Lipid characterization and14C-acetate metabolism in catfish taste epithelium

Summary The catfish,Ictalurus punctatus is an important model system for the study of the biochemical mechanisms of taste reception. A detailed lipid analysis of epithelial tissue from the taste organ (barbel) of the catfish has been performed. Polar lipids account for 62±1% of the total, neutrals for 38±1%. Phosphatidyl-cholines, serines and ethanolamines are the major constitutents of the polar fraction. Plasmalogen concentration is high relative to that of non-neural tissues. [¹⁴C]-Acetate is incorporated into cell lipid fractions after incubation of barbel tissue at 37°C for 60 min. Percentage amounts of most lipids change with time during this in vitro incubation. The phospholipids are the most metabolically active fractions. This work yields information for continuing reconstitution experiments and indicates that the taste epithelium of this important model system is a metabolically active tissue capable of supporting lipid turnover/synthesis.This work was supported in part by NIH Research Grant No. NS-23622, NS-22620, and by the Veterans Administration.     

The distribution of carcinogens, 4-nitroquinoline-1-oxide and 4-hydroxyaminoquinoline-1-oxide,in the nervous system and its possible neurotoxicological significance

Summary 4-NQO-¹⁴C can enter the grey matter parenchyma of the central nervous system of mice after i.v. injection. The level of its uptake by the central grey is higher than that taken up by the central white and by the trigeminal and spinal dorsal root ganglia. This pattern of distribution is strikingly different from that obtained after i.v. injection of 4-HAQO-¹⁴C, suggesting the possible occurrence of 4-NQO encephalomyelopathy having entirely different sites of lesions from those of 4-HAQO neuropathy.This work was supported by a grant-in-Aid for Special Project Research from the Ministry of Education, Science and Culture of the Japanese Government (No. 321304, 1978).     

Cytoplasmic14C-labeled arginine basic proteins of Ehrlich ascites tumour cells

Summary With the use of¹⁴C-arginine it is shown that among soluble cytoplasmic proteins of Ehrlich ascites tumour cells there appear basic proteins rich in arginine with the content of amino acid higher than 14%. The amount of these proteins is about 10%. The role of arginine-rich basic proteins in the cytoplasma is briefly discussed.Supported by Polish National Cancer Programe PRC Project No. 1318/13. The authors are grateful to Mrs Anna Zbroch and Elzbieta Lipczyska for skillful technical assistance, during the course of this work.     

Elimination and metabolism of dimethylnitrosamine (DMN) byXenopus laevis and other amphibians

Summary The elimination of (¹⁴C)-DMN after i.p. injection intoXenopus was measured, as was the metabolism in vitro of (¹⁴C)-DMN by liver fromXenopus and 9 other amphibian species. In view of its rapid elimination from the body and low rate of metabolism byXenopus liver in vitro, DMN is unlikely to be toxic or carcinogenic inXenopus.This work was supported by a grant from the Cancer Research Campaign. We are also grateful to Dr P. F. Swann, both for the supply of DMN and DEN and for many useful discussions.     

Influence of 2-methyl-2-(p-1,2,3,4-tetrahydro-1-naphthylphenoxy)propionic acid on the oxidation of cholesterol by rat liver mitochondria

Zusammenfassung Es wird gezeigt, dass bei männlichen Wistar-Ratten im 3-Wochen-Diätexperiment mit Zusatz von 0,3% 2-Methyl-2-(p-1,2,3,4-Tetrahydro-1-naphthylphenoxy)-Propionsäure (Su-13437) die Oxydation von 26-¹⁴C-Cholesterin zu¹⁴CO₂ durch Lebermitochondrien (bezogen auf mg/N) ähnlich wie bei den Kontrollen war. Bei den Versuchstieren war jedoch bei Abwesenheit von Cytosol im System die Oxydation durch Lebermitochondrien erhöht.

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Acknowledgment. This work was supported, in part, by a grant No. HE-03299 and a Research Career Award No. 4-K6-HE-0734 from the National Heart Institute, N.I.H. We are indebted to Dr. W. I.Taylor, CIBA Pharmaceutical Co., Summit, N.J., for the generous gift of Su-13,437.     

A microbial metabolite of TCDD

Summary In the present study we describe the occurrence of a metabolite of TCDD, which arose in several microbial cultures after long term incubation. The polar metabolite amounted approximately 1% of the input material, and was found to be a hydroxylated derivative of TCDD.The work was supported by a grant from the Swiss Federal Government to R.H. and M.P. We thank Dr K. Grob, GC-Laboratory ETH Zürich, Dübendorf, Switzerland, for providing the highly inert column used in this work, and H.-R. Buser, Swiss Federal Research Station, Wädenswil, Switzerland, for his help in the analysis of the¹⁴C-TCDD.     

Insect tissues,not microorganisms,produce linoleic acid in the house cricket and the American cockroach

Summary Biosynthesis of linoleic acid, 182(n–6), was unambiguously demonstrated to occur in the cockroach,Periplaneta americana, and the cricket,Acheta domesticus. Axenic tissue from both of these insect species was demonstrated by radio-gas-liquid chromatography (radio-GLC) and radio-high-performance liquid chromatography (radio-HPLC) to incorporate [1-¹⁴C]acetate and [1-¹⁴C]oleate into this essential fatty acid.This work was supported by the National Science Foundation under grant DCB-8914417. We would like to thank Coby Schal for his generous gift of American cockroaches and Tania Kellermeyer for her excellent technical assistance.     

The formation of disulfide bonds in human protamines during sperm maturation

Summary The disulfide contents of human sperm heads, as measured by reduction to the sulfhydryls and subsequent alkylation with¹⁴C-iodoacetamide, increase about 2-fold during the sperm passage from the caput to caudal epididymides. Majority of the increased disulfides reside in the human protamine fractions.We thank Drs Jisnuson Svasti and Nongnuj Tanphaichitr for their valuable suggestions. This work was supported by the Faculty of Science, Mahidol University, and the Rockefeller Foundation.     

Stimulation of glycoprotein secretion in dispersed rat submandibular gland acini by cystic fibrosis serum

Summary Acini were enzymatically dissociated from rat submandibular gland and their mucous glycoproteins radiolabelled with¹⁴C-glucosamine. Sera from cystic fibrosis patients stimulated the release of labelled TCA/PTA — insoluble material from the cultured acinar cells to a significantly higher degree than did control sera.This work was supported by the Canadian Cystic Fibrosis Foundation and the Sellers Foundation.     

The role of sialic acid in 5-HT binding to synaptic membranes

Summary The high affinity binding of [¹⁴C]5-HT to nerve ending membranes isolated from rat brain is not affected by neuraminidase treatment. The specificity of ligand receptor interaction was demonstrated by displacement studies with tryptamine derivatives, noradrenaline, and acetylcholine.The expert technical assistance of Miss Christiane von Winterfeld is appreciated. This work was supported by a grant of the Deutsche Forschungsgemeinschaft.     

Dissociation of avidin-biotin complex in vivo

Zusammenfassung Es wurde mittels des mit¹⁴C markierten Biotins und mit¹³¹J markierten Avidins gezeigt, dass der Avidin-Biotin-Komplex, i.p. oder i.v. in Ratten injiziert, dissoziert war.

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This work was supported by a grant from the China Medical Board of New York, Inc. (Grant No. 70-127).     

Inhibition of platelet ADP and serotonin release by carbon monoxide and in cigarette smokers

Summary The release of¹⁴C-serotonin by ADP, epinephrine and arachidonic acid and the release of ADP by kaolin were measured in normal platelets in the presence and absence of carbon monoxide and in smokers' platelets. It is shown that carbon monoxide inhibits significantly the platelet release reaction. This function is also decreased in platelets obtained from heavy cigarette smokers.This work was supported by Veterans Administration Research Fund 8073-01.     

In vivo perfusion of the human ovary with 4-14C-dehydroepiandrosterone and 7α-3H-dehydroepiandrosterone35S-sulfate. Biosynthesis of steroid hormones in human gonads,V

Zusammenfassung Nach in-vivo-Perfusion eines menschlichen Ovars mit 4-¹⁴C-DHEA und 7-³H-DHEA-³⁵S-sulfat lagen rund 15% der freien C₁₉- und C₁₈-steroide im Ovarialvenenblut als³H- und 85% als¹⁴C-markierte Verbindungen vor. Die Fraktion der sulfokonjugierten Steroide, bestehend aus 60% Steroidsulfatiden und 40% Steroidsulfaten, enthielt etwa 69% doppeltmarkierte, 27%³H- und 4%¹⁴C-markierte Sulfokonjugate. Neben dem vorzugsweise direkten Metabolismus des sulfokonjugierten DHEA liess sich auch ein indirekter Stoffwechsel zu Androgenen und Östrogenen nachweisen.

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This investigation was supported by the Deutsche Forschungsgemeinschaft, 532 Bad Godesberg (Germany)     

In vivo oxidative coupling of anilines and phenolic anilines

Zusammenfassung Im Kern markierte¹⁴C-Anthranilsäure und Derivate wurden an Mikroorganismen, die Phenazin- und Phenoxazon-Farbstoffe produzieren, verfüttert. Der erfolgte Einbau beweist die oxydative Kupplung von Anilinen und phenolischen Anilinen in vivo.

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This work was supported by Grant GB-2290 of the National Science Foundation.     

The effect of hypoxia on hepatic cytochromes and heme turnover in rats in vivo

Summary We evaluated the effect of hypoxia (7% v/v) on hepatic heme turnover in vivo and microsomal heme protein content in male Sprague-Dawley rats. Hepatic heme protein turnover, measured as¹⁴CO-production during continuous infusion of 5-¹⁴C-aminolevulinic acid, a precursor of nonerythrogenic heme, was decreased 60% during hypoxia and returned to control levels promptly after reoxygenation. Hepatic cytochrome P-450 content was decreased in hypoxic and 24-h reoxygenated animals. We conclude that normobaric hypoxia decreases hepatic cytochrome P-450 which could contribute to decreased drug metabolism in hypoxia. This decrease is probably due to heme oxygenase-independent breakdown of hepatic heme.     

Effect ofd,l-glyceraldehyde on bacterial cells metabolism

Riassunto In aerobiosi lad-l-gliceraldeide a notevoli concentrazioni ha una lievissima azione inibente sulla ossidazione del glucosio e sulla incorporazione di leucina-C¹⁴. In condizioni di anaerobiosi invece lad-l-gliceraldeide in concentrazioni medie inibisce notevolmente sia la glicolisi che la incorporazione di leucina-C¹⁴.

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This work was carried out with the help of Consiglio Nazionale delle Ricerche (CNR).     

Thiamine transport by human intestine in vitro

Summary Surgical specimens of human gastrointestinal mucosa and muscle were incubated in vitro with thiaminethiazole-2-¹⁴C. Labelled thiamine uptake was uphill in mucosal tissues and downhill in muscle. Small intestinal mucosa accumulated labelled thiamine in a phosphorylated form, while gastric and colonic mucosa, as well as muscular layers of all gastrointestinal segments studied, did not.This work was supported in part by a grant from the Italian Research Council, Rome, Italy.     

Serum and liver radioactivity levels in mice after intraperitoneal and subcutaneous injection of [14C]orotic acid

Summary [¹⁴C]Orotic acid was rapidly distributed in blood after, both i.p. and s.c. injection but was not completely absorbed from the peritoneal cavity until 20 min after injection. S.c. injection should be an acceptable alternative to i.p. injection although the incorporation into the liver acid soluble- and RNA-fractions was somewhat delayed after the s.c. injection.This work was supported by grants from the Carl Trygger Foundation and the Foundation of Director Albert Påhlsson.     

Diabetes alters drug metabolism-in vivo studies in a streptozotozin-diabetic rat model

Summary The influence of experimental streptozotozin-induced diabetes on hepatic drug metabolism in vivo has been studied in rats, using¹⁴CO₂-exhalation after¹⁴C-aminopyrine injection. Male diabetic rats showed a decreased (–18%), females an increased (+19%)¹⁴CO₂-exhalation compared to controls, indicating altered hepatic drug metabolism due to diabetes.     

A new peripheral monoamine oxidase inhibitor: 2,9-dimethyl-β-carbolinium iodide

Resumen Yoduro de 2, 9-dimetilo-carbolinio (DMCI) y no sus metabolitos inhibió la enzyma monoamino oxidasa y elevó¹⁴C-serotonia en el corazón e higado, pero no en el cerebro de ratas.

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This work is taken in part from the M. S. thesis presented byP. M. Gardner to the University of Texas Graduate School of Biomedical Sciences at Houston, 1971.