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Biomedical subjects

M Hietanen

Publications and source records attributed to M Hietanen.

At least 37 records · Page 2Linked to original sources
PubMed1999

Suppression of mismatch negativity by backward masking predicts impaired working-memory performance in alcoholics.

BACKGROUND: Pronounced disruption of memory traces by subsequent distractors may result in impaired behavioral memory performance in alcoholics. METHODS: This hypothesis was investigated with an electrophysiological index of auditory sensory-memory traces, mismatch negativity, a preattentive event-related potential component elicited by a "deviant" tone within a train of "standard" tones. RESULTS: Inserting a masking stimulus after these tones abolished mismatch negativity in alcoholics (DSM-IV) but not in social-drinker controls. This effect predicted working-memory impairment in alcoholics, and correlated significantly with self-reported alcohol consumption of the subjects. Furthermore, the backward-masking mismatch negativity paradigm detected sensory-memory impairment in 9 of 20 alcoholics (sensitivity 45%), whereas all 20 social drinkers were unimpaired (specificity 100%). CONCLUSIONS: Vulnerability to memory trace disruption by shortly following sounds may be one of the factors contributing to behavioral memory dysfunction in alcoholics. The present result may provide an objective neurophysiological tool for investigation of alcohol-induced and other degenerative brain disorders.

Adult↗
PubMed1998

Clinical determinants of poststroke dementia.

BACKGROUND AND PURPOSE: Frequency of poststroke dementia is high, and stroke considerably increases the risk of dementia. The risk factors for dementia related to stroke are still incompletely understood. We sought to examine clinical determinants of poststroke dementia in a large well-defined stroke cohort. METHODS: The study group comprised 337 of 486 consecutive patients aged 55 to 85 years who 3 months after ischemic stroke completed a comprehensive neuropsychological test battery and MRI, including structured medical, neurological, and laboratory evaluations; clinical mental status examination; interview of a knowledgeable informant; detailed history of risk factors; and evaluation of stroke type, localization, and syndrome. The DSM-III definition for dementia was used. RESULTS: Frequency of any poststroke dementia was 31.8% (107/337), that of stroke-related dementia (mixed Alzheimer's disease plus vascular dementia excluded) was 28.4% (87/306), and that of dementia after first-ever stroke was 28.9% (79/273). The patients with poststroke dementia were older and more often had a low level of education, history of prior cerebrovascular disease and stroke, left hemispheric stroke (reflecting laterality), major dominant stroke syndrome (reflecting laterality and size), dysphasia, gait impairment, and urinary incontinence. The demented patients were also more frequently current smokers, had lower arterial blood pressure values, and more frequently had an orthostatic reaction compared with the nondemented stroke patients. The correlates of dementia in logistic regression analysis were dysphasia (odds ratio [OR], 5.6), major dominant stroke syndrome (OR, 5.0), history of prior cerebrovascular disease (OR, 2.0), and low educational level (OR, 1.1). When we excluded those with cerebrovascular disease plus Alzheimer's disease or those with recurrent stroke, the order of correlates remained the same. When the patients with dysphasia (n=30) were excluded, the correlates were major dominant syndrome (OR, 4.6) and low educational level (OR, 1.1). CONCLUSIONS: Our data suggest that a single explanation for poststroke dementia is not adequate; rather, multiple factors including stroke features (dysphasia, major dominant stroke syndrome), host characteristics (educational level), and prior cerebrovascular disease each independently contribute to the risk.

Age Factors↗
PubMed1998

Neuropsychological correlates of duration of glances at secondary tasks while driving.

The aim of this study was to find out the neuropsychological measures correlating with overlong glances at secondary in-car tasks while driving. Fifteen. patients with brain damage (without clear neurological or neuropsychological restriction on driving a car) and 11 healthy participants drove a route of 126 km and performed a series of secondary tasks while driving on a highway in an instrumented compact car. Four videocameras allowed detailed analysis of glances during in-car tasks. Neuropsychological measures focused on executive functions, memory, visuospatial skills, and fine motor skills. Moreover, patients' emotional self-evaluation and relatives' evaluation of patients' competencies were included. The proportion of overlong glances away from the road during in-car tasks was greater among the patients than. the healthy drivers. The long glances of the patients correlated strongly with motor and visuospatial deficits, cognitive inflexibility, emotional symptoms, and relatives' evaluations of patients' impaired sensomotor abilities. The results suggest that the frequency of overlong glances was increased by 2 factors: (a) impaired motor and visuospatial skills that evidently caused difficulties in the manipulation of the equipment of the secondary tasks, and (b) impairments of executive functions that were likely to decrease the ability to control the risks related to long glances at the in-car tasks. The slowing of speed during secondary tasks was on the average rather slight and not significantly more pronounced among patients than control drivers, indicating that patients failed to reduce their speed and thus the risk related to prolonged glances at in-car tasks.

Journal Article↗
PubMed1995

Magnetic fields of video display terminals and pregnancy outcome.

The magnetic fields emitted by video display terminals (VDTs) and their potential association with pregnancy outcome are discussed. The majority of the epidemiologic studies suggest that VDT work is not related to adverse pregnancy outcome. The exposure to magnetic fields from modern VDTs is usually even lower than that from other sources in the office environment, such as printers and photocopying machines. There are, however, some indications of an increased risk of adverse pregnancy outcome among women exposed to high levels of extremely low-frequency magnetic fields of VDTs or electric appliances at home. Because the present evidence is not sufficient to allow the drawing of final conclusions, it would be important to examine the effects of exposure to higher fields existing at industrial work places.

Computer Terminals↗
PubMed1994

Psychomotor capacity and occurrence of wrist tenosynovitis.

A case-referent study was carried out among meatcutters, sausage markers, and packers in a large meat-processing plant to investigate the association between psychomotor capacity and occurrence of tenosynovitis. Reaction time, movement time, manual dexterity, visual attention and visuospatial ability were measured in 26 cases with a history of two or more episodes of tenosynovitis and 26 referents of similar gender, occupation, age, and job seniority with no episodes of the disease. No differences were found between the cases and the referents in any of the tests of psychomotor capacity. The results suggest that psychomotor capacity, as measured with the tests of this study, is a poor predictor of wrist tenosynovitis.

Adult↗
PubMed1992

Magnetic fields of video display terminals and spontaneous abortion.

The aim of this study was to examine whether work with a video display terminal and exposure to the magnetic fields of video display terminals are related to spontaneous abortion. The study was conducted among women employed as bank clerks and clerical workers in three companies in Finland. The cases (191 spontaneous abortions) and controls (394 births) were identified from Finnish medical registers for the years 1975-1985. Use of video display terminals was defined using the workers' own reports and information provided by the companies. The assessment of exposure to the magnetic fields was based on measurements of the fields of video display terminals. The odds ratio for spontaneous abortion for working with video display terminals was not increased (odds ratio = 1.1, 95% confidence interval 0.7-1.6). However, the odds ratio for workers who had used a video display terminal with a high level of extremely low frequency magnetic fields (> 0.9 microT) was 3.4 (95% confidence interval 1.4-8.6) compared with workers using a terminal with a low level of these magnetic fields (< 0.4 microT). Adjustment for ergonomic factors and mental work load factors changed the odds ratio for magnetic field exposure only very slightly. The findings suggest the need for future studies with assessment of exposure to the magnetic fields in the actual working environment to confirm the possible risk.

Abortion, Spontaneous↗
PubMed1992

Evaluation of hazards in CO2 laser welding and related processes.

High-power CO2 lasers are used extensively in various industrial applications. In most cases they form part of open-beam equipment and have a power of several kilowatts, and are thus designated as Safety Class 4 systems. In addition to the invisible i.r. laser beam (10.6 microns), u.v. radiation and visible light may be emitted. In the present work a power meter controlled by microprocessor and a spectroradiometer measured the scattered or reflected laser radiation. In addition, concentration levels of welding and cutting fumes and of pyrolysis products of plastics were determined during various laser processes. Finally, a safety analysis was performed to compare the hazards of laser welding with those of conventional welding methods: this showed that the use of laser systems can eliminate many traditional risks, but the worker must be protected not only against the coherent laser beam, but also from incoherent blue light and u.v. radiation.

Air Pollutants, Occupational↗
PubMed1991

Ocular exposure to solar ultraviolet and visible radiation at high latitudes.

Exposure of the eyes to ultraviolet (UV) radiation and short wavelength light, blue light, from the sun was assessed under realistic geometric conditions. A spectroradiometer with a double monochromator was used to determine the spectral irradiance at 1-nm intervals within the wavelength range of 250-800 nm. Biological weighting functions were used to calculate the blue-light radiance and the weighted UV irradiance. In addition, a photometer with a 1 degree angle of view was used to measure the ambient luminance. The results indicate that sizable amounts of UV radiation and blue light can be reflected from different environmental surroundings. Hence various groups of outdoor workers seem to be at risk of chronic ocular overexposure to solar radiation. When occupational exposure limits for UV and visible radiation are revised, the risks of chronic exposure should receive more consideration than to date.

Altitude↗
PubMed1990

Immunohistochemical evidence for the presence of protein kinase C beta-subtype in rat motoneurons and myoneural junctions.

The localization of protein kinase C beta-subtype-like immunoreactivity (PKC-beta-LI) was studied in the spinal cord and in different striated muscles of rat. In the spinal cord, large motoneurons in the ventral horn were PKC-beta-immunoreactive (IR). Strong immunoreactivity to PKC-beta was found in large nerve bundles between muscles, and in smaller nerves among muscle fibers. Myoneural junctions, which showed weaker immunoreactivity to PKC-beta, were also demonstrated in all muscles studied; the external ocular muscles, the diaphragma and the triceps surae muscle. Muscle cells were not labelled.

Animals↗
PubMed1990

Immunocytochemical study of the relations of acetylcholinesterase, enkephalin-, substance P-, choline acetyltransferase- and calcitonin gene-related peptide-immunoreactive structures in the ventral horn of rat spinal cord.

Calcitonin gene-related peptide (CGRP)-like immunoreactivity was localized immunocytochemically in the large motoneurons in the ventral horn of rat spinal cord. Using fluorescence double-labelling substance P (SP)-immunoreactive nerve fibres were found to surround both the CGRP-positive and negative motoneurons, whereas enkephalin (ENK)-immunoreactive fibres surrounded mainly CGRP-negative cells. All CGRP-like immunoreactive motoneurons were also choline acetyltransferase (ChAT)- and acetylcholinesterase (AChE)-positive. On the other hand a large population of ChAT- and AChE-positive motoneurons were devoid of CGRP-immunoreactivity. It is probable that CGRP/ChAT/AChE-positive cells surrounded by SP-positive fibres have different functions in motoric nervous system than the CGRP-negative ChAT/AChE-positive cells, which are surrounded by ENK-immunoreactive fibres.

Acetylcholinesterase↗
PubMed1988

Dementia and treatment with L-dopa in Parkinson's disease.

We compared the neuropsychological performance of patients with Parkinson's disease who were young at onset of the disease (mean age, 41.4 years) and had received prolonged L-dopa treatment (mean, 52.1 months) with nontreated patients of the same age. A similar comparison was made for patients who were older at onset of the disease (mean, 62.1 years). There were no significant differences in cognitive and memory functions between the L-Dopa-treated and untreated young patients, whereas the L-Dopa-treated patients in the older age group performed more poorly than untreated patients in some memory tests (Wechsler Memory Scale I: logical and visual) and cognitive functions (Wechsler Adult Intelligence Scale: similarities, block design, and cognitive flexibility). Treatment duration, disease duration, and mean L-Dopa dose were comparable for the two age groups. After linear effects of age and disease duration had been eliminated, the duration of L-Dopa treatment did not correlate with the cognitive variables studied. These observations suggest that treatment with L-Dopa may not be the cause of cognitive impairment in Parkinson's disease.

Adult↗
PubMed1988

The effect of age of disease onset on neuropsychological performance in Parkinson's disease.

One hundred and eight noninstitutionalized patients with Parkinson's disease were studied to find out whether the age of disease onset affects patients' cognitive, memory and psychomotor performance. "Early onset" patients (whose disease began before 60 years of age) showed a wide spectrum of impairments in neuropsychological performance compared with age-matched normal subjects. However, only one (2%) of these patients was demented according to DSM III criteria. Dementia was more frequent in patients with equivalent disease duration, but with late onset of disease (over 60 years); 13 of such patients (25%) were demented. The present study supports previous findings which show that dementia increases with advancing age in Parkinson's disease. It also suggests that cognitive changes are also found in patients with early onset of disease.

Adult↗
PubMed1986

The age of onset of Parkinson's disease: etiological implications.

We have conducted a hospital-based survey of the age-specific prevalence of Parkinson's disease in 551 patients from Helsinki and Vancouver. We conclude that the disorder may be starting earlier than previously and we discuss the implications of this finding for the etiology of Parkinson's disease.

Adult↗
PubMed1986

Dementia in movement disorders.

Of all the movement disorders, Huntington's disease has been most consistently associated with dementia, while it is only over the last decade that intellectual cognitive decline have been recognized as common features of Parkinson's disease. It is now known that the pathology in these two conditions reflects differential involvement of the striatum. The Huntington lesion is primarily in the caudate, while the Parkinson lesion preferentially affects the putamen. Both conditions have more diffuse pathology, and dementia may also occur in a wide range of other extrapyramidal diseases, such as progressive supranuclear palsy, the parkinsonism-dementia complex of Guam, and certain spinocerebellar degenerations. Clinicopathological correlations will be reviewed in these disorders of primarily subcortical pathology, and comparisons will be made with Alzheimer's disease, a disorder of predominantly cortical pathology.

Alzheimer Disease↗
PubMed1986

Cognitive performance in early Parkinson's disease.

The cognitive, memory and psychomotor performance of 67 patients with Parkinson's disease who had not received any antiparkinson medication was compared with the performance of 43 healthy subjects matched by age and education. The principal impairments in the patients were motor ones, evident in various tests such as general motor slowness and delayed initiation of movement, and they correlated with clinical rigidity and hypokinesia but not with tremor. The performance of the patients was inferior to that of the controls in memory tests involving the processing of information and learning (logical memory, associative learning) but not in less demanding tasks such as the retrieval of numbers. The total disability was due to a combined effect of aging and disease. A decrease of about 15% in the psychomotor and cognitive performance, related to aging alone, can be expected to occur between the ages of 50 and 70. The performance of the patients in memory tests and other tests evaluating cognitive capacity did not correlate either with their motor disability or with their mood. A possibility therefore exists that biological processes behind the cognitive decline and the motor disability are separate, even if they may occur simultaneously.

Adult↗
PubMed1985

Initial treatment of parkinsonism with 8-alpha-amino-ergoline.

We treated 12 patients with Parkinson's disease with an 8-alpha-amino-ergoline derivative, CU 32-085. The daily dosage was increased slowly to 7 mg over 9 weeks, held constant for 8 weeks, then replaced by placebo for 4 weeks. We found statistically significant benefit over placebo or pretreatment disability. The effect was seen at daily dosages of 3 mg or more. Its magnitude was dose related. There was no further improvement on prolonged treatment with 7 mg daily. Side effects were mild and did not require interruption of treatment.

Adult↗