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Biomedical subjects

K Andersson

Publications and source records attributed to K Andersson.

At least 253 records · Page 14Linked to original sources
PubMed1987

Effects of acute continuous exposure of the rat to cigarette smoke on amine levels and utilization in discrete hypothalamic catecholamine nerve terminal systems and on neuroendocrine function.

The effects of acute continuous exposure to the smoke from 1-4 cigarettes have been studied in the male rat in terms of hypothalamic catecholamine levels and utilization as well as the secretion of anterior pituitary hormones. Catecholamine levels in discrete hypothalamic catecholamine nerve terminal systems were studied by quantitative histofluorimetry. Catecholamine utilization was studied by means of the tyrosine hydroxylase inhibition method using alpha-methyl-(+/-)-p-tyrosine methyl ester. The serum hormone levels of adenohypophyseal hormones and of corticosterone were measured by the use of radioimmunoassay procedures. The results show that acute continuous exposure to unfiltered but not to filtered (Cambridge glass fibre filters) cigarette smoke leads to small but dose-dependent reductions of amine levels in most of the hypothalamic noradrenaline and dopamine nerve terminal system. These effects were associated with an enhancement of regional hypothalamic noradrenaline utilization but not of dopamine utilization in the median eminence. Furthermore, a reduction of TSH and prolactin serum levels was noted as well as increases in ACTH secretion. These results are partly different from those previously obtained with rats acutely exposed to intermittent unfiltered cigarette smoke. This difference is suggested to be due to a temporary blockade of catecholamine release following acute continuous exposure to cigarette smoke.

Animals↗
PubMed1987

The importance of variations in questionnaire administration.

A standardised Nordic questionnaire for the analysis of musculoskeletal symptoms was administered to Swedish bus drivers and shunters in two different ways. The first was a cohort study in which all questions were focused on musculoskeletal troubles, whilst the other was the administration of the standardised questionnaire during a general health examination. Higher frequencies of musculoskeletal troubles were reported in the cohort study. When this type of questionnaire was administered prior to the general health examination, no differences were seen, which may be an effect of focusing first on the musculoskeletal symptoms. It can thus be concluded that it is important, not only to use standardised questionnaires, but also to consider the way the questionnaire is administered when comparing the results from different studies.

Journal Article↗
PubMed1987

Effective contraception with the levonorgestrel-releasing intrauterine device: 12-month report of a European multicenter study.

The use-effectiveness of an intrauterine contraceptive device releasing 20 mcg of levonorgestrel daily (Lng-IUD), and of a Nova T copper-releasing IUD, were studied in a randomized, comparative multicenter trial. The Lng-IUD was inserted in 1821, and the Nova T in 937 women. The 12-month net pregnancy rate with the Lng-IUD (0.1 per hundred women) was significantly lower than that with the Nova T (0.9 per hundred). Removal rates for menstrual problems and/or pain were similar for the two methods (net rates 7.5 and 8.7, respectively). The 12-month continuation rates were 82.2 for the Nova T and 79.7 for the Lng-IUD. The reduction of the bleeding led to oligomenorrhea and amenorrhea in users of the Lng-IUD; the removal rate for these reasons was 1.4. The removal rate for hormonal side effects with the Lng-IUD was 2.4. Blood hemoglobin concentrations increased among users of the Lng-IUD and decreased among users of the Nova T. The results show that the Lng-IUD was a highly effective contraceptive method which reduced menstrual bleeding. It is a promising alternative for women desiring a highly effective method for long-term use.

Adult↗
PubMed1987

Surface properties of lactobacilli isolated from the small intestine of pigs.

One hundred wild-type strains of the genus Lactobacillus were isolated from the small intestine of newly-slaughtered pigs up to 6 months of age. Cell surface hydrophobicity and capsule formation were studied on a number of strains. Strains showing high surface hydrophobicity as measured by the salt-aggregation test and hydrophobic interaction chromatography on Octyl Sepharose were commonly found to adhere in high numbers to isolated pig intestinal epithelial cells. Heat and protease treatment of bacteria of high surface hydrophobicity, including autoaggregating strains in phosphate-buffered saline, showed a drastic decline in this surface property. Three hydrophilic strains (LBp 1044, 1068 and 1073) also showed binding to intestinal cells but at a lower level (approx. 5 bacteria/cell) as compared with the best binding hydrophobic strain (LBp 1063, approx. 11 bacteria/cell). These findings suggest that different or multiple adhesion mechanisms may be involved in the colonization of the small intestinal mucosa of pigs. Cultures of selected strains grown in liquid media rich in carbohydrates did not affect their hydrophobic cell surface character. Therefore it seems less likely that carbohydrate capsule polymers are the major determinants of intestinal colonization of lactobacilli in pigs.

Animals↗
PubMed1987

Effects of subacute treatment with toluene on cerebrocortical alpha- and beta-adrenergic receptors in the rat. Evidence for an increased number and a reduced affinity of beta-adrenergic receptors.

Subacute treatment with toluene (80-1500 p.p.m.) produces a dose-dependent reduction of affinity and increase in density of the beta-adrenergic antagonist [3H]dihydroalprenolol binding sites in the frontoparietal cortex of the male rat, while the binding characteristics of alpha 1-adrenergic ([3H]WB 4101) and alpha 2-adrenergic ([3H]p-aminoclonidine) binding sites in the same region is unaffected by this treatment as evaluated in vitro. Therefore, it is suggested that the cortical beta-adrenergic receptors are particularly vulnerable to the action of toluene in vivo. It is speculated that as a result cortical beta-adrenergic neurotransmission may be altered following exposure to low concentrations of toluene, possibly related to the physico-chemical properties of toluene, leading to changes in membrane fluidity.

Animals↗
PubMed1987

Thyroidectomy and central catecholamine neurons of the male rat. Evidence for the existence of an inhibitory dopaminergic mechanism in the external layer of the median eminence and for a facilitatory noradrenergic mechanism in the paraventricular hypothalamic nucleus regulating TSH secretion.

Using the Falck-Hillarp methodology in combination with quantitative microfluorimetry, catecholamine (CA) levels and utilization in discrete hypothalamic CA nerve terminal systems in the male rat have been analyzed 24 h, 1, 2 and 4 weeks following thyroidectomy as well as after T3 or T4 restitution therapy 4 weeks after thyroidectomy. By means of high pressure liquid chromatography (HPLC), dopamine (DA) and noradrenaline (NA) levels and utilization 4 weeks after thyroidectomy have been analyzed in various brain regions. Triiodothyronine treatment (10 micrograms/kg, s.c., twice daily during 10 days) of 4-week athyroidic rats increased serum T3 levels, but not T4 serum levels. Thyroxine treatment (36 micrograms/kg, s.c., twice daily during 10 days) of 4-week athyroidic rats increased serum T4 levels and the T3 levels were found to be even slightly higher than those found in normal animals. Triiodothyronine or T4 restitution therapy reversed the changes induced by thyroidectomy on the anterior pituitary hormones (TSH, prolactin and growth hormone) and corticosterone secretion. It is suggested that removal of thyroid hormones may be responsible for the changes in the anterior pituitary hormones and corticosterone secretions. In the quantitative microfluorimetrical analysis 24 h, 1, 2 and 4 weeks after thyroidectomy, decreases in DA levels and utilization and increases in NA levels and utilization were found in the lateral palisade zone (LPZ) of the median eminence and in the parvocellular and magnocellular parts of the paraventricular hypothalamic nucleus (PA), respectively. In addition, 1-,2- and 4-week decreases were found in DA levels and turnover in the medial palisade zone (MPZ) as well as in NA turnover in the dorsomedial hypothalamic nucleus (DM) and in the 'border zone' (BZ) between the medial and lateral hypothalamus ventral to the fornix. In the HPLC analysis it could be demonstrated that 4 weeks after thyroidectomy decreases in DA levels and utilization in the mediobasal hypothalamus and increases in DA levels as well as NA levels and utilization in the hypothalamus had developed. The T3 or T4 restitution therapies after 4 weeks of thyroidectomy counteracted the effects on CA levels and utilization in all hypothalamic CA nerve terminal systems except for the reduced NA utilization found in the DM following 4 weeks after thyroidectomy.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Nicotine-induced increases in brain luteinizing hormone releasing hormone-like immunoreactivity and in serum luteinizing hormone levels of the male rat.

By means of radioimmunoassay procedures luteinizing hormone releasing hormone (LHRH)-, Metenkephalin- and somatostatin-like immunoreactivities have been measured in discrete hypothalamic and preoptic nuclei as well as serum luteinizing hormone (LH) levels. Nicotine (2 mg/kg, i.p.) produced after 5 min a significant and selective increase in LHRH-like immunoreactivity in the median eminence and in the medial preoptic nucleus, associated with increases in serum LH levels but without any changes in Met-enkephalin and somatostatin-like immunoreactivities in the median eminence. The results indicate that the nicotine-induced activation of LHRH-immunoreactive neurons involves an enhanced processing of the precursor peptide to LHRH.

Animals↗
PubMed1986

Increases in dopamine utilization in certain limbic dopamine terminal populations after a short period of intermittent exposure of male rats to cigarette smoke.

By means of a Walton smoke machine male rats were exposed to cigarette smoke from 1 to 4 cigarettes. Dopamine (DA) levels and utilization in the telencephalon were measured by quantitative histofluorimetry in discrete DA nerve terminal systems of the neostriatum, nucleus accumbens and tuberculum olfactorium. Exposure to unfiltered but not to filtered (Cambridge glass fibre filter) cigarette smoke resulted in a dose-dependent increase in DA utilization in the diffuse types of DA nerve terminal systems in the anterior nucleus accumbens and the lateral posterior tuberculum olfactorium. After exposure to the smoke from 4 cigarettes also an increase in DA utilization was observed in the dotted type (also cholecystokinin [CCK] positive) of DA nerve terminals of the nucleus accumbens (posterior part). The DA utilization in various parts of the neostriatum and in the dotted type of DA nerve terminals in the medial posterior tuberculum olfactorium were unaffected by acute intermittent exposure to cigarette smoke. The DA levels in the various DA nerve terminal systems in neostriatum, nucleus accumbens and tuberculum olfactorium were unaffected with the exception of the dotted and CCK positive type of DA nerve terminals of the nucleus accumbens, where a small reduction of the DA stores was shown following acute intermittent exposure to smoke from 4 cigarettes. The effects induced by exposure to the cigarette smoke in the limbic DA terminals were counteracted by mecamylamine pretreatment. It is suggested that the nicotine component of the cigarette smoke via activation of nicotinic cholinergic receptors can enhance DA release in discrete DA nerve terminal systems of the nucleus accumbens and tuberculum olfactorium. These actions may at least in part mediate the euphoria induced by inhalation of cigarette smoke.

Animals↗
PubMed1986

Pad tests in children with incontinence.

Different pad tests were compared in 50 incontinent children. In a 2-hour ward test with standardized activities and fluid provocation 70% were positive. In a simple 12-hour home test with 30 children 68% were positive; when a fluid provocation period was included in the home test with 20 children the frequency increased to 80%. Pad tests are easy to perform with children in the home and are valuable as screening instruments. Further, the simultaneous registration of events gives a more complete picture of the incontinence pattern.

Adolescent↗
PubMed1985

Effects of TRH and a rat TSH preparation on discrete hypothalamic and forebrain catecholamine nerve terminal networks in the hypophysectomized male rat.

A rat pituitary TSH preparation in doses of 10 and 100 micrograms/kg produced rapid and marked increases in dopamine (DA) levels and alpha-methyltyrosine-induced decline consistent with increased DA synthesis and release in the medial and lateral palisade zones (MPZ, LPZ) of the median eminence, and reduced noradrenaline (NA) turnover in the paraventricular hypothalamic nucleus (PA) of the hypophysectomized male rat. The TSH serum levels measured in these rats 2 h after the injection were within the physiological range after the injection of 10 micrograms/kg. TRH given intravenously in a dose of 100 micrograms/kg produced rapid and marked increases of DA release in the MPZ and LPZ of the median eminence and reduction of NA turnover in the PA of the hypophysectomized male rat. The TRH injection did not alter the serum levels of prolactin, TSH, T3 and T4. The results indicate that TRH-TSH-DA interactions take place in the local circuits in the median eminence thus supporting the view that a short and an ultrashort feedback action of rTSH and TRH respectively may exist in the median eminence. The rapid action of the rat TSH preparation as well as of TRH further supports this concept. The rat TSH preparation and TRH produced marked reductions in NA turnover in the PA. These results support the possibility that rat TSH and TRH may, via an action on the hypothalamus, influence the facilitatory noradrenergic mechanism operating at the soma-dendritic level of the TRH immunoreactive neurons projecting to the median eminence. Thus, the existence of a neuronal feedback loop from the medio-basal hypothalamus into the paraventricular hypothalamic nucleus is postulated.

Animals↗
PubMed1985

Isolation of bacterial plasmids by density gradient centrifugation in cesium trifluoroacetate (CsTFA) without the use of ethidium bromide.

Plasmids extracted from bacterial cells by alkaline extraction can easily be isolated from linear DNA by isopycnic centrifugation in CsTFA. This is a fast and simple method which circumvents the use of the intercalating dye, ethidium bromide, and consequently the problems associated with its removal. The buoyant densities for covalently closed circular DNA and linear DNA in CsTFA are 1.60 g/ml and 1.65 g/ml, respectively. The isolation is achieved regardless of plasmid size and can be accomplished at temperatures of between 4 and 30 degrees C. Plasmid DNA isolated in gradients of CsTFA are of a high purity and have been found to be intact when cleaved with restriction enzymes and ligated with T4 DNA ligase.

Centrifugation, Density Gradient↗
PubMed1985

Regression analysis of catecholamine utilization in discrete hypothalamic and forebrain regions of the male rat: effects of thyroidectomy.

The effects of thyroidectomy (4 weeks) on dopamine (DA) and noradrenaline (NA) turnover rates were determined by means of regression analysis. The disappearance of catecholamine (CA) fluorescence (using quantitative histofluorimetry) after tyrosine hydroxylase inhibition (alpha-methyl-DL-p-tyrosine methyl ester) has been investigated in discrete hypothalamic and forebrain DA and NA nerve terminal systems of the male rat. A time-dependent monophasic CA fluorescence disappearance was observed in all CA nerve terminal systems of the sham-operated and thyroidectomized rats. In the thyroidectomized rat, DA turnover in the anterior nucleus accumbens and in the medial and lateral palisade zones of the median eminence (ME) was reduced while DA turnover in the posterior nucleus accumbens was increased as compared to control rats. Furthermore, NA turnover was increased in the paraventricular hypothalamic nucleus (PA) and reduced in the dorsomedial hypothalamic nucleus (DM) and in the 'border zone' (lateral hypothalamus). Radioimmunoassay of hormones in serum demonstrated marked increases in TSH levels and reduced concentrations of GH, prolactin, corticosterone, triiodothyronine and thyroxine. The reduced DA turnover in the external layer of the ME and the increased NA turnover in the PA may indicate an inhibitory dopaminergic mechanism in the ME and a facilitatory noradrenergic mechanism in the PA in the regulation of TSH secretion. These mechanisms seem to interact with thyroid hormones. The reduced NA turnover demonstrated in the DM and in the border zone may be related to the lowering of growth hormone levels and pulsatility caused by thyroidectomy. Finally, the DA nerve terminal systems in the anterior and posterior parts of the nucleus accumbens are differently regulated by changes in the brain-pituitary-thyroid axis.

Animals↗
PubMed1985

Determinations of catecholamine half-lives and turnover rates in discrete catecholamine nerve terminal systems of the hypothalamus, the preoptic region and the forebrain by quantitative histofluorimetry.

To determine whether amine pool sizes, half-lives and turnover rates could be measured in discrete hypothalamic, preoptic and forebrain catecholamine (CA) nerve terminal networks by quantitative histofluorimetry, the CA fluorescence disappearance was studied at different time intervals after tyrosine hydroxylase inhibition. For comparison, the depletion of DA and NA following tyrosine hydroxylase inhibition in discrete brain regions was determined by high pressure liquid chromatography (HPLC). Following tyrosine hydroxylase inhibition using alpha-methyl-DL-p-tyrosine methyl ester, an apparently monophasic decline of the CA stores was demonstrated in all brain regions analysed both histochemically and by HPLC. A multiphasic DA disappearance was measured by HPLC in the peri- and paraventricular hypothalamic area. The DA nerve terminal networks generally had shorter half-lives than the NA nerve terminal networks. The shortest half-life (99 min) of the regions demonstrating a monophasic decline of CA stores was found in the CA nerve terminal system in the medial palisade zone of the median eminence. By the use of CA standards in the histochemically prepared sections, it was possible to convert the measured CA fluorescence into absolute amounts of catecholamines expressed in nmol X g-1 of tissue wet weight. It was shown that the CA stores and the turnover rates measured by quantitative histofluorimetry were 20-30 times greater than those measured using HPLC. The difference has been related to amine dilution with amine-poor areas in the specimens analysed by HPLC. By studying the accumulation of catecholamines after monoamine oxidase inhibition, it could be demonstrated that no concentration-dependent quenching of CA fluorescence occurred.

Animals↗