First report about the mode of action of combined butafosfan and cyanocobalamin on hepatic metabolism in nonketotic early lactating cows

The primary aim was to investigate the effect of combined butafosfan and cyanocobalamin on liver metabolism in early lactating cows through mRNA expression measurements of genes encoding 31 enzymes and transport proteins of major metabolic processes in the liver using 16 multiparous early lactating dairy cows. The treatments included i.v. injection of 10 mL/100 kg of body weight combined butafosfan and cyanocobalamin (TG, n = 8) on 3 d consecutively at 25 +/- 3 d in milk or injection with physiological saline solution similarly applied (CG, n = 8). Results include a higher daily milk production for TG cows (41.1 +/- 0.9 kg, mean +/- SEM) compared with CG cows (39.5 +/- 0.7 kg). In plasma, the concentration of inorganic phosphorus was lower in the TG cows (1.25 +/- 0.08 mmol/L) after the treatment than in the CG cows (1.33 +/- 0.07 mmol/L). The plasma beta-hydroxybutyrate concentration was 0.65 +/- 0.13 mmol/L for all cows before the treatment, and remained unaffected post treatment. The unique result was that in the liver, the mRNA abundance of acyl-coenzyme A synthetase long-chain family member 1, involved in fatty acid oxidation and biosynthesis, was lower across time points after the treatment for TG compared with CG cows (17.5 +/- 0.15 versus 18.1 +/- 0.24 cycle threshold, log(2), respectively). In conclusion, certain effects of combined butafosfan and cyanocobalamin were observed on mRNA abundance of a gene in the liver of nonketotic early lactating cows.

Coordinated gene expression in adipose tissue and liver differs between cows with high or low NEFA concentrations in early lactation

Dairy cows with high and low plasma non-esterified fatty acid (NEFA) concentrations in early lactation were compared for plasma parameters and mRNA expression of genes in liver and subcutaneous adipose tissue. The study involved 16 multiparous dairy cows with a plasma NEFA concentration of >500 mumol/l [n = 8, high NEFA (HNEFA)] and <140 mumol/l [n = 8, low NEFA (LNEFA)] in the first week post-partum (pp). Blood samples, adipose and liver tissues were collected on day 1 (+1d) and at week 3 pp (+3wk). Blood plasma was assayed for concentrations of metabolites and hormones. Subcutaneous adipose and liver tissues were analysed for mRNA abundance by real-time qRT-PCR encoding parameters related to lipid metabolism. Results showed that mean daily milk yield and milk fat quantity were higher in HNEFA than in LNEFA cows (p < 0.01), and the NEB was more negative in HNEFA than in LNEFA in +3wk too (p < 0.05). HNEFA cows had slightly lower (p < 0.1) insulin concentrations than LNEFA cows across the study period, and the body condition score decreased more from +1d to +3wk in HNEFA than in LNEFA (p = 0.09). The mRNA abundance of genes in the liver related to fatty acid oxidation (carnitine palmitoyltransferase 2 and very long chain acyl-coenzyme A dehydrogenase) and ketogenesis (3-hydroxy-3-methylglutaryl-coenzyme A synthase 2) were lower in HNEFA than in LNEFA cows. No differences between the two groups were observed for mRNA expression of genes in adipose tissue. The number of calculated significant correlation coefficients (moderately strong) between parameters in the liver and in adipose tissue was nearly similar on +1d, and higher for HNEFA compared with LNEFA cows in +3wk. In conclusion, dairy cows with high compared with low plasma NEFA concentrations in early lactation show differentially synchronized mRNA expression of genes in adipose tissue and liver in +3wk that suggests a different orchestrated homeorhetic regulation of lipid metabolism.

Variation in hepatic regulation of metabolism during the dry period and in early lactation in dairy cows

The purpose of this study was to investigate variations in hepatic regulation of metabolism during the dry period, after parturition, and in early lactation in dairy cows. For this evaluation, cows were divided into 2 groups based on the plasma concentration of beta-hydroxybutyric acid (BHBA) in wk 4 postpartum (PP; group HB, BHBA >0.75 mmol/L; group LB, BHBA <0.75 mmol/L, respectively). Liver biopsies were obtained from 28 cows at drying off (mean 59 +/- 8 d antepartum), on d 1, and in wk 4 and 14 PP. Blood samples were collected every 2 wk during this entire period. Liver samples were analyzed for mRNA abundance of genes related to carbohydrate metabolism (pyruvate carboxylase, PC; phosphoenolpyruvate carboxykinase, PEPCK; citrate synthase, CS), fatty acid biosynthesis (ATP citrate lyase, ACLY) and oxidation (acyl-CoA synthetase long-chain, ACSL; carnitine palmitoyltransferase 1A, CPT 1A; carnitine palmitoyltransferase 2, CPT 2; acyl-coenzyme A dehydrogenase very long chain, ACADVL), cholesterol biosynthesis (3-hydroxy-3-methylglutaryl-coenzyme A synthase 1, HMGCS1), ketogenesis (3-hydroxy-3-methylglutaryl-coenzyme A synthase 2, HMGCS2), and of genes encoding the transcription factors peroxisome proliferator-activated receptor alpha (PPARalpha), peroxisome proliferator-activated receptor gamma (PPARgamma), and sterol regulatory element binding factor 1 (SREBF1). Blood plasma was assayed for concentrations of glucose, BHBA, nonesterified fatty acids, cholesterol, triglycerides, insulin, insulin-like growth factor-I, and thyroid hormones. In both groups, plasma parameters followed a pattern usually observed in dairy cows. However, changes were moderate and the energy balance in cows turned positive in wk 7 PP for both groups. Additionally, the energy balance and milk yield were similar for both groups after parturition onwards. Significant group effects were found at drying off, when plasma concentrations of triglycerides were higher in LB than in HB, and in wk 4 PP, when plasma concentrations of glucose and IGF-I were lower in HB than in LB. Similarly, moderate changes in mRNA expression of hepatic genes between the different time points were observed, although HB cows showed more adaptive performance than LB cows based on changes in mRNA expression of PEPCKc, PEPCKm, CS, CPT 1A, CPT 2, and PPARalpha. Part of the variation measured in this study was explained by parity. Significant Spearman rank correlation coefficients between the variables were not similar at each time point and were not similar between the groups at each time point, suggesting that metabolic regulation differs between cows. In conclusion, metabolic regulation in dairy cows is a dynamic system, and differs obviously between cows at different metabolic stages related to parturition.

Highly efficient ketone body treatment in multiple acyl-CoA dehydrogenase deficiency-related leukodystrophy.

BACKGROUND Multiple acyl-CoA dehydrogenase deficiency- (MADD-), also called glutaric aciduria type 2, associated leukodystrophy may be severe and progressive despite conventional treatment with protein- and fat-restricted diet, carnitine, riboflavin, and coenzyme Q10. Administration of ketone bodies was described as a promising adjunct, but has only been documented once. METHODS We describe a Portuguese boy of consanguineous parents who developed progressive muscle weakness at 2.5 y of age, followed by severe metabolic decompensation with hypoglycaemia and coma triggered by a viral infection. Magnetic resonance (MR) imaging showed diffuse leukodystrophy. MADD was diagnosed by biochemical and molecular analyses. Clinical deterioration continued despite conventional treatment. Enteral sodium D,L-3-hydroxybutyrate (NaHB) was progressively introduced and maintained at 600 mg/kg BW/d (≈3% caloric need). Follow up was 3 y and included regular clinical examinations, biochemical studies, and imaging. RESULTS During follow up, the initial GMFC-MLD (motor function classification system, 0 = normal, 6 = maximum impairment) level of 5-6 gradually improved to 1 after 5 mo. Social functioning and quality of life recovered remarkably. We found considerable improvement of MR imaging and spectroscopy during follow up, with a certain lag behind clinical recovery. There was some persistent residual developmental delay. CONCLUSION NaHB is a highly effective and safe treatment that needs further controlled studies.

The Gup1 homologue of Trypanosoma brucei is a GPI glycosylphosphatidylinositol remodelase

Glycosylphosphatidylinositol (GPI) lipids of Trypanosoma brucei undergo lipid remodelling, whereby longer fatty acids on the glycerol are replaced by myristate (C14:0). A similar process occurs on GPI proteins of Saccharomyces cerevisiae where Per1p first deacylates, Gup1p subsequently reacylates the anchor lipid, thus replacing a shorter fatty acid by C26:0. Heterologous expression of the GUP1 homologue of T. brucei in gup1Delta yeast cells partially normalizes the gup1Delta phenotype and restores the transfer of labelled fatty acids from Coenzyme A to lyso-GPI proteins in a newly developed microsomal assay. In this assay, the Gup1p from T. brucei (tbGup1p) strongly prefers C14:0 and C12:0 over C16:0 and C18:0, whereas yeast Gup1p strongly prefers C16:0 and C18:0. This acyl specificity of tbGup1p closely matches the reported specificity of the reacylation of free lyso-GPI lipids in microsomes of T. brucei. Depletion of tbGup1p in trypanosomes by RNAi drastically reduces the rate of myristate incorporation into the sn-2 position of lyso-GPI lipids. Thus, tbGup1p is involved in the addition of myristate to sn-2 during GPI remodelling in T. brucei and can account for the fatty acid specificity of this process. tbGup1p can act on GPI proteins as well as on GPI lipids.

Combined alpha-methylacyl coenzyme A racemase/p53 analysis to identify dysplasia in inflammatory bowel disease

Identification of dysplasia in inflammatory bowel disease represents a major challenge for both clinicians and pathologists. Clear diagnosis of dysplasia in inflammatory bowel disease is sometimes not possible with biopsies remaining "indefinite for dysplasia." Recent studies have identified molecular alterations in colitis-associated cancers, including increased protein levels of alpha-methylacyl coenzyme A racemase, p53, p16 and bcl-2. In order to analyze the potential diagnostic use of these parameters in biopsies from inflammatory bowel disease, a tissue microarray was manufactured from colons of 54 patients with inflammatory bowel disease composed of 622 samples with normal mucosa, 78 samples with inflammatory activity, 6 samples with low-grade dysplasia, 12 samples with high-grade dysplasia, and 66 samples with carcinoma. In addition, 69 colonoscopic biopsies from 36 patients with inflammatory bowel disease (28 low-grade dysplasia, 8 high-grade dysplasia, and 33 indefinite for dysplasia) were included in this study. Immunohistochemistry for alpha-methylacyl coenzyme A racemase, p53, p16 and bcl-2 was performed on both tissue microarray and biopsies. p53 and alpha-methylacyl coenzyme A racemase showed the most discriminating results, being positive in most cancers (77.3% and 80.3%) and dysplasias (94.4% and 94.4%) but only rarely in nonneoplastic epithelium (1.6% and 9.4%; P < .001). Through combining the best discriminators, p53 and alpha-methylacyl coenzyme A racemase, a stronger distinction between neoplastic tissues was possible. Of all neoplastic lesions, 75.8% showed a coexpression of alpha-methylacyl coenzyme A racemase and p53, whereas this was found in only 4 of 700 nonneoplastic samples (0.6%). alpha-methylacyl coenzyme A racemase/p53 coexpression was also found in 10 of 33 indefinite for dysplasia biopsies (30.3 %), suggesting a possible neoplastic transformation in these cases. Progression to dysplasia or carcinoma was observed in 3 of 10 p53/alpha-methylacyl coenzyme A racemase-positive, indefinite-for-dysplasia cases, including 1 of 7 cases without and 2 of 3 cases with p53 mutation. It is concluded that combined alpha-methylacyl coenzyme A racemase/p53 analysis may represent a helpful tool to confirm dysplasia in inflammatory bowel disease.

Mutation screening of the medium-chain acyl-CoA dehydrogenase (MCAD) and the ornithine transcarbamylase (OTC) genes by multiplex PCR amplification and sequencing

BACKGROUND: Sequencing based mutation screening assays of genes encompassing large numbers of exons could be substantially optimized by multiplex PCR, which enables simultaneous amplification of many targets in one reaction. In the present study, a multiplex PCR protocol originally developed for fragment analysis was evaluated for sequencing based mutation screening of the ornithine transcarbamylase (OTC) and the medium-chain acyl-CoA dehydrogenase (MCAD) genes. METHODS: Single exon and multiplex PCR protocols were applied to generate PCR templates for subsequent DNA sequencing of all exons of the OTC and the MCAD genes. For each PCR protocol and using the same DNA samples, 66 OTC and 98 MCAD sequence reads were generated. The sequences derived from the two different PCR methods were compared at the level of individual signal-to-noise ratios of the four bases and the proportion of high-quality base-signals. RESULTS: The single exon and the multiplex PCR protocol gave qualitatively comparable results for the two genes. CONCLUSIONS: Many existing sequencing based mutation analysis protocols may be easily optimized with the proposed method, since the multiplex PCR protocol was successfully applied without any re-design of the PCR primers and other optimization steps for generating sequencing templates for the OTC and MCAD genes, respectively.

Hepatic gene expression involved in glucose and lipid metabolism in transition cows: effects of fat mobilization during early lactation in relation to milk performance and metabolic changes.

Insufficient feed intake during early lactation results in elevated body fat mobilization to meet energy demands for milk production. Hepatic energy metabolism is involved by increasing endogenous glucose production and hepatic glucose output for milk synthesis and by adaptation of postcalving fuel oxidation. Given that cows differ in their degree of fat mobilization around parturition, indicated by variable total liver fat concentration (LFC), the study investigated the influence of peripartum fat mobilization on hepatic gene expression involved in gluconeogenesis, fatty acid oxidation, ketogenesis, and cholesterol synthesis, as well as transcriptional factors referring to energy metabolism. German Holstein cows were grouped according to mean total LFC on d 1, 14, and 28 after parturition as low [<200mg of total fat/g of dry matter (DM); n=10], medium (200-300 mg of total fat/g of DM; n=10), and high (>300 mg of total fat/g of DM; n=7), indicating fat mobilization during early lactation. Cows were fed total mixed rations ad libitum and held under equal conditions. Liver biopsies were taken at d 56 and 15 before and d 1, 14, 28, and 49 after parturition to measure mRNA abundances of pyruvate carboxylase (PC); phosphoenolpyruvate carboxykinase; glucose-6-phosphatase; propionyl-coenzyme A (CoA) carboxylase α; carnitine palmitoyl-transferase 1A (CPT1A); acyl-CoA synthetase, long chain 1 (ASCL1); acyl-CoA dehydrogenase, very long chain; 3-hydroxy-3-methylglutaryl-CoA synthase 1 and 2; sterol regulatory element-binding factor 1; and peroxisome proliferator-activated factor α. Total LFC postpartum differed greatly among cows, and the mRNA abundance of most enzymes and transcription factors changed with time during the experimental period. Abundance of PC mRNA increased at parturition to a greater extent in high- and medium-LFC groups than in the low-LFC group. Significant LFC × time interactions for ACSL1 and CPT1A during the experimental period indicated variable gene expression depending on LFC after parturition. Correlations between hepatic gene expression and performance data and plasma concentrations of metabolites and hormones showed time-specific relations during the transition period. Elevated body fat mobilization during early lactation affected gene expression involved in gluconeogenesis to a greater extent than gene expression involved in lipid metabolism, indicating the dependence of hepatic glucose metabolism on hepatic lipid status and fat mobilization during early lactation.

Inhibition of tissue transglutaminase sensitizes TRAIL-resistant lung cancer cells through upregulation of death receptor 5

Tissue transglutaminase (TG2) is implicated in cellular processes such as apoptosis and cell migration. Its acyl transferase activity cross-links certain proteins, among them transcription factors were described. We show here that the TG2 inhibitor KCC009 reversed resistance to tumor necrosis factor-related apoptosis-inducing factor (TRAIL) in lung cancer cells. Sensitization required upregulation of death receptor 5 (DR5) but not of death receptor 4. Upregulation of DR5 involved the first intron of the DR5 gene albeit it was independent from p53 and nuclear factor kappa B. In conclusion, inhibition of tissue transglutaminase provides an interesting strategy for sensitization to TRAIL-induced apoptosis in p53-deficient lung cancer cells.

Lipid remodelling of glycosylphosphatidylinositol (GPI) glycoconjugates in procyclic-form trypanosomes: biosynthesis and processing of GPIs revisited

The African trypanosome, Trypanosoma brucei, has been used as a model to study the biosynthesis of GPI (glycosylphosphatidylinositol) anchors. In mammalian (bloodstream)-form parasites, diacyl-type GPI precursors are remodelled in their lipid moieties before attachment to variant surface glycoproteins. In contrast, the GPI precursors of insect (procyclic)-form parasites, consisting of lyso-(acyl)PI (inositol-acylated acyl-lyso-phosphatidylinositol) species, remain unaltered before protein attachment. By using a combination of metabolic labelling, cell-free assays and complementary MS analyses, we show in the present study that GPI-anchored glycoconjugates in T. congolense procyclic forms initially receive tri-acylated GPI precursors, which are subsequently de-acylated either at the glycerol backbone or on the inositol ring. Chemical and enzymatic treatments of [3H]myristate-labelled lipids in combination with ESI-MS/MS (electrospray ionization-tandem MS) and MALDI-QIT-TOF-MS3 (matrix-assisted laser-desorption ionization-quadrupole ion trap-time-of-flight MS) analyses indicate that the structure of the lipid moieties of steady-state GPI lipids from T. congolense procyclic forms consist of a mixture of lyso-(acyl)PI, diacyl-PI and diacyl-(acyl)PI species. Interestingly, some of these species are myristoylated at the sn-2 position. To our knowledge, this is the first demonstration of lipid remodelling at the level of protein- or polysaccharide-linked GPI anchors in procyclic-form trypanosomes.

Can molecular markers stratify the diagnostic value of high-grade prostatic intraepithelial neoplasia?

The diagnostic performance of isolated high-grade prostatic intraepithelial neoplasia in prostatic biopsies has recently been questioned, and molecular analysis of high-grade prostatic intraepithelial neoplasia has been proposed for improved prediction of prostate cancer. Here, we retrospectively studied the value of isolated high-grade prostatic intraepithelial neoplasia and the immunohistochemical markers ?-methylacyl coenzyme A racemase, Bcl-2, annexin II, and Ki-67 for better risk stratification of high-grade prostatic intraepithelial neoplasia in our local Swiss population. From an initial 165 diagnoses of isolated high-grade prostatic intraepithelial neoplasia, we refuted 61 (37%) after consensus expert review. We used 30 reviewed high-grade prostatic intraepithelial neoplasia cases with simultaneous biopsy prostate cancer as positive controls. Rebiopsies were performed in 66 patients with isolated high-grade prostatic intraepithelial neoplasia, and the median time interval between initial and repeat biopsy was 3 months. Twenty (30%) of the rebiopsies were positive for prostate cancer, and 10 (15%) showed persistent isolated high-grade prostatic intraepithelial neoplasia. Another 2 (3%) of the 66 patients were diagnosed with prostate cancer in a second rebiopsy. Mean prostate-specific antigen serum levels did not significantly differ between the 22 patients with prostate cancer and the 44 without prostate cancer in rebiopsies, and the 30 positive control patients, respectively (median values, 8.1, 7.7, and 8.8 ng/mL). None of the immunohistochemical markers, including ?-methylacyl coenzyme A racemase, Bcl-2, annexin II, and Ki-67, revealed a statistically significant association with the risk of prostate cancer in repeat biopsies. Taken together, the 33% risk of being diagnosed with prostate cancer after a diagnosis of high-grade prostatic intraepithelial neoplasia justifies rebiopsy, at least in our not systematically prostate-specific antigen-screened population. There is not enough evidence that immunohistochemical markers can reproducibly stratify the risk of prostate cancer after a diagnosis of isolated high-grade prostatic intraepithelial neoplasia.

Plasma leptin and mRNA expression of lipogenesis and lipolysis-related factors in bovine adipose tissue around parturition

The objective was to study changes in plasma leptin concentration parallel to changes in the gene expression of lipogenic- and lipolytic-related genes in adipose tissue of dairy cows around parturition. Subcutaneous fat biopsies were taken from 27 dairy cows in week 8 antepartum (a.p.), on day 1 postpartum (p.p.) and in week 5 p.p. Blood samples were assayed for concentrations of leptin and non-esterified fatty acids (NEFA). Subcutaneous adipose tissue was analysed for mRNA abundance by real-time qRT-PCR encoding for leptin, adiponectin receptor 1 (AdipoR1), adiponectin receptor 2 (AdipoR2), hormones-sensitive lipase (HSL), perilipin (PLIN), lipoprotein lipase (LPL), acyl-CoA synthase long-chain family member 1 (ACSL1), acetyl-CoA carboxylase (ACC), fatty acid synthase (FASN) and glycerol-3-phosphate dehydrogenase 2 (GPD2). Body weight and body condition score of the cows were lower after parturition than before parturition. The calculated energy balance was negative in week 1 and 5 p.p., with higher negative energy balance in week 1 p.p. compared with that in week 5 p.p. On day 1 p.p., highest concentrations of NEFA (353.3 mumol/l) were detected compared with the other biopsy time-points (210.6 and 107.7 mumol/l, in week 8 a.p., and week 5 p.p. respectively). Reduced plasma concentrations of leptin during p.p. when compared with a.p. would favour increasing metabolic efficiency and energy conservation for mammary function and reconstitution of body reserves. Lower mRNA abundance of ACC and FASN expression on day 1 p.p. compared with other biopsy time-points suggests an attenuation of fatty acid synthesis in subcutaneous adipose tissue shortly after parturition. Gene expression of AdipoR1, AdipoR2, HSL, PLIN, LPL, ACSL1 and GPD2 was unchanged over time.

Disruption of the histidine triad nucleotide-binding hint2 gene in mice affects glycemic control and mitochondrial function

The histidine triad nucleotide-binding (Hint2) protein is a mitochondrial adenosine phosphoramidase expressed in liver and pancreas. Its physiological function is unknown. To elucidate the role of Hint2 in liver physiology, the Hint2 gene was deleted. Hint2(-/-) and Hint2(+/+) mice were generated in a mixed C57Bl6/J x 129Sv background. At 20 weeks, the phenotypic changes in Hint2(-/-) relative to Hint2(+/+) mice were an accumulation of hepatic triglycerides, decreased tolerance to glucose, a defective counter-regulatory response to insulin-provoked hypoglycaemia, an increase in plasma interprandial insulin but a decrease in glucose stimulated insulin secretion and defective thermoregulation upon fasting. Leptin mRNA in adipose tissue and plasma leptin were elevated. In mitochondria from Hint2(-/-) hepatocytes, state 3 respiration was decreased, a finding confirmed in HepG2 cells where HINT2 mRNA was silenced. The linked complex II to III electron transfer was decreased in Hint2(-/-) mitochondria, which was accompanied by a lower content of coenzyme Q. HIF-2α expression and the generation of reactive oxygen species were increased. Electron microscopy of mitochondria in Hint2(-/-) mice aged 12 months revealed clustered, fused organelles. The hepatic activities of 3-hydroxyacyl-CoA dehydrogenase short chain and glutamate dehydrogenase (GDH) were decreased by 68% and 60%, respectively, without a change in protein expression. GDH activity was similarly decreased in HINT2-silenced HepG2 cells. When measured in the presence of purified sirtuin 3, latent GDH activity was recovered (126% in Hint2(-/-) vs. 83% in Hint2(+/+) ). This suggests a greater extent of acetylation in Hint2(-/-) than in Hint2(+/+) . Conlusions: Hint2 positively regulates mitochondrial lipid metabolism and respiration, and glucose homeostasis. The absence of Hint2 provokes mitochondrial deformities and a change in the pattern of acetylation of selected proteins. (HEPATOLOGY 2012.).

Quantification of plasma carnitine and acylcarnitines by high-performance liquid chromatography-tandem mass spectrometry using online solid-phase extraction

Carnitine is an amino acid derivative that plays a key role in energy metabolism. Endogenous carnitine is found in its free form or esterified with acyl groups of several chain lengths. Quantification of carnitine and acylcarnitines is of particular interest for screening for research and metabolic disorders. We developed a method with online solid-phase extraction coupled to high-performance liquid chromatography and tandem mass spectrometry to quantify carnitine and three acylcarnitines with different polarity (acetylcarnitine, octanoylcarnitine, and palmitoylcarnitine). Plasma samples were deproteinized with methanol, loaded on a cation exchange trapping column and separated on a reversed-phase C8 column using heptafluorobutyric acid as an ion-pairing reagent. Considering the endogenous nature of the analytes, we quantified with the standard addition method and with external deuterated standards. Solid-phase extraction and separation were achieved within 8 min. Recoveries of carnitine and acylcarnitines were between 98 and 105 %. Both quantification methods were equally accurate (all values within 84 to 116 % of target concentrations) and precise (day-to-day variation of less than 18 %) for all carnitine species and concentrations analyzed. The method was used successfully for determination of carnitine and acylcarnitines in different human samples. In conclusion, we present a method for simultaneous quantification of carnitine and acylcarnitines with a rapid sample work-up. This approach requires small sample volumes and a short analysis time, and it can be applied for the determination of other acylcarnitines than the acylcarnitines tested. The method is useful for applications in research and clinical routine.

Analysis of lorazepam and its 30-glucuronide in human urine by capillary electrophoresis: evidence for the formation of two distinct diastereoisomeric glucuronides

Lorazepam (LOR) is a 3-hydroxy-1,4-benzodiazepine that is chiral and undergoes enantiomerization at room temperature. In humans, about 75% of the administered dose of LOR is excreted in the urine as its 30-glucuronide. CE-MS with negative ESI was used to confirm the presence of LOR-30-glucuronide in urines that stemmed from a healthy individual who ingested 1 or 2 mg LOR, whereas free LOR could be detected in extracts prepared from enzymatically hydrolyzed urines. As the 30-glucuronidation reaction occurs at the chiral center of the molecule, two diastereoisomers can theoretically be formed, molecules that can no longer interconvert. The stereoselective formation of LOR glucuronides in humans and in vitro was investigated. MEKC analysis of extracts of the nonhydrolyzed urines suggested the presence of the two different LOR glucuronides in the urine. The formation of the same two diastereoisomers was also observed in vitro employing incubations of LOR with human liver microsomes in the presence of uridine 5'-diphospho-glucuronic acid as coenzyme. The absence of other coenzymes excluded the formation of phase I or other phase II metabolites of LOR. Both results revealed a stereoselectivity, one diastereoisomer being formed in a higher amount than the other. After enzymatic hydrolysis using beta-glucuronidase, these peaks could not be detected any more. Instead, LOR was monitored. Analysis of the extracts prepared from enzymatically hydrolyzed urines by MEKC in the presence of 2-hydroxypropyl-beta-CD revealed the enantiomerization process of LOR (observation of two peaks of equal magnitude connected with a plateau zone). The data presented provide for the first time the evidence of the stereoselectivity of the LOR glucuronidation in humans.