Andreas Staempfli | Roche Products Ltd (original) (raw)

Papers by Andreas Staempfli

Research paper thumbnail of A new matrix for fast-atom bombardment analysis of corrins

Rapid Communications in Mass Spectrometry, 1991

2,3-dihydroxypropyl benzyl ether, a glycerol derivative, is a suitable matrix for fast-atom bomba... more 2,3-dihydroxypropyl benzyl ether, a glycerol derivative, is a suitable matrix for fast-atom bombardment analysis. It has been shown to be superior to glycerol and thioglycerol for the detection of molecular ions of cobyrates.

Research paper thumbnail of Effect of Dalcetrapib and Torcetrapib on Noncholesterol Markers of Cholesterol Homeostasis in the Hamster

Journal of Clinical Lipidology, 2011

Results: Fifty-eight patients were randomized (39MIPO, 19 PBO) at 26 clinical centers in 6 countr... more Results: Fifty-eight patients were randomized (39MIPO, 19 PBO) at 26 clinical centers in 6 countries. Forty-five (78%) patients completed the treatment period. Twelve (31%) MIPO and 1 (5%) PBO patient(s) withdrew (8 of the MIPO and the 1 PBO withdrawals were caused by an adverse event [AE]). LDL-C was reduced by 36% from a mean baseline level of 276 mg/dL in the MIPO group vs. an increase of 13% from a BL of 249 mg/dL in the PBO group (p , 0.001). This represents a 101 mg/dL mean reduction of LDL-C in theMIPOgroup. Similarly,MIPOproduced highly significant (P , .001) reductions in other atherogenic lipoproteins, eg, ApoB and Lp(a), there was no change in HDL-C. The most common on-treatment AEs were injection site reactions (90%MIPO, 32% PBO) and flu-like symptoms (46% MIPO, 21% PBO). Six (15%) MIPO patients and no PBO patients had ALT 3!ULNonconsecutivemeasuresatleast7daysapart.OneMIPOpatienthadatransientALT3!ULN on consecutive measures at least 7 days apart. One MIPO patient had a transient ALT 3!ULNonconsecutivemeasuresatleast7daysapart.OneMIPOpatienthadatransientALT10! ULN. ALT elevations were not associated with clinically significant increases in bilirubin. Conclusions: MIPO treatment significantly reduced LDL-C and ApoB in patients with severe hypercholesterolemia. The data support the potential utility of MIPO as a pharmacologic option for additional LDL C lowering in patients with heterozygous hypercholesterolemia not adequately controlled under existing LLTs.

Research paper thumbnail of Modeling the Effects of Severe Metabolic Disease by Genome Editing of hPSC-Derived Endothelial Cells Reveals an Inflammatory Phenotype

International Journal of Molecular Sciences

The kinase AKT2 (PKB) is an important mediator of insulin signaling, for which loss-of-function k... more The kinase AKT2 (PKB) is an important mediator of insulin signaling, for which loss-of-function knockout (KO) mutants lead to early onset diabetes mellitus, and dominant active mutations lead to early development of obesity and endothelial cell (EC) dysfunction. To model EC dysfunction, we used edited human pluripotent stem cells (hPSCs) that carried either a homozygous deletion of AKT2 (AKT2 KO) or a dominant active mutation (AKT2 E17K), which, along with the parental wild type (WT), were differentiated into ECs. Profiling of EC lines indicated an increase in proinflammatory and a reduction in anti-inflammatory fatty acids, an increase in inflammatory chemokines in cell supernatants, increased expression of proinflammatory genes, and increased binding to the EC monolayer in a functional leukocyte adhesion assay for both AKT2 KO and AKT2 E17K. Collectively, these findings suggest that vascular endothelial inflammation that results from dysregulated insulin signaling (homeostasis) ma...

Research paper thumbnail of How Female Mice Attract Males: A Urinary Volatile Amine Activates a Trace Amine-Associated Receptor That Induces Male Sexual Interest

Frontiers in pharmacology, 2018

Individuals of many species rely on odors to communicate, find breeding partners, locate resource... more Individuals of many species rely on odors to communicate, find breeding partners, locate resources and sense dangers. In vertebrates, odorants are detected by chemosensory receptors of the olfactory system. One class of these receptors, the trace amine-associated receptors (TAARs), was recently suggested to mediate male sexual interest and mate choice. Here we tested this hypothesis in mice by generating a cluster deletion mouse () lacking all TAARs expressed in the olfactory epithelium, and evaluating transduction pathways from odorants to TAARs, neural activity and behaviors reflecting sexual interest. We found that a urinary volatile amine, isobutylamine (IBA), was a potent ligand for TAAR3 (but not TAAR1, 4, 5, and 6). When males were exposed to IBA, brain regions associated with sexual behaviors were less active in than in wild type males. Accordingly, males spent less time sniffing both the urine of females and pure IBA than wild type males. This is the first demonstration of ...

Research paper thumbnail of Lewy pathology in Parkinson's disease consists of a crowded organellar membranous medley

Parkinson's disease, the most common age-related movement disorder, is a progressive neurodeg... more Parkinson's disease, the most common age-related movement disorder, is a progressive neurodegenerative disease with unclear etiology. Key neuropathological hallmarks are Lewy bodies and Lewy neurites, which are neuronal inclusions that are immunopositive for the protein alpha-synuclein. In-depth ultrastructural analysis of Lewy pathology is key to understanding pathogenesis and progression of the disease. Using correlative light and electron microscopy on postmortem brain tissue of Parkinson's patients, we discovered a crowded membranous medley of vesicular structures, dysmorphic mitochondria and disrupted cytoskeletal elements in Lewy bodies and Lewy neurites, rather than the widely expected proteinacious filaments. The collapse and crowding of central organellar components was confirmed by stimulated emission-depletion microscopy, and chemical and optical imaging. A high lipid content was confirmed by lipidomics. The findings indicate ill-defined subcellular protein-lipid ...

Research paper thumbnail of Abstract LB-085: RG70099: A novel, highly potent dual IDO1/TDO inhibitor to reverse metabolic suppression of immune cells in the tumor micro-environment

Research paper thumbnail of Procédé pour la préparation d'acide cyclohexanecarboxylique

Research paper thumbnail of Identification and structure of a family of syringolin variants : Unusual cyclic peptides from Pseudomonas syringae pv. syringae that elicit defense responses in rice

Microbiological Research, May 1, 1999

Pseudomonas syringae pv. syringae is recognized by the non-host plant Oryza sativa which reacts w... more Pseudomonas syringae pv. syringae is recognized by the non-host plant Oryza sativa which reacts with defense responses leading to induced resistance towards the rice blast fungus Pyricularia oryzae. We have previously shown that syring olin, a novel and unusual peptide secreted by P. syringae pv. syringae under appropriate conditions, is one of the molecular determinants by which rice plants can perceive the non-host pathogen. Here we show that syringolin is a member of a family of related compounds. We have isolated syringolin variants B to F and determined their structure using mass and NMR spectroscopic methods. These variants, which differ from each other by various modifications, are all able to induce defense responses upon application onto rice leaves.

Research paper thumbnail of Process for the preparation of cyclohexanecarboxylic acid derivatives

Research paper thumbnail of Determination of taurine metabolism by measurement of 15N-enriched taurine in cat urine by gas chromatography—mass spectrometry

Journal of Chromatography B: Biomedical Sciences and Applications, 1993

To understand the biological function of taurine, a study of taurine kinetics in the cat was unde... more To understand the biological function of taurine, a study of taurine kinetics in the cat was undertaken. This paper describes a method developed for the accurate determination of XSN-taurine enrichment in cat urine by gas chromatography-mass spectrometry. 15N-Taurine was given to six animals as an oral bolus dose of 20 mg/kg body weight, and the urine was pooled on a daily basis. The hydrolysed or non-hydrolysed urine samples (for total and free taurine, respectively) were directly derivatized without further purification. The N-pentafluorobenzoyl din -butyl amide derivative obtained was analysed, and the fragment [M-(di-n-butyl amide)] +, carrier of the labelled nitrogen atom, was selectively recorded at m/z 302 (14N-taurine) and m/z 303 (15N.taurine)" Calibration curves prepared in hydrolysed and non-hydrolysed urine samples spiked with 15N.taurin e gave similar slopes to the calibration curve prepared in water. The average coefficient of variation observed for the mole percent excess in the non-hydrolysed samples was 1.22% (n = 92) and for the hydrolysed urine 1.00% (n = 98). There was no significant difference between free and total taurine enrichment. The half-life of taurine in cat body was found to be 29.3 4-2.9 h and 35.0 + 1.4 h for free and total taurine, respectively (non-significant). The taurine body pool, calculated by extrapolation of the curve to zero time, had a value of 137 4-22 ng/kg and 157 4-I 1 mg/kg for free and total taurine, respectively.

Research paper thumbnail of First preparative biocatalytic hydrolysis and S-methylation of cyclic trithiocarbonates

Tetrahedron, 2002

ÐThe biocatalytic degradation of a cyclic trithiocarbonate, 6-amino-5-methoxycarbonyl-thieno[2,3-... more ÐThe biocatalytic degradation of a cyclic trithiocarbonate, 6-amino-5-methoxycarbonyl-thieno[2,3-d]-1,3-dithiole-2-thione 1, is reported. The product of the hydrolysis of the ®ve-membered ring by Pseudomonas chlororaphis ATCC 9447 oxidatively dimerized to form the tetrathiocin derivative 2. Furthermore, we performed the ®rst preparative biocatalytic methylation of an unnatural compound employing Emericella unguis ATCC 10032 by cleaving the dithiole ring 1 followed by methylation of both thiol groups to form the methylated product 4 in 64% isolated yield.

Research paper thumbnail of Determination of taurine metabolism by measurement of 15 N-enriched taurine in cat urine by gas chromatography—mass spectrometry

To understand the biological function of taurine, a study of taurine kinetics in the cat was unde... more To understand the biological function of taurine, a study of taurine kinetics in the cat was undertaken. This paper describes a method developed for the accurate determination of XSN-taurine enrichment in cat urine by gas chromatography-mass spectrometry. 15N-Taurine was given to six animals as an oral bolus dose of 20 mg/kg body weight, and the urine was pooled on a daily basis. The hydrolysed or non-hydrolysed urine samples (for total and free taurine, respectively) were directly derivatized without further purification. The N-pentafluorobenzoyl din -butyl amide derivative obtained was analysed, and the fragment [M-(di-n-butyl amide)] +, carrier of the labelled nitrogen atom, was selectively recorded at m/z 302 (14N-taurine) and m/z 303 (15N.taurine)" Calibration curves prepared in hydrolysed and non-hydrolysed urine samples spiked with 15N.taurin e gave similar slopes to the calibration curve prepared in water. The average coefficient of variation observed for the mole percent excess in the non-hydrolysed samples was 1.22% (n = 92) and for the hydrolysed urine 1.00% (n = 98). There was no significant difference between free and total taurine enrichment. The half-life of taurine in cat body was found to be 29.3 4-2.9 h and 35.0 + 1.4 h for free and total taurine, respectively (non-significant). The taurine body pool, calculated by extrapolation of the curve to zero time, had a value of 137 4-22 ng/kg and 157 4-I 1 mg/kg for free and total taurine, respectively.

Research paper thumbnail of 198 Effect of Dalcetrapib on Non-Cholesterol Markers of Cholesterol Homeostasis in Healthy Subjects

Background: Apolipoprotein A-I (apoA-I) induction represents a novel therapeutic approach to prom... more Background: Apolipoprotein A-I (apoA-I) induction represents a novel therapeutic approach to promoting high-density lipoprotein (HDL) functionality. The relationship between changes in conventional HDL measures and particle markers with apoA-I induction has not been investigated. Methods: The ASSERT study evaluated early biochemical changes with increasing doses of an apoA-I inducer (RVX-208 100-300 mg daily) for 12 weeks in statin-treated patients with stable coronary artery disease. Changes in HDL particle markers on 2D gel electrophoresis and NMR spectroscopy were characterized. Results: Administration of RVX-208 was associated with dose-dependent increases in levels of apoA-I (0.1−5.6%), HDL cholesterol (3.2−8.3%), large HDL particles (11.1-21.1%) on NMR and larger a1 particles (3.7−8.8%), but no change in small, lipid-deplete preb1 particles on 2D gel analysis. Significant correlations were observed between changes in HDL cholesterol and changes in total HDL particles (r = 0.44, p < 0.0001), large HDL (r = 0.55, p < 0.0001), small HDL (r = 0.22, p = 0.0002), preb1 (r = 0.16, p = 0.009) and a1 (r = 0.58, p < 0.0001) particles. Patients in the highest quartile increase in HDL cholesterol (>14%) demonstrated greater increases in HDL particle concentration (+10.1 vs −3.1%, p < 0.001) and size (+2.3 vs 0%, p < 0.001), large HDL particles (+46.9 vs −9.1%, p < 0.001), preb1 particles (+6.6 vs −5.1%, p = 0.04) and a1 particles (+29.5 vs −20.9%, p < 0.001) compared with lowest quartile. Conclusion: While changes in larger HDL particles predominate with apoA-I induction, patients with the most robust lipid response demonstrated increases in both small and large HDL particles. The functional consequences of these changes on atherosclerotic plaque remain to be determined.

Research paper thumbnail of Gas-phase dissociation mechanisms of dilithiated disaccharides: tandem mass spectrometry and semiempirical calculations

J Org Chem, 1992

Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilith... more Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilithiated disaccharides is used to differentiate the linkage position of three isomeric disaccharides. The mechanisms of dissociation proposed are based on the mass spectrometry, experimental data, and semiempirical calculations, the latter of which provide information on the stability of the deprotonated dilithiated precursor, (M + 2Li -H)+. Tandem mass spectrometry experiments indicate that, as in the case of monolithiated disaccharides, reducing ring opening occurs followed by two-, three-, and four-carbon chain neutral losses. Semiempirical calculations support the experimental data which suggest that one lithium is tetracoordinate between the two sugar rings, while the second lithium is dicoordinate forming a lithium alkoxide with one of the deprotonated hydroxyl groups of the reducing ring.

Research paper thumbnail of Gas-phase dissociation mechanisms of dilithiated disaccharides: tandem mass spectrometry and semiempirical calculations

The Journal of Organic Chemistry, 1992

Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilith... more Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilithiated disaccharides is used to differentiate the linkage position of three isomeric disaccharides. The mechanisms of dissociation proposed are based on the mass spectrometry, experimental data, and semiempirical calculations, the latter of which provide information on the stability of the deprotonated dilithiated precursor, (M + 2Li -H)+. Tandem mass spectrometry experiments indicate that, as in the case of monolithiated disaccharides, reducing ring opening occurs followed by two-, three-, and four-carbon chain neutral losses. Semiempirical calculations support the experimental data which suggest that one lithium is tetracoordinate between the two sugar rings, while the second lithium is dicoordinate forming a lithium alkoxide with one of the deprotonated hydroxyl groups of the reducing ring.

Research paper thumbnail of Study on the decomposition of the amadori compoundN-(1-deoxy-D-fructos-1-y1)-glycine in model systems: Quantification by fast atom bombardment tandem mass spectrometry

Biological Mass Spectrometry, 1994

A new method for the quantification of N-(ldeoxy-D-huctas-l-yl)-glycine (DFG) was developed based... more A new method for the quantification of N-(ldeoxy-D-huctas-l-yl)-glycine (DFG) was developed based on isotope dilution fast atom bombardment tandem mass spectrometry using '3C-laheUed DFG as an internal standard. This method, which requires neither derivatization nor clean-up of the samples, was used to study the degradation of DFG under different conditions (time and pH). It was found that the decomposition of DFG at 90°C was favoured at pH 7 compared to pH 6. The higher stability of DFG at pH 6 was due to 1,2-enolization leading to the relatively stable 3deoxglucosone

Research paper thumbnail of Effect of compounds affecting ABCA1 expression and CETP activity on the HDL pathway involved in intestinal absorption of lutein and zeaxanthin

Lipids, 2014

The antioxidant xanthophylls lutein and zeaxanthin are absorbed from the diet in a process involv... more The antioxidant xanthophylls lutein and zeaxanthin are absorbed from the diet in a process involving lipoprotein formation. Selective mechanisms exist for their intestinal uptake and tissue-selective distribution, but these are poorly understood. We investigated the role of high-density lipoprotein (HDL), apolipoprotein (apo) A1 and ATP-binding cassette transporter (ABC) A1 in intestinal uptake of lutein in a human polarized intestinal cell culture and a hamster model. Animals received dietary lutein and zeaxanthin and either a liver X receptor (LXR) agonist or statin, which up- or down-regulate intestinal ABCA1 expression, respectively. The role of HDL was studied following treatment with the cholesteryl ester transfer protein (CETP) modulator dalcetrapib or the CETP inhibitor anacetrapib. In vitro, intestinal ABCA1 at the basolateral surface of enterocytes transferred lutein and zeaxanthin to apoA1, not to mature HDL. In hamsters, plasma lutein and zeaxanthin levels were markedly ...

Research paper thumbnail of Mechanism of gas-phase aldose-ketose isomerization: A study using tandem mass spectrometry and theoretical calculations

Journal of the American Society for Mass Spectrometry, 1993

Fast-atom bombardment tandem mass spectcometcy and the semiempirical molecular orbital method wer... more Fast-atom bombardment tandem mass spectcometcy and the semiempirical molecular orbital method were used to investigate the mechanism of gas-phase aldose-ketose isomerization process in lithiated 1,3 linked disaccharide isomers. Both the 1,3 hydrogen shift and hydride transfer mechanisms were investigated. Our experimental and theoretical calculations support the latter. The hydride transfer mechanism in these lithium-coordinated systems is similar to the xylose isomecase catalyzed aldoseeketose isomerization. CJ Am SOC Muss Spectrom 1993, 4, 943-948)

Research paper thumbnail of Differential regulation of bile acid and cholesterol metabolism by the farnesoid X receptor in Ldlr -/- mice versus hamsters

The Journal of Lipid Research, 2013

Modulating bile acid synthesis has long been considered a good strategy by which to improve chole... more Modulating bile acid synthesis has long been considered a good strategy by which to improve cholesterol homeostasis in humans. The farnesoid X receptor (FXR), the key regulator of bile acid synthesis, was, therefore, identified as an interesting target for drug discovery. We compared the effect of four, structurally unrelated, synthetic FXR agonists in two fat-fed rodent species and observed that the three most potent and selective agonists decreased plasma cholesterol in LDL receptor-deficient (Ldlr (-/-)) mice, but none did so in hamsters. Detailed investigation revealed increases in the expression of small heterodimer partner (Shp) in their livers and of intestinal fibroblast growth factor 15 or 19 (Fgf15/19) in mice only. Cyp7a1 expression and fecal bile acid (BA) excretion were strongly reduced in mice and hamsters by all four FXR agonists, whereas bile acid pool sizes were reduced in both species by all but the X-Ceptor compound in hamsters. In Ldlr (-/-) mice, the predominant bile acid changed from cholate to the more hydrophilic β-muricholate due to a strong repression of Cyp8b1 and increase in Cyp3a11 expression. However, FXR agonists caused only minor changes in the expression of Cyp8b1 and in bile acid profiles in hamsters. In summary, FXR agonist-induced decreases in bile acid pool size and lipophilicity and in cholesterol absorption and synthesis could explain the decreased plasma cholesterol in Ldlr (-/-) mice. In hamsters, FXR agonists reduced bile acid pool size to a smaller extent with minor changes in bile acid profile and reductions in sterol absorption, and consequently, plasma cholesterol was unchanged.

Research paper thumbnail of Effect of Dalcetrapib and Torcetrapib on Noncholesterol Markers of Cholesterol Homeostasis in the Hamster

Journal of Clinical Lipidology, 2011

Research paper thumbnail of A new matrix for fast-atom bombardment analysis of corrins

Rapid Communications in Mass Spectrometry, 1991

2,3-dihydroxypropyl benzyl ether, a glycerol derivative, is a suitable matrix for fast-atom bomba... more 2,3-dihydroxypropyl benzyl ether, a glycerol derivative, is a suitable matrix for fast-atom bombardment analysis. It has been shown to be superior to glycerol and thioglycerol for the detection of molecular ions of cobyrates.

Research paper thumbnail of Effect of Dalcetrapib and Torcetrapib on Noncholesterol Markers of Cholesterol Homeostasis in the Hamster

Journal of Clinical Lipidology, 2011

Results: Fifty-eight patients were randomized (39MIPO, 19 PBO) at 26 clinical centers in 6 countr... more Results: Fifty-eight patients were randomized (39MIPO, 19 PBO) at 26 clinical centers in 6 countries. Forty-five (78%) patients completed the treatment period. Twelve (31%) MIPO and 1 (5%) PBO patient(s) withdrew (8 of the MIPO and the 1 PBO withdrawals were caused by an adverse event [AE]). LDL-C was reduced by 36% from a mean baseline level of 276 mg/dL in the MIPO group vs. an increase of 13% from a BL of 249 mg/dL in the PBO group (p , 0.001). This represents a 101 mg/dL mean reduction of LDL-C in theMIPOgroup. Similarly,MIPOproduced highly significant (P , .001) reductions in other atherogenic lipoproteins, eg, ApoB and Lp(a), there was no change in HDL-C. The most common on-treatment AEs were injection site reactions (90%MIPO, 32% PBO) and flu-like symptoms (46% MIPO, 21% PBO). Six (15%) MIPO patients and no PBO patients had ALT 3!ULNonconsecutivemeasuresatleast7daysapart.OneMIPOpatienthadatransientALT3!ULN on consecutive measures at least 7 days apart. One MIPO patient had a transient ALT 3!ULNonconsecutivemeasuresatleast7daysapart.OneMIPOpatienthadatransientALT10! ULN. ALT elevations were not associated with clinically significant increases in bilirubin. Conclusions: MIPO treatment significantly reduced LDL-C and ApoB in patients with severe hypercholesterolemia. The data support the potential utility of MIPO as a pharmacologic option for additional LDL C lowering in patients with heterozygous hypercholesterolemia not adequately controlled under existing LLTs.

Research paper thumbnail of Modeling the Effects of Severe Metabolic Disease by Genome Editing of hPSC-Derived Endothelial Cells Reveals an Inflammatory Phenotype

International Journal of Molecular Sciences

The kinase AKT2 (PKB) is an important mediator of insulin signaling, for which loss-of-function k... more The kinase AKT2 (PKB) is an important mediator of insulin signaling, for which loss-of-function knockout (KO) mutants lead to early onset diabetes mellitus, and dominant active mutations lead to early development of obesity and endothelial cell (EC) dysfunction. To model EC dysfunction, we used edited human pluripotent stem cells (hPSCs) that carried either a homozygous deletion of AKT2 (AKT2 KO) or a dominant active mutation (AKT2 E17K), which, along with the parental wild type (WT), were differentiated into ECs. Profiling of EC lines indicated an increase in proinflammatory and a reduction in anti-inflammatory fatty acids, an increase in inflammatory chemokines in cell supernatants, increased expression of proinflammatory genes, and increased binding to the EC monolayer in a functional leukocyte adhesion assay for both AKT2 KO and AKT2 E17K. Collectively, these findings suggest that vascular endothelial inflammation that results from dysregulated insulin signaling (homeostasis) ma...

Research paper thumbnail of How Female Mice Attract Males: A Urinary Volatile Amine Activates a Trace Amine-Associated Receptor That Induces Male Sexual Interest

Frontiers in pharmacology, 2018

Individuals of many species rely on odors to communicate, find breeding partners, locate resource... more Individuals of many species rely on odors to communicate, find breeding partners, locate resources and sense dangers. In vertebrates, odorants are detected by chemosensory receptors of the olfactory system. One class of these receptors, the trace amine-associated receptors (TAARs), was recently suggested to mediate male sexual interest and mate choice. Here we tested this hypothesis in mice by generating a cluster deletion mouse () lacking all TAARs expressed in the olfactory epithelium, and evaluating transduction pathways from odorants to TAARs, neural activity and behaviors reflecting sexual interest. We found that a urinary volatile amine, isobutylamine (IBA), was a potent ligand for TAAR3 (but not TAAR1, 4, 5, and 6). When males were exposed to IBA, brain regions associated with sexual behaviors were less active in than in wild type males. Accordingly, males spent less time sniffing both the urine of females and pure IBA than wild type males. This is the first demonstration of ...

Research paper thumbnail of Lewy pathology in Parkinson's disease consists of a crowded organellar membranous medley

Parkinson's disease, the most common age-related movement disorder, is a progressive neurodeg... more Parkinson's disease, the most common age-related movement disorder, is a progressive neurodegenerative disease with unclear etiology. Key neuropathological hallmarks are Lewy bodies and Lewy neurites, which are neuronal inclusions that are immunopositive for the protein alpha-synuclein. In-depth ultrastructural analysis of Lewy pathology is key to understanding pathogenesis and progression of the disease. Using correlative light and electron microscopy on postmortem brain tissue of Parkinson's patients, we discovered a crowded membranous medley of vesicular structures, dysmorphic mitochondria and disrupted cytoskeletal elements in Lewy bodies and Lewy neurites, rather than the widely expected proteinacious filaments. The collapse and crowding of central organellar components was confirmed by stimulated emission-depletion microscopy, and chemical and optical imaging. A high lipid content was confirmed by lipidomics. The findings indicate ill-defined subcellular protein-lipid ...

Research paper thumbnail of Abstract LB-085: RG70099: A novel, highly potent dual IDO1/TDO inhibitor to reverse metabolic suppression of immune cells in the tumor micro-environment

Research paper thumbnail of Procédé pour la préparation d'acide cyclohexanecarboxylique

Research paper thumbnail of Identification and structure of a family of syringolin variants : Unusual cyclic peptides from Pseudomonas syringae pv. syringae that elicit defense responses in rice

Microbiological Research, May 1, 1999

Pseudomonas syringae pv. syringae is recognized by the non-host plant Oryza sativa which reacts w... more Pseudomonas syringae pv. syringae is recognized by the non-host plant Oryza sativa which reacts with defense responses leading to induced resistance towards the rice blast fungus Pyricularia oryzae. We have previously shown that syring olin, a novel and unusual peptide secreted by P. syringae pv. syringae under appropriate conditions, is one of the molecular determinants by which rice plants can perceive the non-host pathogen. Here we show that syringolin is a member of a family of related compounds. We have isolated syringolin variants B to F and determined their structure using mass and NMR spectroscopic methods. These variants, which differ from each other by various modifications, are all able to induce defense responses upon application onto rice leaves.

Research paper thumbnail of Process for the preparation of cyclohexanecarboxylic acid derivatives

Research paper thumbnail of Determination of taurine metabolism by measurement of 15N-enriched taurine in cat urine by gas chromatography—mass spectrometry

Journal of Chromatography B: Biomedical Sciences and Applications, 1993

To understand the biological function of taurine, a study of taurine kinetics in the cat was unde... more To understand the biological function of taurine, a study of taurine kinetics in the cat was undertaken. This paper describes a method developed for the accurate determination of XSN-taurine enrichment in cat urine by gas chromatography-mass spectrometry. 15N-Taurine was given to six animals as an oral bolus dose of 20 mg/kg body weight, and the urine was pooled on a daily basis. The hydrolysed or non-hydrolysed urine samples (for total and free taurine, respectively) were directly derivatized without further purification. The N-pentafluorobenzoyl din -butyl amide derivative obtained was analysed, and the fragment [M-(di-n-butyl amide)] +, carrier of the labelled nitrogen atom, was selectively recorded at m/z 302 (14N-taurine) and m/z 303 (15N.taurine)" Calibration curves prepared in hydrolysed and non-hydrolysed urine samples spiked with 15N.taurin e gave similar slopes to the calibration curve prepared in water. The average coefficient of variation observed for the mole percent excess in the non-hydrolysed samples was 1.22% (n = 92) and for the hydrolysed urine 1.00% (n = 98). There was no significant difference between free and total taurine enrichment. The half-life of taurine in cat body was found to be 29.3 4-2.9 h and 35.0 + 1.4 h for free and total taurine, respectively (non-significant). The taurine body pool, calculated by extrapolation of the curve to zero time, had a value of 137 4-22 ng/kg and 157 4-I 1 mg/kg for free and total taurine, respectively.

Research paper thumbnail of First preparative biocatalytic hydrolysis and S-methylation of cyclic trithiocarbonates

Tetrahedron, 2002

ÐThe biocatalytic degradation of a cyclic trithiocarbonate, 6-amino-5-methoxycarbonyl-thieno[2,3-... more ÐThe biocatalytic degradation of a cyclic trithiocarbonate, 6-amino-5-methoxycarbonyl-thieno[2,3-d]-1,3-dithiole-2-thione 1, is reported. The product of the hydrolysis of the ®ve-membered ring by Pseudomonas chlororaphis ATCC 9447 oxidatively dimerized to form the tetrathiocin derivative 2. Furthermore, we performed the ®rst preparative biocatalytic methylation of an unnatural compound employing Emericella unguis ATCC 10032 by cleaving the dithiole ring 1 followed by methylation of both thiol groups to form the methylated product 4 in 64% isolated yield.

Research paper thumbnail of Determination of taurine metabolism by measurement of 15 N-enriched taurine in cat urine by gas chromatography—mass spectrometry

To understand the biological function of taurine, a study of taurine kinetics in the cat was unde... more To understand the biological function of taurine, a study of taurine kinetics in the cat was undertaken. This paper describes a method developed for the accurate determination of XSN-taurine enrichment in cat urine by gas chromatography-mass spectrometry. 15N-Taurine was given to six animals as an oral bolus dose of 20 mg/kg body weight, and the urine was pooled on a daily basis. The hydrolysed or non-hydrolysed urine samples (for total and free taurine, respectively) were directly derivatized without further purification. The N-pentafluorobenzoyl din -butyl amide derivative obtained was analysed, and the fragment [M-(di-n-butyl amide)] +, carrier of the labelled nitrogen atom, was selectively recorded at m/z 302 (14N-taurine) and m/z 303 (15N.taurine)" Calibration curves prepared in hydrolysed and non-hydrolysed urine samples spiked with 15N.taurin e gave similar slopes to the calibration curve prepared in water. The average coefficient of variation observed for the mole percent excess in the non-hydrolysed samples was 1.22% (n = 92) and for the hydrolysed urine 1.00% (n = 98). There was no significant difference between free and total taurine enrichment. The half-life of taurine in cat body was found to be 29.3 4-2.9 h and 35.0 + 1.4 h for free and total taurine, respectively (non-significant). The taurine body pool, calculated by extrapolation of the curve to zero time, had a value of 137 4-22 ng/kg and 157 4-I 1 mg/kg for free and total taurine, respectively.

Research paper thumbnail of 198 Effect of Dalcetrapib on Non-Cholesterol Markers of Cholesterol Homeostasis in Healthy Subjects

Background: Apolipoprotein A-I (apoA-I) induction represents a novel therapeutic approach to prom... more Background: Apolipoprotein A-I (apoA-I) induction represents a novel therapeutic approach to promoting high-density lipoprotein (HDL) functionality. The relationship between changes in conventional HDL measures and particle markers with apoA-I induction has not been investigated. Methods: The ASSERT study evaluated early biochemical changes with increasing doses of an apoA-I inducer (RVX-208 100-300 mg daily) for 12 weeks in statin-treated patients with stable coronary artery disease. Changes in HDL particle markers on 2D gel electrophoresis and NMR spectroscopy were characterized. Results: Administration of RVX-208 was associated with dose-dependent increases in levels of apoA-I (0.1−5.6%), HDL cholesterol (3.2−8.3%), large HDL particles (11.1-21.1%) on NMR and larger a1 particles (3.7−8.8%), but no change in small, lipid-deplete preb1 particles on 2D gel analysis. Significant correlations were observed between changes in HDL cholesterol and changes in total HDL particles (r = 0.44, p < 0.0001), large HDL (r = 0.55, p < 0.0001), small HDL (r = 0.22, p = 0.0002), preb1 (r = 0.16, p = 0.009) and a1 (r = 0.58, p < 0.0001) particles. Patients in the highest quartile increase in HDL cholesterol (>14%) demonstrated greater increases in HDL particle concentration (+10.1 vs −3.1%, p < 0.001) and size (+2.3 vs 0%, p < 0.001), large HDL particles (+46.9 vs −9.1%, p < 0.001), preb1 particles (+6.6 vs −5.1%, p = 0.04) and a1 particles (+29.5 vs −20.9%, p < 0.001) compared with lowest quartile. Conclusion: While changes in larger HDL particles predominate with apoA-I induction, patients with the most robust lipid response demonstrated increases in both small and large HDL particles. The functional consequences of these changes on atherosclerotic plaque remain to be determined.

Research paper thumbnail of Gas-phase dissociation mechanisms of dilithiated disaccharides: tandem mass spectrometry and semiempirical calculations

J Org Chem, 1992

Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilith... more Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilithiated disaccharides is used to differentiate the linkage position of three isomeric disaccharides. The mechanisms of dissociation proposed are based on the mass spectrometry, experimental data, and semiempirical calculations, the latter of which provide information on the stability of the deprotonated dilithiated precursor, (M + 2Li -H)+. Tandem mass spectrometry experiments indicate that, as in the case of monolithiated disaccharides, reducing ring opening occurs followed by two-, three-, and four-carbon chain neutral losses. Semiempirical calculations support the experimental data which suggest that one lithium is tetracoordinate between the two sugar rings, while the second lithium is dicoordinate forming a lithium alkoxide with one of the deprotonated hydroxyl groups of the reducing ring.

Research paper thumbnail of Gas-phase dissociation mechanisms of dilithiated disaccharides: tandem mass spectrometry and semiempirical calculations

The Journal of Organic Chemistry, 1992

Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilith... more Fast atom bombardment ionization followed by tandem mass spectrometry of 'Boand 2H-labeled dilithiated disaccharides is used to differentiate the linkage position of three isomeric disaccharides. The mechanisms of dissociation proposed are based on the mass spectrometry, experimental data, and semiempirical calculations, the latter of which provide information on the stability of the deprotonated dilithiated precursor, (M + 2Li -H)+. Tandem mass spectrometry experiments indicate that, as in the case of monolithiated disaccharides, reducing ring opening occurs followed by two-, three-, and four-carbon chain neutral losses. Semiempirical calculations support the experimental data which suggest that one lithium is tetracoordinate between the two sugar rings, while the second lithium is dicoordinate forming a lithium alkoxide with one of the deprotonated hydroxyl groups of the reducing ring.

Research paper thumbnail of Study on the decomposition of the amadori compoundN-(1-deoxy-D-fructos-1-y1)-glycine in model systems: Quantification by fast atom bombardment tandem mass spectrometry

Biological Mass Spectrometry, 1994

A new method for the quantification of N-(ldeoxy-D-huctas-l-yl)-glycine (DFG) was developed based... more A new method for the quantification of N-(ldeoxy-D-huctas-l-yl)-glycine (DFG) was developed based on isotope dilution fast atom bombardment tandem mass spectrometry using '3C-laheUed DFG as an internal standard. This method, which requires neither derivatization nor clean-up of the samples, was used to study the degradation of DFG under different conditions (time and pH). It was found that the decomposition of DFG at 90°C was favoured at pH 7 compared to pH 6. The higher stability of DFG at pH 6 was due to 1,2-enolization leading to the relatively stable 3deoxglucosone

Research paper thumbnail of Effect of compounds affecting ABCA1 expression and CETP activity on the HDL pathway involved in intestinal absorption of lutein and zeaxanthin

Lipids, 2014

The antioxidant xanthophylls lutein and zeaxanthin are absorbed from the diet in a process involv... more The antioxidant xanthophylls lutein and zeaxanthin are absorbed from the diet in a process involving lipoprotein formation. Selective mechanisms exist for their intestinal uptake and tissue-selective distribution, but these are poorly understood. We investigated the role of high-density lipoprotein (HDL), apolipoprotein (apo) A1 and ATP-binding cassette transporter (ABC) A1 in intestinal uptake of lutein in a human polarized intestinal cell culture and a hamster model. Animals received dietary lutein and zeaxanthin and either a liver X receptor (LXR) agonist or statin, which up- or down-regulate intestinal ABCA1 expression, respectively. The role of HDL was studied following treatment with the cholesteryl ester transfer protein (CETP) modulator dalcetrapib or the CETP inhibitor anacetrapib. In vitro, intestinal ABCA1 at the basolateral surface of enterocytes transferred lutein and zeaxanthin to apoA1, not to mature HDL. In hamsters, plasma lutein and zeaxanthin levels were markedly ...

Research paper thumbnail of Mechanism of gas-phase aldose-ketose isomerization: A study using tandem mass spectrometry and theoretical calculations

Journal of the American Society for Mass Spectrometry, 1993

Fast-atom bombardment tandem mass spectcometcy and the semiempirical molecular orbital method wer... more Fast-atom bombardment tandem mass spectcometcy and the semiempirical molecular orbital method were used to investigate the mechanism of gas-phase aldose-ketose isomerization process in lithiated 1,3 linked disaccharide isomers. Both the 1,3 hydrogen shift and hydride transfer mechanisms were investigated. Our experimental and theoretical calculations support the latter. The hydride transfer mechanism in these lithium-coordinated systems is similar to the xylose isomecase catalyzed aldoseeketose isomerization. CJ Am SOC Muss Spectrom 1993, 4, 943-948)

Research paper thumbnail of Differential regulation of bile acid and cholesterol metabolism by the farnesoid X receptor in Ldlr -/- mice versus hamsters

The Journal of Lipid Research, 2013

Modulating bile acid synthesis has long been considered a good strategy by which to improve chole... more Modulating bile acid synthesis has long been considered a good strategy by which to improve cholesterol homeostasis in humans. The farnesoid X receptor (FXR), the key regulator of bile acid synthesis, was, therefore, identified as an interesting target for drug discovery. We compared the effect of four, structurally unrelated, synthetic FXR agonists in two fat-fed rodent species and observed that the three most potent and selective agonists decreased plasma cholesterol in LDL receptor-deficient (Ldlr (-/-)) mice, but none did so in hamsters. Detailed investigation revealed increases in the expression of small heterodimer partner (Shp) in their livers and of intestinal fibroblast growth factor 15 or 19 (Fgf15/19) in mice only. Cyp7a1 expression and fecal bile acid (BA) excretion were strongly reduced in mice and hamsters by all four FXR agonists, whereas bile acid pool sizes were reduced in both species by all but the X-Ceptor compound in hamsters. In Ldlr (-/-) mice, the predominant bile acid changed from cholate to the more hydrophilic β-muricholate due to a strong repression of Cyp8b1 and increase in Cyp3a11 expression. However, FXR agonists caused only minor changes in the expression of Cyp8b1 and in bile acid profiles in hamsters. In summary, FXR agonist-induced decreases in bile acid pool size and lipophilicity and in cholesterol absorption and synthesis could explain the decreased plasma cholesterol in Ldlr (-/-) mice. In hamsters, FXR agonists reduced bile acid pool size to a smaller extent with minor changes in bile acid profile and reductions in sterol absorption, and consequently, plasma cholesterol was unchanged.

Research paper thumbnail of Effect of Dalcetrapib and Torcetrapib on Noncholesterol Markers of Cholesterol Homeostasis in the Hamster

Journal of Clinical Lipidology, 2011