Biomedical subjects

A H Zwinderman

Publications and source records attributed to A H Zwinderman.

At least 253 records · Page 14Linked to original sources

PubMed1993

Preparation of the colon for single- and double-contrast barium enema examination: a simplified method.

A commercially available prepackaged liquid diet was prescribed to 112 patients to use in combination with laxatives in a 1-day preparation regimen before single- and double-contrast barium enema examination. Cleansing enemas were not performed before the examination. Colon radiographs were evaluated with regard to amount of residual stool, mucosal detail, coating, and overall quality. Results were excellent in 92% (103 of 112) of patients and fair in 5% (six of 112). Cleansing enemas can be avoided through use of this preparation protocol.

Adolescent↗

PubMed1993

Neutral endopeptidase activity and airway hyperresponsiveness to neurokinin A in asthmatic subjects in vivo.

In a previous study we have shown that inhibition of the endogenous neuropeptide-degrading enzyme, neutral endopeptidase (NEP), potentiates airway narrowing to neurokinin A (NKA) in normal humans in vivo. In the present study, we tested the hypothesis that hyperresponsiveness to NKA in asthma is caused by a reduction in endogenous NEP activity. To that end, we used the NEP inhibitor, thiorphan, or placebo as inhaled pretreatment to NKA challenge in eight atopic asthmatic men, who were controlled by on-demand usage of beta 2-agonists alone. The dose of thiorphan pretreatment was obtained from pilot experiments in which 0.5 ml of a 2.5-mg/ml concentration appeared to be the maximally effective nebulized dose. Dose-response curves to inhaled NKA (1 to 125 micrograms/ml, 0.5 ml/dose) were recorded on 2 randomized days 1 wk apart, in a cross-over study. To detect any effects of thiorphan on bronchoconstriction per se, we also investigated the effect of thiorphan or placebo on the dose-response curve to inhaled methacholine in a separate set of experiments. The response was measured by FEV1 and by partial expiratory flow-volume curves (V40p). The position of the dose-response curves was expressed as the concentration causing a 20% fall in FEV1 (PC20FEV1) or a 40% fall in V40p (PC40V40p). Baseline FEV1 and V40p were not affected by either pretreatment (p > 0.06). PC20FEV1 and PC40V40p to NKA were significantly lower after thiorphan pretreatment as compared with placebo (mean difference +/- SEM: 2.3 +/- 0.6 and 1.6 +/- 0.5 doubling dose, respectively; p < 0.015).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

C reactive protein in the diagnosis of acute appendicitis.

OBJECTIVE: To find out if the C reactive protein concentration is of any value in the diagnosis of acute appendicitis, either alone or in combination with other laboratory tests. DESIGN: Open study. SETTING: Drechtsteden Hospital, Dordrecht, and Spaarne Hospital, Heemstede, The Netherlands. SUBJECTS: 209 consecutive patients admitted with suspected appendicitis. MAIN OUTCOME MEASURES: Correlation of C reactive protein concentration with age, sex, body temperature, duration of abdominal pain, anorexia, nausea, vomiting, white cell count, neutrophil count, erythrocyte sedimentation rate, and histological appearance of the appendix. RESULTS: 125 patients of the 209 patients had their appendixes removed, and of these 101 had histologically confirmed appendicitis: A C reactive protein concentration of > or = 6 mg/1 alone had a sensitivity of 87% and a specificity of 50%. When the selected variables were subjected to multivariate analysis the most important, in decreasing order, were white blood cell count, female sex, and C reactive protein concentration. Combining the variables was of no additional value. CONCLUSION: measurement of the C reactive protein concentration can increase the accuracy in the diagnosis of acute appendicitis.

Acute Disease↗

PubMed1993

Factors predicting outcome of rheumatoid arthritis: results of a followup study.

OBJECTIVE: To determine prognostic factors in rheumatoid arthritis (RA). METHODS: One hundred thirty-two women with definite RA were followed yearly from an early phase of the disease (symptoms < 5 years) for a mean duration of 6 years. The prognostic value of the first available clinical and laboratory variables and assessments of functional ability was related to several outcome measures (physician's opinion of disease severity, disease activity, radiological abnormalities, functional ability and number of prescribed 2nd-line drugs) by single predictor analysis and by logistic regression. RESULTS: The variables most predictive for one or more of the outcome measures were number of swollen joints, Ritchie score, health assessment questionnaire score, radiographical abnormalities, positive IgM rheumatoid factor (RF), positive IgG-RF, HLA-DR4, and an elevated percentage serum agalactosyl IgG. The accuracy of predicting outcome was calculated from several combinations of these variables, and varied between 70 and 80%. The accuracy based on a combination of the commonly available variables (number of swollen joints, IgM-RF and the erosion score), closely approximated the maximal accuracy that could be achieved. CONCLUSION: The outcome of RA can be predicted by a combination of variables that are commonly available in the clinical setting.

Adult↗

PubMed1993

Exercise 201Tl scintigraphy: evaluation of the additional diagnostic value.

The additional diagnostic yield of exercise 201Tl scintigraphy using both visual and quantitative analysis was determined in 221 patients with known or suspected coronary artery disease (CAD). The coronary arteriogram was adopted as the gold standard. After pretest clinical and exercise electrocardiographic data were taken into consideration, scintigraphy added diagnostic accuracy both in the diagnosis of CAD and of multivessel disease. The diagnostic yield of the scintigraphy in terms of sensitivity and specificity was, however, not significant. In 79% (121/153) of the patients, the diagnosis of the presence, or exclusion, of CAD was highly probable (P > 0.80 or P < 0.20) when considering clinical and exercise data. The diagnosis was, however, not significantly improved by the scintigraphic result. Twenty-seven per cent (20/73) returned a negative scintigraphic results with a high (P > 0.80) prescintigraphic probability for CAD and a positive arteriogram. It was concluded that 201Tl scintigraphy has additional diagnostic value after clinical and exercise parameters were taken into consideration in the diagnosis of coronary artery and multiple vessel disease. It is not recommended to refer patients with either a low or high probability of CAD for screening and diagnosis as in a high proportion of patients the diagnosis of CAD could have been made using clinical or exercise data alone.

Coronary Disease↗

PubMed1993

Which clinical variables contribute to the physician's assessment of medium term outcome in rheumatoid arthritis?

To investigate the clinical variables that contribute to the physician's opinion of the medium term outcome of rheumatoid arthritis (RA), we compared the physician's opinion with statistical modelling of these clinical variables. In 133 young female patients with RA followed yearly (mean followup duration 6 years) from symptom onset, the physician had to state whether the disease course was mild or progressive. Using logistic regression models we concluded that the physician's opinion could be explained by using a compilation of the erosion score, the number of swollen joints, the Ritchie score as measured at the latest visit, in combination with either the mean number of swollen joints during followup, or the number of prescribed second line drugs. Several different models with a common core were equally close to the physician's opinion.

Adult↗

PubMed1993

Outcome of rheumatoid arthritis in relation to age and rheumatoid factor at diagnosis.

Our retrospective followup study reports the outcome of rheumatoid arthritis (RA) in relation to age (under 60 vs 60 years and over) and rheumatoid factor status at diagnosis. A sample of 130 adult patients with RA was assessed at a mean of 5.6 years after diagnosis. At final evaluation disease activity and radiographic damage in seropositive patients were similar in both age groups, but functional capacity was markedly lower in the older onset group, indicating lower functional reserves in this group. In seronegative patients the outcome was favorable in both age groups, especially in the older patients. Seropositive patients in both age groups had more disease activity, a lower functional capacity and more radiographic damage than seronegative patients; these differences were greater in the older onset patients. The mortality in patients with RA compared to the general population (standardized mortality ratio, SMR) was higher in seropositive patients (SMR 2.78, 95% CI 1.70-4.13) but not in seronegative patients (SMR 0.45, 95% CI 0.08-1.13). The relative risk of dying was 6 times higher in seropositive patients than in seronegative patients (95% CI 1.7-20.9).

Aging↗

PubMed1993

Immediate thallium-201 reinjection following stress imaging: a time-saving approach for detection of myocardial viability.

Thallium-201 reinjection following 3-4-hr redistribution imaging improves the detection of viable myocardium but considerably prolongs the total investigation time. We compared the results of immediate 201Tl reinjection with 3-hr redistribution imaging in 120 consecutive patients who were evaluated for myocardial ischemia. Thallium-201 was reinjected immediately following the postexercise study. The images were acquired 1 hr later and reacquired at 3 hr redistribution. A total of 960 segments per imaging series were evaluated, of which 320 (33%) segments showed perfusion defects on the post-exercise images. On the 1-hr images, 220 (69%) segments demonstrated enhanced thallium uptake, 97 (30%) segments did not change and 3 (1%) segments showed reverse redistribution. Of the 100 (97 + 3) persistent defects, only 12 (4%) segments showed fill-in of 201Tl on 3 hr redistribution images. A total of 49 (15%) segments showed reverse redistribution. Defects on postexercise images were seen in 95 patients (79%) of whom 9 (10%) showed no change on immediate reinjection images. In only 1 (1%) patient was the diagnosis changed from myocardial necrosis to myocardial ischemia after analysis of the 3-hr redistribution images. These data indicate that immediate postexercise reinjection of 201Tl followed by 1-hr image acquisition may be superior to 3-hr redistribution imaging in identifying viable myocardium in patients evaluated for myocardial ischemia. This protocol eliminates the need for an additional series of 3-4-hr redistribution images and offers the advantages of reduced total imaging time, improved convenience for the patient and increased patient throughput.

Adult↗

PubMed1992

Long-term effects of a long-acting beta 2-adrenoceptor agonist, salmeterol, on airway hyperresponsiveness in patients with mild asthma.

BACKGROUND: Asthma is characterized by hyperresponsiveness of the airways to bronchoconstrictive stimuli. Long-acting beta 2-adrenoceptor agonists have been introduced as a new therapeutic approach, but there is growing concern about whether control of asthma may deteriorate with the regular use of these agents. We investigated the long-term effects of the beta 2 agonist salmeterol on bronchodilation and on airway hyperresponsiveness to the bronchoconstrictive agent methacholine in mild asthma. METHODS: In a parallel, double-blind study, 24 patients with mild asthma were randomly assigned to treatment with either inhaled salmeterol (50 micrograms, twice daily) (n = 12) or placebo (n = 12) during an eight-week trial. Methacholine challenge was performed before, during, and after the treatment period. Methacholine responsiveness was measured as the provocative concentration (PC20) that caused a 20 percent decrease in the forced expiratory volume in one second (FEV1). RESULTS: There was a significant increase in FEV1 one hour after the inhalation of salmeterol (P = 0.006), which did not differ significantly on days 0, 28, and 56 of the treatment period (increase, 9.8, 9.4, and 8.8 percent of predicted FEV1, respectively; P = 0.91). On the first treatment day, salmeterol afforded significant protection against methacholine-induced bronchoconstriction, as shown by a 10-fold increase in the PC20 as compared with the value at entry (P less than 0.001). After four and eight weeks of treatment, however, the salmeterol-induced change in the PC20 was significantly attenuated (P less than 0.001) to only a twofold increase. Two and four days after treatment ended, the PC20 was not significantly different from the value before treatment (P = 0.15). CONCLUSIONS: Regular treatment of patients with mild asthma with salmeterol leads to tolerance to its protective effects against a bronchoconstrictor stimulus, in this case inhaled methacholine, despite well-maintained bronchodilation. This finding raises concern about the effectiveness of prolonged therapy with long-acting beta 2-adrenoceptor agonists in asthma.

Adrenergic beta-Agonists↗

PubMed1992

The clinical impact of thallium-201 reinjection scintigraphy for detection of myocardial viability.

In a clinical study, the value of thallium-201 reinjection was studied in 139 patients with suspected or known coronary artery disease who showed one or more persistent defects after conventional stress-redistribution imaging. Fifty-nine (42%) patients had sustained a Q-wave myocardial infarction. Sixty-eight (49%) patients showed a reversible defect in at least one myocardial segment at redistribution, while 71 (51%) had persistent defects only. Following reinjection additional segmental filling-in was seen in 95 (68%) patients, including 50 of the 68 (74%) patients with reversible defects and 45 of the 71 (63%) with persistent defects only. On the immediately post-exercise images, 458 (47%) of 973 segments showed perfusion defects. At redistribution 105 (23%) of the 458 defects showed filling-in, whereas of the remaining 353 persistent defects 164 (46%) resolved additionally after reinjection. Thirteen (10%) of 133 Q-wave related defects showed filling-in at redistribution compared with 22 (27%) of 82 remote defects (P = 0.001). After reinjection additional filling-in of defects was seen in 47 (39%) of 120 Q-wave related defects compared with 35 (58%) or 60 remote defects (P = 0.015). Overall, 60 (45%) of 133 Q-wave related defects resolved compared with 57 (70%) of 82 remote defects (P = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗

PubMed1992

Statistical analysis of longitudinal quality of life data with missing measurements.

The statistical analysis of longitudinal quality of life data in the presence of missing data is discussed. In cancer trials missing data are generated due to the fact that patients die, drop out, or are censored. These missing data are problematic in the monitoring of the quality of life during the trial. However, by means of assuming that the cause of the missing data lies in the observed history of the patients and not in their unobserved future, the missing data are ignorable. Consequently, all available data can be used to estimate quality of life change patterns with time. The computations that are required are illustrated with real quality of life data and three commonly used computer packages for statistical analysis.

Analysis of Variance↗

PubMed1992

Combined assessment of technetium-99m SESTAMIBI planar myocardial perfusion images at rest and during exercise with rest/exercise left ventricular wall motion studies evaluated from gated myocardial perfusion studies.

The favorable physical characteristics of technetium-99m-labeled 2-methoxy-2-methylisopropyl-1-isonitril (Tc-SESTAMIBI) enable the combined evaluation of both myocardial perfusion and left ventricular wall motion. To assess the potential of rest and exercise regional myocardial function as an adjunct to planar myocardial perfusion imaging, 60 patients with coronary artery disease and documented arteriographic findings were studied with both protocols during a single study. Exact segmental concordance between myocardial perfusion and wall motion studies was 77% (701/900 segments). Overall sensitivity and specificity to detect hemodynamically significant coronary artery disease with Tc-SESTAMIBI myocardial perfusion imaging were 89% and 79%, respectively, with resting wall motion studies 83% and 71%, respectively, and with rest/exercise wall motion studies, 85% and 71%, respectively. If the results of both perfusion and rest/exercise studies were combined, sensitivity increased to 96% and specificity decreased to 64%. The differences with perfusion studies alone were not statistically significant. Thus despite a good correlation between regional left ventricular function and perfusion, no statistically significant incremental diagnostic value was found when the results of both perfusion and wall motion studies were combined.

Adult↗

PubMed1992

Background EEG reactivity in auditory event-related potentials.

Mental activity has influences on auditory event-related potentials (AERP) as well as on some EEG rhythms, notably the alpha rhythm. In this study, background reactivity (BR) of the EEG was investigated in the context of AERPs. Single responses of 14 healthy subjects were analysed in 3 reaction time AERP experiments of increasing difficulty: the first involved one type of tone delivered at random intervals, the second offered two types of tone (an "oddball" design), and the third offered 3 types of tone. Averages were formed and subtracted from the separate responses to reduce their contribution to the EEG. The 1526 msec EEG epoch was divided in 9 overlapping periods, and averaged power spectra were calculated for these periods. Changes in area of the delta, theta, alpha and beta bands in the course of the epoch were calculated. Background alpha and beta activity decreased following infrequent but not following frequent tones. The decrease was larger for more difficult tasks and reached a maximum in the period in which the AERP P3 and N3 peaks fell. Delta and theta powers showed increases rather than decreases; these could be attributed to the contribution of AERP activity to total EEG power. No clear relationships were found between the amount of background reactivity and peak latencies or reaction times. The occurrence of background reactivity, not apparent in an average, shows that the averaged AERP reveals only part of the EEG changes related to mental activity. Background reactivity proved to be more sensitive to task difficulty than P300 latency. The results are discussed in the context of the additive model of evoked potentials.

Acoustic Stimulation↗

PubMed1992

What is the validity of an "abnormal" evoked or event-related potential in MS? Auditory and visual evoked and event-related potentials in multiple sclerosis patients and normal subjects.

The predictive validity of evoked potentials (EPs) and event-related potentials (ERPs) in multiple sclerosis (MS) has not yet been fully investigated, as only the sensitivity of these tests has sofar been reported. EPs (short, middle and long latency auditory evoked potentials and visual evoked potentials) and ERPs (visual and auditory) were studied in 19 controls and 30 multiple sclerosis (MS) patients. Abnormality thresholds of peak latencies were defined on the basis of the mean plus 2 or 3 standard deviations, based on data from the control group. The effects of changing the latency thresholds and including the absence of peaks in the abnormality definition were assessed. In accordance with earlier reports we found a high sensitivity (up to 93% for bimodal combined EPs and 47% for combined ERPs). False positive rates of separate peaks were low and conformed to expectation. However, combining separate peak measurements increased false positive rates of EPs and ERPs to unacceptably high levels (up to 58% for combined EPs and 32% for combined ERPs). Positive likelihood ratios for bimodal EPs were low (between 1.6 and 4.0, depending on the abnormality definition). They ranged from 1.4 to 2.2 for bimodal ERPs. Abnormal combined EPs or ERPs were therefore not the reliable indicators of functional damage that they are supposed to be. Separate EPs were much more reliable in this respect. ERPs failed to distinguish between the groups, either separately or in combination. Changing the latency threshold and including absent peaks in the abnormality definition influenced the abnormality rates in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Are event-related potentials in multiple sclerosis indicative of cognitive impairment? Evoked and event-related potentials, psychometric testing and response speed: a controlled study.

Bimodal event-related potentials (ERPs), together with evoked potentials (EPs), measures of motor speed (tapping test, EMG latencies and reaction times (RT)), and psychometric test results were studied in a group of 30 multiple sclerosis (MS) patients and 19 controls. ERPs have been advocated as objective tests of cognitive function. In the present study ERPs were compared with the results of psychometric tests, which have a proven validity in measuring aspects of cognitive function that are important in daily life. Abnormal EMG, RT and tapping speed confirmed that motor aspects of performance were slowed in the MS group. In contrast, cognitive non-motor variables such as Raven-IQ and MQ were not significantly abnormal. The proportions of abnormal ERP N2 and P3 latencies did not differ between the groups. It is concluded that the slow performance of MS subjects is therefore most likely not due to cognitive speed decrement, but to motor, executive impairments. No significant relationships between ERP latencies and psychometric test results were found. This held even for a subgroup of 5 MS patients with psychometrically established cognitive impairments. Based on these results, we query the relevance of ERPs as subtle indicators of cognitive impairment in MS.

Cognition Disorders↗

PubMed1992

Are medium and long latency reflexes a screening tool for early Parkinson's disease?

We have studied whether assessment of medium latency (ML) and long latency (LL) reflex amplitudes may serve as a marker for early Parkinson's disease. Twenty-three patients with idiopathic Parkinson's disease (Hoehn and Yahr stage 1 to 4) and 24 controls received 20 4 degrees toe-up rotations of a platform upon which they were standing. All antiparkinsonian medication was withheld for at least 12 h before the study. ML reflexes in the stretched gastrocnemius muscle and LL reflexes in the shortened tibialis anterior muscle were recorded from both legs. ML responses were significantly enhanced in patients compared to controls. In contrast to previous studies which studied patients who continued their usual treatment, we observed that LL responses were significantly reduced in patients compared to controls. For the purpose of individual analysis, we subsequently determined the optimal specificity and sensitivity using various criteria for abnormality. The presence of either enhanced ML responses or reduced LL responses (or both) in at least one leg yielded a maximum sensitivity of 65.2% with a specificity of 75.0% (positive likelihood ratio 2.6; negative likelihood ratio 0.5). Abnormal reflexes were almost exclusively present in patients with advanced and long-standing Parkinson's disease. These results show abnormalities of ML and LL responses in advanced Parkinson's disease, but render it unlikely that these abnormalities are a suitable screening tool for early stages of the disease. The fact that LL responses were reduced in patients taken off antiparkinsonian medication raises the possibility that this reflex is under supraspinal dopaminergic control.

Aged↗

PubMed1992

Upper gastrointestinal complaints and complications in chronic rheumatic patients in comparison with other chronic diseases.

The aim of this study was to compare the frequency of upper gastrointestinal (GI) complaints and complications between chronic rheumatic patients who are most often non-steroidal anti-inflammatory drugs (NSAIDs) users and patients with other chronic conditions. In this comparison we took into account known risk factors for upper GI disease. To achieve the study aims we performed a combined cross-sectional and retrospective study. We therefore interviewed by means of a standard questionnaire, an index and a reference group, about current upper GI complaints and previous complications. The former group comprises 578 outpatients of the Department of Rheumatology, the latter of 531 outpatients of the Departments of Internal Medicine, Pulmonology, and Cardiology. Although the number of patients in the index group being chronically treated with NSAIDs was very high (62% versus 9% in the reference group: P < 0.00001), no between-group differences were found for the frequency of several current upper gastrointestinal complaints or for the number of upper gastrointestinal investigations ever performed (35% and 37%: NS) or for the use of gastric drugs (14% and 10%: NS). Risk factors for upper GI complaints were not related to NSAID use but with the use of prednisolone, history of duodenal ulcer disease, family history of peptic ulcer disease and female sex. For peptic ulcer disease, bleeding, and gastric surgery, the only difference between the index and reference groups concerned the frequency of gastric ulcers (6.7% and 2.8%: P < 0.005), which was highest in patients with rheumatoid arthritis. Upper GI bleeding had more often been present in male seropositive rheumatoid arthritis patients (13.2% [corrected] and 4.5%: P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1992

The course of alcohol amnestic disorder: a three-year follow-up study of clinical signs and social disabilities.

Forty-four patients with alcohol amnestic disorder were prospectively studied from 1987 to 1990. The cognitive impairment, social disability and mental symptoms of patients under different conditions were compared. Thirty-three patients (75%) had no symptoms of Wernicke's disease nor a medical history to suggest its existence. The course of mean cognitive impairment of patients in different settings was stable. Change in intelligence quotient correlated with alcohol consumption during the study. The development of social disability differed remarkably in different settings. Patients in a large nursing home deteriorated and patients in small-scale sheltered accommodation improved.

Activities of Daily Living↗