Short-term glucose variability in healthy volunteers is not associated with raised oxidative stress markers

It is unknown whether glycaemic variability adds to the risk of microvascular complications of diabetes over and above the mean glucose value for a patient. We examined the effect of purposefully induced short-term glycaemic variability on oxidative stress markers. Eleven healthy subjects underwent three sequential glycaemic states; sustained hyperglycaemia, sustained euglycaemia and variable glycaemia, using glycaemic clamps for 3 h. Twenty-four hours urinary 8-isoprostane-PGF2α was measured before and after each glycaemic state to assess oxidative stress. The median and interquartile range of the urinary 8-iso-PGF2α in ng/24 h were (1373, 513), (996, 298) and (1227, 472) for the euglycaemic, hyperglycaemic and variable states, respectively. There was no significant difference in urinary isoprostanes between the three different states; mean ranks 20.9, 11.9 and 18.2 for the euglycaemic state, hyperglycaemic state and glycaemic variability state, respectively, p = 0.083. In conclusion, we did not see a significant increase in the urinary isoprostanes when glycaemic variability was induced under controlled conditions in healthy individuals.

A comparison of methods for the measurement of 8-isoPGF(2α): a marker of oxidative stress

BACKGROUND

Oxidative stress describes the cellular damage caused by excess reactive oxygen species not adequately inactivated by antioxidants. Oxidative stress has been implicated in playing a role in many disorders. Lipid peroxidation end-products are employed as markers of oxidative stress, of which the isoprostane, 8-iso-PGF(2α), is widely used. 8-iso-PGF(2α) is measured in plasma or urine by gas chromatography-mass spectrometry (GC/MS), liquid chromatography-mass spectrometry (LC/MS), tandem-mass spectrometry or enzyme-linked immunosorbent assay (ELISA). However, discrepancies between the specificity of these methods means correlation is poor.

METHODS

A tandem-mass spectrometric (LC/MS/MS) method, using immunoaffinity purification, for urinary 8-iso-PGF(2α) was developed and compared with two commercial ELISAs (A--Cayman Chemicals, B--Oxford Biomedical Research) in urine samples (n = 156).

RESULTS

An LC/MS/MS method coupled to immunoaffinity purification was developed with satisfactory performance and comparison to ELISAs A and B. Spearman rank correlation demonstrated significant correlation between all methods (P = <0.0001); however, r² values ranged from 0.68 to 0.72. Bland-Altman plots revealed a proportional positive bias of ELISA B when compared with ELISA A and LC/MS/MS. Furthermore, the agreement between ELISA A and LC/MS/MS was poor.

CONCLUSIONS

The poor agreement between methods for measurement of 8-iso-PGF(2α) highlights differences in selectivity. 8-iso-PGF(2α) is an isoprostane, a family of isomeric end-products of arachidonic acid peroxidation, which are produced by peroxidation or enzymatically. This makes avoiding cross-reactivity between 8-iso-PGF(2α) and related isomers challenging. When assessing oxidative stress studies, the selectivity of the methods used should be taken into account, particularly when comparing studies.

Common psychiatric disorders over a lifetime: age of onset, risk and treatment contact in the Nigerian survey of mental health and wellbeing

The study is to estimate prevalence, risk, and contact with services of mental health problems in the Nigerian community. Face-to-face interviews with a representative sample of persons aged 18 years and over (n = 6752) using the World Health Organization's Composite International Diagnostic Interview, Version 3. Lifetime DSM-IV prevalence estimates were 6.5% for anxiety disorders, 3.3% for mood disorders, 3.7% for substance use disorders, and 12.0% for any disorder. The median age of onset (represented by the 50th percentile age of onset) is 25 years for any disorder but ranged from 11 years for anxiety disorder to 42 years for mood disorder. The projected lifetime risks at age 75 years were considerably higher than prevalence estimates. For mood disorders, lifetime risk was 170% higher than the prevalence estimate. Ascertainment bottlenecks seem to account for some low prevalence estimates. In general, only a minority of persons with mental disorders made any treatment contact. The median delay in duration before seeking care ranged between 6 years for mood disorders and 16 years for anxiety disorders. Projected lifetime risks of mood disorders and possible false negatives for some disorders suggest that the societal burden of mental disorders is considerably higher than the prevalence estimates indicate. Nevertheless, even for identified cases, current treatment coverage falls far short of need.