Dietary fat effect on incorporation and release of lipids and cholesterol by rat intestinal slices

The effect of saturated and unsaturated fats on in vitro formation and release of lipids and cholesterol from¹⁴C acetate by rat intestinal tissue was investigated. The rats were fed a basal diet enriched with either 25% corn oil or lard and then sacrificed after a 10- or 25-day feeding period. It was observed that a similar¹⁴C lipid content but a greater¹⁴C cholesterol content was found in the intestinal tissue of rats fed corn oil than in rats fed lard for 10 days. After a longer period of feeding of 25 days, the intestinal tissue¹⁴C cholesterol level was decreased in the corn oil fed rats without any significant effect on other lipids. These data suggest that corn oil in some way influences cholesterol biosynthesis depending upon its degree of unsaturation and the period of time for which it is fed. The decrease at the later time might involve some mechanism which aids in getting rid of accumulated tissue cholesterol. Less¹⁴C lipid and¹⁴C cholesterol were released by the intestinal tissue of rats fed the unsaturated fat as compared with those fed the saturated fat, suggesting a possible role in vivo in reducing blood lipids and blood cholesterol levels. Robert A. Welch Foundation.     

The incorporation of ethanolamine into ether-containing lipids in rat brain

After intracerebral injection of C¹⁴-ethanolamine into rats, the ethanolamine phosphoglycerides were isolated and hydrolyzed with mild alkali and acid. The specific radioactivity of the diacyl, acyl alkenyl, and acyl alkyl glyceryl-3-phosphorylethanolamine, the diacyl and acyl alkenyl glyceryl-3-phosphorylcholine, and sphingomyelin was determined at 0.5, 2, 24, and 48 hours. The specific radioactivity-time relationships show that the ethanolamine plasmalogen is not a precursor for the glyceryl ether form but suggest that acyl alkyl glyceryl-3-phosphorylethanolamine is desaturated to form some of the acyl alkenyl glyceryl-3-phosphorylethanolamine. The radioactivity in the choline portion of the choline phospholipids was very low. Presented at the AOCS Meeting, Cincinnati, October 1965.     

Monoenoic fatty acids in human brain lipids: Isomer identification and distribution

The carbon chain length distribution and the double bond positional isomer composition of the monoenoic fatty acids of the lipids of total human brain tissue have been determined using gas chromatography and gas chromatography/mass spectrometry of the fatty acid methyl and picolinyl esters. The even chain length monoenoic C₁₆ to C₂₈ fatty acids contain predominantly two positional isomer series, the n−7 and n−9cis homologues, whose relative proportion varies significantly with chain length. The odd chain length long-chain fatty acids consist of n−8 and n−10 isomers, whereas the odd chain length very long-chain (more than 22 carbon) fatty acids are n−7 and n−9 isomers.     

Metabolism of lipids in rat testes: Interconversions and incorporation of linoleic acid into lipid classes

Studies are reported on the mode of incorporation of linoleic acid into lipid classes of testicular lipids. 1-¹⁴C-linoleic acid was injected into the testes of adult rats of the Sprague-Dawley strain. Groups of animals were killed at 1, 3, 6, 12, 24 and 48 hr after injections of the radioactive linoleic acid. The testes of each animal and livers of some animals were excised. Fatty acid and lipid class comkposition of the extracted lipids of the testes of each animal were determined as well as the distribution of radioactvity in these compounds. Radioactive linoleic acid and fatty acids derived from it by interconversion and catabolism were incorporated into all the lipid classes. Incorporation of linoleic acid into the lipid classes was much faster than its interconversion or catabolism to other fatty acids. The importance of the fatty acid pool in the mode of incorporation of the fatty acids into the lipid classes is demonstrated.     

Measurement of the incorporation of orally administered arachidonic acid into tissue lipids

The applicability of a stable isotope method to monitor the mixing of dietary arachidonic acid with endogenous arachidonic acid in tissue lipids was evaluated. Rats were fed octadeuterated arachidonic acid during a 20-day period, and the entry of the dietary acid into lipid esters of various tissues was examined by gas chromatographymass spectrometric (GC-MS) analysis of their fatty acids. The rats were maintained on a fat-free diet from weaning until 63 days old to enhance the ratio of the dietary acid to endogenous arachidonate. Three separate forms of eicosatetraenoic acid in the tissue lipids could be distinguished by GC-MS: octadeuterated arachidonic acid (recent dietary origin), unlabeled arachidonic acid (maternal origin) and unlabeled, 4,7,10,13-eicosatetraenoic acid (originating from palmitoleic acid). The total eicosatetraenoic acid in the tissue lipids contained about 90% arachidonate from recent dietary origin in lung, kidney, heart and fat, 70% in muscle and liver and 27% in brain. The n−7 isomer of eicosatetraenoic acid was estimated to make up 6% or less of the total eicosatetraenoic acid in lung, kidney, brain, muscle and heart tissue lipids, but it comprised around 15% of the total eicosatetraenoic acid in liver. The unlabeled arachidonic acid of maternal origin thus comprised only about 10% of the eicosatetraenoic acid in all tissues examined except muscle and brain, where it was 24% and 70% of the eicosatetraenoic acid, respectively. The relative amounts of the three forms of eicosatetraenoic acid are consistent with a limited access of dietary arachidonate to the brain tissue and with a competition between the dietary n−6 isomer and the endogenous n−7 isomer for esterification in the liver. Because most muscle mass would have formed after weaning, the high proportion of maternal arachidonate in the muscle lipids suggested that maternal arachidonate may have been displaced from other tissues to muscle, from which it equilibrated slowly with dietary arachidonate acid. The combination of deuterated arachidonic acid and GC-MS analysis thus furnished more detailed information about the composition and origin of eicosatetraenoic, acid in tissue lipid esters than that previously available from radiotracer studies or GC-MS analyses alone.     

Ultrasonography measurement of intrabdominal visceral fat in obese men. Association with alterations in serum lipids and insulinemia

Abdominal obesity and specifically intrabdominal adiposity leads to increase in cardiometabolic risk factors (CMR), independently of body mass index (BMI). In order to examine CMR factors associated with the presence of visceral fat (VF) in individuals with different degrees of overweight/obesity, 154 men, 20 to 60 years of age, attending a at an Industrial Clinic in Venezuela, were evaluated. Ultrasound was used to establish the presence and amount of VF. As expected, VF values were higher as the BMI increased. It was observed that VF was associated positive and significantly with age, abdominal circumference and the degree of insulin resistance (HOMA-IR) in subjects with normal weight as well as in those with overweight and obesity. However, BMI was correlated with VF only in those with normal weight or overweight. In the obese a positive correlation was observed between VF with glycemia and triglycerides, while insulin was correlated with VF only in the subjects with normal weight. Based on the ROC curves, and taking as cut-off point for VF a value of 6 cm, it was possible to predict the presence of hyperglycemia with a 58.6% of sensitivity and 77% of specificity, presence of insulin resistance with 54 % of sensitivity and 78 % specificity, hypertriglyceridemia with 39% of sensitivity and 78% specificity and low HDLc with 45% sensitivity and 77% specificity. The area under the curve for the ROC analysis was greater for visceral fat compared with abdominal circumference for hyperglicemia (0.727 vs. 0.693, p < 0.05) and hypertrigliceridemia (0.678 vs. 0.621, p < 0.05) while the opposite was observed for HOMA-IR (0.74 vs. 0.788, p < 0.05) and for low HDL-c (0.651 vs. 0.668, p < 0.05). We conclude that ultrasound measure of VF, was better in predicting hyperglycemia and hypertriglyceridemia, while abdominal circumference was better predicting insulin resistance and low HDLc and could be useful in the preventive evaluation of individuals at risk for diabetes or cardiovascular disease.     

Comparison of body fat using anthropometry bioelectrical impedance and DEXA in elderly women

Verify correspondence and compare percentage body fat (%BF) estimates by skinfold thickness (SKT), bioelectrical impedance analysis (BIA) and DEXA. Twenty voluntaries women (aged 62-79 yr) were assessed. The body fat was estimated using two different equations of SKT(Jackson (19); Durning and Womersley, (20)), BIA using two-predictions formulas (23) and DEXA. To compare mean values of %BF was used analysis of variance for repeated measures (ANOVA--Bonferroni), the correlation of the inter-method was verified by Pearson correlation coefficients (r), and correspondence between prediction formulas was tested by using the approach by Bland and Altman (25). The %BF assessed by BIA (23) shown poor correlation (r < 0.5) with two SKT equations. The %BF ranged from 31.5 +/- 5.5 to 41.2 +/- 6.1 (mean +/- SD) for Jackson (19) e DEXA, respectively. The analysis of variance shown no significant differences (p > 0.05) between methods and/or equations by BIA (RJL-CompCorp) vs. DC-Jackson (19). There were observed significant differences (p < 0.001) between all comparisons. The correspondence between RJL-CompCorp vs. Deurenberg (23) was good and the same was observed for DEXA vs. Durning and Womersley (20). Although the methods and/or equations used in this study have been commonly utilized to estimate BF in elderly subjects, they neither must be used as a standard method. Each method has limitations and the comparison can be useful for interpretation of results.     

Effect of moderate to very low fat defined formula diets on serum lipids in healthy subjects

Serum total cholesterol, high density lipoprotein (HDL) cholesterol, and triglyceride levels were studied in healthy male and female subjects consuming for one-week periods a diet of conventional food (CF) providing 42% of energy as fat, principally butter fat, and then in random order nutritionally complete, defined formula diets of moderate (32%) to very low (1%) fat content. Compared to CF, the formula with 32% of energy as corn oil lowered serum cholesterol by 25% and the ratio of total to HDL-cholesterol by 13%. Low (9%) and very low (1–3%) fat formulas reduced HDL-cholesterol by as much as 40%, raised the total: HDL-cholesterol ratio by about 20% and raised serum triglyceride levels by as much as 100%. When low and very low fat formulas were ingested for three weeks, these effects persisted although maximal responses occurred during the first week. These results demonstrated that a moderate fat formula diet with a high P/S ratio had a more favorable effect on serum lipid levels than various low fat formulas. Low fat conventional food diets should be studied in long-term controlled metabolic experiments before such diets are recommended to the general population for coronary heart disease or cancer prevention.     

Fatty acid distribution in lipids and32P incorporation into phospholipids during early amphibian development

Several aspects of lipid composition and³²P incorporation were studied during early embryogenesis of the toad,Bufo arenarum, Hensel. The surveyed stages ranged from unfertilized oocyte to neural tube formation. The fatty acid distribution in polar and neutral lipids, as well as in acetone eluate from Unisil columns was similar in unfertilized oocyte and late blastula stage. There was no significant effect of cell cleavage on the fatty acid composition of these lipid fractions. Neutral lipids represent ca. 67% of the total lipids. The main components of the phospholipids were phosphatides of choline and ethanolamine. The total lipid and phospholipid content does not change through the studied stage of neurula. However a large increment in the phospholipid's specific radioactivity occurs when³²P is injected along with the hormone to induce ovulation. It is suggested that this may reflect changes in turnover rates rather than net biosynthesis. Since a large amount of cell membranes is being formed during the early development and because the level of phospholipids remains constant, an explanation is offered regarding membranogenesis. Active phospholipid biosynthesis may take place during oogenesis. These lipids may be stored in the yolk platelet, and fertilization may regulate the functioning of a transport mechanism to corresponding membrane sites. The increased incorporation of³²P may reflect changes in the activity of new membranes.     

Heneicosapentaenoate (21:5n−3): Its incorporation into lipids and its effects on arachidonic acid and eicosanoid synthesis

6,9,12,15,18-Heneicosapentaenoic acid (21:5n-3) (HPA), present in small amounts in fish oils, has been prepared by chemical elongation of eicosapentaenoic acid (EPA) and its biological properties compared with EPA and docosahexaenoic acid (DHA). All the double bonds of HPA are displaced one carbon away from the carboxyl group when compared to EPA. HPA is incorporated into phospholipids and into triacylglycerol in cell culture to a similar extent as EPA and DHA. HPA is a stronger inhibitor of the conversion of α-linoleic acid and dihomo-γ-linolenic acid to arachidonic acid (AA) in hepatoma cells than are EPA, DHA, and AA. HPA is a poor substrate for prostaglandin H synthase and for 5-lipoxygenase, but it inactivates prostaglandin H synthase as rapidly as do AA, EPA, and DHA. HPA inhibits thromboxane synthesis in isolated platelets as efficiently as EPA. EPA, HPA, and DHA are all weak inducers of acyl-CoA oxidase in hepatoma cells. Therefore, since fish oils contain only small amounts of HPA, it is unlikely that this fatty acid is of particular significance for the biological effects of these oils, possibly with the exception that it is a strong inhibitor of AA synthesis.     

Factors affecting incorporation of precursors into body constituents: A review of common sense considerations with glycolipids as examples

The dynamics of cellular growth are of prime importance to the biochemist. The dynamic state of lipids can be studied by employing radioactive substrates or stable isotope-labeled substrates. This paper illustrates major factors which may effect the incorporation of precursor substances into body constitutents. These factors are: (a) age and species; (b) molar size of the body’s pool of precursor; (c) metabolic activity of the lipid being synthesized; (d) metabolic pathways; (e) route of administration of the precursor; (f) the nature of the precursor, i. e., molecular size, ionic or nonionic, water soluble vs. lipid solubility, and micelle formation; and (g) the influence of hormones and drugs. The synthesis and turnover of cerebrosides and gangliosides in the rat are used to illustrate these seven factors.     

Solvent-free enzymatic synthesis of structured lipids containing CLA from coconut oil and tricaprylin

Lipase-catalyzed acidolysis of different TAG with CLA was performed to produce structured lipids (SL) containing CLA. An immobilized lipase from Mucor miehei (Lipozyme IM, Novo Nordisk Inc., Franklinton, NC) was used as the biocatalyst in a solvent-free system. Conconut oil and tricaprylin, which are sources of medium-chain FA, were the starting substrates, and a mixture of FFA (MFFA) containing 73% CLA was the donor of the acyl groups. For each TAG, four different ratios of TAG/MFFA were blended to prepare about 500 g of mixture containing 10, 20, 30, and 40% CLA (w/w). Each blend was reacted with 5% lipase at 65°C for 48 h under nitrogen. Over the range of TAG/MFFA ratios examined, CLA was incorporated effectively by the enzyme. Lipozyme IM exhibited no special preference for any particular FA, since the incorporation of FA was proportional to their concentration in the system. FFA, PV, p-anisidine value (p-AV), iodine value (IV), and saponification number (SN) were evaluated for all the SL. FFA, PV, and p-AV depended on the purification process and showed no significant deterioration of SL with respect to the original TAG, whereas IV and SN depended on the composition of the SL, mainly the CLA content.     

Effect of dietary conjugated linoleic acid (CLA) on metabolism of isotope-labeled oleic,linoleic, and CLA isomers in women

The purpose of this study was to investigate the effect of dietary CLA on accretion of 9c-18∶1, 9c, 12c-18∶2, 10t, 12c-18∶2, and 9c, 11t-18∶2 and conversion of these FA to their desaturated, elongated, and chain-shortened metabolites. The subjects were six healthy adult women who had consumed normal diets supplemented with 6 g/d of sunflower oil or 3.9 g/d of CLA for 63 d. A mixture of 10t, 12c-18∶2-d ₄, 9c, 11t-18∶2-d ₆, 9c-18∶1-d ₈, and 9c, 12c-18∶2-d ₂, as their ethyl esters, was fed to each subject, and nine blood samples were drawn over a 48-h period. The results show that dietary CLA supplementation had no effect on the metabolism of the deuterium-labeled FA. These metabolic results were consistent with the general lack of a CLA diet effect on a variety of physiological responses previously reported for these women. The ²H-CLA isomers were metabolically different. The relative percent differences between the accumulation of 9c, 11t-18∶2-d ₆ and 10t, 12c-18∶2-d ₄ in plasma lipid classes ranged from 9 to 73%. The largest differences were a fourfold higher incorporation of 10t, 12c-18∶2-d ₄ than 9c, 11t-18∶2-d ₆ in 1-acyl PC and a two- to threefold higher incorporation of 9c, 11t-18∶2-d ₆ than 10t, 12c-18∶2-d ₄ in cholesterol esters. Compared to 9c-18∶1-d ₈ and 9c, 12c-18∶2-d ₂, the 10t, 12c-18∶2-d ₄ and 9c, 11t-18∶2-d ₆ isomers were 20–25% less well absorbed. Relative to 9c-18∶1, incorporation of the CLA isomers into 2-acyl PC and cholesterol ester was 39–84% lower and incorporation of 10t, 12c-18∶2 was 50% higher in 1-acyl PC. This pattern of selective incorporation and discrimination is similar to the pattern generally observed for trans and cis 18∶1 positional isomers. Elongated and desaturated CLA metabolites were detected. The concentration of 6c, 10t, 12c-18∶3-d ₄ in plasma TG was equal to 6.8% of the 10t, 12c-18∶2-d ₄ present, and TG was the only lipid fraction that contained a CLA metabolite present at concentrations sufficient for reliable quantification. In conclusion, no effect of dietary CLA was observed, absorption of CLA was less than that of 9c-18∶1, CLA positional isomers were metabolically different, and conversion of CLA isomers to desaturated and elongated metabolites was low.     

The incorporation of glycerol into the glyceride-glycerol of fat cells isolated from chronically cold-exposed rats

The rate of 2-¹⁴C-glycerol incorporation into the glyceride-glycerol moiety was measured in isolated fat cells from control rats maintained at 25 C and from animals chronically exposed to cold (5 C) for six to eight weeks. The rate of glycerol conversion (μM/μg DNA/30 min) was less in the cold-exposed rats, than in comparable controls (1.96±0.14 vs. 2.68±0.17). Very little glycerol was oxidized to CO₂ or converted to fatty acids. In both groups of animals, the glyceride-glycerol formation was apparently stimulated by noradrenaline in the presence of glucose, but this incorporation does not significantly bias the estimation of lipolysis based upon glycerol release. Presented in part at the AOCS Meeting, Washington, D.C., 1968.     

The effect of dietary fat on the fatty acid composition of lipids secreted in rats' milk

During pregnancy and lactation, female rats were fed diets containing either 28% partially hydrogenated marine oil (28MO), 2% arachis oil (2AO), or no fat (FF). Milk lipid composition was examined by gas chromatographic analysis of the gastric content of 10-day-old suckling pups. An increase to 45% in the milk content of long chain monoenoic acids, 18∶1, 20∶1 and 22∶1, reflects the fatty acid composition of the marine oil. Milk fatty acids of medium chain length comprised 6%, 31% and 24% of total fatty acids in the (28MO), (2AO) and (FF) groups, respectively, suggesting that a high-fat diet (28MO) inhibits the lipid synthetic activity of mammary glands. The amount of dienoic C₁₈-acids (6%) in the group fed (28MO) containing no essential fatty acids (EFA) was similar to the amount of 18∶2 in the group receiving a low-fat, EFA-rich diet (2AO). However, only half the dienoic acid from the milk of the (28MO)-fed animals was linoleic acid, which was most likely mobilized from fat depots.     

Effect of androgens on serum lipids and lipoproteins

The effects of androgens on lipid transport and metabolism have been reviewed. These effects are probably independent of the androgenic and anabolic activities of the androgens, although the molecular mechanism of action is still not known. Presumably the lowering by androgens of the concentrations of serum lipids and lipoproteins could be the consequence possibly of a primary, inhibitory effect on the synthesis of apolipoprotein A. In addition the role of increased lipolytic activities in plasma and of effects on intermediatry metabolism has been considered. Special Fellowship Awardee (1F11 NSO2245-01) from the National Institute of Neurological Diseases and Stroke One of eight papers presented at the symposium “Recent Advances in Drugs Affecting Lipid Metabolism,” AOCS Meeting, Houston, May 1971.     

Glycerolipid biosynthesis in rat adipose tissue: VIII. Effect of obesity and cell size on [14C]acetate incorporation into lipids

[¹⁴C]Acetate incorporation into different lipid fractions was measured as a function of adipocyte size by using the larger and smaller adipocytes derived from Sprague-Dawley rats. In both the larger and smaller adipocytes, [¹⁴C]acetate was incorporated into phospholipid, diacylglycerol, free fatty acid and triacylglycerol fractions. Although the rates of lipid formation were significantly higher in the larger adipocytes compared to the smaller ones, the proportions of the various lipids formed from [¹⁴C]acetate did not change significantly as a function of cell size. In some experiments, isolated adipocytes derived from obese Zucker rats were fractionated further to isolate an adipocyte preparation which was similar in size to those obtained from lean animals. The matching adipocytes derived from lean and obese animals did not differ significantly with respect to lipid formation from [¹⁴C]-acetate. These studies suggest that the larger adipocytes are more active in lipogenesis from [¹⁴C]-acetate than the smaller ones and that the increased capacity of lipogenesis in obese adipose tissue noted proviously (Biochem. J., 170, 153–160, 1978) is not an intrinsic property of all the obese adipocytes, but is limited mainly to the larger adipocytes.     

The effect of dietary fat level and quality on plasma lipoprotein lipids and plasma fatty acids in normocholesterolemic subjects

This study examined the effect on the plasma lipids and plasma phospholipid and cholesteryl ester fatty acids of changing from a typical western diet to a very low fat (VLF) vegetarian diet containing one egg/day. The effect of the addition of saturated, monounsaturated or polyunsaturated fat (PUFA) to the VLF diet was also examined. Three groups of 10 subjects (6 women, 4 men) were fed the VLF diet (10% energy as fat) for two weeks, and then in the next two weeks the dietary fat in each group was increased by 10% energy/week using butter, olive oil or safflower oil. The fat replaced dietary carbohydrate. The VLF diet reduced both the low density lipoprotein (LDL)-and high density lipoprotein (HDL)-cholesterol levels; addition of the monounsaturated fats and PUFA increased the HDL-cholesterol levels, whereas butter increased the cholesterol levels in both the LDL- and HDL-fractions. The VLF diet led to significant reductions in the proportion of linoleic acid (18∶2ω6) and eicosapentaenoic acid (20∶5ω3) and to increases in palmitoleic (16∶1), eicosatrienoic (20∶3ω6) and arachidonic acids (20∶4ω6) in both phospholipids and cholesteryl esters. Addition of butter reversed the changes seen on the VLF diet, with the exception of 16∶1, which remained elevated. Addition of olive oil resulted in a significant rise in the proportion of 18∶1 and significant decreases in all ω3 PUFA except 22∶6 compared with the usual diet. The addition of safflower oil resulted in significant increases in 18∶2 and 20∶4ω6 and significant decreases in 18∶1, 20∶5ω3 and 22∶5ω3. These results indicate that the reduction of saturated fat content of the diet (<6% dietary energy), either by reducing the total fat content of the diet or by exchanging saturated fat with unsaturated fat, reduced the total plasma cholesterol levels by approximately 12% in normocholesterolemic subjects. Although the VLF vegetarian diet reduced both LDL- and HDL-cholesterol levels, the long-term effects of VLF diets are unlikely to be deteterious since populations which habitually consume these diets have low rates of coronary heart disease. The addition of safflower oil or olive oil to a VLF diet produced favorable changes in the lipoprotein lipid profile compared with the addition of butter. The VLF diets and diets rich in butter, olive oil or safflower oil had different effects on the 20 carbon eicosanoid precursor fatty acids in the plasma. This suggests that advice on plasma lipid lowering should also take into account the effect of the diet on the fatty acid profile of the plasma lipids.     

A comparative study of the lipids of chylomicron membrane and fat core and of the lymph serum of dogs

Thoracic lymph was collected from 13 dogs fed corn oil and butterfat. The chylomicrons were isolated by centrifugation. The lipid composition of the fat core and the membrane of the chylomicron was compared to that of the surrounding lymph serum. The fat cores contained 90–96% triglyceride, 0.7–1.9% free cholesterol, 0.2–0.5% steryl ester, 0.9–3.5% free fatty acid and 1.4–6.1% diglyceride, but no phospholipid. The lipids of the membranes contained 58–75% phospholipid, 20–35% triglyceride, 2–5% free cholesterol, 1–2% free fatty acid, and 2–3% diglyceride, but little or no steryl ester. The membrane phospholipids were made up of 70–90% lecithin, 5–20% phosphatidyl ethanolamine, and 1–3% each of lysolecithin and sphingomyelin. The lymph serum contained 24–47% of total lipid as phospholipid, of which 70–92% was lecithin; the phosphatidyl ethanolamine, lysolecithin and sphingomyelin also present contributed 1–10% each. The neutral lipids of the lymph serum contained 49–75% triglyceride, 2–15% free cholesterol, 6–23% esterified cholesterol, 10–33% free fatty acid and 1–6% diglyceride. Alterations in dietary fat, or plant sterol supplementation led to lesser changes in the lipids of the chylomicron membranes than in the lipids of any other lymph fraction. The least variation was seen in the phospholipids. Taken in part from a PhD Thesis submitted by T. C. Huang to Queen's University, Kingston, Canada, in April 1965. Presented at the AOCS 56th Spring Meeting, Houston, May 1965.