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PubMed1962

Metabolic function of branched-chain volatile fatty acids, growth factors for ruminococci. II. Biosynthesis of higher branched-chain fatty acids and aldehydes.

Allison, M. J. (Dairy Cattle Research Branch, USDA, Beltsville, Md.), M. P. Bryant, I. Katz, and M. Keeney. Metabolic function of branched-chain volatile fatty acids, growth factors for ruminococci. II. Biosynthesis of higher branched-chain fatty acids and aldehydes. J. Bacteriol. 83:1084-1093. 1962.-A number of strains of rumen bacteria require branched-chain volatile fatty acids for growth. A strain of Ruminococcus flavefaciens that requires either isovalerate or isobutyrate incorporates radioactive carbon from isovalerate-1-C(14) and isovalerate-3-C(14) into leucine and into the lipid fraction of the cells. Evidence obtained by both paper and gas chromatography indicated that most of the label in the lipid of cells grown in isovalerate-1-C(14) was in a branched-chain 15-carbon fatty acid, with some in a 17-carbon acid; about 7.5% of the C(14) was recovered in a branched-chain 15-carbon aldehyde. The aldehydes were in the phospholipid fraction and were presumably present as plasmalogen.A strain of R. albus was shown to require isobutyrate, 2-methyl-n-butyrate, or 2-ketoisovalerate for growth. This strain did not incorporate appreciable C(14) from isovalerate-1-C(14) or isovalerate-3-C(14). When grown in a medium containing isobutyrate-1-C(14), most of the cellular C(14) was found in the lipid fraction. Analysis of the lipid demonstrated that the label was present mainly as branched-chain 14-carbon and 16-carbon fatty acids, with 11% of the C(14) present in 14- and 16-carbon carbonyl compounds, presumably branched-chain aldehydes.Branched-chain 14-, 15-, and 16-carbon fatty acids are major components of the lipids of these rumen bacteria. The possibility that these acids and aldehydes, which are found in ruminant body and milk lipids, may be of microbial origin is discussed.

Aldehydes↗

PubMed1964

METABOLISM OF MEVALONIC ACID BY LACTOBACILLUS PLANTARUM.

Durr, I. F. (American University of Beirut, Beirut, Lebanon), and A. N. Shwayri. Metabolism of mevalonic acid by Lactobacillus plantarum. J. Bacteriol. 88:361-366. 1964.-Lactobacillus plantarum strain 8014-H(2), unlike other lactobacilli studied, does not require mevalonic acid for growth, but growing and resting cells utilize it only for the synthesis of nonsaponifiable lipids. Upon the incubation of washed cells with mevalolactone-2-C(14), the label appeared in the lipids but not in CO(2). On the other hand, when mevalolactone-1-C(14) was used, the label appeared in CO(2) but not in lipids. For every mole of CO(2) liberated, 1 mole of radioactive carbon was introduced in the lipids, suggesting that terpenic polymers were synthesized. Amino acids did not stimulate the utilization of mevalonic acid. Starved cells could not synthesize nonsaponifiable lipids from mevalonic acid unless glucose was supplied. Sodium fluoride (0.14 m), 2,4-dinitrophenol (0.003 m), p-hydroxymercuribenzoate (0.0013 m), potassium phosphate (0.1 m), and ammonium formate (0.04 m) were potent inhibitors. Cells metabolized only one isomer of dl-mevalonic, and utilized the salt form at least twice as efficiently as the lactone. Optimal synthesis of lipids from mevalonic acid occurred aerobically, at pH 5 and 30 C.

2,4-Dinitrophenol↗

PubMed1969

Uptake of glucose-l-14C by Pullularia pullulans.

Pullularia pullulans cells were grown in a medium containing yeast extract, malt extract, glucose, and nutrient salts, in addition to glucose-1-(14)C. The lipids extracted from the cells were fractionated by use of a single column packed with silicic acid. Of the total radioactive carbon added to the culture medium, the neutral lipid fractions contained 24.8%, whereas the phospholipid portions contained only 2.1%. The largest amount (16.5%) of (14)C among the neutral lipids was found in the fraction containing the free sterols. Among the phospholipids, the largest amount (1.1%) was found in phosphatidylserine and phosphatidylethanolamine. The second largest amount (9.6%) of the total (14)C used was found in trehalose, followed by carbon dioxide (7.3%).

Carbon Isotopes↗

PubMed1991

Acetate uptake by intestinal brush border membrane vesicles.

The mechanism of acetate absorption in the small intestine is not yet established. One possible mechanism is by carrier mediated Na(+)-acetate cotransport since acetate, like glucose, stimulates intestinal Na+ and water absorption in vivo. Uptake of radioactive carbon acetate by small intestinal brush border membrane vesicles was not saturable or Na+ dependent and did not respond to osmotic shrinkage of the vesicles. This suggests that acetate binds to the membranes but is not transported into the intravesicular space and argues against carrier mediated Na+ acetate cotransport. These results are consistent with acetate absorption by a non-mediated diffusion and suggest that the stimulation of water and Na+ absorption by acetate in vivo is largely due to osmotic forces and solvent drag.

Acetates↗

PubMed1976

Pyrimidine reducing enzymes of rat liver.

Dihydrouracil dehydrogenase (NADP+) (EC 1.3.1.2) was partially purified from the cytosol fraction of rat liver and fractionated by disc gel electrophoresis. A major and minor band were visualized by staining for enzyme activity. The substrate specificity of these bands was investigated. It was found that both bands were two to three times more active with dihydrothymine as substrate than with dihydrouracil in the presence of NADP+ and the optimum pH of 7.4. Mitochondrial fractions containing most of the NADH-dependent uracil reductase of rat liver cells were fractionated by centrifugation in sucrose density gradients. Two procedures involving linear or discontinuous gradients were used. By both, good separation of NADH- and NADPH- dependent reductases was achieved. Marker enzyme studies supported the view that the NADH-dependent enzyme is located principally in mitochondria whereas the NADPH-dependent enzyme is mainly in plasma and endoplasmic reticulum membranes. For the NADH-dependent reductase the apparent Km for thymine at pH 7.4 was 1.39 times that found for uracil whereas for the NADPH-dependent enzyme the apparent Km values were similar for the two substrates at this pH. Dihydrouracil was the principal product isolated by paper chromatography from the reaction mixture containing a partially purified fraction of mitochondria, uracil and NADH at pH 7.4. This fraction also catalyzed the formation of radioactive carbon dioxide from [2-14C]uracil. The proportion of CO2 formed by the mitochondria was about 10% of that formed by the original homogenate.

Aldehyde Oxidoreductases↗

PubMed1976

Mammalian fatty acid synthetase. III. Characterization of human liver synthetase products and kinetics of methylmalonyl-CoA inhibition.

When propionyl-CoA was substituted for either acetyl-CoA or butyryl-CoA in the presence of [14C]malonyl-CoA and NADPH, the pure human liver fatty acids synthetase complex synthesized only straight-chain, saturated, 15- and 17-carbon radioactive fatty acids. At optimal concentrations, propionyl-CoA was a better primer of fatty acid synthesis than acetyl-CoA. Methylmalonyl-CoA inhibited the synthetase competitively with respect to malonyl-CoA. The Ki was calculated to be 8.4 muM. These findings provide an in vitro model and offer a direct explanation at the molecular level for some of the abnormal manifestations observed in diseases characterized by increased cellular concentrations of propionyl-CoA and methylmalonyl-CoA.

Chromatography, Gas↗

PubMed1977

Action of inhibitors on monoamine and diamine metabolism in the rat.

The effects of a series of inhibitors of monoamine oxidase (EC 1.4.3.4) and diamine oxidase (EC 1.4.3.6) and of two chelating agents were studied in rats, with respect to the catabolism of labeled pentylamine and putrescine to radioactive carbon dioxide. D-Tranylcypromine, clorgyline, and deprenyl inhibited oxidation of the monoamine, with essentially no effect on putrescine, under our test conditions. Aminoguanidine inhibited putrescine but not pentylamine oxidation. Iproniazid, isoniazid, and Lilly 51641 affected the catabolism of both amines. Pargyline inhibited putrescine oxidation, apparently in a reversible manner.

Amine Oxidase (Copper-Containing)↗

PubMed2002

Paving the path.

Fortuitous preparation and experiences led to the opportunity to use radioactive carbon dioxides to discern the path of carbon in photosynthesis. The search for the CO2 acceptor led to recognition of the growth stimulatory effect of methanol and its derivatives. With the techniques developed, radiochromatographic exploration led to discovery of major membrane lipids containing phosphorus, sulfur, and arsenic.

Botany↗

PubMed1978

Systemic and regional flow distribution in normotensive and spontaneously hypertensive young rats subjected to lifetime beta-adrenergic receptor blockade.

To determine quantitatively organ blood flow distribution as the result of lifelong beta-adrenergic receptor blockade, 23 and 24 normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats, respectively, were treated from conception with tap water (control; 10 WKY and 8 SHR), propranolol (0.5 mg/ml drinking water; 6 WKY and 8 SHR), or timolol (0.5 mg/ml drinking water; 7 WKY and 8 SHR) via placental circulation, mothers' milk, and drinking water. At 12 weeks of age all six groups were studied hemodynamically under ether anesthesia using an electromagnetic flowmeter and radioactive carbonized (15 micrometer) microspheres. Untreated SHR demonstrated normal cardiac output (CO) and CO distribution to all organs except for myocardium and testes, thereby confirming our previous work. With either propranolol or timolol treatment the course of development and maintenance of arterial pressure was no different than the pure-tap-water-fed WKY and SHR despite an approximate 30% reduction in CO. Further, with both beta-receptor antagonists CO distribution was significantly reduced to skeletal muscle (p less than 0.001), unchanged to the heart, and increased (p less than 0.05) to the remaining organs (including kidneys and brain) in both groups. Thus, as a result of lifelong beta-adrenergic receptor blockade, CO was reduced; and this was associated with a redistribution of blood flow so that flow to the kidney, brain, and splanchnic organs could be maintained at the expense of skeletal muslce perfusion.

Animals↗

PubMed1975

Adipose tissue metabolism in essential fatty acid deficienty. Effects of prostaglandin e1, epinephrine, and ACTH.

In an effort to better define some of the metabolic changes that accompany essential fatty acid deficiency (EFAD), we studied glucose metabolism in adipose tissue of EFAD and normal mice under basal conditions and in the presence of prostaglandin E1 (PGE1), epinephrine, and ACTH1-18. Isolated fat cells were incubated in Krebs-Ringer bicarbonate medium containing glucose 1(-14C) or 6(-14C), and the incorporation of radioactive carbon into CO2, total fat, fatty acids, and glyceride-glycerol was determined. It was found that EFAD increased glucose uptake over controls which could be attributed to increased oxidation to CO2 and fatty acid synthesis. The contribution of the pentose cycle to glucose oxidation was 50-80% higher in EFAD adipocytes as compared to controls. ACTH1-18 (0.1 mug/ml) suppressed this by 18 and 30% in the control and EFAD groups, respectively, while epinephrine decreased pentose cycle activity by 83 and 55% in the two groups, respectively. PGE1 alone had no significant effect, but in combination with epinephrine it abolished the inhibitory action of the catecholamine in both groups. It is suggested that, although EFA serve as prostaglandin precursors, the effects of EFAD on the metabolism of fat cells cannot be reversed by PGE1, in vitro. However, these fat cells retain their responsiveness to the action of both lipolytic (ACTH and epinephrine) and antilipolytic (PGE1) agents.

Adipose Tissue↗

PubMed1976

The distribution of 14c from [U-14c]glucose in mice using whole-body autoradiography.

Tissue distribution of radioactive carbon from [U-14C]glucose in the mouse in vivo was studied by whole-body autoradiography. The mice were frozen with Dry-Ice-acetone at 0.5, 1, 5 and 30 min, 1 and 24 hr and 1 and 3 weeks after intraperitoneal injection of [U-14C]glucose. Whole-sagittal sections of the frozen mouse, obtained by using a microtome in a cryostat, were dried in a cryostat and autoradiographed. The resulting dry autoradiographs are called untreated autoradiographs in the present work. The sections were then fixed in cold 6% (w/v) HClO4, dried at room temperature and again autoradiographed. Autoradiographs that have undergone this process are referred to as treated autoradiographs. In both untreated and treated autoradiographs, within 1 min following injection of the labeled glucose, the abdominal cavity had the highest autoradiographic density. At 1 hr, density became highest in Harder's, sublingual and duodenal glands, large intestinal mucosa and tongue, and after 3 weeks, no autoradiographic denisty was present.

Adipose Tissue, Brown↗

PubMed2006

Effect of intratesticular injection of lidocaine on cardiovascular responses to castration in isoflurane-anesthetized stallions.

OBJECTIVE: To evaluate the effect of intratesticular administration of lidocaine on cardiovascular responses and cremaster muscle tension during castration of isoflurane-anesthetized stallions. ANIMALS: 28 healthy stallions (mean +/- SD age, 4.2 +/- 2.8 years) with no testicular abnormalities that were scheduled for castration. PROCEDURE: Each horse was given acepromazine (20 microg/kg, IM), romifidine (50 microg/kg, IV), and butorphanol (20 microg/kg, IV). Anesthesia was induced with ketamine (2.5 mg/kg, IV) and midazolam (50 microg/kg, IV) and maintained with isoflurane (1.7% end-tidal concentration). After 10 minutes at a stable anesthetic plane, a needle was placed in each testicle and either no fluid or 15 mL of 2% lidocaine was injected; 10 minutes after needle placement, surgery was commenced. Pulse rate and arterial blood pressures were measured invasively at intervals from 5 minutes prior to castration (baseline) until 5 minutes after the left spermatic cord was clamped. The surgeon subjectively scored the degree of cremaster muscle tension. In 2 horses, lidocaine labeled with radioactive carbon (C(14)) was used and testicular autoradiograms were obtained. RESULTS: Compared with baseline values, castration significantly increased blood pressure measurements; intratesticular injection of lidocaine decreased this blood pressure response and cremaster muscle tension. In 2 horses, autoradiography revealed diffuse distribution of lidocaine into the spermatic cord but poor distribution into the cremaster muscle. CONCLUSIONS AND CLINICAL RELEVANCE: In isoflurane-anesthetized stallions, intratesticular injection of lidocaine prior to castration appeared to decrease intraoperative blood pressure responses and cremaster muscle tension and may be a beneficial supplement to isoflurane anesthesia.

Anesthetics, Local↗

PubMed1993

The fate of ingested 14C-urea in the urea breath test for Helicobacter pylori infection.

The metabolic fate of the radioactive carbon in the 14C-urea breath test for Helicobacter pylori was investigated in 18 subjects. After ingestion of labelled urea, breath was sampled for 24 h, and urine was collected for 3 days. Subjects were designated high or low expirers on the basis of their breath counts, and this agreed well with H. pylori serologic analyses. When given 185 or 37 kBq of 14C-urea, 51% (SD = 16%, n = 11) of the label was recovered from the breath of high expirers, and 7% (SD = 3%, n = 7) from the breath of low expirers. The mean combined urinary and breath recovery for high expirers was 86% (SD = 7%), and for low expirers it was 97% (SD = 3%). It is concluded that the long-term retention of 14C from ingested 14C-urea is low. The results enable a more accurate estimation to be made of radiation exposure resulting from the 14C-urea breath test.

Breath Tests↗

PubMed1975

Exposure to methylene chloride. III. Metabolism of 14C-labelled methylene chloride in rat.

The accumulation of methylene chloride and its metabolites in different organs and tissues was studied in an experimental series comprising 10 rats. Each rat was exposed for 1 h to radioactive methylene chloride (14C) in a concentration amounting to 1,935 mg/m3 in inspiratory air. Radioactive carbon atoms were found in the isolated carbon monoxide after exposure. There was also a close correlation between the activity of carbon monoxide extracted from the blood sample and the amount of carboxyhemoglobin (COHb) in the specimen. The largest concentration of methylene chloride and its metabolites per gram of tissue was found in white adipose tissue. This concentration had declined by more than 90% 2 h after exposure, whereas the concentration in the liver declined by about 25% during the same period. The amount accumulated in the brain displayed a decline of about 75% 2 h after exposure. Thus the examination showed that the increased concentration of COHb in the blood during exposure to methylene chloride is due to the metabolism of methylene chloride into carbon monoxide.

Adipose Tissue↗

PubMed1976

[Biosynthesis of 14C- and 35S-lincomycin using different sources for the label].

The sources of radioactive labels were chosen for biosynthesis of labeled lincomycin. The levels of the label incorporation into lincomycin were high with all the sources used when the lincomycin-producing organism was cultivated on the synthetic medium as compared to the complex medium. Incorporation of the label into lincomycin was most effective when I14C- or 214C-thyrosine was used as the precursors. These precursors were effective in both the complex and the synthetic media. In production of significant amounts of the labeled lincomycin I14C- or 214C-sodium propionate, I14C- or 142C-sodium acetate and 14C-protein hydrolysate may be used as the sources of the radioactive carbon. In production of 35S-lincomycin K235SO4 may be used as the source of the label. The optimal conditions for biosynthesis of 14C- and 35S-lincomycin were developed (concentration of some components of the medium, time of the label addition and others).

Acetates↗

PubMed1975

[Effect of trypsin-like enzyme inhibitor on certain metabolic processes in the acute period of experimental myocardial ischemia].

The effect of trasylol upon the activeness of proteolysis in the cytoplasm and mitochondrial-lysosomal fractions of the heart muscle was studied in the acute experimental period of myocardial ischaemia (5 days) along with a determination of the spectrum of the iso-enzymes of the lactate- and malate- dehydrogenases. For the evaluation of oxidation processes in vitro the iections. Trasylol was found to limit the proteolysis in the cytostructures of the myocardium cell, to increase the activity of the transaminases, as well as to help the normalization of thespectrum of the NAD-dependent iso-enzymes. At the same time, under the effect of the employed drug, the myocardial consumption of the radioactive carbon from the acetate Na-2C-14 increases.

Animals↗

PubMed2002

The use of the radioisotope method in studies of pesticide penetration into the eyeball.

The studies concerning the effects of pesticides on the human body focused mainly on their local action or chronic poisoning of the organism. In this study we examine the pesticide penetration into the eyeball resulting from direct contact with the eye. We used an isotope-labelled carbamate pesticide -- carbaryl. The determinations of the amount and concentration of this substance in the cornea, aqueous humour, vitreous humour and retina were performed using the method measuring beta radiation emitted by radioactive carbon. The results revealed measurable concentrations of labelled carbamate in the cornea and aqueous humour 10 and 30 min after application. The levels of this pesticide in the vitreous humour and retina were very low and difficult to analyse statistically. The described method appears to be useful in determining the range and rate of eye penetration by environmental toxins having direct contact with the eyeball.

Animals↗

PubMed1992

Exogenous origin of n-alkanes in pathologic scale.

BACKGROUND: Although n-alkanes accumulate in some disorders of cornification, recent studies using radioactive carbon 14 content by accelerator mass spectrometry point to an exogenous origin for alkanes in normal stratum corneum, and their derivation in congenital ichthyosiform erythroderma remains controversial. DESIGN AND RESULTS: Using 14C content to measure sample age, the n-alkane fractions from two patients with congenital ichthyosiform erythroderma contained no detectable contemporary materials. By electron microscopy, alkane-enriched emollients (petrolatum [Vaseline]) permeated to all levels of stratum corneum of hairless mice, expanding the intercellular domains and distorting membrane bilayers. Similar ultrastructural changes were also observed in the stratum corneum of patients with congenital ichthyosiform erythroderma. When alkanes were excluded, no differences in lipid content were evident between two forms of autosomal recessive ichthyosis. CONCLUSIONS: These data demonstrate that scale n-alkanes in disorders of cornification derive from environmental sources and indicate the pervasiveness of petroleum-based emollients in skin. Therefore, epidermal lipid analyses must be interpreted with caution. However, these studies do not rule out an important therapeutic and/or pathogenic role for exogenous n-alkanes in skin.

Adult↗