Effect of maternal diet rich in omega‐6 and omega‐9 fatty acids on the liver of LDL receptor‐deficient mouse offspring

BACKGROUND: Omega‐6 fatty acids are important to fetal development. However, during gestation/lactation, these fatty acids may contribute toward the development of fat tissue. Omega‐9 fatty acids are associated with a reduction in serum lipids and protection from liver disease. OBJECTIVES: The present study investigated the effect of the maternal intake of omega‐6 and omega‐9 in hypercholesterolemic mothers on the liver of the offspring. METHODS: LDL receptor–deficient mice were fed a diet rich in either omega‐6 (E6D) or omega‐9 (E9D) for 45 days prior to mating and until the birth of the offspring, evaluating the effect on the offspring liver in comparison to a standard diet (STD). RESULTS: Mothers fed with the E6D experienced an increase in total cholesterol (TC) and the offspring exhibited an increase in TC, hepatic triglycerides (TG), and CC‐chemokine ligand (CCL)2/monocyte chemoattractant protein (MCP)‐1 as well as a reduction in HDL. Histological analysis on this group revealed steatosis, leukocyte infiltrate, and increased CCL2/MCP‐1 expression. The ultrastructural analysis revealed hepatocytes with lipid droplets and myofibroblasts. The offspring of mothers fed the standard diet exhibited low serum TC, but microvesicular steatosis was observed. The offspring of mothers fed the E9D exhibited lower serum and hepatic TG as well as higher LDL in comparison to the other diets. The histological analyses revealed lower steatosis and leukocyte infiltrate. CONCLUSIONS: The findings suggest that hypercholesterolemic mothers with a diet rich in omega‐6 fatty acids predispose their offspring to steatohepatitis, whereas a diet rich in omega‐9 has a protective effect. Birth Defects Res (Part B) 89:164–170, 2010. © 2010 Wiley‐Liss, Inc.     

The dynamics of infection of Diphyllobothrium dendriticum (Nitzsch) and D. ditremum (Creplin) in the char Salvelinus alpinus (L.) in Sweden

A total of 654 char, Salvelinus alpinus (L.), from Lake Bjellojaure, Sweden, were examined for plerocercoids of Diphyllobothrium dendriticum (Nitzsch, 1824) and D. ditremum (Creplin, 1825) from September 1969 to December 1974. Plankton samples showed that the dominating copepod species in the lake were Eudiaptomus graciloides (Lilljeborg), Cyclops scutifer Sars and Heterocope appendiculata Sars. E. graciloides passed the winter as adults and C. scutifer as copepodids while H. appendiculata was restricted to a short period in the summer. Copepods occurred in the stomachs in September-October and to a certain extent in April-May, but only cyclopids and Heterocope sp. were found. C. scutifer is proposed to be the main first intermediate host of both D. dendriticum and D. ditremum . The potential final hosts were thecommon gull, Larus canus L., for D. dendriticum and the black-throated diver, Gavia arctica (L.), for D. ditremum . One common gull was experimentally successfully infected with plerocercoids of D. dendriticum . The parasites showed no seasonal cycle in incidence of infection.     

Effects of postnatal age and diet on the fatty acid composition of plasma lipid fractions in preterm infants

Diet and postnatal age effect the fatty acid composition of plasma and tissue lipids. This work was designed as a transversal study to evaluate the changes in the fatty acid composition of plasma phospholipids, cholesteryl esters, triglycerides and free fatty acids in preterm infants (28-35 weeks gestational age), fed human milk (HM) and milk formula (MF) from birth to 1 month of life. Sixteen blood samples were obtained from cord, and 19 at 6-8 h after birth, 14 at 1 week and 9 at 4 weeks from HM-fed infants and 18 at 1 week and 14 at 4 weeks from MF-fed ones. Groups had similar mean birth weight, gestational age and sex ratio. The MF provided 69 kcal/dl and contained 16% of linoleic acid and 1.3% of alpha-linolenic acid on the total fat. Plasma lipid fractions were extracted and separated by thin-layer chromatography and fatty acid methyl esters were quantitated by gas liquid chromatography. In plasma phospholipids, linoleic acid (18:2 omega 6) continuously increased from birth to 1 month of age, but no changes were seen as related to type of diet; polyunsaturated fatty acids greater than 18 carbon atoms of both the omega 6 and omega 3 series (PUFA omega 6 greater than 18 C and omega 3 greater than 18 C) dropped from birth to 1 week and continued to decrease in MF-fed infants until 1 month; eicosatrienoic (20:3 omega 6), arachidonic (20:4 omega 6) and docosahexaenoic (22:6 omega 3) were the fatty acids implicated. In cholesteryl esters palmitoleic (16:1 omega 7) and oleic (18:1 omega 9) acids decreased from birth to 1 month and linoleic acid increased and arachidonic acid dropped, especially in MF fed infants. In triglycerides, palmitic, palmitoleic and stearic acid (18:0) decreased during the first month of life; oleic acid remained constant and linoleic acid increased in all infants, but arachidonic acid decreased only in those fed formula. Free fatty acids showed a similar behavior in fatty acids and in plasma triglycerides. Preterm neonates seem to have special requirements of long-chain PUFA and adapted MF should contain these fatty acids in similar amounts to those of HM to allow the maintenance of an adequate tissue structure and physiology.     

Metazoan parasite community structure of sea trout on the west coast of Ireland

A total of 129 sea trout smolts from 10 locations on the west coast of Ireland were examined for metazoan parasites. Of 11 species identified only four had a prevalence >20%. Two species Hysterothylacium aduncum and Hemiuris communis have a confirmed marine origin; Eubothrium crassum has been shown to exist in both the sea and fresh water. The remaining species were fresh water. Overall the parasite community was dominated by autogenic species with only Diphyllobothrium dendriticum having allogenic transmission. Infracommunity values for mean species richness, and Brillouins index of diversity were low, indicating the presence of an impoverished helminth community with little potential for interspecific interaction. The relationship between marine helminths and sea lice was also examined.     

我国牛羊双腔类吸虫的继续研究:Ⅲ.三种双腔吸虫后蚴在异常昆虫宿主蚂蚁体内的发育

内蒙科尔沁草原的中华双腔吸虫(Dicrocoelium chinensis Tang et Tang,1978)其第二中间宿主是黑玉蚂蚁(Formica gagates),而山东滨州地区的矛形双腔吸虫(D.lanceatum Rud.,1803)和枝双腔吸虫(D.dendriticum Rud.,1819)的蚂蚁宿主是中华蚂蚁(Formica sinica)。作者用中华双腔吸虫的黏球感染山东的中华蚂蚁,同时用矛形双腔和枝双腔的黏球分别感染内蒙的黑玉蚂蚁。本文报道此试验中不同蚂蚁种类和各虫种后蚴间所产生的不同反应情况,及矛形双腔和枝双腔在后蚴各发育期的形态差异。     

Isoenzymes of lactate dehydrogenase (EC 1.1.1.27) in Dicrocoelium dendriticum and Fasciola hepatica (Trematoda)

The isoenzymes of LDH (EC 1.1.1.27) were studied in Dicrocoelium dendriticum and Fasciola hepatica by horizontal electrophoresis on polyacrylamide gel. Six isoenzymes in D. dendriticum and four in F. hepatica were detected. Densitometric scans demonstrated that the enzyme pattern of LDH in D. dendriticum parasitizing hepatic tissue of Capra hircus was clearly different from the one obtained when the trematode parasitized other hosts such as Bos taurus or Ovis aries.     

A comparative study of the egg morphology in four species of Eubothrium (Cestoda: Pseudophyllidea) with comments on their early development

Abstract. Freshly released eggs from four species of the cestode Eubothrium ( Eubothrium crassum, Eubothrium fragile, Eubothrium rugosum , and Eubothrium salvelini ) were subjected to morphological and morphometric analysis. The eggs of the two freshwater species, E. rugosum and E. salvelini , were ovoid with a lobed embryophore whereas the eggs of the two marine species, E. crassum and E. fragile , were more circular with a smooth embryophore. However, the morphological differences between species were not readily evident to permit their clear distinction from one another. To discriminate species, a forward stepwise linear discriminant analysis, using six of the seven measured metric characters made on the eggs, was used, which gave 100% correct classification of two species, E. rugosum and E. salvelini , and a high proportion of correct classification for E. crassum (98%) and E. fragile (83%). Of the latter two species, one specimen of E . crassum and five specimens of E. fragile were misclassified between the respective groups. The principal characters used in the classification of the species were the width of the egg, the length of the mediolateral hooks, and the width of the oncosphere. To provide more information on the life cycle of each species, the eggs were used in a series of infection trials to identify appropriate intermediate hosts. Experimental infections with freshwater copepods were successful when exposed to the eggs of E . salvelini , partially successful when exposed to the eggs of marine E. crassum with 10% of the copepods becoming infected, but no infections were obtained when the eggs of E. fragile were used.     

Requirement for omega and (omega;-1)-hydroxylations of fatty acids by human cytochromes P450 2E1 and 4A11.

Human liver microsomes and recombinant human P450 have been used as enzyme source in order to better understand the requirement for the optimal rate of omega and (omega;-1)-hydroxylations of fatty acids by cytochromes P450 2E1 and 4A. Three parameters were studied: alkyl chain length, presence and configuration of double bond(s) in the alkyl chain, and involvement of carboxylic function in the fatty acid binding inside the access channel of P450 active site. The total rate of metabolite formation decreased when increasing the alkyl chain length of saturated fatty acids (from C12 to C16), while no hydroxylated metabolite was detected when liver microsomes were incubated with stearic acid. However, unsaturated fatty acids, such as oleic, elaidic and linoleic acids, were omega and (omega;-1)-hydroxylated with an efficiency at least similar to palmitic acid. The (omega;-1)/omega ratio decreased from 2.8 to 1 with lauric, myristic and palmitic acids as substrates, while the reverse was observed for unsaturated C18 fatty acids which are mainly omega-hydroxylated, except for elaidic acid showing a metabolic profile quite similar to those of saturated fatty acids. The double bond configuration did not significantly modify the ability of hydroxylation of fatty acid, while the negatively charged carboxylic group allowed a configuration energetically favourable for omega and (omega;-1)-hydroxylation inside the access channel of active site.     

Dietary effects of omega 3-fatty acids on intestinal transport function

Animals were fed for 2 weeks on one of four isocaloric and isocholesterolic semisynthetic diets: high 18:3 omega 3, low 18:3 omega 3, high 20:5 omega 3, or low 20:5 omega 3. The weight of the intestine and the percentage of the wall consisting of mucosa was greater in high 20:5 omega 3 than in high 18:3 omega 3, and greater in low 20:5 omega 3 than in low 18:3 omega 3, although the mucosal surface area was 26% lower in high 20:5 omega 3 than high 18:3 omega 3. The jejunal uptake of 40 mM glucose and ileal uptake of 40 mM galactose was greater in high 18:3 omega 3 than in high 20:5 omega 3, jejunal uptake of fatty acid 12:0 was higher, but 18:0 was lower in high 18:3 omega 3 than in high 20:5 omega 3. The jejunal or ileal uptake of cholesterol was not affected by 20:5 omega 3. However, 20:5 omega 3 had a variable effect on the uptake of medium- and long-chain fatty acids. Alterations in the uptake of fatty acids and glucose were not explained by any difference in the animals' food consumption, body weight gain, or intestinal weight, but the reduced jejunal uptake of 40 mM glucose in rats fed the high 20:5 omega 3 diet was associated with reduced mucosal surface area. Thus, (i) varying the source of omega 3-fatty acids (vegetable, 18:3 omega 3 versus fish oil, 20:5 omega 3) altered the mucosal mass of the intestine, and (ii) the source of the dietary omega 3-fatty acid (18:3 omega 3 versus 20:5 omega 3) influenced intestinal hexose uptake, with fish oil having an anti-absorptive effect on the jejunal uptake of D-glucose.     

Regulation of fatty acid biosynthesis as a possible mechanism for the mitoinhibitory effect of fumonisin B1 in primary rat hepatocytes

The mitoinhibitory effect of fumonisin B1 (FB1) on the mitogenic response of epidermal growth factor (EGF) was investigated in primary hepatocyte cultures with respect to the alterations in the omega6 fatty acid metabolic pathway. Fatty acid analyses of hepatocytes showed that EGF treatment resulted in a significant decrease in the relative levels of 20:4omega6 (arachidonic acid) and an increase in 18:2omega6 (linoleic acid). Supplementation of the hepatocyte cultures with 20:4omega6 in the absence of EGF resulted in an increase in the total omega6 and omega6/omega3 fatty acid ratio. Addition of 20:5omega3 (eicosapentaenoic acid) resulted in an increase of the relative levels of the long chain omega3 fatty acids at the expense of the omega6 fatty acids. When 20:4omega6 and 20:5omega3 was added in the presence of EGF, the mitogenic response of EGF was increased and decreased respectively. When compared to the fatty acid profiles in the absence of EGF, the decreased mitogenic response coincided with a decrease of total omega6 fatty acids and total polyunsaturated fatty acids (PUFA). In addition, the saturated and mono-unsaturated fatty acids increased and the polyunsaturated/saturated (P/S) fatty acid ratio decreased which implied a more rigid membrane structure. Addition of prostaglandin E2 (PGE2) and prostaglandin E1 (PGE1) stimulated and inhibited the mitogenic response respectively. Ibuprofen, a known cyclooxygenase inhibitor, and FB1 inhibited the EGF-induced mitogenic response in a dose-dependent manner. The mitoinhibitory effect of FB1 on the EGF response was counteracted by the addition of PGE2. FB1 also disrupts the omega6 fatty acid metabolic pathway in primary hepatocytes, resulting in the accumulation of C18:2omega6 in phospatidylcholine and triacylglicerol. The disruption of the omega6 fatty acid metabolic pathway and/or prostaglandin synthesis is likely to be an important event in the mitoinhibitory effect of FB1 on growth factor responses.     

Human infections with Dicrocoelium dendriticum in Kyrgyzstan: the tip of the iceberg?

Dicrocoelium dendriticum is the causative agent of a rare food-borne zoonosis of the human biliary tract, dicrocoeliasis, for which few human prevalence data are available. Infection occurs through the ingestion of ants containing metacercariae, whereas pseudo-infections (presence of D. dendriticum eggs in stool in the absence of adult worms) are due to the consumption of infected animal liver. Here, results from a cross-sectional survey carried out among 138 children aged 2-15 yr in a peri-urban area of Kyrgyzstan are reported. Each child provided 1 stool sample that was subjected to the FLOTAC technique. Eggs of D. dendriticum were diagnosed in 11 children (prevalence 8.0%; 95% confidence interval 4.5-13.7%). Although no distinction could be made between true and pseudo-infections, the prevailing animal husbandry system and the diet and hygienic conditions of the study area suggest that the social-ecological system in Kyrgyzstan is conducive for human transmission of D. dendriticum. There is a need to investigate the epidemiology of dicrocoeliasis in Kyrgyzstan, placing emphasis on the distinction between true and pseudo-infections.     

Metabolic interactions among polyunsaturated fatty acids in response to an atherogenic diet.

The distribution of fatty acids in hepatic lipids of dogs fed a diet containing hydrogenated coconut oil as the only source of lipid, changed in the manner characteristic of essential fatty acid deficiency. Cholesterol supplementation of this diet accentuated these changes resulting in further increases in oleic and eicosatrienoic acids and decreases in the distribution of linoleic and arachidonic acids. Two eicosatrienoic acid isomers, 20:3 omega9, derived from oleic acid and 20:3 omega6, an intermediate in the biosynthesis of arachidonic acid from linoleic acid, were identified. The increase of the 20:3 omega6 isomer was found, somewhat unexpectedly, to be greater than that of 20:3 omega9, the isomer normally associated with EFA defiency. The increase in 20:3 omega6 was probably due in part, but not completely, to competitive inhibition by the increased concentration of 20:3 omega9 on the desaturation reaction whereby 20:3 omega6 is converted to arachidonic acid.     

Comparison of surface topography of three species of Diphyllobothrium (Cestoda,pseudophyllidea) by scanning electron microscopy

Plerocercoids of different sizes as well as adult worms of D. dendriticum, D. latum and D. ditremum were studied using scanning electron microscopy (S.E.M.). In the plerocercoids there were found distinct differences in appearance and length of microtriches between these three species, while the microtriches of adult worms were more similar. A regional difference in microtrix appearance was found in the larvae of D. ditremum and D. dendriticum. This was not apparent with S.E.M. in adult worms. The length of ‘body’ microtriches in D. dendriticum varied with the length of the larvae. The topography of the genital atrium of mature and gravid proglottids in adult worms of these three species is also described.     

Egg size and form as taxonomic criteria in Diphyllobothrium (Cestoda, Pseudophyllidea)

The size and form (length, width, and length: width ratio) of eggs of Diphyllobothrium dendriticum, D. ditremum and D. latum vary considerably among individual worms within each species. The size of eggs varies with host species and a decrease in egg size with increasing intensity of infestation is indicated. The egg size of D. latum increases during the first 10-12 days of egg production. For single worm infections in golden hamsters the mean egg length and width of D. ditremum are significantly smaller than the corresponding means of D. dendriticum and D. latum, while D. latum has significantly wider eggs than D. dendriticum. As taxonomic characteristics, egg size and form may contribute to species delimitation at the population level. For identification at the individual level the best possible accuracy is about 80%. This accuracy is considerably reduced when variation in host species and intensities of infestations are introduced. Scanning electron microscope studies did not reveal any differences among eggs of the three species.     

Host specificity and geographical distribution of Eubothrium in European salmonid fish

The host specificity and distribution of Eubothrium crassum (Bloch, 1779) and Eubothrium salvelini (Schrank, 1790), morphologically fairly similar pseudophyllidean tapeworms parasitizing salmonid fish, were critically assessed on the basis of morphological and genetic evaluation of extensive material collected from different definitive hosts and geographical regions in Europe. Eubothrium crassum occurs in fish of the genera Salmo, i.e. salmon (S. salar - both freshwater and marine), sea trout (S. trutta trutta), brown trout (S. trutta fario), and lake trout (S. trutta lacustris), and also in Danubian salmon (Hucho hucho) and vendace (Coregonus albula). Eubothrium salvelini parasitizes Arctic char (Salvelinus alpinus) and brook trout (Salvelinus fontinalis) in Europe, and also whitefish (Coregonus wartmanni). Rainbow trout (Oncorhynchus mykiss), which is not a native European fish species, was found to be a suitable definitive host for both Eubothrium species, which may occur simultaneously in the same fish. Previous records of E. crassum in Arctic char and brook trout, and those of E. salvelini in fish of the genus Salmo were most probably misidentifications. Most studies of Eubothrium have involved salmonids from the northern part of Europe, with few records from southern and south-eastern Europe. This study also confirmed the reliability of the morphology of the apical disc for the discrimination of E. crassum and E. salvelini.     

Temperature effects on embryonic development and the life cycle of Diphyllobothrium dendriticum

Diphyllobothrium dendriticum eggs collected from hamster faeces were incubated at 10 or 20 degrees C, or maintained at 4 degrees C for 11-30 months. On day 65, 20-50% of eggs failed to hatch at 10 degrees C and 42-51% did not hatch by day 21 at 20 degrees C. Our study indicates that eggs begin to hatch in mid-August and persist until October in many lakes within the natural range of D. dendriticum. Our results demonstrate that eggs stored at 4 degrees C will hatch, suggesting they can persist in the environment for long periods and contribute to the D. dendriticum life cycle in high Arctic lakes by hatching months or years after release.     

Studies on the biology of Eubothrium salvelini and E. crassum in resident and migratory Salvelinus alpinus and Salmo trutta and in S. salar in North Norway and the islands of Spitsbergen and Jan Mayen

Samples of Eubothrium salvelini and E. crassum were obtained from resident and migratory Salvelinus alpinus and Salmo trutta and from S. salar at sea from North Norway and the islands of Spitsbergen and Jan Mayen. Scolex dimensions proved an unsuitable character for identifying these two parasite species, and use of alternative characters confirmed that E. salvelini is specific to Salvelinus and E. crassum to Salmo. Distributions of both species are co-extensive with their hosts, but levels of infection in any locality relate to the abundance of zooplankton. E. salvelini exhibits seasonal maturation and incidence cycles in char. It is recognised as being a freshwater parasite, although some individuals can survive the period of marine migration of sea char. Returning migrant char may contain such individuals together with small plerocerciform parasites acquired almost immediately upon their re-entry to freshwater. No evidence for marine infections with E. salvelini was found. The presence of plerocerciform and gravid adult E. crassum in salmon caught at sea confirms the existence of a marine life cycle and a marine race in this species. In salmon moving from one medium to the other the marine and freshwater races replace each other, but in sea trout, which spend shorter periods at sea, complete replacement may not occur and at any one time fish may harbour individuals of both races. Recognition of the existence of two races clarifies much of the confusion surrounding the biology of this species.     

Relationship between essential fatty acid requirements of aquatic animals and the capacity for bioconversion of linolenic acid to highly unsaturated fatty acids.

1. [1-14C]linolenic acid was injected into the rainbow trout, Salmo gairdnerii, ayu, Plecoglossus altivelis, eel, Anguilla japonica, red sea bream, Chrysophrys major, rockfish, Sebastiscus marmoratus, globefish, Fugu rubripes rubripes and prawn, Penaeus japonicus (molting stage D"1-D2), and the bioconversion of linolenic acid (18:3 omega 3) to highly unsaturated fatty acids such as eicosapentaenoic (20:5 omega 3) and docosahexaenoic (22:6 omega 3) acids was investigated. 2. Linolenic acid was converted to 20:5 omega 3 and 22:6 omega 3 intensively in the rainbow trout, moderately in the ayu, eel and prawn, but slightly in the red sea bream, rockfish and globefish. 3. These results were discussed in relation to the essential fatty acid requirements of the aquatic animals.     

Glucose intolerance associated to insulin resistance and increased insulin secretion in rats depleted in long-chain omega3 fatty acids.

An intragastric D-glucose tolerance test was performed, after overnight starvation, in female rats depleted in long-chain polyunsaturated omega3 fatty acids (omega3D rats) and control rats of same age and gender. The plasma D-glucose and insulin concentrations, insulinogenic index, and HOMA for insulin resistance were all higher, after overnight starvation, in omega3D rats than in control animals. Over the 120-minute period following the intragastric administration of D-glucose, the area under the curve for the same four variables was also higher in omega3D rats than in control animals. In addition to visceral obesity, liver steatosis, hypertension, and cardiac hypertrophy, the omega3D rats thus display further features of the metabolic syndrome, namely glucose intolerance and insulin resistance, despite hyperinsulinemia.