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Background : This study reviews the surgical and functional outcomes of children diagnosed with a bilateral cleft lip and palate and treated by the same surgical team following specific surgical protocols 18 years after surgery and during the follow-up. Methods : Based on a single-center retrospective design, demographic and surgical data were gathered by the authors from international institutions. Most of the data were quantitative in nature, and descriptive statistical and non-parametric tests were employed for analysis. All children born with a bilateral cleft from 1982 to 2002 were considered. Children affected by a syndrome were excluded. Complications and speech results were the main items measured. Results: Thirty patients were selected; 73.3% were treated using the inverse Malek procedure, and 26.7% underwent a modified two-stage procedure. Seventy percent developed an oronasal fistula. An alveolar bone graft was performed in 83%, and 53.3% underwent Le Fort osteotomy. Thirty-six percent required a pharyngeal flap, with good speech results. The median number of times general anesthesia was used among all the interventions considered was 5.5 (4.25-6). Conclusions: This study presents the long-term results of using the inverse Malek procedure to treat children with a bilateral cleft lip and palate. It is shown that this is related to a high risk of developing a fistula, but has good long-term speech results.

Purpose: Lymphatic malformations (LMs) are classified as macrocystic, microcystic or mixed. Treatment depends on their characteristics: surgery, sclerotherapy, both combined, systemic treatment or observation. This study aims to analyze the surgical and interventional management of LMs in children over the last two decades in our university hospital., Methods: Management of children born with LMs between 2000 and 2019 was reviewed. Parameters collected were: malformation characteristics, type of treatment, symptoms, imaging, timing of diagnosis and first treatment, number of interventions, recovery rate, complications and length of stay., Results: Files of 48 children were reviewed: 27 with macrocystic and 21 with microcystic LMs. There was no statistically significant difference in type of treatment except for combined treatment, more performed in microcystic LMs (p = 0.04). Symptoms, imaging, timing of diagnosis and first treatment, number of interventions and complications were not statistically significant. Overall, the number of surgeries was lower than sclerotherapies (p = 0.04). Recovery rate after surgery was higher in macrocystic LMs (p = 0.01). Complications and length of stay were not statistically significant., Conclusion: A good rate of recovery was observed when surgery was performed, with no significant increase in complications and length of stay. A prospective study will be determinant to create a decisional algorithm for children with LMs., (© 2022. The Author(s).)

Metabolism regulates cell fates during early mammalian cell differentiation. This protocol describes the steps for directed differentiation of primed human pluripotent stem cells (hPSCs) into the three primary germ lineages-ectoderm, endoderm, and mesoderm-using a chemically defined nutrient-balanced media formulation. Although the transient removal and addition of specific nutrients does not occur in vivo during embryonic development, manipulation of nutrients in vitro provides an accessible method for evaluating how extracellular and intracellular metabolites help determine hPSC fate. For complete details on the use and execution of this protocol, please refer to Lu et al. (2019) and Lu et al. (2022)., Competing Interests: The authors declare no competing interests., (© 2022 The Author(s).)

Anabolic metabolism of carbon in mammals is mediated via the one- and two-carbon carriers S-adenosyl methionine and acetyl-coenzyme A. In contrast, anabolic metabolism of three-carbon units via propionate has not been shown to extensively occur. Mammals are primarily thought to oxidize the three-carbon short chain fatty acid propionate by shunting propionyl-CoA to succinyl-CoA for entry into the TCA cycle. Here, we found that this may not be absolute as, in mammals, one nonoxidative fate of propionyl-CoA is to condense to two three-carbon units into a six-carbon trans-2-methyl-2-pentenoyl-CoA (2M2PE-CoA). We confirmed this reaction pathway using purified protein extracts provided limited substrates and verified the product via LC-MS using a synthetic standard. In whole-body in vivo stable isotope tracing following infusion of 13 C-labeled valine at steady state, 2M2PE-CoA was found to form via propionyl-CoA in multiple murine tissues, including heart, kidney, and to a lesser degree, in brown adipose tissue, liver, and tibialis anterior muscle. Using ex vivo isotope tracing, we found that 2M2PE-CoA also formed in human myocardial tissue incubated with propionate to a limited extent. While the complete enzymology of this pathway remains to be elucidated, these results confirm the in vivo existence of at least one anabolic three- to six-carbon reaction conserved in humans and mice that utilizes propionate., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Glioblastomas (GBMs) preferentially generate acetyl-CoA from acetate as a fuel source to promote tumor growth. O-GlcNAcylation has been shown to be elevated by increasing O-GlcNAc transferase (OGT) in many cancers and reduced O-GlcNAcylation can block cancer growth. Here, we identify a novel mechanism whereby OGT regulates acetate-dependent acetyl-CoA and lipid production by regulating phosphorylation of acetyl-CoA synthetase 2 (ACSS2) by cyclin-dependent kinase 5 (CDK5). OGT is required and sufficient for GBM cell growth and regulates acetate conversion to acetyl-CoA and lipids. Elevating O-GlcNAcylation in GBM cells increases phosphorylation of ACSS2 on Ser-267 in a CDK5-dependent manner. Importantly, we show that ACSS2 Ser-267 phosphorylation regulates its stability by reducing polyubiquitination and degradation. ACSS2 Ser-267 is critical for OGT-mediated GBM growth as overexpression of ACSS2 Ser-267 phospho-mimetic rescues growth in vitro and in vivo. Importantly, we show that pharmacologically targeting OGT and CDK5 reduces GBM growth ex vivo. Thus, the OGT/CDK5/ACSS2 pathway may be a way to target altered metabolic dependencies in brain tumors., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Cumulus cell (CC) clumps that associate with oocytes provide the oocytes with growth and signaling factors. Thus, the metabolism of the CCs may influence oocyte function, and CC metabolism may be predictive of oocyte competence for in vitro fertilization. CCs are thought to be highly glycolytic, but data on the use of other potential carbon substrates are lacking in humans. This prospective and blinded cohort study was designed to examine the substrate utilization of CCs by age and oocyte competence. Individual sets of CC clumps from participants were removed after oocyte retrieval procedure then, incubated with stable isotope labeled substrates, and analyzed using liquid chromatography-high resolution mass spectrometry (LC-HRMS) for isotopologue enrichment of major metabolic intermediates, including acetyl-CoA. The acyl-chain of acetyl-CoA contains 2 carbons that can be derived from 13 C-labeled substrates resulting in an M + 2 isotopologue that contains 2 13 C atoms. Comparing the fate of three major carbon sources, mean enrichment of M + 2 acetyl-CoA (mean, standard deviation) was for glucose (3.6, 7.7), for glutamine (9.4, 6.2), and for acetate (20.7, 13.9). Due to this unexpected high and variable labeling from acetate, we then examined acetyl-CoA mean % enrichment from acetate in 278 CCs from 21 women ≤34 (49.06, 12.73) decreased with age compared to 124 CCs from 10 women >34 (43.48, 16.20) (p = 0.0004, t-test). The CCs associated with the immature prophase I oocytes had significantly lower enrichment in M + 2 acetyl CoA compared to the CCs associated with the metaphase I and metaphase II oocytes (difference: -6.02, CI: -1.74,-13.79, p = 0.013). Acetate metabolism in individual CC clumps was positively correlated with oocyte maturity and decreased with maternal age. These findings indicate that CC metabolism of non-glucose substrates should be investigated relative to oocyte function and age-related fertility. Abbreviations: CCs: cumulus cells; COC: cumulus-oocyte complex; LC-MS: liquid chromatography-mass spectrometry; acetyl-CoA: acetyl-Coenzyme A; CoA: Coenzyme A.

Quantitative subcellular metabolomic measurements can explain the roles of metabolites in cellular processes but are subject to multiple confounding factors. We developed stable isotope labeling of essential nutrients in cell culture-subcellular fractionation (SILEC-SF), which uses isotope-labeled internal standard controls that are present throughout fractionation and processing to quantify acyl-coenzyme A (acyl-CoA) thioesters in subcellular compartments by liquid chromatography-mass spectrometry. We tested SILEC-SF in a range of sample types and examined the compartmentalized responses to oxygen tension, cellular differentiation, and nutrient availability. Application of SILEC-SF to the challenging analysis of the nuclear compartment revealed a nuclear acyl-CoA profile distinct from that of the cytosol, with notable nuclear enrichment of propionyl-CoA. Using isotope tracing, we identified the branched chain amino acid isoleucine as a major metabolic source of nuclear propionyl-CoA and histone propionylation, thus revealing a new mechanism of crosstalk between metabolism and the epigenome., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Carnitine palmitoyltransferase-1 (CPT-1) is a rate-controlling enzyme for long-chain fatty acid oxidation. This manuscript provides protocols for measuring CPT-1-mediated respiration in permeabilized, adherent cell monolayers and mitochondria freshly isolated from tissue, along with examples to assess the potency and specificity of interventions targeting CPT-1. Strengths of the approach include ease, speed, and breadth of analysis, whereas drawbacks include loss of physiological regulation in reductionist systems and indirect assessment of CPT-1 enzymatic activity. For complete details on the use and execution of this protocol, please refer to Divakaruni et al. (2018)., Competing Interests: A.S.D. has previously served as a paid consultant for Agilent Technologies., (© 2021 The Authors.)

Histone crotonylation is a non-acetyl histone lysine modification that is as widespread as acetylation. However, physiological functions associated with histone crotonylation remain almost completely unknown. Here we report that histone crotonylation is crucial for endoderm differentiation. We demonstrate that key crotonyl-coenzyme A (CoA)-producing enzymes are specifically induced in endodermal cells during differentiation of human embryonic stem cells (hESCs) in vitro and in mouse embryos, where they function to increase histone crotonylation and enhance endodermal gene expression. Chemical enhancement of histone crotonylation promotes endoderm differentiation of hESCs, whereas deletion of crotonyl-CoA-producing enzymes reduces histone crotonylation and impairs meso/endoderm differentiation in vitro and in vivo. Our study uncovers a histone crotonylation-mediated mechanism that promotes endodermal commitment of pluripotent stem cells, which may have important implications for therapeutic strategies against a number of human diseases., Competing Interests: Declaration of interests Y.Z. is on the science advisory board of PTM Biolabs., (Published by Elsevier Inc.)

Cassaine diterpenoids as erythrofordins A-C (1-3), pseudo-erythrosuamin (4), and erythrofordin U (5) isolated from the leaves of Vietnamese Erythrophleum fordii Oliver were tested cytotoxic activity against human leukemia cancer cells. The results showed that these metabolites exhibited dose-dependent cytotoxicity against human leukemia HL-60 and KG cells with IC 50 values ranging from 15.2 ± 1.5 to 42.2 ± 3.6 µM. Treatment with erythrofordin B led to the apoptosis of HL-60 and KG cells due to the activation of caspase 3, caspase 9, and poly (ADP-ribose) polymerase (PARP). Erythrofordin B significantly increased Bak protein expression, but downregulated the anti-apoptotic protein Bcl-2, in HL-60 cells. In silico results demonstrated that erythrofordin B can bind to both the procaspase-3 allosteric site and the PARP-1 active site, with binding energies of -7.36 and -10.76 kcal/mol, respectively. These results indicated that the leaves of Vietnamese E. fordii, which contain cassaine diterpenoids, can induce the apoptosis of human leukemia cancer cells., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Objective: The dynamic regulation of metabolic pathways can be monitored by stable isotope tracing. Yet, many metabolites are part of distinct processes within different subcellular compartments. Standard isotope tracing experiments relying on analyses in whole cells may not accurately reflect compartmentalized metabolic processes. Analysis of compartmentalized metabolism and the dynamic interplay between compartments can potentially be achieved by stable isotope tracing followed by subcellular fractionation. Although it is recognized that metabolism can take place during biochemical fractionation of cells, a clear understanding of how such post-harvest metabolism impacts the interpretation of subcellular isotope tracing data and methods to correct for this are lacking. We set out to directly assess artifactual metabolism, enabling us to develop and test strategies to correct for it. We apply these techniques to examine the compartment-specific metabolic kinetics of 13 C-labeled substrates targeting central metabolic pathways., Methods: We designed a stable isotope tracing strategy to interrogate post-harvest metabolic activity during subcellular fractionation using liquid chromatography-mass spectrometry (LC-MS)., Results: We show that post-harvest metabolic activity occurs rapidly (within seconds) upon cell harvest. With further characterization we reveal that this post-harvest metabolism is enzymatic and reflects the metabolic capacity of the sub-cellular compartment analyzed, but it is limited in the extent of its propagation into downstream metabolites in metabolic pathways. We also propose and test a post-labeling strategy to assess the amount of post-harvest metabolism occurring in an experiment and then to adjust data to account for this. We validate this approach for both mitochondrial and cytosolic metabolic analyses., Conclusions: Our data indicate that isotope tracing coupled with sub-cellular fractionation can reveal distinct and dynamic metabolic features of cellular compartments, and that confidence in such data can be improved by applying a post-labeling correction strategy. We examine compartmentalized metabolism of acetate and glutamine and show that acetyl-CoA is turned over rapidly in the cytosol and acts as a pacemaker of anabolic metabolism in this compartment., (Copyright © 2019 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Macrophages are activated during microbial infection to coordinate inflammatory responses and host defense. Here we find that in macrophages activated by bacterial lipopolysaccharide (LPS), mitochondrial glycerol 3-phosphate dehydrogenase (GPD2) regulates glucose oxidation to drive inflammatory responses. GPD2, a component of the glycerol phosphate shuttle, boosts glucose oxidation to fuel the production of acetyl coenzyme A, acetylation of histones and induction of genes encoding inflammatory mediators. While acute exposure to LPS drives macrophage activation, prolonged exposure to LPS triggers tolerance to LPS, where macrophages induce immunosuppression to limit the detrimental effects of sustained inflammation. The shift in the inflammatory response is modulated by GPD2, which coordinates a shutdown of oxidative metabolism; this limits the availability of acetyl coenzyme A for histone acetylation at genes encoding inflammatory mediators and thus contributes to the suppression of inflammatory responses. Therefore, GPD2 and the glycerol phosphate shuttle integrate the extent of microbial stimulation with glucose oxidation to balance the beneficial and detrimental effects of the inflammatory response.

Reprogrammed metabolism and cell cycle dysregulation are two cancer hallmarks. p16 is a cell cycle inhibitor and tumor suppressor that is upregulated during oncogene-induced senescence (OIS). Loss of p16 allows for uninhibited cell cycle progression, bypass of OIS, and tumorigenesis. Whether p16 loss affects pro-tumorigenic metabolism is unclear. We report that suppression of p16 plays a central role in reprogramming metabolism by increasing nucleotide synthesis. This occurs by activation of mTORC1 signaling, which directly mediates increased translation of the mRNA encoding ribose-5-phosphate isomerase A (RPIA), a pentose phosphate pathway enzyme. p16 loss correlates with activation of the mTORC1-RPIA axis in multiple cancer types. Suppression of RPIA inhibits proliferation only in p16-low cells by inducing senescence both in vitro and in vivo. These data reveal the molecular basis whereby p16 loss modulates pro-tumorigenic metabolism through mTORC1-mediated upregulation of nucleotide synthesis and reveals a metabolic vulnerability of p16-null cancer cells., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Diseases associated with mitochondrial DNA (mtDNA) mutations are highly variable in phenotype, in large part because of differences in the percentage of normal and mutant mtDNAs (heteroplasmy) present within the cell. For example, increasing heteroplasmy levels of the mtDNA tRNA Leu(UUR) nucleotide (nt) 3243A > G mutation result successively in diabetes, neuromuscular degenerative disease, and perinatal lethality. These phenotypes are associated with differences in mitochondrial function and nuclear DNA (nDNA) gene expression, which are recapitulated in cybrid cell lines with different percentages of m.3243G mutant mtDNAs. Using metabolic tracing, histone mass spectrometry, and NADH fluorescence lifetime imaging microscopy in these cells, we now show that increasing levels of this single mtDNA mutation cause profound changes in the nuclear epigenome. At high heteroplasmy, mitochondrially derived acetyl-CoA levels decrease causing decreased histone H4 acetylation, with glutamine-derived acetyl-CoA compensating when glucose-derived acetyl-CoA is limiting. In contrast, α-ketoglutarate levels increase at midlevel heteroplasmy and are inversely correlated with histone H3 methylation. Inhibition of mitochondrial protein synthesis induces acetylation and methylation changes, and restoration of mitochondrial function reverses these effects. mtDNA heteroplasmy also affects mitochondrial NAD + /NADH ratio, which correlates with nuclear histone acetylation, whereas nuclear NAD + /NADH ratio correlates with changes in nDNA and mtDNA transcription. Thus, mutations in the mtDNA cause distinct metabolic and epigenomic changes at different heteroplasmy levels, potentially explaining transcriptional and phenotypic variability of mitochondrial disease., Competing Interests: The authors declare no conflict of interest., (Copyright © 2019 the Author(s). Published by PNAS.)

The precursor cells for metabolically beneficial beige adipocytes can alternatively become fibrogenic and contribute to adipose fibrosis. We found that cold exposure or β3-adrenergic agonist treatment of mice decreased the fibrogenic profile of precursor cells and stimulated beige adipocyte differentiation. This fibrogenic-to-adipogenic transition was impaired in aged animals, correlating with reduced adipocyte expression of the transcription factor PRDM16. Genetic loss of Prdm16 mimicked the effect of aging in promoting fibrosis, whereas increasing PRDM16 in aged mice decreased fibrosis and restored beige adipose development. PRDM16-expressing adipose cells secreted the metabolite β-hydroxybutyrate (BHB), which blocked precursor fibrogenesis and facilitated beige adipogenesis. BHB catabolism in precursor cells, mediated by BDH1, was required for beige fat differentiation in vivo. Finally, dietary BHB supplementation in aged animals reduced adipose fibrosis and promoted beige fat formation. Together, our results demonstrate that adipocytes secrete a metabolite signal that controls beige fat remodeling., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Coparenting between biological parents is a strong predictor of child adjustment. To date, however, little is known about the coparenting dynamics between parent and stepparent in stepfamilies. This study aimed at exploring the links between coparenting in the mother-stepfather dyad and child behavior in stepfamilies compared with the links between mother-father coparenting and child behavior in first-marriage families. Two modes of coparenting were assessed: overt coparenting, that is, coparental behaviors in the presence of the child, and covert coparenting, that is, the way each parent speaks of the other parent to the child. The sample (N = 80) comprised 48 stepfamilies and 32 first-marriage families with a child between 7 and 13 years old. Overt coparenting was assessed through direct observation in the standardized situation of the PicNic Game. Covert coparenting and child behavior were assessed through mother-reported questionnaires. Results showed (a) more covert coparenting behaviors in first-marriage families, (b) no differences in overt coparenting, (c) more child difficulties reported in stepfamilies, (d) less optimal overt coparenting being linked with more difficulties in children in both family structures, and (e) an interaction effect between family structure and coparenting, showing that overt coparenting is linked with child behavior mainly in stepfamilies., (© 2018 Family Process Institute.)

Quantification of cellular deoxyribonucleoside mono- (dNMP), di- (dNDP), triphosphates (dNTPs) and related nucleoside metabolites are difficult due to their physiochemical properties and widely varying abundance. Involvement of dNTP metabolism in cellular processes including senescence and pathophysiological processes including cancer and viral infection make dNTP metabolism an important bioanalytical target. We modified a previously developed ion pairing reversed phase chromatography-mass spectrometry method for the simultaneous quantification and 13 C isotope tracing of dNTP metabolites. dNMPs, dNDPs, and dNTPs were chromatographically resolved to avoid mis-annotation of in-source fragmentation. We used commercially available 13 C 15 N-stable isotope labeled analogs as internal standards and show that this isotope dilution approach improves analytical figures of merit. At sufficiently high mass resolution achievable on an Orbitrap mass analyzer, stable isotope resolved metabolomics allows simultaneous isotope dilution quantification and 13 C isotope tracing from major substrates including 13 C-glucose. As a proof of principle, we quantified dNMP, dNDP and dNTP pools from multiple cell lines. We also identified isotopologue enrichment from glucose corresponding to ribose from the pentose-phosphate pathway in dNTP metabolites., (Copyright © 2018. Published by Elsevier Inc.)

Objective: Cancer diagnosis during pregnancy occurs in 1 out of 1000 pregnancies with common malignancies including breast and hematological cancers. Fetal exposure to currently utilized agents is poorly described. We directly assessed fetal exposure by screening meconium from 23 newborns whose mothers had undergone treatment for cancer during pregnancy., Study Design: Meconium was collected from newborns whose mothers were diagnosed with cancer during pregnancy and underwent chemotherapy in the second or third trimester as part of the Cancer and Pregnancy Registry. We conducted screening of 23 meconium samples for chemotherapeutics and known metabolites of chemotherapeutics by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Putative identification of paclitaxel and/or its metabolites was made in 8 screened samples. In positively screened samples, we quantified paclitaxel, 3'-p-hydroxypaclitaxel, and 6α-hydroxypaclitaxel by stable isotope dilution-LC-HRMS., Results: Mean (standard deviation) levels of paclitaxel in positively screened samples were 399.9 (248.6) pg/mg in meconium samples from newborn born to mothers that underwent chemotherapy during pregnancy. 3'-p-hydroxypaclitaxel and 6α-hydroxypaclitaxel mean levels were 105.2 (54.6) and 113.4 (48.9) pg/mg meconium, respectively., Conclusion: Intact paclitaxel, 3'-p-hydroxypaclitaxel, and 6α-hydroxypaclitaxel were detected in meconium, providing unambiguous confirmation of human fetal exposure. Variability in meconium levels between individuals may indicate a potential for reducing fetal exposure based on timing, dosing, and individual characteristics. This preliminary study may provide an approach for examining the effects of cancer diagnosis during pregnancy on other outcomes by providing a measure of direct fetal exposure., Competing Interests: The authors have declared that no competing interests exist.

Dynamic interplay between cellular metabolism and histone acetylation is a key mechanism underlying metabolic control of epigenetics. In particular, the central metabolite acetyl-coenzyme A (acetyl-CoA) acts as the acetyl-donor for histone acetylation in both an enzymatic and non-enzymatic manner. Since members of the family of histone acetyl transferases (HATs) that catalyze the acetylation of histone tails possess a Michaelis constant (Km) within the range of physiological cellular acetyl-CoA concentrations, changing concentrations of acetyl-CoA can restrict or promote enzymatic histone acetylation. Likewise, non-enzymatic histone acetylation occurs at physiological concentrations. These concepts implicate acetyl-CoA as a rheostat for nutrient availability acting, in part, by controlling histone acetylation. Histone acetylation is an important epigenetic modification that controls gene expression and acetyl-CoA dependent changes in both histone acetylation and gene expression have been shown in yeast and mammalian systems. However, quantifying the metabolic conditions required to achieve specific changes in histone acetylation is a major challenge. The relationship between acetyl-CoA and histone acetylation may be influenced by a variety of factors including sub-cellular location of metabolites and enzymes, relative quantities of metabolites, and substrate availability/preference. A diversity of substrates can contribute the two-carbon acyl-chain to acetyl-CoA, a number of pathways can create or degrade acetyl-CoA, and only a handful of potential mechanisms for the crosstalk between metabolism and histone acetylation have been explored. The centrality of acetyl-CoA in intermediary metabolism means that acetyl-CoA levels may change, or be resistant to change, in unexpected ways. Thus, quantification of relevant metabolites is critical evidence in understanding how the nutrient rheostat is set in normal and pathological contexts. Coupling metabolite quantitation with isotope tracing to examine fate of specific metabolites is critical to the crosstalk between metabolism and histone acetylation, including but not limited to acetyl-CoA provides necessary context. This chapter provides guidance on experimental design of quantification with isotope dilution and/or tracing of acetyl-CoA within a targeted or highly multiplexed multi-analyte workflow., (© 2019 Elsevier Inc. All rights reserved.)

Rationale: Lactate and pyruvate are high abundance products of glucose metabolism. Analysis of both molecules as part of metabolomics studies in cellular metabolism and physiology have been aided by advances in liquid chromatography-mass spectrometry (LC-MS)., Methods: We used ion pairing-chromatography and negative ion mode ESI on an QExactive HF to perform stable isotope assisted metabolomics profiling of lactate and pyruvate metabolism., Results: Using an LC-MS method for polar metabolite analysis we discovered an artefactual formation of pyruvate from in-source fragmentation of lactate. Surprisingly, this in-source fragmentation has not been previously described, thus we report this identification to warn other investigators. This artefact was detected by baseline chromatographic resolution of lactate and pyruvate by LC with confirmation of this artefact by stable isotope labeling of lactate and pyruvate., Conclusions: These findings have immediate implications for metabolomics studies by LC-MS and direct infusion MS, especially in negative ion mode, whereby users should resolve lactate from pyruvate or robustly quantify the potential formation of pyruvate from higher abundance lactate in their assays., (This article is protected by copyright. All rights reserved.)

We report the observation of imaging beyond the diffraction limit due to bound surface states in negative refraction photonic crystals. We achieve an effective negative index figure of merit [-Re(n)/Im(n)] of at least 380, approximately 125x improvement over recent efforts in the near-infrared range, with a 0.4 THz bandwidth. Supported by numerical and theoretical analyses, the observed near-field resolution is 0.47lambda, clearly smaller than the diffraction limit of 0.61lambda. Importantly, we show this subdiffraction imaging is due to the resonant excitation of surface slab modes.

A novel mode transformer was fabricated that transforms a modal area by a factor of 100. Using the mode transformer improves the efficiency of mode transformation by an order of magnitude compared with that when no mode transformer is used. With this mode transformer, input-output coupling of miniaturized, on-chip integrated optical circuits to external optical fibers is achieved with low loss. The mode transformer's design, fabricated in silicon, is scalable to virtually any waveguide size, facilitating continuous miniaturization in silicon optoelectronics.