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Plasma, platelet and red blood cell long chain fatty acids in non-insulin-dependent diabetes mellitus

Ling, Kam Lun Eddie; (1994) Plasma, platelet and red blood cell long chain fatty acids in non-insulin-dependent diabetes mellitus. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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The development of large vessel disease (LVD) in non-insulin-dependent diabetic mellitus (NIDDM) may partly be due to the combined effects of dyslipidaemia and altered plasma, platelet and red blood cell fatty acid compositions. These factors could act in a synergistic manner, leading to the increased morbidity and mortality seen in NIDDM. Populations consuming large quantities of (n-3) and monounsaturated fatty acids (MFA) have relatively low incidence of LVD. This phenomenon has been attributed to the beneficial effects of these fatty acids on lipid metabolism, platelet functions and other mechanisms connected to atherogenesis. However, there are relatively little information available on the compositions of plasma lipids and lipoproteins, or plasma, platelet and red blood cell fatty acids in male NIDDM patients with and without LVD, and on the therapeutic values of (n-3) fatty acids and MFA in NIDDM patients without LVD. Thus, this study was designed to study the differences in plasma lipid and lipoprotein compositions and fatty acid profiles (plasma, platelet and red blood cell) between NIDDM patients (20 males with LVD, 20 males without LVD) and normal subjects (n=20). The effects of dietary (n-3) fatty acid (fish oil, n=10) and MFA (olive oil, n=10) supplementations on the lipid and fatty acid profiles in NIDDM patients without LVD were also evaluated. NIDDM patients, particularly those with LVD, had raised plasma triacylglycerol levels and the excesses may be accommodated in the large VLDL. Although individual lipoprotein cholesterol concentrations were similar in all diabetics, patients with LVD had higher plasma cholesterol levels. This difference may due to the concomitant increased plasma 18:1(n-9) and decreased plasma 18:2(n-6) levels, bringing about an increase in cholesterol synthesis. Plasma and red blood cell 20:5(n-3) levels were higher in NIDDM patients, whereas their platelets and red blood cells 20:4(n-6) levels were lower. In addition, the platelet saturated fatty acid (SFA) contents were higher. The unexpected plasma and red blood cell 20:5(n-3) levels seen in the diabetics may due to the re-direction of the Δ5 desaturase activity towards the precursor of 20:5(n-3), whereas, higher platelet SFA levels may have undesirable effects on platelet aggregation. Higher SFA and lower 18:2(n-6) levels were also seen in the red blood cells in NIDDM patients with LVD, reflecting impaired fatty acid acylation with lipids. NIDDM patients (without LVD) on fish oil increased their plasma HDL2 levels without concomitant changes in VLDL levels, possibly due to the formation of medium-sized VLDL particles, acting as an extra substrate for HDL2 formation. Increases in plasma, platelet and red blood cell 20:5(n-3) contents and less markedly 22:6(n-3) were also seen in diabetics on fish oil. These changes occurred at the expense of (n-6) fatty acids. In contrast, olive oil had no effects on plasma, platelet and red blood cell fatty acid compositions. Both oils had produce a slight worsening of glycaemia in diabetics and therefore, should be used with caution as a treatment of dyslipidaemia in NIDDM.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Plasma, platelet and red blood cell long chain fatty acids in non-insulin-dependent diabetes mellitus
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Health and environmental sciences; Fatty acids; Plasma; Platelets
URI: https://discovery.ucl.ac.uk/id/eprint/10102441
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