Weeks Of Experimental Diet Research Articles

MARKERS OF INFLAMMATION IN RATS UNDER TOXIC INJURY AGAINST DIETARY PROTEIN DEFICIENCY

The paper presents studies of biomarkers of the development of inflammatory reactions in the blood serum of rats under the conditions of toxic damage with acetaminophen against the background of dietary protein deficiency. The animals consumed a semi-synthetic diet during the experiment according to the recommendations of the American Institute of Nutrition. In order to simulate alimentary protein deprivation, rats received a low-protein diet containing 1/3 of the standard daily protein requirement daily for 28 days. The animals were modeled acute toxic damage with acetaminophen after four weeks of experimental diet. The administration of the toxin was carried out at doses of 1250 mg/kg animal body weight in suspension in 2 % starch gel solution once a day for 2 days by gavage. Determination of the level of C-reactive protein, procalcitonin, tumor necrosis factor-alpha, interleukin-6 in the blood serum of rats was carried out by the method of immunoenzymatic analysis. We have established that toxic damage by the drug xenobiotic - acetaminophen against the background of dietary protein deficiency is accompanied by a maximum increase in the level of C-reactive protein (15.5 times) and procalcitonin (10 times) in the blood serum of rats compared to the control value, which can be considered as prognostic biomarkers of the systemic inflammatory reaction under these experimental conditions. At the same time, under these experimental conditions, hyperproduction of tumor necrosis factor-alpha and interleukin-6 was registered in the blood serum of experimental groups of rats with maximum values when toxic doses of acetaminophen were administered to protein-deficient animals, which is consistent with changes in the level of C-reactive protein and procalcitonin. The fact we found makes it possible to assume that dietary protein deprivation increases the production of TNF-α and IL-6 as pro-inflammatory mediators in toxic liver damage, thus inducing primary damage to liver parenchymal cells..

Effects of phosphorus and calcium to phosphorus consumption ratio on mineral metabolism and cardiometabolic health

Phosphorus is a common additive used in food processing that is typically consumed in excess of the recommended daily allowance; however, our knowledge of its effects on health, in the context of normal renal function, is limited. Unlike phosphorus, calcium intake is generally less than recommended, and it has been hypothesized that the calcium to phosphorus ratio may be partly responsible for the proposed negative health consequences. Therefore, this study sought to determine the effects of increased phosphorus additive intake, in the context of high calcium consumption, on endocrine markers of mineral metabolism and cardiometabolic health. An outpatient feeding study was performed in which healthy adults were fed a run-in control diet for 2 weeks followed by a phosphorus additive enhanced diet with supplemental calcium to an approximate ratio of 1 (experimental diet) for 2 weeks. Blood and urine samples were collected, and participants had brachial flow-mediated dilatation measured, with analyses comparing follow-up measures to baseline. Two weeks of experimental diet increased serum fibroblast growth factor 23 concentrations but lowered body weight and serum leptin; however, other phosphorus responsive factors such as osteopontin and osteocalcin did not increase. A complementary study in male mice also demonstrated that the regulation of known dietary phosphorus responsive factors was mostly abrogated when dietary calcium was raised in parallel with phosphorus. In conclusion, the study identifies weight, leptin and insulin as responsive to dietary phosphorus and that certain aspects of the systemic phosphorus response are attenuated by a corresponding high calcium intake.

Вміст сіалових кислот у плазмі крові щурів за умов ацетамінофен-індукованої гепатотоксичності на тлі аліментарної нестачі протеїну

The work is devoted to the study of the fractional distribution of sialic acids in the blood plasma of rats under the conditions of toxic damage with acetaminophen after alimentary protein deprivation. The content of free, protein-bound and oligo-bound sialic acids in the blood plasma of animals was investigated under experimental conditions. The animals consumed a semi-synthetic diet during the experiment according to the recommendations of the American Institute of Nutrition. In order to simulate alimentary protein deprivation, rats received a low-protein diet containing 1/3 of the standard daily protein requirement daily for 28 days. The animals were modeled acute toxic damage with acetaminophen after four weeks of experimental diet. The administration of the toxin was carried out at doses of 1250 mg/kg animal body weight in suspension in 2 % starch gel solution once a day for 2 days by gavage. The concentration of free, protein- and oligo-bound sialic acids was determined spectrophotometrically at 549 nm by color reaction with thiobarbituric acid. Removal of non-sialic acid specific chromogens were performed by the addition of n-butanol. It has been shown that the increase of total sialic acids in the blood plasma of protein-deficient rats (by 40% compared to control) is due only to the increase in the level of the oligo-bound fraction. Thus, protein deficiency is a key factor in the established changes, which probably indicates the intensification of catabolism processes of intracellular easily mobilized proteins under the conditions of protein deficiency in the diet. At the same time, toxin (acetaminophen) intake, leads to an increase in the concentration of total sialic acids, mainly due to the increase of free and protein-bound fractions, which indicates the development of inflammatory processes in the tissues of the body, regardless of the amount of exogenous protein consumed.

Effects of chronic intake of starch-, glucose- and fructose-containing diets on eating behaviour in adult minipigs

IntroductionThe aim of this study was to assess whether chronic intake of isocaloric high-fat diets differing partly in the source of carbohydrates (starch, glucose or fructose) and fed at the same level of intake impacts eating behaviour in the adult Yucatan minipig. MethodsAdult minipigs were offered for 8 weeks either of three high-fat diets in which 20% of dry matter weight (36.3% of metabolizable energy) was provided as pure maize starch (SD), glucose (GD) or fructose (FD) (n=5 per diet). Three eating behaviour tests, including a three-feed choice test, an eating microstructure test and operant conditioning with progressive ratio test were performed before and after dietary treatment in order to evaluate the impact of these carbohydrates on feed preferences and animal's motivation. ResultsAfter 8-week treatment, all groups had similar increases in body weight (from 36.2±1.2 to 57.5±0.1kg, P<0.0001). Animals showed initial preference and higher motivation for the GD over the SD, FD being intermediate. Importantly, only pigs chronically fed the FD developed a large preference for this diet: increase in FD intake (from 15±3 to 35±6g/kg0.75, P<0.05). After 8 weeks of experimental diets, intake speed of FD (19±6g/min) was higher compared to GD and SD (P=0.001). ConclusionOur data indicate that chronic intake of diets differing in a part of the carbohydrate source induced substantial weight gain, regardless of the carbohydrate source. Pigs’ initial preference and higher motivation was for the GD, compared to SD and FD. Intake of the fructose-containing diet for 8 weeks induced a stronger preference for this diet. Our data may have important implications in terms of impact of prolonged fructose consumption on eating behaviour in humans.

Abstract 135: Evaluation of the Effects of Glimepiride (Amaryl) and Repaglinide (Novonorm) on Atherosclerosis Progression in High Cholesterol-Fed Male Rabbits

Atherosclerosis is an inflammatory disease of the blood vessel wall, characterized in early stages by endothelial dysfunction, recruitment and activation of monocyte/macrophages. Glimepiride is one of the third generation sulphonylurea drugs useful for control of diabetes mellitus type two and it may exert anti inflammatory activity by induction of nitric oxide production or through selective suppression of the cyclooxygenase pathway . Repaglinide is a new hypoglycemic agent, a member of the carbamoylmethyl benzoic acid family. Some results from the literature demonstrate that repaglinide has a favorable effect on the parameters of antioxidative balance. Objectives: The objective of present study was to assess the effect of glimepiride and repaglinide on atherosclerosis via interfering with inflammatory and oxidative pathways. Methods: twenty four local domestic male rabbits were involved in this study. The animals were randomly divided into four groups; Group I rabbits fed normal chow (oxiod) diet for 10 weeks. Group II rabbits fed with 1% cholesterol enriched diet. Group III rabbits fed with 1% cholesterol enriched diet together with Glimepiride (0.1mg/kg once daily before morning feed). Group IV rabbits fed with 1% cholesterol enriched diet together with Repaglinide (0.3mg/kg once daily before morning feed). Blood samples were collected before (0 time) and every two weeks of experimental diets for measurement of serum triglycerides (TG), total cholesterol (TC), HDL-C, high sensitive C - reactive protein (hsCRP), IL-6 and TNF-α level. At the end of 10weeks the aorta was removed for measurement of aortic Malondialdehyde (MDA), reduced glutathione (GSH) and aortic intimal thickness. Results: Glimepiride and repaglinide treatment did show significant effect on lipid parameters compared with induced untreated group ( P &gt; 0.05).Also they were significantly reduced the elevation in hsCRP, IL-6, TNF-α, aortic MDA and aortic intimal thickness compared with induced untreated group ( P &lt; 0.05),and they restore aortic GSH level ( P &lt; 0.05) . Conclusions: Glimepiride and repaglinide may reduce atherosclerosis progression in hypercholesterolemic rabbit via interfering with inflammatory and oxidative pathways without affecting lipid parameters.

Evaluation of the effects of glimepiride (Amaryl) and repaglinide (novoNorm) on atherosclerosis progression in high cholesterol-fed male rabbits

Background:Atherosclerosis is an inflammatory disease of the blood vessel wall, characterized in early stages by endothelial dysfunction, recruitment and activation of monocyte/macrophages. Glimepiride is one of the third generation sulphonylurea drugs, useful for control of diabetes mellitus type two and it may exert anti inflammatory activity, by induction of nitric oxide production or through selective suppression of the cyclooxygenase pathway. Repaglinide is a new hypoglycemic agent, and a member of the carbamoylmethyl benzoic acid family. Some results from the literature demonstrate that repaglinide has favorable effects on the parameters of antioxidative balance.Objectives:The objective of the present study was to assess the effect of glimepiride and repaglinide on atherosclerosis via interfering with the inflammatory and oxidative pathways.Materials and Methods:Twenty four local domestic male rabbits were involved in this study. The animals were randomly divided into four groups; Group I rabbits fed normal chow (oxiod) diet for 10 weeks. Group II rabbits were fed with 1% cholesterol enriched diet. Group III rabbits were fed with 1% cholesterol enriched diet together with Glimepiride (0.1 mg/kg once daily before morning feed). Group IV rabbits were fed with 1% cholesterol enriched diet together with Repaglinide (0.3 mg/kg once daily before morning feed). Blood samples were collected before (0 time) and every two weeks of experimental diets for measurement of serum triglycerides (TG), total cholesterol (TC), High-density lipoprotein cholesterol (HDL-C), high sensitive C - reactive protein (hsCRP), Interleukin – 6 (IL-6) and Tumor Necrosis Factor alpha (TNF-α) levels. At the end of 10 weeks, the aorta was removed for measurement of aortic Malondialdehyde (MDA), reduced glutathione (GSH) and aortic intimal thickness.Results:Glimepiride and repaglinide treatment did show significant effect on lipid parameters compared with induced untreated group (P < 0.05). Also, they significantly reduced the elevation in hsCRP, IL-6, TNF-α, aortic MDA and aortic intimal thickness compared with induced untreated group (P < 0.05), and they helped to restore the aortic GSH levels (P < 0.05).Conclusions:Glimepiride and repaglinide may reduce atherosclerosis progression in hypercholesterolemic rabbits by interfering with the inflammatory and oxidative pathways without affecting lipid parameters.

Reduces cholesterol induced atherosclerotic lesions in aorta artery in hypercholesterolemic rabbits

Atherosclerosis is the leading cause of death in developed countries with many proved risk factors. Vinegar has been proved to have some medical uses and some potential protective effects on atherosclerosis. In this study, effects of vinegar on various risk factors of atherosclerosis and development of atherosclerosis in hypercholesterolemic rabbit have investigated. Rabbits were assigned to four groups and each group received one of experimental diets: normal diet, high cholesterol diet (1% cholesterol), 1% cholesterol supplemented with 5 ml vinegar and 1% cholesterol supplemented with 10 ml vinegar for 8 weeks. Blood samples were collected before and after 8 weeks of experimental diets for measurement of serum C-reactive protein (CRP), nitrite, nitrate, apolipoprotein A (ApoA 1) and apolipoprotein B (ApoB 100 ), total cholesterol (TC), fibrinogen and factor VII. At the end of study, fatty streak formation in aorta was determined in all groups. Using vinegar (5 and 10 ml) with hypercholesterolemic diet caused significant reduction in CRP, fibrinogen, factor VII, ApoB 100 , ApoB/ApoA ratio, TC levels, atherosclerotic lesions in aorta and increased nitrite and nitrate in comparison with hypercholesterolemic diet. Vinegar did not significantly change ApoA 1 level compared to high cholesterol diet. These results suggest that vinegar reduced atherosclerosis processes in high cholesterol diet fed animals. More studies are needed to find the exact mechanisms of action.

Effects of flaxseed oil on serum lipids and atherosclerosis in hypercholesterolemic rabbits.

Flaxseed oil has very high content of alpha-linolenic acid (C18:3n-3, omega-3 [n-3] fatty acid). Based on the usefulness of n-3 fatty acid in fish oil against cardiovascular diseases, flaxseed oil is marketed as a health food. The n-3 fatty acid in flaxseed oil is different than that of fish oil. Indirect evidence suggests that the omega-3 fatty acid in flaxseed oil is not effective in lowering serum lipids and hypercholesterolemic atherosclerosis. The effects of flaxseed oil on serum lipids and hypercholesterolemic atherosclerosis are not known. An investigation, therefore, was made of flaxseed oil on high-cholesterol diet-induced atherosclerosis, serum lipids (triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, risk ratio of total cholesterol to high-density lipoprotein cholesterol), serum and aortic malondialdehyde, an index of levels of reactive oxygen species, aortic chemiluminescence (a measure of antioxidant reserve), and reactive oxygen species-producing activity of white blood cell chemiluminescence in rabbits. The rabbits were assigned to four groups: Group I, regular diet (control); Group II, 5% flaxseed oil in regular diet; Group III, 0.5% cholesterol diet; Group IV, diet containing 0.5% cholesterol and 5% flaxseed oil. Blood samples were collected before and after 4 and 8 weeks of experimental diets for measurement of serum lipids, serum malondialdehyde, and white blood cell chemiluminescence. At the end of 8 weeks of the experimental diet, aortas were removed for measurement of atherosclerotic plaques, aortic malondialdehyde, and antioxidant reserve. Serum total cholesterol, triglycerides, and low-density and high-density lipoprotein cholesterol, and risk ratio of total cholesterol to high-density lipoprotein cholesterol, were elevated to a similar extent in Groups III and IV compared to Groups I and II. The extent of atherosclerosis in Groups III and IV was similar (56.74% +/- 11.14% vs 58.01% +/- 10.95%). Groups III and IV both had similar increases in serum and aortic malondialdehyde and antioxidant reserve. Reactive oxygen species-producing activity of white blood cells increased in Group III, and flaxseed oil prevented the cholesterol-induced increase in white blood cell chemiluminescence in Group IV. These results suggest that flaxseed oil does not produce an alteration in serum lipids or in the extent of hypercholesterolemic atherosclerosis; however, it decreases white blood cell chemiluminescence. The ineffectiveness of flaxseed oil was associated with its ineffectiveness in altering the levels of oxidative stress.

Hypolipidemic Properties of Fermented Capsicum and Its Product

This study was conducted to investigate the effects of fermented capsicum and a capsicum product on lipid metabolism. Fermented capsicum was prepared from red pepper puree for three months. After 90 days of fermentation, capsaicin and dihydrocapsaicin concentrations were reduced from 24.7 and 14.7 g/mL to 15.5 and 6.45 g/mL, respectively. The capsicum product was prepared from the fermented capsicum mixed with prune extract, green tea extract, neroli extract and oligo-saccharide. Thirty-two male Sprague-Dawley rats were assigned to four dietary groups (control, high-fat control (HF-control), high-fat-fermented capsicum (HF-S-1), highfat- capsicum product (HF-S-2)). Plasma and hepatic lipid profiles were examined after three weeks of experimental diet. Food intakes were significantly lower in the HF-S-1 and HF-S-2 groups compared to the control group (p＜0.05). The weight of perirenal fat pads was lowest in animals on the control diet (low-fat) and highest in high-fat control diet. The addition of fermented capsicum to high fat diets, HF-S-1 and HF-S-2 groups, resulted in significantly lower fat pad weights compared with the HF-control group. Both fermented capsicum (HF-S-1) and the capsicum product (HF-S-2) groups had lower plasma TG levels, atherogenic-index, and liver TG levels than the HF-control group (p＜0.05). Liver TC levels were significantly lower in the HF-S-2 group than the HF-control group. The results demonstrate a hypolipidemic effect of fermented capsicum and the fermented capsicum product.

Effect of vitamin E supplementation on antibody levels against malondialdehyde modified LDL in hyperlipidemic hamsters.

The aim of this work was to investigate the effect of vitamin E (VE) supplementation on the formation of autoantibodies against oxidized low density lipoproteins (LDL) in a hyperlipidemic animal model. Thirty-four male hamsters (Mesocricetus auratus), (4 weeks old) were divided into three groups: Group A (n=9) was fed with standard rodent chow; group B (n=13) was fed with a standard rodent chow plus 2% cholesterol and 10% butter and group C (n=12) was fed with the same diet plus 0.2% (w/w) VE. Blood samples were collected by intracardiac puncture and antibody levels were determined in each animal at 4 weeks of age and after 20 weeks of experimental diet. A modified ELISA technique was used to analyze the modulation of autoantibody titers against an epitope of oxidized LDL in serum samples. Antigens prepared for the ELISA tests were characterized using spectrofluorimetry. Serum VE levels were determined in the lipidic fractions by HPLC. The groups fed with cholesterol-fat enriched diet presented a three-fold increase in total serum cholesterol and two-fold increase in serum triglycerides compared to the control group. VE supplementation played no role in serum cholesterol and serum triglyceride concentrations but led to a decreased autoantibody (anti-LDL-malondialdehyde) formation (P<0.05). Our results show that VE supplementation leads to a lower production of autoantibodies against oxidized LDL, suggesting a protective effect of VE against in vivo oxidation of LDL particles, in a dose-dependent manner.

Effect of roxarsone inclusion in the diet on the performance and hepatic lipid metabolism of laying Tsaiya duck

1. The aim of this study was to examine the effects of roxarsone (3-nitro-4-hydroxyphenylarsonic acid) inclusion in the diet on the performance, liver function and lipid metabolism in the liver of laying Brown Tsaiya ducks. 2. Sixty 36-week-old laying ducks were selected and allocated at random into 4 dietary treatments with 3 replications for each treatment. Feeding was for 7 weeks with 3 weeks of experimental diets followed by a 4 week withdrawal period. The experimental diets were supplemented with 0, 50, 100 and 300 mg/kg roxarsone, respectively. 3. Dietary inclusion of 50 or 100 mg/kg roxarsone did not significantly promote performance. Inclusion of 300 mg/kg significantly depressed ( P <0.05) performance, liver weight and content, serum triacylglycerol (TG), serum nonesterified fatty acid (NEFA) and increased ( P <0.05) cholesterol, creatine kinase (CK) and aspartate aminotransferase (AST) in the serum at the end of 3 weeks on the experimental diet. 4. Laying characteristics returned to normal 4 weeks after withdrawal of roxarsone. The liver weight, fat and TG in the liver and serum concentrations of TG, NEFA, high density lipoprotein (HDL) and AST increased significantly ( P <0.05), while the level of very low density lipoprotein (VLDL) decreased ( P <0.05) at the end of the withdrawal period. More prominent vacuolised hepatic fatty cells were observed in laying ducks treated with 300 mg/kg of roxarsone.

Reduction of serum cholesterol and hypercholesterolemic atherosclerosis in rabbits by secoisolariciresinol diglucoside isolated from flaxseed.

Secoisolariciresinol diglucoside (SDG) is a plant lignan isolated from flaxseed. Lignans are platelet-activating factor-receptor antagonists that would inhibit the production of oxygen radicals by polymorphonuclear leukocytes. SDG is an antioxidant. Antioxidants studied thus far are known to reduce hypercholesterolemic atherosclerosis. The objective of this study was to determine the effect of SDG on various blood lipid and aortic tissue oxidative stress parameters and on the development of atherosclerosis in rabbits fed a high-cholesterol diet. Rabbits were assigned to 4 groups: group 1, control; group 2, SDG control (15 mg. kg body wt-1. d-1 PO); group 3, 1% cholesterol diet; and group 4, same as group 3 but with added SDG (15 mg. kg body wt-1. d-1 PO). Blood samples were collected before (time 0) and after 4 and 8 weeks of experimental diets for measurement of serum triglycerides, total cholesterol (TC), and LDL, HDL, and VLDL cholesterol (LDL-C, HDL-C, and VLDL-C). The aorta was removed at the end of the protocol for assessment of atherosclerotic plaques; malondialdehyde, an aortic tissue lipid peroxidation product; and aortic tissue chemiluminescence, a marker for antioxidant reserve. Serum TC, LDL-C, and the ratios LDL-C/HDL-C and TC/HDL-C increased in groups 3 and 4 compared with time 0, the increase being smaller in group 4 than in group 3. Serum HDL-C decreased in group 3 and increased in group 4 compared with time 0, but changes were lower in group 3 than in group 4. SDG reduced TC and LDL-C by 33% and 35%, respectively, at week 8 but increased HDL-C significantly, by>140%, as early as week 4. It also decreased TC/LDL-C and LDL-C/HDL-C ratios by approximately 64%. There was an increase in aortic malondialdehyde and chemiluminescence in group 3, and they were lower in group 4 than in group 3. SDG reduced hypercholesterolemic atherosclerosis by 73%. These results suggest that SDG reduced hypercholesterolemic atherosclerosis and that this effect was associated with a decrease in serum cholesterol, LDL-C, and lipid peroxidation product and an increase in HDL-C and antioxidant reserve.

Reduction of hypercholesterolemic atherosclerosis by CDC-flaxseed with very low alpha-linolenic acid

Flaxseed (Type I flaxseed) with 51–55% α-linolenic acid in its oil and richest source of plant lignans, has been shown to reduce hypercholesterolemic atherosclerosis by 46% without lowering serum lipids. Antiatherogenic activity was claimed to be due to its α-linolenic acid and/or lignan content. If α-linolenic acid component of flaxseed is responsible for antiatherogenic activity, then, CDC-flaxseed (Type II flaxseed) which has similar oil and lignan content but has very little (2–3% of the total oil) α-linolenic acid would have no antiatherogenic effect. An investigation, therefore, was made of Type II flaxseed on high cholesterol diet-induced atherosclerosis and serum lipids [total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C)] in rabbits. Rabbits were assigned to four groups: Group I, Control; Group II, Type II flaxseed diet (7.5 g/kg orally daily); Group III, 1% cholesterol diet; Group IV, 1% cholesterol diet supplemented with Type II flaxseed (7.5 g/kg orally daily). Blood samples were collected before (0 time) and after 4 and 8 weeks of experimental diets for measurement of serum lipids. Aorta was removed at the end of 8 weeks for assessment of atherosclerotic plaques. Serum TC, LDL-C, TC/HDL-C, and LDL-C/HDL-C were lower in Group IV as compared to Group III by 14 and 31%, 17 and 32%, 28 and 34% and 24 and 32%, respectively, at 4 and 8 weeks. HDL-C was not affected by Type II flaxseed in hypercholesterolemic rabbit. TG and VLDL-C were markedly increased in Group IV as compared to Group III. Type II flaxseed reduced the development of atherosclerosis by 69%. Histological changes in the atherosclerotic regions were qualitatively similar in Groups III and IV. Results indicate that reduction in hypercholesterolemic atherosclerosis by Type II flaxseed is due to a decrease in serum TC and LDL-C. In conclusion, antiatherogenic activity of Type II flaxseed is not due to α-linolenic acid.

Prevention of Hypercholesterolemic Atherosclerosis by Garlic, an Antixoidant.

BACKGROUND: Investigations of the effects of high cholesterol diet in the presence and absence of garlic on the genesis of atherosclerosis, the blood lipid profile, aortic tissue lipid peroxidation product malondialdehyde, chemiluminescence, a marker for antioxidant reserve and activity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase were made in rabbits. METHODS AND RESULTS: Four groups of 10 rabbits each were studied: group 1 was given regular rabbit chow, group 2 was given rabbit chow diet supplemented with garlic powder (300 mg twice daily orally), group 3 was given 1% cholesterol diet, group 4 was given 1% cholesterol diet supplemented with garlic powder (300 mg twice daily orally). Blood concentration of triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol were measured before and after 4 and 10 weeks of experimental diets. The aorta was removed at the end of protocol (10 weeks) for assessment of atherosclerotic changes (gross and microscopic), malondialdehyde concentration, chemiluminescence, and activity of antioxidant enzymes. Total cholesterol, low density-lipoprotein cholesterol and ratio of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol and ratio of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol increaserd in group 3 and 4; the increase was smaller in group 4 than in in group 3 although not significant. Serum high-density lipoprotein cholesterol decreased to a similar extent in groups 3 and 4. Serum triglyceride and very low-density lipoprotein cholesterol remained unchanged in group 3 but increased in group 4. These values were significantly higher than those in group 1. Garlic in rabbits with control diet decreased the levels of triglyceride and very low density lipoprotein but did not affect the levels of total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol and the ratio of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol. There was an increase in aortic tissue malondialdehyde, chemiluminescence, and activities of catalase and glutathione peroxidase in group 3 compared with those in group 1. Levels of aortic malondialdehyde, chemiluminescence, catalase, and glutathione peroxidase were lower in group 4 compared with group 3; however, values for malondialdehyde and chemiluminescence were lower and that of catalase and glutathione peroxidase were higher in group 4 compared with group 1. Superoxide dismutase activity was similar in all the four groups. Malondialdehyde, chemiluminescence, and activity of catalase of aortic tissue decreased while activity of glutathione peroxidase increased in group 2. Atherosclerotic changes were lower in group 4 compared with group 3. Histologic changes were practically similar in groups 3 and 4. CONCLUSIONS: Increased levels of malondialdehyde, chemiluminescence, and antioxidant enzymes associated with development of atherosclerosis suggests a role for oxygen free radicals in the pathogenesis of hypercholesterolemic atherosclerosis. The protection afforded by garlic was associated with decrease in aortic malondialdehyde and chemiluminescence inspite of no change in serum cholesterol. These findings suggest that oxygen free radicals are involved in the genesis and maintenance of hypercholesterolemic atherosclerosis and that use of garlic can be useful in preventing the development of hypercholesterolemic atherosclerosis.

Cell proliferation and esophageal carcinogenesis in the zinc-deficient rat

Target cell proliferation was investigated throughout the development of esophageal cancer induced by N-nitroso-methylbenzylamine (NMBA) in weanling rats maintained on zinc-deficient or sufficient diets. Deficient rats were fed ad libitum, while zinc-sufficient rats were either pair-fed to the deficient animals or fed ad libitum. After 5 weeks, half of the animals in each dietary group were given six intragastric doses of NMBA (2 mg/kg; twice weekly). The remaining rats were untreated by carcinogen. At weeks 1, 2, 3, 4, 5, 7, 9 and 11 post first dose, esophageal cell proliferation was assessed in rats from each group by in vivo bromodeoxyuridine (BrDU) labeling followed by immunohistochemical detection of cells in S-phase. At 11 weeks, the tumor incidence was 100, 23 and 6%, respectively, in the zinc-deficient, zinc-sufficient, ad libitum and pair-fed groups. In vivo BrDU labeling revealed that in the NMBA-untreated groups, the labeling index (LI), the number of labeled cells, and the total number of cells per cross section of entire esophagi were significantly increased by zinc deficiency at all time points; LI was lowest in zinc-sufficient, pair-fed rats. During NMBA treatment (weeks 6, 7 and 8), increased cell proliferation occurred in both groups of zinc-sufficient esophagi but only during week 6 in the deficient ones. In the weeks following the cessation of NMBA treatment, zinc-deficient esophagi showed significantly increased LI and greater number of labeled cells than the carcinogen treated, zinc-sufficient pair-fed or ad libitum fed groups. On the other hand, NMBA-treated zinc-sufficient pair-fed rats showed lower LI and smaller number of labeled cells than their zinc-sufficient ad libitum counterparts. Most importantly, esophageal papillomas were found in two zinc-deficient animals that had received no NMBA treatment, after 10-11 weeks of experimental diet. These data support a direct relationship between cell proliferation and tumor incidence, and also provide evidence that zinc deficiency and its associated cell proliferation could be carcinogenic.

Swine and experimental atherosclerosis.

1) Addition of butter to the diet of swine caused a significant elevation in serum cholesterol levels. This did not occur in other animals fed isocaloric quantities of corn oil. The increase in cholesterol was limited to the high-density (alpha) lipoproteins. 2) Necropsy after 9 weeks of experimental diets revealed lesions somewhat resembling human atheromata in 50% of aortae. The same incidence was found in control animals on a conventional diet.