大豆磷脂对红细胞膜脂类成分的影响

目的:研究大豆磷脂对小鼠红细胞膜脂肪酸和磷脂成分的影响。方法:小鼠用不同剂量的大豆磷脂灌胃,分别为2.5、5.0、10.0 g/kg bw,同时设立对照组(去离子水灌胃),连续灌胃30 d后,心脏取血,高效液相色谱法测定小鼠红细胞膜中脂肪酸和磷脂的成分及含量。结果:(1) 10.0 g/kg剂量组小鼠红细胞膜中C18∶2、C18∶3含量等多不饱和脂肪酸(PUFA)含量显著增加(P<0.05),而C18∶1的含量则显著下降(P<0.05);5.0 g/kg剂量组C18∶2含量显著提高(P<0.05)。(2) 10.0 g/kg剂量组小鼠红细胞膜中磷脂酰丝氨酸(PS)、红细胞膜神经磷脂 (SM)、磷脂酰乙醇胺 (PE)、磷脂酰胆碱(PC)的含量均显著增加(P<0.05),而SM/PC的比值显著下降(P<0.05);5.0 g/kg剂量组PE、PC的含量显著增加(P<0.05)。结论:大豆磷脂能增加红细胞膜多不饱和脂肪酸和磷脂含量,改善红细胞膜脂类成分。     

高效液相色谱法测定鸡蛋中PC和PE含量研究

[目的]建立高效液相色谱-紫外检测器测定蛋黄中磷脂酰胆碱(PC)和磷脂酰乙醇胺(PE)含量的方法。[方法]采用Zorbax XDB C18(150 mm×4.6 mm×5μm)色谱柱,以乙腈∶甲醇∶异丙醇=10∶80∶10(v/v)为流动相,流速1.0ml/min,柱温35℃,UV 208 nm的色谱系统。[结果]蛋黄中PC的平均回收率为86.4%;PE的平均回收率为88.0%,PC的RSD为3.4%(n=6);PE的RSD为2.8%(n=6),PC的线性范围0.050~0.40 mg/ml(r=0.9990);PE的线性范围0.050~0.40 mg/ml(r=0.9991)。[结论]建立的方法用于蛋黄中PC、PE含量的测定,操作简便、快速。     

肠外营养中脂肪乳剂对红细胞膜磷脂脂肪酸组成的影响

利用大鼠胃肠外营养(PN)模型观察长链脂肪乳剂(LCT),中链/长链脂肪乳剂(MCT/LCT),以及不含脂肪乳剂对红细胞(RBC)膜磷脂肪酸组成的影响。PN总热量为300kcal.kg~(-1).d~(-1),非蛋白热卡:氮为182:1,LCT组,MCT/LCT组分别由10％的Intralipid和10％的Lypofundin提供30％的非蛋白热卡。7天后,分析RBC膜磷脂酰二极管胆硷(PC)脂肪酸组成。结果发现,不含脂肪乳剂组18:1n-9明显高于对照组;LCT组18:2n-6升高,而20:4n-6却下降;MCT/LCT组与对照组相比,脂肪酸组成变化不明显。结论:无脂肪乳剂TPN导致必需脂肪酸缺乏;LCT组由于18:2n-6的过量供给,抑制Δ6去饱和酶的活性,MCT/LCT组由于50％LCT被MCT替代,减低了对此酶活性抑制。     

早产婴儿应用10%和20%脂肪乳剂的全肠外营养时脂清除率的比较

早产婴儿全肠外营养时,脂肪乳剂是重要的能量来源。但由于其血浆脂清除率下降,脂肪的量受到限制。作者随机对48例早产婴儿在产后第一天应用四种不同的脂肪乳剂(附表)其甘油三酯/磷脂(0.12或0.06》,乳化剂组成(磷脂乙醇胺/磷脂胆硷,(PE/PC)     

孕妇葡萄糖耐量试验中血浆脂肪酸与血糖、胰岛素水平关系的研究

目的:研究血浆脂肪酸组成与孕妇糖耐量和餐后胰岛素水平的关系。方法:对76名怀孕24～28w的孕妇进行50g葡萄糖耐量试验,并收集血样测定血浆胰岛素、脂肪酸、甘油三酯和总胆固醇。血浆脂肪酸测定采用气相色谱法。结果:餐后血糖和胰岛素水平分别与血浆单不饱和脂肪酸、C14∶0、C16∶0、C16∶1n-7和C18∶1n-9的相关系数为正值(P<0.05),而与血浆多不饱和脂肪酸、C18∶2n-6、C20∶4n-6的相关系数为负值(P<0.05);另外餐后血糖水平与饱和脂肪酸的相关系数为正值(P<0.05),与C22∶6n-3的相关系数为负值(P<0.05)。进一步的多因素分析发现,控制年龄和孕前BMI后,血浆多不饱和脂肪酸含量分别与餐后血糖和胰岛素水平呈负相关;就单个脂肪酸而言,亚油酸(C18∶2n-6)和花生四烯酸(C20∶4n-6)与血糖水平呈负相关,亚油酸(C18∶2n-6)还与餐后胰岛素呈负相关。结论:本次研究以血浆脂肪酸组成作为膳食脂肪摄入水平的生物学指标,发现血浆中多不饱和脂肪酸比例较高,尤其是亚油酸和花生四烯酸比例较高对孕妇糖代谢起到有利作用。     

二十碳五烯酸改变JurkatT细胞膜脂肪微区域脂肪环境的研究

目的:研究二十碳五烯酸(EPA)处理后T细胞膜脂肪微区域中脂肪酸组成改变及其对磷脂分子中脂肪酰基取代基团的作用。方法:用不连续蔗糖密度梯度超速离心法分离T细胞膜脂肪微区域,然后用气相色谱分析细胞膜亚区域中脂肪酸组成,高效液相质谱联用测定膜脂肪微区域磷脂分子脂肪酸酰基取代基团的构成。结果:EPA处理使T细胞脂肪微区域中多不饱和脂肪酸(PUFAs),n-3PUFAs和n-3PUFAs/n-6PUFAs的比值升高;磷脂分子中除了鞘磷脂以外,其他的磷脂分子如磷脂酰胆碱、磷脂酰乙醇胺、磷脂酰丝氨酸、磷脂酰肌醇分子中一些脂肪酰取代基团有显著改变。结论:EPA处理明显改变T细胞膜脂肪微区域和可溶膜组分中脂肪酸的组成,改变磷脂分子脂肪酰基取代基团的构成,从而改变细胞膜脂肪微区域的脂肪环境。     

学龄前肥胖儿童硬脂酰辅酶A去饱和酶的变化

目的:观察学龄前肥胖儿童血浆单不饱和脂肪酸(monounsaturated fatty acids,MUFAs)水平及硬脂酰辅酶A去饱和酶(stearoyl-CoA desaturase,SCD)活性的变化,探讨其与体重指数(body mass index,BMI)之间的关系。方法:选取36例3~6岁的单纯性肥胖儿童并按性别、年龄1∶1配对的36例正常儿童。利用气相色谱分析方法测定其血浆脂肪酸组成,以棕榈油酸/棕榈酸(C16∶1n-7/C16∶0)比值代表SCD活性。结果:肥胖儿童血浆棕榈油酸、油酸(C18∶1n-9)、MUFA总量及SCD活性较正常儿童均显著升高(P<0.05);相关性分析显示,肥胖儿童SCD活性与BMI呈显著正相关关系(P<0.05)。结论:SCD活性及MUFAs水平升高在肥胖发生中可能起着一定的作用,但具体情况尚有待进一步探讨。     

母亲外周血单个核细胞HBV感染对围生儿的影响

目的探讨母亲HBV感染的外周血单个核细胞在HBV宫内感染中的作用。方法用套式多聚酶链反应(nPCR)法分别检测41例HBsAg阳性、12例HBsAg阴性而其他标志物阳性和16例乙肝血清标志物全部阴性的孕产妇及其新生儿血清和外周血单个核细胞中的HBVDNA。结果HBsAg阳性产妇外周血单个核细胞中的HBVDNA阳性率为31.7%(13/41);外周血单个核细胞感染率与血清HBeAg和HBVDNA的状态及水平无关(P>0.05);新生儿外周血单个核细胞HBVDNA阳性率在母亲血清和外周血单个核细胞HBVDNA均阳性组显著高于仅血清阳性组;母亲外周血单个核细胞HBVDNA阳性组显著高于阴性组(P<0.05);1例母亲血清HBVDNA阴性而外周血单个核细胞HBVDNA阳性,其新生儿血清中检出HBVDNA。结论母亲HBV感染的外周血单个核细胞有可能作为载体导致HBV宫内感染。     

接苯工人胸腺近期输出功能和外周血T细胞亚群变化

目的分析接苯工人外周血单个核细胞中T细胞受体删除DNA环(TRECs)和T淋巴细胞亚群的含量,了解接苯后工人胸腺近期输出功能和外周T淋巴细胞亚群变化,为接苯后机体细胞免疫改变提供资料。方法利用间接免疫荧光法检测健康人和接苯工人外周血单个核细胞中CD3 ,CD4 ,CD8 的含量;采用实时荧光定量聚合酶链反应(real time PCR)和TaqMan方法检测标本外周血单个核细胞中TRECs的含量。结果在接苯工人外周血白细胞总数正常情况下,接苯组CD8 含量显著增加,CD4 /CD8 比值为(1.13±0.78),低于健康人(1.43±0.25)(P<0.05)。每1000个外周血单个核细胞中接苯组与对照组TRECs含量分别为(3.90±3.58)和(7.39±6.83),两者相比,差异有统计学意义(P<0.05)。结论长期低剂量接苯可能引起一些工人的胸腺近期输出功能低下,导致机体细胞免疫功能障碍。     

齐齐哈尔市售乳制品中反式脂肪酸的测定

目的了解市售乳制品中是否存在反式脂肪酸,并测定其存在的种类和含量。方法随机抽取市售的奶粉、纯牛奶和酸奶3种奶制品,采用气相色谱法外标法定量,分别对3种乳制品中反式脂肪酸组成进行测定。结果硬脂酸甲酯(C18∶0)、顺式油酸甲酯(C18∶1-9c)与反式油酸甲酯(C18∶1-9t),顺式亚油酸甲酯(C18∶2-9c,12c)与反式亚油酸甲酯(C18∶2-9t,12t)分离效果良好。3种乳制品中反式脂肪酸均有检出,反式脂肪酸含量为0.129~0.216 g/100 g。结论市售的奶粉和纯牛奶样品检出1种反式脂肪酸,酸奶样品检出2种反式脂肪酸。     

Effect of dietary fatty acid composition on inositol-, choline- and ethanolamine-phospholipids of mammary tissue and erythrocytes in the rat.

The present study investigated the effect of feeding maize-oil, olive-oil and fish-oil diets, from weaning to adulthood, on rat mammary tissue and erythrocyte phospholipid fatty acid compositions. Effects of diet on the relative proportions of membrane phospholipids in the two tissues were also investigated. Mammary tissue phosphatidylinositol (PI) fatty acids were unaltered by diet, but differences in phosphatidylethanolamine (PE) and, to a lesser extent, phosphatidylcholine (PC) fractions were found between animals fed on different diets from weaning. Differences observed were those expected from the dietary fatty acids fed; n-6 fatty acids were found in greatest amounts in maize-oil-fed rats, n-9 in olive-oil-fed rats, and n-3 in fish-oil-fed rats. In erythrocytes the relative susceptibilities of the individual phospholipids to dietary modification were: PE > PC > PI, but enrichment with n-9 and n-3 fatty acids was not observed in olive-oil- and fish-oil-fed animals and in PC and PE significantly greater amounts of saturated fatty acids were found when animals fed on olive oil or fish oil were compared with maize-oil-fed animals. The polyunsaturated:saturated fatty acid ratios of PE and PC fractions were significantly lower in olive-oil- and fish-oil-fed animals. No differences in the relative proportions of phospholipid classes were found between the three dietary groups. It is suggested that differences in erythrocyte fatty acid composition may reflect dietary-induced changes in membrane cholesterol content and may form part of a homoeostatic response the aim of which is to maintain normal erythrocyte membrane fluidity. The resistance of mammary tissue PI fatty acids to dietary modification suggests that alteration of PI fatty acids is unlikely to underlie effects of dietary fat on mammary tumour incidence rates.     

Dietary n-3 and n-6 fatty acids alter avian metabolism: molecular-species composition of breast-muscle phospholipids

The effects of diets high in n-3 polyunsaturated fatty acids (PUFA; provided by fish oil), n-6 PUFA (sunflower oil) or in more-saturated fatty acids (tallow) on the distribution of subclasses of choline phospholipids (PC) and ethanolamine phospholipids (PE) from the breast muscle of broiler chickens were examined. Supplementation with the different fatty acids had no effect on the distribution of phospholipid subclasses. Feeding sunflower oil or tallow gave a molecular-species profile similar in both fatty acid subtype and proportion. In the diacyl PC phospholipids, 16 : 0-18 : 1n-9 and 16 : 0-18 : 2n-6 accounted for approximately 60 % of the total molecular species, whereas for the alkylenyl PC the predominant species were 16 : 0-18 : 1n-9 and 16 : 0-20 : 4n-6. Of the diacyl PE the dominant species was 18 : 0-20 : 4n-6 which accounted for 50 % of the molecular species, and of the alkylenyl PE the dominant species were 16 : 0-18 : 1n-9, 16 : 0-20 : 4n-6 and 18 : 0-20 : 4n-6. Supplementation with fish oil significantly increased levels of both eicosapentaenoic acid (20 : 5n-3) and docosahexaenoic acid (22 : 6n-3) in PC and PE when compared with either sunflower oil or tallow supplementation. The increase in the n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (20 : 4n-6) in both PC and PE. Different dietary fats induce different patterns of fatty acid incorporation and substitution in the sn-2 position of the diacyl and alkylenyl PC and PE of avian breast muscle, and this finding is indicative of selective acyl remodelling in these two phospholipids.     

大豆磷脂对小鼠学习记忆及脑组织脂类成分的影响

目的　大豆磷脂对小鼠学习记忆、脑组织蛋白质和脂类成分的影响。方法　小鼠用不同剂量的大豆磷脂灌胃 ,分别为低剂量组 (2 5g kg)、中剂量组 (5 0g kg)、高剂量组 (10 0g kg) ,同时设立对照组 (去离子水 ) ,连续灌胃 30天 ,进行小鼠学习记忆测定后处死 ,取全脑 ,测定小鼠脑组织中蛋白质含量、磷脂和脂肪酸的成分及含量。结果　 (1)与对照组比较 ,高、中剂量组小鼠学习记忆能力显著增强 (P <0 0 5 ) ;低剂量组小鼠记忆力显著改善 (P <0 0 5 )。 (2 )各剂量组脑重占体重的比例及脑组织中蛋白质含量均显著上升 (P <0 0 5 )。 (3)高剂量组C1 8:2 含量、C1 8:3含量、PUFA占总脂肪酸的比例显著提高 (P <0 0 5 ) ;中剂量组C1 8:3含量有显著差异 (P <0 0 5 )。 (4 )高剂量组PS、PE、PC、PL含量显著增加 (P <0 0 5 ) ,SM PC的比值则显著下降 (P <0 0 5 ) ;中剂量组PS、PC、PL含量显著增加 (P <0 0 5 )。结论　提示大豆磷脂可明显提高小鼠脑组织中蛋白质、PUFA和PL的含量 ,显著改善小鼠学习记忆能力 ,且与大豆磷脂存在剂量对应关系。     

Effects of n-3 polyunsaturated fatty acids on coronary heart disease

The purpose of this paper is to discuss the role of n-6 and n-3 polyunsaturated fatty acids in coronary heart disease (CHD). The level of n-6 and n-3 fatty acids in plasma and cardiac phospholipids was examined in relation to CHD in man. The fatty acid profile of cardiac phospholipids was also examined in relation to various risk factors of CHD, such as the composition of dietary fat, aging and stress. Life expectancy in Iceland is higher than in other Nordic countries, and the cardiovascular diseases mortality is lower in Iceland in the older age groups. There is a positive correlation between the level of arachidonic acid (AA) in plasma phospholipids (PL) in the normal population and cardiovascular disease mortality in Nordic countries. The level of AA in plasma PL is significantly higher in patients with CHD than in normal subjects. Dietary intake of fish or fish oil lowers cellular levels of AA and favorably influences eicosanoid metabolism in platelets and leukocytes. The roles of n-6 and n-3 fatty acids in heart muscle are less well understood. Rats fed diets containing either 10% butter, corn oil or cod liver oil showed markedly different fatty acid composition of individual phospholipids in sarcolemma. Dietary cod liver oil lowered the AA level in sarcolemmal phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) by 50% compared to butter or corn oil fed rats, replacing AA with docosahexaenoic acid (DHA). Adaptation to moderate to severe stress induced by repeated administration of catecholamines for 15 days resulted in marked but reversible alterations in the fatty acid profile of cardiac phospholipids. During severe stress the level of AA increased by 50% in PC replacing linoleic acid (LA), whereas in PE the DHA increased markedly replacing LA. Aging was accompanied by similar alterations in cardiac phospholipids, increased levels of AA in PC and increased DHA in PE. The incidence of ventricular fibrillation (VF) and sudden cardiac death induced by isoproterenol in adult rats fed different dietary fat was lowest in rats fed cod liver oil, with a low ratio of AA/DHA in cardiac phospholipids. Mortality due to VF was highest in rats fed corn oil with the highest ratio of AA/DHA. Sudden cardiac death in man was frequently associated with a higher ratio of AA/DHA than observed in people of the same age who died in accidents. The balance between n-6 and n-3 fatty acids in cellular phospholipids seems to play an important role in stress tolerance and survival.     

结构脂肪乳剂与物理混合的中/长链脂肪乳剂脂肪酸代谢比较研究

目的:比较结构脂肪乳剂(STG)与物理混合的中/长链脂肪乳剂(MCT/LCT)在人体内的脂肪酸代谢情况.方法:40例健康志愿者随机分为STG组和MCT/LCT组,每组20例.分别于早晨6h内匀速输注20%力文脂肪乳剂和20%力保肪宁脂肪乳剂1.0 g/(kg·次).并于给药前和给药后2、4、6和24 h留取血标本测定血...     

Dietary eritadenine and ethanolamine depress fatty acid desaturase activities by increasing liver microsomal phosphatidylethanolamine in rats

The effects of eritadenine, a constituent of the Lentinus edodes mushroom, and ethanolamine, the base constituent of phosphatidylethanolamine (PE), on fatty acid desaturase activities and lipid profiles were investigated comparatively in rats. Rats were fed a control diet or a diet supplemented with either eritadenine (0.05 g/kg) or ethanolamine (8 g/kg) for 14 d. Eritadenine and ethanolamine had marked hypocholesterolemic effects. The concentration of liver microsomal PE was significantly increased and the ratio of phosphatidylcholine (PC) to PE was significantly decreased by both eritadenine and ethanolamine. These changes in phospholipid profile were also observed in the mitochondria and plasma membranes in the liver. The activities of the Delta5-, Delta6- and Delta9-desaturases in liver microsomes were significantly decreased by eritadenine and ethanolamine; there was a significant correlation between the activity of Delta5- or Delta6-desaturase and the proportion of PE in the total phospholipids or the PC/PE ratio. Reflecting decreased Delta5- and Delta6-desaturase activities, the 20:4(n-6)/18:2(n-6) ratio was significantly decreased by eritadenine and ethanolamine in PC of the liver microsomes, mitochondria and plasma membranes. Although the 20:4(n-6)/18:2(n-6) ratio of liver microsomal PE was also significantly decreased by eritadenine and ethanolamine, the fatty acid composition of phosphatidylinositol and phosphatidylserine was less affected by these compounds. Eritadenine and ethanolamine increased the proportion of 16:0-18:2 and decreased the proportion of 18:0-20:4 in liver PC. The results suggest that dietary eritadenine and ethanolamine might lead to decreases in desaturase activities and changes in fatty acid and molecular species composition of PC through an increase in liver microsomal PE.     

Effects of dietary trilinoelaidate on liver mitochondrial phospholipids and endogenous phospholipase activity

Calcium activated phospholipase activity in intact liver mitochondria from chow fed rats released 30 nmoles fatty acids/mg protein/hr at pH 9.6. While more fatty acids were released from phosphatidylethanolamine (PE) versus phosphatidylcholine (PC), the pattern of release indicated that both phospholipase A₂ and A₁ were active in these mitochondrial preparations. The effects of dietary trilinoelaidate on liver mitochondrial phospholipase activity was studied. Dietary trilinoelaidate when fed to rats in amounts ranging from 0 to 6.3 energy percent in the presence of 1.0 energy percent trilinoleate was readily incorporated into all phospholipid (PL) classes of liver mitochondria. There was a decrease in the amounts of mitochondrial phosphatidylcholine (PC) and an increase in phosphatidylethanolamine IPE) with increasing levels of trilinoelaidate. The linoleic acid content (cc 18:2n6) of all PL classes markedly increased whereas the amounts of 20:3n9, 20:4n6 and 16:0 decreased with increased consumption of trilinoelaidate. Arachidonic acid (20:4n6) content of PC was depressed but it was unaltered in PE. Linoelaidate accumulated in both PE and PC cut not in cardiolipins. Dietary trilinoelaidate did not alter mitochondrial phospholipase activity. However, the pattern of fatty acids released by phospholipase from the mitochondrial phospholipids of the trilinoelaidate fed animals were different. These differences were attributed to the changes in membrane fatty acid composition rather than to altered phospholipase activity or specificity.     

Fatty acid composition of skeletal muscle reflects dietary fat composition in humans

BACKGROUND: It is still unknown whether the fatty acid composition of human skeletal muscle lipids is directly influenced by the fat composition of the diet. OBJECTIVE: We investigated whether the fatty acid composition of the diet is reflected in the fatty acid profile of skeletal muscle phospholipids and triacylglycerols. DESIGN: Thirty-two healthy adults (25 men and 7 women) included in a larger controlled, multicenter dietary study were randomly assigned to diets containing a high proportion of either saturated fatty acids (SFAs) [total fat, 36% of energy; SFAs, 18% of energy; monounsaturated fatty acids (MUFAs), 10% of energy] or MUFAs (total fat, 35% of energy; SFAs, 9% of energy; MUFAs, 19% of energy) for 3 mo. Within each diet group, there was a second random assignment to supplementation with fish oil capsules [containing 3.6 g n-3 fatty acids/d; 2.4 g eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)] or placebo. A muscle biopsy sample was taken from the vastus lateralis muscle after the diet period. Parallel analyses of diet and supplementation effects were performed. RESULTS: The proportions of myristic (14:0), pentadecanoic (15:0), heptadecanoic (17:0), and palmitoleic (16:1n-7) acids in the skeletal muscle phospholipids were higher and the proportion of oleic acid (18:1n-9) was lower in the SFA group than in the MUFA group. The proportion of total n-3 fatty acids in the muscle phospholipids was approximately 2.5 times higher, with a 5 times higher proportion of eicosapentaenoic acid (20:5n-3), in subjects supplemented with n-3 fatty acids than in those given placebo. Similar differences were observed in the skeletal muscle triacylglycerols. CONCLUSION: The fatty acid composition of skeletal muscle lipids reflects the fatty acid composition of the diet in healthy men and women.     

Effects of essential fatty acid contents of lipid emulsions on erythrocyte polyunsaturated fatty acid composition in patients on long-term parenteral nutrition

The effect of the long-term intravenous infusion of 2 lipid emulsions, differing in essential fatty acid (EFA) content, on fatty acid pattern of red blood cell (RBC) was investigated in 5 patients with inflammatory bowel disease. They were randomly assigned to receive daily intravenous infusion of either a soybean emulsion or a mixed medium-chain triacyl-glycerols (MCT): soybean emulsion, followed by the other, each for a period of 3 months. The soybean emulsion contained exclusively long-chain triacylglycerols (LCT) with 54% of C18:2n-6 and 6% of C18:3n-3. The mixed emulsion consisted of a 50:50 (w:w) mixture of soybean LCT and MCT, providing half the amount of the same EFA compared to LCT emulsion. The same phospholipid emulsifier was used in both preparations. Infusion of LCT for a 3 month period modified RBC fatty acid pattern as follows: 18:2n-6 increased, 20:4n-6 decreased as well as n-6:n-3 ratio. By contrast, infusion of MCT/LCT did not alter RBC fatty acids, and even tended to correct a pattern altered by the previous LCT infusion. The study demonstrates that soybean LCT provides an excess of C18: 2n-6 which affects the balance between RBC fatty acids in adult patients. Decreasing the intake of C18:2n-6 and C18: 3n-3, by using a mixed MCT/LCT emulsion, appears more appropriate for keeping a balanced pattern.