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Biomedical subjects

K Larsson

Publications and source records attributed to K Larsson.

At least 379 records · Page 21Linked to original sources
PubMed1975

Lordosis behavior and mounting behavior in male rats: effects of castration and treatment with estradiol benzoate or testosterone propionate.

Male rats were selected for showing or not showing lordosis in response to manual stimulation. They were subsequently tested for mounting behavior with receptive females and for lordosis behavior in response to manual stimulation and to male mounting. Males showing lordosis as intacts displayed this behavior more readily following castration or castration and treatment with estradiol benzoate or testosterone propionate than males which did not show lordosis before castration. No group differences in mounting behavior could be detected under any of the endocrine conditions studied. It is suggested that the neural mechanisms mediated mounting and lordosis are dissociated and that individual differences in the occurrence of lordosis in male rats are due to differences in neural sensitivity to estrogen.

Animals↗
PubMed1975

Sexual impairment of inexperienced male rats following pre- and postpuberal olfactory bulbectomy.

Olfactory bulbectomy of sexually inexperienced male rats prevented the occurrence of sexual behavior in most of the operated animals. This effect was observed in rats bulbectomized before puberty as well as after puberty. Bulbectomized rats which had heterosexual experience prior to the operation did not deviate from intact rats. Males living in cohabition with intact males prior to the operation showed only minor deficits in their mating performances. It was concluded that the olfactory lobe while of only minor importance for maintenance of mating once sexual behavior has been initiated, plays an important role in initiation of sexual behavior of the male rat. Furthermore, since treatment with testosterone of prepuberally bulbectomized rats did not stimulate the animals to sexual activity it was concluded that the sexual impairment following bulbectomy of isolated males presumably is not due to an impaired production of gonadal secretions.

Age Factors↗
PubMed1975

Tilted hydrocarbon chains of dipalmitoyl lecithin become perpendicular to the bilayer before melting.

Differential scanning calorimetry studies of dipalmitoyl lecithin show two reversible transitions as the temperature is changed between 20 and 50 degrees C. A pretransition endotherm occurs at 35 degrees C prior to the main chain melting endotherm which occurs at 42 degrees C. X-ray diffraction studies show that below 33 degrees C the chains of the lecithin are fully extended, packed in a hexagonal crystalline lattice but tilted with respect to the plane of the bilayer. Between 35 and 42 degrees C the chains are similarly packed but oriented perpendicular to the bilayer plane. Above 44 degrees C the chains are "melted" or disordered. Monolayer studies of dipalmitoyl lecithin using continuous recording of pressure with molecular area reveal the existence of two solid condensed phases corresponding to these tilted and verticle chain structures. The tilted to perpendicular transition would account for the pretransition endotherm of the lipid; the crystalline to melted change corresponds to the larger transition observed at 42 degrees C.

Calorimetry↗
PubMed1975

Fertility and post-thawing characteristics of deep frozen boar spermatozoa.

Eight-nine gilts were inseminated with deep frozen boar spermatozoa thawed in seminal plasma, filtrate of seminal plasma, skimmed milk and isotonic glucose solution. The most favourable fertility results were obtained when seminal plasma was used as thawing diluent. It was shown that a relationship exists between the post thawing acrosome morphology, the post thawing GOT-release and the fertility of frozen spermatozoa.

Acrosome↗
PubMed1975

Antimicrobial effect of simple lipids and the effect of pH and positive ions.

Various branched fatty acids, particularly those of iso-configuration, have been shown to possess fungistatic and bacteriostatic properties. On the basis of their swelling effect on hyphae of Fusarium roseum it was suggested that this is due to an increase in the permeability of the plasma membrane. The solubilization of fatty acids in membranes should be expected to be influenced by the degree of dissociation and the presence of counter ions. Therefore, the effects of pH and K(+), Na(+), and Ca(2+) ions were studied. It is demonstrated that the presence of the univalent ions, Na(+) and K(+), markedly enhances the fungistatic effect of iso-tetradecanoic acid, whereas the opposite effect is noted for the divalent ion, Ca(2+). The effects are particularly pronounced at high pH. Furthermore, the antimicrobial effect obtained from the combination of fatty acid and tetramethylthiuramdisulfide is significantly enhanced in the presence of 0.1 and 0.2% KCl.

Anti-Infective Agents↗
PubMed1975

Antimicrobial effect of simple lipids with different branches at the methyl end group.

Various fatty acids of branched nature possess fungistatic and bacteriostatic properties. Some of these, particularly those of iso-configuration, strongly enhance the effect of conventional antimicrobial agents that act inside the cell membrane. A relation between this biological effect and the collapse properties of the corresponding monomolecular surface film on water has been observed. In this work, a series of fatty acids with a slightly smaller end group than iso-propyl, the omega-cyclopropane fatty acids, as well as one possessing a somewhat larger end group, the neo-branched fatty acids, have been examined. The omega-cyclopropane fatty acids were found to be more fungistatic than the iso-acids studied earlier. Furthermore, both cyclopropane and neo-fatty acids of short chain lengths exhibited synergistic effects in combination with tetramethylthiuramdisulfide.

Anti-Bacterial Agents↗
PubMed1975

Development of air righting in rats.

Rats aged between 13 and 18 days were dropped from different heights in order to establish the height at which 50% of the animals were able to perform complete air righting. The proportion of animals showing complete air righting abruptly increased at 16 days of age indicating maturation of the response at this age. No necessary relationship was observed between eye opening and air righting. At 15 days of age, when normally only a minority of the rats are able to display complete air righting, a marked effect of training was observed.

Age Factors↗
PubMed1975

[The effect of antibiotic supplementation on antibiotic resistance, transferable antibiotic resistance, morbidity, and growth in calves (author's transl)].

112 calves, divided into four groups, were given milk substitutes containing tetracycline (high-dosage feed), zinc bacitracin or Lactosat (control) and concentratesw with or without zinc bacitracin (Table I). We have investigated the incidence of antibiotic resistance and transferable antibiotic resistance in E. coli strains isolated from the faces of these calves and checked the growth and state of health in the four groups. Growth was also studies in a further ten feeding series comprising a total of 258 calves. Half this number received zinc bacitracin in milk substitute, the other half were fed milk substitute containing Lactosat, instead of antibiotics (Fig. 8). Tetracycline led to a quick increase of antibiotic-resistant straing (Fig. 4--6). This increase is significant in comparison with the other groups. Significant increases of resistance were also noted to ampicillin and chloramphenicol (Fig. 7), althoug these drugs were not used. A significant increase of the transferable resistance was also observed in the group of calves given tetracycline (Fig. 7) and to 65% at about 31/2 months after the end to 38% within 12 days (Fig. 7) and to 65% at about 31/2 months after the end of tetracycline feeding (Fig. 7). A marked increase of en-bloc transfer was also noted after completion of tetracycline feeding (Fig. 2). Up to slaughter, at the age of 6 months, no better growth was obtained with zinc-bacitracin supplement than with milk substitute without antibiotics but containing Lactosat. During the milking period the results varied between the different feeding series. In some series the mean growth in the zinc-bacitracin group was better than, in some no different from, and in other s poorer than that in the Lactosat group (TableII, Fig. 8). The only demonstrable positive effect of tetracycline supplement was a tendency twwards better health during the period of administration of the drug (Table II...

Ampicillin↗
PubMed1975

Prostaglandin induced parturition in swine with some aspects on prevention of the MMA (metritis, mastitis, agalactia) syndrome.

The effect of PGF2alpha to induce parturition in sows was studied in two herds. In one herd with a total number of 150 sows and with a good health status 12 sows were injected intramuscularly with 12.5 mg PGF2alpha during late pregnancy (110--114 days). During the same period 12 sows were treated intramuscularly with saline solution at corresponding gestation stage. The results are given in Tables I and II. The mean age calculated as number of litters was 2.6 in the experimental group and 4.3 in the control group. All sows treated with PGF2alpha farrowed within 30 hours after injection at an average time of 25.4 hours. The controls farrowed at an average 80.2 hours after injection. The mean farrowing time was 4.4 hours for the PG-treated sows while the corresponding figure for the controls was 6.6 hours. The litter size at birth, after 3 weeks and at weaning was somewhat higher in the experimental group. The same applies to the litter weight at the age of 3 weeks. The course of parturition was normal in all sows and the health condition during lactation was good. In another herd -- numbering 18 sows -- all sows which hade farrowed during the last 4 months before the present investigation, had developed the Mastitis-Metritis-Agalactia syndrome (MMA). The symptoms were a prolonged gestation length (116--117 days), fever, mastitis and agalactia. During the present study 3 sows were left untreated while 5 sows were given an intramuscular injection with 12.5 mg PGF2alpha during late pregnancy (112--114 days). Four of the five PG-treated sows farrowed within 32 hours, while the fifth sow farrowed 100 hours after injection. The sow not responding to the PG-treatment and the untreated sows all developed MMA while the four sows responding to treatment remained healthy. The gestation length in treated sows responding to treatment was 113--115 days. In the sows developing MMA the gestation length was 116--117 days. The potential effect for prevention of MMA of shortening the gestation length in this herd is discussed.

Animals↗
PubMed1975

Fractures of the tibial shaft after skiing and other accidents.

Fractures of the tibial shaft from skiing accidents were compared with fractures of other etiology. Skiing fractures more often affected the lower third of the tibia and they seldom were open. Many were comminuted or transverse but displacement tended to be slight. The incidence of complications was low and the periods of hospitalization, of healing, and of inability to work were shorter than for the other fractures. The highly favorable prognosis was evident whatever the method used for treatment. Methods of treatment of tibial fractures should not be compared on the basis of experience with skiing fractures, because of the exceedingly favorable prognosis of the latter.

Accidents, Occupational↗
PubMed1975

[Determination of progesterone in peripheral blood-plasma as a diagnostic aid in female swine (author's transl.)].

The determination of the peripheral plasma level of progesterone was evaluated as a clinical aid in the gynaecological diagnosis of female pigs. The normal cyclic variation of the peripheral plasma level of progesterone was determined in six cross bred gilts (Swedish Landrace times Swedish Yorkshire Breed) which were examined daily for the stages of oestrus. The results of this investigation are given in fig. 1. Peripheral plasma levels of progesterone were determined in 16 gilts with the clinical diagnosis of "silent heat". Despite all 16 gilts being sexually mature none of them had shown clinical signs of heat. The gilts belonged to 3 different farms, on all of which there was a high incidence of "silent heat". At least two blood samples were drawn 7 days apart from each of the gilts. Of the gilts examined 12 had variations in peripheral plasma level of progesterone. Of these 12 animals only 5 had clinical signs of heat, although the farmer had been advised, from the progesterone analysis, on the probable day of occurrence of heat. In 3 of the gilts, treatment with hormones (PMSCG) elicited the standing reflex when they were placed with a boar. In Table I is given some examples of the relationship of clinical signs of heat and the peripheral plasma level of progesterone. The peripheral plasma level of progesterone was also used as an early pregnancy diagnosis test in gilts. The gilts used in this investigation were all artificially inseminated with deep frozen boar semen. The expected pregnancy rate after insemination was 50%. Blood samples were drawn 17-25 days after insemination of 84 gilts. Peripheral plasma level of progesterone equal to or higher than 7.5 ng/ml were considered to indicate pregnancy. All gilts were slaughtered 4 weeks after the insemination and the number of fetuses were counted. A correct pregnancy diagnosis by the estimation of peripheral plasma level of progesterone was obtained in 95.2% of the gilts. The incorrect diagnoses were all false positives, viz. non-pregnant gilts were diagnosed as pregnant.

Animals↗