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Biomedical subjects

E C Larkin

Publications and source records attributed to E C Larkin.

At least 55 records · Page 3Linked to original sources
PubMed1984

Fatty liver caused by chronic alcohol ingestion is prevented by dietary supplementation with pyruvate or glycerol.

Earlier studies showed that the fatty liver, caused by feeding rats the Lieber-DeCarli alcohol diet for four weeks, was prevented if the diet was supplemented with dihydroxyacetone (22 g/l), pyruvate (22 g/l) and riboflavin (2.2 g/l). In the present study, we observed that fatty liver was prevented if the alcohol diet was supplemented with glycerol and lactate (22 g/l each) and riboflavin (2.2 g/l). Hence, the prevention of alcoholic fatty liver by the dietary supplementation with dihydroxyacetone and pyruvate may not be related to their capacity to serve as hydrogen acceptors and to oxidize NADH produced during ethanol metabolism. When rats were fed the alcohol diet supplemented with either glycerol or pyruvate, the hepatic triglyceride (TG) levels were similar to those in rats pair-fed a Lieber-DeCarli control diet in which alcohol was replaced with an isocaloric amount of dextrins. Therefore, the prevention of fatty liver does not require the simultaneous presence of several supplements. Dietary dihydroxyacetone or riboflavin did not reduce alcoholic fatty liver. Supplementation of the ethanol diet with isocaloric amounts of lactate or glucose, instead of pyruvate, did not abolish the development of fatty liver but caused a marked reduction in the hepatic TG levels. Animals fed the alcohol diet consumed only small amounts of carbohydrate for long periods of time. Since the inclusion of glucose or its metabolites in the alcohol diet fed to rats caused a marked decrease in the liver TG content, it is likely that the production or prevention of fatty liver is related to carbohydrate metabolism.

Animals↗
PubMed1984

Hepatic origin of triglycerides in fatty livers produced by the continuous intragastric infusion of an ethanol diet.

Male Wistar rats were maintained for 30 days on an independent and continuous intragastric infusion of ethanol and nutritionally defined liquid diet containing only a small amount of corn oil (CO-4.9% calories). Ethanol intake was progressively increased from 32% to 40.4% of the total calories to maintain a high degree of intoxication during this period. Rats in the control group were infused with an isocaloric diet in which alcohol was replaced by dextrose. The liver triglyceride (TG) content of rats given alcohol (61.5 +/- 16.4 mg/g) was ca. 10-fold greater than that of controls (5.9 +/- 2.1 mg/g) and similar to that observed previously in rats fed an ethanol diet containing high levels of fat (35% and 43% calories). In TG of fatty liver, the level of 18:2 was small (3%), even though CO in the diet contained a high level of this acid. Furthermore, 16:1 and 16:0 contents were markedly elevated (16% and 40%, respectively) despite the fact that CO did not contain 16:1 and had only a small amount of 16:0. Liver TG having a fatty acid (FA) composition markedly different from that of CO and the presence of high levels of 16:1 and 16:0 indicate that the TG accumulated in the fatty liver originated from hepatic lipogenesis rather than from dietary fat.

Animals↗
PubMed1984

Alcohol and the blood.

Pathologic effects of ethanol on hematopoietic tissue can result directly from alcohol ingestion or from secondary nutritional deficiencies or hepatic disease. The clinician will often confront an array of overlapping syndromes in the alcoholic patient which involve abnormalities of erythrocytes, leukocytes, and platelets.

Alcoholic Intoxication↗
PubMed1983

Reduced plasma lecithin cholesterol acyl transferase activity in rats fed iron-deficient diets.

An iron-deficient diet containing no fat (FF-Fe) or containing either 14% hydrogenated coconut oil (HCNO-Fe) or 14% corn oil (CO-Fe) was fed to separate groups of rats for 10 weeks. In the control group, the corresponding iron-supplemented diets were fed FF+Fe, HCNO+Fe, CO+Fe. When rats were fed iron-deficient diets, their plasma lecithin cholesterol acyl transferase (LCAT) activity was significantly reduced as compared to controls. Their plasma also contained releatively more cholesteryl esters (CE) than free cholesterol (CH). In rats fed FF+Fe and CO+Fe diets, plasma contained similar levels of CE and CH. In those fed HCNO+Fe diet, plasma had 40% less Ce than CH. Red cell CH content was significantly greater in the CO-Fe group. Iron deficiency, as indicated by low blood hemoglobin (Hb) and hematocrit (Hct) values, was also observed only in this group. The triglyceride and phospholipid contents of plasma in rats fed iron-deficient diets were significantly lower than of those in the control groups. Thus, changes in LCAT activity and CE/CH ratio in plasma showed the effect of iron-deficient diet consumption even before the blood Hb and Hct levels were reduced.

Animals↗
PubMed1983

Complexities in lipid quantitation using thin layer chromatography for separation and flame ionization for detection.

The use of thin layer chromatography (TLC) for separation (using silica gel coated quartz rods) and subsequent flame ionization for detection (FID) was examined to determine whether this method could be used for the quantitation of lipids. However, response factors (RF) for various lipids were different and depended upon several variables including the amount of material analyzed. For example, RF were 3-fold greater when 10 micrograms of tripalmitin was analyzed as compared to 1 microgram of the same material. The amount of lipid detected by FID was also dependent upon the rate at which it passed through the flame. During analysis of methylpentadecanoate, detector response increased with scan speed, while at all speeds it was completely removed from the rod. On the other hand, depending upon the amount of cholesterol or phospholipid analyzed, the response either increased, remained unchanged or decreased with scan speed. During a fast scan, detector response was reduced because some material remained on the rod. Thus, the detector response is influenced by sample volatility. In conclusion, there appears to be a complex relationship between detector response and the amount of heat available per microgram of sample. Since we could not find a direct correlation between detector response and sample quantity, it would be difficult to use TLC-FID as a tool for quantitating the components of a lipid mixture.

Cholesterol↗
PubMed1983

Severe fatty liver in rats fed a fat-free ethanol diet, and its prevention by small amounts of dietary arachidonate.

Rats were fed ethanol and a fat-free diet for 30 days to determine whether dietary fat is needed for the development of fatty liver. The severity of fatty liver was similar to that of rats fed an isocaloric diet with 35% fat. Small amounts (29 mg/day) of dietary arachidonic acid prevented alcoholic fatty liver. Rats fed either the alcohol (AF) or control (CF) fat-free diets developed essential fatty acid deficiency (EFAD) as measured by the triene/tetraene ratio of liver and plasma lipids. Rats fed arachidonic acid (AA, alcohol and CA, control diets) did not develop EFAD. Although EFAD alone did not cause the development of fatty liver, the combination of dietary ethanol and EFAD did. The ratios of 16:1/16:0 and 18:1/18:0 in liver lipids indicated that desaturase enzymes were less active and lipogenesis was reduced in rats fed the AA diet compared to those fed the AF diet. In contrast, stimulated lipogenesis appears to have been the cause of fatty liver in rats fed the AF diet.

Animals↗
PubMed1983

Reduction of hepatic stearoyl-CoA desaturase activity in rats fed iron-deficient diets.

The effect of feeding iron-deficient diets to rats on the hepatic stearoyl-CoA desaturase activity was examined since iron is present in the delta 9 desaturation system. Separate groups of rats were fed low iron diets without fat (FF-Fe) or containing either 14% hydrogenated coconut oil (HCNO-Fe) or 14% corn oil (CO-Fe) for 10 weeks. Diets supplemented with iron (FF + Fe, HCNO + Fe and CO + Fe) were fed to the corresponding control groups. Stearoyl-CoA desaturase activity in the liver microsomes of rats in the CO + Fe group (2.55 +/- 0.17 nmol oleate produced/min/mg protein) was about half of that in the HCNO + Fe (4.76 +/- 0.15) and FF + Fe (5.38 +/- 0.18) diet groups. In rats which were fed iron-deficient diets, hepatic desaturase levels were reduced significantly as compared to those of controls (1.0 +/- 0.06, CO-Fe; 2.11 +/- 0.13, HCNO-Fe; 3.65 +/- 0.1, FF-Fe). The hemoglobin (Hb) and hematocrit (Hct) levels in blood showed moderate iron depletion only in the CO-Fe group. Hence, dietary polyunsaturated fat promotes the onset of iron deficiency. Furthermore, even before the blood Hb and Hct values express iron depletion, the effect of feeding low iron diets was observed by the reduction of hepatic delta 9 desaturase activity in rats fed HCNO-Fe and FF-Fe diets.

Animals↗
PubMed1983

Morphology and fatty acid composition of erythrocytes from monkeys exposed to ozone for one year.

Monkeys (Macaca radiata) were exposed to a low dose (0.64 ppm) of ozone (O3) for 8 hr each day over a 1-year period. Control monkeys were exposed to filtered air. The morphology of the red blood cell (RBC) from these monkeys was analyzed by scanning electron microscopy. Red cells from control monkeys had normal morphology with 69% having biconcave shape (discocytes). In O3-exposed animals, blood contained only 35% discocytes. Knizocytes, stomatocytes, and spherocytes each have defined shape which are different from discocytes. The number of knizocytes and stomatocytes in O3-exposed monkeys was twice that of controls. In addition, significant levels of spherocytes were observed while they were absent in the blood of controls. The fatty acid composition of RBC from control and O3-exposed monkeys was the same. These were similar to that of human RBC. However, earlier reports of monkey RBC fatty acid composition differ from our results. These differences are discussed. We conclude that low-dose O3 exposure changes the morphology, but not the fatty acid composition, of erythrocytes in vivo.

Animals↗
PubMed1983

Extent of retention of 2-monoglyceride backbone of diet fat in alcohol-induced fatty liver.

This study was carried out to determine whether hepatic triglyceride (TG) synthesis is a major determinant in the development of fatty liver induced by chronic ethanol ingestion. For this purpose, the degree to which the 2-monoglyceride (MG) backbone of dietary fat was retained in the accumulated TG of fatty liver was examined. Triglycerides were isolated from diet and from the liver and plasma of rats maintained for four weeks on a Lieber-DeCarli liquid ethanol diet. Pancreatic lipase hydrolysis of the TG from these three sources was carried out and the MG produced was analyzed for the fatty acid composition. Almost all of TG in fatty liver and that released to plasma retained the MG structure which originated from diet fat. This result demonstrates that the de novo glyceride synthesis or transacylation reactions do not have a major role in the production of TG in alcohol-induced fatty liver.

Animals↗
PubMed1982

Morphology and fatty acid composition of reticulocytes from phenylhydrazine-treated rats.

Reticulocytosis was induced in rats by injecting phenylhydrazine, a potent oxidizing agent. Red cell morphology was analyzed by scanning electron microscopy. The majority of red cells from rats given injections of phenylhydrazine were types 2 and 3 echinocytes. Stomatocytes were also observed, but pitted lobular reticulocytes were not detected. Echinocytes have not previously been observed in reticulocyte populations. In the reticulocytes, the relative levels of 16:1 and 18:1 were significantly greater than in erythrocytes. These differences in monoenoic acids may be due to the presence of endoplasmic reticulum, the site of desaturase activity in reticulocytes. Of all the fatty acids, the polyunsaturates are the most susceptible to attack during peroxidation. However, the polyunsaturated fatty acid composition of reticulocytes was similar both to that of erythrocytes and to reported values of young erythrocytes isolated by density. Therefore, it is unlikely that lipid peroxidation caused the formation of echinocytes.

Animals↗
PubMed1981

Changes in relative levels of linoleate to arachidonate in erythrocyte phosphatidylcholine in rats fed ethanol and arachidonate.

Young male Sprague--Dawley rats were fed ad lib. for 4 weeks a liquid diet containing 34% of the calories as ethanol and 35% as fat (25 wt % linoleate). The ratio of the levels of linoleic acid to arachidonic acid (18:2/20:4) in erythrocyte phosphatidylcholine (PC) from alcohol-fed rats was greater than that from rats fed an isocaloric control diet. The increased 18:2/20:4 ratio in tissue lipids of animals ingesting ethanol is thought to be due to the reduced production of arachidonate from linoleate. In the present study we tested whether dietary arachidonate would mask the effects of alcohol on the 18:2/20:4 ratio in erythrocyte PC. Analysis of the fatty acid composition of erythrocyte PC of rats fed a diet supplemented with arachidonate showed that ethanol feeding did not alter the 18:2/20:4 ratio.

Animals↗
PubMed1980

Dietary arachidonic acid reduces fatty liver, increases diet consumption and weight gain in ethanol-fed rats.

We fed young male Sprague-Dawley rats for 4 wk ad libitum liquid diets containing 34% of the calories as ethanol and 35% as fat with (AA+) and without (AA-) arachidonic acid (20:4). Additional rats in the control groups were fed similar diets made isocaloric with dextrose with (CA+) and without (CA-) 20:4. The liver triglyceride (TG) content of rats in the AA+ group was reduced ca. 3-fold over that of rats in the AA-group. The diet consumption and body wts of rats in the AA+ group were significantly greater than those of rats fed alcohol without the 20:4 supplement (AA-). Also livers from rats in the AA+ group were as large as those from rats in control groups (CA+, CA-) and ca. twice as large as those from rats in the AA-group. The fatty acid composition of liver TG in rats fed the alcohol diet was similar to that of dietary fat. Levels of 20:4 and docosatetraenoic acid (22:4) in liver TG fatty acids from rats fed diets without arachidonate (AA-, CA-) were low (trace to 1.6%). After ingestion of arachidonic acid, 20:4 increased to ca. 10% and 22:4 to ca. 5%. The content of liver phospholipids was higher in livers of rats fed ethanol (AA-) than in those of controls (CA-).

Animals↗
PubMed1980

Preparation of radiolabled tetracosa mono- and dienoic acid methyl esters from rat erythrocyte lipids by thin layer chromatography.

An easy method of obtaining pure fatty acid methyl esters (FAME) of tetracosa mono- and dienoic acids (24:1, 24:2) using thin layer chromatography (TLC) is described. The total lipids isolated from rat erythrocytes were treated with methanolic-NaOH. Sphingomyelin was unaffected by this treatment and was separated from FAME of glycerolipids and cholesterol by TLC. FAME of sphingomyelin were then prepared by acid methanolysis. These esters migrated into 2 distinct bands on TLC. The slow moving band contained FAME of 16:0, 16:1, 18:0, 18:1, 19:0 and 20:0 wheras the fast moving band contained FAME of 22:0, 23:0, 24:0, 24:1 and 24:2. After AgNO3-TLC, the FAME of the fast moving band separated into 3 species; esters of saturated acids, 24:1 and 24:2, respectively. With erythrocyte lipids of rats fed a fat-free diet and injected with 14C-18:1, this method yielded 14C-24:1. From rats injected with 14C-18:2 and maintained on a corn oil diet, 14C-24:2 was obtained.

Animals↗
PubMed1980

Reduction of essential fatty acid deficiency in rat fed a low iron fat free diet.

Young male rats were fed ad libitum for 8 weeks a low iron fat-free (FF-Fe) diet or a fat-free diet supplemented with iron (FF+Fe). The relative levels of 16:1 and 18:1 to 18:0 in the total fatty acids of liver and other tissues (plasma, erythrocytes and intestinal mucosa) were considerably decreased because of a lack of dietary iron. In rats fed the FF-Fe diet, the levels of essential fatty acids (18:2 omega 6 + 20:4 omega 6) in tissues were 2- to 3-fold greater than in the corresponding tissues of rats fed the FF+Fe diet. Eicosatrienoic acid (20:3 omega 9) levels in tissue lipids from rats fed the FF+Fe diet were high (8-16%), whereas they were low (2-5%) in the case of animals fed the FF-Fe diet. The proportion of 20:4 in total fatty acids of tissues was 2- to 3-fold greater in rats fed the FF-Fe diet than when they were fed the FF+Fe diet. Therefore, the relative levels of 20:3 omega 9/20:4 omega 6 varied from 1-2.9 in tissue lipids of rats fed the FF+Fe diet, while it varied only from 0.2-0.3 in animals fed the FF-Fe diet. These results suggest that a lack of dietary iron may reduce the synthesis of 16:1, 18:1, 20:3 and 20:4 and the metabolism of 20:4.

Animals↗
PubMed1980

Enhanced ratio of linoleic acid to arachidonic acid in erythrocyte phosphatidylcholine in rats during withdrawal from ethanol.

Male Sprague-Dawley rats were pair-fed for 8 weeks either an alcohol diet or a control diet made isocaloric with dextrose. Those on the alcohol diet were then fed the control diet for 3 days and both groups were killed. Analysis of the fatty acid composition of the various blood lipids showed that the relative level of 18:2 to 20:4 was significantly greater in the phosphatidylcholine fraction from erythrocytes of rats withdrawn from alcohol as compared to that from control animals. It has been suggested that in alcohol-fed animals the hepatic capacity to produce 20:4 from 18:2 is reduced. Therefore the increase in the ratio of 18:2/20:4 in erythrocyte phosphatidylcholine could serve as an index to detect the liver malfunction and to confirm recent chronic alcohol consumption.

Animals↗