626
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627
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Kuksis A, Myher JJ, Geher K, Jones GJ, Shepherd J, Packard CJ, Morrisett JD, Taunton OD, Gotto AM. Effect on saturated and unsaturated fat diets on lipid profiles of plasma lipoproteins. Atherosclerosis 1982; 41:221-40. [PMID: 7066072 DOI: 10.1016/0021-9150(82)90187-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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628
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Slater HR, Packard CJ, Shepherd J. Receptor-independent catabolism of low density lipoprotein. Involvement of the reticuloendothelial system. J Biol Chem 1982; 257:307-10. [PMID: 6273431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In this study we examine the effects of intravenous ethyl oleate emulsions on the metabolism of native and cyclohexanedione-modified human low density lipoprotein in rabbits. Treatment produced a highly significant fall in receptor-independent catabolism as measured by the fractional clearance rate of cyclohexanedione-modified low density lipoprotein. Receptor-dependent catabolism (the difference between the fractional clearance rates of native and cyclohexanedione-modified low density lipoprotein) was variably affected with some animals showing a decrease in receptor activity. These data suggest that the reticuloendothelial system makes a substantial contribution to receptor-independent low density lipoprotein catabolism in the rabbit.
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629
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Slater HR, Packard CJ, Shepherd J. Measurement of receptor-independent lipoprotein catabolism using 1,2 cyclohexanedione-modified low density lipoprotein. J Lipid Res 1982; 23:92-6. [PMID: 6276483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The utility of 1,2 cyclohexanedione-modified low density lipoprotein (CHD-LDL) as a marker for the measurement of receptor independent LDL catabolism has been assessed by examining its metabolic properties in cultured human fibroblasts and in rabbits. Cell culture studies showed that the inhibition of high affinity membrane receptor binding produced by the modification could be partially reversed by prolonged incubation of the CHD-LDL at 37 degrees C. Pre-exposure of the complex to alkaline pH (pH 10.5) prevented this and yielded a product that was apparently stable. Despite its regained ability to bind to the fibroblast receptor, 125I-labeled CHD-LDL incubated at 37 degrees C for 24 hr either in vivo or in vitro was removed from rabbit plasma in the same manner as freshly prepared 131I-labeled CHD-LDL and as 131I-labeled CHD-LDL that had been treated at pH 10.5. However, its plasma clearance was significantly faster than that of reductively methylated LDL. We believe that this may result from differential catabolism of these modified lipoproteins rather than from susceptibility of the CHD-LDL to receptor-directed catabolism.
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630
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Pinkerton AM, Hall JD, Shepherd J. Scanning electron microscopy of post-ejaculatory spermiogenesis in the tick Ornithodoros moubata. Tissue Cell 1982; 14:785-97. [PMID: 7170714 DOI: 10.1016/0040-8166(82)90066-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The final stages of spermiogenesis in ticks occur in the female genital tract. Scanning electron microscopy was used to follow the morphologic changes that occur in the sperm during this post-ejaculatory spermiogenesis in the African soft tick, Ornithodoros moubata, and to determine a time sequence for its occurrence in vivo. Characteristic features of the maturing and mature cell described include (1) differentiation and detachment of the operculum, (2) changes in cell shape corresponding to different developmental stages, (3) passive migration of the nucleus and acrosome from an anterior to a posterior position, and (4) eversion of that portion of the acrosomal canal containing the nucleus and acrosome. A possible fate for the remainder of the acrosomal canal is suggested by extrusion and detachment of spherical structures, the 'posterior bubbles', from the posterior end of the mature supermatozoon. A mechanism for cellular elongation resulting from contractions of the outer sheath is proposed.
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631
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Slater HR, Packard CJ, Shepherd J. Measurement of receptor-independent lipoprotein catabolism using 1,2 cyclohexanedione-modified low density lipoprotein. J Lipid Res 1982. [DOI: 10.1016/s0022-2275(20)38177-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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632
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Myher JJ, Kuksis A, Shepherd J, Packard CJ, Morrisett JD, Taunton OD, Gotto AM. Effect of saturated and unsaturated fat diets on molecular species of phosphatidylcholine and sphingomyelin of human plasma lipoproteins. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 666:110-9. [PMID: 7295758 DOI: 10.1016/0005-2760(81)90096-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Four healthy 21-23-year-old males with normal lipoprotein patterns and plasma lipid concentrations were subjected voluntarily to two diets of 5 weeks duration each: I, highly saturated fat diet; II, highly polyunsaturated fat diet. The VLDL, LDL and HDL3 fractions were isolated by conventional ultracentrifugation from each subject on the high fat diets and the molecular species of the component phosphatidylcholines and sphingomyelins were identified and quantitated by GC-MS of the t-butyldimethylsilyl ethers of the corresponding diacylglycerols and ceramides. It was shown that the diet markedly and rather evenly affected the molecular species of the phosphatidylcholines of all lipoprotein classes. However, the changes in the corresponding major molecular species were reciprocal in nature and were consistent with a demonstrated relative resistance to alterations in surface fluidity. In contrast, the dietary fat had only a minor effect on the composition of the sphingomyelins, and did not alter the characteristic differential distribution of the molecular species among the low and high density lipoprotein classes. These results, which were free of the uncertainties introduced by analyses of derived fatty acid and which were obtained on samples isolated from the same subjects, clearly demonstrate that a complete equilibration of the molecular species of the phospholipids is not attained amont the plasma lipoprotein classes even in the fasting state. The possible physico-chemical and metabolic basis of these observations is briefly discussed.
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633
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Mackie A, Caslake MJ, Packard CJ, Shepherd J. Concentration and distribution of human plasma apolipoprotein E. Clin Chim Acta 1981; 116:35-45. [PMID: 7318173 DOI: 10.1016/0009-8981(81)90166-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
(1) A sensitive, specific radioimmunoassay for human apolipoprotein E is described. (2) The method gave a plasma apolipoprotein E concentration of 0.107 +/- 0.051 g/l n = 55) in normal subjects. This value increased significantly (to 0.179 +/- 0.088 g/l) in type II hyperlipoproteinaemia (n = 31, p less than 0.01). Type III subjects formed a distinct group whose mean plasma apolipoprotein E concentration was increased four fold over normal (p less than 0.001). The level in type IV subjects (0.136 +/- 0.056, n = 30) did not differ significantly from the normal value. (3) When plasma was subjected to gel filtration on columns of 6% agarose, apolipoprotein E was located in three regions. Peak I corresponded to very low density lipoproteins, Peak II to the area between very low density and low density lipoproteins and Peak III to the leading edge of the high density lipoprotein fraction. No E protein eluted from the column after high density lipoproteins. (4) In contrast, ultracentrifugation of plasma resulted in up to 40% of apolipoprotein E appearing in the lipoprotein-free (d greater than 1.21 kg/l) fraction. This protein appears to hae been stripped largely from high density lipoprotein during ultracentrifugation. (5) Compositional analysis of very low density, intermediate density and low density lipoproteins isolated by a cumulative flotation procedure showed that the apoE/apoB ratio was the same in the first two species but fell to a very low value in low density lipoproteins.
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634
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Abstract
Balloon distension of the distal colon in diverticular disease does not produce the pressure change in response to increasing volumes that occurs in normal subjects. This phenomenon, though modified at first by resection, is not abolished by resection nor by myotomy or bran. This adaptive quality of the wall of the colon to balloon distension possibly reflects a structural change in its wall, as the phenomenon was present in the colon in diverticular disease in vitro as well as in vivo.
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635
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636
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Slater HR, Packard CJ, Bicker S, Shepherd J. Effects of cholestyramine on receptor-mediated plasma clearance and tissue uptake of human low density lipoproteins in the rabbit. J Biol Chem 1980; 255:10210-3. [PMID: 6253466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
This study examines the effects of cholestyramine (2 g/day) on the plasma clearance and tissue uptake of human low density lipoprotein (LDL) in rabbits. 1,2-Cyclohexanedione modification of human LDL abolishes its recognition by high affinity cell membrane receptors in vitro and delays its plasma clearance in comparison to native LDL. Consequently, the difference between the fractional rates of catabolism of simultaneously injected native and cyclohexanedione-treated LDL is an index of in vivo receptor-mediated clearance of the lipoprotein. When human 125I-LDL and 131I-cyclohexanedione-treated LDL were injected into rabbits, 44% of the lipoprotein was cleared from the plasma by the receptor mechanism. Various tissues were removed from the animals at the end of the turnover study and their relative uptakes of 125I native and 131I-cyclohexanedione-treated LDL were measured. All exhibited receptor activity to some extent, incorporating more native than cyclohexanedione-modified LDL. The greatest receptor activity per g of tissue was found in lymph nodes, spleen, and liver and, in terms of whole organ uptake, the liver played a major role in LDL catabolism. Treatment of the rabbits with cholestyramine lowered the circulating LDL cholesterol level by promoting its clearance (120%, p < 0.001) via the receptor pathway. This was associated with a virtual doubling of receptor-mediated incorporation of the lipoprotein into the liver. These results suggest that the drain which cholestyramine induces in the hepatic cholesterol pool promotes LDL receptor activity in this organ and thereby lowers the level of circulating LDL.
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637
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Shepherd J, Stewart JM, Clark JG, Carr K. Sequential changes in plasma lipoproteins and body fat composition during polyunsaturated fat feeding in man. Br J Nutr 1980; 44:265-71. [PMID: 7437411 DOI: 10.1079/bjn19800040] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
1. The early effects of a moderate polyunsaturated fat diet on the composition of circulating lipoproteins and adipose tissue fatty acids were measured in five healthy adults. 2. The fatty acid content and gross composition of the three major plasma lipoprotein fractions altered within 7 d of treatment. The response of depot fat was slower but did show a significant and progressive change after 14 d on the diet. 3. The efficiency of the moderate diet in changing the composition of the lipoproteins suggests that it should be equally effective in altering their metabolic handling.
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638
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639
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Shepherd J. Separation of plasma lipoproteins in the preparative ultracentrifuge. Biochem Soc Trans 1980; 8:516-8. [PMID: 7450197 DOI: 10.1042/bst0080516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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640
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Hoyos MD, Yeo JE, Renwick S, Gale DA, Dos Santos WA, Gibling JD, Hoare CE, Wilson R, Shepherd J, Webster RG, DaSilva PA. Morbidity in general practice in Barbados. W INDIAN MED J 1980; 29:97-109. [PMID: 7405197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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641
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Gianturco SH, Packard CJ, Shepherd J, Smith LC, Catapano AL, Sybers HD, Gotto AM. Abnormal suppression of 3-hydroxy-3-methylglutaryl-CoA reductase activity in cultured human fibroblasts by hypertriglyceridemic very low density lipoprotein subclasses. Lipids 1980; 15:456-63. [PMID: 7401943 DOI: 10.1007/bf02534072] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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642
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Shepherd J, Packard CJ, Bicker S, Lawrie TD, Morgan HG. Cholestyramine promotes receptor-mediated low-density-lipoprotein catabolism. N Engl J Med 1980; 302:1219-22. [PMID: 7366673 DOI: 10.1056/nejm198005293022202] [Citation(s) in RCA: 294] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We studied the influence of cholestyramine (24 g per day) on receptor-mediated and receptor-independent low-density-lipoprotein catabolism in five women with heterozygous familial hypercholesterolemia. Cholestyramine lowered the level of circulating low-density-lipoprotein apoprotein by doubling (P less than 0.01) its fractional clearance via the receptor path, but fractional catabolism by the receptor-independent route remained unchanged. Moreover, although the absolute rate of catabolism of the apoprotein was not affected by treatment, the amounts handled by each pathway altered. Catabolism via the physiologically controllable receptor route increased by 71 per cent (P less than 0.05), but there was a 12 per cent drop in clearance by the nonreceptor pathway. These data demonstrate the utility of cholestyramine in promoting low-density-lipoprotein catabolism via its specific physiologic clearance pathway. They also show that heterozygotes with familial hypercholesterolemia can increase the activity of their low-density-lipoprotein receptors when presented with an appropriate stimulus.
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643
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Shepherd J. Nutrition in the history of Tasmania. JPEN J Parenter Enteral Nutr 1980. [DOI: 10.1177/0148607180004003312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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644
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Packard CJ, Stewart JM, Third JL, Morgan HG, Lawrie TD, Shepherd J. Effects of nicotinic acid therapy on high-density lipoprotein metabolism in type II and type IV hyperlipoproteinaemia. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 618:53-62. [PMID: 6990991 DOI: 10.1016/0005-2760(80)90053-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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645
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Shapiro D, Ballantyne FC, Shepherd J. Comparison of immunonephelometry and electroimmunoassay for estimation of plasma apolipoprotein A-I. Clin Chim Acta 1980; 103:7-13. [PMID: 7389118 DOI: 10.1016/0009-8981(80)90224-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Immunonephelometry using a helium-neon laser as light-sources has been compared with the established technique of electroimmunoassay for estimation of plasma apolipoprotein A-I (apoA-I), the major protein component of high density lipoproteins (HDL). The within-batch coefficient of variation for immunonephelometry was 6.7% and for electroimmunoassay was 4.7%, but both methods showed similar between-batch precisions (6.9% and 7.0% respectively). Plasma from 122 subjects (62 male, 60 female) were analysed by both methods. Results showed good correlation but immunonephelometry gave consistently lower apoA-I values (mean +/- 1 S.D. = 1.32 +/- 0.25 g/l) than did electroimmunoassay (1.56 +/- 0.33 g/l). Plasma apoA-I concentrations obtained by both procedures were significantly higher (P less than 0.002) in females than in males. Both assays gave results which were highly correlated with high density lipoprotein cholesterol. Immunonephelometry is therefore considered to be satisfactory for estimation of plasma apoA-I concentration.
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646
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Packard CJ, Shepherd J, Joerns S, Gotto AM, Taunton OD. Apolipoprotein B metabolism in normal, type IV and type V hyperlipoproteinemic subjects. Metabolism 1980; 29:213-22. [PMID: 7374435 DOI: 10.1016/0026-0495(80)90062-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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647
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Shepherd J, Packard CJ, Stewart JM, Vallance BD, Lawrie TD, Morgan HG. The relationship between the cholesterol content and subfraction distribution of plasma high-density lipoproteins. Clin Chim Acta 1980; 101:57-62. [PMID: 7357738 DOI: 10.1016/0009-8981(80)90055-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
High density lipoprotein subfractions (HDL2 and HDL3) were separated from the plasma of 25 healthy volunteers (13 males, 12 females) rate zonal ultracentrifugation. The rotor elution profile, measured at 280 nm, was used with the specific extinction coefficient for each subfraction (HDL2, 0.60 +/- 0.11 mg protein/A280nm, HDL3, 0.86 +/- 0.10 mg protein/A280nm (n=25) to calculate their plasma concentration. Their protein and lipid composition were also determined by chemical analysis. Plasma lipids, lipoprotein cholesterol, apolipoprotein A-I, apolipoprotein A-II and apolipoprotein B levels were measured in the same subjects and correlated with the HDL subfraction concentrations. HDL cholesterol and apolipoprotein A-I concentrations correlated significantly (p less than 0.01 and 0.02 respectively) with plasma HDL2, but not with HDL3. Indeed, the significantly higher levels of HDL cholesterol and apolipoprotein A-I in the female group could be attributed entirely to an increase in circulating HDL2. This data supports the proposal that the latter subfraction is the major contributor to the anti-atherogenic role of plasma HDL.
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648
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Shepherd J. Points: Women and general practice. West J Med 1980. [DOI: 10.1136/bmj.280.6209.257-g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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649
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Shepherd J, Packard CJ, Grundy SM, Yeshurun D, Gotto AM, Taunton OD. Effects of saturated and polyunsaturated fat diets on the chemical composition and metabolism of low density lipoproteins in man. J Lipid Res 1980; 21:91-9. [PMID: 7354257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
This study examined the effects of dietary saturated and polyunsaturated fat on the chemical composition and metabolism of low density lipoproteins (LDL) in eight normal male subjects. The influence of these diets on fecal sterol excretion was also measured in four of the subjects. When compared with the saturated fat diet, the polyunsaturated diet lowered both plasma cholesterol polyunsaturated diet lowered both plasma cholesterol (23%, P less than 0.001) and triglyceride (14%, P less than 0.001) levels. Sixty-seven percent of the reduction in the former lipid resulted from a fall in LDL cholesterol (23%, P less than 0.001), although very low density (VLDL) and high density lipoprotein (HDL) cholesterol levels also fell (by 27% and 20% of their respective control value). These changes were accompanied by significant alterations in LDL composition. Specifically, during polyunsaturated fat feeding, the relative percentage cholesterol in the LDL fraction fell while that of phospholipid rose. There was no change in the percentage protein or triglyceride. The fatty acid components of LDL triglyceride, cholesteryl esters, and phospholipid were also affected by dietary fat saturation level. Overall, polyunsaturated fat feeding produced an enrichment in linoleate with reciprocal changes in palmitate, stearate, and oleate which affected triglycerides more than cholesteryl esters and phospholipids. The above changes in LDL composition were associated with alterations in the metabolism of LDL apoprotein (apoLDL). The polyunsaturated deit lowered plasma apoLDL by 13% (P less than 0.05). This resulted from an increase in the fractional catabolic rate of LDL (whether determined by plasma decay curve analysis (P less than 0.05) or urine/plasma radioactivity ratios (P less than 0.001) without significant alteration of its corporeal distribution or synthetic rate. The polyunsaturated fat diet did not cause a consistent change in fecal neutral or acidic steroid excretion. We conclude that the hypocholesterolemic action of polyunsaturated fat diets is effected by multiple mechanisms whose expression may vary from patient to patient.
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650
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Shepherd J, Packard CJ, Grundy SM, Yeshurun D, Gotto AM, Taunton OD. Effects of saturated and polyunsaturated fat diets on the chemical composition and metabolism of low density lipoproteins in man. J Lipid Res 1980. [DOI: 10.1016/s0022-2275(20)39842-4] [Citation(s) in RCA: 151] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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