First observation of a potential non-invasive breath gas biomarker for kidney function.

We report on the search for low molecular weight molecules-possibly accumulated in the bloodstream and body-in the exhaled breath of uremic patients with kidney malfunction. We performed non-invasive analysis of the breath gas of 96 patients shortly before and several times after kidney transplantation using proton-transfer-reaction mass spectrometry (PTR-MS), a very sensitive technique for detecting trace amounts of volatile organic compounds. A total of 642 individual breath analyses which included at least 41 different chemical components were carried out. Correlation analysis revealed one particular breath component with a molecular mass of 114 u (unified atomic mass units) that clearly correlated with blood serum creatinine, which is the currently accepted marker for assessing the function of the kidney. In particular, daily urine production showed good correlation with the identified breath marker. An independent set of seven samples taken from three patients at the onset of dialysis and three controls with normal kidney function confirmed a significant difference in concentration between patients and controls for a compound with a molecular mass of 114.1035 u using high mass resolving proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). A chemical composition of C7H14O was derived for the respective component. Fragmentation experiments on the same samples using proton-transfer-reaction triple-quadrupole tandem mass spectrometry (PTR-QqQ-MS) suggested that this breath marker is a C7-ketone or a branched C7-aldehyde. Non-invasive real-time monitoring of the kidney function via this breath marker could be a possible future procedure in the clinical setting.

Long-term results and complications following adjustable gastric banding.

This study was performed to assess our long-term results with laparoscopic gastric banding in patients with an observation period of at least 9 years calculated from the date of operation. Between January 1996 and December 2000, a total of 276 patients (83% female) underwent laparoscopic gastric banding at our institution. Mean preoperative body mass index (BMI) was 44 +/- 6 kg/m(2). BMI after 1, 5, 7, 9, and 10 years was 33 +/- 6, 30 +/- 6, 31 +/- 6, 32 +/- 7, and 31 +/- 7 kg/m(2), respectively. Mean excess weight loss after 1 year was 57.1 +/- 23.0% and after 5, 7, 9, and 10 years 73.2 +/- 29.6%, 65.9 +/- 29.3%, 61.8 +/- 32.8%, and 64.0 +/- 32.1%, respectively. Median completeness of follow-up was 80%. Of the study population, 146 (52.9%) patients had at least one complication requiring reoperation. Presently, only 148 (53.6%) patients still have their original band, 49 (17.8%) had their original band replaced with a new one, and 79 (28.6%) had their band removed. Thirty-three patients had no second bariatric operation, a Roux-en-Y gastric bypass was done in 39 patients, and six patients underwent sleeve gastrectomy. Our long-term results are good with regard to weight loss in those patients who still have their band in situ. This is accompanied by a high complication rate and a 29% band loss rate.