A case series exploring the human milk polyclonal IgA1 response to repeated SARS-CoV-2 vaccinations by LC–MS based fab profiling

Introduction: Upon vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) humans will start to produce antibodies targeting virus specific antigens that will end up in circulation. In lactating women such antibodies will also end up in breastmilk, primarily in the form of secretory immunoglobulin A1 (SIgA1), the most abundant immunoglobulin (Ig) in human milk. Here we set out to investigate the SIgA1 clonal repertoire response to repeated SARS-CoV-2 vaccination, using a LC–MS fragment antigen-binding (Fab) clonal profiling approach.Methods: We analyzed the breastmilk of six donors from a larger cohort of 109 lactating mothers who received one of three commonly used SARS-CoV-2 vaccines. We quantitatively monitored the SIgA1 Fab clonal profile over 16 timepoints, from just prior to the first vaccination until 15  days after the second vaccination.Results: In all donors, we detected a population of 89–191 vaccine induced clones. These populations were unique to each donor and heterogeneous with respect to individual clonal concentrations, total clonal titer, and population size. The vaccine induced clones were dominated by persistent clones (68%) which came up after the first vaccination and were retained or reoccurred after the second vaccination. However, we also observe transient SIgA1 clones (16%) which dissipated before the second vaccination, and vaccine induced clones which uniquely emerged only after the second vaccination (16%). These distinct populations were observed in all analyzed donors, regardless of the administered vaccine.Discussion: Our findings suggest that while individual donors have highly unique human milk SIgA1 clonal profiles and a highly personalized SIgA1 response to SARS-CoV-2 vaccination, there are also commonalities in vaccine induced responses

Evolution reveals a glutathione-dependent mechanism of 3-hydroxypropionic acid tolerance

Biologically produced 3-hydroxypropionic acid (3HP) is a potential source for sustainable acrylates and can also find direct use as monomer in the production of biodegradable polymers. For industrial scale production there is a need for robust cell factories tolerant to high concentration of 3HP, preferably at low pH. Through adaptive laboratory evolution we selected S. cerevisiae strains with improved tolerance to 3HP at pH 3.5. Genome sequencing followed by functional analysis identified the causal mutation in SFA1 gene encoding S-(hyclroxymerhyl)glutathione dehydrogenase. Based on our findings, we propose that 3HP toxicity is mediated by 3-hydroxypropionic aldehyde (reuterin ) and that glutathione-dependent reactions are used for reuterin detoxification. The identified molecular response to 3HP and reuterin may well be a general mechanism for handling resistance to organic acid and aldehydes by living cells. (C) 2014 International Metabolic Engineering Society Published by Elsevier Inc. On behalf of International Metabolic Engineering Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/

Framework of synchromodal transportation problems

Though literature reviews of synchromodal transportation exist, no generalised mathematical model of these problems has been found yet. In this paper such a framework is introduced, by which mathematical models described in literature on synchromodal transportation problems can be classified. This framework should help researchers and developers to find solution methodologies that are commonly used in their problem instance and to grasp characteristics of the models and cases in a compact way, enabling easy classification, comparison and insight in complexity

The influence of a maternal vegan diet on carnitine and vitamin B2 concentrations in human milk

BackgroundThe maternal diet greatly influences the nutritional composition of human milk. With the rise of vegan diets by lactating mothers, there are concerns about the nutritional adequacy of their milk. Two important nutrients, vitamin B2 and carnitine, are mostly ingested via animal products.ObjectiveWe investigated the influence of a vegan diet on the vitamin B2 and carnitine concentrations in milk and serum of lactating women.MethodsIn this case–control study, 25 lactating mothers following an exclusive vegan diet were comparted to 25 healthy lactating mothers with an omnivorous diet without use of supplements. High-performance liquid chromatography and liquid chromatography–tandem mass spectrometry were used to measure vitamin B2 and carnitine concentrations, respectively. A linear regression model was used to determine differences in human milk and serum concentrations between study groups.ResultsVitamin B2 concentrations in human milk and serum did not differ between study groups. While the human milk free carnitine (C0) and acetyl carnitine (C2) concentrations did not differ between study groups, serum carnitine concentrations were lower in participants following a vegan diet than in omnivorous women (p < 0.0001).ConclusionA maternal vegan diet did not affect human milk concentration of vitamin B2 and carnitine. Breastfed infants of mothers following an exclusive vegan diet therefore are likely not at increased risk of developing a vitamin B2 or carnitine deficiency

Improving comparability between microarray probe signals by thermodynamic intensity correction

Signals from different oligonucleotide probes against the same target show great variation in intensities. However, detection of differences along a sequence e.g. to reveal intron/exon architecture, transcription boundary as well as simple absent/present calls depends on comparisons between different probes. It is therefore of great interest to correct for the variation between probes. Much of this variation is sequence dependent. We demonstrate that a thermodynamic model for hybridization of either DNA or RNA to a DNA microarray, which takes the sequence-dependent probe affinities into account significantly reduces the signal fluctuation between probes targeting the same gene transcript. For a test set of tightly tiled yeast genes, the model reduces the variance by up to a factor ∼1/3. As a consequence of this reduction, the model is shown to yield a more accurate determination of transcription start sites for a subset of yeast genes. In another application, we identify present/absent calls for probes hybridized to the sequenced Escherichia coli strain O157:H7 EDL933. The model improves the correct calls from 85 to 95% relative to raw intensity measures. The model thus makes applications which depend on comparisons between probes aimed at different sections of the same target more reliable

Lab on a stick: multi-analyte cellular assays in a microfluidic dipstick

A new microfluidic concept for multi-analyte testing in a dipstick format is presented, termed “Lab-on-a-Stick”, that combines the simplicity of dipstick tests with the high performance of microfluidic devices. Lab-on-a-Stick tests are ideally suited to analysis of particulate samples such as mammalian or bacterial cells, and capable of performing multiple different parallel microfluidic assays when dipped into a single sample with results recorded optically. The utility of this new diagnostics format was demonstrated by performing three types of multiplex cellular assays that are challenging to perform in conventional dipsticks: 1) instantaneous ABO blood typing; 2) microbial identification; and 3) antibiotic minimum inhibitory (MIC) concentration measurement. A pressure balance model closely predicted the superficial flow velocities in individual capillaries, that were overestimated by up to one order of magnitude by the Lucas-Washburn equation conventionally used for wicking in cylindrical pores. Lab-on-a-stick provides a cost-effective, simple, portable and flexible multiplex platform for a range of assays, and will deliver a new generation of advanced yet affordable point-of-care tests for global diagnostics