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Biomedical subjects

G Fredriksson

Publications and source records attributed to G Fredriksson.

36 records · Page 2Linked to original sources
PubMed1990

Levels of 15-ketodihydroprostaglandin F2 alpha during experimental Toxoplasma gondii infection in non-pregnant ewe lambs.

In order to study the relation between prostaglandin F2 alpha levels and fever during Toxoplasma gondii infection, six non-pregnant ewe lambs were exposed orally to T. gondii oocysts and an additional four animals were used as non-inoculated controls. Rectal temperature was measured daily during four weeks and plasma samples were analysed for the content of 15-ketodihydroprostaglandin F2 alpha. As compared to controls, the inoculated animals had significantly elevated rectal temperatures on days 4-16 after infection, but no concomitant changes in prostaglandin F2 alpha metabolite levels were recorded.

Animals↗
PubMed1990

Endotoxin concentrations in the blood following intravenous injection and effect on prostaglandin F2 alpha release, calcium and bile acids in goats.

Injection of endotoxin from Salmonella typhimurium in male goats resulted in a biphasic release pattern of PGF2 alpha, as determined by 15-ketodihydro-PGF2 alpha concentrations in plasma. A small initial peak at 30 minutes was followed by a second peak one hour after injection. The rectal temperature increased three to five hours after endotoxin injection and calcium concentrations started to decrease soon after injection; a significant decrease was seen from 105 minutes. Endotoxin concentrations varied among the animals but had a tendency to increase three hours after injection, simultaneously with a decrease in bile acid concentrations three hours after injection. The decrease in bile acids indicated alimentary stasis. Therefore, the raised endotoxin levels could be of endogenous origin. This study also shows that the prostaglandin metabolite is a very reliable parameter for estimating the effect of endotoxin.

Animals↗
PubMed1989

Bovine virus diarrhoea virus, a cause of early pregnancy failure in the cow.

In the present report attention is drawn to clinical and hormonal changes in heifers following experimental or natural infection with bovine virus diarrhoea virus in early pregnancy. Three heifers were infected experimentally and one naturally at pregnancy stages from 29-41 days. A leukopenia was seen 5-7 days after infection. All four animals experienced foetal death. Two of them aborted and in two the foetus was resorbed. Oestrus was observed at the expulsion of the foetus or in connection with vaginal discharge. Peripheral blood plasma levels of progesterone and the main blood plasma metabolite of prostaglandin F2 alpha (15-keto-13,14-dihydro-PGF2 alpha) were analysed. Diagnosis of pregnancy and embryonic/foetal viability were monitored by ultrasound. The interrelationship between infection and reproductive endocrinology is discussed and the importance of avoiding infection in early gestation is pointed out. It may easily pass unobserved and can thereby cause serious economic loss.

Abortion, Veterinary↗
PubMed1989

Influence of repeated prostaglandin F2 alpha injections on the ovarian function in the heifer.

This study was carried out in order to mimic the postpartum release of prostaglandins. Twenty-five mg PGF2 alpha was given intramuscularly three times daily from day 9 of the oestrous cycle during a period of 15 days in three heifers. Endocrine patterns related to ovulation and corpus luteum formation were determined. Blood samples were collected every second day during the cycle prior to treatment, before each injection during the treatment period and daily during the post-treatment cycle. Plasma samples were analysed for progesterone and oestradiol-17 beta. Palpation per rectum and realtime, B-mode ultrasound scanning of the reproductive tract were carried out once daily. During the period of treatment, ovulation occurred every time after the animals were in oestrus correlating with peaks of oestradiol-17 beta and with an inter-ovulatory interval of 6-7 days. No clear structure of a corpus luteum developed after these ovulations and progesterone levels remained low (less than 1 nmol/l) until the end of the treatment period.

Animals↗
PubMed1988

Electron-microscopic immunocytochemistry of 5-hydroxytryptamine in the ascidian endostyle.

The cellular and subcellular distribution of serotonin (5-hydroxytryptamine, 5-HT) in the endostyle of three species of ascidians, Ciona intestinalis, Corella parallelogramma, Ascidia mentula, was studied by light- (immunoperoxidase) and electron-microscopic (immunogold) immunocytochemistry. At the light-microscopic level 5-HT-like immunoreactivity (5-HT-LI) was exclusively found in cells located in the lateral portion of the endostyle, between zone 7, known to have iodinating capacity, and zone 8, which consists of ciliated cells. At the electron-microscopic level, the 5-HT-immunoreactive cells were found to correspond to cells containing polymorphous, dense granules, 100-300 nm in diameter. The granules were located in the supranuclear cytoplasm facing the endostyle lumen as well as in the infranuclear cytoplasm facing the extracellular space. Quantification showed that the 5-HT-LI was considerably higher (13-67 times) in cytoplasmic areas containing granules as compared to areas devoid of granules. Most, but not all, of the 5-HT-LI was associated with the dense core of the granules. In conclusion, serotonin-containing cells are located in the peripheral portion of the endostyle, between zones 7 and 8. Serotonin is stored in cytoplasmic granules that are present both in the apical and basal cytoplasm. This suggests the possibility that the cells are bipolar and secrete serotonin both in a basal direction to the extracellular space, and in an apical direction to the pharyngeal lumen.

Animals↗
PubMed1988

Iodine binding and peroxidase activity in the endostyle of Salpa fusiformis, Thalia democratica, Dolioletta gegenbauri and Doliolum nationalis (Tunicata, Thaliacea).

The protothyroid region in the endostyles of four species of tunicates was examined by means of autoradiography and cytochemistry, at both the light and electron-microscopic levels. To reveal the primary binding site for iodine, autoradiography was carried out on endostylar tissue from animals that had been incubated with high activity 125I over a short period of time. The specific iodine binding enzyme, a peroxidase, was traced by its reaction with DAB. In accordance with previous findings, the iodine-binding cells proved to be the same as those containing the peroxidase. There were also strong indications of a secondary uptake of iodinated compounds and subsequent release into the body fluid. Together with the ultrastructural features, the data provided strong evidence indicating that these cells constitute a protothyroid region, which partly functions as an endocrine organ, possibly homologous with the vertebrate thyroid gland. Since the number of zones varied between the species, the numeration of the protothyroid region also varied. However, in all the examined endostyles, the protothyroid region was seen to be situated dorsolaterally to the glandular regions of the endostyle concerned with food capture.

Animals↗
PubMed1987

Effect of bovine virus diarrhoea virus on pregnancy in the ewe monitored by ultrasound scanning and levels of 15-keto-13,14-dihydro-PGF2 alpha and progesterone.

Fourteen unvaccinated and seronegative ewes were experimentally infected with bovine virus diarrhoea virus around day 60 of pregnancy. Two other groups of pregnant ewes served as control animals. The animals were followed with ultrasound scanning to study the status of the fetus and with frequent blood sampling for analysis of progesterone and 15-keto-13,14-dihydro-PGF2 alpha, two hormones that could reflect the propagation of the infection. The unvaccinated ewes responded to the infection with abortion, resorption of the fetus, mummification or no changes at all. The endocrinological changes reflected in a most adequate way the pathological changes in the uterus. Detailed endocrinological studies can contribute to the understanding of the pathogenesis of some infectious diseases that affect reproduction.

Abortion, Veterinary↗
PubMed1987

Effect of Salmonella typhimurium endotoxin on PGF-2 alpha release and fetal death in the mare.

The infusion of Salmonella typhimurium endotoxin into pregnant mares resulted in a biphasic release pattern of PGF-2 alpha as determined by 15-keto-13,14-dihydro-PGF-2 alpha concentrations. The initial phase of 1 h duration was followed by accentuated release by 2 h after infusion; concentrations reached basal levels by 6 h. In 7 mares at 23, 26, 29, 33, 36, 53 and 55 days of gestation, fetal death occurred between 36 and 120 h after infusion; 12 mares at 46, 51, 56, 59, 65, 71, 73, 85, 103, 138, 283 and 318 days of gestation did not abort after endotoxin infusion. Luteal activity was compromised in all mares by 9 h after infusion. Progesterone concentrations were consistently lower in mares that aborted (1-2 ng/ml) than in those that did not abort. Mares therefore appear to be vulnerable to fetal loss by a clinical syndrome induced by Salmonella typhimurium endotoxin until about 50-60 days of gestation.

Animals↗
PubMed1986

Endotoxin-induced and prostaglandin-mediated effects on corpus luteum function in the mare.

Intravenous administration of endotoxin to mares causes synthesis and release of PGF(2alpha); this process affects corpus luteum function, either causing a transient drop in progesterone levels or complete luteolysis with shortening of the estrous cycle. It seems likely that any disease associated with endotoxemia can cause important prostaglandin-mediated effects on reproductive function in the mare.

Journal Article↗
PubMed1985

Ultrastructural demonstration of iodine binding and peroxidase activity in the endostyle of Oikopleura dioica (Appendicularia).

The endostyles of cephalochordates, ascidians, and larval petromyzontids have the capacity to organify iodine. A similar mechanism in the appendicularian endostyle has hitherto been unknown. Observations in this study of Oikopleura dioica with electron microscopic autoradiography and cytochemistry show that also the appendicularian endostyle has iodinating capacity and that the iodinating cells contain peroxidase, an enzyme responsible for iodination. After incubation in seawater containing 125I-, autoradiography revealed a selective labeling in the dorsal portion of the endostyle. The endostyle of O. dioica is on each side lined by four rows of corridor cells. The autoradiographic grains were mainly located over the endostylar lumen or associated with the luminal surface of the two central rows of corridor cells. These cells, but no other endostylar cells, also showed a positive reaction for peroxidase. The reaction product was distributed along the luminal plasma membrane and was also present in the cytoplasm within rough endoplasmatic reticulum, Golgi apparatus, and vesicles. The selective labeling as well as the cytochemical reaction were abolished by incubation in methimazole, an inhibitor of peroxidase. It is suggested that the two central rows of the corridor cells can be considered as homologs to iodine-binding zones in other endostyles and also as a primitive forerunner to the vertebrate thyroid gland.

Animals↗
PubMed1985

Release of PGF(2alpha) during parturition and the postpartum period in the ewe.

Peripheral plasma levels of 15-keto-13, 14-dihydro-PGF(2alpha) were determined from one week before parturition until five weeks postpartum in six ewes. Starting at approximately 1 nmol/l one week before parturition, the prostaglandin metabolite levels rose successively during the week preceding parturition and peaked at 70 to 125 nmol/l during parturition. During the first three days postpartum the concentrations of the 15-keto-13, 14-dihydro-PGF(2alpha) decreased to 0.5 to 1 nmol/l. These levels were maintained for three weeks and low levels of 50 to 100 pmol/l were reached around four weeks postpartum. The ewe, as well as other ruminants, has a sustained release of elevated concentrations of PGF(2alpha) postpartum. It seems likely that PGF(2alpha) plays a role in uterine involution.

Journal Article↗
PubMed1984

Iodine binding in the endostyle of larval Branchiostoma lanceolatum (Cephalochordata).

The asymmetrical endostyle of Branchiostoma larvae contains two different zones of mucus-producing cells which metamorphose to the paired zones 2 and 4 respectively in the endostyle of the adult. In both the larva and the adult these zones are parts of the food-trapping mechanism. An endostyle zone, which has a position corresponding to that of the paired iodinating zones in the endostyle of the adult, binds iodine selectively. The ultrastructure and labeling pattern indicate that the labeled cells in the larval endostyle belong to functionally different types. In one region of the iodinating zone iodine is mainly bound extracellularly at the apical cell surface. Also in the second region grains are located at the apical cell surface as well as over the cytoplasm and extracellularly at the basal plasma membrane. It is possible that iodination takes place in the lumen close to cells in the first region and that the labeled product is taken up and eventually released by cells of the second region. Our observations show that this primitive endostyle already has iodinating capacity and may synthesize and release thyroid hormones.

Animals↗