Brian G. Keevil

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BACKGROUND & AIMS Evidence suggests that postprandial platelet-depleted plasma 5-hydroxytryptamine (5-HT) concentrations may be abnormal in irritable bowel syndrome (IBS). However, interpretation of the data has been hampered by the variable methodology and rather small numbers used in previous studies. Therefore, the aim of this study was to measure(More)
OBJECTIVE Health and lifestyle factors are associated with variations in serum testosterone levels in ageing men. However, it remains unclear how age-related changes in testosterone may be attenuated by lifestyle modifications. The objective was to investigate the longitudinal relationships between changes in health and lifestyle factors with changes in(More)
CONTEXT Mean insulin resistance (IR) is greater and it is also more variable in overweight women with polycystic ovarian syndrome (PCOS) compared to weight matched controls. Whilst treatment will reduce the mean IR, it is not known if the IR variability is also reduced. OBJECTIVE To compare the change in IR and its variability before and after treatment(More)
OBJECTIVE RIA-based sex hormone measurements offer only limited precision and specificity in the low concentration range of women. Therefore, we aimed to establish age-specific reference ranges for serum sex hormone concentrations in women using mass spectrometry and quantile regression. METHODS AND RESULTS Data from 985 women aged 20-80 yr, recruited for(More)
CONTEXT Salivary cortisol measurement is used as a practical surrogate for serum free cortisol. However, parotid tissue harbors 11β-hydroxysteroid dehydrogenase (11β-HSD2) activity converting cortisol to cortisone. OBJECTIVE This study was designed to assess the impact of parotid 11β-HSD2 activity on the measurement of salivary cortisol. PATIENTS, DESIGN,(More)
Regular monitoring of tacrolimus levels is an essential component of post-transplantation follow up in children receiving this drug. We have developed a high performance liquid chromatography tandem mass spectrometry (HPLC T-MS) methodology which measures whole blood tacrolimus levels using a 10 microL sample, thus allowing the use of fingerprick blood(More)
Theophylline poisoning with a blood level of 183 mg/l in a 38-year-old man was treated with activated charcoal by mouth, but despite this the blood level of theophylline rose and there was circulatory collapse with rhabdomyolysis, acute renal failure and hyperthermia. Treatment with charcoal haemoperfusion and simultaneous haemodialysis was given, followed(More)
Women with polycystic ovary syndrome (PCOS) were found to have a higher biological variability in insulin resistance (IR) compared to controls, but it is unknown whether this variability in IR differs between PCOS who are anovulatory compared to those who have an ovulatory cycle. The primary aim of this study was to compare and contrast the variability of(More)
A simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous analysis of cyclosporin A (CsA) and creatinine using capillary blood has been developed. Venous and capillary blood samples were taken predose and at C2 from 65 heart and lung transplant recipients (65 x 4 samples). For comparisons, serum creatinine and(More)
BACKGROUND The accurate measurement of cortisol by immunoassay is compromised by the potential for cross-reactivity of reagent antibodies with structurally related steroids present in serum. This susceptibility is potentiated when normal steroid metabolism is altered pharmaceutically by antisteroidogenic drugs utilized in the management of Cushing's(More)