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Biomedical subjects

T Kumlin

Publications and source records attributed to T Kumlin.

At least 19 recordsLinked to original sources
PubMed1998

Effects of 50 Hz magnetic fields on UV-induced skin tumourigenesis in ODC-transgenic and non-transgenic mice.

PURPOSE: To study the possible role of 50 Hz magnetic fields (MF) in UV-induced skin tumourigenesis using a sensitive animal model. MATERIALS AND METHODS: Transgenic mice (line K2) over-expressing the human ornithine decarboxylase (ODC) gene and their non-transgenic littermates were exposed for 10.5 months to UV-only or a combination of UV and a continuous (100 microT) or an intermittent MF with varying intensity (1.3-130 microT). RESULTS: Both MF exposure and transgenicity enhanced the onset rate of macroscopically detectable tumours, but the effect was statistically significant only for the MF exposure (p < 0.015). The number of animals bearing malignant tumours was low and similar in all exposure groups. Epidermal cysts (EC) appeared to be strongly associated with both MF exposure and high ODC activity (transgenic animals). However, EC are not known to be associated with carcinogenesis. The UV-only or combined UV and MF exposure did not affect the ODC activities measured at the end of the exposure. CONCLUSIONS: These results support the proposed tumour-promoting effect of MF, but do not suggest an important role for increased ODC activity in this process.

Animals↗
PubMed1998

Epidermal ornithine decarboxylase and polyamines in mice exposed to 50 Hz magnetic fields and UV radiation.

We studied the influence of magnetic fields (MFs) and simulated solar radiation (SSR) on ornithine decarboxylase (ODC) and polyamines in mouse epidermis. Chronic exposure to combined MF and SSR did not cause persistent effects on ODC activity or polyamines compared to the animals exposed only to UV, although the same MF treatment was previously found to accelerate skin tumor development. In an acute 24-h experiment, an elevation of putrescine and down-regulation of ODC activity was observed in the animals exposed to a 100-microT MF. No effect was seen 24 h after a single 2-MED (minimal erythemal dose) exposure to SSR. The results indicate that acute exposure to 50 Hz MF does exert distinctive biological effects on epidermal polyamine synthesis.

Analysis of Variance↗
PubMed1994

Distribution and short-term effects of intratracheally instilled neutron-irradiated UO2 particles in the rat.

In the present study we investigated the radionuclide distribution and histopathological effects of neutron-irradiated UO2 particles in the rat after intratracheal instillation. The kinetics and short-term effects of uranium fission products (95Zr, 95Nb, 103Ru, and 141Ce) were examined during a 3-month follow-up period. A rapid clearance (about 21%) of particles occurred via the gastrointestinal tract within 24 hr after the instillation. Autoradiographic and histological examinations revealed that the retained particles were nonuniformly distributed in the lungs. Translocation of the fission products from the lung to various other tissues was slow; 3 months after the instillation, the activity of the total body burden was below 1% in the liver, kidney, and spleen, whereas in the lungs it was 83%. Clearance of particles appeared to be mainly due to tracheobronchial mucociliary mechanisms. Translocation of the fission products to the bone and liver was significantly less than that reported by the ICRP, indicating that the clearance of uranium-matrix-associated fission products is preferably dependent on the physical characteristics of the particulate material. The cumulative lung doses ranging from 170 to 550 mSv caused slight or moderate local inflammatory reactions in the lungs, but at smaller dose levels there were no histopathological changes observed.

Animals↗
PubMed1985

Multifactorial primary prevention of cardiovascular diseases in middle-aged men. Risk factor changes, incidence, and mortality.

In a randomized five-year multifactorial primary prevention trial of vascular diseases, hyperlipidemias, hypertension, smoking, obesity, and abnormal glucose tolerance of the high-risk test group (n = 612 men) were treated with dietetic-hygienic measures and hypolipidemic (mainly probucol and clofibrate) and antihypertensive (mainly diuretics and beta-blockers) agents. A matched high-risk control group (n = 610) and a low-risk control group (n = 593) were not treated. The program markedly improved the risk factor status, yet the five-year coronary incidence tended to be higher in the intervention group than in the control group (3.1% vs 1.5%), while the stroke incidence was significantly reduced (1.3% vs 0%). The coronary events tended to be accumulated in subgroups treated with beta-blocking agents or clofibrate, but there were few in those receiving probucol or diuretics. Thus, the intervention program significantly reduced development of stroke, but the occurrence of cardiac events was not prevented. Possible adverse drug effects offsetting the probable benefit of improved risk profile are not excluded.

Antihypertensive Agents↗
PubMed1983

Serum selenium concentration related to myocardial infarction and fatty acid content of serum lipids.

A longitudinal case-control study of 33 patients with one or more risk factors for coronary heart disease and 64 controls showed that the serum selenium concentration (range 0.63-1.33 mumol/l (50-105 micrograms/l] was not associated with development of clinical manifestations of coronary heart disease during a follow up of five to seven years. The content of polyunsaturated fatty acids, especially eicosapentaenoic acid, in serum cholesterol esters and phospholipids was positively correlated with selenium concentration. As a low content of polyunsaturated fatty acids in serum lipids was an independent risk factor for coronary heart disease in these subjects it may be hypothesised that the high coronary risk in subjects with a very low serum selenium concentration (less than 0.57 mumol/l (less than 45 micrograms/l] might be due not to selenium deficiency but to the coexisting low concentrations of polyunsaturated fatty acids in serum.

Cholesterol Esters↗
PubMed1982

Fatty-acid composition of serum lipids predicts myocardial infarction.

During a follow-up of five to seven years 33 out of 1222 middle-aged men initially free of coronary heart disease sustained fatal or non-fatal myocardial infarction or died suddenly. The fatty-acid composition of serum triglycerides, phospholipids, and cholesterol esters had been measured at the start of the surveillance in these men and in a control group of 64 men matched for age, serum cholesterol and triglyceride concentrations, blood pressure, obesity, smoking, and one-hour glucose tolerance. Palmitic and stearic acids of phospholipids were significantly higher and linoleic and most polyunsaturated fatty acids, including arachidonic acid and eicosapentaenoic acid, of phospholipids were lower in the subjects who sustained coronary events compared with the controls. Linoleic acid tended to correlate negatively with blood pressure while other polyunsaturated fatty acids, especially eicosapentaenoic acid, exhibited a negative correlation with blood pressure and relative body weight in the controls but not in the subjects who sustained coronary events. These findings suggest that the fatty-acid pattern of serum phospholipids is an independent risk factor for coronary heart disease.

Adult↗
PubMed1982

HDL cholesterol and beta-adrenoceptor blocking agents in a 5 year multifactorial primary prevention trial.

1 Serum HDL cholesterol measured at the end of a 5 year multifactorial primary prevention trial, aimed to reduce risk factor levels and incidence of ischaemic heart disease, revealed quite low values in drug-treated subjects. 2 Analysis of subgroups treated with beta-adrenoceptor blocking agents (mainly pindolol) alone or in different combinations with diuretics showed inconsistent effects of beta-adrenoceptors blockers on serum HDL cholesterol. HDL cholesterol levels in patients treated with pindolol with or without a diuretic were not different from those of the risk-free control group. 3 Subjects on combined beta-adrenoceptor blocker-hypolipidaemic treatments had lower HDL-cholesterol than those on hypolipidaemic agents alone. 4 Withdrawal of pindolol at the end of the trial caused a small but significant increase in serum HDL cholesterol in a small subgroup of mildly hypertensive patients. Thus, pindolol appears to have slightly reduced serum HDL cholesterol but the relevance of this small decrease on the incidence of ischaemic heart disease is questionable.

Adrenergic beta-Antagonists↗
PubMed1981

Effect of probucol on the activity of postheparin plasma lipoprotein lipase and hepatic lipase.

The effect of discontinuation of long term (34-56 months) probucol treatment on serum lipids, lipoproteins and on the activity of postheparin plasma lipoprotein and hepatic lipase ahs been studied in 10 healthy males participating in a primary prevention programme of coronary heart disease. A significant increase was observed in the activity of postheparin plasma lipoprotein lipase, in the total serum cholesterol concentration and in the serum concentrations of high density lipoprotein (HDL) cholesterol, HDL phospholipids and apoprotein AI after withdrawal of the drug No changes were seen in the serum triglyceride levels or in the activity of postheparin plasma hepatic lipase. The activity of postheparin plasma hepatic lipase tended to correlate with the serum concentration of HDL. No correlations were present between the individual changes in the serum levels of HDL and in the activity of postheparin plasma triglyceride lipases.

Apolipoprotein A-I↗
PubMed1980

Effect of long-term antihypertensive and hypolipidemic treatment on high density lipoprotein cholesterol and apolipoproteins A-I and A-II.

The concentrations of total serum cholesterol and triglycerides and serum HDL cholesterol, triglycerides and apoproteins A-I and A-II were measured in 119 men after 4 years of active participation in a multifactorial primary prevention trial of coronary heart disease. No difference was observed in total serum cholesterol, triglycerides, HDL lipids or apoproteins between the control subjects without medication and the men treated with antihypertensive drugs (beta-blockers alone or in combination with thiazides). The concentration of HDL cholesterol was significantly lower and that of apoprotein A-II significantly higher in the individuals treated with clofibrate than in the controls. On the other hand, the levels of both HDL cholesterol and apoprotein A-I were lower in the men treated with probucol than in the controls, whereas that of A-II was within the control limits. The ratio HDL cholesterol/apoprotein A-I was subnormal in all 3 groups treated with lipid-lowering drugs, as if the treatment had lowered the cholesterol saturation of the HDL fraction. The levels of HDL cholesterol and apoprotein A-I were negatively correlated with the length of the treatment in subjects treated with probucol but not in the other groups. These results suggest that in long-term use, probucol and possibly clofibrate lower both the concentration and the cholesterol/apoprotein ratio of the HDL fraction.

Antihypertensive Agents↗