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K Larsson

Publications and source records attributed to K Larsson.

At least 307 records · Page 17Linked to original sources
PubMed1981

Effects of a new type of 5-HT receptor agonist on male rat sexual behavior.

8-Methoxy-2-(di-n-propylamino) tetralin (8-OMe-DPAT) and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) are two new drugs exerting selective actions on brain 5-HT neurotransmission. In the present experiments we have investigated the effects of these two drugs on male rat sexual behavior. It was found that both drugs reduce the number of intromissions preceding ejaculation and shorten the ejaculation latency. These effects are extremely pronounced and several animals ejaculate at the first intromission. In addition 8-OH-DPAT produced a slight reduction of the post-ejaculatory interval. There were no significant effects on latency to initiate copulation or in the number of mounts preceding ejaculation. Finally, sexual behavior was partly or completely restored in castrated male rats after injection with 8-OMe-DPAT or 8-OH-DPAT.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1981

Microbial adhesion to surfaces with different surface charges.

The adhesion behaviour of Streptococcus sanguis was studied on well-defined stearic and behenic acid multilayers which were prepared by depositing fatty acids on a solid substrate according to the Langmuir-Blodgett technique. Using this technique and by adjustment of the substrate pH it was possible to form outer surfaces consisting of either close-packed methyl or carboxyl end-groups. Thus adhesion was studied on non-polar surfaces formed by the methyl end-groups and on high density negatively charged surfaces formed by carboxyl groups. Under the experimental conditions the non-polar surfaces showed the same degree of adhesiveness as the reference (metal), whereas adhesion was completely inhibited on multilayers with a high negative surface charge. The significance of these results is discussed with regard to dental plaque formation.

Adhesiveness↗
PubMed1980

Stimulating effects of lisuride on masculine sexual behavior of rats.

Treatment of adult male rats with lisuride, an ergot derivative, resulted in selective changes in the masculine mating pattern. A dose-dependent decrease was found in the number of intromissions preceding ejaculation and in the ejaculatory latency. No other components of the mating pattern showed any significant alteration. Further, castrated sexually inexperienced rats treated with lisuride displayed a dose-dependent increase in complete heterosexual behavior.

Animals↗
PubMed1980

Gas chromatographic determination with flash methylation of palmitic acid in amniotic fluid in prediction of fetal lung maturity.

A new method for determination of palmitic acid in amniotic fluid was developed. The dipalmitoyl lecithin was hydrolysed, and after extraction the palmitic acid was flash methylated in the injector of the gas chromatograph. The between batch coefficient of variation was 6.0% at 40 and 70 mumol/l of palmitic acid concentrations in 500 microliters amniotic fluid. The accuracy of the method was demonstrated by linearity, recovery and correlation studies. The correlation coefficient was 0.98 between the new and bortrifluoride methylating method. The concentrations of lecithin and palmitic acid in amniotic fluid showed a correlation coefficient of 0.97. If the concentration of palmitic acid falls below 80 mumol/l respiration distress syndrome is likely. The new method was simple and easy to carry out and could be adjusted for haemoglobin contamination of the amniotic fluid. It was concluded that the determination of palmitic acid in amniotic fluid was a reliable method for the assessment of fetal lung maturity that could replace the determination of lecithin concentration.

Amniotic Fluid↗
PubMed1980

Exposure to solvent of tyrosyl and tryptophanyl residues of bovine antithrombin in the absence and presence of high-affinity and low-affinity heparin.

The exposure to solvent of the aromatic amino acid residues of free bovine antithrombin was probed by three different methods, which gave comparable results. Solvent perturbation suggested that about 35% of the tyrosyl residues and about 40% of the tryptophanyl residues of the protein are exposed to solvent. Fluorescence quenching experiments indicated that 60% of the tryptophanyl fluorescence of antithrombin arose from exposed residues. These values are similar to those previously reported for the human protein. In spectrophotometric titrations, two out of a total of ten tyrosyl residues titrated with a normal pKa and therefore, presumably are accessible to solvent. The binding of low-affinity of high-affinity heparin to antithrombin had neglibible effects on the solvent perturbation spectra and on the spectrophotometric titration curves. Iodide quenching experiments indicated an altered quenching pattern of the fluorescence of the protein in the presence of either form of heparin, but this effect could not be interpreted as a change of the exposure of trytophanyl residues. The binding of heparin to antithrombin therefore apparently leads to, at most, minimal changes of the exposure of the aromatic amino acids of the protein to the surrounding solvent.

Animals↗
PubMed1980

Further evidence for an inhibitory role of central 5-HT in male rat sexual behavior.

The 5-hydroxytryptamine (5-HT) reuptake inhibitors zimelidine (10 mg/kg IP 1.5h pretest) or alaproclate (20 mg/kg IP 1.5h pretest) produced a prolongation of the ejaculation latency and of the post-ejaculatory interval in male rats treated with a subthreshold dose of 5-hydroxytryptophan (5-htp) (12.5 mg/kg IP 1h pretest). The 5-HTP-induced (50 mg/kg IP 1h pretest) prolongation of ejaculatory latency was effectively counteracted by administration of the 5-HT receptor blocking agent metergoline (1 mg/kg IP 1.5h pretest). All animals were treated with an inhibitor of peripheral aromatic amino acid decarboxylase, indicating that the effects are of central origin. The results support the contention that central 5-HT plays an inhibitory role in male rat sexual behavior.

5-Hydroxytryptophan↗
PubMed1980

Distribution of small- and medium-sized molecules within the genital tract of artificially inseminated gilts.

Radiolabelled compounds of different molecular size were used as tracers mixed with seminal plasma to investigate whether seminal plasma enters the oviducts of inseminated gilts. The substances were 125I-labelled human serum albumin for 3 gilts, 131I-labelled polyvinylpyrrolidone plus 59Fe citrate in 2 gilts and 131I-labelled human serum albumin plus 59Fe citrate in 2 gilts. The gilts were slaughtered 1 h after insemination and the radioactivity was measured in 4 parts of the oviduct, 9 parts of the uterine horns, the body of the uterus and the cervix. Different quantities of the compounds used were found in all oviducts, but there was close agreement between the distributions of the two compounds in the genital tract after simultaneous insemination. There was a difference (60-80%) in total amount of recovered radioactivity between left and right uterine horns. It is concluded that all compounds used entered the oviducts regardless of their molecular sizes.

Animals↗
PubMed1980

Transuterine transport of small- and medium-sized molecules deposited in the uterus in gilts.

Radiolabelled compounds were mixed with seminal plasma and placed in the uterine lumen of anaesthetized gilts which were killed 5 min (N = 1) and 1 h (N = 2) later. After 1 h the distribution patterns of the 2 compounds placed in different horns were similar, indicating transuterine transport. Transuterine transport had begun by 5 min after deposition of seminal plasma. In all 3 gilts, the labelled substances had moved to the anterior segments of the oviduct.

Animals↗