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Biomedical subjects

C E Olsen

Publications and source records attributed to C E Olsen.

106 records · Page 6Linked to original sources
PubMed1977

Prostaglandin regulation of macrophage collagenase production.

The production of collagenase (EC 3.4.24.3) by endotoxin-stimulated macrophages was significantly inhibited by indomethacin, indicating that prostaglandins (PGs) mediate this effect. Inhibitions of collagenase production by indomethacin was overcome by addition of exogenous PGE2 at 10 nM whereas the addition of 0.1 and 1.0 micrometer PGE2 increased the enzyme production to 3 times that achieved by endotoxin. Although the addition of prostaglandin alone to macrophage cultures did not stimulate collagenase production, the simultaneous addition of PGE1 or PGE2 and endotoxin enhanced collagenase activity 2- to 10-fold. This increase was detectable at PGE concentrations of 10 nM and was optimal at 0.1-1.0 micrometer. PGF2alpha had little effect on either the enhancement of collagenase production by endotoxin-stimulated macrophages or its restoration in cultures inhibited by indomethacin. Radioimmunoassay of prostaglandins in the culture media revealed that macrophages exposed to endotoxin secreted 40-fold more PGE2 than did unstimulated cells. The increase in PGE2 was detected 4 hr after exposure to endotoxin and was maximal at 14 hr. The peak PGE2 concentrations in the culture media were similar to those of exogenous PGE2 (about 10 nM) needed to restore collagenase production in indomethacin-treated cultures. These findings demonstrate the involvement of PGE in the endotoxin-activation of macrophages with resultant production of collagenase.

Cells, Cultured↗
PubMed1976

Chromatographic and functional comparison of human placenta and HeLa cell tyrosine transfer ribonucleic acids.

Chromatographic and functional properties of tyrosine isoaccepting transfer ribonucleic acids (tRNAs) from placenta and HeLa cells were analyzed and compared. RPC-5 chromatography separated four major isoacceptors from each source, with those from HeLa cells eluting generally later than those from placenta. There was some overlap: HeLa tRNA1Tyr eluted in a position between placenta tRNA3Tyr and tRNA4Tyr; and HeLa tRNA2Tyr and placenta tRNA4Tyr eluted in similar positions with the HeLa isoacceptor eluting slightly later than the placental isoacceptor. Thus there are no isoacceptors common to both sources. The function of the individual isoacceptors was compared in a rabbit-reticulocyte, cell-free, protein-synthesizing system for both the rate of incorporation of tyrosine into the polypeptide chain and the site of incorporation in alpha-globin. Two isoacceptors were compared simultaneously in the same reaction, and overlapping comparisons were made to relate each isoacceptor to all the others. There were no significant differences in the rates of incorporation among the isoacceptors, nor were there any differences in the sites of incorporation. All eight isoacceptors donated tyrosine equally well into the three tyrosine containing tryptic peptides of alpha-globin. Whatever the structural differences among the tyrosine isoacceptors are, they do not affect the function of the tRNA in this protein-synthesizing system.

Animals↗
PubMed1974

Prostaglandin F2alpha and oxytocin compared with hypertonic saline and oxytocin for the induction of second trimester abortion.

Second trimester abortion was induced in a randomized investigation using a single dose of prostaglandin F2alpha (PGF2alpha) in combination with oxytocin in one group of patients, and hypertonic saline (20%) in combination with oxytocin in another group of patients. Oxytocin was administered in order to induce a rapid abortion, and was given intravenously in a glucose drip (100 I.U. oxytocin added to 1 litre of 5% glucose). Administration rate was 10 I.U./hour. The PG-group consisted of 16 patients. The mean induction-abortion interval for this group was 14.2 hours, and all patients aborted within 24 hours. In three cases the bleeding exceeded 200 ml. In one of these cases infection occurred. Only mild side effects occurred. The saline group also consisted of 16 patients. The mean induction-abortion interval in this group was 21.5 hours. Eleven patients aborted within 24 hours. In two cases the bleeding exceeded 200 ml. No side effects occurred. Intraamniotic instillation of PGF2alpha seems to be a good alternative to hypertonic saline for termination of second trimester pregnancies.

Abortion, Induced↗
PubMed1966

[Heart arrest].

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Adult↗
PubMedDate not supplied

A new method for the synthesis of neoglycopeptides.

A new method for conjugation of small carbohydrates to peptides based on maleimido-thiol chemistry is described. The reducing carbohydrate is reacted with S-trityl-2-mercaptoethylamine in methanol. The resulting Schiff base is then stabilized by acetylation with acetic anhydride to give an S-trityl-protected glycosylamide. Activation of the carbohydrate is effected by brief treatment with trifluoroacetic acid/triisopropylsilane, followed by precipitation in ether. The thiol-functionalized carbohydrate is then reacted with a maleimido-modified peptide to give a neoglycopeptide. The potential of this method was investigated using maltose as the model compound. Furthermore, we prepared five maleimido-modified model peptides. In contrast to some literature reports, we found that the maleimido group is stable to treatment trifluoroacetic acid/triisopropylsilane which was used to cleave the modified peptides from the resin.

Acetylation↗
PubMedDate not supplied

Metabolism of thapsigargin in rat hepatocytes.

The cytotoxicity, uptake, and metabolism of thapsigargin, an inhibitor of the Ca(2+)-ATPases of the sarco- and endoplasmatic reticulum (the SERCA-family), were investigated in suspensions of rat hepatocytes using [3H]thapsigargin labeled at C-8. No effect was observed on the lactate dehydrogenase leakage from the cells or in glucose formation when hepatocytes were incubated with 0.5-25 microM thapsigargin. At 25 microM [3H]thapsigargin the initial rate of uptake into the cells was 471 nmol/10(8) cells/min. Thapsigargin metabolism followed first-order kinetics, with an initial rate of metabolism at 25 microM of 65 nmol/10(8) cells/min. The much faster uptake than metabolism suggests that thapsigargin probably is bound to cellular proteins or trapped in cellular membranes. The metabolites were characterized by normal and reversed phase TLC and by positive and negative FAB/ms. Two labeled products were identified when cells were incubated with 25 microM [3H]thapsigargin. The first product formed was desoctanoyl-thapsigargin, followed by formation of desacyl-thapsigargin. Thapsigargin metabolism was strongly inhibited by diethyl p-nitrophenyl phosphate, indicating that the deacylation of the compound is catalyzed by microsomal carboxylesterases. Upon prolonged incubation, a volatile, tritiated compound appeared, possibly water, due to oxidation of the alcohol group at C-8 of thapsigargin.

Animals↗