Investigation of faecal volatile organic metabolites as novel diagnostic biomarkers in inflammatory bowel disease

BACKGROUND

The aetiology of inflammatory bowel disease (IBD) remains poorly understood. Recent evidence suggests an important role of gut microbial dysbiosis in IBD, and this may be associated with changes in faecal volatile organic metabolites (VOMs).

AIM

To describe the changes in the faecal VOMs of patients with IBD and establish their diagnostic potential as non-invasive biomarkers.

METHODS

Faecal samples were obtained from 117 people with Crohn's disease (CD), 100 with ulcerative colitis (UC), and 109 healthy controls. Faecal VOMs were extracted using solid-phase micro-extraction and analysed by gas chromatography mass spectrometry. Data analysis was carried out using partial least squares-discriminate analysis (PLS-DA) to determine class membership based on distinct metabolomic profiles.

RESULTS

The PLS-DA model showed clear separation of active CD from inactive disease and healthy controls (P < 0.001). Heptanal, 1-octen-3-ol, 2-piperidinone and 6-methyl-2-heptanone were up-regulated in the active CD group [variable important in projection (VIP) score 2.8, 2.7, 2.6 and 2.4, respectively], while methanethiol, 3-methyl-phenol, short-chain fatty acids and ester derivatives were found to be less abundant (VIP score of 3.5, 2.6, 1.5 and 1.2, respectively). The PLS-DA model also separated patients with small bowel CD from healthy controls and those with colonic CD from UC (P < 0.001). In contrast, less distinct separation was observed between active UC, inactive UC and healthy controls.

CONCLUSIONS

Analysis of faecal volatile organic metabolites can provide an understanding of gut metabolomic changes in IBD. It has the potential to provide a non-invasive means of diagnosing IBD, and can differentiate between UC and CD.

Characterization of Monodisperse Aqueous Latex Dispersions Prepared with N-Isopropylacrylamide

Poly-N-isopropylacrylamide (poly-NIPAM) is a water soluble nonionic polymer that exhibits a lower consolute solution temperature (LCST) of about 31°C. This paper describes the preparation and characterization of a monodisperse, hydrophilic polymer latex of poly-NIPAM, crosslinked by N,N'-methylenebisacrylamide. The presence of these crosslinking moieties will prevent dissolution of the particles at low temperatures; rather the particles will be swollen with solvent such that a microgel is formed. The swelling and rheological behaviour of the latex has been studied. The results show that at high temperatures the particles are ˜ 30 nm whilst at 25°C, the particles were ˜ 130 nm in diameter. This four fold increase in the particle diameter correspond to a ˜ sixty fold increase in volume. The rheological properties, both continuous and oscillatory shear, of these systems have also been studied and is strongly temperature dependant, reflecting the changes in phase volume of the NIPAM latex.

Renal medullary carcinoma: sonographic, computed tomography, magnetic resonance and angiographic findings

Renal medullary carcinoma is a recently described, highly aggressive tumour, occurring predominantly in young patients of African descent with sickle cell trait (SCT). All have been metastatic at surgery. Surgery, radiotherapy and chemotherapy do not appear to alter the course of the disease. The survival time is very short. Presentation is usually with haematuria, abdominal pain and weight loss. Forty-nine patients have been reported from the USA, of these 47 were African/Americans. The reports have mostly appeared in pathology journals. On review of the imaging findings reported in the radiological journals, it becomes apparent that it is possible for a radiologist to suggest a specific diagnosis in the appropriate demographic and clinical setting. Here the first British patient of Afro-Caribbean decent in whom a pre-operative diagnosis was suggested on the imaging findings of a centrally located renal pelvic tumour, encasing the pelvis on a background of SCT in a 28-year-old is described. It is expected that a high index of suspicion in the appropriate clinical setting may lead to earlier diagnosis, treatment and survival of patients. The patient is alive and reasonably well 9 months after surgery. The full range of imaging findings in renal medullary carcinoma are described.