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Biomedical subjects

J Risberg

Publications and source records attributed to J Risberg.

At least 73 records · Page 4Linked to original sources
PubMed1986

Regional cerebral blood flow in long-term heavy cannabis use.

Regional cerebral blood flow (rCBF) was measured by the 133Xenon inhalation method in nine male chronic cannabis users. The rCBF level in cannabis users was significantly (11%) lower than that of age- and sex-matched healthy controls. Four of the subjects were reexamined after 9-60 days of detoxification and showed a significant (12%) increase of the CBF level at followup. No significant regional flow abnormalities were noted. The global CBF reduction seen in the early phase of detoxification is most likely the consequence of the dysfunction of the central nervous system accompanying chronic cannabis use.

Adolescent↗
PubMed1986

Behavioral observations during performance of the WAIS Block Design Test related to abnormalities of regional cerebral blood flow in organic dementia.

Twenty-one patients with symptoms of organic dementia were studied concerning the relationship between the behaviour when solving the Wechsler Block Design Test and the localization of cerebral dysfunction as indicated by the regional cerebral blood flow (rCBF). Eleven patients with decreases of rCBF in frontal regions (Group A) were compared with 10 patients with postcentral decreases (Group B). Conventional Block Design scores were about equal in the two groups. Group A patients showed significantly less anxiety and self-criticism, were less systematic and made fewer attempts at completion. Rotations were displayed more often in Group B. The results illustrate the significance of information obtained by behaviour observation in the test situation.

Aged↗
PubMed1986

Hyperbaric exposure to a 5 ATA He-N2-O2 atmosphere affects the cardiac function and organ blood flow distribution in awake trained rats.

Previous studies on rats have demonstrated an increased myocardial blood flow (MBF) in spite of an unchanged cardiac output (CO), mean arterial pressure (MAP), and heart rate (HR) when rats were exposed to a 5 ATA ambient pressure (PN2 = 4.8 ATA, PO2 = 0.2 ATA). We have investigated the changes in CO and organ blood flow by the microsphere method on 9 awake, trained rats exposed to a 5 ATA ambient pressure with surface pressure of N2 (= 0.8 ATA) and O2 (= 0.2 ATA), increasing the ambient pressure with He. The chamber temperature was 30-31 degrees C. CO and organ blood flow were measured in control and after 15 min under pressure. No changes were observed in CO, HR, or MAP during the hyperbaric exposure, indicating unchanged external work of the heart when calculated as MAP X HR. The pulse pressure however increased significantly (P less than 0.05). MBF increased at the same time by 36% (P less than 0.01), equally distributed in the right and left ventricles (P less than 0.01). The fact that myocardial perfusion increases when ambient pressure is elevated, independent of atmospheric inert gas composition, invites the conclusion that this change is due to the ambient pressure itself and not to a specific effect of N2 or He as inert gas at 5 ATA. The blood flow to the adrenals increased by 77% (P less than 0.01), the liver by 105% (P less than 0.05), while the blood flow to the skeletal muscles decreased by 30% (P less than 0.05). The blood flow to the lungs, the paws, and the outer ear increased, most likely due to the high ambient temperature in the chamber. We may conclude that HR does not change in a normoxic hyperbaric atmosphere. High ambient pressure increases the pulse pressure, but the MAP and CO remain unchanged. These changes and the changes in organ blood flow need well-balanced neuronal or hormonal reflexes to distribute an unchanged CO under pressure. The exact explanation is not known.

Animals↗
PubMed1985

Changes in cerebral blood flow after stereotactic thalamotomy.

Regional cerebral blood flow (rCBF), a parameter of neuronal activity in the brain, was measured by the 133Xe inhalation method in 43 patients undergoing stereotactic thalamotomy. A postoperative flow reduction of about 2% in the operated hemisphere was found, persisting in further measurements performed after a year. There was no consistent change in the pattern of regional flow distribution. The results indicate a diminished level of activity in the hemisphere subjected to thalamotomy, but the change could not be linked to any specific area or function.

Adult↗
PubMed1985

Effects of long-term exposure to solvents in the paint industry. A cross-sectional epidemiologic study with clinical and laboratory methods.

The effects of organic solvents on 50 male workers exposed 5-46 (mean 18) years were studied with a cross-sectional design. Referents were matched pairwise according to age and education. An analysis of confounders confirmed good comparability between the two groups. As indicators of organic brain dysfunction regional cerebral blood flow was measured and the power spectrum of the subjects' electroencephalograms was analyzed, the former being reduced 4% and the latter showing increased power in the delta and beta bands in the exposed group. Symptoms of brain dysfunction were significantly more frequent among the exposed subjects and showed an exposure-effect relationship. Neuropsychological tests revealed definite indication of brain dysfunction in 14% of the exposed subjects in comparison to none in the reference group. The exposed subjects performed significantly worse than the referents in tests measuring focused attention abilities. A neurophysiological examination of the peripheral nervous system showed no difference between the groups. Clinical chemistry demonstrated no differences that could be explained by solvent exposure.

Adult↗
PubMed1984

The effects of bromvincamine and vincamine on regional cerebral blood flow and mental functions in patients with multi-infarct dementia.

The effects of vincamine and bromvincamine (BV 26-723) on mental functions and regional cerebral blood flow (rCBF) measured by the 133Xe inhalation method, were investigated in ten patients with mild to severe symptoms of multi-infarct dementia. The double blind cross over design included three treatment periods, each of 2 weeks' duration. The patients were drug free at the time of the first investigation in each treatment period. Then placebo, vincamine or bromvincamine was given orally (4 X 20 mg/day). Psychiatric evaluation, psychometric assessment and measurement of rCBF were done at start of medication and after 1 and 2 weeks during medication. There were 2 drug-free weeks between the first and second, and second and third treatment periods. Results from treatment with vincamine showed a significant increase in the global CBF level and reduction of initial right-left asymmetry of hemispheric means. No effects were seen in regional flow patterns. Performance score on a verbal memory test increased significantly. No significant effect on the global rCBF level was indicated for bromvincamine. However, the number of ischemic regions decreased significantly during treatment. Performance on two memory tests improved significantly. No significant changes in overall psychiatric ratings were observed for any of the treatment periods.

Aged↗
PubMed1983

Effects on the regional cerebral blood flow of long-term exposure to organic solvents.

Regional cerebral blood flow (rCBF, 133Xe inhalation method) was measured in 50 male paint-factory workers with a mean of 18 years of exposure to a mixture of organic solvents. A group of 50 workers in a sugar-refinery, matched for age and education, served as controls. The measurements were made during resting and during activation by mental tasks (4%; P less than 0.05) in the exposed group. Largest differences were seen in frontotemporal areas. The difference between the exposed group and and controls increased at higher dose levels. The largest rCBF-increases during mental activation were seen in the exposed group, especially in the highest exposed subjects. This finding might indicate mechanisms compensating for a somewhat defective brain function. Although the differences between the groups were generally small with considerable overlap, the results give some evidence of disturbances of brain blood flow and brain function likely related to the influence of organic solvents.

Adult↗
PubMed1983

Cortical processing of visual and tactile stimuli studied by non-invasive rCBF measurements.

Blood flow determinations were made in 32 cortical regions of normal subjects during processing of visual and tactile stimuli. One experiment involved eight subjects who were studied during three conditions of visual stimulation achieved by a Spiral-After-Effect (SAE) apparatus: 1. looking at a stationary spiral, 2. a rotating spiral, and 3. performing the SAE test. Average cortical flow increases during these conditions compared to resting were 5%, 7% and 12% respectively. Local activation was seen in occipital, parietal, temporal, and frontal regions. The magnitude and spread of local flow increases were related to task complexity. In another experiment ten subjects were studied during rest and tactile stimulation of the right hand, left hand, and both. The subjects were instructed either to ignore the stimulation (sensation) or to pay attention to it. Sensation was accompanied by parietal and prefrontal flow increases contralateral to side of stimulation. Attention to the right hand mainly enhanced right hemisphere flow, in the same areas as during sensation. Attention to the left hand was associated with large, diffuse flow increases in both hemispheres. The results support recent proposals of right hemisphere dominance for functions related to attention.

Adult↗
PubMed1982

Regional cerebral blood flow and verbal memory after chronic exposure to organic solvents.

Regional cerebral blood flow (rCBF; 133Xe-inhalation method) was investigated in 32 industrial workers (age: 51 +/- 9 years) who had been exposed to organic solvents during an average of 24.5 years. The measurements were made at rest and during learning of associated word pairs. The resting flow level was 17% lower than expected for normal subjects of similar age and the activation-induced changes of rCBF during the test lacked the frontal activation normally seen. Significant correlations between age, length of exposure, and rCBF level were found. In order to control for the age factor, results were also calculated from two subgroups of similar age but with very different levels of exposure (13 and 31 years of average exposure). The two groups differed only slightly in resting rCBF. A marked difference was, however, seen during activation, with significant post-central flow increases recorded in the lower-exposed group only. The results indicate the potential of the rCBF method for elucidating functional cortical changes related to neurotoxic effects of organic solvents.

Aging↗
PubMed1981

Regional cerebral blood flow during alcohol withdrawal.

Serial bilateral measurements of regional cerebral blood flow (rCBF) by the xenon Xe 133 inhalation method were made during 13 withdrawal periods in 12 male alcoholics with pronounced physical dependence. A significant global reduction of rCBF was found during the first two days of withdrawal. The largest decreases were seen in cases with clouded sensorium and with an extended preceding drinking period. An rCBF distribution with relatively high temporal and low parietal flows during the first two days was coupled to aggravated symptoms. In two men who reported auditory and visual hallucinations during the measurements, elevated rCBF values were found in the temporal, Sylvian, and occipital regions.

Alcohol Withdrawal Delirium↗
PubMed1981

rCBF measurements by 133Xe inhalation: recent methodological advances.

Some recent methodological improvements of the 133Xe-inhalation method for determination of the rCBF are reviewed. Improvements of the classical (Obrist) method of analysis involving routines for correction of background, remaining activity and contamination from 133Xe in the air passages are described. Advantages and limitations of the ISI as compared to the bi-exponential flow parameters are discussed as well as different ways to determine technical quality and reliability of the flow calculations. Finally, a new method of curve analysis based on Fourier transforms is described. This method allows use of the full curve from start of 133Xe breathing and offers improved methods for correction of influence from air passages and arteries. Its advantages in terms of greater sensitivity and validity are discussed.

Cerebrovascular Circulation↗
PubMed1981

rCBF measurements by 133Xe inhalation: applications in neuropsychology and psychiatry.

This review describes recent advances in the application of rCBF measurements by the 133Xe-inhalation method to neuropsychological and psychiatric research. Studies mapping cortical activity, as indicated by flow variations during visual, auditory and tactile tasks of varying complexity are described. The bilateral rCBF measurements do also offer information concerning lateralization of mental processes. Some clinical applications in psychiatry are finally reviewed demonstrating the use of the technique in differential diagnosis of dementia of organic ethiology (Alzheimer's disease, multi-infarct dementia) against pseudodementia due to psychosis. The method is also very useful in the study of cases with toxic influence by alcohol and other agents.

Auditory Perception↗