Zinc Supplementation Initiated Prior to or During Pregnancy Modestly Impacted Maternal Status and High Prevalence of Hypozincemia in Pregnancy and Lactation: The Women First Preconception Maternal Nutrition Trial.

BACKGROUND: Data regarding effects of small-quantity-lipid-based nutrient supplements (SQ-LNS) on maternal serum zinc concentrations (SZC) in pregnancy and lactation are limited. OBJECTIVES: The objectives of this study were to evaluate the effect of preconception compared with prenatal zinc supplementation (compared with control) on maternal SZC and hypozincemia during pregnancy and early lactation in women in low-resource settings, and assess associations with birth anthropometry. METHODS: From ∼100 women/arm at each of 3 sites (Guatemala, India, and Pakistan) of the Women First Preconception Maternal Nutrition trial, we compared SZC at 12- and 34-wk gestation (n = 651 and 838, respectively) and 3-mo postpartum (n = 742) in women randomly assigned to daily SQ-LNS containing 15 mg zinc from ≥3 mo before conception (preconception, arm 1), from ∼12 wk gestation through delivery (early pregnancy, arm 2) or not at all (control, arm 3). Birth anthropometry was examined for newborns with ultrasound-determined gestational age. Statistical analyses were performed separately for each time point. RESULTS: At 12-wk gestation and 3-mo postpartum, no statistical differences in mean SZC were observed among arms. At 34-wk, mean SZC for arms 1 and 2 were significantly higher than for arm 3 (50.3, 50.8, 47.8 µg/dL, respectively; P = 0.005). Results were not impacted by correction for inflammation or albumin concentrations. Prevalence of hypozincemia at 12-wk (<56 µg/dL) was 23% in Guatemala, 26% in India, and 65% in Pakistan; at 34 wk (<50 µg/dL), 36% in Guatemala, 48% in India, and 74% in Pakistan; and at 3-mo postpartum (<66 µg/dL) 79% in Guatemala, 91% in India, and 92% in Pakistan. Maternal hypozincemia at 34-wk was associated with lower birth length-for-age Z-scores (all sites P = 0.013, Pakistan P = 0.008) and weight-for-age Z-scores (all sites P = 0.017, Pakistan P = 0.022). CONCLUSIONS: Despite daily zinc supplementation for ≥7 mo, high rates of maternal hypozincemia were observed. The association of hypozincemia with impaired fetal growth suggests widespread zinc deficiency in these settings. This trial is registered at clinicaltrials.gov as #NCT01883193.

Anthropometric and sociodemographic variables, but not preconception or prenatal maternal nutrition supplementation, predict neurodevelopment in offspring of the 'Women First' trial.

Multiple factors influence infant and child neurodevelopment in low resource settings. In offspring of participants in the preconception maternal nutrition trial, Women First (WF), we examined the impact of providing a preconception (Arm 1) or prenatal (Arm 2) nutrient supplement (compared to controls, Arm 3) on neurodevelopmental outcomes at 24 months; predictors of neurodevelopment scores; and associations of infant anthropometrics with neurodevelopmental scores. Follow-up visits for anthropometry were conducted at 6-, 12-, 18- and 24-month of age. At 24-months, in a randomized subset, the Bayley Scales of Infant Development, 3rd edition (BSID-III), including cognitive, motor and social-emotional subscales, and the Family Care Indicators (FCI) questionnaire, assessing family and home environment, were completed. Multiple covariates (intervention arm, site, maternal sociodemographic characteristics, FCI subscales, birthweight and 6-24 months' change in anthropometry z-scores, (e.g., ΔLAZ6-2 4) were evaluated by linear regression to predict BSID-III outcomes and to assess associations of anthropometric changes with BSID-III scores. The analysis consisted of 1386 infants (n = 441, 486, 459 for Arms 1, 2 and 3, respectively). None of the domain-specific BSID-III subscale scores differed by maternal intervention arm. Four covariates significantly predicted (p ≤ 0.01) all 3 BSID-III subscales: secondary maternal education, ΔLAZ6 - 24, birthweight >2500 g, and FCI play materials. Linear growth was associated with all domains of neurodevelopment. The results underscore the multi-dimensional aspects of child development represented by the nurturing care framework, including prenatal maternal nutrition, post-natal growth, maternal education for responsive caregiving and opportunities for early learning.

Machine Learning-Based Fragment Selection Improves the Performance of Qualitative PRM Assays.

Targeted mass spectrometry-based platforms have become a valuable tool for the sensitive and specific detection of protein biomarkers in clinical and research settings. Traditionally, developing a targeted assay for peptide quantification has involved manually preselecting several fragment ions and establishing a limit of detection (LOD) and a lower limit of quantitation (LLOQ) for confident detection of the target. Established thresholds such as LOD and LLOQ, however, inherently sacrifice sensitivity to afford specificity. Here, we demonstrate that machine learning can be applied to qualitative PRM assays to discriminate positive from negative samples more effectively than a traditional approach utilizing conventional methods. To demonstrate the utility of this method, we trained an ensemble machine learning model using 282 SARS-CoV-2 positive and 994 SARS-CoV-2 negative nasopharyngeal swabs (NP swab) analyzed using a targeted PRM method. This model was then validated using an independent set of 200 positive and 150 negative samples and achieved a sensitivity of 92% relative to results obtained by RT-PCR, which was superior to a traditional approach that resulted in 86.5% sensitivity when analyzing the same data. These results demonstrate that machine learning can be applied to qualitative PRM assays and results in superior performance relative to traditional methods.

Targeted Detection of SARS-CoV-2 Nucleocapsid Sequence Variants by Mass Spectrometric Analysis of Tryptic Peptides.

COVID-19 vaccines are becoming more widely available, but accurate and rapid testing remains a crucial tool for slowing the spread of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus. Although the quantitative reverse transcription-polymerase chain reaction (qRT-PCR) remains the most prevalent testing methodology, numerous tests have been developed that are predicated on detection of the SARS-CoV-2 nucleocapsid protein, including liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay-based approaches. The continuing emergence of SARS-CoV-2 variants has complicated these approaches, as both qRT-PCR and antigen detection methods can be prone to missing viral variants. In this study, we describe several COVID-19 cases where we were unable to detect the expected peptide targets from clinical nasopharyngeal swabs. Whole genome sequencing revealed that single nucleotide polymorphisms in the gene encoding the viral nucleocapsid protein led to sequence variants that were not monitored in the targeted assay. Minor modifications to the LC-MS/MS method ensured detection of the variants of the target peptide. Additional nucleocapsid variants could be detected by performing the bottom-up proteomic analysis of whole viral genome-sequenced samples. This study demonstrates the importance of considering variants of SARS-CoV-2 in the assay design and highlights the flexibility of mass spectrometry-based approaches to detect variants as they evolve.

Isotopic Distribution Calibration for Mass Spectrometry.

Mass spectrometry (MS) is widely used in science and industry. It allows accurate, specific, sensitive, and reproducible detection and quantification of a huge range of analytes. Across MS applications, quantification by MS has grown most dramatically, with >50 million experiments/year in the USA alone. However, quantification performance varies between instruments, compounds, different samples, and within- and across runs, necessitating normalization with analyte-similar internal standards (IS) and use of IS-corrected multipoint external calibration curves for each analyte, a complicated and resource-intensive approach, which is particularly ill-suited for multi-analyte measurements. We have developed an internal calibration method that utilizes the natural isotope distribution of an IS for a given analyte to provide internal multipoint calibration. Multiple isotope distribution calibrators for different targets in the same sample facilitate multiplex quantification, while the emerging random-access automated MS platforms should also greatly benefit from this approach. Finally, isotope distribution calibration allows mathematical correction for suboptimal experimental conditions. This might also enable quantification of hitherto difficult, or impossible to quantify, targets, if the distribution is adjusted in silico to mimic the analyte. The approach works well for high resolution, accurate mass MS for analytes with at least a modest-sized isotopic envelope. As shown herein, the approach can also be applied to lower molecular weight analytes, but the reduction in calibration points does reduce quantification performance.

Analytical Sensitivity and Specificity of Four Point of Care Rapid Antigen Diagnostic Tests for SARS-CoV-2 Using Real-Time Quantitative PCR, Quantitative Droplet Digital PCR, and a Mass Spectrometric Antigen Assay as Comparator Methods.

BACKGROUND: We evaluated the analytical sensitivity and specificity of 4 rapid antigen diagnostic tests (Ag RDTs) for severe acute respiratory syndrome coronavirus 2, using reverse transcription quantitative PCR (RT-qPCR) as the reference method and further characterizing samples using droplet digital quantitative PCR (ddPCR) and a mass spectrometric antigen test. METHODS: Three hundred fifty (150 negative and 200 RT-qPCR positive) residual PBS samples were tested for antigen using the BD Veritor lateral flow (LF), ACON LF, ACON fluorescence immunoassay (FIA), and LumiraDx FIA. ddPCR was performed on RT-qPCR-positive samples to quantitate the viral load in copies/mL applied to each Ag RDT. Mass spectrometric antigen testing was performed on PBS samples to obtain a set of RT-qPCR-positive, antigen-positive samples for further analysis. RESULTS: All Ag RDTs had nearly 100% specificity compared to RT-qPCR. Overall analytical sensitivity varied from 66.5% to 88.3%. All methods detected antigen in samples with viral load >1 500 000 copies/mL RNA, and detected ≥75% of samples with viral load of 500 000 to 1 500 000 copies/mL. The BD Veritor LF detected only 25% of samples with viral load between 50 000 to 500 000 copies/mL, compared to 75% for the ACON LF device and >80% for LumiraDx and ACON FIA. The ACON FIA detected significantly more samples with viral load <50 000 copies/mL compared to the BD Veritor. Among samples with detectable antigen and viral load <50 000 copies/mL, sensitivity of the Ag RDT varied between 13.0% (BD Veritor) and 78.3% (ACON FIA). CONCLUSIONS: Ag RDTs differ significantly in analytical sensitivity, particularly at viral load <500 000 copies/mL.

A SISCAPA-based approach for detection of SARS-CoV-2 viral antigens from clinical samples.

SARS-CoV-2, a novel human coronavirus, has created a global disease burden infecting > 100 million humans in just over a year. RT-PCR is currently the predominant method of diagnosing this viral infection although a variety of tests to detect viral antigens have also been developed. In this study, we adopted a SISCAPA-based enrichment approach using anti-peptide antibodies generated against peptides from the nucleocapsid protein of SARS-CoV-2. We developed a targeted workflow in which nasopharyngeal swab samples were digested followed by enrichment of viral peptides using the anti-peptide antibodies and targeted parallel reaction monitoring (PRM) analysis using a high-resolution mass spectrometer. This workflow was applied to 41 RT-PCR-confirmed clinical SARS-CoV-2 positive nasopharyngeal swab samples and 30 negative samples. The workflow employed was highly specific as none of the target peptides were detected in negative samples. Further, the detected peptides showed a positive correlation with the viral loads as measured by RT-PCR Ct values. The SISCAPA-based platform described in the current study can serve as an alternative method for SARS-CoV-2 viral detection and can also be applied for detecting other microbial pathogens directly from clinical samples.

Preconceptional Lipid-Based Nutrient Supplementation in 2 Low-Resource Countries Results in Distinctly Different IGF-1/mTOR Placental Responses.

BACKGROUND: Preconceptional maternal small-quantity lipid-based nutrient supplementation (SQLNS) improved intrauterine linear growth in low-resource countries as demonstrated by the Women First Preconception Maternal Nutrition Trial (WF). Fetal growth is dependent on nutrient availability and regulated by insulin-like growth factor 1 (IGF-1) through changes in placental transfer capacity, mediated by the mechanistic target of rapamycin (mTOR) pathway. OBJECTIVES: Our objective was to evaluate the role of placental mTOR and IGF-1 signaling on fetal growth in women from 2 low-resource countries with high rates of stunting after they received preconceptional SQLNS. METHODS: We studied 48 women from preconception through delivery who were from Guatemala and Pakistan and received SQLNS or not, as part of the WF study. Placental samples were obtained at delivery (control, n = 24; SQLNS, n = 24). Placental protein or mRNA expression of eukaryotic translation initiation factor binding protein-1 (4E-BP1), ribosomal protein S6 (rpS6), AMP-activated protein kinase α (AMPKA), IGF-1, insulin-like growth factor receptor (IGF-1R), and pregnancy associated plasma protein (PAPP)-A, and DNA methylation of the IGF1 promoter were determined. Maternal serum IGF-1, insulin-like growth factor binding protein (IGFBP)-3, IGFBP-4, IGFBP-5, PAPP-A, PAPP-A2, and zinc were measured. RESULTS: Mean ± SEM maternal prepregnancy BMI differed between participants in Guatemala (26.5 ± 1.3) and Pakistan (19.8 ± 0.7) (P < 0.001). In Pakistani participants, SQLNS increased the placental rpS6(T37/46):rpS6 ratio (1.5-fold) and decreased the AMPKA(T172):AMPKA ratio. Placental IGF1 mRNA expression was positively correlated with birth length and birth weight z-scores. Placental PAPP-A (30-fold) and maternal serum zinc (1.2-fold) increased with SQLNS. In Guatemalan participants SQLNS did not influence placental mTOR signaling. Placental IGF-1R protein expression was positively associated with birth length and birth weight z-scores. SQLNS increased placental PAPP-A (40-fold) and maternal serum IGFBP-4 (1.6-fold). CONCLUSIONS: In Pakistani pregnant women with poor nutritional status, preconceptional SQLNS activated placental mTOR and IGF-1 signaling and was associated with improved fetal growth. In contrast, in Guatemalan women SQLNS did not activate placental nutrient-sensing pathways. In populations experiencing childhood stunting, preconceptional SQLNS improves placental function and fetal growth only in the context of poor maternal nutrition. This trial was registered at clinicaltrials.gov as NCT01883193.

Development of a pregnancy-specific reference material for thyroid biomarkers, vitamin D, and nutritional trace elements in serum.

OBJECTIVES: Matrix differences among serum samples from non-pregnant and pregnant patients could bias measurements. Standard Reference Material 1949, Frozen Human Prenatal Serum, was developed to provide a quality assurance material for the measurement of hormones and nutritional elements throughout pregnancy. METHODS: Serum from non-pregnant women and women in each trimester were bottled into four levels based on pregnancy status and trimester. Liquid chromatography tandem mass spectrometry (LC-MS/MS) methods were developed and applied to the measurement of thyroid hormones, vitamin D metabolites, and vitamin D-binding protein (VDBP). Copper, selenium, and zinc measurements were conducted by inductively coupled plasma dynamic reaction cell MS. Thyroid stimulating hormone (TSH), thyroglobulin (Tg), and thyroglobulin antibody concentrations were analyzed using immunoassays and LC-MS/MS (Tg only). RESULTS: Certified values for thyroxine and triiodothyronine, reference values for vitamin D metabolites, VDBP, selenium, copper, and zinc, and information values for reverse triiodothyronine, TSH, Tg, and Tg antibodies were assigned. Significant differences in serum concentrations were evident for all analytes across the four levels (p≤0.003). TSH measurements were significantly different (p<0.0001) among research-only immunoassays. Tg concentrations were elevated in research-only immunoassays vs. Federal Drug Administration-approved automated immunoassay and LC-MS/MS. Presence of Tg antibodies increased differences between automated immunoassay and LC-MS/MS. CONCLUSIONS: The analyte concentrations' changes consistent with the literature and the demonstration of matrix interferences in immunoassay Tg measurements indicate the functionality of this material by providing a relevant matrix-matched reference material for the different stages of pregnancy.

Improved first trimester maternal iodine status with preconception supplementation: The Women First Trial.

Maternal iodine (I) status is critical in embryonic and foetal development. We examined the effect of preconception iodine supplementation on maternal iodine status and on birth outcomes. Non-pregnant women in Guatemala, India and Pakistan (n ~ 100 per arm per site) were randomized ≥ 3 months prior to conception to one of three intervention arms: a multimicronutrient-fortified lipid-based nutrient supplement containing 250-µg I per day started immediately after randomization (Arm 1), the same supplement started at ~12 weeks gestation (Arm 2) and no intervention supplement (Arm 3). Urinary I (µg/L) to creatinine (mg/dl) ratios (I/Cr) were determined at 12 weeks for Arm 1 versus Arm 2 (before supplement started) and 34 weeks for all arms. Generalized linear models were used to assess the relationship of I/Cr with arm and with newborn anthropometry. At 12 weeks gestation, adjusted mean I/Cr (µg/g) for all sites combined was significantly higher for Arm 1 versus Arm 2: (203 [95% CI: 189, 217] vs. 163 [95% CI: 152, 175], p < 0.0001). Overall adjusted prevalence of I/Cr < 150 µg/g was also lower in Arm 1 versus Arm 2: 32% (95% CI: 26%, 38%) versus 43% (95% CI: 37%, 49%) (p = 0.0052). At 34 weeks, adjusted mean I/Cr for Arm 1 (235, 95% CI: 220, 252) and Arm 2 (254, 95% CI: 238, 272) did not differ significantly but were significantly higher than Arm 3 (200, 95% CI: 184, 218) (p < 0.0001). Nominally significant positive associations were observed between I/Cr at 12 weeks and birth length and head circumference z-scores (p = 0.028 and p = 0.005, respectively). These findings support the importance of first trimester iodine status and suggest need for preconception supplementation beyond salt iodization alone.

Center of Mass Calculation in Combination with MS/MS Allows Robust Identification of Single Amino Acid Polymorphisms in Clinical Measurements of Insulin-Like Growth Factor-1.

Insulin-like growth factor-1 (IGF-1) measurement by high-resolution accurate mass-mass spectrometry (HRAM-MS) is replacing IGF-1 immunoassays and allows for identification of single amino acid variants; by contrast, both normal and deleterious sequence variants might be missed by immunoassays or non-HRAM-MS methods. We have developed an intact molecule HRAM-MS method to identify IGF-1 variants, distinguishing them by a center of mass (COM) calculation, followed by various tandem-MS activation techniques (HCD, ETD, ETciD, EThcD, UVPD). We found single amino acid variants in 841 of 146 620 patient samples (0.57%). Most were benign (A67T, A70T). We also observed a pathogenic variant (V44M), likely pathogenic variants (A38V, V17M), and a likely benign variant (A67V). For 207 samples from unique patients with residual serum, the MS variant results were confirmed by cell-free DNA sequencing. Our approach allows accurate quantitative reporting of functional IGF-1 in the presence of single amino acid variants. The COM approach potentially enables omission of tandem-MS for known, common variants, while the combination of COM and tandem-MS allows accurate identification in all cases we encountered. This approach should be applicable to qualitative and quantitative analyses of other peptides/proteins in clinical and research settings and might lend itself to the characterization of other protein variations.

Immediate Interpretation and Results Communication Decreases Patient Anxiety: Experience in a Private Practice Community Hospital.

OBJECTIVE. The study objectives were to evaluate the percentage of patients interested in immediate radiologic results and to measure patient anxiety and hospital loyalty with this program in a private practice community hospital setting. SUBJECTS AND METHODS. Between December 2018 and May 2019, 100 patients 18-89 years old with a primary diagnosis of abdominal pain had imaging orders for CT, ultrasound, or nuclear medicine-hepatobiliary iminodiacetic acid scans and subsequently were asked if they wanted immediate results. Those who opted for immediate results were given a two-question survey before and after results delivery that asked about their anxiety level and imaging center loyalty. Data were entered using SurveyMonkey (SVMK) and analyzed using SAS software (version 9.4, SAS Institute). RESULTS. The majority (78%) of patients wanted immediate results. There were statistically significant differences in anxiety level before and after results delivery; 37% (p < 0.001) reported decreased anxiety after receiving imaging results, whereas 57% reported no change in anxiety (p < 0.001). The decision whether to come back to this imaging center (hospital loyalty) did not change before and after test results; 85% of participants strongly agreed that they would return. CONCLUSION. It is feasible for private practice radiologists to discuss CT, ultrasound, or nuclear medicine imaging results with patients in a community hospital setting. The majority of patients preferred immediate results over traditional methods of notification. Most patients reported anxiety about their imaging results, and a statistically significant number had decreased anxiety after discussing results with radiologists.

Radiologists Include Contact Telephone Number in Reports: Experience With Patient Interaction.

OBJECTIVE. The purpose of this study is to evaluate the experience of radiologists who include contact information in radiology reports in an era of open access to reports via patient portals. SUBJECTS AND METHODS. A prospective nonrandomized survey of all 61 radiologists in a single private practice group was conducted between July and August 2019. The survey, which consisted of 21 questions, was administered via a secure online survey software platform and distributed by e-mail. Participation was voluntary and anonymous. Data were analyzed using statistical analysis software. RESULTS. A total of 87% (53 of 61) of the radiologists completed the survey. Of these radiologists, 78% (41 of 52) indicated that they include their telephone number in radiology reports 75% or more of the time, with one radiologist not providing a response. Thirty-six percent of the radiologists are contacted once a year by patients, and 27% are contacted once a month. Of the 41 radiologists who include contact information 75% of the time or more, most (56% [23 of 41]) reported an increase in the frequency of patient contact. The reasons why radiologists had a patient contact them were to better understand the radiology report (95% of radiologists), to seek follow-up recommendations (39%), to express gratitude (34%), and to point out mistakes in the report (27%). Moreover, 98% (40 of 41) of radiologists reported never receiving complaints from a referring physician. Only 2% of radiologists stated that patient interaction was detrimental to workflow. Most radiologists found that interacting with patients was a satisfying experience and indicated that they would welcome more patient interaction. CONCLUSION. Including radiologist contact information in radiology reports increases patient-radiologist interaction. Despite this increased patient interaction, most radiologists indicated that they would welcome more interaction and found the communication satisfying.

Patient-centered Radiology: Where Are We, Where Do We Want to Be, and How Do We Get There?

Purpose The objectives of the Radiological Society of North America (RSNA) Patient-Centered Radiology Steering Committee survey were to (a) assess RSNA members' general attitudes and experiences concerning patient-centered radiology, with specific attention paid to radiologist-to-patient communication; (b) examine the members' barriers to communicating more directly with patients; and (c) explore their perceptions of how such barriers can be overcome. Materials and Methods A total of 5999 radiologists were invited by e-mail to complete an anonymous electronic survey developed by the Steering Committee and the RSNA Department of Research. Participants were asked to identify aspects of patient-centered care important to their practice, report on their interactions with patients, and share their opinions on radiologist-patient communication. Statistical analyses were performed by using the χ2 test and analysis of variance. Results The response rate was 12% (n = 694, 109 invitations were undeliverable). Most respondents (89%, 611 of 684) agreed that promoting awareness of the role of radiology in patients' overall health care is important to how they practice. The majority (73%, 421 of 575) reported that time or workload frequently prevented them from communicating directly with patients. The majority (74%, 423 of 572) reported that a personal sense of satisfaction was likely to motivate them to communicate more directly with patients, but many commented that changes to reimbursement and compensation would help them communicate with patients more directly. Conclusion Many radiologists support the concept of communicating more directly with patients but report they are constrained by time or workload. Changes to reimbursement schemes may help mitigate these barriers to one crucial aspect of patient-centered care. © RSNA, 2017 Online supplemental material is available for this article.

Upregulation of Zinc Absorption Matches Increases in Physiologic Requirements for Zinc in Women Consuming High- or Moderate-Phytate Diets during Late Pregnancy and Early Lactation.

Background: Estimated physiologic requirements (PRs) for zinc increase in late pregnancy and early lactation, but the effect on dietary zinc requirements is uncertain.Objective: The aim of this study was to determine changes in daily fractional absorbed zinc and total absorbed zinc (TAZ) from ad libitum diets of differing phytate contents in relation to physiologic zinc requirements during pregnancy and lactation.Methods: This was a prospective observational study of zinc absorption at 8 (phase 1) and 34 (phase 2) wk of gestation and 2 (phase 3) and 6 (phase 4) mo of lactation. Participants were indigenous Guatemalan women of childbearing age whose major food staple was maize and who had been randomly assigned in a larger study to either of 2 ad libitum feeding groups: low-phytate maize (LP; 1.6 mg/g; n = 14) or control maize (C; 7.1 mg/g; n = 8). Total dietary zinc (milligrams per day, TDZ) and phytate (milligrams per day) were determined from duplicate diets and fractional absorption (FAZ) by dual isotope ratio technique (TAZ = TDZ × FAZ). All variables were examined longitudinally and by group and compared with PRs. TAZ values at later phases were compared with phase 1. Measured TAZ was compared with predicted TAZ for nonpregnant, nonlactating (NPNL) women.Results: TAZ was greater in the LP group than in the C group at all phases. All variables increased from phase 1 to phases 2 and 3 and declined at phase 4. TAZ increased by 1.25 mg/d (P = 0.045) in the C group and by 0.81 mg/d (P = 0.058) in the LP group at phase 2. At phase 3, the increases were 2.66 mg/d (P = 0.002) in the C group and 2.28 mg/d (P = 0.0004) in the LP group, compared with a 1.37-mg/d increase in PR. Measured TAZ was greater than predicted values in phases 2-4.Conclusions: Upregulation of zinc absorption in late pregnancy and early lactation matches increases in PRs of pregnant and lactating women, regardless of dietary phytate, which has implications for dietary zinc requirements of pregnant and lactating women.

The structural basis of urea-induced protein unfolding in ß-catenin.

Although urea and guanidine hydrochloride are commonly used to denature proteins, the molecular underpinnings of this process have remained unclear for a century. To address this question, crystal structures of ß-catenin were determined at various urea concentrations. These structures contained at least 105 unique positions that were occupied by urea molecules, each of which interacted with the protein primarily via hydrogen bonds. Hydrogen-bond competition experiments showed that the denaturing effects of urea were neutralized when polyethylene glycol was added to the solution. These data suggest that urea primarily causes proteins to unfold by competing and disrupting hydrogen bonds in proteins. Moreover, circular-dichroism spectra and nuclear magnetic resonance (NMR) analysis revealed that a similar mechanism caused protein denaturation in the absence of urea at pH levels greater than 12. Taken together, the results led to the conclusion that the disruption of hydrogen bonds is a general mechanism of unfolding induced by urea, high pH and potentially other denaturing agents such as guanidine hydrochloride. Traditionally, the disruption of hydrophobic interactions instead of hydrogen bonds has been thought to be the most important cause of protein denaturation.

Alpha-1-Antitrypsin (A1AT) Proteotyping by LC-MS/MS.

The diagnosis of alpha-1-antitrypsin (A1AT) deficiency is established by quantitation of protein concentration in serum (immunoassay) followed by determination of specific allelic variants by phenotyping (isoelectric focusing (IEF) gel electrophoresis) and/or allele-specific genotyping. Various phenotyping and genotyping methodologies are available, and each has their own advantages and disadvantages. As an alternative, mass spectrometry is emerging as a powerful tool in the identification and quantitation of proteins and peptides. The method described here, referred to as proteotyping, is a proteomic method using trypsin digestion and tandem mass spectrometry that detects the most common deficiency alleles, S and Z, associated with A1AT deficiency.This qualitative mass spectrometry method is based on the principle that the S and Z mutations lead to amino acid changes which result in a change in the mass of the A1AT protein. When the A1AT protein is proteolytically digested, multiple peptides are generated, two of which include the sites of the S and Z mutations, respectively. Peptides generated from wild-type A1AT (M alleles) differ in sequence and mass from peptides generated from the S and Z alleles at these two specific locations. The mass difference allows for differentiation of S and Z peptides, representing the deficiency alleles, from non-S and non-Z peptides, representing the wild-type alleles (M). Interpretation of the peptide patterns in conjunction with A1AT quantitation by immunoassay allows for an accurate assessment for the presence of deficiency alleles in the majority of patients.

Using differential mobility spectrometry to improve the specificity of targeted measurements of 2,3-dinor 11ß-Prostaglandin F2α.

INTRODUCTION: 2,3-dinor 11ß-Prostaglandin F2α (BPG) is an arachidonic acid derivative and the most abundant metabolic byproduct of prostaglandin D2, which is released during mast cell activation. Therefore, measurements of BPG in urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) provide a noninvasive method for evaluation and management of mast cell disorders. Measurements obtained by LC-MS/MS exhibit a high prevalence of chromatographic interferences resulting in challenges with optimal determination of BGP. In this investigation, differential mobility spectrometry (DMS) is utilized to overcome the limitations of current testing. METHODS: Urine samples were extracted using an automated solid-phase extraction method. Samples were then analyzed with and without DMS devices installed on two commercially available mass spectrometry platforms to assess the benefits of DMS. Following promising results from a preliminary analytical evaluation, LC-DMS-MS/MS measurements of BPG in urine were fully validated to assess the analytical implications of using this technology. RESULTS AND DISCUSSION: The addition of DMS devices to the LC-MS/MS systems evaluated in this investigation significantly reduced interferences observed in the chromatograms. Concomitantly, DMS reduced the number of discordant quantifier/qualifier fragment ion results that significantly exceeded the ± 20 % limits, suggesting greater analytical specificity. The validation studies yielded low interday imprecision, with %CVs less than 6.5 % across 20 replicate measurements. Validation studies assessing other aspects of analytical performance also met acceptance criteria. CONCLUSIONS: Incorporating DMS devices greatly improved the specificity of BPG measurements by LC-MS/MS, as evidenced by the comparison of chromatograms and fragment ion results. Validation studies showed exceptional performance for established analytical metrics, indicating that this technology can be used to minimize the impact of interferences without adversely impacting other aspects of analytical or clinical performance.

Macrostructural Brain Morphology as Moderator of the Relationship Between Pandemic-Related Stress and Internalizing Symptomology During COVID-19 in High-Risk Adolescents.

BACKGROUND: According to person-by-environment models, individual differences in traits may moderate the association between stressors and the development of psychopathology; however, findings in the literature have been inconsistent and little literature has examined adolescent brain structure as a moderator of the effects of stress on adolescent internalizing symptoms. The COVID-19 pandemic presented a unique opportunity to examine the associations between stress, brain structure, and psychopathology. Given links of cortical morphology with adolescent depression and anxiety, the present study investigated whether cortical morphology moderates the relationship between stress from the COVID-19 pandemic on the development of internalizing symptoms in familial high-risk adolescents. METHODS: Prior to the COVID-19 pandemic, 72 adolescents (27M) completed a measure of depressive and anxiety symptoms and underwent magnetic resonance imaging. T1-weighted images were acquired to assess cortical thickness and surface area. Approximately 6-8 months after COVID-19 was declared a global pandemic, adolescents reported their depressive and anxiety symptoms and pandemic-related stress. RESULTS: Adjusting for pre-pandemic depressive and anxiety symptoms and stress, increased pandemic-related stress was associated with increased depressive but not anxiety symptoms. This relationship was moderated by cortical thickness and surface area in the anterior cingulate and cortical thickness in the medial orbitofrontal cortex such that increased stress was only associated with increased depressive and anxiety symptoms among adolescents with lower cortical surface area and higher cortical thickness in these regions. CONCLUSIONS: Results further our understanding of neural vulnerabilities to the associations between stress and internalizing symptoms in general, and during the COVID-19 pandemic in particular.