Faisel Khan

Faisel Khan, PhD, is a Professor of Cardiovascular Sciences, School of Medicine, University of Dundee, UK, and Honorary Clinical Scientist with NHS Tayside, Dundee, UK.

Notable studies

 * 2015, High-dose intermittent vitamin D3 supplementation does not improve markers of vascular function or symptoms in patients with chronic fatigue syndrome - a randomised controlled trial
 * 2015, Effect of intermittent vitamin D3 on vascular function and symptoms in chronic fatigue syndrome – A randomised controlled trial"Abstract: 'Low 25-hydroxyvitamin D levels are common in patients with chronic fatigue syndrome; such patients also manifest impaired vascular health. We tested whether high-dose intermittent oral vitamin D therapy improved markers of vascular health and fatigue in patients with chronic fatigue syndrome. METHODS AND RESULTS: Parallel-group, double-blind, randomised placebo-controlled trial. Patients with chronic fatigue syndrome according to the Fukuda (1994) and Canadian (2003) criteria were randomised to receive 100,000 units oral vitamin D3 or matching placebo every 2 months for 6 months. The primary outcome was arterial stiffness measured using carotid-femoral pulse wave velocity at 6 months. Secondary outcomes included flow-mediated dilatation of the brachial artery, blood pressure, cholesterol, insulin resistance, markers of inflammation and oxidative stress, and the Piper Fatigue scale. As many as 50 participants were randomised; mean age 49 (SD 13) years, mean baseline pulse wave velocity 7.8 m/s (SD 2.3), mean baseline office blood pressure 128/78 (18/12) mmHg and mean baseline 25-hydroxyvitamin D level 46 (18) nmol/L. 25-hydroxyvitamin D levels increased by 22 nmol/L at 6 months in the treatment group relative to placebo. There was no effect of treatment on pulse wave velocity at 6 months (adjusted treatment effect 0.0 m/s; 95% CI -0.6 to 0.6; p = 0.93). No improvement was seen in other vascular and metabolic outcomes, or in the Piper Fatigue scale at 6 months (adjusted treatment effect 0.2 points; 95% CI -0.8 to 1.2; p = 0.73). CONCLUSION: High-dose oral vitamin D3 did not improve markers of vascular health or fatigue in patients with chronic fatigue syndrome."
 * 2014, Association between vitamin D status and markers of vascular health in patients with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME)"Abstract: 'Low circulating 25 hydroxyvitamin D (25OHD) levels have been associated with increased blood pressure, impaired vascular health and an increased risk of cardiovascular events. We have previously shown that patients with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) have vascular dysfunction, which is related to increased levels of low grade inflammation and oxidative stress. Vitamin D may affect the cardiovascular system through multiple pathways — via influence on the inflammatory process and oxidative stress, by effects on cardiac myocyte hypertrophy, vascular stiffness and calcification, and by direct effects on endothelial function.'"
 * 2012, Large and small artery endothelial dysfunction in chronic fatigue syndrome"Abstract: 'There is accumulating evidence that myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is associated with cardiovascular symptoms including autonomic dysfunction, impaired blood pressure regulation and loss of beat-to-beat heart rate control. A number of recent studies reporting raised levels of oxidative stress, low-grade inflammation and increased arterial stiffness contribute to a picture of increased cardiovascular risk in ME/CFS. One potential site of oxidative injury is the vascular endothelium, and such damage would be expected to lead to endothelial cell dysfunction and diminished vasodilator capacity.'"
 * 2010, Biochemical and Vascular Aspects of Pediatric Chronic Fatigue Syndrome (FULL TEXT)
 * 2004, Peripheral cholinergic function in humans with chronic fatigue syndrome, Gulf War syndrome and with illness following organophosphate exposure"'Abstract - In the present study, we have investigated whether the peripheral cholinergic abnormalities that we have reported previously [Spence, Khan and Belch (2000) Am. J. Med. 108, 736–739] in patients with chronic fatigue syndrome (CFS) are also present in those with Gulf War syndrome (GWS) and agricultural workers exposed to organophosphate pesticides, where cholinesterase inhibition is specifically implicated. We also looked at whether these abnormalities might be due to a reduction in the activity of cholinesterase expressed on the vascular endothelium. We used laser Doppler imaging to measure the forearm skin blood flow responses to iontophoresis of acetylcholine and of methacholine (which is resistant to breakdown by cholinesterase) in patients with CFS, GWS and those with a history of ill health after definite organophosphate exposure, as well as in matched healthy controls. The response to acetylcholine was significantly higher in patients with CFS than in controls (P=0.029, repeated-measures ANOVA), but was normal in those with GWS and those exposed to organophosphates. The methacholine response was higher than the acetylcholine response in all patient groups except for those with CFS, where there was no difference between the responses. Although there are many clinical similarities between these three illnesses, our results indicate peripheral cholinergic abnormalities in the vascular endothelium of only patients with CFS, suggesting that this syndrome has a different aetiology, which might involve inhibition of vascular cholinesterase.'"
 * 2004, Acetylcholine mediated vasodilatation in the microcirculation of patients with chronic fatigue syndrome "'Abstract - The aetiology of chronic fatigue syndrome (CFS) remains controversial and a number of hypotheses have been put forward to explain it. Research into the condition is hindered by the considerable heterogeneity seen across patients but several reports have highlighted disturbances to cholinergic mechanisms in terms of central nervous system activity, neuromuscular function and autoantibodies to muscarinic cholinergic receptors. This paper examines an altogether separate function for acetylcholine and that is its role as an important and generalized vasodilator. Most diseases are accompanied by a blunted response to acetylcholine but the opposite is true for CFS. Such sensitivity is normally associated with physical training so the finding in CFS is anomalous and may well be relevant to vascular symptoms that characterise many patients. There are several mechanisms that might lead to ACh endothelial sensitivity in CFS patients and various experiments have been designed to unravel the enigma. These are reported here."

Online presence

 * Professor Faisel Khan, Faculty bio page