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Biomedical subjects

P Orbaek

Publications and source records attributed to P Orbaek.

34 records · Page 2Linked to original sources
PubMed1989

Elimination of toluene from venous blood and adipose tissue after occupational exposure.

In a group of 37 rotogravure printers a close correlation (rs = 0.78) was found between the time weighted toluene exposure during a five day working week (range 8-416 mg/m3, median 75) and the concentration of toluene in subcutaneous adipose tissue (range 1.1-20.7 mg/kg, median 3.8). After exposure ceased, the elimination of toluene was followed up in 11 subjects. The toluene concentration in venous blood decreased non-linearly and the elimination curves contained at least three exponential components. The first two had median estimated half times of nine minutes and two hours respectively. The third component, with a median half time of 90 hours, reflected the decline in adipose tissue, which had a median half time of 79 hours (range 44-178). The study showed protracted endogenous toluene exposure from adipose tissue depots long after the end of exogenous exposure. The observations also suggest that the blood toluene concentrations on Monday mornings might be used as an index of the exposure in the previous week.

Adipose Tissue↗
PubMed1989

Finger receptor dysfunction in dental technicians exposed to high-frequency vibration.

The effects of high-frequency vibration (up to 40 kHz) on digital nerve function were studied in ten dental technicians and ten age-matched referents. Nerve conduction velocities, including fractionated antidromic measurements over the carpal tunnel, showed no difference between the groups. In the group of dental technicians the difference between the response latency of the mechanical and electric stimuli in the median nerve distally on the fingers of the right hand was slightly higher than in the reference group, and therefore distal nerve or receptor dysfunction was suggested. Vibration warming and cooling thresholds were significantly increased and thus revealed damage to both myelinated and unmyelinated fibers in the fingers of subjects exposed to high-frequency vibration.

Adult↗
PubMed1989

Regional cerebral blood flow at the time of diagnosis of chronic toxic encephalopathy induced by organic-solvent exposure and after the cessation of exposure.

Regional cerebral blood flow was measured in patients with the diagnosis of chronic toxic encephalopathy induced by exposure to organic solvents. Measurements were made at the time of diagnosis and 24-84 months after the cessation of exposure. During the follow-up the patients were carefully examined for other possible causes of brain dysfunction. Comparisons were made to unexposed and solvent-exposed referents. At the first examination the patients had a 7% lower mean flow level than the unexposed referents and a 5% lower level than the exposed workers. The largest flow differences were seen in the frontotemporal areas. At the follow-up, the difference in the mean flow level between the patients and referents was no longer significant. Regionally, the flow had increased, especially in areas which initially showed the most pronounced decreases. There was a significant negative correlation between the initial cerebral blood flow level and the degree of normalization of the flow level at follow-up.

Adult↗
PubMed1988

Railroad workers with pleural plaques: I. Spirometric and nitrogen washout investigation on smoking and nonsmoking asbestos-exposed workers.

Eighty-seven workers exposed to asbestos in a railroad car repair shop, with characteristic asbestos-induced pleural plaques, underwent extensive lung-function examination. Vital capacity (VC) showed the greatest reduction among the static lung volumes, with an asymmetrical distribution of one-fourth of the subjects below 80% of the predicted value. Logistic regression demonstrated VC to be sufficient for optimal discrimination of asbestos-exposed subjects from a group of matched controls. No further discriminatory power was gained by additional spirometric measures, lung mechanics, blood gas analysis, or diffusing capacity. Smoking had an influence on dynamic but not on static lung volumes. In conclusion, reduced static lung volumes among smoking asbestos-exposed workers with pleural plaques should, in the absence of other lung diseases, be mainly attributed to the asbestos exposure.

Adult↗
PubMed1988

Railroad workers with pleural plaques: II. Small airway dysfunction among asbestos-exposed workers.

Increased volume of trapped gas (VTG) was found in 87 asbestos-exposed railroad repair shop workers, divided into three subgroups according to smoking habits. All the examined subjects had pleural plaques. Determination of VTG was used to study function of small airways. Increased VTG was found among asbestos-exposed smokers as well as nonsmokers. In both groups the VTG:TLC ratio was elevated compared with controls. Increased VTG is a sign of small airways dysfunction. In asbestos-exposed subjects, it might be caused by an early peribronchial reaction to inhaled asbestos fibers.

Adult↗
PubMed1988

Toluene in venous blood during and after work in rotogravure printing.

Toluene exposure was studied in 62 male rotogravure printers, employed in three plants. The exposure level as measured by personal sampling during a week ranged from 8 to 1080 mg/m3 (median 96). The concentration of toluene in venous blood sampled directly after work correlated significantly with the time-weighted average (TWA) for toluene in air during the preceding workshift (n = 57, Spearman's r = 0.84, P less than 0.00001). The post-shift toluene level in venous blood is usable for biological monitoring of exposure. An air level of 100 mg/m3 corresponds to an average blood toluene level of 2.9 mumol/l; an air level of 300 mg/m3 to 8.2 mumol/l. The elimination of toluene is slow. Thus, toluene was detected in most Monday pre-shift blood samples and the levels increased statistically significantly during the work week (median 0.21 versus 0.42 mumol/l, P less than 0.0001). The toluene level in venous blood sampled directly before work on Thursday/Friday was found to be a function of the estimated mean exposure during the work week. In a multiple linear regression analysis, the mean exposure during the week was a good predictor for the concentration of toluene in venous blood before work at the end of the week (n = 52, r = 0.71). Thus, pre-shift blood values at the end of the week can be used as a biological index for the weekly exposure, when the variation of the ambient toluene concentration is known. The slow decrease of toluene in venous blood was followed in six workers for two weeks after cessation of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Electroneurographic findings in patients with solvent induced central nervous system dysfunction.

The function of the peripheral nervous system was examined in a group of 32 men aged 30-65 (mean 49) with diagnosed solvent induced chronic toxic encephalopathy. The subjects were examined at the time of diagnosis and 26 were re-examined after a follow up period of 22-72 months (mean 40) and compared with a group of 50 unexposed male workers aged 27-64 (mean 42) with appropriate adjustment for age. All subjects were carefully scrutinised for alcohol abuse and other neurological diseases. The results of motor fibre neurography disclosed no difference between the groups. Nevertheless, a significant decrease in motor conduction velocity was found in the patients at follow up. Sensory fibre neurography showed signs of slight axonal degeneration with significantly decreased sensory nerve action potential amplitudes in the median and sural nerves; these amplitudes increased during follow up. The duration of sensory nerve action potentials was longer in the exposed group for the median and the sural nerves. The percentage of late components was significantly higher in the median nerve. The warm-cold sensitivity in the exposed group also indicated a slight sensory dysfunction with statistically significant wider detection limits.

Action Potentials↗
PubMed1988

Power spectrum analysis of EEG at diagnosis and follow up of patients with solvent induced chronic toxic encephalopathy.

Electroencephalographic changes have been studied in a group of 32 men aged 30-65 (mean 49) with diagnosed chronic toxic encephalopathy. The group had been carefully scrutinised for other possible causes of brain dysfunction and the diagnosis was based on neuraesthenic symptoms and pathological psychometric performance. The EEGs were recorded from four areas of the brain and the power spectrum analysed. Comparisons have been made with a group of 50 healthy male workers with no occupational exposure to solvents. For 24 of the 32 patients a follow up EEG recording was made after 17-75 months (mean 33). The results showed a doubling of the EEG power in the patients for all four recording channels with a significant reduction at follow up but not to the level of the control group. No exposure effect relation could be established. Acute exposure at the time of the first recording, exposure free, or follow up time did not influence the results. The frequency of the dominant EEG activity and the relative frequency distribution were equal in the two groups and did not change during the follow up period. Five of the 32 subjects took benzodiazepine drugs regularly and they had greater total power in all four recording channels compared with the other 27 patients; the difference was not statistically significant. The relative frequency distribution showed less alpha- and more theta- and beta-power in these five subjects. A reduction in total power during follow up was also found in the subgroup that took benzodiazepines.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Prospective clinical and psychometric investigation of patients with chronic toxic encephalopathy induced by solvents.

Sixty-two patients with chronic toxic encephalopathy diagnosed in 1976-1981 were considered for reexamination in 1983-1984. Thirteen were found to have other diseases that might contribute to brain dysfunction. Seventeen were unwilling or unable to participate. The final group consisted of 32 men 33 to 63 (median 55) years of age who were physically and psychometrically reexamined with the same methods used in the initial investigation. The interval between the first and present examination was 21-88 (median 48) months, and exposure to solvents had ceased. The subjects reported some improvement in their neurasthenic problems. In particular they suffered less from fatigue, headache, and dizziness. When diagnosed they had an average of seven out of ten typical neurasthenic symptoms included in the toxic encephalopathy syndrome. At the time of the follow-up the mean number of symptoms had decreased significantly to five. The psychometric retesting showed significant deterioration in verbal memory, improvement in visual memory, and unchanged results on the other tests. In conclusion, these toxic encephalopathy patients improved subjectively when exposure stopped. Psychometrically they performed very close to the initial testing, which excluded progressive brain disease or subacute pharmacological solvent intoxication.

Adult↗
PubMed1987

Small airway hyperreactivity among lifelong non-atopic non-smokers exposed to isocyanates.

The development of isocyanate asthma is little understood. To gain more knowledge in this area, a group of 20 workers occupationally exposed to isocyanates, five subjects with clinical isocyanate asthma, and a control group of 10 people not exposed to isocyanate were examined with lung function tests and a methacholine provocation test. Forced expiratory volume in one second and tests aimed at detecting small airways obstruction such as volume of trapped gas, closing volume, and wash out volume were made. To detect abnormal airway reactivity, tests were made before and after inhalation of methacholine and of salbutamol. A significant increased reactivity to methacholine in the exposed and asthma groups was seen compared with the control group as measured by volume of trapped gas. The increase was reversed by inhaling salbutamol. In neither group could a statistically significant reaction be shown in the large airways. The study group had increased small airways reactivity of the same magnitude as the group with isocyanate asthma. The subjects in the study group had no clinical symptoms or spirometric abnormalities. The volume of trapped gas in combination with methacholine seems to disclose significantly altered reactivity of the small airways in workers exposed to isocyanate with no subjective symptoms of disease.

Adult↗
PubMed1987

Computed tomography and psychometric test performances in patients with solvent induced chronic toxic encephalopathy and healthy controls.

Patients with chronic toxic encephalopathy caused by occupational exposure to organic solvents and diagnosed between 1976 and 1981 have been re-examined during a follow up period of 21-88 months (median 48). Thirty two patients underwent computed brain tomography (CT), were retested psychometrically, and the results were compared with a group of age matched control subjects from the same socioeconomic level. The age of the patients was 33-69 (median 55) and they had been exposed to organic solvents for 7-50 years (median 26). The CT examinations were quantified by linear measurements on the films of the four largest sulci, the minimum width of the cella media and the third ventricle. Bifrontal horn, bicaudate, and third ventricle--Sylvian fissure distances were also measured; and measurements were adjusted for variation in skull diameter. No differences were found between the patients and controls. Most of the measures were correlated with age, to a somewhat higher degree in the patients. The patient-control differences did not increase with increasing age of the subjects. Psychometrically the patients performed worse than the controls despite adjustments for possible differences of intellectual level in the two groups. In the patients correlations were found between some of the CT measures and psychometric test performances suggesting slower psychomotor speed and attention difficulties among subjects with central and cortical brain substance reduction. No such correlation was found in the control group. It is concluded that patients with solvent induced chronic toxic encephalopathy have no severe loss of brain substance.

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↗
PubMedDate not supplied

Chronic toxic encephalopathy: social consequences and experiences from a rehabilitation program.

This study evaluates a rehabilitation program designed to address the social function issues of patients with solvent-induced chronic toxic encephalopathy (TE) and their families. Fourteen newly diagnosed men and their spouses participated in group sessions. The patients were given cognitive training, and crisis intervention measures were implemented. Their spouses were given information about the disease and had an opportunity to talk about their emotions and the disease's impact on the family's functioning. Interviews after the program showed that patients and their spouses were experiencing less psychological distress and increased social activity and had begun reestablishing contacts with friends. Their psychiatric symptoms, measured during a structured interview by a nurse, decreased significantly immediately after the treatment period but increased again after 6 months. Only a long-term follow-up study comparing the experiences of these patients with those of untreated TE patients can determine whether improvement can be sustained over the long term.

Adult↗