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Biomedical subjects

K Larsson

Publications and source records attributed to K Larsson.

At least 271 records · Page 15Linked to original sources
PubMed1985

Effects of maternal ethanol consumption on the offspring sensory-motor development, ultrasonic vocalization, audiogenic immobility reaction and brain monoamine synthesis.

Female rats were given 16% ethanol solution as the sole liquid during the entire period of gestation. At birth the offspring was removed and reared by foster dams consuming normal tap water. The development of sensory motor behaviour and emotional reactions was delayed by 1-2 days in the prenatally ethanol exposed pups as assessed by tests on body righting, acoustic startle response, air righting, rearing and ultrasonic vocalization. In the open-field test the normally occurring behavioural difference between the sexes was not found in the prenatally ethanol exposed pups. Both sexes of the ethanol exposed pups behaved like the female controls suggesting deficient masculinization of the ethanol exposed male pups during foetal age. Biochemical analysis of the brains showed a decreased synthesis of serotonin and dopamine.

Amino Acids↗
PubMed1985

Reduced beta 2-adrenoceptor responsiveness in exercise-induced asthma.

Beta-adrenoceptor responsiveness was studied both in vivo and in vitro in patients with exercise-induced asthma (EIA), asthmatic patients without EIA (NEIA), and control subjects. All subjects were age- and sex-matched and without medication at least one week prior to the tests. In vivo, beta-adrenoceptor responsiveness was evaluated by plasma concentration-effect studies for intravenously infused isoprenaline (0.02-0.1 micrograms X kg-1 X min-1). Mainly beta 2-adrenoceptor mediated responses to isoprenaline, ie, decreases in diastolic blood pressure and increases in plasma cyclic AMP, were reduced in EIA patients but not in NEIA patients. Heart rate and plasma glycerol responses to isoprenaline did not differ between the groups. In vitro, the beta 2-adrenoceptor mediated accumulation of cyclic AMP in lymphocytes stimulated by isoprenaline was attenuated (p less than 0.05) in EIA patients, whereas the beta 2-adrenoceptor responsiveness of lymphocytes from NEIA patients was normal. Thus, beta 2-adrenoceptor mediated responses were reduced both in vivo and in vitro in EIA patients, but not in NEIA patients. This finding that beta 2-adrenoceptor responsiveness was reduced only in a subgroup of asthmatic patients could explain some of the controversies in the literature concerning beta-adrenoceptor function in asthma.

Adolescent↗
PubMed1985

Studies of sympatho-adrenal reactivity and adrenoceptor function in bronchial asthma.

The aims of the present studies were to investigate sympatho-adrenal mechanisms and adrenergic receptor function in patients with bronchial asthma and healthy subjects. The patients were characterized with regard to the occurrence of exercise-, histamine- or allergen-induced bronchoconstriction in pre-trial tests. All medication was withdrawn during at least one week prior to the trials, in order to eliminate the influence of treatment. The patients were asymptomatic and had basal PEFR greater than 70% of predicted values prior to the trials. Healthy control subjects were matched with regard to sex and age. Alpha- and beta-adrenoceptor responsiveness were studied with improved in vivo-techniques, where different responses were related to plasma concentrations rather than doses of the agonists administered. Sympatho-adrenal reactivity, as assessed by plasma noradrenaline and adrenaline responses, to an orthostatic test and exercise was normal in asthmatic subjects. Surprisingly, there was no plasma catecholamines response to histamine- or allergen-induced bronchoconstriction. High plasma levels of noradrenaline and phenylephrine (by i.v. infusion) had little or no influence on bronchial tone, despite marked cardiovascular effects, in patients with exercise-induced asthma (EIA) or healthy subjects. Elevation of circulating noradrenaline failed to alter bronchial hyperreactivity to histamine in asthmatic patients. The blood pressure responses to infused noradrenaline and phenylephrine were similar in patients with EIA and healthy subjects, but the ensuing bradycardia was more pronounced in the EIA-patients indicating an increased baroreceptor sensitivity in these patients. High, but physiological, plasma levels of adrenaline dilated the airways with regard to end-expiratory flow rates but not Sgaw or PEFR. Furthermore, allergen-induced bronchoconstriction was counteracted by elevation of circulating adrenaline in patients with allergic asthma. These findings indicate that adrenaline may participate in the regulation of airway tone under physiological conditions. Beta 2-adrenoceptor sensitivity was found to be reduced in patients with EIA when assessed by both in vitro and in vivo techniques, while patients with non-exercise induced asthma did not differ from controls in this respect. Lymphocytes from EIA-patients had a reduced cAMP response to isoprenaline. Furthermore, the beta 2-mediated increase in plasma cAMP and the reduction of diastolic blood pressure in response to i.v. isoprenaline infusions were attenuated in the EIA-patients. These results do not seem to be influenced by previous anti-asthmatic drug treatment or the severity of the disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Glands↗
PubMed1985

Embryonic mortality in heifers after artificial insemination and embryo transfer: differences between virgin and repeat breeder heifers.

Embryos were collected from repeat breeder heifers and virgin heifers seven days after insemination, classified and transferred to the uterine horn contralateral to the corpus luteum of synchronised inseminated recipients. Altogether 35 transfers were performed, all reciprocally between repeat breeder heifers and virgin heifers. The recipients were slaughtered either 16 to 17 days or 32 to 35 days after insemination. The survival rate of the native embryos was lower among the repeat breeder heifers than among the virgin heifers both at 16 to 17 days (six of nine vs six of six) and at 32 to 35 days (three of 10 vs seven of 10) after insemination. A higher proportion of embryos transferred from repeat breeder heifers to virgin heifers than from virgin heifers to repeat breeder heifers survived to days 16 to 17 (five of six vs two of nine), while the same proportion of embryos survived to days 32 to 35 (two of 10) in both heifer categories. The results suggest that the uterine environment in repeat breeder heifers is suboptimal for the support of normal embryonic development.

Animals↗
PubMed1984

Failure to antagonize the 8-hydroxy-2-di-n-propylamino)tetralin-induced facilitation of male rat sexual behavior by the administration of 5-HT receptor antagonists.

The administration of the putative 5-hydroxytryptamine (5-HT) agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-hydroxytryptophan (5-HTP) produced a facilitation and an inhibition of male rat sexual behavior, respectively. The 5-HTP-induced inhibitory effects were at least partially antagonized by the administration of metergoline, methiothepine or pirenperone. However, none of these agents were able to counteract any facilitatory effects produced by 8-OH-DPAT. It is concluded that 8-OH-DPAT does not facilitate the expression of masculine sexual behavior in the rat by stimulation of 5-HT1 or 5-HT2 receptors.

5-Hydroxytryptophan↗
PubMed1984

Lisuride, LY-141865, and 8-OH-DPAT facilitate male rat sexual behavior via a non-dopaminergic mechanism.

In agreement with previous results from this laboratory, the ergot derivative lisuride (0.4 mg/kg IP) and the ergot congener 8-OH-DPAT (0.25 mg/kg IP) produced a marked facilitation of male rat sexual behavior. Furthermore, another ergot compound, the dopamine-2 selective agonist LY-141865 (2.5-20 mg/kg IP), was shown to facilitate male rat sexual behavior to the same degree. Neither the effects produced by LY-141865, nor the effects produced by lisuride or 8-OH-DPAT, were antagonized by pretreatment with the dopamine receptor blocking agent haloperidol, 0.16 mg/kg IP. A higher dose of haloperidol (0.32 mg IP), which produced clear extrapyramidal symptoms, was also ineffective in antagonizing the lisuride- or 8-OH-DPAT-induced facilitation of male rat sexual behavior. It is concluded that the stimulation of male rat sexual behavior produced by ergot and ergot-like drugs is mediated via a non-dopaminergic mechanism.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1984

Differential effects of a new serotoninomimetic drug, 8-OH-DPAT, on copulatory behavior and pelvic thrusting pattern in the male rat.

Treatment of sexually experienced male rats with 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a new drug having central serotoninomimetic activity, caused a dose-dependent decrease in the number of mounts and intromissions to ejaculation and shortened the ejaculation latency. These changes in the coital pattern were not accompanied by any marked changes in the organization of the thrusting pattern. It was concluded that treatment with 8-OH-DPAT may influence the excitability of the central neural circuits determining the elicitation of ejaculation without affecting those involved in the pelvic thrusting pattern, despite evidence of general motor disturbances.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1984

Development of sexual behavior in prenatally ethanol-exposed rats.

Female rats were given 16% ethanol solution as the sole liquid during the entire period of gestation. At birth the offspring was removed and reared by foster dams consuming normal drinking water. When tested for feminine sexual behavior in adulthood, the males showed marked signs of feminization as evidenced by an increased amount of lordosis responses. No changes were seen in the masculine sexual behavior. No deviations were seen in the female estrous cycles or in onset of vaginal estrus, whereas the onset of behavioral estrus was delayed. It is suggested that prenatal ethanol exposure may lower the fetal testosterone production and thereby interfere with the normal course of sexual differentiation in the male.

Animals↗
PubMed1984

Apomorphine and haloperidol-induced effects on male rat sexual behavior: no evidence for actions due to stimulation of central dopamine autoreceptors.

The administration of apomorphine (0.2-0.8 mg/kg IP) or (+)3-PPP(4-8 mg/kg IP) produced a facilitation of the male rat sexual behavior. Apomorphine in lower doses, as well as the selective DA autoreceptor agonist (-)3-PPP were ineffective. Except for a decrease in number of intromissions and an increase in the postejaculatory interval at the highest dose (0.32 mg/kg IP) there were no effects after administration of haloperidol. These data indicate that activation or inhibition of the presynaptic dopamine receptor does not affect male rat sexual behavior.

Animals↗
PubMed1983

The effect of medial preoptic-anterior hypothalamic lesions on testosterone plasma levels and testosterone conversion in the hypothalamus of male rats.

Male Wistar rats were submitted to bilateral high frequency lesions in the medial preoptic-anterior hypothalamic area or to sham procedure. The behavioral effect of the lesions was observed and plasma testosterone (T) and estradiol (E2) were measured by radioimmunoassay. In vitro metabolism of T was studied in the hypothalamus. Lesions produced a permanent deficit in male sexual behavior, an increase of plasma T and E2, and of hypothalamic T aromatization, and a decrease of T conversion to 5 alpha-dihydrotestosterone (DHT).

Animals↗
PubMed1983

A cubic protein-monoolein-water phase.

A cubic monoacylglycerol-protein-water phase has been identified by low-angle X-ray diffraction, and the main features of the ternary phase diagram monoolein/lysozyme/water are presented. The thermal stability of the protein in the lipid-protein cubic phase has been examined by differential scanning calorimetry. According to the physical properties of the phase it is proposed that the protein molecules are located in the water medium, i.e. in the water channel systems of the cubic structure earlier suggested. The ability of various proteins to form this cubic phase has been studied, and it was found that the formation of this phase is favoured by an isoelectric point (pI) far from pH 7 in a salt-free solution, thus by high electrostatic repulsive forces.

Calorimetry, Differential Scanning↗