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Biomedical subjects

A Zitting

Publications and source records attributed to A Zitting.

At least 37 records · Page 2Linked to original sources
PubMed1987

Acute biological effects of commercial cresyl diphenyl phosphate in rats.

A commercial cresyl diphenyl phosphate preparation was analyzed to contain approximately 35% of triphenyl phosphate, 45% of cresyl diphenyl phosphates, 18% of dicresyl phenyl phosphates and 2% of tricresyl phosphates. The product was almost free of the o-cresyl isomers as revealed by the analysis of its alkaline hydrolysis products. A single intraperitoneal injection (150 or 300 mg/kg) caused an induction of microsomal cytochrome P-450 in the liver of Wistar rats with a concomitant increase in the activities of mixed function monooxygenases and proliferation of smooth endoplasmic reticulum 24 h after the treatment. These effects were not detected in the kidneys. The morphological changes in hepatocytes included the enlargement of nuclei and mitochondria with increased cristae. The hepatic morphology returned to normal 2 weeks after the treatment. The activity of pseudocholine esterase in blood was inhibited 4 h and 24 h after the injection but the effect levelled off. The concentration of the organophosphates in blood and liver decreased rapidly with only traces detected in blood after 24 h. No effects on the activities of cerebral and muscle acetylcholine esterase were observed. The treatment (300 mg/kg) inhibited the brain--2',3'-cyclic nucleotide 3'-phosphohydrolase through the 2-week observation period associated with demyelination in peripheral nerves.

Animals↗
PubMed1986

Metabolic changes in rat brain synaptosomes after exposure to sulfide in vivo.

The effects of exposure of rats to sulfide and the action of exogenous heme were studied in rat-brain synaptosomes. Exposure to sulfide impaired the respiration of synaptosomes which was reversed by heme (4 mg/kg body weight). Sodium sulfide caused partial inhibition of gamma-aminobutyric acid (GABA) and dopamine uptake, strongly inhibited veratridine-dependent release of these neurotransmitters and reduced veratridine-dependent changes in transmembrane electrical potential. Heme treatment did not reverse these changes.

Animals↗
PubMed1985

The brain octopamine and phenylethanolamine content in rats in thioacetamide-induced hepatogenic encephalopathy.

The brain octopamine (OA) and phenylethanolamine (PhEA) content was determined in rats subjected to repeated intraperitoneal administrations of thioacetamide (TAA) known to produce different stages of hepatogenic encephalopathy (HE). A more than 2.5-fold increase of OA and a 2-fold increase of PhEA was observed after prolonged (3 times) administration of TAA, coinciding with impaired ammonia detoxication in brain and with the onset of pathophysiological changes typical for HE. Only insignificant changes in the content of the amines were observed in the early stages of the experiment as well as in the recovery period. The results are consistent with the "false neurotransmitter" hypothesis of Fischer and Baldessarini, assuming the participation of OA and PhEA in the pathogenesis of HE.

2-Hydroxyphenethylamine↗
PubMed1984

DNA binding of [14C]styrene in isolated rat hepatocytes.

Incubation of hepatocytes from phenobarbital-pretreated rats with diethylmaleate (DEM) and 1 mM [14C]styrene for 3 to 5 hours did not result in binding of styrene 7,8-oxide (SO) to DNA as determined by ion exchange chromatography of enzymatic digests of DNA. The elution of substantial amounts of radioactivity together with natural nucleosides and bases suggests that styrene is partly metabolized via splitting of the vinyl bond and that incorporation of C1 fragments into DNA is most likely the result of repair DNA synthesis following DNA damage by styrene itself or one of its metabolites.

Animals↗
PubMed1984

Toxicity of polymethylmethacrylate thermodegradation products.

Polymethylmethacrylate was thermally degraded in air at 300 degrees C and the volatile decomposition products studied with gas chromatography-mass spectrometry. The main product was monomeric methacrylate, although many other compounds existed among the products. Electron spin resonance spectroscopy revealed the presence of free radicals. Wistar rats were exposed to the fumes of the plastic (300 degrees C) and their lungs and brain studied for biochemical effects. In the lung, the activity of 7-ethoxycoumarin O-deethylase decreased and an initial inhibition of glutathione peroxidase and superoxide dismutase was observed. The contents of reduced nonprotein sulfhydryl groups were decreased in the lung and brain. The exposures enhanced the activities of acetylcholine esterase, creatine kinase and NADPH-diaphorase in the brain. Scanning electron microscopy of the exposed lungs showed disorganization of ciliated cells, and the epithelial serous cells (Clara cells) were damaged.

Animals↗
PubMed1984

Trinitrotoluene-induced effects on rat heme metabolism.

A single injection (100 mg/kg body wt) of trinitrotoluene in rats caused decreased delta-aminolevulinic acid synthase activity in reticulocytes and decreased erythrocyte coproporphyrin concentration 48 hr after the intraperitoneal dosage. For comparison, liver delta-aminolevulinic acid synthase was unaffected while heme synthase activity was below the control range at the same time. Heme oxygenase activity increased simultaneously. These effects are likely to lead to a negative heme balance and may be developed for a biological exposure test to trinitrotoluene in occupational health service.

5-Aminolevulinate Synthetase↗
PubMed1984

Symptoms of vibration syndrome and radiographic findings in the wrists of lumberjacks.

In a cross sectional study 279 lumberjacks exposed to chain saw vibration and a reference group of 178 peat bog workers were examined. The mean ages of the two groups were 34.6 and 33.1 years, respectively. The lumberjacks' mean duration of exposure to vibration was 10.4 years. The study consisted of a questionnaire and a clinical examination, including radiographs of the wrists. The prevalence of reported white finger symptoms was 18% for the lumberjacks and 3% for the referents, whereas that of numbness in the upper extremities was 51% and 22%, respectively. Among lumberjacks the occurrence of white finger symptoms increased significantly with the duration of exposure to vibration but was not associated with age or smoking. The prevalence of the numbing of the upper extremities increased linearly with age in both groups, but it was not associated with duration of exposure after adjustment for age. Among lumberjacks there was a significant association between the numbing symptom and the white finger symptom, but not among the referents. A high prevalence of numbing in the upper extremities among the lumberjacks could be at least partly explained by occupational factors other than vibration--work posture, for example. Radiographically, cysts were found in the wrist bones of 8-9% of both groups. The exposure to chain saw vibration no longer seems to be a determinant in the development of vacuoles in the carpal bones.

Adult↗
PubMed1984

Extrinsic allergic alveolitis in the tobacco industry.

A total of 57 subjects who had been exposed to mould dust in the tobacco industry were studied. Their working environment showed exposure to spores of different moulds, and 29 subjects (51%) showed antibodies against one or more of the microbes. Fifteen (26%) had work related respiratory symptoms. Eight (14%) showed slight radiographic pulmonary fibrosis. Spirometry showed a tendency toward restriction and obstruction, especially in small airways. Diffusion capacity was decreased in 18% of the workers. Three clinical cases of typical allergic alveolitis were also found. All this suggests that exposure of spores of different moulds (especially Aspergillus fumigatus) in the manufacture of tobacco products may induce symptoms and signs relating to extrinsic allergic alveolitis.

Adult↗
PubMed1984

Rarity of mineral fibre pleurisy among persons exposed to Finnish anthophyllite and with low risk of mesothelioma.

Endemic pleural plaques are reported from many parts of the world. In Central Europe and in Finland no connection with malignant mesotheliomas has been found, whereas this tumour is often encountered in areas in Turkey where endemic plaques also occur. There seem, however, to be differences in the radiological appearances found in these areas. In the present study chest radiographs of 317 persons with pleural plaques from the endemic area of Finland were scrutinized. It was found that 4.7% showed a blunted costophrenic angle unilaterally and 0.9% bilaterally. The prevalence of sequelae of pleurisy is statistically very highly significantly lower than in people with pleural plaques in Turkey. As the risk of mesothelioma appears to be low in Finland, the results are in accordance with the hypothesis that the risk of mesothelioma in a given population is higher if in that population there is a high incidence of benign asbestos pleurisy.

Adolescent↗
PubMed1984

Analytical, occupational and toxicologic aspects of the degradation products of polypropylene plastics.

Thermooxidative degradation of polypropylene (PP) at close to the industrial processing temperatures was studied with thermogravimetric analysis, infrared spectroscopy, and gas chromatography-mass spectrometry (GC-MS). GC-MS allowed identification of 47 volatile degradation products. Formaldehyde, acetaldehyde, alpha-methylacrolein, acetic acid, and acetone were the major products. Antioxidants markedly slowed down the degradation of polypropylene and the evolution of the degradation products. The relative amounts of the oxidized products were mostly independent of the degradation temperature or the type of antioxidant. Measurements in the plastics industry revealed low airborne concentrations of individual volatile products. The concentration of aerosols, which infrared analysis showed to resemble paraffin fumes, was significant and probably the most important hygienic hazard. The biochemical parameters (the consumption of protecting sulfhydryl groups and the effects on foreign compound metabolism) indicated that the degradation products are biologically reactive, affecting the balance of normal metabolism in exposed animals.

Air Pollutants, Occupational↗
PubMed1984

Serum beta-N-acetylglucosaminidase and beta-glucuronidase activities in silicosis patients and in workers exposed to silica dust.

The serum activities of two lysosomal enzymes, beta-N-acetylglucosaminidase (EC 3.2.1.30; NAG) and beta-glucuronidase (EC 3.2.1.31; GLU) were analysed in 116 male patients with silicosis. Twenty-eight of the patients were matched with controls of similar sex, age and exposure to silica dust but with no radiographical evidence of silicosis. A control group which had not been exposed to silica dust consisted of male blood donors. The mean activity of NAG in serum was higher in the silicosis patients than in the blood donors (P less than 0.01). Similarly, the NAG level in the silicosis patients with matched controls was higher than that in the silica-exposed controls (P less than 0.05). The silicosis patients who showed a progression of small opacities by one or more subcategories had a slightly higher mean NAG activity in their sera than the patients with no progression but this difference did not reach statistical significance; the activity was higher than in silica-exposed controls (P less than 0.05). We suggest that these findings may be related to the effects of silica on macrophages which have been observed experimentally in vitro and in vivo and might indicate an increased turnover of macrophages caused by silica dust and active, progressive silicotic fibrosis.

Acetylglucosaminidase↗
PubMed1983

Wollastonite exposure and lung fibrosis.

Wollastonite is a naturally occurring acicular or fibrous metasilicate used in ceramics and as a substitute for asbestos in some applications. Wollastonite fibers are rather similar in form, length, and diameter to amphibole asbestos fibers but mineralogically they are different. Dust measurements in both the Finnish limestone--wollastonite quarry and in the flotation plant yielded high concentrations of both total dust and respirable fibers in some operational stages. The clinical study comprised a total of 46 men who had been exposed to wollastonite at the quarry for at least 10 years. Three of the fifteen nonsmokers showed chronic bronchitis. Radiographs revealed slight lung fibrosis among fourteen men, and slight bilateral pleural thickening among thirteen men. Their sputum specimens were normal. Spirometry and nitrogen single breath tests indicated the possibility of small airways disease.

Adult↗
PubMed1983

Knee degeneration in concrete reinforcement workers.

The loads on the knees in concrete reinforcement work and maintenance painting were analysed on eight construction work sites. A total of 352 reinforcement workers and 231 painters. Finnish men aged 20-64, were clinically and radiologically examined to determine the condition of the knee joints in active workers. The loads on the knees and the occurrence of minor injuries and accidents were higher in reinforcement work than in painting, but the occurrence of symptoms, clinical signs, and radiological findings was equally common in both groups. Reinforcement work seemed to provoke more symptoms from degenerated knees than painting.

Adult↗
PubMed1982

Comparison of acute toxic effects of intraperitoneally injected nitromethane and nitroethane in rats.

Male 3-month-old Wistar rats dosed i.p. with 200 mg/kg of nitromethane or -ethane showed increased acid proteinase activity in the brain 4 h after the injection. The change was accompanied by a marginal increase in the cerebral glutathione concentration. Nitroethane caused enhanced epoxide hydrolase and UDP-glucuronosyltransferase activity in the hepatic microsomal fraction up to 48 h while 7-ethoxycoumarin o-deethylase decreased. These biochemical changes were accompanied by proliferation of smooth endoplasmic reticulum and degranulation and disorganization of the rough endoplasmic reticulum of the nitroethane-exposed liver cells. The hepatic effects of nitromethane were restricted to decreased cytochrome c reductase activity with proliferation of smooth endoplasmic reticulum. The results point at limited peroxidative damage possibly involving reduction of the nitrogroup.

7-Alkoxycoumarin O-Dealkylase↗