Chalmers Ronald A, Jones Mark G, Goodwin C Stewart, Amjad Saira
St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK.
Clin Chim Acta. 2006 Feb;364(1-2):148-58. doi: 10.1016/j.cccn.2005.05.036. Epub 2005 Aug 10.
McGregor et al. reported increased levels of an unidentified urinary compound (CFSUM1) in patients with chronic fatigue syndrome (CFS), with reduced excretion of another unidentified compound (CFSUM2), and suggested the possibility of chemical or metabolic 'markers' for CFS. The identity of CFSUM1 as reported was erroneous and the identities of these compounds have remained unknown until now. Urine samples were obtained from 30 patients with ME/CFS, 30 age- and sex-matched healthy controls, 20 control patients with depression and 22 control patients with rheumatoid arthritis. Samples were prepared using the published methods of McGregor et al. to produce heptafluorobutyryl-isobutyl derivatives of urinary metabolites. Alternative preparations utilised isopropyl, n-butyl and trifluoroacetyl derivatives. These were separated and identified using gas chromatography-mass spectrometry. CFSUM2 was identified as being partially derivatised [isobutyl ester-mono-heptafluorobutyryl (HFB)] serine. CFSUM1 was identified as partially derivatised pyroglutamic acid, being the isobutyl ester without formation of a HFB derivative. Both CFSUM1 and CFSUM2 are artefacts of the sample preparation procedure and previously reported quantitative abnormalities of CFSUM1 and CFSUM2 in urine from patients with ME/CFS are also artefactual. Pyroglutamic acid may be of primarily dietary origin. The methods used cannot provide reliable qualitative or quantitative data on urinary metabolites. No clinical or biochemical significance can be drawn between these compounds in ME/CFS or any other clinical conditions.
麦格雷戈等人报告称，慢性疲劳综合征（CFS）患者体内一种不明尿液化合物（CFSUM1）水平升高，另一种不明化合物（CFSUM2）的排泄量减少，并提出CFS存在化学或代谢“标志物”的可能性。所报道的CFSUM1的身份是错误的，直到现在这些化合物的身份仍然未知。从30例肌痛性脑脊髓炎/慢性疲劳综合征（ME/CFS）患者、30例年龄和性别匹配的健康对照者、20例抑郁症对照患者和22例类风湿性关节炎对照患者中获取尿液样本。使用麦格雷戈等人发表的方法制备样本，以产生尿液代谢物的七氟丁酰异丁酯衍生物。替代制剂使用异丙酯、正丁酯和三氟乙酰衍生物。使用气相色谱-质谱法对这些衍生物进行分离和鉴定。CFSUM2被鉴定为部分衍生化的[异丁酯-单七氟丁酰（HFB）]丝氨酸。CFSUM1被鉴定为部分衍生化的焦谷氨酸，即未形成HFB衍生物的异丁酯。CFSUM1和CFSUM2都是样本制备过程中的人为产物，先前报道的ME/CFS患者尿液中CFSUM1和CFSUM2的定量异常也是人为造成的。焦谷氨酸可能主要来源于饮食。所使用的方法无法提供关于尿液代谢物的可靠定性或定量数据。在ME/CFS或任何其他临床情况下，这些化合物之间无法得出临床或生化意义。
