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Biomedical subjects

K Andersson

Publications and source records attributed to K Andersson.

At least 289 records · Page 16Linked to original sources
PubMed1983

Omeprazole provides protection against experimentally induced gastric mucosal lesions.

Omeprazole, given orally to rats, protects the gastric mucosa against various necrotizing agents, in doses (ED50 values 12-40 mumol/kg) which inhibit acid secretion. However, the protection is due to reduced acid secretion since omeprazole given intravenously in doses which completely inhibit acid secretion is not protective. The mechanism of the protective effect of omeprazole is unknown, but does not seem to be due to stimulation of the endogenous synthesis of prostaglandins since the effect was not blocked by indomethacin.

Animals↗
PubMed1983

Effects of chronic sino-aortic denervation in male rats on regional catecholamine levels and turnover and on neuroendocrine function.

A four week sino-aortic denervation produces an increase of adrenaline (A) turnover in the anterior but not the posterior hypothalamus and a selective reduction of dopamine stores in the anterior hypothalamus. Furthermore, the mean arterial blood pressure and heart rate are unchanged in conscious animals, and a selective increase in LH secretion is observed. The activation of a compensatory vasodepressor adrenergic mechanism in the anterior hypothalamus may in part be responsible for the maintenance of a normal mean arterial blood pressure after chronic sino-aortic denervation. The neurochemical changes in the hypothalamic area may also be related to the increase in LH secretion found after chronic sino-aortic denervation.

Animals↗
PubMed1983

Insect immunity. Attacins, a family of antibacterial proteins from Hyalophora cecropia.

Six closely related antibacterial proteins, attacins A-F, were isolated from the hemolymph of immunized pupae of the Cecropia moth, Hyalophora cecropia. Chromatofocusing separated attacins A-F, with isoelectric points between 5.7 and 8.3. Immunological experiments show that the attacins constitute antibacterially active forms of the previously isolated inducible immune protein P5. Their mol. wts., 20-23 K, are similar to that of protein P5, but significantly lower than 28 K found for preP5 synthesized in vitro (see accompanying paper). The six attacins can be divided into two groups according to their amino acid composition and amino-terminal sequences, attacins A-D constitute a basic group and attacins E and F an acidic one. Within each group the forms are very similar. The attacins efficiently killed Escherichia coli and two other Gram-negative bacteria isolated from the gut of a silk worm but they did not act on other Gram-positive and Gram-negative bacteria tested. Only growing cells of E. coli were attacked; cells suspended in phosphate buffer were inert. Besides the cecropins and lysozyme, the attacins represent a third class of antibacterial proteins in the humoral immune system of H. cecropia.

Amino Acid Sequence↗
PubMed1983

Chronic antidepressant treatment and central 5-HT synapses.

The present studies have shown that chronic antidepressant treatment with desipramine, imipramine, zimelidine and alaproclate led to adaptive changes in both pre- and postsynaptic 5-hydroxytryptamine (5-HT) receptor mechanisms which appear to result in 5-HT sub- or supersensitivity development depending upon the 5-HT nerve terminal systems analyzed. The results underline the heterogeneity of the central 5-HT neurone systems in their responses to chronic antidepressant treatment. An involvement of 5-HT comodulators is postulated in the actions of antidepressants on central 5-HT synapses. Finally, the results point to the importance of 5-HT neurone systems as targets for the action for antidepressant drugs and they may mediate at least some of the therapeutic activity of antidepressant drugs.

Animals↗
PubMed1983

Visualization of the formation and transport of a specific hnRNP particle.

The growth and maturation of the transcription products on the Balbiani ring (BR) genes in Chironomus tentans has been characterized by electron microscopy. The BR transcript is packed into a series of well defined ribonucleoprotein structures of increasing complexity: a 10 nm fiber, a 19 nm fiber, a 26 nm fiber, and a 50 nm granule. The basic 10 nm element was revealed in Miller spreads. The in situ structure of the transcription products and RNA compaction estimates suggested that the 10 nm fiber is packed into the 19 nm fiber as a tight coil. The transition of the 19 nm fiber into the 26 nm fiber is accompanied by a major change of the basic 10 nm fold into a noncoiled structure. Finally, the 26 nm fiber makes a one and one-third left-handed turn forming the final product, the BR granule. Upon translocation through the nuclear pore the BR granule becomes rod-shaped, which most likely corresponds to a relaxation of the highest-order structure into a straight 26 nm fiber.

Animals↗
PubMed1983

Effects of subacute treatment with toluene on central monoamine receptors in the rat. Reduced affinity in [3H]5-hydroxytryptamine binding sites and in [3H]spiperone binding sites linked to dopamine receptors.

Subacute treatment with toluene leads to a dose-related reduction of affinity in the [3H]spiperone binding sites labeling striatal dopamine (DA) receptors of the D2 type and cortical [3H]5-hydroxytryptamine (5-HT)-binding sites. It is suggested that these results represent a down regulation of activity at striatal DA and cortical 5-HT synapses, since they now may operate at higher concentrations of transmitters. The reduced affinity may be caused by the physicochemical properties of toluene leading to changes in membrane fluidity and thus in the regulation of DA and 5-HT receptors in the local circuits of the striatum and the dorsal cerebral cortex.

Animals↗
PubMed1983

Immobilization stress-induced changes in discrete hypothalamic catecholamine levels and turnover, their modulation by nicotine and relationship to neuroendocrine function.

Immobilization stress (1 h) induced discrete reductions in noradrenaline (NA) levels in the posterior periventricular hypothalamic region and in the paraventricular hypothalamic nucleus, and a decrease in dopamine (DA) turnover in the medial palisade zone (MPZ) of the median eminence, but failed to induce regional increases of hypothalamic NA turnover. Stress also stimulated the secretion of ACTH, corticosterone and prolactin, while vasopressin, LH and FSH serum levels were unaffected. The stress induced reduction of DA turnover in MPZ may mediate the stress induced increase of prolactin secretion. Nicotine (0.3 mg/kg, s.c., 1 h) did not by itself significantly influence catecholamine (CA) turnover in the various CA nerve terminal systems analyzed in the hypothalamus, but reduced NA levels in the subependymal layer (SEL) of the median eminence. Nicotine administration did not affect the serum levels of any of the hormones evaluated. Nicotine counteracted to a minor degree the immobilization stress-induced reduction in NA levels, and also the stress-induced secretion of ACTH, but not of prolactin suggesting the involvement of noradrenergic mechanisms possibly in the paraventricular nucleus in the nicotine modulation of stress induced increases of ACTH secretion. The nicotine-induced reduction of NA levels in SEL was blocked by stress as well as the tendency for nicotine induced increases of dopamine (DA) turnover in the medial and lateral palisade zones of the median eminence indicating opposing influences of immobilization stress and nicotine on at least some hypothalamic CA systems.

Adrenocorticotropic Hormone↗
PubMed1983

Intravenous injections of nicotine induce very rapid and discrete reductions of hypothalamic catecholamine levels associated with increases of ACTH, vasopressin and prolactin secretion.

The present findings show that nicotine given i.v. can within minutes induce increases of ACTH, vasopressin and prolactin secretion in the male rat, giving further evidence for the existence of nicotine-like cholinergic receptors involved in the regulation of these hormones. These changes were associated with rapid reductions of NA levels in the subependymal layer of the median eminence, in the nuc, dorsomedialis hypothalami and in the anterior and posterior periventricular hypothalamic area as revealed by quantitative microfluorimetrical measurements of CA fluorescence. Intraindividual correlations indicate the involvement of an inhibitory noradrenergic mechanism in the subependymal layer of the median eminence in the regulation of ACTH secretion, the involvement of noradrenergic mechanisms in the posterior periventricular area in the regulation of prolactin secretion and the involvement of dopaminergic mechanisms in the medial palisade zone of the median eminence in the regulation of prolactin secretion. A rapid rise of prolactin secretion seems to be associated mainly with a reduction of NA levels in the posterior periventricular area indicating the existence of a possible facilitatory noradrenergic mechanism in this region regulating prolactin secretion.

Adrenocorticotropic Hormone↗
PubMed1983

Monoclonal antibodies to cholera toxin with special reference to cross-reactions with Escherichia coli heat-labile enterotoxin.

Seventy monoclonal antibodies to cholera toxin were prepared and characterized. All were of immunoglobulin G (IgG) isotypes (39 IgG1, 29 IgG2, and 2 IgG3). A total of 61 clones produced antibody directed against the B subunit, and 9 clones produced antibodies with specificity for the cholera toxin A subunit. Among both the anti-B and anti-A antibodies, there were representatives which showed full cross-reactivity with the heat-labile enterotoxin of Escherichia coli (14 clones), others which gave partial cross-reactions (12), and still others (44) which did not cross-react. Although 24 of 25 tested anti-B monoclonal antibodies could neutralize cholera toxin, none of the 9 anti-A clones had any detectable neutralizing ability. Among the anti-B antibodies, those which cross-reacted completely with E. coli heat-labile enterotoxin all had strong cholera toxin-neutralizing capacity, whereas those with lesser or no degree of cross-reactivity varied more in their neutralizing potency. The isolation of monoclonal antibodies that distinguish between enterotoxins of different bacterial origin suggests the possibility of developing immunodiagnostic methods allowing species-specific enterotoxin detection in stools of patients with diarrheal disease.

Antibodies, Monoclonal↗
PubMed1983

Monitoring 1,6-hexamethylene diisocyanate in air by chemosorption sampling.

Monitoring 1,6-hexamethylene diisocyanate in air by chemosorption sampling. Scand j work environ health 9 (1983) 497-503. A sampling procedure for 1,6-hexamethylene diisocynate (HDI) in air is described. The diisocyanate is trapped on a chemosorption tube containing 9-(N-methylaminomethyl)anthracene adsorbed on Amberlite XAD-2. Recoveries in the laboratory experiments were 81-91%. The chemosorption technique was evaluated in the field by measurements at two different factories using HDI as a hardener in two-component paints for vehicle refinishing. Simultaneous sampling with a fritted-glass bubbler and by the chemosorption technique showed equal collection efficiencies for HDI when 3.5- to 22-1 air samples were used. For air samples exceeding 20 1 the collection efficiency of the fritted-glass bubbler decreased. Several additional peaks appeared in the chromatograms from the fritted-glass bubblers. Statistical treatment of the data showed that these peaks are closely related to the amount of HDI.

Air Pollutants, Occupational↗
PubMed1983

Increased amine turnover in several hypothalamic noradrenaline nerve terminal systems and changes in prolactin secretion in the male rat by exposure to various concentrations of toluene.

Subacute exposure of rats to varying concentrations of toluene vapours leads to increases of amine levels and turnover in several types of hypothalamic noradrenaline nerve terminal systems. Furthermore, the exposure of toluene in concentrations ranging from 80-3000 ppm and benzene (1500 ppm) produced differential effects on dopamine and noradrenaline turnover within various parts of the hypothalamus. These regions are involved in neuroendocrine regulation and disturbances in the secretion of prolactin were demonstrated after exposure to toluene.

Animals↗
PubMed1982

Vasopressor effects of substance P and C-terminal sequences after intracisternal injection to alpha-chloralose-anaesthetized rats: blockade by a substance P antagonist.

Substance P (SP) and the C-terminal sequences octa- and penta-SP produced dose-dependent vasopressor responses, and the action was associated with mild tachycardia. The vasopressor effect of SP was counteracted by the SP antagonist [D-Pro2,D-Phe7,D-Trp9]SP given intracisternally, suggesting that central SP receptors were involved. Experiments with different sodium contents in the vehicle and with naloxone pretreatment indicate that central naloxone-sensitive opiate receptors may exist, capable of modulating the effects of SP receptor activation.

Amino Acid Sequence↗
PubMed1982

Selective reduction of adrenaline turnover in the dorsal midline area of the caudal medulla oblongata and increase of hypothalamic adrenaline levels in the Lyon strain of genetically hypertensive rats.

Catecholamine levels and turnover have been studied in 5 week old male genetically hypertensive (LH) and normotensive (LN) rats of the Sprague-Dawley Lyon strain. The results demonstrate increased hypothalamic adrenaline levels and a reduced adrenaline turnover in the dorsal midline of the medulla oblongata (DCMO) in the LH rats compared with LN control rats. The reduction of adrenaline turnover in the DCMO may contribute to the development of spontaneous hypertension.

Animals↗
PubMed1982

Rapid reformation of the thick chromosome fiber upon completion of RNA synthesis at the Balbiani ring genes in Chironomus tentans.

We have studied the ultrastructure of the Balbiani ring genes in Chironomus tentans during treatment with the RNA synthesis inhibitor DRB (5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole). This nucleoside analogue blocks transcription at or near the initiation site but does not interfere with the elongation and termination processes. In the ordinary active state the Balbiani ring genes display a 5 nm chromosome fiber, carrying densely distributed, growing ribonucleoprotein particles (Andersson et al., 1980). When the transcriptional activity declines, a 10 nm fiber can be observed between sparsely distributed RNA polymerases. Furthermore, after passage of the last RNA polymerase the 10 nm fiber can be seen as well as its gradual packing into a 25 nm thick fiber. Thus, the active chromosome fiber is rapidly packed into higher order structures when the fiber is not directly involved in transcription. The formation of the thick fiber does not require that the gene along its entire length is devoid of active RNA polymerases. The thick fiber can again be mobilized for transcription, since in reversion experiments the BR genes appear as ordinary active genes with an extended nucleofilament and densely packed nascent transcription products. The dynamic behaviour of the chromosome fiber during transcription is discussed as well as the packing and unpacking of a gene into higher order structures.

Animals↗
PubMed1982

Interactions of nicotine and pentobarbitone in the regulation of telencephalic and hypothalamic catecholamine levels and turnover and of adenohypophyseal hormone secretion in the normal male rat.

The effects of single intraperitoneal injections of nicotine (1 mg/kg) and the sedative-hypnotic drug pentobarbitone (30 mg/kg) alone or in combination have been studied on catecholamine (CA) nerve terminal system of the hypothalamus and the forebrain and on the adenohypophyseal hormone secretion of the normal male rat. Nicotine produced discrete reductions of dopamine (DA) levels and increases of DA turnover in striatal and limbic areas of the forebrain and increases of amine turnover in different hypothalamic noradrenaline (NA) nerve terminal systems. These effects were all antagonized by simultaneous treatment with pentobarbitone. Pentobarbitone alone, however, did not modulate CA levels or turnover in the various parts of the hypothalamus and forebrain analyzed. On the other hand, pentobarbitone increased GH and prolactin secretion and in association with tyrosine hydroxylase inhibition markedly reduced corticosterone secretion. These effects were partly counteracted by nicotine in the case of GH and prolactin secretion. Furthermore, a positive interaction appears to exist between nicotine and pentobarbitone in their actions on LH secretion. The results suggest that pentobarbitone can antagonize the actions of nicotine on CA levels and turnover in various CA nerve terminal systems of the brain leading to possible reductions in nicotine induced arousal and positive reinforcement. The neuroendocrine actions of pentobarbitone do not seem to be greatly modulated through nicotinic cholinergic receptors.

Animals↗
PubMed1982

Toluene and telencephalic dopamine: selective reduction of amine turnover in discrete DA nerve terminal systems of the anterior caudate nucleus by low concentrations of toluene.

The present study demonstrates reductions of dopamine (DA) turnover in various areas of the anterior nucleus caudate of rat by toluene at concentrations lower than the current OSHA threshold limit value (100 ppm). Thus, toluene at low concentrations may produce disturbances in dopaminergic mechanisms of the basal ganglia probably leading to functional changes in sensory-motor integration. The increases in DA turnover in the cholecystokinin (CCK)-DA terminals of the subcortical limbic system induced by high concentrations of toluene may be part of the neurochemical basis for its abuse as a euphoric agent in man.

Animals↗