Defocus incorporated multiple segments (DIMS) spectacle lenses increase the choroidal thickness: a two-year randomized clinical trial

BACKGROUND

Myopia control interventions, such as defocus incorporated multiple segments (DIMS) spectacle lenses, have been adopted in school-aged children to reduce the prevalence of myopia and its complications. This study aimed to investigate the effect of DIMS spectacle lenses on subfoveal choroidal thickness (SfChT) over a period of two years, as the choroidal response to myopic control is a crucial factor in exploring its potential effect on predicting myopia progression.

METHODS

This study involved a secondary analysis of our previous randomized clinical trial. Myopic school-aged children aged 8-13 years were recruited in a two-year study investigating the effect of DIMS spectacle lenses on myopia progression. The treated group received DIMS spectacle lenses (n = 78), while the control group was treated with a pair of single vision (SV) spectacle lenses (n = 80). SfChT was monitored at 1 week, 1, 3, 6, 12, 18 and 24 months post lens wear using spectral-domain optical coherence tomography and a custom made auto-segmentation algorithm utilizing convolutional neural networks.

RESULTS

SfChT increased significantly after one week of DIMS spectacle lens wear compared to those wearing SV spectacle lenses (adjusted mean change relative to baseline ± SEM at one week; DIMS vs. SV, 6.75 ± 1.52 µm vs. - 3.17 ± 1.48 µm; P < 0.0001, general linear model). The thickness of choroid increased to 13.64 ± 2.62 µm after 12 months of DIMS lens wear while the choroid thinned in SV group (- 9.46 ± 2.55 µm). Choroidal changes demonstrated a significant negative association with axial elongation over two years in both the DIMS and SV groups. Choroidal change at three months significantly predicted the changes in AL at 12 months after controlling the effect of age and gender.

CONCLUSIONS

Our study demonstrated a significant choroidal thickening in response to myopic defocus incorporated in a spectacle lens after one week of lens wear, sustained over the two-year study period. The results suggested that choroidal changes at three months may help predict changes in axial length after one year. Trial registration ClinicalTrials.gov. Myopia control with the multi-segment lens. NCT02206217. Registered 29 July 2014, https://clinicaltrials.gov/ct2/show/study/NCT02206217.

Dynamic Instrumental and Sensory Methods Used to Link Aroma Release and Aroma Perception: A Review

Perception of flavor is a dynamic process during which the concentration of aroma molecules at the olfactory epithelium varies with time as they are released progressively from the food in the mouth during consumption. The release kinetics depends on the food matrix itself but also on food oral processing, such as mastication behavior and food bolus formation with saliva, for which huge inter-individual variations exist due to physiological differences. Sensory methods such as time intensity (TI) or the more-recent methods temporal dominance of sensations (TDS) and temporal check-all-that-apply (TCATA) are used to account for the dynamic and time-related aspects of flavor perception. Direct injection mass spectrometry (DIMS) techniques that measure in real time aroma compounds directly in the nose (nosespace), aimed at obtaining data that reflect the pattern of aroma release in real time during food consumption and supposed to be representative of perception, have been developed over the last 25 years. Examples obtained with MS operated in chemical ionization mode at atmospheric or sub-atmospheric pressure (atmospheric pressure chemical ionization APCI or proton-transfer reaction PTR) are given, with emphases on studies conducted with simultaneous dynamic sensory evaluation. Inter-individual variations in terms of aroma release and their relevance for understanding flavor perception are discussed as well as the evidenced cross-modal interactions.

Optical characterisation of two novel myopia control spectacle lenses

PURPOSE

To quantify the amount of myopic defocus, contrast modulation and other optical characteristics of two novel spectacle lenses (MiYOSMART by Hoya and Stellest by Essilor) with the inclusion of lenslets in their designs were investigated computationally and experimentally. This paper examined the hypothesis that despite the non-coaxial nature of the optics, image degradation will exist due to the fragmented nature of the base optic when imaging through the lens regions populated by lenslets.

METHODS

Optical power was evaluated by computing wavefront vergence and curvature from wavefront slope measured with the Optocraft aberrometer within 1.0 and 6.0 mm apertures across MiYOSMART hexagons and Stellest rings. Point-spread functions (PSFs) were computed using physical (wave) optics and geometrical ray optics principles, and compared with experimental measurements using a 4f optical system. Simulated retinal images and modulation transfer functions (MTFs) were computed from PSF-derived optical transfer functions (OTFs).

RESULTS

Mean lenslet power in MiYOSMART was +3.95 ± 0.10 D through the hexagons and +6.00 ± 0.15 D in Stellest in rings 1-5 and decreased by 0.42 D/ring reaching 3.50 D in the final one. Stellest lenslets included up to -0.015 microns of primary spherical aberration. PSFs and retinal images revealed simultaneous contributions of the base optic and lenslets. MTFs showed a decrease in contrast at low (1-10 c/deg) spatial frequencies (SFs) comparable to 0.25 D of defocus, and retention of diminished levels of contrast at higher SFs.

CONCLUSIONS

Varying sagittal power and consistent curvature power across the lenslets is an identifying signature of the novel non-coaxial lens design included in both spectacle lenses. Lenslet array structure itself plays a significant role in determining image characteristics. For both lenses, the blur created by the fragmented base optic contributes to the image quality. The reduced MTFs over a wide range of spatial frequencies result in lowered image contrast.

Balancing Trade-Offs Imposed by Growth Media and Mass Spectrometry for Bacterial Exometabolomics

The bacterial exometabolome consists of a vast array of specialized metabolites, many of which are only produced in response to specific environmental stimuli. For this reason, it is desirable to control the extracellular environment with a defined growth medium composed of pure ingredients. However, complex (undefined) media are expected to support the robust growth of a greater variety of microorganisms than defined media. Here, we investigate the trade-offs inherent to a range of complex and defined solid media for the growth of soil microorganisms, production of specialized metabolites, and detection of these compounds using direct infusion mass spectrometry. We find that complex media support growth of more soil microorganisms, as well as allowing for the detection of more previously discovered natural products as a fraction of total m/z features detected in each sample. However, the use of complex media often caused mass spectrometer injection failures and poor-quality mass spectra, which in some cases resulted in over a quarter of samples being removed from analysis. Defined media, while more limiting in growth, generated higher quality spectra and yielded more m/z features after background subtraction. These results inform future exometabolomic experiments requiring a medium that supports the robust growth of many soil microorganisms. IMPORTANCE Bacteria are capable of producing and secreting a rich diversity of specialized metabolites. Yet, much of their exometabolome remains hidden due to challenges associated with eliciting specialized metabolite production, labor-intensive sample preparation, and time-consuming analysis techniques. Using our versatile three-dimensional (3D)-printed culturing platform, SubTap, we demonstrate that rapid exometabolomic data collection from a diverse set of environmental bacteria is feasible. We optimized our platform by surveying Streptomyces isolated from soil on a variety of media types to assess viability, degree of specialized metabolite production, and compatibility with downstream LESA-DIMS analysis. Ultimately, this will enable data-rich experimentation, allowing for a better understanding of bacterial exometabolomes.

[Myopia treatment and prophylaxis with defocus incorporated multiple segments spectacle lenses]

Excessive axial eye growth in children and adolescents leads to progressive myopia and can result in severe ocular diseases in adulthood. Various strategies have already been developed to inhibit progression of myopia. The novel single vision lens presented in this article features the defocus incorporated multiple segments (DIMS) technology and adds an easy to use, noninvasive option to the portfolio of myopia treatment. Initial studies showed promising results with only a very low side effect profile.

Optical and imaging properties of a novel multi-segment spectacle lens designed to slow myopia progression

PURPOSE

High sampling density optical metrology combined with pupil- and image-plane numerical analyses were applied to evaluate a novel spectacle lens containing multiple small zones designed to slow myopia progression.

METHODS

High-resolution aberrometry (ClearWave, www.lumetrics.com) was used to sample wavefront slopes of a novel spectacle lens, Defocus Incorporated Multiple Segments (DIMS) (www.hoya.com), incorporating many small, positive-powered lenslets in its periphery. Using wavefront slope and error maps, custom MATLAB software ('Indiana Wavefront Analyzer') was used to compute image-plane point-spread functions (PSF), modulation transfer functions (MTF), simulated images and power distributions created by the dual-focus optic for different pupil sizes and target vergences.

RESULTS

Outside of a central 10 mm zone containing single distance optical power, a hexagonal array of small 1 mm lenslets with nearest-neighbour separations of 0.5 mm were distributed over the lens periphery. Sagittal and curvature-based measures of optical power imperfectly captured the consistent +3.50 D add produced by the lenslets. Image plane simulations revealed multiple PSFs and poor image quality at the lenslet focal plane. Blur at the distance optic focal plane was consistent with a combination of diffraction blur from the distance optic and the approximately +3.50 D of defocus from the 1 mm diameter near optic zones.

CONCLUSION

Converging the defocused beams generated by the multiple small (1 mm diameter) lenslets to a blurred image at the distance focal plane produced a blur magnitude determined by the small lenslet diameter and not the overall pupil diameter. The distance optic located in between the near-add lenslets determines the limits of the optical quality achievable by the lens. When compared to the optics of a traditional concentric-zone dual-focus contact lens, the optics of the DIMS lens generates higher-contrast images at low spatial frequencies (<7 cycles per degree), but lower-contrast at high spatial frequencies.

Assessing the Pre-Analytical Stability of Small-Molecule Metabolites in Cerebrospinal Fluid Using Direct-Infusion Metabolomics

Metabolomics studies aiming to find biomarkers frequently make use of historical or multicenter cohorts. These samples often have different pre-analytical conditions that potentially affect metabolite concentrations. We studied the effect of different storage conditions on the stability of small-molecule metabolites in cerebrospinal fluid to aid a reliable interpretation of metabolomics data. Three cerebrospinal fluid pools were prepared from surplus samples from the Amsterdam Dementia Cohort biobank. Aliquoted pools were exposed to different storage conditions to assess the temperature and freeze/thaw stability before final storage at −80 °C: storage up to four months at −20 °C and up to one week at either 5–8 °C or 18–22 °C and exposure to up to seven freeze/thaw cycles. Direct-infusion high-resolution mass spectrometry was performed, resulting in the identification of 1852 m/z peaks. To test the storage stability, principal component analyses, repeated measures analysis of variance, Kruskal–Wallis tests, and fold change analyses were performed, all demonstrating that small-molecule metabolites in the cerebrospinal fluid (CSF) are relatively unaffected by 1–3 freeze/thaw cycles, by storage at −20 °C up to two months, by storage at 5–8 °C for up to 72 h, or by storage at 18–22 °C for up to 8 h. This suggests that these differences do not affect the interpretation of potential small-molecule biomarkers in multicenter or historical cohorts and implies that these cohorts are suitable for biomarker studies.

Direct-infusion based metabolomics unveils biochemical profiles of inborn errors of metabolism in cerebrospinal fluid

BACKGROUND

For inborn errors of metabolism (IEM), metabolomics is performed for three main purposes: 1) development of next generation metabolic screening platforms, 2) identification of new biomarkers in predefined patient cohorts and 3) for identification of new IEM. To date, plasma, urine and dried blood spots are used. We anticipate that cerebrospinal fluid (CSF) holds additional - valuable - information, especially for IEM with neurological involvement. To expand metabolomics to CSF, we here tested whether direct-infusion high-resolution mass spectrometry (DI-HRMS) based non-quantitative metabolomics could correctly capture the biochemical profile of patients with an IEM in CSF.

METHODS

Eleven patient samples, harboring eight different IEM, and thirty control samples were analyzed using DI-HRMS. First we assessed whether the biochemical profile of the control samples represented the expected profile in CSF. Next, each patient sample was assigned a 'most probable diagnosis' by an investigator blinded for the known diagnoses of the patients.

RESULTS

the biochemical profile identified using DI-HRMS in CSF samples resembled the known profile, with - among others - the highest median intensities for mass peaks annotated with glucose, lactic acid, citric acid and glutamine. Subsequent analysis of patient CSF profiles resulted in correct 'most probable diagnoses' for all eleven patients, including non-ketotic hyperglycinaemia, propionic aciduria, purine nucleoside phosphorylase deficiency, argininosuccinic aciduria, tyrosinaemia type I, hyperphenylalaninemia and hypermethioninaemia.

CONCLUSION

We here demonstrate that DI-HRMS based non-quantitative metabolomics accurately captures the biochemical profile of this set of patients in CSF, opening new ways for using metabolomics in CSF in the metabolic diagnostic laboratory.

Direct Infusion Based Metabolomics Identifies Metabolic Disease in Patients' Dried Blood Spots and Plasma

In metabolic diagnostics, there is an emerging need for a comprehensive test to acquire a complete view of metabolite status. Here, we describe a non-quantitative direct-infusion high-resolution mass spectrometry (DI-HRMS) based metabolomics method and evaluate the method for both dried blood spots (DBS) and plasma. 110 DBS of 42 patients harboring 23 different inborn errors of metabolism (IEM) and 86 plasma samples of 38 patients harboring 21 different IEM were analyzed using DI-HRMS. A peak calling pipeline developed in R programming language provided Z-scores for ~1875 mass peaks corresponding to ~3835 metabolite annotations (including isomers) per sample. Based on metabolite Z-scores, patients were assigned a ‘most probable diagnosis’ by an investigator blinded for the known diagnoses of the patients. Based on DBS sample analysis, 37/42 of the patients, corresponding to 22/23 IEM, could be correctly assigned a ‘most probable diagnosis’. Plasma sample analysis, resulted in a correct ‘most probable diagnosis’ in 32/38 of the patients, corresponding to 19/21 IEM. The added clinical value of the method was illustrated by a case wherein DI-HRMS metabolomics aided interpretation of a variant of unknown significance (VUS) identified by whole-exome sequencing. In summary, non-quantitative DI-HRMS metabolomics in DBS and plasma is a very consistent, high-throughput and nonselective method for investigating the metabolome in genetic disease.

Metabolomics Discovers Early-Response Metabolic Biomarkers that Can Predict Chronic Reproductive Fitness in Individual Daphnia magna

Chemical risk assessment remains entrenched in chronic toxicity tests that set safety thresholds based on animal pathology or fitness. Chronic tests are resource expensive and lack mechanistic insight. Discovering a chemical's mode-of-action can in principle provide predictive molecular biomarkers for a toxicity endpoint. Furthermore, since molecular perturbations precede pathology, early-response molecular biomarkers may enable shorter, more resource efficient testing that can predict chronic animal fitness. This study applied untargeted metabolomics to attempt to discover early-response metabolic biomarkers that can predict reproductive fitness of Daphnia magna, an internationally-recognized test species. First, we measured the reproductive toxicities of cadmium, 2,4-dinitrophenol and propranolol to individual Daphnia in 21-day OECD toxicity tests, then measured the metabolic profiles of these animals using mass spectrometry. Multivariate regression successfully discovered putative metabolic biomarkers that strongly predict reproductive impairment by each chemical, and for all chemicals combined. The non-chemical-specific metabolic biomarkers were then applied to metabolite data from Daphnia 24-h acute toxicity tests and correctly predicted that significant decreases in reproductive fitness would occur if these animals were exposed to cadmium, 2,4-dinitrophenol or propranolol for 21 days. While the applicability of these findings is limited to three chemicals, they provide proof-of-principle that early-response metabolic biomarkers of chronic animal fitness can be discovered for regulatory toxicity testing.

Fast Profiling of Natural Pigments in Different Spirulina (Arthrospira platensis) Dietary Supplements by DI-FT-ICR and Evaluation of their Antioxidant Potential by Pre-Column DPPH-UHPLC Assay

Arthrospira platensis, better known as Spirulina, is one of the most important microalgae species. This cyanobacterium possesses a rich metabolite pattern, including high amounts of natural pigments. In this study, we applied a combined strategy based on Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and Ultra High-Performance Liquid Chromatography (UHPLC) for the qualitative/quantitative characterization of Spirulina pigments in three different commercial dietary supplements. FT-ICR was employed to elucidate the qualitative profile of Spirulina pigments, in both direct infusion mode (DIMS) and coupled to UHPLC. DIMS showed to be a very fast (4 min) and accurate (mass accuracy ≤ 0.01 ppm) tool. 51 pigments were tentatively identified. The profile revealed different classes, such as carotenes, xanthophylls and chlorophylls. Moreover, the antioxidant evaluation of the major compounds was assessed by pre-column reaction with the DPPH radical followed by fast UHPLC-PDA separation, highlighting the contribution of single analytes to the antioxidant potential of the entire pigment fraction. β-carotene, diadinoxanthin and diatoxanthin showed the highest scavenging activity. The method took 40 min per sample, comprising reaction. This strategy could represent a valid tool for the fast and comprehensive characterization of Spirulina pigments in dietary supplements, as well as in other microalgae-based products.

Defining the Baseline and Oxidant Perturbed Lipidomic Profiles of Daphnia magna

Recent technological advancement has enabled the emergence of lipidomics as an important tool for assessing molecular stress, one which has yet to be assessed fully as an approach in an environmental toxicological context. Here we have applied a high-resolution, non-targeted, nanoelectrospray ionisation (nESI) direct infusion mass spectrometry (DIMS) technique to assess the effects of oxidative stress to Daphnia magna both in vitro (air exposure of daphniid extracts) and in vivo (Cu²⁺ exposure). Multivariate and univariate statistical analyses were used to distinguish any perturbations including oxidation to the D. magna baseline lipidome. This approach enabled the putative annotation of the baseline lipidome of D. magna with 65% of the lipid species discovered previously not reported. In vitro exposure of lipid extracts to air, primarily to test the methodology, revealed a significant perturbation to this baseline lipidome with detectable oxidation of peaks, in most cases attributed to single oxygen addition. Exposure of D. magna to Cu²⁺ in vivo also caused a significant perturbation to the lipidome at an environmentally relevant concentration of 20 µg/L. This nESI DIMS approach has successfully identified perturbations and oxidative modifications to the D. magna lipidome in a high-throughput manner, highlighting its suitability for environmental lipidomic studies.

Application of Passive Sampling to Characterise the Fish Exometabolome

The endogenous metabolites excreted by organisms into their surrounding environment, termed the exometabolome, are important for many processes including chemical communication. In fish biology, such metabolites are also known to be informative markers of physiological status. While metabolomics is increasingly used to investigate the endogenous biochemistry of organisms, no non-targeted studies of the metabolic complexity of fish exometabolomes have been reported to date. In environmental chemistry, Chemcatcher^® (Portsmouth, UK) passive samplers have been developed to sample for micro-pollutants in water. Given the importance of the fish exometabolome, we sought to evaluate the capability of Chemcatcher^® samplers to capture a broad spectrum of endogenous metabolites excreted by fish and to measure these using non-targeted direct infusion mass spectrometry metabolomics. The capabilities of C18 and styrene divinylbenzene reversed-phase sulfonated (SDB-RPS) Empore™ disks for capturing non-polar and polar metabolites, respectively, were compared. Furthermore, we investigated real, complex metabolite mixtures excreted from two model fish species, rainbow trout (Oncorhynchus mykiss) and three-spined stickleback (Gasterosteus aculeatus). In total, 344 biological samples and 28 QC samples were analysed, revealing 646 and 215 m/z peaks from trout and stickleback, respectively. The measured exometabolomes were principally affected by the type of Empore™ (Hemel Hempstead, UK) disk and also by the sampling time. Many peaks were putatively annotated, including several bile acids (e.g., chenodeoxycholate, taurocholate, glycocholate, glycolithocholate, glycochenodeoxycholate, glycodeoxycholate). Collectively these observations show the ability of Chemcatcher^® passive samplers to capture endogenous metabolites excreted from fish.

Metabolomic Analysis of Campylobacter jejuni by Direct-Injection Electrospray Ionization Mass Spectrometry

Direct-injection mass spectrometry (DIMS) is a means of rapidly obtaining metabolomic phenotype data in both prokaryotes and eukaryotes. Given our generally poor understanding of Campylobacter metabolism, the high-throughput and relatively simple sample preparation of DIMS has made this an attractive technique for metabolism-related studies and hypothesis generation, especially when attempting to analyze metabolic mutants with no clear phenotype. Here we describe a metabolomic fingerprinting approach with sampling and extraction methodologies optimized for direct-injection electrospray ionization mass spectrometry (ESI-MS), which we have used as a means of comparing wild-type and isogenic mutant strains of C. jejuni with various metabolic blocks.

Is online information on ecstasy tablet content safe?

BACKGROUND AND AIMS

In recent years, the prevalence of ecstasy use has increased in most European countries. Users can acquire information on ecstasy tablet composition through the internet. This study compares online information from two websites, Pillreports and Partyflock, to the validated Dutch Drugs Information and Monitoring System (DIMS) database, and aims to measure its accuracy and potential danger or value.

DESIGN, SETTING, PARTICIPANTS

The drug-related information posted on Pillreports.net and Partyflock.nl between 1 January 2014 and 31 December 2015 was investigated for accuracy and several information characteristics such as picture inclusion and dose range inclusion. In total, 471 informatory statements on ecstasy tablet content were analysed relative to the Dutch ecstasy market.

MEASUREMENTS

Informatory statements on the content of specific ecstasy tablets were scored as 'too high' or 'too low' if their concentrations deviated > 10 mg from the entries in the DIMS database within a 12-week time-frame, and scored as 'dangerous' if their concentration was > 40 mg too low. Unreported substances were scored as 'dangerous' if listed as an illegal or dangerous substance in the DIMS database and if present in relevant quantities. Also scored were the report characteristics 'picture inclusion', 'spread inclusion' and 'website source', which were tested for their association with report safety/danger.

FINDINGS

On average, reports on ecstasy tablets from Pillreports and Partyflock show concentrations which are 10.6 mg too high [95% confidence interval (CI) = 6.7-14.4]. Qualitatively, 39.7% of the reports scored as 'too high' (95% CI = 35.2-44.4), 17.6% scored as 'too low' (95% CI = 14.0-21.2) and 15.5% had 'unreported substances' (95% CI = 12.3-18.9), resulting overall in 15.3% of the reports being scored as 'dangerous' (95% CI = 11.9-18.5). The report characteristic 'spread inclusion' associated inversely with report danger [Exp(b) = 0.511, 95% CI = 0.307-0.850, P = 0.01].

CONCLUSION

Information from the popular Pillreports and Partyflock websites tends to overestimate 3,4-methylenedioxymethamphetamine (MDMA) concentrations in ecstasy tablets. In addition, 15.3% of the reports omit the relevant concentration spread, fail to report additional illegal or dangerous substances contained in the tablets or underestimate MDMA concentration by > 40 mg.

Gene expression and metabolic responses of HepG2/C3A cells exposed to flame retardants and dust extracts at concentrations relevant to indoor environmental exposures

Humans are routinely exposed to mixtures of flame retardants (FRs) from multiple sources including indoor dust. As a model to explore the potential effects of FR exposure from indoor dust on human health, the molecular responses of human hepatoma cells (HepG2/C3A cells) to a defined mixture of FRs and to a dust extract were investigated using multiple non-targeted omics approaches. A solvent extract of an indoor dust standard reference material SRM2585 was used as the surrogate dust sample, while a mixture of four FRs (TCEP, TCIPP, TDCIPP and HBCD) was used to mimic the FR mixture in the indoor dust. Cytotoxicity tests indicated there were no significant changes to cell viability or cell integrity after a 24- or 72-h exposure of HepG2/C3A cells to the FR mixture or to the dust extract. However, transcriptomics revealed changes in gene expression associated with the metabolism of xenobiotics (e.g. CYP1A1, CYP1A2, CYP2B6) in the dust extract group but not in the FR mixture group after a 72-h exposure. Few metabolic or lipidomic changes were detected in response to either the FR mixture or to the dust extract group. Given that the dust extract contained components that elicited a biological response, in contrast to the lack of response induced by the FR mixture, our findings suggest that the most likely causes of the molecular responses to indoor dust exposure lie in components other than the four FRs investigated, e.g. caused by PAHs or PCBs.

Improved Differential Ion Mobility Separations Using Linked Scans of Carrier Gas Composition and Compensation Field

Differential ion mobility spectrometry (DIMS) separates ions based on differences in their mobilities in low and high electric fields. When coupled to mass spectrometric analyses, DIMS has the ability to improve signal-to-background by eliminating isobaric and isomeric compounds for analytes in complex mixtures. DIMS separation power, often measured by resolution and peak capacity, can be improved through increasing the fraction of helium in the nitrogen carrier gas. However, because the mobility of ions is higher in helium, a greater number of ions collide with the DIMS electrodes or housing, yielding losses in signal intensity. To take advantage of the benefits of helium addition on DIMS separations and reduce ion losses, linked scans were developed. In a linked scan the helium content of the carrier gas is reduced as the compensation field is increased. Linked scans were compared with conventional compensation field scans with constant helium content for the protein ubiquitin and a tryptic digest of bovine serum albumin (BSA). Linked scans yield better separation of ubiquitin charge states and enhanced peak capacities for the analysis of BSA compared with compensation field scans with constant helium carrier gas percentages. Linked scans also offer improved signal intensity retention in comparison to compensation field scans with constant helium percentages in the carrier gas.

Genetic variants associated with sleep disorders

OBJECTIVE

The diagnostic boundaries of sleep disorders are under considerable debate. The main sleep disorders are partly heritable; therefore, defining heritable pathophysiologic mechanisms could delineate diagnoses and suggest treatment. We collected clinical data and DNA from consenting patients scheduled to undergo clinical polysomnograms, to expand our understanding of the polymorphisms associated with the phenotypes of particular sleep disorders.

METHODS

Patients at least 21 years of age were recruited to contribute research questionnaires, and to provide access to their medical records, saliva for deoxyribonucleic acid (DNA), and polysomnographic data. From these complex data, 38 partly overlapping phenotypes were derived indicating complaints, subjective and objective sleep timing, and polysomnographic disturbances. A custom chip was used to genotype 768 single-nucleotide polymorphisms (SNPs). Additional assays derived ancestry-informative markers (eg, 751 participants of European ancestry). Linear regressions controlling for age, gender, and ancestry were used to assess the associations of each phenotype with each of the SNPs, highlighting those with Bonferroni-corrected significance.

RESULTS

In peroxisome proliferator-activated receptor gamma, coactivator 1 beta (PPARGC1B), rs6888451 was associated with several markers of obstructive sleep apnea. In aryl hydrocarbon receptor nuclear translocator-like (ARNTL), rs10766071 was associated with decreased polysomnographic sleep duration. The association of rs3923809 in BTBD9 with periodic limb movements in sleep was confirmed. SNPs in casein kinase 1 delta (CSNK1D rs11552085), cryptochrome 1 (CRY1 rs4964515), and retinoic acid receptor-related orphan receptor A (RORA rs11071547) were less persuasively associated with sleep latency and time of falling asleep.

CONCLUSIONS

SNPs associated with several sleep phenotypes were suggested, but due to risks of false discovery, independent replications are needed before the importance of these associations can be assessed, followed by investigation of molecular mechanisms.

Differential ion mobility spectrometry coupled to tandem mass spectrometry enables targeted leukemia antigen detection

Differential ion mobility spectrometry (DIMS) can be used as a filter to remove undesired background ions from reaching the mass spectrometer. The ability to use DIMS as a filter for known analytes makes DIMS coupled to tandem mass spectrometry (DIMS-MS/MS) a promising technique for the detection of cancer antigens that can be predicted by computational algorithms. In experiments using DIMS-MS/MS that were performed without the use of high-performance liquid chromatography (HPLC), a predicted model antigen, GLR (FLSSANEHL), was detected at a concentration of 10 pM (20 amol) in a mixture containing 94 competing model peptide antigens, each at a concentration of 1 μM. Without DIMS filtering, the GLR peptide was undetectable in the mixture even at 100 nM. Again, without using HPLC, DIMS-MS/MS was used to detect 2 of 3 previously characterized antigens produced by the leukemia cell line U937.A2. Because of its sensitivity, a targeted DIMS-MS/MS methodology can likely be used to probe for predicted cancer antigens from cancer cell lines as well as human tumor samples.

The development and validation of a fast and robust dried blood spot based lipid profiling method to study infant metabolism

Early life exposures and metabolic programming are associated with later disease risk. In particular lipid metabolism is thought to play a key role in the development of the metabolic syndrome and insulin resistance in later life. Investigative studies of metabolic programming are limited by the ethics and practicalities of sample collection in small infants. Dried blood spots on filter paper, derived from heel pricks are considered as the most suitable option for this age group. We validated a novel lipid profiling method, based on high resolution mass spectrometry to successfully determine the lipid composition of infants using dried blood spots. The spotting and air drying of blood on paper has noticeable effects on many of the lipids, leading to lipid oxidation and hydrolysis, which demand careful interpretation of the obtained data. We compared the lipid profiles from plasma or whole blood samples and the results from dried blood spots to determine if these revealed the same inter-subject differences. The results from dried blood spots were no less reproducible than other lipid profiling methods which required comparatively larger sample volumes. Therefore, lipid profiles obtained from dried blood spots can be successfully used to monitor infancy lipid metabolism and we show significant differences in the lipid metabolism of infants at age 3 versus 12 months.

Metabolomic analysis of the food-borne pathogen Campylobacter jejuni: application of direct injection mass spectrometry for mutant characterisation

Campylobacter jejuni is the most frequent cause of human food-borne bacterial gastroenteritis but its physiology and biochemistry are poorly understood. Only a few amino-acids can be catabolised and these are known to be important for host colonization. Here we have established methods for rapid high throughput analyses of global metabolism in C. jejuni using direct injection mass spectrometry (DIMS) to compare metabolite fingerprints of wild-type and mutant strains. Principal component analyses show that the metabolic fingerprint of mutants that have a genomic deletion in genes for key amino-acid catabolic enzymes (either sdaA, serine dehydratase; aspA, aspartase or aspB, aspartate:glutamate transaminase) can easily be distinguished from the isogenic parental strain. Assignment of putative metabolites showed predictable changes directly associated with the particular metabolic lesion in these mutants as well as more extensive changes in the aspA mutant compared to the sdaA or aspB strains. Further analyses of a cj0150c mutant strain, which has no obvious phenotype, suggested a role for Cj0150 in the conversion of cystathionine to homocysteine. Our results show that DIMS is a useful technique for probing the metabolism of this important pathogen and may help in assigning function to genes encoding novel enzymes with currently unknown metabolic roles.

The role of metabolomics in neonatal and pediatric laboratory medicine

Metabolomics consists of the quantitative analysis of a large number of low molecular mass metabolites involving substrates or products in metabolic pathways existing in all living systems. The analysis of the metabolic profile detectable in a human biological fluid allows to instantly identify changes in the composition of endogenous and exogenous metabolites caused by the interaction between specific physiopathological states, gene expression, and environment. In pediatrics and neonatology, metabolomics offers new encouraging perspectives for the improvement of critically ill patient outcome, for the early recognition of metabolic profiles associated with the development of diseases in the adult life, and for delivery of individualized medicine. In this view, nutrimetabolomics, based on the recognition of specific cluster of metabolites associated with nutrition and pharmacometabolomics, based on the capacity to personalize drug therapy by analyzing metabolic modifications due to therapeutic treatment may open new frontiers in the prevention and in the treatment of pediatric and neonatal diseases. This review summarizes the most relevant results published in the literature on the application of metabolomics in pediatric and neonatal clinical settings. However, there is the urgent need to standardize physiological and preanalytical variables, analytical methods, data processing, and result presentation, before establishing the definitive clinical value of results.