The presence of 2,3-butanediol in the blood of chronic alcoholics admitted to an alcohol treatment center.

Fifty-one of sixty-three unselected alcoholic subjects had 2,3-butanediol in their blood in concentrations ranging from 0.011 to 0.775 mM upon admission to an alcohol detoxification center. The concentration of 2,3-butanediol was below the detection limit of 0.01 mM in twelve non-alcoholic controls. Eighteen hours after admission, second blood samples showed no ethanol in all eleven subjects tested. 2,3-Butanediol levels declined in all of the patients and became undetectable in eight.

Short- and long-term effects of ethanol administration in vivo on rat liver HMG-CoA reductase and cholesterol 7alpha-hydroxylase activities.

Short- and long-term effects of ethanol on HMG-CoA reductase (EC 1.1.1.34) and cholesterol 7alpha-hydroxylase activities in rat liver have been investigated. Neither the reductase nor the hydroxylase activity as measured in vitro was significantly affected within 2 hr after a single intraperitoneal injection of ethanol (7 mmol per 100g body weight), whether tested at the diurnal low or the diurnal high point of activity. Although chronic ethanol feeding for 21 days did not affect the diurnal rhythm of either of these enzyme activities, it caused a 29% decrease in HMG-CoA reductase activity and a 56% decrease in cholesterol 7alpha-hydroxylase activity at the diurnal high point. The same chronic ethanol feeding caused a moderate increase in serum cholesterol and a significant increase in hepatic cholesterol concentration. On the basis of these findings, it is suggested that the decreased rate of cholesterol degradation to bile acids may play a significant role in the accumulation of cholesterol in the liver after chronic ethanol feeding.

Effect of chronic ethanol feeding upon the catabolism of protein and lipid moieties of chylomicrons and very low density lipoproteins in vivo and in the perfused heart system.

Effect of chronic ethanol feeding for 6 weeks to male Wistar rats upon the catabolism of rat chylomicrons and very low density lipoproteins was investigated both in vivo and in the perfused heart system. The exponential decay curves in the plasma compartment or in the perfused heart system of these lipoproteins labeled in the protein or triacylglycerol or cholesterol moieties were determined. It was found that chronic ethanol feeding inhibited the catabolism of both protein and triacylglycerol moieties by 26-35%, whereas that of the cholesterol moiety was inhibited by 67-71%. Since the catabolism of the triacylglycerol moiety takes place essentially in the extrahepatic tissues while that of the cholesterol moiety occurs in the liver, it is concluded that ethanol affects the catabolism of triacylglycerol-rich lipoproteins in the liver more than in the extrahepatic tissues.

Relationship of alcoholic hyperlipidemia to the feed-back regulation of hepatic cholesterol synthesis by chylomicron remnants.

Pairfeeding of ethanol liquid diet for 6 weeks to male Wistar rats resulted in defective extrahepatic as well as hepatic catabolism of rat lymph chylomicrons. Based upon the exponential decay curves of the chylomicrons in the blood compartment it was concluded that chronic ethanol feeding caused 30 and 67% decreases in the rate of degradation of the triacylglycerol and cholesterol moieties, respectively. As a consequence, abnormal chylomicron remnants accumulated in chronic ethanol-fed but not in control animals. These abnormal remnants were not as efficient as the normal remnants in causing the feedback inhibition of cholesterol synthesis in hepatocytes from normal meal-fed rats. Furthermore, the hepatocytes from chronic ethanol-fed animals exhibited defective feedback regulation of cholesterol synthesis by normal chylomicron remnants. The net result of all these abnormalities caused by chronic ethanol feeding would be the delayed clearance of triacylglycerol-rich lipoproteins from the blood compartment and enhanced synthesis and secretion of the triacylglycerol-rich lipoproteins by the liver.

Studies on the visual pigment and the indicator yellow analogues formed from 5,6-monoepoxyretinal.

1. A new visual pigment has been isolated from retinae of rats maintained on 5,6-monoepoxyretinal for a period of 6 months. 2. Indicator yellow analogues from 5,6-monoepoxyretinal, namely 5,6-monoepoxyretinylidenemethylamine and 5,6-monoepoxyretinal oxime, have been prepared in a homogeneous state, the latter being obtained crystalline. 5,6-Monoepoxyretinylidenedimethylammonium iodide has also been prepared. 3. The spectroscopic properties, analytical data and antimony trichloride colour reactions of these indicator yellow analogues confirm their Schiff base structure. 4. The nature of chromogens formed from 5,6-monoepoxyretinylideneamino compounds with antimony trichloride and concentrated sulphuric acid is obscure although the chromogens resemble one another very closely. 5. 5,6-Monoepoxyretinylidenemethylamine and 5,6-monoepoxyretinylidenedimethylammonium iodide are very labile, whereas 5,6-monoepoxyretinal oxime is quite stable. 6. Hydrolysis of 5,6-monoepoxyretinylidenemethylamine as a function of pH reveals that, though 5,6-monoepoxyretinylidenemethylammonium ions are stable, the un-ionized compound readily hydrolyses to 5,6-monoepoxyretinal. This hydrolysis can be prevented by excess of un-ionized methylamine and hastened by formaldehyde. 7. The bathochromic shift in the lambda(max.) of the ;acid form' of 5,6-monoepoxyretinylidenemethylamine is due to the formation of its ammonium salt. The spectrum of the ;acid form' is identical with that of 5,6-monoepoxyretinylidenedimethylammonium iodide in ethanol. This is also evidence for the quaternary state of the nitrogen atom during the ;acid shift' of 5,6-monoepoxyretinylidenemethylamine. 8. The significance of 5,6-monoepoxyretinal and the corresponding indicator yellow analogues in the formation and properties of a new visual pigment is discussed.

Preparation, properties and metabolism of 5,6-monoepoxyretinoic acid.

1. Methyl retinoate has been converted into methyl 5,6-monoepoxyretinoate by reaction with monoperphthalic acid. The epoxy acid ester on alkaline hydrolysis gave 5,6-monoepoxyretinoic acid. 2. Treatment of the 5,6-monoepoxy compounds with ethanolic hydrochloric acid gave the corresponding 5,8-epoxy (furanoid) compounds. 3. With lithium aluminium hydride, the acid and the ester groups were selectively reduced to primary alcohols. 4. Administration of methyl 5,6-monoepoxyretinoate intraperitoneally and subcutaneously had good growth response in vitamin A-deficient rats. 5. 5,6-Monoepoxyretinoic acid, when given intraperitoneally as the sodium salt, was 157% as active as all-trans-retinyl acetate. 6. Methyl 5,6-monoepoxyretinoate was hydrolysed to the epoxy acid by rat-liver homogenate. It had 35% of the biological activity of all-trans-retinyl acetate in the rat when given orally.

Metabolism and biological potency of retro-retinyl acetate in the rat.

1. retro-Retinyl acetate was shown to exert its biological activity by conversion into vitamin A. 2. When administered orally, retro-retinyl acetate was hydrolysed to retro-retinol in the intestine, isomerized to retinol and esterified before being transported to the liver for storage. 3. Administration of the compound at as high a dose as 4.0mg./day for 4 days led to the accumulation of both vitamin A and retro-vitamin A in the liver. The amount of retro-vitamin A in liver gradually decreased until it was almost completely converted into vitamin A in 18 days. 4. Intraperitoneal administration of the compound led to the accumulation of both vitamin A and retro-vitamin A in liver and other tissues. No vitamin A was detected in any tissue of rats receiving retro-retinyl acetate intraperitoneally after enterectomy. 5. The small intestine is the major site of conversion of retro-vitamin A into vitamin A. The conversion could also be demonstrated by everted intestinal sacs. 6. The biological potency of retro-retinyl acetate determined by the rat-growth assay was 20.5% that of all-trans-retinyl acetate, when given orally.

Effect of p-chlorophenoxyisobutyrate (CPIB) fed to rats on hepatic biosynthesis and catabolism of ubiquinone.

The effect of p-chlorophenoxyisobutyrate (CPIB) feeding on cholesterol and ubiquinone metabolism in rats was investigated. The results obtained from acetate-1-(14)C and mevalonate-2-(14)C incorporation studies both in vivo and in vitro confirm the results of other workers that CPIB feeding caused a metabolic block in the conversion of acetate to mevalonate, thereby inhibiting over-all steroidogenesis. Liver ubiquinone synthesis was inhibited in CPIB-fed rats, but a block in the catabolism of the ubiquinone resulted in accumulation of ubiquinone in CPIB-fed animals.

Relationship of endocrine status on the stimulatory effect of ethanol on hepatic very low density lipoprotein synthesis.

The normal stimulatory effect of an acute oral dose of ethanol on hepatic very low density lipoprotein synthetic rate is abolished in thyroidectomized rats but not in adrenalectomized rats. This lack of stimulation by ethanol can be explained in part by the decreased rate of hepatic fatty acid esterification to neutral lipids in thyroidectomized animals.

Alcohol and very low density lipoprotein synthesis and secretion by isolated hepatocytes.

Labeled leucine can be used to measure accurately the rate of both total and secretory protein synthesis by isolated hepatocytes if at least 1 mM leucine is added to the incubation medium, even in the presence of 50 mM ethanol. Using this technique it was found that ethanol caused a significant inhibition of very low density lipoprotein (VLDL) as well as total protein synthetic rates in hepatocytes from both fed and fasted rats. In contrast, a single acute oral dose of ethanol to fasted rats caused within 4 hr a threefold stimulation in the rate of VLDL synthesis without affecting the total protein synthetic rate in the hepatocyte system.

The metabolism of retinyl methyl ether in the rat in vivo.

1. Retinyl methyl ether was converted into vitamin A in vitamin A-deficient rats regardless of whether administered by oral, intraperitoneal, intramuscular or subcutaneous route; intramuscular administration seemed to be the best for conversion as well as storage. 2. Significantly, unchanged retinyl methyl ether was also found in the liver after oral administration but not after administration by other routes. 3. Oral administration of 1mg of retinyl methyl ether led to a progressive increase in liver vitamin A with time reaching a value of 16% of administered dose after 24h. No retinyl methyl ether was detectable in liver at any time-interval in this experiment. 4. Conversely, oral administration of 4mg of retinyl methyl ether/day for 4 days led to the accumulation of 25% of the dose as unchanged retinyl methyl ether in the liver 1 day after the last dose; however, it was gradually but completely converted into vitamin A over a period of 18 days. 5. The significance of these findings with special reference to the fundamental metabolism of vitamin A, the site of conversion of retinyl methyl ether into vitamin A, the relative efficiency of various routes of administration and its biological activity are discussed.

Control of the synthesis of fatty-acid synthetase in rat liver by insulin, glucagon, and adenosine 3':5' cyclic monophosphate.

The usual increase in the activity of liver fatty-acid synthetase that occurs on refeeding of a fat-free diet to previously fasted rats is abolished in diabetic animals. Insulin specifically restores this increase by enhancement of the rate of synthesis of fatty-acid synthetase. However, glucagon and cyclic AMP inhibit the increase in the activity of fatty-acid synthetase. Therefore, the concentration of fatty-acid synthetase in rat liver is under the control of the relative concentrations of insulin and glucagon.

Purification and properties of carotene 15,15'-dioxygenase of rabbit intestine.

Carotene 15,15'-dioxygenase, which oxidizes carotenoids to retinal, has been purified up to 200-fold from rabbit intestine by ammonium sulfate fractionation, heat treatment, and acetone precipitation. With beta-apo-10'-carotenol as the substrate, the purified enzyme has a pH optimum of 7.8, a K(m) of 6.7 x 10(-5) m, and a V(max) at 37 degrees C of 9 nmoles of retinal/mg protein/hr. The purified enzyme is inhibited by ferrous ion-chelating agents such as alpha,alpha'-dipyridyl and o-phenanthroline, and by sulfhydryl-binding agents such as iodoacetamide, N-ethylmaleimide, and p-chloromercuribenzoate. The latter inhibitory effects are reversed by reduced glutathione. The cleavage of beta-apo-10'-carotenol is competitively inhibited by its acetylenic analog, 15,15'-dehydro-beta-apo-10'-carotenol. The enzyme is present in the intestinal mucosa of several mammals, the chicken, the tortoise, and a freshwater fish, but it is absent from cat intestinal tissue.