Perturbation and resilience of the gut microbiome up to 3 months after β-lactams exposure in healthy volunteers suggest an important role of microbial β-lactamases

BACKGROUND

Antibiotics notoriously perturb the gut microbiota. We treated healthy volunteers either with cefotaxime or ceftriaxone for 3 days, and collected in each subject 12 faecal samples up to day 90. Using untargeted and targeted phenotypic and genotypic approaches, we studied the changes in the bacterial, phage and fungal components of the microbiota as well as the metabolome and the β-lactamase activity of the stools. This allowed assessing their degrees of perturbation and resilience.

RESULTS

While only two subjects had detectable concentrations of antibiotics in their faeces, suggesting important antibiotic degradation in the gut, the intravenous treatment perturbed very significantly the bacterial and phage microbiota, as well as the composition of the metabolome. In contrast, treatment impact was relatively low on the fungal microbiota. At the end of the surveillance period, we found evidence of resilience across the gut system since most components returned to a state like the initial one, even if the structure of the bacterial microbiota changed and the dynamics of the different components over time were rarely correlated. The observed richness of the antibiotic resistance genes repertoire was significantly reduced up to day 30, while a significant increase in the relative abundance of β-lactamase encoding genes was observed up to day 10, consistent with a concomitant increase in the β-lactamase activity of the microbiota. The level of β-lactamase activity at baseline was positively associated with the resilience of the metabolome content of the stools.

CONCLUSIONS

In healthy adults, antibiotics perturb many components of the microbiota, which return close to the baseline state within 30 days. These data suggest an important role of endogenous β-lactamase-producing anaerobes in protecting the functions of the microbiota by de-activating the antibiotics reaching the colon. Video Abstract.

Left atrial strain: A memory of the severity of atrial myocardial stress in atrial fibrillation

BACKGROUND

Left atrial (LA) strain is a simple marker of LA function. The aim of the study was to evaluate the determinants of atrial cardiomyopathy in AF.

METHODS

In this pilot study, we prospectively evaluated clinical, biological, metabolomic and echocardiographic parameters for 85 consecutive patients hospitalized for atrial fibrillation (AF) with restoration of sinus rhythm at 6 months. Eighty-one patients with an analysable LA strain at 6 months were divided into groups according to median reservoir strain:<23.3% (n=40) versus≥23.3% (n=41).

RESULTS

Compared to patients with the highest LA strain, patients with lowest LA strain had multiple differences at admission: clinical (older age; more frequent history of AF; more patterns of persistent AF); biological (higher fasting blood glucose levels, glycated haemoglobin, high-sensitivity C-reactive protein, and urea; lower glomerular filtration rate); metabolomic (higher levels of kynurenine, kynurenine/tryptophan, and urea/creatinine; lower levels of arginine and methionine/methionine sulfoxide); and echocardiographic (higher two-dimensional end-systolic LA volume [LAV] indexes; higher three-dimensional end-systolic and end-diastolic LAV and right atrial volume indexes; lower LA and right atrial emptying fractions and three-dimensional right ventricular ejection fraction) (all P<0.05). Area under the receiver operating characteristic curve to predict LA strain alteration at 6 months was highest for a combined score including clinical, biological, metabolomic and echocardiographic variables at admission (area under the receiver operating characteristic curve 0.871; P<0.0001).

CONCLUSIONS

LA reservoir strain could be a memory of initial atrial myocardial stress in AF. It can be predicted using a combination of clinical, biological, metabolomic and echocardiographic admission variables.

Impaired metabolism predicts coronary artery calcification in women with systemic lupus erythematosus

BACKGROUND

Patients with systemic lupus erythematosus (SLE) exhibit a high risk for cardiovascular diseases (CVD) which is not fully explained by the classical Framingham risk factors. SLE is characterized by major metabolic alterations which can contribute to the elevated prevalence of CVD.

METHODS

A comprehensive analysis of the circulating metabolome and lipidome was conducted in a large cohort of 211 women with SLE who underwent a multi-detector computed tomography scan for quantification of coronary artery calcium (CAC), a robust predictor of coronary heart disease (CHD).

FINDINGS

Beyond traditional risk factors, including age and hypertension, disease activity and duration were independent risk factors for developing CAC in women with SLE. The presence of coronary calcium was associated with major alterations of circulating lipidome dominated by an elevated abundance of ceramides with very long chain fatty acids. Alterations in multiple metabolic pathways, including purine, arginine and proline metabolism, and microbiota-derived metabolites, were also associated with CAC in women with SLE. Logistic regression with bootstrapping of lipidomic and metabolomic variables were used to develop prognostic scores. Strikingly, combining metabolic and lipidomic variables with clinical and biological parameters markedly improved the prediction (area under the curve: 0.887, p < 0.001) of the presence of coronary calcium in women with SLE.

INTERPRETATION

The present study uncovers the contribution of disturbed metabolism to the presence of coronary artery calcium and the associated risk of CHD in SLE. Identification of novel lipid and metabolite biomarkers may help stratifying patients for reducing CVD morbidity and mortality in SLE.

FUNDING

INSERM and Sorbonne Université.

Short-chain fatty acids levels in human milk are not affected by holder pasteurization and high hydrostatic pressure processing

Sterilized donor milk (DM) is frequently used for feeding preterm infants. To date, the effect of different modes of DM sterilization on short-chain fatty acids (SCFAs) remains unknown. We aimed to quantify SCFAs in DM samples after two types of milk sterilization: the Holder pasteurization (HoP) and a high hydrostatic pressure (HP) processing. Eight pooled DM samples were sterilized by HoP (62.5°C for 30 min) or processed by HP (350 MPa at 38°C). Raw DM was used as control. Six SCFAs were quantified by gas chromatography/mass spectrometry. Compared to raw milk, both HoP and HP treatment did not significantly modulate the concentration of acetate, butyrate, propionate and isovalerate in DM. Valerate and isobutyrate were undetectable in DM samples. In conclusion, both HoP and HP processing preserved milk SCFAs at their initial levels in raw human milk.

Impacts of a high-fat diet on the metabolic profile and the phenotype of atrial myocardium in mice

AIMS

Obesity, diabetes, and metabolic syndromes are risk factors of atrial fibrillation (AF). We tested the hypothesis that metabolic disorders have a direct impact on the atria favouring the formation of the substrate of AF.

METHODS AND RESULTS

Untargeted metabolomic and lipidomic analysis was used to investigate the consequences of a prolonged high-fat diet (HFD) on mouse atria. Atrial properties were characterized by measuring mitochondria respiration in saponin-permeabilized trabeculae, by recording action potential (AP) with glass microelectrodes in trabeculae and ionic currents in myocytes using the perforated configuration of patch clamp technique and by several immuno-histological and biochemical approaches. After 16 weeks of HFD, obesogenic mice showed a vulnerability to AF. The atrial myocardium acquired an adipogenic and inflammatory phenotypes. Metabolomic and lipidomic analysis revealed a profound transformation of atrial energy metabolism with a predominance of long-chain lipid accumulation and beta-oxidation activation in the obese mice. Mitochondria respiration showed an increased use of palmitoyl-CoA as energy substrate. APs were short duration and sensitive to the K-ATP-dependent channel inhibitor, whereas K-ATP current was enhanced in isolated atrial myocytes of obese mouse.

CONCLUSION

HFD transforms energy metabolism, causes fat accumulation, and induces electrical remodelling of the atrial myocardium of mice that become vulnerable to AF.

Tolerogenic Dendritic Cells Shape a Transmissible Gut Microbiota That Protects From Metabolic Diseases

Excess chronic contact between microbial motifs and intestinal immune cells is known to trigger a low-grade inflammation involved in many pathologies such as obesity and diabetes. The important skewing of intestinal adaptive immunity in the context of diet-induced obesity (DIO) is well described, but how dendritic cells (DCs) participate in these changes is still poorly documented. To address this question, we challenged transgenic mice with enhanced DC life span and immunogenicity (DC^hBcl-2 mice) with a high-fat diet. Those mice display resistance to DIO and metabolic alterations. The DIO-resistant phenotype is associated with healthier parameters of intestinal barrier function and lower intestinal inflammation. DC^hBcl-2 DIO-resistant mice demonstrate a particular increase in tolerogenic DC numbers and function, which is associated with strong intestinal IgA, T helper 17, and regulatory T-cell immune responses. Microbiota composition and function analyses reveal that the DC^hBcl-2 mice microbiota is characterized by lower immunogenicity and an enhanced butyrate production. Cohousing experiments and fecal microbial transplantations are sufficient to transfer the DIO resistance status to wild-type mice, demonstrating that maintenance of DCs' tolerogenic ability sustains a microbiota able to drive DIO resistance. The tolerogenic function of DCs is revealed as a new potent target in metabolic disease management.

Serum Tryptophan-Derived Quinolinate and Indole-3-Acetate Are Associated With Carotid Intima-Media Thickness and its Evolution in HIV-Infected Treated Adults

Background

HIV-infected individuals undergoing effective antiretroviral therapy (ART) present an increased risk of atherosclerotic cardiovascular disease. We identified serum metabolites associated with carotid intima-media thickness (c-IMT) and its evolution.

Methods

One hundred forty-three hydrophilic serum metabolites were measured by ultraperformance liquid chromatography coupled with high-resolution mass spectrometry in 49 HIV+ ART+, 48 HIV+ ART-naïve and 50 HIV-negative, age-matched, never-smoking male triads. Metabolites differentially altered between groups ("features") were defined as having a Benjamini-Hochberg-adjusted P value <.05 from a t test and >0.25 log₂ absolute mean fold change in metabolite levels. c-IMT was measured across 12 sites at inclusion in all individuals and at the carotid artery (cca) after a median of 5.1 years in 32 HIV+ ART+ individuals. The difference in c-IMT (cross-sectional analysis) and slope of cca-IMT regression/progression per year (longitudinal analysis) for each log₁₀ (area) increase in metabolite level were estimated with linear regression.

Results

Compared with HIV-, metabolite features of HIV+ ART+ were increased N6,N6,N6-trimethyl-L-lysine and decreased ferulate and 5-hydroxy-L-tryptophan, whereas features of HIV+ ART-naïve were increased malate, kynurenine, 2-oxoglutarate, and indole-3-acetate and decreased succinate and 5-hydroxy-L-tryptophan. In HIV+ ART+ individuals, quinolinate and/or indole-3-acetate were positively associated with c-IMT (P < .03), cca-IMT (P < .03), and cca-IMT progression (P < .008). These associations were not observed in HIV+ ART-naïve or HIV-negative individuals. In HIV+ ART+ individuals, the metabolites xanthosine and uridine, from nucleotide metabolism, and g-butyrobetaine, from lysine/dietary choline degradation, were also positively or negatively associated with c-IMT and/or cca-IMT (all P < .01), but not its evolution.

Conclusions

In these highly selected HIV-positive ART-controlled males, 2 novel metabolites derived from tryptophan catabolism, indole-3-acetate and quinolinate, were associated with c-IMT and its progression.

The intestinal microbiota regulates host cholesterol homeostasis

BACKGROUND

Management of blood cholesterol is a major focus of efforts to prevent cardiovascular diseases. The objective of this study was to investigate how the gut microbiota affects host cholesterol homeostasis at the organism scale.

RESULTS

We depleted the intestinal microbiota of hypercholesterolemic female Apoe^-/- mice using broad-spectrum antibiotics. Measurement of plasma cholesterol levels as well as cholesterol synthesis and fluxes by complementary approaches showed that the intestinal microbiota strongly regulates plasma cholesterol level, hepatic cholesterol synthesis, and enterohepatic circulation. Moreover, transplant of the microbiota from humans harboring elevated plasma cholesterol levels to recipient mice induced a phenotype of high plasma cholesterol levels in association with a low hepatic cholesterol synthesis and high intestinal absorption pattern. Recipient mice phenotypes correlated with several specific bacterial phylotypes affiliated to Betaproteobacteria, Alistipes, Bacteroides, and Barnesiella taxa.

CONCLUSIONS

These results indicate that the intestinal microbiota determines the circulating cholesterol level and may thus represent a novel therapeutic target in the management of dyslipidemia and cardiovascular diseases.

P3483Diet governs metabolic and electrical properties of the atrial myocardium in mice

Background

Obesity is associated with an increased risk of atrial fibrillation. This epidemiologic observation may not only be due to shared co-morbidities but also from direct impacts of metabolic disorders on myocardium Here, we examined the impact of high fat diet (HFD) induced obesity on atrial properties in mice.

Methods

Eight weeks old C57Bl/6J mice were subjected to 2 or 4 months of HFD (60% fat) or normal diet (ND, 4% fat). Rapid burst atrial pacing were delivered using a trans-esophageal probe to induced AF in anesthetized animals. Action potential (AP) were recorded in left atrial trabeculae using glass microelectrode technique. Potassium currents were recorded in isolated atrial myocytes using the whole cell or perforated patch clamp configurations. Metabolomic and lipidomic analysis were performed on whole left atria. Mitochondrial respiration was studied in situ in saponin-permeabilized atrial muscle fibres using a Clarke electrode and oxygen consumption was measured after successive addition of ADP (2 mM), malate (4 mM), palmitoyl-CoA and carnitine (pCoA-Ca) (100 μM and 2 mM), pyruvate (1 mM), glutamate (10 mM), succinate (15 mM), amytal (1 mM) and tetramethyl-paraphenylenediamine (TMPD)/ascorbate (0.5/0.5 mM).

Results

HFD mice showed a higher atrial vulnerability to AF as indicated by longer AF episodes compared to ND mice. APs were shorter in HFD versus ND mice (AP duration measured at 90% of repolarization: 47.9±2.4 msec in HFD vs 58.2±1.4 msec in ND, P<0.001 after 2 months of HFD) and more sensitive to the K ATP channel blocker, glibenclamide. In perforated but not whole cell, patch clamped atrial myocytes, the K-ATP component of the potassium current was enhanced in HFD mice (at +70 mV: 0.41±0.12 pA/pF in HFD vs 0.13±0.08 pA/pF in ND, P<0.05). Metabolomic analysis indicated an increased consumption of free fatty acid by the beta-oxidation and an accumulation of long chain fatty acid. Although the mitochondrial respiration measurements showed a trend towards a lower complex IV-driven respiration in HFD mice, no significant difference between ND and HFD was noted regarding complex I and complex II-driven respiration. However, the ability of fatty acids (pCoA-Car) to support mitochondrial respiration was higher in HFD

Conclusions

High fat diet induces a shift from carbon hydrate to a beta oxidation of the atrial myocardium metabolism together with an enhanced use of fatty acids by mitochondria. These metabolic changes could result in an enhanced activity of K-ATP channels and AP shortening that might contribute to AF vulnerability in this clinical setting.

Acknowledgement/Funding

ANR-10-IAHU-05

Multi-omics signature of brain amyloid deposition in asymptomatic individuals at-risk for Alzheimer's disease: The INSIGHT-preAD study

BACKGROUND

One of the biggest challenge in Alzheimer's disease (AD) is to identify pathways and markers of disease prediction easily accessible, for prevention and treatment. Here we analysed blood samples from the INveStIGation of AlzHeimer's predicTors (INSIGHT-preAD) cohort of elderly asymptomatic individuals with and without brain amyloid load.

METHODS

We performed blood RNAseq, and plasma metabolomics and lipidomics using liquid chromatography-mass spectrometry on 48 individuals amyloid positive and 48 amyloid negative (SUVr cut-off of 0·7918). The three data sets were analysed separately using differential gene expression based on negative binomial distribution, non-parametric (Wilcoxon) and parametric (correlation-adjusted Student't) tests. Data integration was conducted using sparse partial least squares-discriminant and principal component analyses. Bootstrap-selected top-ten features from the three data sets were tested for their discriminant power using Receiver Operating Characteristic curve. Longitudinal metabolomic analysis was carried out on a subset of 22 subjects.

FINDINGS

Univariate analyses identified three medium chain fatty acids, 4-nitrophenol and a set of 64 transcripts enriched for inflammation and fatty acid metabolism differentially quantified in amyloid positive and negative subjects. Importantly, the amounts of the three medium chain fatty acids were correlated over time in a subset of 22 subjects (p < 0·05). Multi-omics integrative analyses showed that metabolites efficiently discriminated between subjects according to their amyloid status while lipids did not and transcripts showed trends. Finally, the ten top metabolites and transcripts represented the most discriminant omics features with 99·4% chance prediction for amyloid positivity.

INTERPRETATION

This study suggests a potential blood omics signature for prediction of amyloid positivity in asymptomatic at-risk subjects, allowing for a less invasive, more accessible, and less expensive risk assessment of AD as compared to PET studies or lumbar puncture. FUND: Institut Hospitalo-Universitaire and Institut du Cerveau et de la Moelle Epiniere (IHU-A-ICM), French Ministry of Research, Fondation Alzheimer, Pfizer, and Avid.

A Data Integration Multi-Omics Approach to Study Calorie Restriction-Induced Changes in Insulin Sensitivity

Background: The mechanisms responsible for calorie restriction (CR)-induced improvement in insulin sensitivity (IS) have not been fully elucidated. Greater insight can be achieved through deep biological phenotyping of subjects undergoing CR, and integration of big data. Materials and Methods: An integrative approach was applied to investigate associations between change in IS and factors from host, microbiota, and lifestyle after a 6-week CR period in 27 overweight or obese adults (ClinicalTrials.gov: NCT01314690). Partial least squares regression was used to determine associations of change (week 6 - baseline) between IS markers and lifestyle factors (diet and physical activity), subcutaneous adipose tissue (sAT) gene expression, metabolomics of serum, urine and feces, and gut microbiota composition. ScaleNet, a network learning approach based on spectral consensus strategy (SCS, developed by us) was used for reconstruction of biological networks. Results: A spectrum of variables from lifestyle factors (10 nutrients), gut microbiota (10 metagenomics species), and host multi-omics (metabolic features: 84 from serum, 73 from urine, and 131 from feces; and 257 sAT gene probes) most associated with IS were identified. Biological network reconstruction using SCS, highlighted links between changes in IS, serum branched chain amino acids, sAT genes involved in endoplasmic reticulum stress and ubiquitination, and gut metagenomic species (MGS). Linear regression analysis to model how changes of select variables over the CR period contribute to changes in IS, showed greatest contributions from gut MGS and fiber intake. Conclusion: This work has enhanced previous knowledge on links between host glucose homeostasis, lifestyle factors and the gut microbiota, and has identified potential biomarkers that may be used in future studies to predict and improve individual response to weight-loss interventions. Furthermore, this is the first study showing integration of the wide range of data presented herein, identifying 115 variables of interest with respect to IS from the initial input, consisting of 9,986 variables. Clinical Trial Registration: clinicaltrials.gov (NCT01314690).

Comparative Evaluation of Microbiota Engraftment Following Fecal Microbiota Transfer in Mice Models: Age, Kinetic and Microbial Status Matter

The intestinal microbiota and its functions are intricately interwoven with host physiology. Colonizing rodents with donor microbiota provides insights into host-microbiota interactions characterization and the understanding of disease physiopathology. However, a better assessment of inoculation methods and recipient mouse models is needed. Here, we compare the engraftment at short and long term of genetically obese mice microbiota in germ-free (GF) mice and juvenile and adult specific pathogen free (SPF) mice. We also tested the effects of initial microbiota depletion before microbiota transfer. In the present work, donor microbiota engraftment was better in juvenile SPF mice than in adult SPF mice. In juvenile mice, initial microbiota depletion using laxatives or antibiotics improved donor microbiota engraftment 9 weeks but not 3 weeks after microbiota transfer. Microbiota-depleted juvenile mice performed better than GF mice 3 weeks after the microbiota transfer. However, 9 weeks after transfer, colonized GF mice microbiota had the lowest Unifrac distance to the donor microbiota. Colonized GF mice were also characterized by a chronic alteration in intestinal absorptive function. With these collective results, we show that the use of juvenile mice subjected to initial microbiota depletion constitutes a valid alternative to GF mice in microbiota transfer studies.

Major microbiota dysbiosis in severe obesity: fate after bariatric surgery

OBJECTIVES

Decreased gut microbial gene richness (MGR) and compositional changes are associated with adverse metabolism in overweight or moderate obesity, but lack characterisation in severe obesity. Bariatric surgery (BS) improves metabolism and inflammation in severe obesity and is associated with gut microbiota modifications. Here, we characterised severe obesity-associated dysbiosis (ie, MGR, microbiota composition and functional characteristics) and assessed whether BS would rescue these changes.

DESIGN

Sixty-one severely obese subjects, candidates for adjustable gastric banding (AGB, n=20) or Roux-en-Y-gastric bypass (RYGB, n=41), were enrolled. Twenty-four subjects were followed at 1, 3 and 12 months post-BS. Gut microbiota and serum metabolome were analysed using shotgun metagenomics and liquid chromatography mass spectrometry (LC-MS). Confirmation groups were included.

RESULTS

Low gene richness (LGC) was present in 75% of patients and correlated with increased trunk-fat mass and comorbidities (type 2 diabetes, hypertension and severity). Seventy-eight metagenomic species were altered with LGC, among which 50% were associated with adverse body composition and metabolic phenotypes. Nine serum metabolites (including glutarate, 3-methoxyphenylacetic acid and L-histidine) and functional modules containing protein families involved in their metabolism were strongly associated with low MGR. BS increased MGR 1 year postsurgery, but most RYGB patients remained with low MGR 1 year post-BS, despite greater metabolic improvement than AGB patients.

CONCLUSIONS

We identified major gut microbiota alterations in severe obesity, which include decreased MGR and related functional pathways linked with metabolic deteriorations. The lack of full rescue post-BS calls for additional strategies to improve the gut microbiota ecosystem and microbiome-host interactions in severe obesity.

TRIAL REGISTRATION NUMBER

NCT01454232.

Targeted versus untargeted omics - the CAFSA story

BACKGROUND

In 2009, untargeted metabolomics led to the delineation of a new clinico-biological entity called cerebellar ataxia with elevated cerebrospinal free sialic acid, or CAFSA. In order to elucidate CAFSA, we applied sequentially targeted and untargeted omic approaches.

METHODS AND RESULTS

First, we studied five of the six CAFSA patients initially described. Besides increased CSF free sialic acid concentrations, three patients presented with markedly decreased 5-methyltetrahydrofolate (5-MTHF) CSF concentrations. Exome sequencing identified a homozygous POLG mutation in two affected sisters, but failed to identify a causative gene in the three sporadic patients with high sialic acid but low 5-MTHF. Using targeted mass spectrometry, we confirmed that free sialic acid was increased in the CSF of a third known POLG-mutated patient. We then pursued pathophysiological analyses of CAFSA using mass spectrometry-based metabolomics on CSF from two sporadic CAFSA patients as well as 95 patients with an unexplained encephalopathy and 39 controls. This led to the identification of a common metabotype between the two initial CAFSA patients and three additional patients, including one patient with Kearns-Sayre syndrome. Metabolites of the CSF metabotype were positioned in a reconstruction of the human metabolic network, which highlighted the proximity of the metabotype with acetyl-CoA and carnitine, two key metabolites regulating mitochondrial energy homeostasis.

CONCLUSION

Our genetic and metabolomics analyses suggest that CAFSA is a heterogeneous entity related to mitochondrial DNA alterations either through POLG mutations or a mechanism similar to what is observed in Kearns-Sayre syndrome.

Serum lipidomics reveals early differential effects of gastric bypass compared with banding on phospholipids and sphingolipids independent of differences in weight loss

BACKGROUND/OBJECTIVES

Circulating phospholipids and sphingolipids are implicated in obesity-related comorbidities such as insulin resistance and cardiovascular disease. How bariatric surgery affects these important lipid markers is poorly understood. We sought to determine whether Roux-en-Y gastric bypass (RYGB), which is associated with greater metabolic improvement, differentially affects the phosphosphingolipidome compared with adjustable gastric banding (AGB).

SUBJECTS/METHODS

Fasting sera were available from 59 obese women (body mass index range 37-51 kg m^-2; n=37 RYGB and 22 AGB) before surgery, then at 1 (21 RYGB, 12 AGB) and 3 months follow-up (19 RYGB, 12 AGB). HPLC-MS/MS was used to quantify 131 lipids from nine structural classes. DXA measurements and laboratory parameters were also obtained. The associations between lipids and clinical measurements were studied with P-values adjusted for the false discovery rate (FDR).

RESULTS

Both surgical procedures rapidly induced weight loss and improved clinical profiles, with RYGB producing better improvements in fat mass, and serum total cholesterol, low-density lipoprotein-cholesterol (LDL-C) and orosomucoid (FDR <10%). Ninety-three (of 131) lipids were altered by surgery-the majority decreasing-with 29 lipids differentially affected by RYGB during the study period. The differential effect of the surgeries remained statistically significant for 20 of these lipids after adjusting for differences in weight loss between surgery types. The RYGB signature consisted of phosphatidylcholine species not exceeding 36 carbons, and ceramides and sphingomyelins containing C22 to C25 fatty acids. RYGB also led to a sustained increase in unsaturated ceramide and sphingomyelin species. The RYGB-specific lipid changes were associated with decreases in body weight, total and LDL-C, orosomucoid and increased HOMA-S (FDR <10%).

CONCLUSIONS

Concomitant with greater metabolic improvement, RYGB induced early and sustained changes in phosphatidylcholines, sphingomyelins and ceramides that were independent of greater weight loss. These data suggest that RYGB may specifically alter sphingolipid metabolism, which, in part, could explain the better metabolic outcomes of this surgical procedure.

Comparison of the activation time effects and the internal energy distributions for the CID, PQD and HCD excitation modes

Reproducibility among different types of excitation modes is a major bottleneck in the field of tandem mass spectrometry library development in metabolomics. In this study, we specifically evaluated the influence of collision voltage and activation time parameters on tandem mass spectrometry spectra for various excitation modes [collision-induced dissociation (CID), pulsed Q dissociation (PQD) and higher-energy collision dissociation (HCD)] of Orbitrap-based instruments. For this purpose, internal energy deposition was probed using an approach based on Rice-Rampserger-Kassel-Marcus modeling with three thermometer compounds of different degree of freedom (69, 228 and 420) and a thermal model. This model treats consecutively the activation and decomposition steps, and the survival precursor ion populations are characterized by truncated Maxwell-Boltzmann internal energy distributions. This study demonstrates that the activation time has a significant impact on MS/MS spectra using the CID and PQD modes. The proposed model seems suitable to describe the multiple collision regime in the PQD and HCD modes. Linear relationships between mean internal energy and collision voltage are shown for the latter modes and the three thermometer molecules. These results suggest that a calibration based on the collision voltage should provide reproducible for PQD, HCD to be compared with CID in tandem in space instruments. However, an important signal loss is observed in PQD excitation mode whatever the mass of the studied compounds, which may affect not only parent ions but also fragment ions depending on the fragmentation parameters. A calibration approach for the CID mode based on the variation of activation time parameter is more appropriate than one based on collision voltage. In fact, the activation time parameter in CID induces a modification of the collisional regime and thus helps control the orientation of the fragmentation pathways (competitive or consecutive dissociations).

Identification tree based on fragmentation rules for structure elucidation of organophosphorus esters by electrospray mass spectrometry

Organophosphorus compounds have played important roles as pesticides, chemical warfare agents and extractors of radioactive material. Structural elucidation of phosphonates poses a particular challenge because their initial forms can be hydrolyzed, thus, degradation products may predominate in samples acquired in the field. The analysis of non-volatile organophosphorus compounds and their degradation products is possible using electrospray tandem mass spectrometry ESI-MS/MS. Here, we present a generic strategy that allows the unambiguous identification of substituents for two families of organophosphorus compounds: the phosphonates and phosphates. General fragmentation rules were deduced based on the study of decomposition pathways of 55 organophosphorus esters, including examples found in the literature. Multistage MS (MS(n)) experiments at high resolution in a hybrid mass spectrometer provide accurate mass measurements, whereas collision-induced dissociation experiments in a triple quadrupole give access to small fragment ions. The creation of a specific nomenclature for each possible structure of organophosphorus compound, depending on the alkyl side chain linked to the oxygen, was achieved by applying these fragmentation rules. This led to the creation of an 'identification tree' based upon the unique consecutive decomposition pathways uncovered for each individual compound. Hence, seven structural motifs were created that orient an unequivocal identification using the 'identification tree'. Despite the similar structures of the ensemble of phosphate and phosphonate esters, distinct identifications based upon characteristic neutral losses and diagnostic fragment ions were possible in all cases.

Collision cell pressure effect on CID spectra pattern using triple quadrupole instruments: a RRKM modeling

Control of the ion internal energy in mass spectrometry is needed to establish a workable mass spectral library. The purpose of this study is to understand and to compare the pressure effects on the collision-induced dissociation (CID) spectrum pattern recorded using triple quadrupole instruments. The monoprotonated Leucine enkephalin [YGGFL, H(+)] was used as a thermometer molecule to calibrate the electrospray ionization (ESI) and the CID internal energies deposited on the molecular species and the time scale of ion decompositions. The survival yield and the ratio of a(4)/b(4) fragment ions were mainly monitored. The energy uptake for the ESI source geometry used in our study has no impact on the CID spectrum fingerprint. The collision cell pressure for the [YGGFL, H(+)] has a major influence on the SY curves slope and on the experimental time scale. To demonstrate the pressure effect on internal energy distribution, three models (threshold, thermal and collisional) based on RRKM theory were built using the Masskinetics software. As a result, the limit of each model is discussed, and the investigation demonstrates that the thermal model, using truncated Maxwell-Boltzmann internal energy distribution, is well-suited for simulating the experimental data at high pressure widely used in the analytical conditions.

Cost saving of 5-day therapy with cefpodoxime proxetil versus standard 10-day beta-lactam therapy for recurrent pharyngotonsillitis in adults. A prospective general practice study

A prospective economic evaluation was undertaken as part of a randomised clinical trial conducted in French general practice. Its aim was to compare the costs and therapeutic outcomes of a 5-day course of cefpodoxime proxetil 100 mg twice daily with 10-day courses of phenoxymethylpenicillin (penicillin V) 1 MIU 3 times daily and amoxicillin-clavulanic acid 500/125 mg 3 times daily for the treatment of recurrent pharyngotonsillitis in 575 adults. Over the 6-month study period, the total cost to society per patient treated with cefpodoxime proxetil was 123 French francs (FF; 1993 values) lower than that for patients treated with phenoxymethylpenicillin and FF227 lower than that for patients treated with amoxicillin-clavulanic acid. This cost saving was primarily attributable to a lower initial drug acquisition cost, and a reduction in the cost associated with lost productivity and general practitioner consultations. Furthermore, as a consequence of a lower relapse rate, the cost-saving ratio for cefpodoxime proxetil, expressed as FF per month free of recurrence, was FF50 less than for phenoxymethylpenicillin and FF60 less than for amoxicillin-clavulanic acid. Thus, a 5-day course of cefpodoxime proxetil is likely to be less costly for treatment of pharyngotonsillitis in the general practice setting than standard 10-day courses of phenoxymethylpenicillin and amoxicillin-clavulanic acid.

Five versus ten days treatment of streptococcal pharyngotonsillitis: a randomized controlled trial comparing cefpodoxime proxetil and phenoxymethyl penicillin

A total of 220 adults and children > 10 years old (mean 29.5 +/- 11.7 years) with pharyngitis/tonsillitis were randomized to receive either cefpodoxime proxetil 100 mg bid for 5 days (n = 113) or phenoxymethyl penicillin, 600 mg tid for 10 days (n = 107). At the end of treatment of the 166 evaluable patients, a satisfactory clinical response was obtained in 85/88 (96.6%) patients treated with cefpodoxime proxetil and in 75/78 (96.1%) treated with phenoxymethyl penicillin. Group A beta-hemolytic streptococci (GABHS) eradication was similar in both groups: 79/82 (96.3%) patients in the cefpodoxime proxetil group and 64/68 (94.1%) patients in the phenoxymethyl penicillin group. At follow-up (20-30 days after the end of treatment) the GABHS eradication persisted in 67/72 (93.1%) patients treated with cefpodoxime proxetil and in 56/61 (91.8%) patients treated with phenoxymethyl penicillin. Significantly better compliance (p < 0.01) was noticed with the cefpodoxime proxetil regimen compared with the phenoxymethyl penicillin regimen, with only 2/110 (2%) poorly compliant patients in the cefpodoxime proxetil group vs 17/104 (16%) in the phenoxymethyl penicillin group. Thus, the shorter duration of therapy, in conjunction with demonstrated clinical and bacteriological efficacy that is equivalent to standard therapy, makes cefpodoxime proxetil an acceptable alternative for the treatment of GABHS pharyngitis/tonsillitis.

Efficacy and tolerance of cefpodoxime proxetil compared with ceftriaxone in vulnerable patients with bronchopneumonia

This multicentre, randomized study compared the efficacy and tolerance of cefpodoxime proxetil and ceftriaxone in vulnerable patients with bronchopneumonia. Patients received cefpodoxime proxetil 200 mg bd orally or ceftriaxone 1 g daily im for a ten-day period. They were evaluated at days 10 and 30. Ninety-six patients were evaluated for tolerance, 85 for clinical efficacy and 65 for bacteriological efficacy. At entry all patients had radiographic evidence of pneumonia and 74% of bacteriological samples were positive. The percentage of overall success (cured or improved) was 97.7% (43/44) in the cefpodoxime proxetil group and 95.1% (39/41) in the ceftriaxone group. The bacteriological efficacy was 94.3% in the cefpodoxime proxetil group and 97.4% in the ceftriaxone group. Clinical tolerance was satisfactory in both groups. In this study, the clinical and bacteriological results obtained with cefpodoxime proxetil were comparable with those obtained with ceftriaxone in the treatment of community-acquired bronchopneumonia in patients with additional risk factors.

Concentrations of cefpodoxime in plasma and tonsillar tissue after a single oral dose of cefpodoxime proxetil

Seventeen patients undergoing tonsillectomy received cefpodoxime proxetil orally in a dose equivalent to 100 mg cefpodoxime 4, 7 or 12 h before operation. Plasma and tonsillar tissue concentrations of cefpodoxime were assayed by a microbiological method. Tonsillar tissue concentrations after 4 and 7 h were 0.24 and 0.09 mg/kg respectively--being 23% of the plasma concentration. The tonsillar tissue concentration after 12 h was less than 0.06 mg/kg. As the MIC for Streptococcus pyogenes is less than 0.06 mg/l, cefpodoxime proxetil may be of value in acute tonsillitis.

[In vivo study of the sensitivity of Treponema pallidum to ofloxacin]

Treponema pallidum has not been yet cultivated. Hence any in vitro investigation is excluded, and it is owing to the experimental animal model, the rabbit, that we have studied the susceptibility of that germ to ofloxacin. This quinolone, owing to its pharmacokinetic and therapeutic properties, can specially be indicated in the treatment of Sexually Transmitted Diseases. Thus, its appeared to be of the utmost importance to know if the suggested schedule of treatment for STD, might not be susceptible to modify the course of a co-existing incubating syphilis by either delaying or inhibiting the apparition of the clinical features of primary syphilis. This study was undertaken at the incubation period, in syphilitic rabbits, using kinetic data obtained in man, after a given dosage of ofloxacin. Results were appraised upon converging data: lesions, bacteriology, and serology of the tested lot compared with two control batches of infected rabbits, the first one being untreated, the other having received the reference antibiotic treatment. From the data obtained and in the experimental settled conditions where this study was done, it results that ofloxacin has no effect on the course of the experimental syphilitic infection.

Bactericidal effect of ofloxacin alone and combined with fosfomycin or vancomycin against Staphylococcus aureus in vitro and in sera from volunteers

The bactericidal activity of ofloxacin alone and in combination was evaluated against strains of Staphylococcus aureus by measuring MBCs, FBC indexes and by the killing curve technique. Bactericidal titres were determined in sera from volunteers given ofloxacin alone or in combination with fosfomycin or vancomycin. FBC indices less than 0.75 were observed with fosfomycin, showing moderate synergy. FBC indices of 1 were seen with vancomycin. Killing kinetic experiments indicated that ofloxacin (1 and 4 mg/l) exerted a rapid bactericidal effect (99.9% killing in 4 h); the combination of ofloxacin and fosfomycin was synergistic for one of three strains, while killing kinetics of ofloxacin were unaltered by fosfomycin for two of three strains or by vancomycin for the three strains. Sera collected two hours after ofloxacin or fosfomycin had been administered had bactericidal titres less than 1/2. Bactericidal titres were significantly greater in sera from volunteers given the combination of these two drugs. Similar bactericidal titres were obtained in sera after the administration of vancomycin alone or in combination with ofloxacin. A loading dose of 400 mg ofloxacin with subsequent doses of 200 mg had no significantly prolonged effect on bactericidal titres.