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Biomedical subjects

P Hansson

Publications and source records attributed to P Hansson.

At least 91 records · Page 5Linked to original sources
PubMed1984

A thin-section and freeze-fracture study of the pulp blood vessels in feline and human teeth.

The fine structure of blood vessels with a diameter of less than 50 micrometers, i.e. small arterioles, capillaries and postcapillary venules were studied. The number of pinocytotic vesicles was greater in capillary endothelium than in arterioles and venules. There was regional variation in vesicle frequency in capillary endothelial cells (arteriolar and venule cells not studied). Fenestrations and pinocytotic vesicles were closely associated in some capillary-endothelial membrane areas and segmental differentiation of tight junctions (zonula occludens) in the vascular endothelium. The arteriolar tight junctions were classified as relatively tight, capillary junctions as leaky and venule junctions as very leaky. No nexuses (gap junctions) were found in the endothelium. Only four nexuses were found in the arteriolar smooth-muscle cells. Perivascular fibrocytes were frequently interconnected with nexuses. Nerve fibres in the vicinity of blood vessels contained granular and clear vesicles. The narrowest gap between vesicle-containing nerves and smooth-muscle cells was 0.3 micrometer. No specialized contacts were found between nerve fibres and vascular cells. Solitary cilia with a 9 + 0 pattern were occasional in capillary endothelial cells fibroblasts and odontoblasts. Only one arterio-venous anastomosis was found.

Adolescent↗
PubMed1984

The influence of mechanical vibratory stimulation and transcutaneous electrical nerve stimulation on experimental pruritus induced by histamine.

The effect of conditioning mechanical vibratory stimulation and transcutaneous electrical nerve stimulation (TENS) on experimentally induced pruritus was studied on 12 healthy subjects. Pruritus was provoked by intradermal injection of histamine on the upper arm. Vibration at 10, 100 and 200 Hz and TENS at 2 and 100 Hz were applied (i) over or (ii) proximal (in the same dermatome) to the pruritic area for a period of 5 min following itch elicitation. In addition the influence of a 5 min pre-stimulatory regimen of the injection area was investigated (iii). The results obtained were compared with unconditioned values and with those obtained following a placebo conditioning procedure (i, ii). It was found that vibratory as well as electrical stimulation, for all frequencies used, reduced subjective itch intensity. Vibration at 100 Hz was the most effective mode of stimulation especially when applied directly to the pruritic area. Conditioning with 100 Hz vibration was also the most effective mode for reducing the duration of the itch response as well as the total experience of pruritus (estimated as a total itch index). Induction time to partial and maximal itch alleviation was shortest for 100 Hz vibration. The results indicate that treatment of pruritic conditions with conditioning stimulation, especially vibration, may be of therapeutic interest.

Adult↗
PubMed1983

Influence of nutritional state on lipoprotein lipase activities in the hypothyroid rat.

We have investigated the effects of nutritional state on the lipoprotein lipase activities of the experimentally hypothyroid rat. Both short-term effects (i.e., those of a 24 h fast with and without re-feeding) and long-term effects (due to decreased food intake in hypothyroidism) have been studied. The hypothyroid rats had significantly higher lipoprotein lipase activities of adipose tissue and heart muscle. The effect of hypothyroidism on adipose tissue lipoprotein lipase activities was modified by the nutritional state. In rats studied after 24 h fasting, the hypothyroid group had significantly higher lipoprotein lipase activities than weight-matched, age-matched and pair-fed (i.e., semi-starved) control groups. In rats studied in the re-fed state, the effects of hypothyroidism as such were less evident, since the pair-fed group also demonstrated significantly higher enzyme activities than did the other control groups. We have also studied the lipoprotein lipase activities of different enzyme preparations from adipose tissue. The effects of hypothyroidism were most clearly reflected in an increase of heparin-elutable enzyme activity from adipose tissue, whereas adipocyte lipoprotein lipase activity and the lipoprotein lipase secretion rate from adipocytes were affected to a lesser extent. We conclude that alterations in food intake strongly influence the lipoprotein lipase activities in the hypothyroidism. Our data also imply that the increased lipoprotein lipase activity in the hypothyroid state is due to a decreased degradation of the enzyme, both intra- and extracellularly.

Adipose Tissue↗
PubMed1983

Plasma lipoproteins and lipolytic enzyme activities during endurance training in sedentary men: changes in high-density lipoprotein subfractions and composition.

Eighteen healthy sedentary males took part in supervised bicycle training for 50 minutes three to five times a week. Twelve subjects (group A) trained for 6 weeks at heavy intensity, and six subjects (group B) trained for 12 weeks at moderate intensity. Maximal oxygen uptake increased by about 20% (P less than 0.01). Body weight and composition as well as diet remained unchanged. After 6 weeks plasma high-density lipoprotein (HDL) cholesterol concentrations had increased by 7% (P less than 0.05) in all subjects. The increase was most marked in group B at 14% (P less than 0.05) compared to 3% in group A (ns). Apolipoprotein AI (apo AI) increased by about 7% in both groups (P less than 0.01). After 12 weeks HDL cholesterol and apo AI levels had almost returned to initial values. Measurements of HDL components showed increases of 6% to 12% in free cholesterol, cholesteryl ester (P less than 0.05), and phospholipid (P less than 0.01); whereas, the minor triglyceride fraction decreased by 20% (P less than 0.01). Zonal ultracentrifugation in four subjects revealed a preferential rise of about 35% in the HDL2 subfraction, increasing the HDL2/HDL3 ratio by about 20%. In parallel, the composition of the lipoprotein classes changed. The protein moiety of all classes, except low-density lipoprotein (LDL), expanded at the expense of the core components cholesteryl ester and triglyceride. Hepatic lipase (HL) activity decreased by 6% (P less than 0.05), and lipoprotein lipase (LPL) activity in adipose tissue increased by about 50% (P less than 0.05) during the first 6 weeks of training, while LPL activity in postheparin plasma and skeletal muscle did not change. The transient rise in HDL cholesterol levels was correlated (P less than 0.05) to the elevation of adipose tissue LPL activity. The alterations in HDL concentration were also related to changes in body composition and diet, especially to an increase in fat intake.

Adult↗
PubMed1983

Transcutaneous electrical nerve stimulation (TENS) as compared to placebo TENS for the relief of acute oro-facial pain.

The present paper describes the effect of high frequency, low frequency and placebo TENS on acute oro-facial pain in 62 patients, attending to an emergency clinic for dental surgery; they had all suffered pain for 1-4 days. The patients were randomly assigned to one of three groups receiving either high frequency (100 Hz), low frequency (2 Hz) or placebo TENS. In the two groups receiving TENS (42 patients) 16 patients reported a reduction in pain intensity exceeding 50%; out of these 16 patients, 4 patients reported complete relief of pain. In the placebo group (20 patients) 2 patients reported a pain reduction of more than 50%; out of these 2 patients, none reported a complete pain relief. Mechanical vibratory stimulation augmented the pain reduction obtained by TENS in 5 out of 10 patients.

Adult↗
PubMed1983

Experimental hyperthyroidism in man: effects on plasma lipoproteins, lipoprotein lipase and hepatic lipase.

We have studied the effects of triiodothyronine administration (20-40 micrograms three times daily over one week) in six healthy young men, on the activities of lipoprotein lipase and hepatic lipase and on plasma lipoprotein concentrations. Hepatic lipase activity in post-heparin plasma rose by 46 +/- 25% (p less than 0.025), whereas the activity of lipoprotein lipase did not change significantly. Plasma cholesterol concentrations decreased by about 20% (p less than 0.025), whereas there was no change in plasma triglyceride levels. The fall in plasma cholesterol could be accounted for by a reduction of HDL cholesterol (-11%, p less than 0.025) as well as LDL cholesterol (-27%, p less than 0.025). The data emphasize the role of hepatic lipase in the lipoprotein alterations associated with thyroid dysfunction.

Adult↗
PubMed1983

Acute effects of ethanol and its metabolites on plasma lipids and lipoprotein lipase activity.

The effects of ethanol, acetaldehyde, acetate and lactate on lipoprotein lipase (LPL) activity and regulation have been investigated. None of the substances had any direct effect on the enzyme or enzyme-substrate complex. Ethanol and acetate interfered with LPL regulation studied in vitro using rat adipose tissue. Acetate administration to humans did not influence the activity of LPL and hepatic lipase in post-heparin plasma, nor was the intravenous fat tolerance test affected. Ethanol administration markedly increased and prolonged the hyperlipidemia induced by oral triglyceride intake; the effect of acetate was much less pronounced. Thus, acetate does not seem to interfere with LPL regulation in man. The previously described impairment in LPL activity and regulation after ethanol intake is probably mediated by ethanol itself.

Acetates↗
PubMed1983

Relations between thyroid function, hepatic and lipoprotein lipase activities, and plasma lipoprotein concentrations.

Lipoprotein concentrations and activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were measured in 70 subjects with thyroid function ranging from overt hypothyroidism over subclinical hypothyroidism and euthyroidism to hyperthyroidism. In parallel with serum T3 (S-T3) concentrations increasing from low in hypothyroidism to high in hyperthyroidism there were gradually higher HL activities over the full spectrum of thyroid function, accompanied by decreasing levels of total and low density lipoprotein (LDL) cholesterol. High density lipoprotein (HDL) cholesterol was lower (P less than 0.05) in hyperthyroidism than in euthyroidism but not significantly changed in the hypothyroid groups. HL was correlated to S-T3 (r = 0.77, P less than 0.001), LDL cholesterol to log S-T3 (r = -0.76, P less than 0.001), and LDL cholesterol to log HL (r = -0.55, P less than 0.001). The activity of LPL was decreased (P less than 0.001) in overt hypothyroidism compared to euthyroidism but, in contrast to HL, the activity of LPL was not increased in hyperthyroidism. The plasma triglyceride (P-TG) concentration was elevated (P less than 0.01) in overt hypothyroidism but not significantly changed in subclinical hypothyroidism or in hyperthyroidism. The LPL activity was correlated to log S-T3 (r = 0.45, P less than 0.001), P-TG to log S-T3 (r = -0.37, P less than 0.01) and P-TG to log LPL activity (r = -0.71, P less than 0.001). Our results demonstrate that thyroid hormones influence HL and LPL activities in different ways, suggesting different mechanisms of action. Changes in HL activity seem to be an important mechanism for the disturbance of cholesterol metabolism in thyroid dysfunction while the thyroid hormone influence on LPL seems to be of importance mainly for the disturbance in triglyceride metabolism.

Adult↗
PubMed1982

Effects of conditioning vibratory stimulation on pain threshold of the human tooth.

The effect of mechanical vibratory stimulation on the human tooth pain threshold has been studied in 4 healthy naïve subjects. Vibration at 10 and 100 Hz was applied to a maxillary incisor and the electrical pain threshold was measured in an adjacent tooth. During the conditioning stimulation the pain threshold increased 1.2-1.8 times the unconditioned values. The present study indicates that mechanical vibratory stimulation applied to human teeth elevates the pain threshold in adjacent teeth.

Adult↗
PubMed1978

Neuroleptic-induced attenuation of brain stimulation reward in rats.

In 30-min free-operant tests, the dopamine receptor blockers pimozide (.125, .25, and .50 mg/kg) and (+)-butaclamol (.1, .2, and .4 mg/kg) attenuated lever pressing for lateral hypothalamic brain stimulation. When discrete self-stimulation trials were offered in a straight alleyway, pimozide increased start box latencies, slowed running speeds, and reduced lever-pressing rates. However, performance early in both lever-pressing and runway sessions was normal; performance deteriorated as testing progressed, following patterns that paralleled those seen when animals were tested with reductions in the amplitude of stimulating current. Spontaneous recovery was obtained in both situations; experimenter-imposed 10-min time-outs caused renewed lever pressing and running. In contrast, alpha-noradrenergic receptor blockade by phenoxybenzamine (5, 10, and 20 mg/kg) failed to produce extinction-like response patterns. These data support the view that central dopaminergic systems are important components of the neural mechanisms mediating reward.

Animals↗