Legalization and retail availability of recreational marijuana and adolescent use in schools.

Legalization of use and retail sales of recreational marijuana in U.S. states and the associated potential increase in access to marijuana and normalization of its use by adults could lead to increased use by adolescents. Studies have found that states with legal recreational marijuana have higher rates of adolescent use and frequency of use compared to states without legal use. We examined changes in student office discipline referrals (ODRs) for substance use offenses in Oregon middle and high schools before and after the legalization of recreational marijuana relative to comparison schools in other states. We found that rates of substance use related ODRs in middle schools increased by 0.14 per 100 students (30% of the mean) with legalization relative to comparison schools. This increase was moderated by the presence of a marijuana outlet within one mile of the school. We found no statistically discernible changes in high school ODRs. Marijuana use in adolescence has been linked to negative health and social consequences, including academic problems, mental health issues, and impaired driving. Potential adverse impact on adolescents and investments in school-based prevention programs could be important considerations for policymakers and public health officials when evaluating marijuana legalization.

Biology of human milk oligosaccharides: From basic science to clinical evidence.

Human milk oligosaccharides (HMOs) have been researched by scientists for over 100 years, driven by the substantial evidence for the nutritional and health benefits of mother's milk. Yet research has truly bloomed during the last decade, thanks to progress in biotechnology, which has allowed the production of large amounts of bona fide HMOs. The availability of HMOs has been particularly crucial for the renewed interest in HMO research because of the low abundance or even absence of HMOs in farmed animal milk. This interest is reflected in the increasing number of original research publications and reviews on HMOs. Here, we provide an overview and critical discussion on structure-function relations of HMOs that highlight why they are such interesting and important components of human milk. Clinical observations in breastfed infants backed by basic research from animal models provide guidance as to what physiological roles for HMOs are to be expected. From an evidence-based nutrition viewpoint, we discuss the current data supporting the clinical relevance of specific HMOs based on randomised placebo-controlled clinical intervention trials in formula-fed infants.

Human milk oligosaccharides, infant growth, and adiposity over the first 4 months of lactation.

BACKGROUND: The relationship between human milk oligosaccharides (HMOs) and infant growth and adiposity is not fully understood and comprehensive studies are missing from the current literature. METHODS: We screened and recruited 370 healthy, pregnant women and their infants from seven European countries. Breastmilk samples were collected using standardized procedures at six time points over 4 months, as were infant parameters. Correlations and associations between HMO area under the curve, anthropometric data, and fat mass at 4 months were tested. RESULTS: Lacto-N-neotetraose had a negative correlation with the change in length (rs = -0.18, P = 0.02). Sialyllacto-N-tetraose c (LSTc) had a positive correlation with weight for length (rs = 0.19, P = 0.015). Infants at the 25th upper percentile were fed milk higher in 3'-sialyllactose and LSTc (P = 0.017 and P = 0.006, respectively) compared to the lower 25th percentile of the weight-for-length z-score gain over 4 months of lactation. No significant associations between growth and body composition and Lewis or secretor-dependent HMOs like 2'-fucosyllactose were identified. CONCLUSIONS: Changes in the HMO composition of breastmilk during the first 4 months appear to have little influence on infant growth and body composition in this cohort of healthy mothers and infants. IMPACT: Modest associations exist between individual HMO and infant growth outcomes at least in healthy growing populations. Our study provides a comprehensive investigation of associations between all major HMO and infant growth and adiposity including several time points. Certain groups of HMOs, like the sialylated, may be associated with adiposity during the first months of lactation. HMO may modulate the risk of future metabolic disease. Future population studies need to address the role of specific groups of HMOs in the context of health and disease to understand the long-term impact.

Concentrations of oligosaccharides in human milk and child growth.

BACKGROUND: The relationship between human milk oligosaccharides (HMO) and child growth has been investigated only insufficiently with ambiguous results. Therefore, this study examines potential influencing factors of HMO concentrations and how HMO are associated with child growth parameters. METHODS: Milk samples from the German LIFE Child cohort of healthy children were analyzed for 9 HMO. Putative associations with maternal and child cofactors and child height, head circumference and BMI between 3 months and 7 years of age were examined. Secretor status, defined as the presence of 2'-fucosyllactose, was investigated for associations with infant outcomes. RESULTS: Our population consisted of 21 (14.7%) non-secretor and 122 (85.3%) secretor mothers. Maternal age was significantly associated with higher 3'SL concentrations; gestational age was associated with LNT, 6'SL and LNFP-I. Pre-pregnancy BMI was negatively associated with LNnT only in non-secretors. The growth velocity of non-secretors' children was inversely associated with LNnT at 3 months to 1 year (R = 0.95 [0.90, 0.99], p = 0.014), 1 to 2 years (R = 0.80 [0.72, 0.88], p < 0.001) and 5 to 6 years (R = 0.71 [0.57, 0.87], p = 0.002). 2'FL was negatively associated with BMI consistently, reaching statistical significance at 3 months and 4 and 5 years. Children of non-secretors showed higher BMI at 3 months, 6 months, and 3, 6, and 7 years of age. CONCLUSION: We found that some associations between HMO and infant growth may extend beyond the infancy and breastfeeding periods. They highlight the importance of both maternal and infant parameters in the understanding of the underlying associations. TRIAL REGISTRATION: The study is registered with ClinicalTrial.gov: NCT02550236 .

Plasma and urinary inositol isomer profiles measured by UHPLC-MS/MS reveal differences in scyllo-inositol levels between non-pregnant and pregnant women.

Previous studies support that myo- and D-chiro-inositol isomers are promising bioactives for the treatment of women with polycystic ovary syndrome and for lowering the risk of gestational diabetes mellitus in pregnant women, whereas scyllo-inositol may have some benefits for neurological disorders (e.g., Alzheimer's disease). Though potentially useful to better understand inositol isomer metabolism and study their role in health and disease, routine analysis of inositol isomers in plasma and urine with a single analytical method is not yet feasible due to the lack of a suitable analytical assay. To address this, we developed and validated a robust ultra-high-performance-liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for the quantification of inositol isomers in plasma and urine. This method resolves seven inositol isomers with accurate quantification of total chiro- (D and L enantiomers), myo-, and scyllo-inositols and is semi-quantitative for neo-inositol. For urine and plasma myo-inositol, the method repeatability and intermediate reproducibility were below 6% and 8%, respectively. Then, for both chiro- and scyllo-inositols, repeatability and intermediate reproducibility were below 10% and 14%, respectively. A pilot study was carried out to quantify and compare the pattern of inositol isomers in urine and plasma of non-pregnant and pregnant women and showed for the first time that urinary myo- and scyllo-inositol concentrations were significantly higher for women in the third trimester of pregnancy compared with non-pregnant women. These findings warrant further research to understand the biological significance of the observed differences in inositol profiles and suggest a potential role of scyllo-inositol.Graphical abstract Plasma and urinary inositol isomer profiles measured by UHPLC-MS/MS reveal differences in scyllo-inositol levels between non-pregnant and pregnant women.

The Impact of Bed Traffic Control and Improved Flow Process on Throughput Measures in a Metropolitan Emergency Department.

INTRODUCTION: ED crowding is a complex phenomenon that presents many challenges to patients, hospitals, and staff. Using Lewin's change model, we implemented an ED improvement plan, including an innovative bed traffic control and improved flow system. We hypothesized that this plan would reduce door-to-provider time and emergency medical service-offloading time, decrease the length of stay and number of patients leaving without being seen by a physician, and increase overall patient satisfaction. METHODS: We examined the ED improvement plan's impact on institutional throughput metrics over a 4-year period (2015-2019). Data on door-to-provider time, door-to-discharge time, patient volume, leaving without being seen by a physician, and patient satisfaction by Press Ganey were analyzed. RESULTS: Between 2015 and 2018, the median door-to-provider time decreased 56.9% and the median door-to-discharge time decreased 29.6%. Percentage of patients who left without being seen by a physician decreased 73.8%. In 2018, the patient satisfaction rank increased by 16 points (84.2% increase). Emergency medical services-offloading time decreased significantly, prompting a change of the 30-minute cutoff to 20 minutes. In 2018, 0.84% of patients had an offloading time of more than 20 minutes. Preliminary 2019 data show maintenance of this trend for all hospital metrics. DISCUSSION: Implementing a pod system, with flow and bed placement managed by bed traffic control, reduced door-to-provider time, door-to-discharge time, leaving without being seen by a physician, emergency medical service-offload time, and increased patient satisfaction. Our results may provide a model for other emergency departments to effectively manage the challenges of crowding.

Determination of 2'-Fucosyllactose and Lacto-N-neotetraose in Infant Formula.

Human milk oligosaccharides (HMO) are the third most abundant solid component of human milk. It is likely that they are responsible for at least some of the benefits experienced by breast-fed infants. Until recently HMO were absent from infant formula, but 2'-fucosyllactose (2'-FL) and lacto-N-neoteraose (LNnT) have recently become available as ingredients. The development of formula containing these HMO and the quality control of such formula require suitable methods for the accurate determination of the HMO. We developed two different approaches for analysis of 2'-FL and LNnT in formula; high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and hydrophilic interaction liquid chromatography with fluorescence detection (HILIC-FLD). In lab trials using blank formula spiked with the two oligosaccharides, both approaches worked well with recoveries of 94⁻111% (HPAEC-PAD) and 94⁻104% (HILIC-FLD) and RSD (iR) of 2.1⁻7.9% (HPAEC-PAD) and 2.0⁻7.4% (HILIC-FLD). However, when applied to products produced in a pilot plant, the HPAEC-PAD approach sometimes delivered results below those expected from the addition rate of the ingredients. We hypothesize that the oligosaccharides interact with the formula matrix during the production process and, during sample preparation for HPAEC-PAD those interactions have not been broken. The conditions required for labeling the HMO for detection by the FLD apparently disrupt those interactions, and result in improved recoveries. It is likely that both analytical approaches are appropriate if a suitable extraction process is used to recover the HMO.

Determination of ß-Galactooligosaccharides (GOS) in Infant Formula: Collaborative Study, Final Action 2021.01.

BACKGROUND: We previously published a method for the determination of ß-Galactooligosaccharides (GOS) in Infant Formula and Adult Nutritionals which is currently First Action AOAC Method 2021.01. In this study, reproducibility data were collected to support the promotion of the method to Final Action. METHOD: A collaborative study was organized, to which 14 laboratories from eight different countries participated. Initially, laboratories were requested to analyze two practice samples and request guidance from the study director in case of issues. Successful laboratories proceeded to analyze seven samples (six infant formula and one adult nutritional) received as blind duplicates. RESULTS: Thirteen laboratories reported acceptable results for practice sample 1. Practice sample 2 could only be delivered to eight of the laboratories due to restrictions at customs. The 13 laboratories successfully analyzing practice sample 1 were requested to continue with the analysis of the MLT samples. Laboratory 14 was unable to solve some technical difficulties, so their data could not be used. Out of the seven samples tested, results for six infant formula met the requirements of the AOAC SMPR 2014.003, with RSDr ranging from 1.4 to 4.7% and RSDR ranging from 8.1 to 11.6%. The adult nutritional sample returned results outside the range of SPMR, having repeatability (RSDr) of 9.9%, higher than the SMPR target of ≤ 6%, and reproducibility (RSDR) of 12.1%, just above the SMPR target of ≤ 12%.

National patterns of vulnerable decision points in school discipline.

In this study, we identified the specific discipline decision situations (i.e., vulnerable decision points [VDPs]) that contribute most to racial discipline disparities from a sample of 2020 schools across the United States. We also examined how much VDPs contributed to overall discipline disparities and the extent to which there was similarity among the strongest VDPs within each school. Last, we directly compared the VDP that contributed most to disparities in each school to situations with the highest rates of office discipline referrals (ODRs) to identify the extent of agreement with overall school discipline patterns. We found the most common VDPs within schools to be subjective behaviors (e.g., defiance, disruption) in classrooms throughout the day, with ODRs for physical aggression contributing notably to disparities among the top 10 VDPs. The strongest single VDP accounted for an average of 17% of racial disparities across the school and the top three VDPs accounted for 37% of disparities. The strongest three VDPs within schools also were remarkably consistent across behavior and location. Finally, there was moderate agreement between situations with the most ODRs and those with the strongest racial disparities, with 63% of schools in the sample having VDPs identical to their situations with most ODRs. In the absence of prescriptive analysis of their own school data, the results of this study provide school leaders and intervention researchers with more precise, promising targets for intervention to increase educational equity.

Determination of Seven Human Milk Oligosaccharides (HMOs) in Infant Formula and Adult Nutritionals: First Action 2022.07.

BACKGROUND: Human milk oligosaccharides (HMOs) are important components of breast milk and may be responsible for some of the benefits of breastfeeding, including resistance to infections and the development of a healthy gut microbiota. Selected HMOs are now available for addition to infant formula, and suitable methods to control the dosing rate are needed. OBJECTIVE: To develop and validate a suitable method for the analysis of HMOs in infant formula. METHOD: A method was developed for the determination of seven human milk oligosaccharides (2'-fucosyllactose, 3-fucosyllactose, 3'-sialyllactose, 6'-sialyllactose (6'SL), 2',3-difucosyllactose, lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT)) in infant formula and adult nutritionals. The oligosaccharides are labeled at their reducing end with 2-aminobenzamide, separated by liquid chromatography and detected using a fluorescence detector. Maltodextrins are enzymatically hydrolyzed before analysis to prevent potential interference; likewise, an optional ß-galactosidase treatment can be used to remove ß-galactooligosaccharides. Fructooligosaccharides or polydextrose do not generally interfere with the analysis. RESULTS: The method has been validated in a single laboratory on infant formula and adult nutritionals. The seven HMOs were spiked into eight matrixes at three or four spike levels, giving a total of 176 data points. Recoveries were in the range of 90.9-109% in all cases except at the lowest spike level in one matrix (elemental formula), where the LNT recovery was 113%, the LNnT recovery was 111%, and the 6'SL recovery was 121%. Relative repeatabilities (RSD(r)) were in the range of 0.1-4.2%. The performance is generally within the requirements outlined in the Standard Method Performance Requirements (SMPR®) published by AOAC INTERNATIONAL. CONCLUSIONS: The method developed is suitable for the determination of seven HMOs in infant formula and demonstrated good performance during single-laboratory validation. HIGHLIGHTS: A method has been developed that is suitable for the determination of seven HMOs in infant formula.

Examining differential effects of an equity-focused schoolwide positive behavioral interventions and supports approach on teachers' equity in school discipline.

Following a randomized controlled trial that showed effectiveness of an equity-centered positive behavioral interventions and supports (PBIS) professional development intervention on student discipline in elementary schools, we studied the extent to which the intervention had differential effects on individual teachers' use of exclusionary discipline. Using the sample of teachers from the randomized controlled trial (n = 348), we assessed whether (a) changes in teacher use of office discipline referrals over the course of 2 school years and (b) intervention acceptability were moderated by teacher demographic characteristics (e.g., race/ethnicity, experience) or teacher attitudes (e.g., awareness of biases and commitment to equity). Results from multilevel models using two discipline outcomes (i.e., office discipline referrals issued to Black students and equity in office discipline referrals) did not show significant moderation effects for any demographic or attitude variables. Results of intervention acceptability found that teachers with pre-existing commitments to bias reduction found the intervention more acceptable, although means were consistently high across the sample. Findings indicate that the intervention was similarly effective on teacher discipline practices, regardless of teacher demographics or pre-existing attitudes, lending more support to the intervention's promise.

Capillary electrophoresis analysis of industrial galactooligosaccharides.

Galactooligosaccharides are added to infant formula to simulate some of the benefits associated with human milk oligosaccharides, in particular to modulate the gut microbiota. During our study the galactooligosaccharide content of an industrial GOS ingredient was determined by differential enzymatic digestion using amyloglucosidase and ß-galactosidase. The resulting digests were fluorophore labeled and analyzed by capillary gel electrophoresis with laser induced fluorescence detection. Quantification of the results were based on a lactose calibration curve. Utilizing this approach, the galactooligosaccharide concentration of the sample was determined as 37.23 g/100 g, very similar to earlier HPLC results, but requiring only 20 min separation time. The CGE-LIF method in conjunction with the differential enzymatic digestion protocol demonstrated in this paper offers a rapid and easy to use method to measure galactooligosaccharides and should be applicable to the determination of GOS in infant formulas and other products.

Human Milk Oligosaccharides, Important Milk Bioactives for Child Health: A Perspective.

Human milk contains all nutritive and bioactive compounds to give infants the best possible start in life. Human milk bioactives cover a broad range of components, including immune cells, antimicrobial proteins, microbes, and human milk oligosaccharides (HMOs). Over the last decade, HMOs have gained special attention as their industrial production has allowed the study of their structure-function relation in reductionist experimental setups. This has shed light on how HMOs steer microbiome and immune system development in early life but also how HMOs affect infant health (e.g., antibiotic use, respiratory tract infections). We are on the verge of a new era where we can examine human milk as a complex biological system. This allows not only study of the mode of action and causality of individual human milk components but also investigation of synergistic effects that might exist between different bioactives. This new wave in human milk research is largely fueled by significant advances in analytical tools in the field of systems biology and network analysis. It will be exciting to explore how human milk composition is affected by different factors, how different human milk compounds work together, and how this influences healthy infant development.

Human milk oligosaccharide composition and associations with growth: results from an observational study in the US.

Background: Breast milk is the recommended source of nutrients for newborns and infants. Human milk oligosaccharides (HMO) are the third most abundant solid component in human milk and their composition varies during lactation. Objectives: Our objective was to investigate longitudinal and cross-sectional changes in HMO composition and whether these changes were associated with infant growth up to 24 months of age. Associations with maternal characteristics were also investigated. Methods: 24 HMOs were quantified in samples taken at 2 weeks (n = 107), 6 weeks (n = 97) and 3 months (n = 76), using high performance liquid chromatography. Body length, weight, and head circumference were measured at 8 timepoints, until 24 months. Clusters of breast milk samples, reflecting different HMO profiles, were found through a data-driven approach. Longitudinal associations were investigated using functional principal component analysis (FPCA) and used to characterize patterns in the growth trajectories. Results: Four clusters of samples with similar HMO composition were derived. Two patterns of growth were identified for length, body weight and head circumference via the FPCA approach, explaining more than 90% of the variance. The first pattern measured general growth while the second corresponded to an initial reduced velocity followed by an increased velocity ("higher velocity"). Higher velocity for weight and height was significantly associated with negative Lewis status. Concentrations of 3'GL, 3FL, 6'GL, DSNLT, LNFP-II, LNFP-III, LNT, LSTb were negatively associated with higher velocity for length. Conclusion: We introduced novel statistical approaches to establish longitudinal associations between HMOs evolution and growth. Based on our approach we propose that HMOs may act synergistically on children growth. A possible causal relationship should be further tested in pre-clinical and clinical setting.

The Role of Human Milk Oligosaccharides in Myelination, Socio-Emotional and Language Development: Observational Data from Breast-Fed Infants in the United States of America.

Infancy is a critical period for neurodevelopment, which includes myelination, synaptogenesis, synaptic pruning, and the development of motor, social-emotional, and cognitive functions. Human milk provides essential nutrients to the infant's developing brain, especially during the first postnatal months. Human milk oligosaccharides (HMOs) are a major component of human milk, and there is growing evidence of the association of individual HMOs with cognitive development in early life. However, to our knowledge, no study has explained these associations with a mechanism of action. Here, we investigated possible mediating associations between HMOs in human milk, brain myelination (measured via myelin water fraction), and measures of motor, language (collected via the Bayley Scales of Infant and Toddler Development (Bayley-III)), and socioemotional development (collected via the Ages and Stages Questionnaire: Social-Emotional Version (ASQ-SE)) in healthy term-born breast-fed infants. The results revealed an association between 6'Sialyllactose and social skills that was mediated by myelination. Furthermore, associations of fucosylated HMOs with language outcomes were observed that were not mediated by myelination. These observations indicate the roles of specific HMOs in neurodevelopment and associated functional outcomes, such as social-emotional function and language development.

Determination of ß-Galactooligosaccharides (GOS) in Infant Formula and Adult Nutritionals: Single-Laboratory Validation, First Action 2021.01.

BACKGROUND: ß-Galactooligosaccharides (GOS) are typically used in infant formula and adult nutritionals as a source of nondigestible oligosaccharides, which may bring beneficial effects through modulation of the gut microbiota. However, suitable methods for the determination of GOS in products with a high background of lactose do not exist. OBJECTIVE: The aim of this work was to develop a method suitable for the determination of GOS in infant formula and adult nutritionals and demonstrate suitability through single laboratory validation. METHODS: Reducing oligosaccharides are labeled with 2-aminobenzamide (2AB), separated by hydrophilic interaction LC, and determined assuming that all oligosaccharides give an equimolar response in the detector. The same sample is analyzed a second time after treatment with ß-galactosidase to remove GOS. The difference in the determined oligosaccharides between the two measurements will be the GOS content of the sample. The method was validated in a single laboratory on infant formula and adult nutritionals. RESULTS: Recoveries were in the range 91.5-102%, relative standards of deviation (RSDr) were in the range 0.7-5.99%, and one sample had an RSDr of 8.30%. Except for the one sample with an RSDr of 8.30%, the performance is within the requirements outlined in the Standard Method Performance Requirements, which specifies recoveries in the range 90-110% and RSDr of below 6%. CONCLUSIONS: The method is suitable for the determination of GOS in infant formula and adult nutritionals. HIGHLIGHTS: A method has been developed which is suitable for the determination of GOS in products with a high background concentration of lactose (infant fromula and adult nutritionals). The method does not require access to the GOS ingredient used for the production of the finished product. It is also possible to separately quantify the amount of GOS containing three or more monomeric units in order to support dietary fibre analysis.

Human milk oligosaccharides in breast milk and 2-year outcome in preterm infants: An exploratory analysis.

BACKGROUND & AIMS: The health benefit of human milk (HM) for preterm infant development is known but the role of human milk oligosaccharides (HMOs) contained in HM remains underexplored. We explored the relationship between exposure to HMOs contained in mother's milk and growth and neurodevelopment at 2-years corrected age in preterm infants. METHODS: Exclusively breastfed preterm infants born between 27 and 34 weeks of gestation were enrolled in a monocentric prospective observational study, LACTACOL. Samples of breast milk were collected once a week for 7 weeks after birth. HMOs and sialic acid were measured by liquid chromatography. Age and Stages questionnaire (ASQ) version 2 was used to assess 2-year neurodevelopmental outcome. We analyzed the relationship between HMO content and (i) infant neurodevelopment at 2-years, and (ii) growth outcome at discharge and at 2 years. A secondary analysis was performed among Secretor(+) Lewis(+) mothers. Only associations with a false discovery rate of 10% or less according to the Benjamini-Hochberg procedure were considered significant. RESULTS: 137 preterm infants (mean gestational age of 31.3 ± 1.7 weeks, mean birth weight of 1494 g ± 336 g) born to 117 mothers (mean age of 30.8 ± 5.0 years) were enrolled. Total HMOs and most individual HMOs and sialic acid concentrations decreased with advancing postnatal age, except for lacto-N-fucopentaose-III and 3-fucosyllactose, which increased. Total HMOs were positively correlated with neonatal length growth (adjusted p = 0.012). Neither total HMOs nor any individual HMO correlated with ASQ score in the overall cohort. However, lacto-N-fucopentaose-III (LNFP-III) was significantly associated with total ASQ score (adjusted p ≤ 0.015) among the 104 infants born to Secretor(+) Lewis(+) mothers. CONCLUSIONS: In this exploratory study in very preterm infants, total HMOs and most individual HMOs, except LNFP-III, decreased with advancing postnatal age. Neither the concentration of total HMOs nor that of any individual HMO were associated with ASQ score at 2 years, except for LNFP-III in Secretor(+) Lewis(+) mothers.

On-line cleanup for 2-aminobenzamide-labeled oligosaccharides.

Analysis of 2-aminobenzamide-labeled oligosaccharides requires removal of excess labeling reagents before chromatography. Manual cleanup is time-consuming and not optimal for routine analysis, so an on-line solid-phase extraction was developed. Labeled oligosaccharides are trapped on an amide phase in a small guard column, the excess reagents are washed away, and then the sample is transferred to the analytical column for analysis. The on-line protocol shortened the sample preparation time and has been applied for the analysis of oligosaccharides and N-glycans released from glycoproteins.

Lactose does not interfere with the analysis of sialic acids as their 1,2-diamino-4,5-methylenedioxybenzene derivatives.

In 2007, Martin et al. developed a method for the analysis of sialic acids by HPLC following 1,2-diamino-4,5-methylenedioxybenzene (DMB) derivatisation (Martín et al., Anal Bioanal Chem 387:2943-2949, 2007). Within the article, the authors noted that lactose interfered with the analysis, giving erroneously high results when lactose-containing products were analysed. Such an observation is important when analysing milk-based products, yet was contradictory to the observations of Nakamura et al. (Chem Pharm Bull 35(2):687-692, 1987) who demonstrated that DMB was specific for α-keto acids and did not react with simple sugars such as glucose or lactose. In order to clarify the situation, this phenomenon was investigated and it was confirmed that lactose does not interfere with the analysis. However, it was found that most commercial preparations of lactose do contain small amounts of sialic acids, either as the free monosaccharide or bound to lactose in the form of 3'- and 6'-sialyllactose.

Biochemical and Morphological Characterization of Heterotrophic Crypthecodinium cohnii and Chlorella vulgaris Cell Walls.

Microalgae are attractive for the food and cosmetic industries because of their nutrient composition. However, the bioaccessibility and extractability of nutrients in microalgae are limited by the rigid and indigestible cell wall. The goal of this study is to explore the cell wall polysaccharides (CWPSs) composition and morphology in heterotrophic Crypthecodinium cohnii and Chlorella vulgaris biomasses during growth. Our results showed that glucose was the major component of CWPSs and exopolysaccharides in C. cohnii. C. vulgaris CWPSs have a similar sugar profile in exponential and stationary phases, essentially composed of rhamnose and galactose. C. vulgaris cell wall thickness increased from 82 nm in the exponential phase to 114 nm in the stationary phase and consisted of two main layers. C. cohnii's cell wall was 133 nm thick and composed of several membranes surrounding thecal plates. Understanding of the microalgae cell wall helps developing a more efficient and targeted biorefinery approach.