The effect of splenectomy, produced chemically by means of ethylpalmitate, on the formation of heteroagglutinins in the rat]

The formation of heteroagglutinins against human O-erythrocytes was pursued in Wistar rats splenectomized "chemically" by means of intravenous injections of ethyl palmitite. Contrary to some data in literature the initial inhibition in the formation of antibodies was replaced by a significant titre increase ranging from the 8th to the 14th day following immunization. The tween 20 contained in the emulsion of ethyl palmitic did not influence the formation of heteroagglutinins. The examinations show that a possible use of palmitic ethyl for immunosuppression is questionable.     

The inhibitory effect of methyl palmitate on heteroagglutinin formation in rats.

In Wistar rats the immunosuppressive effect of methyl palmitate on the formation of heteroagglutinins against human O-group erythrocytes was followed. An i.v. injection of methyl palmitate both delayed the heteroagglutinin formation and decreased its intensity. The inhibitory effect of methyl palmitate was not accompained by the subsequent hyperactive phase as could be observed in the previous experiments using ethyl palmitate.     

Erythrocyte survival and haematocrit values in rats after i.v. application of ethyl palmitate and methyl palmitate emulsions

In the experiments on rats the effect of repeated application of ethyl palmitate emulsion (EP) and methyl palmitate emulsion (MP) on the survival rate of51Cr labelled erythrocytes and haematocrit values of the peripheral blood was studied. EP was applied in a total amount of 0.8 g, while MP due to its higher toxicity in a dose of 0.4 g per 100 g of body weight. The application of EP caused mild, though significant shortening of the survival period of the erythrocytes; the haematocrit values remained unchanged. Following application of MP no differences as compared to control animals could be found.     

The effect of intravenous injection of ethyl palmitate emulsion on sequestration of thermally damaged erythrocytes in rats with experimentally induced hypersplenism, and in normal rats.

The authors attempted at experimental elimination of sequestration function of the spleen in Wistar rats using an i.v. injection of ethyl palmitate emulsion, both in "hypersplenic" animals being long-term applied i.p. methyl cellulose solution, and in control rats. In the rats clearance of 51Cr-labelled and thermally damaged erythrocytes from blood was examined and their sequestration in the spleen and liver followed. The ethyl palmitate injection resulted in both experimental groups in a significant decrease of the erythrocyte counts sequestrated in the spleen, and significant prolongation of the elimination half time for thermally damaged erythrocytes from the blood.     

Interspecific comparison of ethyl methanesulfonate-induced mutation rates in relation to genome size.

A detailed presentation is made of the experimental data from the various systems used by Heddle and Athanasiou to conclude that “the relationship between mutation rate and genome size is as striking for EMS as it is for radiation, thus confirming the reality of the ABCW relation” and that “there is a relatively constant value of rec for all organisms.” It is noted that 2 of the 9 mutation rates cited came from seed treatments of higher plants and were not converted to haploid-genome mutation rates necessary for a valid comparison with other test systems. It is argued that the use of EMS-induced mutation rates from Drosophila and mouse post-meiotic male germ cells for comparisons with radiation-induced mutation rates from Drosophila and mouse spermatogonia is inappropriate. The paucity of the available data that was used is emphasized, and the dearth of all available data is recognized. The method of using the actual initially applied concentration of EMS alone as a measurement of “dose” is criticized. Nevertheless, when this procedure recommended by Heddle and Athanasiou as being necessary “to provide a consistent measure of dose” for inter-specific comparisons of EMS-induced mutation rates is applied, the papers from which the data they used were scrutinized, and other available mutation-rate data assessed, no evidence was found for a relationship between EMS-induced haploid-genome mutation rate and genome size in organisms from E. coli to H. vulgare that differ in DNA content by a factor of more than 1000. X-Ray-equivalent values differed by more than two orders of magnitude from one test system to another and by one order of magnitude for different male-germ cells of Drosophila. Our previous analysis of the available data for radiation-induced mutation rates found no relationship between mutation rate and genome size. It is considered that the failure to find a relation between EMS mutation rate and genome size from the type of analysis suggested by Heddle and Athanasiou has no bearing on the utility of the rec concept. Uncritical extrapolation from one chemical to another and to an X-ray equivalent of genetic damage has been forcefully criticized elsewhere.     

Hepatocytic ultrastructure in splenectomized rats treated with pregnenolone-16alpha-carbonitrile, a microsomal enzyme inducer.

Pregnenolone-16alpha-carbonitrile (PCN), given orally at the dose of 6.8 mg/100 g body wt, twice daily for 3 or 6 days, increased liver weight in intact rats, and reduced zoxazolamine paralysis in both unoperated and splenectomized animals. The steroid induced smooth endoplasmic reticulum proliferation in the hepatocytes of intact and splenectomized rats, while splenectomy alone caused rough endoplasmic reticulum fragmentation and vesiculation. It appears that the spleen does not influence the hepatic action of PCN.     

Partial and incomplete oxidation of palmitate by cultured beating cardiac cells from neonatal rats.

The discrepancy in the rate of [14C]O2 formation from either [1-14C]- or [16-14C]palmitate is demonstrated and could be explained by the preferential formation of L-(+)-3-hydroxybutyrate from the four carbon atoms at the omega terminus. The identity of this product as L(+)-3-hydroxybutyrate was established and shown to be the major component of the radioactive products in the extracellular medium from palmitate based on (a) ion-exchange chromatographical properties, (b) gas-liquid chromatography, (c) mass spectrometric analysis, (d) stereoisomeric separation, and (e) its very low rate of utilization by the cells. We therefore propose a shunt to the oxidation of palmitate in these cells occurring at the stage of L(+)-hydroxybutyryl-CoA which undergoes deacylation causing the product to be transported outside the cell.     

Protection of olfactory responses from inhibition by ethyl bromoacetate, diethylamine, and other chemically active odorants by certain esters and other compounds

Certain vaporous chemicals (chemically active odorants) arecapable of both stimulating olfactory responses and reactingwith receptors, ion channels, or receptor/ionophore macromoleculesto inhibit olfactory responses. We have studied the physiologicaleffects of several chemically active odorants using electrophysiologicaltechniques to record electroolfactogram (EOG) responses fromthe frog's olfactory mucosa. So far, the most studied agentsare ethyl bromoacetate (EBA), an alkylating agent, and diethylamine(DEA), a compound which is one of the strongest neutral organicbases. Certain odorants, or ‘protectants’, whenpresent before, during, and after exposure of the olfactorymucosa to either EBA or DEA have the property of maintainingolfactory responses which would otherwise be inhibited by exposureto the chemically active odorant alone. Protection from inhibitionby EBA is conferred by the presence of isoamyl acetate and afew closely-related esters, while protection from inhibitionby DEA is produced by the presence of p-dichlorobenzene. Protectionfrom inhibition by DEA is also achieved by lowering the pH ofthe olfactory mucosa through the simultaneous delivery of CO₂which produces carbonic acid. The mechanism of protection byesters and p-dichlorobenzene is unknown, but it seems likelythat these odorants somehow interfere with the access of thechemically active odorant to a site where it would normallyreact. ¹Present address: PSC Box 511, Peterson AFB, Colorado Springs,Colorado 80914, USA.²Permanent address: Department of Chemistry, New Mexico Instituteof Mining and Technology, Socorro, New Mexico 87801, USA.     

Selective inhibition of transition from sexual agglutination to zygote formation by ethyl N-phenylcarbamate in Saccharomyces cerevisiae

Effects of ethyl N-phenylcarbamate (EPC) on the mating reaction of Saccharomyces cerevisiae were studied, with special attention on the effect on the pheromone action. EPC inhibited zygote formation at a concentration which promoted induction of sexual agglutinability. EPC enhanced agglutinability induction by pheromone, but inhibited -pheromone-induced formation of large pearshaped cells in a mating type. The enhancement of agglutinability induction was accompanied with increased production of a agglutination substance and inhibition of pheromone inactivation. EPC arrested the cell cycle of a cells probably in the step controlled by CDC19, CDC35, cAMP etc., just before the step controlled by CDC28, pheromone etc.Abbreviations EPC Ethyl N-phenylcarbamate - PBS 0.01 M phosphate buffer solution, pH 5.5 - SPB spindle pole body     

The effect of myelopid on antibody formation in gamma-irradiated animals

The effect of a new immunocorrecting preparation, Myelopid, on the antibody-forming cell content of mouse spleen after gamma-irradiation (1-3 Gy) has been investigated. The preparation administered after immunization of mice with sheep erythrocytes increases the number of antibody-forming cells in the spleen, the effect being a function of radiation dose and time interval between the exposure and immunization. The preparation is ineffective when delivered after irradiation, but prior to immunization.