Maternal dietary fish oil enriches docosahexaenoate levels in brain subcellular fractions of offspring

Prompted by the speculated essentiality of docosahexaenoic acid (DHA) for neural development, this study was undertaken to investigate the incorporation of (n-3) fatty acids in the maternal diet into various phospholipids of infant rat brain subcellular fractions: microsomes (Ms), synaptosomes (Sy), myelin (My), and mitochondria (Mt). Two groups of infant rats were nourished by dams fed diets containing 20% of either corn oil (CO) or menhaden oil (MO) from 2 until 12 days of age. DHA but not eicosapen taenoic acid (EPA) was distributed to all subcellular fractions of infant rats in the CO group. The levels of DHA were higher in Ms and Mt than Sy and My, and higher in phosphatidylethanolamine (PE) and phosphatidylserine (PS) than phosphadylcholine (PC) and phosphatidylinositol (PI). The MO feeding enriched DHA in PE of all subcellular fractions, PS of all subcellular fractions, except My, PC of Sy, My and Mt, and PI of My. EPA was enriched in phospholipids in all subcellular fractions, except mitochondrial PS of the MO group. In the MO group, the ratios of EPA/ DHA, ranging from 0.01 to 0.85, in all subcellular phospholipids were markedly lower than that found in the mother-s milk (i.e., 1.5), suggesting an ability to elongate and desaturate EPA to DHA and/or disproportional uptake of the fatty acids by the brain. In PE of all subcellular fractions, the increased levels of DHA and EPA, with a concomitant reduction of arachidonic and/or linoleic acid, yielded higher ratios of total (n?3)/(n?6) fatty acids in the MO than the CO group. The inclusion of preformed DHA and EPA in the maternal diet provides an effective means to enrich these fatty acids in developing brains. © 1993 Wiley-Liss, Inc.     

Transient aggregation resistance of human blood platelets in fresh plasma II physiological relevance: influence of fish oil

In order to evaluate the physiological relevance of the blood platelet “transient aggregation resistance” (TAR) test we studied the effect on this test of two different amounts of fish oil, corresponding to .75 g g (2.5 mmol) and 1.5 g (5 mmol) of eicosapentaenoic acid respectively, added in a cross-over design to the normal diet of 16 healthy male volunteers.It appeared that the “baseline aggregation resistance”(BAR), equivalent to the classic platelet aggregation ADP-threshold, was not influenced by Maxepa while, in contrast, a significant prolongation of TAR occurred. Apparently platelet aggregation analysed early after blood withdrawal, measures aspects of physiological relevance which, due to their short half life, are missed in the original method.     

Apolipoprotein (a) mediates the lipoprotein (a)-induced biphasic shift in human platelet cyclic AMP

Lipoproteins are known to influence platelet cyclic adenosine monophosphate (c-AMP) levels. Lipoprotein (a) (Lp(a))'s impact on platelet c-AMP levels has never been assessed. Increasing levels of purified human Lp(a) (1–100) mg/dl were incubated with washed human platelets. Lp(a) concentrations of 1–25 mg/dl resulted an initial statistically significant increase of platelet c-AMP above basal levels and decreased collagen-stimulated platelet aggregation levels. Higher concentrations progressively returned the platelet c-AMP concentrations to basal levels accompanied by further decreases in platelet aggregation. Increasing concentrations of purified apolipoprotein (a) (apo(a)) also resulted in a similar biphasic c-AMP response while Lp(a) without apo(a) was without impact. One antibody directed against apo(a) in intact Lp(a) removed the biphasic c-AMP pattern and eliminated Lp(a) platelet aggregation. Antibodies directed against apo B in intact Lp(a) gave results similar to intact Lp(a) in terms of the biphasic response of c-AMP upon platelet exposure to increasing levels of Lp(a). It is concluded that apo(a) mediates the Lp(a)-induced biphasic response in platelet c-AMP as the result of platelet exposure to increasing levels of Lp(a). The biphasic response in c-AMP assists in platelet aggregation decreases up to a concentration of 25 mg/dl Lp(a), such assistance being lost at higher Lp(a) concentrations.     

Lp(a) Lipoprotein in Cerebrovascular Disease and Dementia

Abstract: Lp(a) lipoprotein has been considered an independent risk factor in the development of coronary heart disease (CHD). We examined the role of Lp(a) in patients with cerebrovascular disease (CVD) and those with dementia.
The Lp(a) concentration in patients with CHD, those with cerebral infarction due to a large artery occlusion and those with vascular dementia (VD) was significantly higher than that of age-matched control subjects. However, the Lp(a) concentration was not high in cerebral infarction due to a small artery occlusion, intracerebral hemorrhage and dementia of the Alzheimer type (DAT).
The present results suggest that Lp(a) should cause VD as well as CVD, and that Lp(a) should be one of the indicators that distinguish VD from DAT.     

The effects of a mixed fish diet on platelet function, fatty acids and serum lipids

Eight healthy subjects were fed a diet containing 1–4 g eicosapentaenoic acid (EPA) daily for 8–21 days. The EPA was derived from 300–400 g per day of sardines, pilchards, herring and/or kabeljou. Sources of arachidonic acid (AA) in the diet were reduced. At the end of the experimental period there was an increase in the ratio of EPA to AA in the platelets and a decrease in platelet aggregation to ADP, epinephrine and collagen. Aggregation to AA was not reduced. Thromboxane production in response to all four agonists was reduced. Serum total and HDL cholesterol levels fell significantly but platelet counts, LDL cholesterol and triglyceride values did not change. We conclude that even a relatively modest intake of EPA derived from a mixed fish diet together with a reduction in AA intake can alter $\text{in vitro}$ platelet function and serum lipids significantly. A long term controlled trial of a palatable mixed fish diet to assess possible antithrombotic and antiatherogenic effects is justifiable.     

Plasma fibrinolytic activity after ingestion of omega-3 fatty acids in human subjects

Plasma fibrinolytic activity was measured in human volunteers after 30 day periods of ingestion of a fish oil product (Max Vita) containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and a wheat germ oil product containing alpha linolenic acid. Compliance was confirmed by significant increases in plasma levels of EPA and DHA and by significant falls in serum triglyceride levels. Platelet aggregation in platelet rich plasma and in whole blood was not altered significantly by fish oil or wheat germ oil. Neither fish oil or wheat germ oil caused any significant change in tissue plasminogen activator (tPA) or its inhibitor (PAI) measured enzymatically or in tPA antigen measured by an ELISA method. All these analytes (tPA, PAI, and tPA antigen) were measured before and after venous compression.

There was no evidence of enhanced fibrinolytic activity after ingestion of omega-3 fatty acids in fish oil or in wheat germ oil.     

The effects of a vegetarian diet on platelet function and fatty acids

Nine healthy subjects taking an average mixed “Western” diet were placed on a vegetarian diet poor in arachidonic acid for four weeks. All animal and marine foods except for cows milk and milk products were excluded. Platelet aggregation responses to arachidonic acid and epinephrine increased slightly whereas responses to ADP and collagen were unchanged. Platelet thromboxane production, platelet counts, serum LDL cholesterol and triglycerides did not change but total and HDL serum cholesterol levels fell significantly. There was a significant rise in platelet arachidonic acid content but other platelet fatty acids did not change significantly. A reduction in dietary arachidonic acid did not inhibit platelet aggregation or thromboxane production.     

Inhibition of the availability of platelet factor 3 by increased concentration of lecithin in platelets caused by gonadal steroids

Platelet factor 3 (PF-3) activity and the phosphatide composition of plasma and platelets were studied in a group of oophorectomized women on estrogen-gestagen treatment. Based on the results the following hypothesis is put forward. An increased concentration of lecithin in the platelets stabilizes the platelet membrane and inhibits the conformational changes of the membrane which is supposed to precede the “availability” of PF-3. Estrogen treatment induces a decrease of plasma lysolecithin resulting in a decreased formation of platelet lecithin. The increased PF-3 activity observed during the estrogen dominated phase may thus not be due to an increase of lipids promoting clotting but to a decrease of platelet lecithin which normally prevents the “release” of clot promoting activities.     

血清脂蛋白（a）与缺血性脑卒中关系的临床研究

目的探讨脂蛋白（a）（Lp（a））是否为缺血性卒中的危险因素,以及Lp（a）水平与缺血性脑卒中类型和预后的关系。方法将缺血性脑卒中患者按急性卒中治疗低分子肝素试验．TOAST）分型标准分为心源性脑栓塞（CE）、大动脉粥样硬化性卒中（LAA）、小动脉卒中（SAA）、其他原因引发的缺血性卒中（SOE）和原因不明的缺血性卒中（SUE）。以同期入院的非脑卒中患者（经头颅CT或磁共振排除）作为对照组。病例组和对照组均于入院次日清晨空腹抽取静脉血,测定Lp（a）及其他各项血脂指标,并于入院及病程两周时分别行NHISS评分评估神经功能缺损程度,分析Lp（a）与卒中类型及NIHSS评分之间的关系。结果缺血性脑卒中组Lp（a）浓度及异常率均高于对照组（P〈0．05）,Lp（a）进入大动脉粥样硬化卒中患病因素的回归方程Lp（a）水平与卒中患者的NIHSS评分无相关性（P〉0．05）。结论高浓度Lp（a）可能参与了缺血性脑卒中的发生,并且可能是大动脉粥样硬化性卒中发生的危险因素,但与神经功能缺失程度和早期功能修复无关。     

缺血性脑血管病患者颈动脉斑块与TXB2、OxLDL、Lp(a)、Hcy相关性分析

目的探讨缺血性脑血管病的颈动脉斑块与TXB2、OxLDL、Lp(a)、Hcy的相关性,以更好的对该病进行预防、治疗。方法35例急性缺血性卒中患者和20名正常对照组行颈动脉血管彩色多普勒超声检测颈动脉斑块,采用ELISA双抗体夹心法测定血浆TXB2、OxLDL、Lp(a),采用荧光偏振免疫分析法测定Hcy的含量,两组相比,并作相关性分析。结果斑块最大厚度、血浆TXB2、OxLDL、Lp(a)、Hcy的含量均高于正常对照组(P<0.01)。斑块最大厚度与TXB2、OxLDL、Lp(a)呈正相关。结论颈动脉斑块,血浆TXB2、OxLDL、Lp(a)、Hcy可能与缺血性脑血管病相关;TXB2、OxLDL、Lp(a)可能参与促进颈动脉粥样硬化斑块的形成。     

A novel radioimmunometric approach to the assay of components of human haemostasis: 1. Assay of plasma fibrinopeptide a levels

A new and simple approach to the sensitive assay of individual components in complex biological fluids is outlined. The principle involves a competition between soluble and polyvinyl-immobilised antigen (Ag) for a monospecific antibody (ab′) and the subsequent assessment of this competition using an ¹²⁵I-labelled second antibody (ab″). The application of the method is described for the assay of fibrinopeptide A (FPA) in human plasma and a basal level of 400–4500 pgs/ml is reported. The assay procedure requires 3–4 hours, including a Bentonite treatment of the plasma which removes fibrinogen and allows nearly 100% recovery of the FPA. The interaction of fibrinogen with the FPA antiserum allows fibrinogen-coated polyvinyl plates to be used to monitor residual ab′. These fibrinogen-coated plates can be prepared and stored for months at 4°C without any change in their ability to bind the FPA antiserum.     

The protective effect of fish n-3 fatty acids on cerebral ischemia in rat prefrontal cortex

This study presents neuroprotective effects of fish n-3 EFA on the prefrontal cortex after cerebral ischemia and reperfusion. Eighteen rats divided into three groups. Group A rats were used as control. Cerebral ischemia and reperfusion was produced in rats either on a standard diet (Group B) or a standard diet plus fish n-3 EFA for 14 days (Group C). The malondialdehyde (MDA) levels and activities of superoxide dismutase (SOD) and catalase (CAT) were measured and the number of apoptotic neurons was counted. The levels of MDA and activities of SOD increased in Group B rats as compared to Group A rats, and decreased in Group C rats as compared to Group B rats. The activities of CAT increased in Group C as compared to Group B rats. The number of apoptotic neurons in the prefrontal cortex was lower in Group C as compared to Group B rats.     

oxLDL,Lp（a）与脑血管疾病的关系

测定５１例脑血管病和２０例对照组的血浆ｏｘＬＤＬ和血清Ｌｐ（ａ）。结果脑血管病组明显高于对照组，脑血管病各分组（脑出血、脑栓塞、蛛网膜下腔出血）的ｏｘＬＤＬ亦高于对照组，脑出血、脑梗塞分组的Ｌｐ（ａ）高于对照组。ｏｘＬＤＬ及Ｌｐ（ａ）异常与患者的性别、年龄、病程及常规血脂检查异常率无相关。结论：ｏｘＬＰＬ、Ｌｐ（ａ）升高与脑血管病发病密切相关，是估价中风危险因素重要的、独立的脂蛋白参数之一。     

Influence of granulocyte elastase-like proteinase (ELP) on platelet functions

The influence of granulocyte elastase-like proteinase (ELP) on platelet functions was investigated. ELP inhibited the platelet aggregations induced by a wide variety of agonists. The inhibition was marked in the case of receptor-mediated agonists such as thrombin, ristocetin, etc. It was moderate with the pervading agonist, arachidonic acid, and mild with the bypassing agonist, Ca²⁺ ionophore A23187. ELP inhibited the release of thromboxane A2 from platelets in the case of the platelet aggregation induced by thrombin. On the other hand, ELP did not inhibit the release of thromboxane A2 from platelets in the platelet aggregation induced by arachidonic acid or Ca²⁺ ionophore A23187. ELP suppressed the release of serotonin from platelets induced by thrombin, while it did not markedly suppress the release of serotonin induced by Ca²⁺-ionophore A23187. Treatment of platelets with ELP resulted in a slight increase of intraplatelet cAMP levels. These results suggest that ELP acts on receptors and inhibits platelet functions. As a results, ELP markedly inhibits the platelet functions such as aggregation or release of serotonin or thromboxane A2 stimulated by receptor-mediated agonists. ELP slightly elevates the CAMP level in the platelets, resulting in the mild inhibition of the platelet functions stimulated by the pervading agonist, arachidonic acid, or the bypassing agonist, Ca²⁺-ionophore A23187.     

Influence of plasma protease activation on electroimmunoassay and nephelometry of plasma fibronectin in sepsis

In vitro experiments have shown that proteases such as trypsin, kallikrein and plasmin may split plasma fibronectin, yielding changes in apparent mass concentration, i.e.: a decrease when using immunonephelometry (IN), and an increase when using electroimmunoassay (EIA). In the present in vivo study, plasma from 49 patients with severe infections was assayed for fibronectin by IN and EIA, and for prekallikrein, plasminogen and antithrombin. In patients with normal prekallikrein (n=26) and plasminogen (n=23), the agreement between the two fibronectin assay methods was good (ratio EIA/IN = 0.99 ± 0.06); a similar good agreement was found in 45 healthy blood donors (ratio 0.97 ± 0.02). In contrast, the 20 patients with low prekallikrein showed fibronectin values that were significantly higher by EIA than by nephelometry (ratio 1.27 ± 0.10, p<0.01). Similarly, the 26 patients with low plasminogen had a significantly increased ratio (1.21 ± 0.09, p<0.05). No such difference was seen, however, between patients with low or normal antithrombin. Thus, kallikrein and plasmin activation in vivo appear to increase the fibronectin concentration measured by EIA, possibly due to the formation of small fragments with increased electrophoretic motility.     

Sex-related differences in platelet morphology in whole blood (WB) and platelet-rich plasma (PRP)

The proportion of smooth, disc-shaped platelets (D) in freshly drawn, glutaraldehyde fixed whole blood (WB) and citrated platelet-rich plasma prepared at 37°C is compared for male (N = 55) and female (N = 31) donors. Female donors have significantly more %D than male donors and the variability in %D measured on repeated occasions over a period of 3–69 months is less for female donors. WB and PRP gave similar results. The sex-related differences in %D were not related to hematocrit or to concomitant use of oral contraceptives. There were no significant sex-related differences in platelet mean volume or in platelet plasma membrane surface area as determined by the osmotic spherocyte method. However, the volume of D is smaller for male donors. It is concluded that the sex-related differences in platelet morphology do not represent intrinsic differences in platelet size or measurable total plasma membrane but represent a selective shape change activation of the larger D in the circulation of male donors. The significance of these observations for the sex-related differences in risk of cardiovascular disease and efficacy of anti-thrombotic therapy awaits appropriate prospective epidemiological studies.