt.

At least 19 recordsLinked to original sources
PubMed1999

Psychometric properties of the Multidimensional Pain Inventory, Dutch language version (MPI-DLV).

The purpose of this study was to investigate the psychometric properties of a Dutch translation of the Multidimensional Pain Inventory, MPI-DLV. Data was available on 733 chronic pain patients. There were three issues of special interest. The first one related to the comparability between the MPI-DLV and the American and German MPI versions with regard to the psychometric aspects. The second dealt with the construct validity of the MPI-DLV scale 'general activity'. It was predicted that patients with high scores on this scale would be in better physical condition, as measured on a working-to-tolerance bicycle ergometer test. In relation to the third issue, attention was given to the factor-invariance between fibromyalgia patients and back pain patients. From the results obtained it was concluded that (1) the factorial structure of the three MPI parts is replicated and the reliability estimates and validity indicators are similar to those from the American and German versions; (2) patients with high scores on the 'general activity' scale are in better physical condition and (3) MPI-DLVs of fibromyalgia and back pain patients do have similar factorial structures. Evidence was also obtained that the MPI-DLV is sensitive to treatment changes. Applications of the MPI-DLV are discussed.

Adult↗
PubMed1999

Computed tomographic angiography: historical perspective and new state-of-the-art using multi detector-row helical computed tomography.

Since its clinical introduction in 1991, volumetric computed tomography scanning using spiral or helical scanners has resulted in a revolution for diagnostic imaging. In addition to new applications for computed tomography, such as computed tomographic angiography and the assessment of patients with renal colic, many routine applications such as the detection of lung and liver lesions have substantially improved. Helical computed tomographic technology has improved over the past eight years with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms, but the greatest advance has been the recent introduction of multi detector-row computed tomography scanners. These scanners provide similar scan quality at a speed gain of 3-6 times greater than single detector-row computed tomography scanners. This has a profound impact on the performance of computed tomography angiography, resulting in greater anatomic coverage, lower iodinated contrast doses, and higher spatial resolution scans than single detector-row systems.

Angiography↗
PubMed1997

Validating the MPI-DLV using experience sampling data.

The present study investigates the relationship between scale scores on the Dutch version of the Multidimensional Pain Inventory (MPI-DLV) and data derived from comparable items from an experience sampling procedure. Fifty-seven chronic pain patients participated in the study, which lasted 6 consecutive days. Special attention was given to the relationship between the MPI-DLV pain intensity score and the mean experience sampling pain intensity score. Significant correlations were found between the MPI-DLV scales Pain Severity, Interference, Solicitous, Punishing and Distracting Responses, and Household Chores and their experience sampling analogues. A marginally significant correlation was found with regard to the MPI-DLV Life Control scale. The General Activity and Affective Distress scales had no relationship with the analogous experience sampling items. The significant correlations were regarded as further validation of the MPI-DLV. A regression analysis revealed that 58% of the variance of the experience sampling pain intensity score could be explained by the MPI-DLV present pain intensity item score.

Adult↗
PubMed1996

CT-guided percutaneous biopsy of pancreas transplants.

PURPOSE: To evaluate the safety and efficacy of computed tomography (CT)-guided percutaneous needle biopsy in pancreas transplantation patients with graft dysfunction. MATERIALS AND METHODS: Sixty-three CT-guided core biopsies of 42 pancreas grafts were performed with 18-gauge needles over a 38-month period. All but one of the transplants were bladder-drained allografts. An average of 2.25 passes (range, 1-4) per allograft were made, and tissue was immediately processed for histopathologic examination. Fifteen patients (19% of biopsy referrals) could not undergo biopsy because a safe approach was not available. RESULTS: Of the 63 biopsy specimens, 57(90%) were adequate for histopathologic diagnosis, which was normal or no specific abnormality in 14, acute rejection in 20, chronic rejection in one, chronic rejection with cytomegalovirus inclusion bodies in one, acute or chronic pancreatitis in 13, chronic pancreatitis with cytomegalovirus inclusion bodies in one, and miscellaneous in seven. Three specimens contained no pancreatic tissue, and three were insufficient for diagnosis. Minor complications included a transient rise in serum amylase levels in four patients (6%) and transient mild hematuria in one patient (1%). The only major complication (substantial hemorrhage) occurred in two cases (3%). CONCLUSION: CT-guided percutaneous needle biopsy is a safe, alternative method for obtaining tissue in pancreas transplantation patients with graft dysfunction. It may obviate cystoscopic biopsy for bladder-drained grafts or open biopsy in duct-injected or enteric-drained grafts.

Adolescent↗
PubMed1996

Hypochondriasis and symptom reporting--the effect of attention versus distraction.

BACKGROUND: This study examined symptom perception in hypochondriacal patients without physical stimulation. METHODS: Seventeen outpatients with DSM-III-R hypochondriasis and 16 healthy control subjects were compared. All subjects were asked to report perceived sensations in three conditions: attention, distraction and control. RESULTS: It was found that hypochondriacal subjects showed remarkably higher levels of symptom reporting than healthy subjects in all three conditions. In spite of excessive attention to bodily sensations in a control condition, attention instructions still added significantly to symptom reporting in hypochondriacal patients. The effect of distraction was not significant in either of the groups. Furthermore, group differences in symptom reporting appeared to be related to preoccupation with bodily symptoms rather than to general anxiety level as measured by the STAI. CONCLUSIONS: Hypochondriacal patients report more bodily sensations than healthy controls when no instructions are given. In addition, focussing on bodily sensations seems to cause a significant overall increase of perceived symptoms in hypochondriacal patients, whereas in healthy subjects there is a trend towards an increase in symptom reporting.

Adult↗
PubMed1996

Operant conditioning of the pain experience.

Two experiments were carried out to study operant conditioning of pain report. Further, it was investigated whether pain-related psychophysiological and psychological measures (skin conductance response and magnitude matching) could also be conditioned operantly. In both experiments subjects received 12 painful electric shocks of equal intensity. In Exp. 1 healthy subjects were assigned to either a control group or an up-conditioning group. Up-conditioning occurred by verbally rewarding increases in pain report and punishing decreases. Analyses indicated that up-conditioning of both pain report and the pain-related psychophysiological measures succeeded. To rule out alternative explanations of the results (attention shift towards pain and conditioning of anxiety) the verbal punishments were adjusted in Exp. 2. A down-conditioning group was also added. The attempt to replicate the results of Exp. 1 failed and down-conditioning of the pain report could not be established. These inconsistent results are most probably due to modified punishment of responses. The consequences for the results of Exp. 1 are discussed. Based on the results of post hoc analyses, some suggestions are made for operant conditioning studies of pain.

Adolescent↗
PubMed1994

Psychological mechanisms in hypochondriasis: attention-induced physical symptoms without sensory stimulation.

Attention and expectancy have, in previous research, been demonstrated to influence symptom reporting and these findings can be relevant for understanding hypochondriasis. Earlier attention/expectancy effects on symptom reporting were studied when subjects were physically stimulated by the experimenter. If attention or expectancy produced symptom reporting, which plays a role in hypochondriasis, one expects that attention/expectancy will also produce symptoms in the absence of any deliberate physical stimulation. Eighty healthy volunteers were allocated to one of four groups: attention, expectancy, attention plus expectancy or a control condition. Compared to the control condition there was much higher symptom reporting in the 3 experimental groups. The experimental groups did not differ. It is argued that the effects of expectancy are obtained via increased attention. The relevance of the findings for understanding hypochondriasis is discussed.

Adult↗
PubMed1993

Hypochondriasis in ENT practice.

In this study the incidence of hypochondriasis among new ENT out-patients was investigated. A validated questionnaire, which was administered twice with an interval of 3 months, was used to make the diagnosis. Medical information also played a part in the assessment. The diagnosis hypochondriasis applied to 13% of the patients who completed the entire diagnostic procedure. This group made very frequent use of a range of medical services and took a large amount of medicine. Compared with the non-hypochondriacal ENT group, the hypochondriacal group had a more negative opinion about their own health, although those in the latter group were less ill, measured by objective criteria. In order to be able to diagnose hypochondriasis in ENT practice, psychological or psychiatrical consultation is necessary.

Adolescent↗
PubMed1993

Activity loss of glutathione synthesis enzymes associated with human subcapsular cataract.

PURPOSE: To assess the activities of the two enzymes required for glutathione synthesis, gamma-glutamylcysteine synthetase and glutathione synthetase, in various forms of human cataracts. METHODS: The Cooperative Cataract Research Group cataract classification method and standard enzyme assay procedures were used. RESULTS: An inverse relationship was shown between residual activity of each of the glutathione synthesis enzymes and degree of subcapsular cataract. A weaker inverse relationship existed between glutathione synthetase activity and supranuclear and nuclear cataracts. No other parameters yielded comparable correlations with the activity of either enzyme. CONCLUSIONS: Activity loss of the glutathione synthesis enzymes is associated with human subcapsular cataract formation.

Aged↗
PubMed1992

Differences in pain perception and sensory discrimination between chronic low back pain patients and healthy controls.

Pain perception threshold (PPT), maximal pain tolerance (MPT) and pain discrimination of CLBP patients and controls were tested. Pain perception threshold was significantly higher in the patient group for two different pain stimuli (electrical and pressure pain). Maximal pain tolerance was significantly higher in CLBP patients only for the pressure pain stimulus. There was no difference between the groups in their capacity to discriminate between painful stimuli of different intensity, as measured by a forced-choice task. It is concluded that CLBP patients have a decreased sensitivity for experimental pain. Two theories which might explain this decreased sensitivity are discussed.

Adult↗
PubMed1991

Psychophysiological responses to repeated acute pain stimulation in chronic low back pain patients.

Psychophysiological recordings (electrodermal activity, heart rate, respiration rate and frontalis and back muscle tension) were taken in chronic low back pain (CLBP) patients and control subjects during baseline conditions and during the presentation of six acute pressure pain stimuli. No baseline differences in back muscle tension between CLBP patients and controls were found, but CLBP patients did have higher baseline electrodermal activity. During pain stimulation, CLBP patients showed larger skin conductance reactions than controls. Also, the CLBP patient group showed a marked increase in lumbar muscle tension during the test compared to baseline, whereas the EMG level of the control group remained unchanged. This increase in muscle tension seemed to be more related to the postural change than to the pain stimulus, and it is hypothesized that some CLBP patients react with exaggerated and non-functional back muscle contractions to slight changes in posture. Contrary to expectation, no differences were found between CLBP patients and controls in physiological habituation after repeating the pain stimulus. Comparison of subjective pain ratings and psychophysiological variables showed that for control subjects arousal and subjective pain were related. For CLBP patients there was no such clear relationship.

Adult↗
PubMed1991

Regulation of phosphatidylglycerolphosphate synthase in Saccharomyces cerevisiae by factors affecting mitochondrial development.

Phosphatidylglycerolphosphate synthase (PGPS; CDP-diacylglycerol glycerol 3-phosphate 3-phosphatidyltransferase; EC 2.7.8.5) catalyzes the first step in the synthesis of cardiolipin, an acidic phospholipid found in the mitochondrial inner membrane. In the yeast Saccharomyces cerevisiae, PGPS expression is coordinately regulated with general phospholipid synthesis and is repressed when cells are grown in the presence of the phospholipid precursor inositol (M. L. Greenberg, S. Hubbell, and C. Lam, Mol. Cell. Biol. 8:4773-4779, 1988). In this study, we examined the regulation of PGPS in growth conditions affecting mitochondrial development (carbon source, growth stage, and oxygen availability) and in strains with genetic lesions affecting mitochondrial function. PGPS derepressed two- to threefold when cells were grown in a nonfermentable carbon source (glycerol-ethanol), and this derepression was independent of the presence of inositol. PGPS derepressed two- to fourfold as cells entered the stationary phase of growth. Stationary-phase derepression occurred in both glucose- and glycerol-ethanol-grown cells and was slightly greater in cells grown in the presence of inositol and choline. PGPS expression in mitochondria was not affected when cells were grown in the absence of oxygen. In mutants lacking mitochondrial DNA [( rho0] mutants), PGPS activity was 30 to 70% less than in isogenic [rho+] strains. PGPS activity in [rho0] strains was subject to inositol-mediated repression. PGPS activity in [rho0] cell extracts was derepressed twofold as the [rho0] cells entered the stationary phase of growth. No growth phase derepression was observed in mitochondrial extracts of the [rho0] cells. Relative cardiolipin content increased in glycerol-ethanol-grown cells but was not affected by growth stage or by growth in the presence of the phospholipid precursors inositol and choline. These results demonstrate that (i) PGPS expression is regulated by factors affecting mitochondrial development; (ii) regulation of PGPS by these factors is independent of cross-pathway control; and (iii) PGPS expression is never fully repressed, even during anaerobic growth.

Anaerobiosis↗
PubMed1989

Environmental and interoceptive influences on chronic low back pain behavior.

The operant conditioning theory states that environmental stimuli greatly influence chronic pain behavior. In contrast, the hypochondriasis theory states that pain behavior is the result of an intensified pain perception which is part of a more general augmentation and amplification of normal bodily sensations. The operant theory predicts that pain behavior (operationalized as poorer endurance on the part of chronic low back pain patients as compared to the endurance of control subjects in a series of 6 working-to-tolerance treadmill tests) will decrease when no verbal or non-verbal feedback for treadmilling behavior is given. This hypothesis could not be confirmed in the present study. The hypochondriasis theory predicts that chronic pain patients will report more bodily sensations, both at rest and after treadmill exercises. This hypothesis was strongly supported by the findings of the present study.

Adult↗
PubMed1987

Psychological research and chronic low back pain: a stand-still or breakthrough?

Some of the main psychological research topics concerning chronic low back pain (CLBP) are critically discussed. These topics include: 1. research aimed at describing a specific low back pain personality profile, 2. research into the predictability of therapy results on the basis of psychological assessment, and 3. outcome research of psychologically-oriented treatment for CLBP. It is concluded that these topics provide little insight into the role of psychological factors in the development and maintenance of CLBP. Based on the few empirical studies available, some new and promising directions for future research are proposed, aimed at gaining a better insight into the CLBP syndrome itself. Discussed are: 1. Risk factors in the transition from acute to chronic LBP, 2. the deviant sensitivity to acute, experimental pain stimuli of CLBP patients, 3. the relationship between CLBP behavior and psychophysiologic variables, 4. determinants of CLBP behavior, with special attention to endurance, 5. the deviant processing of proprioceptive stimuli, and 6. the implementation for chronic pain of the unpredictability and uncontrollability paradigms. The emphasis in the presentation of these new topics is more on raising questions than on answering them.

Back Pain↗
PubMed1986

Persistence behavior of chronic low back pain patients in an acute pain situation.

The test behavior of 24 chronic low back pain patients was compared with the behavior of 24 healthy control Ss., matched for age and sex, in an experimental, acute pain situation (cold pressor-test). Chronic low back pain patients showed poorer persistence behavior and reported more pain. Thus, elements of typical chronic low back pain behavior were also present in an acute pain situation. These findings are discussed within the framework of stimulus-generalization theory. In addition, the effect of different coping strategies on pain tolerance was reconfirmed. The chronic low back pain group and the control group did not cope differently.

Acute Disease↗
PubMed1985

Cognitive factors in the performance level of chronic low back pain patients.

An experimental group of 39 chronic low back pain (CLBP) patients and an equal number of controls, matched for age and sex, completed questionnaires of self-concept and performance motivation. SS were also tested on a standardized back-stress physical test carried out with low external information and feedback. The results revealed a strong tendency for CLBP patients to have a negative self-concept, confirming the findings of previous research. Poorer performance of the CLBP patients on the physical test measure of behavioural persistence and on physiological measures were unrelated to reported pain level or to poor physical condition. Compared to the controls, the chronic low back pain group was less able to estimate their physiological level of exertion, being inclined to overrate their actual individual effort. The interaction of a negative self-concept and negative expectations is discussed.

Achievement↗
PubMed1985

Performance level of chronic low back pain patients in different treadmill test conditions.

An experimental group of 39 chronic low back pain (CLBP) patients and an equal number of control subjects matched for age and sex were tested with a standardized back stress physical test. The subjects were given no indication of the performance expected and no feedback was given during the test. The test was repeated with a high frame of reference and feedback offered to the subjects. In the latter condition the control group improved their performance in contrast to the CLBP group. The poorer performance of the CLBP patients in both conditions was unrelated to pain increase, post-test pain level or poor physical condition. However, there is a clear relationship between performance and pre-test pain level, especially in the feedback condition. In this condition, it also seems that increasing pain level during the test is used as a 'rationalization' for the built-in failure experience. Compared to the control group the CLBP patients were less able to estimate their physiological level of exertion and were inclined to overrate their actual effort.

Adult↗