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Biomedical subjects

H Kindahl

Publications and source records attributed to H Kindahl.

At least 235 records · Page 13Linked to original sources
PubMed1978

Release of prostaglandin F 2alpha during the bovine peripartal period.

Progesterone, estrone and 15-keto-13, 14-dihydro-PGF 2alpha levels were determined in the peripheral blood circulation during the peripartal period in 12 cows. Plasma concentrations of progesterone showed a gradual and continuous decrease during the last 60 days before parturition. This gradual decrease was followed by an abrupt decline in the progesterone concentration occurring 24-48 hours before delivery. The plasma levels of estrone started to increase about 30 days prior to parturition with high concentrations attained during the last days of pregnancy. After delivery the estrone content decreased to baseline levels. Increased levels of the PGF 2alpha metabolite were recorded 24-48 hours before parturition. These increased PGF 2alpha metabolite levels occurred before or in conjunction with prepartum luteolysis. Prostaglandin metabolite levels remained high during parturition and returned to baseline 10-20 days after delivery.

Animals↗
PubMed1978

Radioimmunoassay of prostaglandins and thromboxanes.

1. Decide on what organ or other biological material to study and select the proper compound for this study from the knowledge of precursor acid metabolism. Develop the RIA for this compound or a stable derivative thereof. 2. Whichever sample type is assayed (extracted or unextracted), the possibility of the presence of nonspecific interfering factors must be constantly kept in mind. Make dilution tests and assay for parallelism; however, do not accept parallelism as an absolute criterion of absence of nonspecific influence. 3. Use two or more completely different separation techniques for comparison when validating the RIA. 4. When evaluating the RIA, do not limit the investigation to the traditional reliability criteria: sensitivity, specificity, precision, and accuracy. The RIA may seem reliable at this stage and still give completely unrealistic values when applied to biological material. The method must be evaluated by other studies as well. 5. In the experimental design, aim at following the changes in prostaglandin levels in a series of samples instead of measuring absolute levels in single samples. 6. Make comparative studies employing different quantitative methods.

Animals↗
PubMed1977

Metabolism of thromboxane B2 in the cynomolgus monkey.

[5,6,8,9,11,12,14,15-3H8]-Thromboxane B2 was injected into the saphenous vein of female cynomolgus monkeys, and blood samples were withdrawn from the contralateral saphenous vein. The compound was eliminated from the circulation with a half-life of about 10 min after an initial rapid disappearance. Some more polar products appeared with time, and also small amounts of material less polar than thromboxane B2; however, the dominating compound in all blood samples was unconverted thromboxane B2. About 45% of the given dose of tritium was excreted into urine in 48 hrs. Several metabolites of thromboxane B2 were found. The major urinary metabolite was identified as dinorthromboxane B2 (about 32% of urinary radioactivity). Unconverted thromboxane B2 was also found in considerable amounts (13% of urinary radioactivity). It is concluded that 1) dehydrogenation at C-12 is not a major pathway in the degradation of this compound, in contrast to metabolism at the corresponding C-15 alcohol group of prostaglandins; 2) after having gained access to the circulation, thromboxane B2 is the main circulating compound; however, assay of thromboxane B2 in plasma will be complicated or precluded by large artifactual production of the compound by platelets during sample collection.

Animals↗
PubMed1976

Biosynthesis of prostaglandin F2alpha from arachidonic acid and prostaglandin endoperoxides in the uterus.

Formation of prostaglandin F2Alpha in the cow and guinea pig uterus microsomes was studied using 14C-labeled arachidonic acid and prostaglandin H2. The total conversion of arachidonic acid was of a low order and underwent fluctuations during the estrous cycle of the guinea pig, being highest towards the end of the cycle. Injections of beta-estradiol-3-benzoate also resulted in higher activity of the uterine prostaglandin synthetase. The uterine prostaglandin synthesizing system appeared to differ in several respects from that present in seminal vesicles, with regard to the proportions of the products formed and the effects of various agents, e.g. reduced glutathione. An inhibiting factor which supressed the fatty acid cyclo-oxygenase was found to be present in uterine preparations. Prostaglandin endoperoxide (prostaglandin H2) was very efficiently reduced to prostaglandin F2alpha by cow and guinea-pig uterus microsomes. Prostaglandin G2 also gave rise to prostaglandin F2alpha. Prostaglandin E2, on the other hand, was not reduced. Both the inhibiting factor and the endoperoxide reducing activity are likely to be parts of a highly specialized mechanism that modulates prostaglandin F2alpha formation in the uterus.

Animals↗
PubMed1976

Radioimmunoassay for urinary metabolites of prostaglandin F2alpha.

Antibodies against the main urinary metabolite of PGF2alpha in the human, 5alpha, 7alpha-dihydroxy-11-ketotetranorprosta-1,16-dioic acid, were raised in rabbits. The compound was coupled selectively in the omega position to bovine serum albumin prior to injection. The resuling antibodies did not distinguish between tetranor compounds varying only in structure at the omega carbon, and thus the assay could be used also for other metabolites of PGF2alpha, e.g. the main urinary metabolite in the guinea pig, 5alpha,7alpha-dihydroxy-11-ketotretranorporstanoic acid. Labeled ligands for the assays were prepared either in vivo by injection of [17, 18-3H]-PGF2alpha into humans after several days treatment with indomethacin, or in vitro by incubation of [17, 18-3H]-15-keto-13, 14-dihydro-PGF2alpha with mitochondria from rat liver. The sensitivity of the assay was 10 pg or 4 pg with these two preparations, respectively. The assay was employed for a number of measurements: normal daily excretion in a number of humans; excretion of urinary metabolites during treatment with prostaglandin synthetase inhibitors in human subjects, or after intravenous injection of PGF2alpha; excretion during human pregnancy; and prostaglandin production in the guinea pig during normal estrous cycles and pregnancies and after estrogen treatment. The results of these studies were in several cases compared to similar measurements earlier performed using mass spectrometric methods, and were found to agree well. Thus, this radioimmunoassay provides a simple and accurate method for estimating prostaglandin production, particularly suitable for long-term studies and for cases where repeated blood sampling must be avoided.

Animals↗
PubMed1976

A method for measuring the unstable thromboxane A2: radioimmunoassay of the derived mono-O-methyl-thromboxane B2.

A radioimmunoassay was developed for a mono-O-methyl derivative of thromboxane B2. The antibodies showed high specificity for this compound and cross reacted only 1.2% with thromboxane B2 and less than 0.1% with prostaglandins and prostaglandin metabolites. The method had a sensitivity of 7 picog. The radioimmunoassay was employed in studies where thromboxane A2 was generated in human platelets and immediately converted into mono-O-methyl thromboxane B2 by treatment of the sample with a large volume of methanol. In some of the experiments, thromboxane B2 was simultaneously measured by a separate radioimmunoassay. Using these two assays it was demonstrated that thromboxane A2 could be detected only during the earlier stages of the platelet aggregation, whereas thromboxane B2 rapidly reached a constant level. In a separate experiment, the half-life of thromboxane A2 in buffer was found to be 32.5 + 2.5 (S.D.) sec at 37 degrees C; the compound was more stable at lower temperatures. The t1/2 for thromboxane A2 was also considerably longer in plasma.

Antibody Specificity↗
PubMed1976

The release of prostaglandin F2alpha as reflected by 15-keto-13,14-dihydroprostaglandin F2alpha in the peripheral circulation during normal luteolysis in heifers.

Progesterone and the main plasma metabolite of PGF2alpha, 15-keto-13, 14-dihydro-PGF2alpha, were determined at hourly intervals in the peripheral circulation during luteolysis in two heifers. The prostaglandin release was found to occur during 2-3 days as rapid pulses with a duration of 1-5 hours prior to and during luteolysis, which was indicated by decreasing levels of progesterone.

Animals↗
PubMed1976

Radioimmunoassays for prostaglandin metabolites.

Radioimmunoassays were developed for the main plasma and urinary metabolites of PGF2alpha in the human, viz., 15-keto-13,14-dihydro-PGF2alpha and 5alpha, 7alpha-dihydroxy-11-ketotetranorprosta-1,16-dioic acid. The methods allowed assay of unextracted samples and had a sensitivity of 5 pg and 2 pg, respectively. The assays were evaluated by comparison with mass spectrometric data. Normal levels of these metabolites were estimated in a number of subjects. Levels in plasma and urine of the metabolites were followed after injection or during infusion of PGF2alpha and during administration of various antiinflammatory drugs.

Epitopes↗
PubMed1976

Prostaglandin levels in peripheral plasma during the reproductive cycle.

The levels of the major plasma metabolite of PGF2alpha, 15-keto-13,14-dihydro-PGF2alpha, were followed in peripheral venous plasma during the reproductive cycle in three species, viz., the ovine, bovine, and human species. In the sheep and cattle low levels were encountered during the major part of the estrous cycle. During the last days of the cycle high levels of the prostaglandin metabolite were found, coinciding with the decrease in progesterone production. The human menstrual cycle was characterized with respect to some plasma steroids and peptide hormones. The prostaglandin metabolite levels were low throughout the cycle, generally ranging between 30 and 70 pg/ml. No significant variation in the prostaglandin production could be seen during the menstrual cycle.

Animals↗