J. Vertommen

Antioxidant status and lipoprotein peroxidation in chronic fatigue syndrome

The aetiology and pathogenesis of the Chronic Fatigue Syndrome (CFS) are still largely unresolved. Accompanying metabolic disorders such as selective n-6 fatty acid depletion suggest that oxidative stress and more specifically lipid peroxidation might play a role in its pathogenesis. In order to investigate this hypothesis, oxidant-antioxidant status and its impact on lipoprotein peroxidation in vitro was examined in 61 patients with unexplained fatigue lasting more than 1 month. They were subdivided into 2 groups: group CFS+ (33 subjects) fulfilled the 1988 Center of Disease Control criteria for CFS and group CFS- did not but was similar as regards age, sex distribution and clinical characteristics. Antioxidant status was similar in the 2 groups except for lower serum transferrin in the CFS + (mean (95 % CI) 2.41 (2.28-2.54) versus 2.73 (2.54-2.92) g/L in the CFS-, p = 0.009) and higher lipoprotein peroxidation in vitro: 6630 (5949-7312) versus 5581 (4852-6310) nmol MDA/mg LDL and VLDL cholesterol x minutes, p = 0.035). CFS intensified the influence of LDL cholesterol (p = 0.012) and of transferrin (p = 0.045) on peroxidation in vitro, suggesting additional pro-oxidant effects. These results indicate that patients with CFS have increased susceptibility of LDL and VLDL to copper-induced peroxidation and that this is related both to their lower levels of serum transferrin and to other unidentified pro-oxidising effects of CFS.

Beta-cell, thyroid, gastric, adrenal and coeliac autoimmunity and HLA-DQ types in type 1 diabetes

The autoimmune attack in type 1 diabetes is not only targeted to β cells. We assessed the prevalence of thyroid peroxidase (aTPO), parietal cell (PCA), antiadrenal (AAA) and endomysial antibodies (EmA‐IgA), and of overt autoimmune disease in type 1 diabetes, in relation to gender, age, duration of disease, age at onset, β‐cell antibody status (ICA, GADA, IA2A) and HLA‐DQ type. Sera from 399 type 1 diabetic patients (M/F: 188/211; mean age: 26 ± 16 years; duration: 9 ± 8 years) were tested for ICA, PCA, AAA and EmA‐IgA by indirect immunofluorescence, and for IA2A (tyrosine phosphatase antibodies), GADA (glutamic acid decarboxylase‐65 antibodies) and aTPO by radiobinding assays. The prevalence rates were: GADA 70%; IA2A, 44%; ICA, 39%; aTPO, 22%; PCA, 18%; EmA‐IgA, 2%; and AAA, 1%. aTPO status was determined by female gender (β = − 1·15, P = 0·002), age (β = 0·02, P = 0·01) and GADA + (β = 1·06, P = 0·02), but not by HLA‐DQ type or IA2A status. Dysthyroidism (P < 0·0001) was more frequent in aTPO + subjects. PCA status was determined by age (β = 0·03, P = 0·002). We also observed an association between PCA + and GADA + (OR = 1·9, P = 0·049), aTPO + (OR = 1·9, P = 0·04) and HLA DQA1*0501‐DQB1*0301 status (OR = 2·4, P = 0·045). Iron deficiency anaemia (OR = 3·0, P = 0·003) and pernicious anaemia (OR = 40, P < 0·0001) were more frequent in PCA + subjects. EmA‐IgA + was linked to HLA DQA1*0501‐DQB1*0201 + (OR = 7·5, P = 0·039), and coeliac disease was found in three patients. No patient had Addisons disease. In conclusion, GADA but not IA2A indicate the presence of thyrogastric autoimmunity in type 1 diabetes. aTPO have a female preponderance, PCA are weakly associated with HLA DQA1*0501‐DQB1*0301 and EmA‐IgA + with HLA DQA1*0501‐DQB1*0201.

Oxidative stress status in patients with diabetes mellitus: relationship to diet

Objective: To investigate the relationship between dietary intakes and in vivo oxidative stress (OS) status in diabetic patients.Design: Case–control study.Setting: Outpatient-Clinic and Laboratory Endocrinology, University Antwerp.Subjects and methods: A total of 30 patients (24 type 1 diabetes mellitus (T1DM)/6 type 2 diabetes mellitus (T2DM) were asked to complete a 2 weekdays+1weekend day food consumption questionnaire during the week preceding their yearly diabetes control consultation, when samples were collected for the assay of oxidative stress (OS) (blood levels of antioxidants, peroxides, malondialdehyde (MDA) and minerals). Blood samples were also collected from 25 age- and sex-matched healthy controls.Results: Diabetic patients had lower glutathione (5.80±1.15 vs 6.75±1.03 μmol/g Hb in the controls, P=0.002) and higher MDA (0.687±0.212 vs 0.545±0.101 μmol/l, P=0.002). Although the group average intakes were within the Belgian RDA, intakes of fat >35% energy, fibre <15 g/1000 kcal, fruit <2 portions and vitamin E <10 mg/day were seen in more than 20 patients. Blood antioxidants did not correlate with intakes of energy, fat, protein or fibres or of their respective antioxidant. Vitamins A and E correlated with serum lipids (r=0.58, P <0.0005 between serum α-tocopherol and cholesterol). Blood peroxide levels were only related to intakes of saturated fat and cholesterol (P<0.05). In diabetic subjects but not in controls (P<0.05) MDA was related to glutathione and uric acid.Conclusions: In diabetic patients, blood levels of antioxidants are not related to their dietary intakes but to serum lipids. Levels of oxidative damage products are only related to intakes of saturated fats and cholesterol and to levels of endogenous antioxidants.

A rapid and simple method for measuring the susceptibility of low-density-lipoprotein and very-low-density-lipoprotein to copper-catalyzed oxidation.

Much evidence has accumulated to suggest a role for the oxidation of low-density-lipoprotein (LDL) and very low-density-lipoprotein (VLDL) in the pathogenesis of atherosclerosis. The susceptibility of lipoprotein to copper-catalyzed oxidation is often used to evaluate its oxidizability. A method was developed which isolates the non-high-density lipoprotein (non-HDL) fraction and removes EDTA by a dextran-magnesium precipitation method. The oxidizability of this fraction is evaluated by monitoring the fluorescence and measuring thiobarbituric acid reactive substances (TBARS) at different intervals of incubation. Those parameters reflect apolipoprotein B (apo B) modification and lipid degradation during LDL and VLDL oxidation. Our assay is sensitive enough to study factors which can influence the oxidizability of LDL and VLDL. The method is simple, rapid and can be easily conducted in a routine laboratory.

Effects of pravastatin on lipid levels, in vitro oxidizability of non-HDL lipoproteins and microalbuminuria in IDDM patients

The effects of pravastatin on plasma lipid levels, in vitro oxidizability of the non-HDL fraction, metabolic control, urinary albumin excretion, and four serum enzymes (SGPT, SGOT, GT and CPK) were studied in 20 insulin-dependent diabetic patients (IDDM) with incipient nephropathy. The patients were divided into two groups and the study was carried out by a crossover design. After 12 weeks pravastatin treatment (20 mg daily), plasma cholesterol, LDL-cholesterol and apolipoprotein B (Apo B) decreased by 22, 19 and 15%, respectively. The thiobarbituric acid reactive substances (TBARS) formation and the oxidation lagtime of the non-HDL fraction during the in vitro incubation with copper were not changed before and after treatment. The HbA1c and blood glucose levels, urinary albumin excretion, SGOT, SGPT and GT were not influenced by pravastatin treatment. CPK activity was elevated after 12 weeks of pravastatin treatment, and this elevation persisted even after the 12 weeks placebo period. So, pravastatin could be used as an effective drug for IDDM patients with incipient nephropathy, but close monitoring of the CPK activity is recommended.

Minimally-Invasive and Non-Invasive Continuous Glucose Monitoring Systems: Indications, Advantages, Limitations and Clinical Aspects

Accurate and reliable devices sensing glucose on a (near)-continuous basis may facilitate specific therapeutic adjustments that need to be made to avoid hypo- and hyperglycaemic excursions, thereby improving metabolic control. Current continuous glucose monitoring (CGM) systems indicate the glucose level, the direction and magnitude of change of glucose levels, and can be used to assess glycaemic variability. In addition, real-time CGM sensors can serve as a tool to predict impending glucose excursions, thereby providing alarm signals of hypo- and hyperglycaemic values warning the patient to take preventative actions. Quality of life may also improve by using CGM via reducing the fear of hypoglycaemia. Particularly patients with brittle diabetes, hypoglycaemia unawareness, gastroparesis, pregnant women, or pump users, who are motivated to participate in their diabetes care and are technologically adept, may benefit from CGM. However, to successfully implement CGM in daily practice, these devices must be accurate and reliable, and one must be aware of the limitations of current CGM systems, that originate from physiological and technical aspects. Whether CGM succeeds in improving metabolic control, reducing hypoglycaemic episodes, and improving quality of life in the majority of patients remains to be proven. Should this be the case, real-time CGM may reduce chronic diabetic complications, and avoid hospitalisations, thereby reducing health care costs. In this article we will review indications, advantages, limitations, clinical and technical aspects of current minimally-invasive and non-invasive CGM sensors.

In New‐onset Insulin‐dependent Diabetic Patients the Presence of Anti‐thyroid Peroxidase Antibodies is Associated with Islet Cell Autoimmunity and the High Risk Haplotype HLA DQA1*0301‐DQB1*0302

In 157 new onset IDDM (104 men, 53 women, ages 10–39 yr) anti‐thyroid peroxidase anti‐bodies (anti‐TPO) were assayed with a specific immunological test. Values greater than 100 U ml−1 were considered positive. Seventeen per cent of the patients were positive (32% of the women versus 10% of the men, p < 0.001). Eighty‐five per cent of the anti‐TPO + patients have a positive titre of islet‐cell antibodies (ICA ⩾ 12 JDFU) versus 64% of the anti‐TPO−patients (p < 0.05). When patients were subdivided in a young (10–25 yr) and an older age group (26–39 yr) this association was also true for ICA ⩾ 50 JDFU and valid for insulin autoantibodies (IAA) at low (⩾0.7%) and high risk (⩾1.5%) (p < 0.005) in the second group. The median of the TSH concentration was not different between anti‐TPO+ and anti‐TPO− when the group is considered as a whole. In the anti‐TPO+ men (26–39 yr) TSH was however significantly greater (1.55 μU ml−1, range 0.74–8.5 versus 1.4 μU ml−1, range 0.21–3.5, p < 0.0001) when compared to the anti‐TPO‐men of the same age group. The haplotype HLA DQA1*0301‐DQB1*0302 was more frequent in the anti‐TPO+ (39%) than in the anti‐TPO− (23%) patients (p < 0.02) for the age group 26–39 yr but not for the age group 10–25 yr. The other diabetes susceptibility haplotype DQA1*0501‐DQB1*0201 was less frequent in anti‐TPO+ patients. In conclusion we suggest that thyroid auto‐immunity must be part of the initial screening of IDDM especially when patients are older at clinical onset of the disease.

Effects of intravenous supplementation with α-tocopherol in patients receiving total parenteral nutrition containing medium- and long-chain triglycerides

Objective: To compare the effects of a lipid emulsion containing medium-chain triglycerides (MCT) and supplemented with α-tocopherol to a conventional long-chain triglyceride (LCT) emulsion.Design: Randomised double blind study.Setting: Department of Internal Medicine, Antwerp University Hospital.Subjects and interventions: Twenty-four patients with an indication for total parenteral nutrition for a minimum of 10 days were randomly assigned to two groups: group E received as lipid source MCT/LCT (50/50) suplemented with 100 mg dl-α-tocopherol/day and group C received LCT. Blood samples were analysed at inclusion, after 4–6 and after 9–11 days.Results: In group E, serum α-tocopherol doubled from 11.4±6.9 at inclusion to 20.9±7.9 and to 23.8±8.8 µg/ml after 4 and 9 days, respectively, but did not change in group C (P=0.008). Production of thiobarbituric acid-reacting substances (TBARS) after 120 min incubation with copper decreased from 66±34 at inclusion to 29±25 nmol MDA/mg LDL and VLDL-cholesterol after 4 and to 42±17 after 9 days (P=0.022 when compared to group C, which underwent no significant changes). Velocity of production of fluorescent products decreased in group E but not in group C (P=0.026).Conclusions: Supplementation of TPN containing MCT/LCT with 100 mg dl-α-tocopherol/day leads to a doubling in serum α-tocopherol and to a decrease in the susceptibility of LDL and VLDL to peroxidation in vitro.Sponsorship: This study was partly financed by B Braun Medical NVSA, Diegem, Belgium.

Platelet prothrombinase activity, a final pathway platelet procoagulant activity, is overexpressed in type 1 diabetes: no relationship with mean platelet volume or background retinopathy

There is overwhelming evidence that platelets from diabetic individuals are hyperreactive, not only when mi crovascular complications are apparent, but already at an early stage of the disease. There is still controversy about the ques tion of whether primary hyperreactive platelets may contribute to the origin or progression of microangiopathy or whether diabetic platelet hyperfunctionality is just a logical conse quence of a continuous low-grade activation of platelets by contact with a diseased microvascular wall. As a consequence of platelet activation, the outer layer of its phospholipid mem brane is more procoagulant than in the quiescent state, stimu lating thrombin formation in plasma. This platelet function is called platelet procoagulant activity. We studied platelet pro thrombinase activity (PPA), a final pathway platelet procoagu lant activity of type 1 diabetic platelets, and looked for an eventual correlation with microvascular disease (background retinopathy) and mean platelet volume (MPV). Stypven clot ting times (SCTs), reflecting PPA expression, and MPV of citrated platelet-rich plasma (PRP), were measured in 21 pa tients with type 1 diabetes—10 with and 11 without back ground retinopathy—under clinically acceptable metabolic control and compared them to 20 disease-free voluntary con trols. We also compared PPA expression and MPV in diabetic individuals with and without retinopathy. With the SCT, a se lective test adapted for studying PPA in PRP, we found hyper expression of PPA in all diabetic patients. We found no differ ence in MPV between diabetic and control PRP. Comparing patients with and without background retinopathy we found no significant difference in PPA expression. From these results, we suggest that the phospholipid surface of diabetic platelets, more than the surface of normal control platelets, stimulate the expression of PPA. This diabetic platelet coagulant anomaly was not related to an increased platelet mass (higher MPV) nor to the presence of microangiopathy. We conclude that PPA hyperexpression is associated with patients with type 1 diabe tes, already occurring in an early stage of the disease, and not necessarily a consequence of early-stage microvascular disease, because the anomaly is also demonstrable, in the same degree, in patients with diabetes without microangiopathy.

Effect of Statil (ICI 128436) on Erythrocyte Viscosity In Vitro

The hypothesis that sorbitol accumulation could contribute to a reduced erythrocyte deformability in diabetes was investigated. Erythrocyte sorbitol and erythrocyte viscosity at high and low shear rates were studied in 20 insulin-dependent diabetic (IDDM) and 20 matched control subjects. An increased erythrocyte sorbitol and an increased low-shear erythrocyte viscosity were found in the IDDM patients, but there was no significant correlation (r = .11, NS) between the parameters. Incubation (3 h, 37 degrees C) in a Krebs buffer containing 33.3 mM glucose resulted in a significant sorbitol accumulation, but erythrocyte viscosity was not affected. Despite this fact, addition of 1 mM statil (ICI 128436) in the 5.5- and 33.3-mM glucose media not only prevented erythrocyte sorbitol accumulation but also improved erythrocyte viscosity in diabetic and control subjects. The effect was more pronounced at the low (∼16%) than at the high (∼2%) shear rate. The effect on erythrocyte viscosity disappeared by washing the erythrocytes after incubation, although erythrocyte sorbitol remained different. Our results suggest that sorbitol accumulation does not contribute to an increased erythrocyte viscosity in diabetes, and statil shows a positive effect on erythrocyte viscosity independent of its aldose reductase–inhibiting property.