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Biomedical subjects

M Hofman

Publications and source records attributed to M Hofman.

17 recordsLinked to original sources
PubMed2003

Can the Expanded Disability Status Scale be assessed by telephone?

Information from patients who are unable to continue their visits to a study centre may be of major importance for the interpretation of results in multiple sclerosis (MS) clinical trials. To validate a questionnaire based on the Expanded Disability Status Scale (EDSS), patients in five different European centres were assessed independently by pairs of trained EDSS raters, first by telephone interview and a few days later by standardized neurological examination. Seventy women and 40 men with an average age of 43.7 years (range 19-74 years) were included in the study. Mean EDSS score at the last visit was 4.5 (0-9). EDSS assessment by telephone was highly correlated with the EDSS determined by physical examination (Pearson's correlation coefficient = 0.95). An intraclass correlation coefficient (ICC) of 94.8% was found for the total sample; 77.6% and 86%, respectively, for patients with EDSS < 4.5 (n = 46) and > 4.5 (n = 64). Kappa values for full agreement were 0.48; for variation by +0.5 steps and +1.0 steps, 0.79 and 0.90, respectively. Best agreement could be found in higher EDSS scores, where assessment by telephone interview might be needed most. The telephone questionnaire is a valid tool to assess EDSS score in cases where the patient is unable to continue visiting a study centre or in long-term follow-up of trial participants.

Adult↗
PubMed2002

Binaural weighting of pinna cues in human sound localization.

Human sound localization relies on binaural difference cues for sound-source azimuth and pinna-related spectral shape cues for sound elevation. Although the interaural timing and level difference cues are weighted to produce a percept of sound azimuth, much less is known about binaural mechanisms underlying elevation perception. This problem is particularly interesting for the frontal hemifield, where binaural inputs are of comparable strength. In this paper, localization experiments are described in which hearing for each ear was either normal, or spectrally disrupted by a mold fitted to the external ear. Head-fixed saccadic eye movements were used as a rapid and accurate indicator of perceived sound direction in azimuth and elevation. In the control condition (both ears free) azimuth and elevation components of saccadic responses were well described by a linear regression line for the entire measured range. For unilateral mold conditions, the azimuth response components did not differ from controls. The influence of the mold on elevation responses was largest on the ipsilateral side, and declined systematically with azimuth towards the side of the free ear. Near the midsagittal plane the elevation responses were clearly affected by the mold, suggesting a systematic binaural interaction in the neural computation of perceived elevation that straddles the midline. A quantitative comparison of responses from the unilateral mold, the bilateral mold and control condition provided evidence that the fusion process can be described by binaural weighted averaging. Two different conceptual schemes are discussed that could underlie the observed responses.

Acoustic Stimulation↗
PubMed2000

Alzheimer's disease, depression and normal ageing: merit of simple psychomotor and visuospatial tasks.

INTRODUCTION: A brief psychometric test battery was used to differentiate Alzheimer's disease (AD) patients from patients with depression and healthy age-matched control subjects. The purpose was to investigate the discriminative value of simple psychomotor and visuospatial tasks that were implemented in a computer-assisted test battery. METHODS: Manumotoric coordination, discrimination reaction time and performance on a visuospatial pattern-matching task were assessed. Subjects were 30 patients with the diagnosis of probable AD (mild to moderate), 22 patients with a major depression and 15 healthy normal control subjects. RESULTS: Discrimination reaction time separated the three groups most distinctly, but general level of cognitive functioning was a significantly confounding variable. There were no differences between the AD and the depressed patients when the MMSE was used as a covariate. Substantial deficiencies in manumotoric coordination were found in both demented and depressed patients. The visual pattern-matching task yielded longer reaction times in both patient groups than in the control group. CONCLUSION: Translated into neuropsychological terms, these data suggest deficiencies in basic central operations, a slowing of central information processing and attentional deficits in AD and depressed patients. Psychomotor tasks were able to distinguish effectively healthy elderly persons from AD and depressed patients. This test battery, however, appears to be limited in differentiating AD from depression.

Aged↗
PubMed2000

Multicenter case series of pediatric metformin ingestion.

OBJECTIVE: There are no large studies, case series, or case reports of metformin ingestion in children. This study summarizes the clinical course and outcomes of metformin ingestion in children reported to the American Association of Poison Control Centers-certified regional poison centers. METHODS: This was a case series of all metformin ingestions in patients <18 years of age reported to eight regional poison centers. Data collection included age, gender, dose ingested, co-ingestants, symptoms, vital signs, laboratory values, length of hospital stay, and medical outcome. Entrance into the study required at least 24 hours of follow-up. RESULTS: Fifty-five cases were collected. Ages ranged from 15 months to 17 years, with a mean (+/- SD) of 42+/-4.4 years. The dose ingested, by history, ranged from 250 mg to 16.5 g, with a mean and median of 1710+/-3391 and 500 mg, respectively. Forty-one children (76%) ingested a maximum of two tablets (< or =1700 mg). In the children younger than six years, dosage ranged from 9 to 196 mg/kg, with a mean and median of 60+/-41.1 and 40 mg/kg, respectively. Thirty-seven children were evaluated in a healthcare facility. Clinical effects were limited to nausea (2), diarrhea (2), and dizziness (1). None of the 38 children who had serial glucose measurements experienced hypoglycemia. Arterial blood gas and electrolyte measurements were performed in three and 19 children, respectively. No evidence of acidosis was demonstrated. Two children had lactate concentrations measured and were determined to be in the normal range. Twenty-nine patients received activated charcoal. Five patients received parenteral glucose and one adolescent with a history of diabetes received insulin for hyperglycemia. CONCLUSIONS: Unintentional ingestion of < or =1700 mg of metformin in the healthy pediatric population does not appear to pose a significant health risk of hypoglycemia or detrimental outcome. In the 21 children who were tested for either blood glucose, electrolyte, or lactate concentrations, no evidence of lactic acidosis was seen.

Acidosis, Lactic↗
PubMed1993

The role of magnetic resonance in the evaluation of functional results after CABG/PTCA.

Magnetic resonance imaging (MRI) is a non-invasive modality which can be used for direct visualization of coronary artery bypass grafts. Spin-echo and gradient-echo (cine-MRI) techniques are now available on standard MR machines and provide information on graft morphology and graft patency with a 90% accuracy. By combining the standard techniques with MR phase velocity mapping, the flow rate in the graft can be measured, thereby offering a unique non-invasive assessment of the graft function. Newer techniques include MR coronary angiography, pharmacologically induced stress MRI, ultrafast MRI of the first-pass (perfusion) of a paramagnetic contrast agent through the myocardium, and 31P MR spectroscopy of high-energy phosphate metabolism of the myocardium. All of these may develop into valuable diagnostic tools for the assessment of functional results after CABG or PTCA, but still require clinical validation. At present, MRI is a useful screening procedure for assessment of graft patency and function in post-operative pain syndromes and in late graft occlusion or stenosis.

Angioplasty, Balloon, Coronary↗
PubMed1990

[The issue of lower limb amputations in vascular diseases].

A series of 363 amputations in 335 patients treated between 1979 and 1988 because of chronic peripheral vascular disease was reviewed. In years from 1979 to 1988 3500 vascular surgical procedures were carried out. In 217 cases (6,2%) subsequent amputation was necessary. Previously, from 1962 to 1978 it had occurred in 8,5%. The authors experience is indicative of limb vascularization as decisive factor in choosing the level of amputation. In high aortoiliac arterial occlusion a vascular procedure is carried out, resulting in good blood supply of the stump allowing lowering the level of amputation and shortening recovery period.

Adult↗
PubMed1986

Systems management: strategies to increase effectiveness.

As healthcare organizations evolve into more competitive, complex, business structures, they must increasingly rely on information systems to tie together disparate divisions into a cohesive whole. If information systems are to effectively assist in this goal, they must be managed by professionals that have the power and the ability to accomplish the job.

Computers↗
PubMed1985

Fluorescence depolarization assay for quantifying alpha-amylase in serum and urine.

We have developed a new method for quantifying alpha-amylase (EC 3.2.1.1) in serum and urine by fluorescence depolarization. Amylase in the sample catalyzes the hydrolysis of the substrate, a fluorescein-labeled amylose. This results in decreased fluorescence polarization, owing to the increased rate of rotation of the amylose fragment relative to the intact substrate. The TDx amylase assay is calibrated with six human-serum-based pancreatic amylase calibrators. Amylase activities are determined by interpolation from the calibration curve, which is stored in the TDx analyzer's memory. Results correlate well with those by the Du Pont aca assay and the Beckman "DRI-STAT" assay. Endogenous glucose does not interfere. CVs are less than 6%, and the reagents are stable in liquid form.

Fluorescence Polarization↗