John G. Bieri

Medical Uses of Vitamin E

This review discusses the rationale for vitamin E therapy in medical conditions in which the vitamin may have positive clinical effects. It should be recognized at the outset that nutritional inade...

Determination of Individual Carotenoids in Human Plasma by High Performance Liquid Chromatography

Abstract A high performance liquid chromatography procedure using an internal carotenoid standard, echinenone, is described. The method uses a C-18, reverse-phase column, an isocratic solvent (acetonitrile:methylene chloride:methanol, 70:20:10) and requires only thirteen minutes. Most human plasmas gave seven distinct peaks; six carotenoids are identified. The sum of seven peaks is 90 percent or more of the total carotenoids in a total lipid extract.

The Occurrence and Effects of Human Vitamin E Deficiency: A STUDY IN PATIENTS WITH CYSTIC FIBROSIS

The role of vitamin E in human nutrition was studied by investigation of patients with cystic fibrosis (CF) and associated pancreatic insufficiency. Vitamin E status was assessed by measurement of the plasma concentration of the principal circulating isomer, alpha-tocopherol. Results of such determinations in 52 CF patients with pancreatogenic steatorrhea revealed that all were deficient in the vitamin. The extent of decreased plasma tocopherol varied markedly but correlated with indices of intestinal malabsorption, such as the serum carotene concentration and percentage of dietary fat absorbed. Supplementation with 5-10 times the recommended daily allowance of vitamin E in a water-miscible form increased the plasma alpha-tocopherol concentrations to normal in all 19 CF patients so evaluated. Studies on the effects of vitamin E deficiency focused on possible hematologic alterations. An improved technique was developed to measure erythrocyte hemolysis in vitro in the presence of hydrogen peroxide. While erythrocyte suspensions from control subjects demonstrated resistance to hemolysis during a 3-h incubation, all samples from tocopherol-deficient CF patients showed abnormal oxidant susceptibility, evidenced by greater than 5% hemoglobin release. The degree of peroxide-induced hemolysis was related to the plasma alpha-tocopherol concentration in an inverse, sigmoidal manner. The possibility of in vivo hemolysis was assessed by measuring the survival of (51)Cr-labeled erythrocytes in 19 vitamin-E deficient patients. A moderate but statistically significant decrease in the mean (51)Cr erythrocyte half-life value was found in this group. Measurement of erythrocyte survival before and after supplementation of 6 patients with vitamin E demonstrated that the shortened erythrocyte lifespan could be corrected to normal with this treatment. Other hematologic indices in deficient subjects, however, were normal and did not change upon supplementation with vitamin E. It is concluded that CF is invariably associated with vitamin E deficiency, provided that the patient in question has pancreatic achylia and is not taking supplementary doses of tocopherol. Concomitant hematologic effects consistent with mild hemolysis, but not anemia, occur and may be reversed with vitamin E therapy. Patients with CF should be given daily doses of a water-miscible form of vitamin E to correct the deficiency.

Rat liver α-tocopherol binding protein

Abstract 1. 1. The properties of rat liver cytoplasmic α-tocopherol binding protein have been studied. 2. 2. The binding protein sedimented in the 3 S region of sucrose density gradients, and gel filtration indicated an approximate molecular weight of 30 500. 3. 3. Of the tissues examined by the present assay, binding was detectable only in the liver. 4. 4. Optimal binding was achieved by incubation at 26°C for 4 h and was independent of pH between 7.4 and 9.0. 5. 5. Pronase completely abolished binding. The binding protein was, however, almost completely resistant to trypsin, and unaffected by RNAase, DNAase, triacylglycerol lipase, and phospholipase C. 6. 6. A varietyof tocopherol analogues and other lipid-soluble compounds were tested for their ability to compete for binding. Only α-tocopherol and to a lesser extent α-tocotrienol and γ-tocopherol exhibited competition. α-Tocopherol acetate, γ-tocopherol quinone and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid had no effect on binding. 7. 7. Tocopherol binding was reversible, and the tocopherol was not metabolized during incubation.

Serum Vitamin E Levels in a Normal Adult Population in the Washington, D. C., Area

Summary Serum tocopherol levels in 61 female and 71 male normal adult employees of the National Institutes of Health averaged 1.06 mg/100 ml. No samples were below 0.50 mg/100 ml, and 93.9% were above 0.70 mg/100 ml. A significant correlation was found between serum tocopherol and carote-noids for both males and females.

A comparison of the intestinal absorption, lymph and plasma transport, and tissue uptake of α- and γ-tocopherols in the rat

Abstract 1. 1. The intestinal absorption into lymph of α- and γ-tocopherols was studied in rats with mesenteric lymph cannulae. γ-Tocopherol was consistently absorbed to an extent 15% lower than that of α-tocopherol. Both appeared in the lymph unchanged and were distributed similarly among the lymph lipoproteins. 2. 2. When a mixture of α- and γ-tocopherols bound to chylomicrons and very low density lipoproteins was injected intravenously into rats, the distribution of the two tocopherols in the plasma lipoproteins was similar. A detailed study of the lipo-protein distribution of α-tocopherol, cholesterol, triglyceride and phospholipid in rat plasma revealed that α-tocopherol was not specifically associated with any one lipo-protein group, but that its distribution most nearly resembled that of total lipid. 3. 3. α-Tocopherol and γ-tocopherol after intravenous injection were equally taken up from plasma by red cells and liver, but there was an initial preferential uptake of γ-tocopherol by the spleen. After 24 h, all tissues had lost γ-tocopherol more rapidly than γ-tocopherol.

The roles of vitamin E and unsaturated fatty acids in the visual process.

Relatively high proportions of long-chain, polyunsaturated fatty acids seem to be required in rod photoreceptor membranes in order to provide the precise microenvironment for the proper function of the visual pigment rhodopsin. At the same time, such high levels of lipid unsaturation put the photoreceptor membranes at a high risk for autoxidation. The antioxidant vitamin E which can minimize autoxidation of polyunsaturated fatty acids is found in rather high concentrations in the outer segment membranes. Dietary deficiency in vitamin E induces disintegration of rod outer segment membranes, probably by increasing autoxidation. Also, it greatly accelerates the accumulation of aging pigments in the retinal pigment epithelium, probably because these lipofuscin granules do indeed represent the end products of lipid peroxidation. Vitamin E supplements, up to threefold normal levels, appear to provide no significant protection of the retina from light damage produced either by short but acute or by long-term, low level exposures to light. This is not consistent with current theories which implicate lipid peroxidation in the destruction of rod outer segments in light damaged retinas; more work is needed before any relation between retinal light damage and vitamin E levels can be assessed. Surprisingly, the amount of lipofuscin granule accumulation in the retinal pigment epithelium is influenced dramatically by dietary levels of vitamin A. Even retinas lacking a source of polyunsaturated fatty acids from rod outer segments still may accumulate massive lipofuscin if dietary vitamin A is provided. Perhaps vitamin A, which has such a dynamic relationship with the retinal pigment epithelium, becomes oxidized, and then contributes to the formation of a lipofuscin-like pigment. Centrophenoxine, a drug claimed to be effective in reversing the accumulation of age-related lipofuscin in the central nervous system, has no obvious effect in the eye or uterus in removing the lipofuscin granules induced by vitamin E deficiency. Microperoxisomes are abundant in the retinal pigment epithelium, and may be associated with rapid lipid turnover and/or utilization of lipid soluble vitamins. Their potential roles, however, need further documentation and clarification. Recently developed techniques and new discoveries in lipid research open the way for many fruitful studies on the interactions and precise roles of lipids and lipid-soluble vitamins in vision.

Linoleic acid absorption from lipid supplements in patients with cystic fibrosis with pancreatic insufficiency and in control subjects.

To determine the relative role of malabsorption as the cause of decreased linoleic acid in blood and tissue lipids of patients with cystic fibrosis (CF) and pancreatic insufficiency, the increase in plasma linoleic acid was determined after ingestion of various lipid supplements. CF patients with documented pancreatic insufficiency and normal control subjects were given each of four different lipid supplements on separate days (a minimum of 3 days apart). The supplements were commercial safflower oil, Microlipid, Captex 810D, and Captex 810B. Fasting subjects consumed 36 g of lipid in a milk shake containing 15 g of protein and 45 g of carbohydrate. Plasma samples obtained at 0, 2, 4, 6, and 8 h after the meal showed that CF patients absorbed linoleic acid from all of the lipid preparations tested when administered with their regular dose of pancreatic enzyme supplement. The mean maximal increase in percent plasma linoleic acid in CF patients was not different from controls after ingestion of safflower oil, Microlipid, and Captex 810B. With Captex 810D the CF patients had a significantly higher increase in percent plasma linoleic acid than controls, 6.75% vs. 2.27%, respectively, at 2 h (p < 0.01), and 11.10% vs. 4.65% at 8 h(p < 0.01). The CF patients also appeared to absorb the Captex products faster than controls, suggesting that presence of medium chain length fatty acids in these structured lipids facilitated their utilization by CF patients. The results indicate that malab-sorption alone cannot account for the inadequate or marginal essential fatty acid status of CF patients. The fact that linoleic acid was absorbed as well by CF patients as controls in the present study suggests that CF patients in many previous supplementation studies either have not been given sufficient linoleic acid or have used the linoleic acid ingested to meet caloric needs. There is increasing evidence that adequate total caloric intake may be a far more important factor in determining the essential fatty acid status of CF patients than previously recognized. Our results suggest that long-term consumption of supplemental linoleic acid in addition to adequate caloric intake should improve the linoleic acid status of most, if not all, CF patients.

Serum Vitamin E Determined by Thin-Layer Chromatography

Summary Forty normal adult sera were analyzed by one-dimensional TLC. The averages in mg/100 ml were: α-tocopherol, 0.916; combined β + γ-tocopherols, 0.133. No δ-tocopherol was found. The procedure was checked by comparing with GLC analyses and also with 2-dimensional TLC.

On the occurrence of α-tocopherolquinone in rat tissue

The amount of α-tocopherolquinone in rat liver has been reinvestigated comparing (a) a conventional procedure including saponification and thin layer chromatography followed by high peformance liquid chromatography (HPLC), with (b) the direct HPLC analysis of a total lipid extract. Recovery of added α-tocopherolquinone was quantitative with both procedures. In contrast to a recent report of 124 nmol/g in rat liver, we found no more than 1–4 nmol/g by procedure a and less than 1 nmol/g by procedure b.