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Biomedical subjects

K Larsson

Publications and source records attributed to K Larsson.

At least 343 records · Page 19Linked to original sources
PubMed1978

Comparison of light and electron microscopic determinations of the number of bacteria and algae in lake water.

Determinations of the number of microorganisms in lake water samples with the bright-field light microscope were performed using conventional counting chambers. Determinations with the fluorescence microscope were carried out after staining the organisms with acridine orange and filtering them onto Nuclepore filters. For transmission electron microscopy, a water sample was concentrated by centrifugation. The pellet was solidifed in agar, fixed, dehydrated, embedded in Epon, and cut into thin sections. The number and area of organism profiles per unit area of the sections were determined. The number of organisms per unit volume of the pellet was then calculated using stereological formulae. The corresponding number in the lake water was obtained from the ratio of volume of solidified pellet/volume of water sample. Control experiments with pure cultures of bacteria and algae showed good agreement between light and electron microscopic counts. This was also true for most lake water samples, but the electron microscopic preparations from some samples contained small vibrio-like bodies and ill-defined structures that made a precise comparison more difficult. Bacteria and small blue-green and green algae could not always be differentiated with the light microscope, but this was easily done by electron microscopy. Our results show that transmission electron microscopy can be used for checking light microscopic counts of microorganisms in lake water.

Journal Article↗
PubMed1978

On the agalactia post partum in the sow. A clinical study.

The purpose of the present investigation was to study the clinical symptoms of agalactic sows post partum in randomly selected swine herds. The study comprised 71 sows affected with agalactia post partum and 71 healthy sows from the same herds used as controls. Average morbidity of the disease in these 50 herds, consisting of an average of 25 sows, was 12.8%. Sixty-three per cent of the agalactic sows were affected within one day after farrowing. There was no difference in gestation length between healthy sows and agalactic sows. The body temperature was significantly higher for affected than for healthy sows. Mastitis was diagnosed in 35 out of 71 agalactic sows. The criteria for mastitis were swelling and herdening of one or several udder glands. Vaginal discharge was recorded for affected sows (55/57) as well as for healthy sows (51/58) and is therefore not significantly associated with agalactia. The temperament of the agalactic sows was moderately or severely affected in 62 out of 71 agalactic sows. Constipation was recorded for 13/59 agalactic sows and for 3/57 normal sows. The agalactic sows had significantly higher number of piglets per litter at birth while the litter size was higher for healthy sows at weaning. Numerically, more sows were culled among agalactic sows (16/48) than among normal sows (6/42). Moreover, sows affected with agalactia at the previous parturition were more inclined to meet with the disease at the next parturition. Further studies comprising large groups of animals are, however, necessary for evaluation of this question.

Animals↗
PubMed1977

Influence of some inflammatory or antiinflammatory substances on skin biopsies investigated with microcalorimetry and respiratory techniques.

Thermal effects were achieved from skin biopsies (epidermis, corium, subcutis) measured by batch-microcalorimetry, after exposure to potent inflammatory or antiinflammatory substances (compound 48/80, histamine, serotonine and hydrocortisone phosphate). Exothermic effects were achieved from 48-80, histamine and hydrocortisone phosphate, when exposed to the skin and lasting for varying time. From serotonine initial endothermic signals were achieved but after about 50 min there was stabilizing of the thermal reaction at the baseline. To analyze the nature of these non-specific thermal effects, determinations of O2 consumption and CO2 production were performed, using Warburg technique on exactly matched tissue pieces exposed to the same substances and run parallely with the microcalorimetrical determinations. An increased respiration, probably as an indicator of increased metabolism was registrated for all test substances acting on the skin. It felt, that the thermal effects reflect an increased metabolism of the tissue exposed to the test substances.

Basal Metabolism↗
PubMed1977

Thermal effects from degranulation of mastcells in cutaneous mastocytosis.

Small bipsies of the skin were taken from patients with papulo-cutaneous mastocytosis. The mast cell tumours were then degranulated with compound 48/80 (250 mug/ml in saline), and with a Sorption microcalorimeter, relatively strong exothermic reactions were measured, whereas normal skin showed only 1/10th the intensity. Disodium chromoglicate (1%) had no inhibitory effect on this thermal reaction.

Calorimetry↗
PubMed1977

Influence of maternal stress on offspring sexual behaviour.

During the last trimester of gestation, pregnant rats were exposed to crowded living conditions, or to immobilization combined with intense illumination. In adulthood, male offspring of mothers exposed to either condition of stress showed increased readiness to display feminine sexual behaviour (lordosis) while no deficits were observed in their masculine sexual behaviour. It was concluded that prenatal stress adversely affects sexual differentiation by causing a feminization but not a demasculinization of male offspring.

Animals↗
PubMed1977

Cholesteryl sulphate and phosphate in the solid state and in aqueous systems.

Cholesteryl sodium sulphate (CS) crystallizes as the dihydrate, the crystal structure of which is known. On heating the dihydrate, solid state phase transitions are observed at 65 degrees C and 95 degrees C and melting occurs at 165 degrees C. The structure of the high temperature phase has not been determined. Cholesteryl dihydrogen phosphate (CP) is not isostructural with any phases of CS. It undergoes a phase transition at 50 degrees C and melts at 190 degrees C. In systems with water CS is unstable whereas it was possible to determine the phase diagram of CP. In most of the composition range a crystalline hydrate is in equilibrium with a gel-phase. The latter has remarkable properties in that lamellar order exists with the 46 A lipid bilayer interleaved with water layers up to 1000 A. The monofilm behaviour of CS and CP at different pH levels is also reported.

Cholesterol↗
PubMed1977

In vitro conversion of 5-androstenediol to testosterone by the central nervous system and pituitary of the male rat.

The in vitro metabolism of 7-3H-5-androstenediol by the pituitary, some brain structures, and ventral prostate of adult castrated male rat was studied. Conversion of 5-androstenediol to radiochemically pure testosterone was demonstrated in all tissues studied in the presence of a NADPH generating system. Formation of dihydrotestosterone and dehydroepiandrosterone was also detected. The higher conversion rates were found in the pituitary, hypothalamus and mesencephalic tegmentum. These results demonstrate the presence of 3beta-hydroxy steroid oxidoreductase, delta4- delta5 isomerase, 5alpha-reductase, and 17beta-ol dehydrogenase in the rat brain which may in part explain the behavioral and brain virilization effects of 5-androstenediol.

Androstenediol↗
PubMed1977

Open field behavior and gross motor development in offspring of nursing rat mothers given penfluridol.

Nursing rat mothers were injected with penfluridol, a dopamine receptor blocking agent, at Day 1, 3, 5 and 7 after delivery, and their offspring were investigated at 6-18 days of age for various aspects of motor behavior development, and at 4, 8 and 12 weeks of age for open field behavior. No deficits were found in the development of locomotion, air righting, startle response and eye opening. Open field ambulation decreased from an abnormally high level at 4 weeks of age to an abnormally low level at 8 and 12 weeks of age. The ability to habituate to an open field decreased from a normal level at 4 weeks of age to an abnormally low level after 8 weeks of age. The behavior deficits were related to a decreased functional activity of the mesolimbic dopamine neuron system, and the possible relation to a clinical dysfunction among children - minimal brain dysfunction - was discussed.

Age Factors↗
PubMed1977

The development of a practicable method for deepfreezing of boar spermatozoa.

The present study was made in order to develop the freezing method of Crabo & Einarsson (1971) into a practicable deep-freezing method for boar spermatozoa. Semen was concentrated before dilution and a dosewise thawing procedure for the pellet-frozen semen was utilized. Two fertility tests on altogther 68 gilts were performed. In the first trial the insemination doses contained 6x10(9) spermatozoa and the dilution rate before cooling was 3:2 with a total dilution before freezing of 3:7. In the second trial the insemination doses contained 4.5x10(9) spermatozoa, primary dilution was 3:3 and final dilution 3:7. The pregnancy rate in trial 1 was 53% and in trial 2 72%. Mean litter size in pregnant gilts was 6.5 in trial 1 and 9.7 in trial 2. The difference in ratio of foetuses to c.l. in pregnant gilts between the trials was highly significant. The different dilution procedures are discussed and the lower fertility of semen frozen in trial 1 is suggested to be due to a shortened fertile life of spermatozoa so treated. The freezing method utilized in trial 2 is considered to be practically acceptable and the results are concluded to be satisfactory. A detailed description of the method and the equipment utilized can be requested from the authors.

Animals↗