Effects of dietary n-3 fatty acids on the phospholipid molecular species of monkey brain

We examined the changes in the molecular species of brain ethanolamine glycerophospholipids of monkeys fed diets containing widely ranging amounts of n-3 fatty acids. Two groups of rhesus monkeys were fed pre- and postnatally either a control diet (soy oil; containing 8% of fatty acids as 18:3n-3) or a deficient diet (safflower oil; containing less than 0.3% 18:3n-3). The brains of these animals were analyzed at 22 months of age. A third group of monkeys was fed the safflower oil diet to 22 months of age and then switched to a fish oil diet (28% long-chain n-3 fatty acids) for 1-2 years before autopsy. The molecular species of the diacyl, alkylacyl, and alkenylacyl ethanolamine glycerophospholipids from frontal cortex were separated by HPLC. A total of 24 molecular species were identified. Fatty acids in the sn-2 position differed markedly among the diet groups, but the sn-1 position always contained only 16:0, 18:0, or 18:1. In the diacyl subclass of the control brain, the n-3 molecular species represented 41% of total and the n-6 species 45%, whereas in the deficient brain the n-3 molecular species decreased to 9% and n-6 molecular species increased to 77%. The fatty acid 22:5n-6 did not replace 22:6n-3 in a symmetrical fashion in the molecular species of the deficient brain. In the brains of the fish oil-fed monkeys, the n-3 molecular species amounted to 61% and n-6 molecular species were reduced to 25%. The species 18:1-22:6, 16:0-22:6, and 18:0-22:6 generally changed proportionally in response to diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of lymphocyte blastogenesis to mitogens in cats experimentally infected with feline immunodeficiency virus

Lymphocytes from normal cats or cats experimentally infected with feline immunodeficiency virus (FIV) were stimulated with phytohemagglutinin, pokeweed mitogen, or concanavalin A. Lymphocytes from infected cats had lower responses than those from uninfected cats. These results support the hypothesis that FIV induces immunosuppression.

Feline immunodeficiency virus, feline leukaemia virus, Toxoplasma gondii, and intestinal parasitic infections in Taiwanese cats

A population consisting of 70 breeder cats, 43 clinical cases, and 16 feral cats was examined for the presence of Toxoplasma gondii, feline immunodeficiency virus (FIV), and feline leukaemia virus (FeLV). No oocysts of T. gondii were observed in 96 faecal samples; faecal samples were not available from the feral cats. Other intestinal parasites identified included Isospora felis (three cats), Isospora rivolta (five), Dipylidium canium (two), Toxocara cati (four), Toxascaris leonina (one), and Ancylostoma sp. (two). Using a kinetics-based enzyme-linked immunosorbent assay on 117 sera including all the feral cats, nine had antibody to T. gondii antigen, three for antigens to FIV, and seven to the p27 antigen of FeLV. Of the nine cats with antibody to T. gondii, only one was also infected with FIV.

Are the n-3 fatty acids from dietary fish oil deposited in the triglyceride stores of adipose tissue?

Adipose tissue is the chief reservoir of the essential fatty acids (n-3 and n-6). To study the incorporation of the dietary n-3 fatty acids eicosapentaenoic acid (EPA) (20:5) and docosahexaenoic acid (DHA) (22:6), and a unique monounsaturated fatty acid, cetoleic acid (22:1n-11), into adipose tissue, rabbits were fed two different processed fish oils: MaxEPA (high in EPA and DHA; Seven Sea Ltd, Hull, UK) and herring oil (high in cetoleic acid). EPA and DHA increased from 0% of total adipose tissue fatty acid, in the adipose tissue of control rabbits to 2.2% and 4.9%, respectively, in MaxEPA-fed rabbits. The DHA-to-EPA ratio in the adipose tissue was higher than that in the diet, indicating alternative metabolic pathways for EPA. In the adipose tissue of herring-oil-fed rabbits, cetoleic acid increased from 0% to 7.9% of total fatty acids. The deposition of EPA and DHA was 1.8% and 2.8%, respectively. Our data indicated that these unique long-chain unsaturated fatty acids from dietary fish oils were readily incorporated into the fat stores from whence they could be mobilized.

Dietary effects on brain fatty acid composition: the reversibility of n-3 fatty acid deficiency and turnover of docosahexaenoic acid in the brain, erythrocytes, and plasma of rhesus monkeys

Rhesus monkeys given pre- and postnatal diets deficient in n-3 essential fatty acids develop low levels of docosahexaenoic acid (22:6 n-3, DHA) in the cerebral cortex and retina and impaired visual function. This highly polyunsaturated fatty acid is an important component of retinal photoreceptors and brain synaptic membranes. To study the turnover of polyunsaturated fatty acids in the brain and the reversibility of n-3 fatty acid deficiency, we fed five deficient juvenile rhesus monkeys a fish oil diet rich in DHA and other n-3 fatty acids for up to 129 weeks. The results of serial biopsy samples of the cerebral cortex indicated that the changes of brain fatty acid composition began as early as 1 week after fish oil feeding and stabilized at 12 weeks. The DHA content of the phosphatidylethanolamine of the frontal cortex increased progressively from 3.9 +/- 1.2 to 28.4 +/- 1.7 percent of total fatty acids. The n-6 fatty acid, 22:5, abnormally high in the cerebral cortex of n-3 deficient monkeys, decreased reciprocally from 16.2 +/- 3.1 to 1.6 +/- 0.4%. The half-life (t 1/2) of DHA in brain phosphatidylethanolamine was estimated to be 21 days. The fatty acids of other phospholipids in the brain (phosphatidylcholine, -serine, and -inositol) showed similar changes. The DHA content of plasma and erythrocyte phospholipids also increased greatly, with estimated half-lives of 29 and 21 days, respectively. We conclude that monkey cerebral cortex with an abnormal fatty acid composition produced by dietary n-3 fatty acid deficiency has a remarkable capacity to change its fatty acid content after dietary fish oil, both to increase 22:6 n-3 and to decrease 22:5 n-6 fatty acids. The biochemical evidence of n-3 fatty acid deficiency was completely corrected. These data imply a greater lability of the fatty acids of the phospholipids of the cerebral cortex than has been hitherto appreciated.

Rapid modulation of the n-3 docosahexaenoic acid levels in the brain and retina of the newly hatched chick

The newly hatched chick obtains its fatty acids almost completely from the lipids of the egg yolk as these are transferred to the developing embryo during its 21-day period of incubation. Since the diet of the laying hen greatly influences the fatty acid composition of the egg lipids, and presumably also the fatty acid composition of the resulting chick, we tested how quickly and to what extent varying the amount of n-3 fatty acids in the diet of the hen would modulate the level of n-3 fatty acids in the brain and retina of the newly hatched chick. White Leghorn hens were fed commercial or semi-purified diets supplemented with 10% fish oil, linseed oil, soy oil, or safflower oil. Eggs, together with the brain, retina, and serum of newly hatched chicks, were then analyzed for fatty acid composition. The fatty acids of egg yolk responded quickly to the hen's diet with most of the change occurring by 4 weeks. There was a linear relationship between the linolenic acid content of the diets and levels of this fatty acid in egg yolk and chick serum. In chicks from hens fed the fish oil diet, the total n-3 fatty acids, including 22:6(n-3), were elevated twofold in the brain and retina and sevenfold in serum relative to commercial diet controls. The safflower oil diet led to a very low n-3 fatty acid content in egg yolks and only 25% of the control n-3 fatty acid content in the brain and retina of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal metabolism of shellfish sterols in a patient with sitosterolemia and xanthomatosis

Sitosterolemia and xanthomatosis together are a disease characterized by premature cardiovascular disease, and by elevated plasma concentrations of total sterols and of plant sterols, especially sitosterol which is hyperabsorbed. In order to determine whether this abnormal metabolism also involved other sterols, a patient with sitosterolemia was fed a diet high in shellfish that contain significant quantities of noncholesterol sterols, some of which are less well absorbed than cholesterol in humans. Compared with control subjects (n = 8), the sitosterolemic subject had an increased absorption of 22-dehydrocholesterol (71.5% vs. 43.8 +/- 11.4%, mean +/- SD), C-26 sterol (80.6% vs. 49.3 +/- 11.4%), brassicasterol (51.8% vs. 4.8 +/- 4.2%), and 24-methylene cholesterol (60.5% vs. 16.0 +/- 8.3%). This enhanced absorption was associated with an increased plasma total shellfish sterol level (13.1 mg/dl vs. 1.9 +/- 0.7 mg/dl in normals). In the sitosterolemic subject, as in normals, the shellfish sterols were not preferentially concentrated in any lipoprotein class, and 50-65% of these sterols were in the esterified form in plasma. Bile acids and neutral sterols were quantitated in bile obtained by duodenal aspiration. The bile acid composition did not differ significantly in the sitosterolemic subject compared with the normal controls. The sitosterolemic subject, though, was unable to concentrate normally the neutral shellfish sterols in bile. The normal controls concentrated the shellfish sterols in bile 6.3 +/- 1.7-fold relative to the plasma shellfish sterol concentration whereas the study subject was only able to concentrate them 2.1-fold. We propose that sitosterolemia and xanthomatosis occur from a generalized abnormality in the usual ability of the gut mucosa and other tissues of the body to discriminate among many different sterols. This has important implications for the understanding of the pathophysiology of this disease and for therapeutic recommendations.

Biochemical and functional effects of prenatal and postnatal omega 3 fatty acid deficiency on retina and brain in rhesus monkeys

Docosahexaenoic acid [22:6 omega 3; 22:6-(4,7,10,13,16,19)] is the major polyunsaturated fatty acid in the photoreceptor membranes of the retina and in cerebral gray matter. It must be obtained either from the diet or by synthesis from other omega 3 fatty acids, chiefly alpha-linolenic acid (18:3 omega 3). We tested the effect of dietary omega 3 fatty acid deprivation during gestation and postnatal development upon the fatty acid composition of the retina and cerebral cortex and upon visual function. Rhesus monkeys (Macaca mulatta) were fed semipurified diets very low in 18:3 omega 3 throughout pregnancy, and their infants received a similar diet from birth. A control group of females and their infants received a semipurified diet supplying ample 18:3 omega 3. In near-term fetuses and newborn infants of the deficient group, the 22:6 omega 3 content of phosphatidylethanolamine was one-half of control values in the retina and one-fourth in cerebral cortex. By 22 months of age, the content of 22:6 omega 3 in these tissues approximately doubled in control monkeys, but it failed to increase in the deficient group. Low levels of 22:6 omega 3 in the deficient animals' tissues were accompanied by a compensatory increase in longer-chain omega 6 fatty acids, particularly 22:5 omega 6. Functionally, the deficient animals had subnormal visual acuity at 4-12 weeks of age and prolonged recovery time of the dark-adapted electroretinogram after a saturating flash. Abnormally low levels of 22:6 omega 3 may produce alterations in the biophysical properties of photoreceptor and neural membranes that may underlie these functional impairments. The results of this study suggest that dietary omega 3 fatty acids are retina and brain.

The absorption of cholesterol and the sterol balance in the Tarahumara Indians of Mexico fed cholesterol-free and high cholesterol diets

The Tarahumara Indians of Mexico are habituated to a very low cholesterol, low fat diet and have lifelong low plasma cholesterol concentrations. To study cholesterol metabolism in these unusual people, 8 Tarahumara men were fed sequentially a cholesterol-free diet and then a diet containing 900 mg cholesterol under controlled conditions. The intestinal absorption of cholesterol, fecal steroid excretion and sterol balance were determined. During the high cholesterol diet period, the plasma cholesterol level increased from 113 +/- 8 mg/dl to 147 +/- 11 mg/dl (means +/- SD). Cholesterol biosynthesis decreased from 14.0 +/- 0.7 to 7.1 +/- 1.0 mg/kg/day (means +/- SE). The intestinal absorption of cholesterol was 27.7 +/- 6.7% (means +/- SE) during both dietary periods. Compared to other cultures, Tarahumaras had a reduced ability to absorb dietary cholesterol and higher total sterol turnover primarily because of an increased bile acid output. The total sterol disposition over three weeks of the high cholesterol diet accounted for all the absorbed dietary cholesterol.

Diffuse bone metastases in a case of astrocytoma

Presented is an unusual case of astrocytoma with diffuse multiple bony metastases in bone imaging. The classification, spread, and prognosis of astrocytoma are briefly reviewed.

Lymphomatous intracardiac mass detected by radionuclide ventriculography

A case of non-Hodgkin's lymphocytic lymphoma with cardiac involvement shown as an intracardiac-filling defect on the radionuclide ventriculogram is presented. The non-invasive diagnostic methods for cardiac lymphoma work-up are discussed. The known causes of cardiac-chamber filling defect(s) are reviewed.

Sterol composition of normal human bile. Effects of feeding shellfish (marine) sterols

To examine the sterol composition of normal human bile and the effects of dietary components from certain shellfish upon bile composition, we fed 7 subjects diets rich in shellfish for 2 wk following a typical American diet. The total cholesterol, bile acid, and phospholipid, and the individual sterols and bile acids of the bile samples during each dietary period were measured. In the bile of 7 subjects consuming the typical American diet, nine different neutral sterols, in addition to cholesterol, were identified. Similar patterns of these sterols have been found in human gallstones and in plasma after shellfish feeding. The five shellfish sterols (22-dehydrocholesterol, 24-methylene cholesterol, brassicasterol, isofucosterol, and a C-26 sterol) increased from 0.3% to a total of 5.2% (p less than 0.001) of total sterols. A comparison of the ratios of various shellfish sterols to cholesterol in plasma and in bile suggested selectively greater excretion of shellfish sterols relative to cholesterol. Our data demonstrated that human bile contains a mixture of sterols and that its sterol composition can be readily altered by dietary changes. The lithogenicity of the bile based on the ratio of cholesterol, bile acids, and phospholipids, and the bile acid composition was not affected by the presence of shellfish sterols. However, since some of these sterols occur in human gallstones, their lithogenic capacity cannot be ruled out.

Ga-67 cardiac uptake

A case of positive Ga-67 image due to tuberculous pericarditis is presented. The pattern and distribution of the uptake suggested that the concentration of the activity was mainly in the inflamed pericardium. The known causes of Ga-67 cardiac uptake were reviewed, and a differential diagnosis is given.

Lipids of human atherosclerotic plaques and xanthomas: clues to the mechanism of plaque progression

While the content of fatty streaks and fibrous plaques has been extensively studied in autopsied specimens, little is known about the lipid composition of advanced human atherosclerotic plaques requiring surgical removal. We have analyzed free cholesterol, cholesteryl ester, and the cholesteryl ester fatty acid content in 19 carotid and 7 femoral obliterative plaques obtained at endarterectomy. These were compared with values from each subject's plasma and from xanthomas removed from eight patients. The total cholesterol content was 75.1 mg/g dry weight for carotid plaques, 56.0 mg/g for femoral plaques, and 106.8 mg/g for xanthomas. The free cholesterol content was 56.6% and 50.4% of the total cholesterol for carotid and femoral plaques, respectively, while the free cholesterol of xanthomas was only 25.5%. The fatty acids of cholesteryl esters were analyzed in an attempt to identify the site of their esterification, i.e., within plasma or within plaque. This can be determined using the ratio of linoleic acid (18:2) to oleic acid (18:1) in the cholesteryl ester. The ratios were 0.36 for xanthoma, 1.62 for carotid plaque, 1.73 for femoral plaque, and 2.51 in plasma. These data emphasize two chemical changes occurring with evolution of the atherosclerotic process: 1) The cholesteryl ester fatty acid composition of the plaque becomes increasingly similar to that of plasma, and 2) there is a continuing increase in the percentage of free cholesterol. These alterations reflect a decreased metabolic efficiency within atherosclerotic lesions and may initiate events that enhance plaque progression.

Delayed renal localization of Ga-67: concise communication

Five hundred Ga-67 images, requested for detection or follow-up of inflammatory or neoplastic diseases, were reviewed to evaluate the incidence of delayed renal localization and the clinical significance of different degrees of uptake. Renal uptake in 48- or 72-hr images was graded as follows: 0 = background activity; 1+ = greater than background but less than spine; 2+ = close to spine but less than liver; 3+ = same as liver; 4+ = greater than liver. On the 500 images, 996 kidneys were evaluated and among them 600 (60%) had 0 uptake and 340 (34%) had 1+. These 940 kidneys were all considered to be normal. Fifty-six (6%) had 2+ or more uptake, with possible causes for uptake being: infection 27, drug-induced renal damage ten, urinary stasis or slow excretion seven, collagen vascular disease six, renal failure four, acute tubular necrosis one (ATN), and indeterminate one. Cases of renal infection or failure tended to show more or less 4+ uptake, while drug damage, ATN, or urinary stasis tended to have 2+ uptake.

"Hot" spleen on Tc-99m sulfur colloid images

In routine Tc-99m sulfur colloid (SC) liver-spleen imaging, relatively increased splenic uptake when compared with liver uptake is frequently seen. Commonly this is due to decreased hepatic uptake secondary to liver disease, but often it is because of increased uptake in the hyperfunctioning spleen. Reported is a case of lymphoma of the tonsil, with a "hot" spleen which was free of tumor. Possible etiology of the "hot" spleen is discussed and the known causes listed according to their prevalence.

Comparative lymphatic absorption of sitosterol, stigmasterol, and fucosterol and differential inhibition of cholesterol absorption

Studies have been conducted on the lymphatic absorption of sitosterol (24 alpha-ethyl cholesterol), stigmasterol (delta 22, 24 alpha-ethyl cholesterol), and fucosterol (24-ethylidine cholesterol) when administered intragastrically to rats. In addition, the effect of each sterol on absorption of endogenous cholesterol has been assessed by including tracer cholesterol in the administered test emulsion. Analysis of 24-h lymph collections by GLC-mass spectrometry demonstrated that all three sterols were poorly absorbed to the extent of only 3 to 4% of the administered dose of 50 mg. In contrast, cholesterol absorption under similar conditions was about 42% of the administered dose. Administration of either sitosterol or stigmasterol resulted in an equally effective inhibition of cholesterol absorption (54%). Under identical conditions fucosterol had no effect on absorption of luminal cholesterol. The data suggest that the mechanism(s) for intestinal discrimination of sterols for absorption may be independent of the mechanism for interference with efficient cholesterol uptake by the intestine.

The origin of plant sterols in the skin surface lipids in humans: from diet to plasma to skin

To test the hypothesis that plant sterols found in the skin surface lipids of humans originated from diet after their absorption from intestine into plasma and then transferred to skin, we studied the 24-h excretion of plant sterols and cholesterol from skin and in feces in a hyperlipoproteinemic (type IIa) patient fed formula diets providing varying quantities of plant sterols (0-30 g/day) and cholesterol (0-1000 g/day). Upon feeding a sterol-free diet, the beta-sitosterol excretion from the skin decreased progressively, from about 6 mg/day to 0.08 mg/day by 83 days and then completely disappeared. With addition of plant sterols (about 30 g/day) to the diet, beta-sitosterol reappeared in the skin surface lipids and rose to nearly 5 mg/day by 6 weeks. With feeding of the sterol-free diet, the fecal excretion of beta-sitosterol and the 2 other plant sterols decreased gradually and by week 4 disappeared completely from the feces and continued to be absent from the feces as long as the diet was free of plant sterols. The results demonstrated clearly that plant sterols which were absorbed into the plasma from the diet were excreted into the skin surface lipids after being transferred from the plasma to the skin.

The effect of shellfish in the diet upon the plasma lipid levels in humans

In order to document any hypercholesterolemic effects from the ingestion of shellfish, 6 normal men were given two diets containing different shellfish, each preceded by a low cholesterol baseline diet. Diet I contained 449 mg cholesterol per day from lobster, crab, and shrimp. Diet II contained clam, oyster, and scallop and provided 447 mg of sterols of which cholesterol constituted only 40 percent. The other sterols are uniquely characteristic of these shellfish (i.e. brassicasterol, 24-methylene cholesterol, etc.). In a second study, 2 normal men and 1 type II hypercholesterolemic woman were fed the baseline diet and shellfish diet II to provide 623 mg of sterols per day. The plasma cholesterol of the 6 subjects averaged 184 +/- 35 mg/dl during baseline, 192 +/- 35 mg/dl in shellfish diet I (p less than 0.05) and 182 +/- 24 mg/dl during shellfish diet II. In the second study, the plasma cholesterol of the 2 normal men did not change. The cholesterol of the hypercholesterolemic woman increased from 311 mg/dl (baseline) to 352 during the shellfish diet (p less than 0.05). Plasma triglyceride levels remained unchanged. Our data indicated that large quantities of lobster, crab, and shrimp were only mildly hypercholesterolemic in normals, but less so than other cholesterol-containing foods. Clams, oysters, and scallops were not hypercholesterolemic in normal subjects but were in a hypercholesterolemic patient.