Molecular Mechanism of Starch Digestion by Family 31 Glycoside Hydrolases: Structural Characterization and Inhibition Studies of C-terminal Maltase Glycoamylase and Sucrase Isomaltase

Although carbohydrates are a principal component of the human diet, the mechanism of the final stages of starch digestion is not fully understood. One approach to treating metabolic diseases such as type II diabetes, obesity, and congenital sucrase isomaltase deficiency is inhibition of intestinal α-glucosidases and pancreatic α-amylases. Intestinal α-glucosidases, sucrase isomaltase (SI) and maltase glucoamylase (MGAM), are responsible for the final step of starch hydrolysis in mammals: the release of free glucose. MGAM and SI consist of two catalytic subunits: N-terminal and C-terminal, with overlapping, but variant substrate specificities. The objective of this thesis is to increase the understanding of the differential substrate specificity seen in the catalytic subunits of SI and MGAM. Through inhibitor studies, the structural and biochemical differences between the enzymatic subunits are explored, illustrating that each individual catalytic subunit can be selectively inhibited. In Chapter 3, homology models of ctSI and ctMGAM-N20 are presented, giving insight into the residues hypothesized to impact substrate specificity, enhancing our understanding of the functionality of these enzymatic subunits and overlapping substrate specificity. The structural implications of mutations seen in ntSI in CSID patients and the potential functional and structural implications are discussed in Chapter 4 in addition to the prevalence of SNPs in the SI gene in different populations. The mammalian α-glucosidases are compared to the 3 Å structure of CfXyl31, a Family 31 glycoside hydrolase from Cellulomonas fimi. Comparison to Family 31 glycoside hydrolases of known structure gives rise to possible mutations proposed to mimic ntMGAM α-glucosidase activity. Through inhibitor studies, homology models, examining mutations found in disease states such as congenital sucrase isomaltase deficiency, and investigating a bacterial family 31 glycoside hydrolase from Cellulomonas fimi, the active site characteristics and substrate specificities of SI and MGAM are better understood

Before You Tie the Knot: Mapping Pedagogy, Learning Outcomes, and Effect Size in Premarital Education

Human services educators are continually seeking ways to make instruction more effective and engaging. This study evaluated the AIAI-FTFD (Attention, Interact, Apply, Invite – Fact, Think, Feel, Do) Start-to-Finish Teaching Model for educators in an ongoing premarital educational program to determine the model’s effectiveness in implementing the concept of “teaching as an intervention” in human services educational programming. The AIAI-FTFD Model is designed to first, assist instructors to engage the audience’s attention, then introduce the information being taught with the purpose to facilitate interaction between the instructor and participants, next elicit application of the material to personal contexts, and finally, offer an invitation to participants to commit to practice the skills learned. This implementation science study assessed the targeted cognitive, emotional, and behavioral learning outcomes generated by using the AIAI-FTFD Model while completing the Before You Tie the Knot (BYTK) premarital education program online. A self-reported quantitative evaluation design was utilized to assess key objectives in the sample (n = 97). Clearly evident effect sizes were found in perceived knowledge and confidence gain in the ability to implement the skills covered in the training. Implications for how the AIAI-FTFD Model can facilitate change and learning in educational settings are discussed

Prenatal pet keeping and caregiver-reported attention deficit hyperactivity disorder through preadolescence in a United States birth cohort

BACKGROUND: While the keeping of pets has been shown to protect against childhood allergic disease and obesity, less is known regarding potential associations of prenatal pet keeping and attention deficit hyperactivity disorder (ADHD). We sought to examine the associations between prenatal dog or cat keeping with caregiver-reported ADHD in preadolescents in the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study (WHEALS) birth cohort (N = 1258). METHODS: At an interview with the caregiver at child age 10-12 years, caregivers reported if the WHEALS child had ever been diagnosed with ADHD. Similarly, during an interview with the mother prenatally, pet keeping (defined as dog or cat kept inside ≥1 h/day) was ascertained. Logistic regression models were fit to examine the association of prenatal pet keeping (dog keeping and cat keeping, separately) with ADHD. RESULTS: A subset of 627 children were included in the analyses: 93 who had ADHD and 534 with neurotypical development. After accounting for confounders and loss to follow-up, maternal prenatal dog exposure was associated with 2.23 times (95% CI: 1.15, 4.31; p = 0.017) greater odds of ADHD among boys. Prenatal dog keeping was not statistically significantly associated with ADHD in girls (odds ratio = 0.27, 95% CI: 0.06, 1.12; p = 0.070). Prenatal cat keeping was not associated with ADHD. CONCLUSIONS: In boys, but not girls, maternal prenatal dog keeping was positively associated with ADHD. Further study to confirm these findings and to identify potential mechanisms of this association (e.g., modification of the gut microbiome, exposure to environmental toxicants or pet-related medications) is needed

The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application

Background: A novel human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was identified in China in December 2019. There is limited support for many of its key epidemiologic features, including the incubation period for clinical disease (coronavirus disease 2019 [COVID-19]), which has important implications for surveillance and control activities. Objective: To estimate the length of the incubation period of COVID-19 and describe its public health implications. Design: Pooled analysis of confirmed COVID-19 cases reported between 4 January 2020 and 24 February 2020. Setting: News reports and press releases from 50 provinces, regions, and countries outside Wuhan, Hubei province, China. Participants: Persons with confirmed SARS-CoV-2 infection outside Hubei province, China. Measurements: Patient demographic characteristics and dates and times of possible exposure, symptom onset, fever onset, and hospitalization. Results: There were 181 confirmed cases with identifiable exposure and symptom onset windows to estimate the incubation period of COVID-19. The median incubation period was estimated to be 5.1 days (95% CI, 4.5 to 5.8 days), and 97.5% of those who develop symptoms will do so within 11.5 days (CI, 8.2 to 15.6 days) of infection. These estimates imply that, under conservative assumptions, 101 out of every 10 000 cases (99th percentile, 482) will develop symptoms after 14 days of active monitoring or quarantine. Limitation: Publicly reported cases may overrepresent severe cases, the incubation period for which may differ from that of mild cases. Conclusion: This work provides additional evidence for a median incubation period for COVID-19 of approximately 5 days, similar to SARS. Our results support current proposals for the length of quarantine or active monitoring of persons potentially exposed to SARS-CoV-2, although longer monitoring periods might be justified in extreme cases

Enzyme-Synthesized Highly Branched Maltodextrins Have Slow Glucose Generation at the Mucosal α-Glucosidase Level and Are Slowly Digestible In Vivo.

For digestion of starch in humans, α-amylase first hydrolyzes starch molecules to produce α-limit dextrins, followed by complete hydrolysis to glucose by the mucosal α-glucosidases in the small intestine. It is known that α-1,6 linkages in starch are hydrolyzed at a lower rate than are α-1,4 linkages. Here, to create designed slowly digestible carbohydrates, the structure of waxy corn starch (WCS) was modified using a known branching enzyme alone (BE) and an in combination with β-amylase (BA) to increase further the α-1,6 branching ratio. The digestibility of the enzymatically synthesized products was investigated using α-amylase and four recombinant mammalian mucosal α-glucosidases. Enzyme-modified products (BE-WCS and BEBA-WCS) had increased percentage of α-1,6 linkages (WCS: 5.3%, BE-WCS: 7.1%, and BEBA-WCS: 12.9%), decreased weight-average molecular weight (WCS: 1.73×108 Da, BE-WCS: 2.76×105 Da, and BEBA-WCS 1.62×105 Da), and changes in linear chain distributions (WCS: 21.6, BE-WCS: 16.9, BEBA-WCS: 12.2 DPw). Hydrolysis by human pancreatic α-amylase resulted in an increase in the amount of branched α-limit dextrin from 26.8% (WCS) to 56.8% (BEBA-WCS). The α-amylolyzed samples were hydrolyzed by the individual α-glucosidases (100 U) and glucogenesis decreased with all as the branching ratio increased. This is the first report showing that hydrolysis rate of the mammalian mucosal α-glucosidases is limited by the amount of branched α-limit dextrin. When enzyme-treated materials were gavaged to rats, the level of postprandial blood glucose at 60 min from BEBA-WCS was significantly higher than for WCS or BE-WCS. Thus, highly branched glucan structures modified by BE and BA had a comparably slow digesting property both in vitro and in vivo. Such highly branched α-glucans show promise as a food ingredient to control postprandial glucose levels and to attain extended glucose release

Design, synthesis and biological evaluation of 2-nitroimidazopyrazin-one/-es with antitubercular and antiparasitic activity

Tuberculosis and parasitic diseases, such as giardiasis, amebiasis, leishmaniasis and trypanosomiasis, all urgently require improved treatment options. Recently, it has been shown that anti-tubercular bicyclic nitroimidazoles such as pretomanid and delamanid have potential as repurposed therapeutics for the treatment of visceral leishmaniasis. Here we show that pretomanid also possesses potent activity against Giardia lamblia and Entamoeba histolytica, thus expanding the therapeutic potential of nitroimidazo-oxazines. Synthetic analogs with the novel nitroimidazopyrazin-one/-e bicyclic nitroimidazole chemotype were designed, synthesized and structure activity relationships generated. Selected derivatives had potent antiparasitic and antitubercular activity whilst maintaining drug-like properties such as low cytotoxicity against mammalian cell lines (CC50 >100 μM), good metabolic stability in human and mouse liver microsomes and high apparent permeability in a Caco-2 model of intestinal absorption. The kinetic solubility of the new bicyclic derivatives varied, and was found to be a key parameter for future optimization. Taken together, these results suggest promising subclasses of bicyclic nitroimidazoles containing different core architectures have potential for further development

Inter-laboratory multiplex bead-based surface protein profiling of MSC-derived EV preparations identifies MSC-EV surface marker signatures

Mesenchymal stromal cells (MSCs) are promising regenerative therapeutics that primarily exert their effects through secreted extracellular vesicles (EVs). These EVs – being small and non-living – are easier to handle and possess advantages over cellular products. Consequently, the therapeutic potential of MSC-EVs is increasingly investigated. However, due to variations in MSC-EV manufacturing strategies, MSC-EV products should be considered as highly diverse. Moreover, the diverse array of EV characterisation technologies used for MSC-EV characterisation further complicates reliable interlaboratory comparisons of published data. Consequently, this study aimed to establish a common method that can easily be used by various MSC-EV researchers to characterise MSC-EV preparations to facilitate interlaboratory comparisons. To this end, we conducted a comprehensive inter-laboratory assessment using a novel multiplex bead-based EV flow cytometry assay panel. This assessment involved 11 different MSC-EV products from five laboratories with varying MSC sources, culture conditions, and EV preparation methods. Through this assay panel covering a range of mostly MSC-related markers, we identified a set of cell surface markers consistently positive (CD44, CD73 and CD105) or negative (CD11b, CD45 and CD197) on EVs of all explored MSC-EV preparations. Hierarchical clustering analysis revealed distinct surface marker profiles associated with specific preparation processes and laboratory conditions. We propose CD73, CD105 and CD44 as robust positive markers for minimally identifying MSC-derived EVs and CD11b, CD14, CD19, CD45 and CD79 as reliable negative markers. Additionally, we highlight the influence of culture medium components, particularly human platelet lysate, on EV surface marker profiles, underscoring the influence of culture conditions on resulting EV products. This standardisable approach for MSC-EV surface marker profiling offers a tool for routine characterisation of manufactured EV products in pre-clinical and clinical research, enhances the quality control of MSC-EV preparations, and hopefully paves the way for higher consistency and reproducibility in the emerging therapeutic MSC-EV field

Predictors of correct technique in patients using pressurized metered dose inhalers

Background: Correct inhaler technique is recommended by guidelines for optimum asthma care. The objective of the study is to determine real life predictors of correct pressurized metered dose inhaler (pMDI) technique in Asthma and COPD patients. Methods: Two hundred eight adult patients aged 18+ from respiratory outpatients (69.2%) and the community on regular pMDI for a diagnosis of Asthma (78.9%) or COPD, were recruited. A questionnaire containing 31 possible predictors was administered and pMDI technique with or without spacer was observed by trained researchers on 12 point steps, of which 4 were considered critical. Results: 23.1% of patients had no errors in inhaler technique and 32.2% had no critical errors. Patients had a median of 10 correct steps (IQR9-11), and 3(IQR2-4) correct critical steps. Using binary logistic regression the predictors of 10 correct steps were, other healthcare professional (pharmacist, nurse, physiotherapist) explained OR 3.73(1.63–8.54, p = 0.001), male gender 2.70(1.35–5.39, p = 0.004), self-score 1–10 1.21(1.05–1.39, p = 0.007), spacer use 0.38(0.19–0.79, p = 0.007), inhaled steroid 3.71(1.34–10.25, p = 0.01), heart disease 0.31(0.13–0.77, p = 0.01), pneumococcal vaccine 2.48(1.0–6.15, p = 0.043), education level 1–4 1.44(1.00–2.06, p = 0.05) and respiratory physician explained 0–7 times, 1.11(0.99–1.26, p = 0.08). Using ordinal logistic regression, predictors for correct critical steps 0–4, were: technique self-score 1–10 1.2(1.05–1.42, p = 0.006), inhaled corticosteroid use 2.78(1.1–7.31, p = 0.03) and education level 1–4 1.41(1.02–1.95, p = 0.03 Times respiratory physician explained inhaler technique 0–7 1.1(0.98–1.24, p = 0.1), married status 1.55(0.85–2.82, p= 0.15), hypercholesterolaemia 0.52(0.25–1.01, p = 0.054) and male gender 1.76(0.97–3.18, p = 0.06). Conclusions: Known predictors of correct pMDI use, such as gender and education level were confirmed, while age and concomitant use of dry powder inhaler were not. Pneumococcal vaccination and awareness of steroid side effects were possible novel positive predictors, while the use of a spacer and co-morbidity with heart disease were found to be negative predictors. Patients’ self-assessment correlated well with actual performance. This information may be useful in defining approaches to optimize inhaler techniques which are so susceptible to human error.peer-reviewe

Safety, immunogenicity, and reactogenicity of BNT162b2 and mRNA-1273 COVID-19 vaccines given as fourth-dose boosters following two doses of ChAdOx1 nCoV-19 or BNT162b2 and a third dose of BNT162b2 (COV-BOOST): a multicentre, blinded, phase 2, randomised trial

Background Some high-income countries have deployed fourth doses of COVID-19 vaccines, but the clinical need, effectiveness, timing, and dose of a fourth dose remain uncertain. We aimed to investigate the safety, reactogenicity, and immunogenicity of fourth-dose boosters against COVID-19.Methods The COV-BOOST trial is a multicentre, blinded, phase 2, randomised controlled trial of seven COVID-19 vaccines given as third-dose boosters at 18 sites in the UK. This sub-study enrolled participants who had received BNT162b2 (Pfizer-BioNTech) as their third dose in COV-BOOST and randomly assigned them (1:1) to receive a fourth dose of either BNT162b2 (30 µg in 0·30 mL; full dose) or mRNA-1273 (Moderna; 50 µg in 0·25 mL; half dose) via intramuscular injection into the upper arm. The computer-generated randomisation list was created by the study statisticians with random block sizes of two or four. Participants and all study staff not delivering the vaccines were masked to treatment allocation. The coprimary outcomes were safety and reactogenicity, and immunogenicity (antispike protein IgG titres by ELISA and cellular immune response by ELISpot). We compared immunogenicity at 28 days after the third dose versus 14 days after the fourth dose and at day 0 versus day 14 relative to the fourth dose. Safety and reactogenicity were assessed in the per-protocol population, which comprised all participants who received a fourth-dose booster regardless of their SARS-CoV-2 serostatus. Immunogenicity was primarily analysed in a modified intention-to-treat population comprising seronegative participants who had received a fourth-dose booster and had available endpoint data. This trial is registered with ISRCTN, 73765130, and is ongoing.Findings Between Jan 11 and Jan 25, 2022, 166 participants were screened, randomly assigned, and received either full-dose BNT162b2 (n=83) or half-dose mRNA-1273 (n=83) as a fourth dose. The median age of these participants was 70·1 years (IQR 51·6–77·5) and 86 (52%) of 166 participants were female and 80 (48%) were male. The median interval between the third and fourth doses was 208·5 days (IQR 203·3–214·8). Pain was the most common local solicited adverse event and fatigue was the most common systemic solicited adverse event after BNT162b2 or mRNA-1273 booster doses. None of three serious adverse events reported after a fourth dose with BNT162b2 were related to the study vaccine. In the BNT162b2 group, geometric mean anti-spike protein IgG concentration at day 28 after the third dose was 23 325 ELISA laboratory units (ELU)/mL (95% CI 20 030–27 162), which increased to 37 460 ELU/mL (31 996–43 857) at day 14 after the fourth dose, representing a significant fold change (geometric mean 1·59, 95% CI 1·41–1·78). There was a significant increase in geometric mean anti-spike protein IgG concentration from 28 days after the third dose (25 317 ELU/mL, 95% CI 20 996–30 528) to 14 days after a fourth dose of mRNA-1273 (54 936 ELU/mL, 46 826–64 452), with a geometric mean fold change of 2·19 (1·90–2·52). The fold changes in anti-spike protein IgG titres from before (day 0) to after (day 14) the fourth dose were 12·19 (95% CI 10·37–14·32) and 15·90 (12·92–19·58) in the BNT162b2 and mRNA-1273 groups, respectively. T-cell responses were also boosted after the fourth dose (eg, the fold changes for the wild-type variant from before to after the fourth dose were 7·32 [95% CI 3·24–16·54] in the BNT162b2 group and 6·22 [3·90–9·92] in the mRNA-1273 group).Interpretation Fourth-dose COVID-19 mRNA booster vaccines are well tolerated and boost cellular and humoral immunity. Peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose