The effect of dietary fish oil containing eicosapentaenoic acid and docosahexaenoic acid on blood viscosity was compared with that of corn oil. Male Sprague-Dawley rats at 4 weeks old were fed the experimental diets for 3 weeks, and the blood viscosity of the two groups was compared with a Micro Channel Array Flow Analyzer (MC-FAN). The viscosity of heparinized whole blood of the fish oil group was significantly lower than that of the corn oil group, although no significant difference was observed in the deformability of the red blood cells. Frequent platelet aggregations were observed only in the corn oil group in the images of a videocamera equipped with a MC-FAN. The arachidonic acid level in phospholipids of the plasma containing platelet was higher in the corn oil group than in the fish oil group. These findings suggest that the dietary fish oil improved the whole blood viscosity mainly by retarding the platelet aggregation ability, not by increasing the deformability of red blood cell membrane.

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The phase behavior of potassium N-dodecanoyl-DL-alaninate (DL-KDA) and potassium N-dodecanoyl-L-alaninate (L-KDA) in water and water/decanol systems have been investigated. In the DL-KDA/water binary system, normal micellar solution (W_m), hexagonal (H₁), bicontinuous cubic (V₁) phase with Ia3d symmetry, and hydrated solid (S) phases are formed successively with increase in surfactant concentration at 25 °C. The phase behavior of L-KDA is essentially similar to that of the DL-KDA system except that the melting temperature of solid phase is high. In the DL-KDA/water/1-decanol system, lamellar (L_α), reverse hexagonal (H₂) and reverse micellar (O_m) phases are formed successively at 25 °C with increase in 1-decanol concentrations. Addition of decanol to the H1 phase induced a H₁-L_α transformation via intermediate phases. At lower surfactant concentrations, nematic (N) and discotic lamellar (L_α^D) phases are found, whereas at higher surfactant concentrations rectangular ribbon (R₁) and defected lamellar (L_α^H) phases are observed. The L-KDA/water/1-decanol system shows that a chiral nematic or cholesteric (Ch) phase is present (instead of the N phase observed in the DL-KDA system) at low decanol concentrations. However, a similar phase behavior is observed at high decanol concentrations for both surfactant systems. Hence, the optical activity of the surfactant has a significant effect on the phase behavior only in the presence of a low amount of decanol. This phenomenon has been explained by the change in the effective cross-sectional area at the aggregate interfaces.

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By spin probe ESR, examination was made of the effects of temperature on aggregate properties of quaternary ammonium salt cationic surfactant solution with sodium salicylate (NaSal) as a function of 1) alkyl chain length and 2) number of 2-hydroxyethyl groups. For detailed study of rod-like micelle fluidity, measurement was made of the ESR spectra of 5NS, 12NS and 16NS incorporated in micelles in aqueous solution of [NaSal]/[HMODA]. The order parameter (S₃₃) for 5NS considerably exceeded that of 16NS. Fluidity about the spin probe 5NS was much less. The hydrophilic layer of rod-like micelles in aqueous solution of [NaSal]/[HMODA] was more rigid compared to the hydrophobic core. The order parameter of 5NS decreased remarkably at 45-55°C but showed no significant change for 12NS and 16NS spin probes. The hyperfine splitting constant of 5NS (aN′), which reflects polarity about a spin probe, decreased remarkably at 45-55°C. Dehydration of 2-hydroxyethyl groups in [HMODA] took place with increase in temperature, with resultant reduction in the hydrophilicity of [HMODA]. For rod-like aggregates in aqueous solution of [NaSal]/[HMODA], a clear transition temperature was noted, which increased with alkyl chain length and the number of 2-hydroxyethyl groups in cationic surfactants.

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Cubic phases formed in surfactant or copolymer solutions are optically-isotropic and highly viscous liquid crystals. They are mainly categorized to four types; normal micellar discontinuous (I₁), reverse micellar discontinous (I₂), normal bicontinuous (V₁), reverse bicontinuous (V₂) cubic phases. We used both water- and oil-soluble dye solutions to specify the type of cubic phase by a simple dyeing method. Water-soluble dye (Tartrazine) colors I₁ phase, whereas it remains on the top of I₂ phase. Oil-soluble dye (Sudan III) shows the opposite phenomena. Both dyes do color the V₁ and V₂ phases in binary water-surfactant systems. In the presence of oil, the water-soluble dye colors the V₁ phase faster than the V₂ phase. The oil-soluble dye shows the opposite rate of dyeing to bicontinuous cubic phases.

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We attempted to evaluate the hardness of lipid bilayer membranes of liposomes by an ultrasound attenuation method and compared the results with these obtained by a representative fluorescence probe method using pyrene. We used multilamellar vesicles type of liposomes prepared by Bangham’s method. In the ultrasound attenuation method, the measurement of the ultrasonic attenuation constant of liposomes dispersions indicated that the hardness of the bilayer membranes of the liposomes increased with the increasing cholesterol concentration and the decreasing temperature. This tendency was identical with that found in the results obtained by the fluorescence probe method using pyrene. Therefore, we consider that the ultrasound attenuation method is useful for estimating the hardness of lipid bilayer membranes of multilamellar vesicles type of liposomes.

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The lipid class and fatty acid composition in eggs of Indian fresh water common carp Cyprinus carpio (Var. Cummunis Linnaeus) have been studied. The mean wet weight of mature eggs are 4.1% of total weight of fish, of which 9.8% (on dry basis) is lipid. The major portion of the lipid is phospholipid (PL), about 64.3%, of which phosphatidylcholine (PC) is predominant. The fatty acid composition of the total lipid, triacylglycerol (TAG) and phospholipids are observed. Palmitic acid (16:0) is the most abundant saturated fatty acids present in the total lipid (24.2%), TAG (33.2%) and PL (27.4%) fractions. Polyunsaturated fatty acids (PUFA) are more accumulated in the PL fraction than in the TAG. Arachidonic acid (20:4 n-6, AA) and docosahexaenoic acid (22:6 n-3, DHA) in the PL fraction are 13.0% and 15.2% and in TAG fraction 0.6% and 1.0%, respectively. The results of the study indicate that C. carpio eggs are rich in PUFAs which are very much essential in terms of fertilization success and larval development.

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Polar lipids (PL) concentrate was prepared from total lipids (TL) of salmon roe in order to use for highly unsaturated fatty acids (HUFA) enricher of Artemia nauplii, an important live food for marine fish larvae. The PL were concentrated by a solvent partition procedure using a solvent system of equilibrated hexane, ethanol and water. Starting with 120 g of TL, the solvent partition procedure resulted in 29.3 g (27.2 %) of the salmon roe PL concentrate. Major components of the concentrate were phosphatidylcholines (PC; 80.0 %), phosphatidylethanolamines (PE; 7.0 %), and phosphatidylinositols (PI; 5.5 %). Lesser amounts of free fatty acids, sterols and monoacylglycerols were also found in the PL concentrate. Fatty acid analysis revealed the contents of docosahexaenoic acid (DHA; 26.9 %), icosapentaenoic acid (IPA; 14.2 %), and arachidonic acid (AA; 2.4 %). PC and PE isolated from the concentrate were rich in DHA and IPA, whereas PI were rich in AA. The salmon roe PL concentrate appeared to have a potential as an effective HUFA enricher of Artemia nauplii. The solvent partition procedure seems to be useful for convenient preparation of such fish roe PL concentrate.

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