In vivo (1)H MRS and (31)P MRSI of the response to cyclocreatine in transgenic mouse liver expressing creatine kinase.

Hepatocyte transplantation has been explored as a therapeutic alternative to liver transplantation, but a means to monitor the success of the procedure is lacking. Published findings support the use of in vivo (31)P MRSI of creatine kinase (CK)-expressing hepatocytes to monitor proliferation of implanted hepatocytes. Phosphocreatine tissue level depends upon creatine (Cr) input to the CK enzyme reaction, but Cr measurement by (1)H MRS suffers from low signal-to-noise ratio (SNR). We examine the possibility of using the Cr analog cyclocreatine (CCr, a substrate for CK), which is quickly phosphorylated to phosphocyclocreatine (PCCr), as a higher SNR alternative to Cr. (1)H MRS and (31)P MRSI were employed to measure the effect of incremental supplementation of CCr upon PCCr, γ-ATP, pH and Pi /ATP in the liver of transgenic mice expressing the BB isoform of CK (CKBB) in hepatocytes. Water supplementation with 0.1% CCr led to a peak total PCCr level of 17.15 ± 1.07 mmol/kg wet weight by 6 weeks, while adding 1.0% CCr led to a stable PCCr liver level of 18.12 ± 3.91 mmol/kg by the fourth day of feeding. PCCr was positively correlated with CCr, and ATP concentration and pH declined with increasing PCCr. Feeding with 1% CCr in water induced an apparent saturated level of PCCr, suggesting that CCr quantization may not be necessary for quantifying expression of CK in mice. These findings support the possibility of using (31)P MRS to noninvasively monitor hepatocyte transplant success with CK-expressing hepatocytes.

Lipid profiling of cancerous and benign gallbladder tissues by 1H NMR spectroscopy.

Qualitative and quantitative (1) H NMR analysis of lipid extracts of gallbladder tissue in chronic cholecystitis (CC, benign) (n = 14), xanthogranulomatous cholecystitis (XGC, intermediate) (n = 9) and gallbladder cancer (GBC, malignant) (n = 8) was carried out to understand the mechanisms involved in the transformation of benign gallbladder tissue to intermediate and malignant tissue. The results revealed alterations in various tissue lipid components in gallbladder in CC, XGC and GBC. The difference in the nature of lipid components in benign and malignant disease may aid in the identification of the biological pathways involved in the etiopathogenesis of GBC. This is the first study on lipid profiling of gallbladder tissue by (1) H NMR spectroscopy, and has possible implications for the development of future diagnostic approaches.

Abnormal small intestinal permeability in patients with idiopathic malabsorption in tropics (tropical sprue) does not change even after successful treatment.

BACKGROUND: Though tropical sprue (TS) is common in tropics, studies on small intestinal permeability (SIP) in TS are scant. METHOD: SIP was evaluated using (1)H nuclear magnetic resonance (NMR) spectroscopy of urinary lactulose and mannitol in 24 patients with TS (22 before and 15 after treatment with tetracycline and folate) and in 31 healthy subjects (HS). Effect of treatment of TS on SIP and its relationship with outcome were studied. RESULT: Subjects were comparable in terms of age and gender. Before treatment, urinary lactulose (0.24 mmol, 0-1.09 mmol versus 0.09 mmol, 0-0.68 mmol, P=0.02) and lactulose-to-mannitol (L/M) ratio (0.11, 0-0.41 versus 0.042, 0-0.26, P=0.001) were higher in TS than in HS, though mannitol was comparable (2.7 mmol, 0.61-10.5 mmol versus 3.8 mmol, 1.3-16.4 mmol, P=0.08). Patients improved after treatment [stool frequency (9, 4-20/day versus 1, 1-2/day, P<0.0001), weight (44.4, 32-69 kg, versus 56, 39-84 kg, P<0.0001), fecal fat (10.1, 6-26 g/24 h versus 4.4, 3.0-6.7 g/24 h, P<0.0001), D-xylose (0.57, 0.28-1.2 g/5 g/5 h versus 1.1, 0.2-2.1 g/5 g/5 h, P<0.0001), and small intestinal bacterial overgrowth (SIBO) resolved in 10/24 (41.7%) versus 1/15 (6.6%), P=0.02]. Though urinary lactulose (0.17, 0-4.3 mmol versus 0.09, 0-0.68 mmol, P=0.11) and mannitol (2.17, 0.8-36.7 mmol versus 3.84, 1.3-16.4 mmol, P=0.06) were comparable, L/M ratio was higher in TS than in HS (0.09, 0-0.22 versus 0.042, 0-0.26, P=0.002). L/M ratio was more often abnormal (cutoff 0.078) in TS than in HS [14/22 (63.6%) versus 3/31 (9.7%); P=0.0001], which persisted even after treatment [9/15 (60%) as compared with HS; P=0.0006]. Persistently abnormal SIP was associated with less weight gain and frequent stools following treatment. CONCLUSION: SIP is often abnormal in TS and remains unchanged even after successful treatment that was associated with less weight gain and more frequent stool.

Assessment of small intestinal permeability using 1H-NMR spectroscopy.

BACKGROUND: Evaluation of small intestinal permeability (SIP) is based on the estimation of the urinary excretion ratio of a large and a small molecule (lactulose and mannitol, L/M) after oral administration. We evaluated SIP using 1H-NMR spectroscopy. METHODS: In-vitro experiments on known concentration of mannitol and lactulose solutions were performed to measure accuracy and precession of quantification using 1H-NMR spectroscopy. Eighteen patients with malabsorption syndrome (MAS) and 28 healthy subjects (HS) underwent SIP evaluation using L/M excretion ratio over 6-h after oral administration of 15 mL (10g) lactulose and 5 g mannitol using 1H-NMR spectroscopy and trimethyl silyl propionic acid as external reference and for quantification. RESULTS: Median errors of estimation of mannitol and lactulose were 5% (range 1.2 to 5) and 1.3% (range 0.2 to 1.3), respectively in-vitro. Patients with MAS excreted higher quantity of lactulose in urine than HS (median 0.33 mmol vs 0.12, 0 to .676 mmol, p<0.008). There was a trend towards lower urinary excretion of mannitol in patients with MAS than HS (median 3.58, range 0.61 to 15.77 mmol vs. 3.82, 1.34 to 16.42 mmol, p = ns). L/M ratio was higher among patients with MAS as compared to HS (median 0.1172 vs 0.045, p< 0.002). A cut-off value of L/M excretion ratio by receiver-operating characteristic (ROC) curve of 0.049 had a sensitivity and specificity of 72% and 61%, respectively; a cut-off value of 0.078 had a specificity of 90% but low sensitivity (67%). Area under ROC curve was 0.77. CONCLUSION: 1H-NMR spectroscopy is an analytical tool for assessment of SIP with reasonable sensitivity and specificity.