The effect of haem biosynthesis inhibitors and inducers on intestinal iron absorption and liver haem biosynthetic enzyme activities

The relation between haem biosynthesis and intestinal iron absorption is not well understood, we therefore investigated the effect of compounds that alter haem metabolism on duodenal iron absorption. CD1 mice were treated with either an inhibitor (succinyl acetone (SA)) or stimulator (2-allyl-2-isopropylacetamide (AIA)) of haem biosynthesis. 5-Aminolaevulinic acid (ALA) dehydratase and urinary ALA and porphobilinogen (PBG) levels, were determined. Intestinal iron absorption was assayed with in vivo and in vitro techniques. Liver hepcidin (Hamp1) and duodenal iron transporter mRNA levels were measured using RT-PCR. AIA caused increased hepatic ALA synthase (1.6-fold) and ALA dehydratase (1.4-fold, both p<0.005) activities and increased urinary ALA and PBG excretion (2.1- and 1.4-fold, p<0.005, p<0.05, respectively). In vivo intestinal iron absorption was reduced to 49% of control (p<0.005). Mice treated with SA showed decreased urinary ALA and PBG levels (75 and 55% control, both p<0.005) and reductions in both ALA synthase and ALA dehydratase activities (77 and 56% control, p<0.05, p<0.005, respectively) in the liver. Liver and duodenal haem and cytochrome oxidase levels were not significantly decreased. Iron absorption was enhanced (1.26-fold, p<0.05) and hepatic Hamp1 mRNA was reduced (53% of control, p<0.05). In vitro duodenal iron uptake after mice were injected with SA also demonstrated an increase in Fe(III) reduction and uptake (1.27- and 1.41-fold, p<0.01 respectively). Simultaneous injections of SA and ALA blocked the enhancing effect on iron absorption seen with SA alone. We conclude that alterations in haem biosynthesis can influence iron absorption and in particular, the intermediate ALA seems to be an inhibitor of iron absorption.     

The Role of n-3 Polyunsaturated Fatty Acids in the Prevention and Treatment of Breast Cancer

Breast cancer (BC) is the most common cancer among women worldwide. Dietary fatty acids, especially n-3 polyunsaturated fatty acids (PUFA), are believed to play a role in reducing BC risk. Evidence has shown that fish consumption or intake of long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are beneficial for inhibiting mammary carcinogenesis. The evidence regarding α-linolenic acid (ALA), however, remains equivocal. It is essential to clarify the relation between ALA and cancer since ALA is the principal source of n-3 PUFA in the Western diet and the conversion of ALA to EPA and DHA is not efficient in humans. In addition, the specific anticancer roles of individual n-3 PUFA, alone, have not yet been identified. Therefore, the present review evaluates ALA, EPA and DHA consumed individually as well as in n-3 PUFA mixtures. Also, their role in the prevention of BC and potential anticancer mechanisms of action are examined. Overall, this review suggests that each n-3 PUFA has promising anticancer effects and warrants further research.     

Different intakes of n-3 fatty acids among pregnant women in 3 regions of China with contrasting dietary patterns are reflected in maternal but not in umbilical erythrocyte phosphatidylcholine fatty acid composition

There is limited information regarding the intake and status of polyunsaturated fatty acids (PUFA) in Chinese pregnant women with different dietary patterns. We hypothesize that there will be significant differences in long chain n-3 and n-6 PUFA status in pregnant women from 3 regions of China (river/lake, coastal and inland). Dietary fatty acid intakes and fatty acid profiles in maternal and umbilical erythrocyte phosphatidylcholine (PC) were analyzed. The median daily intakes (mg) of eicosapentanoic acid and docosahexaenoic acid (DHA) in the coastal group (64.6 and 93.9, n = 42) were significantly higher than those in the river/lake group (27.9 and 41.8, n = 41) and the inland group (12.1 and 41.1, n = 40). Daily intake of arachidonic acid (AA) was highest (170.2 mg) in the inland group. The median DHA level (%) of maternal erythrocyte PC was comparable between river/lake and inland groups (5.7 vs. 5.6) while both were significantly lower than in coastal group (8.4). The median AA level (%) of maternal erythrocyte PC tended to be lower in the coastal group than in the inland group but the difference was not significant. The AA and DHA levels in umbilical erythrocyte PC were comparable among the 3 groups. In conclusion, differences in long chain n-3 PUFA intake between geographic regions, in particular in DHA, were reflected in differences in maternal erythrocyte PC DHA status but did not result in differences in umbilical erythrocyte PC.     

ALA光动力治疗鲍温样丘疹病临床研究

目的观察5氨基酮戊酸(5aminolevulinicacid,ALA)光动力疗法(photodynamictherapy,PDT)治疗鲍温样丘疹病的临床疗效。方法治疗组38例采用ALAPDT治疗,每周治疗1次,共治疗4次;对照组15例予以二氧化碳激光治疗。结果治疗组痊愈12例,显效12例,有效率为61.2%,复发2例,复发率16.7%,无明显疼痛、创面等副作用;对照组痊愈9例,显效3例,有效率为80.0%,复发5例,复发率55.5%,15例均有术后明显创面疼痛,8例合并创面感染,9例出现表浅瘢痕。两组之间有效率和复发率无显著性差异(P>0.05)。结论ALAPDT是治疗鲍温样丘疹病的一种安全、有效、无明显痛苦和不良反应的新疗法。     

Total dietary fat and fatty acid content modifies plasma phospholipid fatty acids,desaturase activity indices,and urinary prostaglandin E in women

Compared with diets high in fat, low-fat diets are associated with reduced risk of cardiovascular disease. We hypothesized that a low-fat (LF) (20% fat) and an LF high–omega-3 (n-3) fatty acid diet (LFn3) (23% fat with 3% as α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid [DHA]) would enhance n-3 composition of plasma phospholipid fatty acid and reduce urinary prostaglandin E₂ (PGE₂) relative to a high-fat diet (HF) (40% fat) and that these changes would be associated with alterations in δ5 desaturase (D5D) and δ6 desaturase (D6D) activity. Phospholipid fatty acids and urinary PGE₂ were measured, and D5D and D6D activity indices calculated in a crossover trial in 17 postmenopausal women fed each of 3 test diets (HF, LF, and LFn3) for 8-week feeding periods. Desaturase activity indices were calculated as D5D, 20:4n-6/20:3n-6, and D6D, 20:3n-6/18:2n-6. Plasma phospholipid fatty acid, α-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid (DPA), DHA, and total n-3 fatty acids increased, whereas linoleic acid and arachidonic acid decreased with consumption of LFn3. The LF resulted in enhanced arachidonic acid and DHA. High fat reduced D6D, whereas both HF and LF increased D5D. Urinary PGE₂ was reduced in response to both the LF and LFn3 diets. Low-fat diets, with or without long-chain n-3 fatty acids, promote positive health effects due in part to favorable alteration of plasma phospholipid fatty acid profiles and modification in desaturase activity indices, suggesting that the type and amount of fat consumed are modifiable risk factors for the prevention of cardiovascular disease.     

Fish oil supplementation maintains adequate plasma arachidonate in cats,but similar amounts of vegetable oils lead to dietary arachidonate deficiency from nutrient dilution

Because fatty acid (FA) metabolism of cats is unique, effects of dietary fish and vegetable oil supplementation on plasma lipids, lipoproteins, lecithin/cholesterol acyl transferase activities, and plasma phospholipid and esterified cholesterol (EC) FAs were investigated. Cats were fed a commercial diet supplemented with 8 g oil/100 g diet for 4 weeks using either high-oleic-acid sunflower oil (diet H), Menhaden fish oil (diet M), or safflower oil (diet S). When supplemented, diet M contained sufficient arachidonate (AA), but diets H and S were deficient. We hypothesized that diet M would modify plasma lipid metabolism, increase FA long-chain n-3 (LCn-3) FA content but not deplete AA levels. Also, diet S would show linoleic acid (LA) accumulation without conversion to AA, and both vegetable oil supplements would dilute dietary AA content when fed to meet cats' energy needs. Plasma samples on weeks 0, 2, and 4 showed no alterations in total cholesterol or nonesterified FA concentrations. Unesterified cholesterol decreased and EC increased in all groups, whereas lecithin/cholesterol acyl transferase activities were unchanged. Diet M showed significant triacylglycerol lowering and decreased pre–β-lipoprotein cholesterol. Plasma phospholipid FA profiles revealed significant enrichment of 18:1n-9 with diet H, LA and 20:2n-6 with diet S, and FA LCn-3FA with diet M. Depletion of AA was observed with diets H and S but not with diet M. Diet M EC FA profiles revealed specificities for LA and 20:5n-3 but not 22:5n-3 or 22:6n-3. Oversupplementation of some commercial diets with vegetable oils causes AA depletion in young cats due to dietary dilution. Findings are consistent with the current recommendations for at least 0.2 g AA/kg diet and that fish oil supplements provide both preformed LCn-3 polyunsaturated FA and AA.