Transplantation for myelofibrosis patients in the ruxolitinib era: a registry study from the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire

In this SFGM-TC registry study, we report the results after stem cell transplantation (HSCT) in 305 myelofibrosis patients, in order to determine potential risk factors associated with outcomes, especially regarding previous treatment with ruxolitinib. A total of 102 patients were transplanted from an HLA-matched-sibling donor (MSD), and 143 patients received ruxolitinib. In contrast with previous studies, our results showed significantly worse outcomes for ruxolitinib patients regarding overall survival (OS) and non-relapse mortality (NRM), especially in the context of unrelated donors (URD). When exploring reasons for potential confounders regarding the ruxolitinib effect, an interaction between the type of donor and the use of ATG was found, therefore subsequent analyses were performed separately for each type of donor. Multivariable analyses did not confirm a significant negative impact of ruxolitinib in transplantation outcomes. In the setting of URD, only age and Fludarabine-Melphalan (FM) conditioning were associated with increased NRM. For MSD, only Karnoksfy <70% was associated with reduced OS. However, a propensity score analysis showed that ruxolitinib had a negative impact on OS but only in non-responding patients, consistent with previous data. To conclude, with all the precautions due to confounders and bias, ruxolitinib itself does not appear to increase mortality after HSCT.

Influence of preoperative aortic regurgitation on long-term autograft durability and dilatation in children and adolescents undergoing the Ross procedure

OBJECTIVE

Primary aortic insufficiency (AI) is a risk factor for autograft reintervention in adults undergoing the Ross procedure. We sought to examine the influence of preoperative AI on autograft durability in children and adolescents.

METHODS

From 1993 to 2020, 125 consecutive patients between ages 1 and 18 underwent a Ross procedure. The autograft was implanted using a full-root technique in 123 (98.4%) and included in a polyethelene terephthalate graft in 2 (1.6%). Patients with aortic stenosis (aortic stenosis group) (n = 85) were retrospectively compared with those with AI or mixed disease (AI group) (n = 40). Median length of follow-up was 8.2 years (interquartile range, 3.3-15.4 years). The primary end point was the incidence of severe AI or autograft reintervention. Secondary end points included changes in autograft dimensions analyzed using mixed-effect models.

RESULTS

The incidence of severe AI or autograft reintervention was 39.0% ± 13.0% in the AI group and 8.8% ± 4.4% in the aortic stenosis group at 15 years (P = .02). Annulus z scores increased in both aortic stenosis and AI groups over time (P < .001). However, the annulus dilated at a faster rate in the AI group (absolute difference, 3.8 ± 2.0 vs 2.5 ± 1.7; P = .03). Sinus of Valsalva z scores increased in both groups as well (P < .001), but at similar rates over time (P = .11).

CONCLUSIONS

Children and adolescents with AI undergoing the Ross procedure have higher rates of autograft failure. Patients with preoperative AI have more pronounced dilatation at the annulus. Akin to adults, a surgical aortic annulus stabilization technique that modulates growth is needed in children.

Aortic insufficiency following balloon aortic valvuloplasty does not impact long-term autograft durability after the Ross procedure

OBJECTIVE

Preoperative aortic insufficiency (AI) is associated with inferior autograft durability after the Ross procedure. However, many patients with aortic stenosis (AS) undergo balloon aortic valvuloplasty (BAV) early and present with longstanding AI before Ross. We studied how BAV and subsequent valvular pathology impacts autograft durability.

METHODS

Patients undergoing the Ross operation from 1993 to 2020 were identified. Those who underwent BAV before Ross were compared with patients who did not undergo BAV and underwent Ross for predominant AI (AI group) or AS (AS group). Those who underwent previous open surgical aortic valve intervention were excluded. Primary outcome of interest was autograft failure, defined as a composite of autograft reintervention or severe insufficiency.

RESULTS

A total of 198 patients were included. Seventy-nine (39.9%) underwent BAV and subsequently underwent the Ross for predominant AI (45.6%) or AS (54.4%). Of patients who did not undergo BAV, 66 (33.3%) presented with predominant AI and 53 (26.8%) with AS. Freedom from autograft failure at 15 years was 90%, 92%, and 62% in BAV, AS, and AI groups, respectively. The AI group was at significantly increased risk of long-term autograft failure (hazard ratio, 5.6; P = .01), whereas the AS and BAV groups had similar, low risk (hazard ratio, 1.1; P = .91). Autograft durability was similar among patients who received BAV and presented with AS or AI before the Ross (P = .84).

CONCLUSIONS

BAV before the Ross procedure is common in patients with AS. These patients have excellent long-term autograft durability regardless of preoperative valvular pathology and should strongly be considered for the Ross operation.

A Knife Penetrating the Right Ventricle, Interventricular Septum, and 2 Valves: A Case Report

Penetrating chest trauma may result in significant intracardiac injury. A traumatic ventricular septal defect is a rare complication that requires surgical management, particularly if heart failure ensues. We report a case of delayed repair of an outlet-type ventricular septal defect and perforation of the aortic and pulmonary valve leaflets following a stab wound. This report highlights diagnostic and surgical considerations and also presents an opportunity to review the conotruncal anatomy, which may be relatively unfamiliar to many adult cardiac surgeons.

Inhibitory Fc-Gamma IIb Receptor Signaling Induced by Multivalent IgG-Fc Is Dependent on Sialylation

Immunoglobulin (IgG) Fc glycosylation has been shown to be important for the biological activity of antibodies. Fc sialylation is important for the anti-inflammatory activity of IgGs. However, evaluating the structure-activity relationship (SAR) of antibody Fc glycosylation has been hindered using simplified in vitro models in which antibodies are often displayed in monomeric forms. Presenting antibodies in monomeric forms may not accurately replicate the natural environment of the antibodies when binding their antigen in vivo. To address these limitations, we used different Fc-containing molecules, displaying their Fc domains in monovalent and multivalent fashion. Given the inhibitory role of Fc gamma receptor IIb (FcγRIIb) in autoimmune and inflammatory diseases, we focused on evaluating the impact of Fc sialylation on the activation of FcγRIIb. We report for the first time that in human cellular systems, sialic acid mediates the induction of FcγRIIb phosphorylation by IgG-Fc when the IgG-Fc is displayed in a multivalent fashion. This effect was observed with different types of therapeutic agents such as sialylated anti-TNFα antibodies, sialylated IVIg and sialylated recombinant multivalent Fc products. These studies represent the first report of the specific effects of Fc sialylation on FcγRIIb signaling on human immune cells and may help in the characterization of the anti-inflammatory activity of Fc-containing therapeutic candidates.

Climate Change as a Social Determinant of Health: An Interactive Case-Based Learning Activity

Introduction

Despite consensus on climate change's impact on humans, medical schools have not widely adopted inclusion of environmental topics into their mandatory curriculum. This educational activity explicitly addresses climate change as one of the environmental determinants of health (EDH).

Methods

We developed a required, 1-hour module for all first-year medical students. This interactive, case-based, small-group activity was incorporated into a curriculum within an advising program but could be run independently. Before and after the session, participants completed evaluations assessing knowledge gains and attitude shifts.

Results

Of 183 first-year students, 155 completed both pre- and postmodule surveys. Participants' rating increased on the postmodule survey item "priority should be given to the discussion of EDH in medical education." The Wilcoxon signed rank test determined this difference in priority was statistically significant (p < .001). Reported strengths of this activity included the cases, informative content on EDH, the video, the discussion, and highlighted EDH resources. Suggested areas for improvement included more information on how to apply concepts to clinical contexts, guidance on how to engage in EDH concepts, and more discussion time. As a result of the module, students planned to engage in recycling, reduced consumption, advocacy, and changes to mode of transportation.

Discussion

Climate change remains the greatest global threat to human health, and future physicians must be equipped to educate patients and policymakers on the harms of environmental hazards. This brief yet effective module offers one approach to incorporating this topic into medical school curricula.

Evaluation of the relevance of the growth modulation index (GMI) from the FFCD 0307 randomized phase III trial comparing the sequence of two chemotherapeutic regimens

BACKGROUND

Precision medicine trials disrupted the paradigm of randomized controlled trials in large populations. Patient selection may be based on molecular alterations rather than on primary tumor location. In small patient populations, the growth modulation index (GMI) has been developed to evaluate treatment efficacy by using each patient as its own control. The FFCD 0307 randomized phase III trial compared two sequences of chemotherapy in advanced gastric cancer, which represents a unique opportunity to evaluate the relevance of the GMI.

PATIENTS AND METHODS

In the FFCD 0307 trial, patients with advanced gastric cancer were randomized between two chemotherapy sequences [ECX followed by FOLFIRI at disease progression (arm A) versus FOLFIRI followed by ECX (arm B)]. GMI was defined as the ratio of the progression-free survival on second treatment (PFS2) to the time to progression on first treatment (TTP1). Sequence benefit was defined as a GMI exceeding 1.3 (GMI-high). GMI was correlated with overall survival (OS). OS1 and OS2 were measured from first randomization and second-line failure to death.

RESULTS

Four hundred and sixteen patients were randomized (209 in arm A, 207 in arm B). One hundred and seventy-five patients (42%) received the two sequences and were assessable for GMI (97 in arm A, 79 in arm B). The median GMI was higher in arm A than in arm B (0.62 versus 0.47, P = 0.04). Patients with a high GMI had a longer OS1 (median 14.9 versus 11.5 months, NS). Median OS2 was doubled in the GMI-high group (3.4 versus 1.6 months, NS).

CONCLUSION

GMI analyses suggest that ECX followed by FOLFIRI might represent a better therapeutic strategy than FOLFIRI followed by ECX. High GMI was associated with prolonged survival.

Pediatric private practice in the Nord-Pas-de-Calais region: Demographics, organization, and challenges

While the needs for pediatric care are increasing and becoming more diverse, pediatric private practice in France is encountering difficulties linked to a growing medical demographic deficit. The objective of this study was to give an overview of pediatric private practice in the Nord-Pas-de-Calais region and to describe the main challenges encountered.

METHODS

For this descriptive observational survey, private practice pediatricians in the Nord-Pas-de-Calais region filled out an online questionnaire between April 2019 and October 2020.

RESULTS

The response rate was 64%. Most respondents practiced in an urban area (87%) and shared the practice with other physicians (59%). A majority (85%) had previously worked in hospital; 65% reported training in a subspecialty. Overall, 48% had other professional activities; 28% worked night shifts and 96% accepted urgent requests for consultations. A total of 33% reported having difficulties contacting specialists for consults, and 46% had difficulties in obtaining written reports of their patients' hospitalizations. All respondents participated in a form of ongoing medical education. The main difficulties were: lack of information about how to found a private practice (68%), lack of personal time (61%), balance between medical and administrative work (59%), and an excess of patients to care for (57%). The main satisfactions were: trusting relationships with patients (98%), freedom in their choice of practice (85%), and the diversity of problems and situations encountered (68%).

CONCLUSION

Our study underlines that private practice pediatricians are involved in healthcare provision, in particular regarding ongoing medical training, subspecialties, and continuity of care. It also highlights the problems encountered and the possible improvements: developing better communication between private practice and hospitals, reinforcing training during residency, and highlighting the importance and complementarity of private practice in children's healthcare.

Comparative outcomes and risk analysis after cone repair or tricuspid valve replacement for Ebstein's anomaly

Objective

Ebstein's anomaly is a rare congenital heart malformation for which surgical and medical management are still controversial. The cone repair has transformed surgical outcomes in many of these patients. We aimed to present our results on the outcomes of patients with Ebstein's anomaly who underwent a cone repair or tricuspid valve replacement.

Methods

A total of 85 patients who underwent a cone repair (mean age, 16.5 years) or tricuspid valve replacement (mean age, 40.8 years) between 2006 and 2021 were included. Univariate, multivariate, and Kaplan-Meier analyses were used to evaluate operative and long-term outcomes.

Results

Residual/recurrent greater than mild-to-moderate tricuspid regurgitation at discharge was higher after cone repair compared with tricuspid valve replacement (36% vs 5%; P = .010). However, at last follow-up, the risk of greater than mild-to-moderate tricuspid regurgitation was not different between groups (35% in the cone group vs 37% in the tricuspid valve replacement group; P = .786). The tricuspid valve replacement group had a higher risk of tricuspid valve reoperation (37% vs 9%; P = .005) and tricuspid stenosis (21% vs 0%; P = .002) compared with the cone repair group. Kaplan-Meier freedom from reintervention was 97%, 91%, and 91% at 2, 4, and 6 years after cone repair, respectively, and 84%, 74%, and 68% at 2, 4, and 6 years after tricuspid valve replacement, respectively (P = .0191). At last follow-up, right ventricular function was significantly worse from baseline in the tricuspid valve replacement group (P = .0294). There were no statistical differences between age-stratified cohorts or surgeon volume in the cone repair group.

Conclusions

The cone procedure offers excellent results, with stable tricuspid valve function and low reintervention and death rates at last follow-up. The rate of greater than mild-to-moderate residual tricuspid regurgitation at discharge was higher after cone repair compared with tricuspid valve replacement, but this did not expose the patient to a higher risk of reoperation or death at last follow-up. Tricuspid valve replacement was associated with a significantly higher risk of tricuspid valve reoperation and tricuspid valve stenosis, and worse right ventricular function at last follow-up.

Inclusion of Vietnamese Americans: Opportunities to understand dementia disparities

There is a dearth of research on cognitive aging and dementia in Asian Americans, particularly Vietnamese Americans, who are the fourth largest Asian subgroup in the United States. The National Institutes of Health is mandated to make certain that racially and ethnically diverse populations are included in clinical research. Despite the widespread recognition to ensure that research findings can be generalizable to all groups, there are no estimates of the prevalence or incidence of mild cognitive impairment and Alzheimer's disease and related dementias (ADRD) in Vietnamese Americans, nor do we understand ADRD risk and protective factors in this group. In this article, we posit that studying Vietnamese Americans contributes to a better understanding of ADRD in general and offers unique opportunities for elucidating life course and sociocultural factors that contribute to cognitive aging disparities. That is, the unique context of Vietnamese Americans may provide understanding in terms of within-group heterogeneity and key factors in ADRD and cognitive aging. Here, we provide a brief history of Vietnamese American immigration and describe the large but often ignored heterogeneity of Asian Americans in the United States, elucidate how early life adversity and stress might influence late-life cognitive aging, and provide a basis for the role of sociocultural and health factors in the study of Vietnamese cognitive aging disparities. Research with older Vietnamese Americans provides a unique and timely opportunity to more fully delineate the factors that contribute to ADRD disparities for all populations.

A 16-month-long experience of COVID-19 in allogeneic haematopoietic stem cell transplantation recipients: An SFGM-TC multicentre cohort study

This 16-month-long multicentre retrospective study of 225 allogeneic haematopoietic stem cell transplantation (alloHSCT) recipients with COVID-19 examines risk factors for severity and mortality, describing the successive waves of infections (from March to June 2020 and from August 2020 to June 2021). We confirm the negative role of low respiratory tract disease and immunosuppressive treatment. We highlight significantly lower percentages of severe forms and COVID-19-related mortality during the second wave. Monthly comparative evolution of cases in alloHSCT recipients and in the French population shows a higher number of cases in alloHSCT recipients during the first wave and a decrease from February 2021.

Structural Study of Potent Triazole-Based Inhibitors of Staphylococcus aureus Biotin Protein Ligase

The rise of multidrug-resistant bacteria, such as Staphylococcus aureus, has highlighted global urgency for new classes of antibiotics. Biotin protein ligase (BPL), a critical metabolic regulatory enzyme, is an important target that shows significant promise in this context. Here we report the in silico docking, synthesis, and biological assay of a new series of N1-diphenylmethyl-1,2,3-triazole-based S. aureus BPL (SaBPL) inhibitors (8-19) designed to probe the adenine binding site and define whole-cell activity for this important class of inhibitor. Triazoles 13 and 14 with N1-propylamine and -butanamide substituents, respectively, were particularly potent with K i values of 10 ± 2 and 30 ± 6 nM, respectively, against SaBPL. A strong correlation was apparent between the K i values for 8-19 and the in silico docking, with hydrogen bonding to amino acid residues S128 and N212 of SaBPL likely contributing to potent inhibition.

The use of antibiotics in acute oral health patients presenting at public dental clinics in the Western Sydney region

BACKGROUND

There is a limited need for antibiotics when treating oral health problems, yet they are often prescribed, increasing risk of antimicrobial resistance (AMR). With AMR a threat to public health, the objectives of this study were to assess the frequency, suitability, and factors associated with antibiotic prescriptions for acute dental problems across Greater Western Sydney public dental clinics.

METHODS

Patients' reason for attending, details of any antibiotics use, and the treating dental practitioner's clinical examination and diagnosis were compared to current prescribing guidelines, and logistic regression was used to identify predictors of antibiotic prescription.

RESULTS

In all, 1,071 patients participated in the study, and 15.9% reported to using antibiotics for their dental problem. Over three-quarters obtained the antibiotics from their general medical practitioner (GMP). A high prevalence of antibiotics were not indicated for the patient's complaint (71.8%) including for those with a history of extraction, pain, or intraoral swelling, who had significantly higher odds of antibiotic prescription (OR > 9). The antibiotic type prescribed was generally suitable.

CONCLUSIONS

In summary, the data suggest that the majority of antibiotics were inappropriately prescribed for the patient's dental complaints and there is a need for interventions to improve compliance with antibiotic prescribing guidelines.

Characteristics and outcomes of patients presenting with out of hospital cardiac arrest to a regional hospital

Funding Acknowledgements

Type of funding sources: None.

Introduction

Out of hospital cardiac arrest (OHCA) carries a high rate of mortality and can be due to cardiac or non-cardiac causes. We reviewed consecutive patients presenting with OHCA to the emergency department of a regional hospital in Australia, between January 2019 and March 2022. Medical records were reviewed to assess presenting rhythm, final diagnosis, risk factors known at time of presentation, results of cardiac investigations and survival to hospital discharge.

Results

Over the study period, 107 patients presented with cardiac arrest, with an average age of 67 years (range 29 to 95 years). Most patients were male (70, 67%), although in those with a non-cardiac cause identified only 53% were male. An underlying cardiac cause was identified in 50 (47%), a non-cardiac cause was identified in 18 (17%), and 39 (36%) had no identifiable cause. The most common cardiac causes were ST-elevation myocardial infarction (18, 36%), followed by non-ischaemic cardiomyopathy (9, 18%) and scar-related arrhythmia (7, 14%). Overall, ischaemic heart disease was responsible for 31 (62%) cases. Coronary angiography was performed in 36 (72%) of cardiac cases. Those who were diagnosed with ST-elevation myocardial infarction had an average time from presentation to coronary angiography of 61 minutes while the average was 38 hours for all patients presenting with OHCA. The most common presenting rhythm was ventricular fibrillation (39, 38%). The overall mortality rate was 61% for all OHCA. Among those with a cardiac cause, a non-cardiac cause or no cause identified for the OHCA, the mortality rates were 32%, 87% and 87% respectively. Data published by the regional Ambulance Service show that the survival to discharge from hospital of 39% in our regional hospital is comparable with state-wide outcomes.

Discussion

These data reflect the significant mortality and wide spectrum of disease underlying OHCA, and thus the challenge of managing patients presenting with OHCA. Cardiac disease accounts for almost half of all cases of OHCA, and also encompasses a wide spectrum of disease. However, the mortality in patients with OHCA due to an underlying cardiac cause, while still significant, is better than those patients in whom no cardiac cause is identified.

"Aging is beautiful and graceful:" Exploring college students' perceptions of aging, older adults, and future older selves

Perception of one's own age and the aging process can influence healthy aging and encourage younger adults to be more proactive in taking care of themselves. There is a shortage of literature on college students' self-perceptions of aging and old age. This descriptive qualitative study explored how short-term aging research training and activities influenced college students' perceptions of aging, older adults, and their future older selves. Students were exposed to discussions about aging, the aging process, myths, a brief TED talk, and a video on positive age stereotypes in preparation for their encounter with older adults in a more extensive photovoice aging research project. Data for the study were collected using weekly guided reflections and drawing. Findings show that college students improved perceptions of aging and older adults after the short-term research training. We found cultural differences in self-perception of the onset of old age. Students perceived healthy aging in terms of biological, psychological, spiritual, and social dimensions of health. Students presented a hopeful, positive picture of their future older self as opposed to the negative stereotypic views they initially had of older adults. Reflections on one's own aging may be crucial in encouraging younger adults to be more proactive in taking care of themselves for a healthier life in later adulthood.

Characterizing and predicting the relationship between translaminar fracture toughness and pull-out length distributions under distinct temperatures

The translaminar fracture toughness reflects the damage tolerance of a fibre-reinforced composite under longitudinal tension, which often governs the final failure of structures. One of the main energy-dissipation mechanisms that contributes to the translaminar toughness of composites is the fibre pull-out process. The present study aims to quantify and model the statistical distribution of fibre pull-out lengths formed on the translaminar fracture surface of composites, for the first time in the literature; this is done under different temperatures, so that the relationship between pull-out length distributions, micromechanical properties and the translaminar fracture toughness can be established. The fracture surfaces of cross-ply compact tension specimens tested under three different temperatures have been scanned through X-ray computed tomography to quantify the extent of fibre pull-out on the fracture surfaces; the distribution of pull-out lengths showed alarger average and larger variability with an increase in temperature, which also lead to an increase in translaminar fracture toughness. A similar trend has been captured by the proposed analytical model, which predicts the pull-out length distribution based on the analysis of quasi-fractal idealizations of the fracture surface, yielding an overall accuracy of more than 85%. This article is part of the theme issue 'Ageing and durability of composite materials'.

84. One-month Humoral Response Following Two Doses of Covid-19 Vaccines in Specific populations – ANRS0001S COV POPART Cohort Study

Background

We evaluated the immune response to COVID-19 vaccines in several specific populations at high risk of severe COVID-19.

Methods

Participants from the French national multi-center prospective cohort study ANRS0001S COV-POPART were included (11 specific subpopulations: and 2 control groups (18–64 years and over 65 years)). In this preliminary analysis patients and controls who had received at least two vaccine doses have been included. Percentages (95% confidence intervals (CI)) of participants with anti-Spike SARS-CoV-2 IgG antibodies (ELISA) and specific neutralizing antibodies (in vitro neutralization assay) were evaluated at one month after the second dose of COVID-19 vaccine.

Results

3703 were included: 2650 participants from specific subpopulations (171 solid cancers, 160 SOT, 100 HCT, 91 chronic renal failures, 141 systemic autoimmune diseases, 157 autoimmune inflammatory rheumatic diseases, 361 multiple sclerosis (MS) or neuromyelitis optica spectrum disorders, 61 hypogammaglobulinemia, 401 diabetic, 739 obeses non-diabetic and 476 HIV) and 1053 controls (893: 18–64 years and 160 over 65 years). Median age was 51.7 years [InterQuartile range: 40.8 – 60.9] and 50.7% were male. Most of the participants received BNT162b2 vaccine (86.4%). In the control group, 100% (95%CI: 99.6;100.0) of those aged 18–64 and 99.4% (96.6; 100.0) of those over 65 years developed anti-Spike IgG antibodies.

PLWHIV, cancer and diabetic patients had high rate of responders after two doses with 98.3% (97.2;99.1), 93.0% (88.1;96.3) and 92.0% (88.9;94.5), respectively. The lowest percentage of responders was found in patients with SOT (13.8% (8.8;20.1), HSCT (34.0% (24.8;44.2) and hypogammaglobulinemia (52.5% 39.3;65.4). In both control groups, the frequency of neutralizing antibodies was similar to the anti-Spike IgG antibody response. In the immunodeficient populations, neutralizing antibodies responders tended to be less frequent than anti-Spike antibodies responders. Similar trends than for IgG antibody were identified (Figure 1).

Anti-Spike and Neutralizing antibody (Ab) responses (95% CI) one month after the second dose of COVID-19 vaccine in specific and control populations.

Conclusion

Lower COVID-19 vaccine humoral response was observed in specific populations than in controls, especially in patients with hypogammaglobulinemia, HSCT and SOT.

Disclosures

Paul LOUBET, MD, PhD, pfizer: Board Member Odile Launay, MD, PhD, AstraZeneca: Financial|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|Johnson & Johnson: Advisor/Consultant|Johnson & Johnson: Grant/Research Support|MD: Advisor/Consultant|Moderna: Advisor/Consultant|MSD: Data safety monitoring board|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant|Sanofi Pasteur: Grant/Research Support|Sanofi Pasteur: Data safety monitoring board.

A New 1,2,3-Triazole Scaffold with Improved Potency against Staphylococcus aureus Biotin Protein Ligase

Staphylococcus aureus, a key ESKAPE bacteria, is responsible for most blood-based infections and, as a result, is a major economic healthcare burden requiring urgent attention. Here, we report in silico docking, synthesis, and assay of N1-diphenylmethyl triazole-based analogues (7-13) designed to interact with the entire binding site of S. aureus biotin protein ligase (SaBPL), an enzyme critical for the regulation of gluconeogenesis and fatty acid biosynthesis. The second aryl ring of these compounds enhances both SaBPL potency and whole cell activity against S. aureus relative to previously reported mono-benzyl triazoles. Analogues 12 and 13, with added substituents to better interact with the adenine binding site, are particularly potent, with K_i values of 6.01 ± 1.01 and 8.43 ± 0.73 nM, respectively. These analogues are the most active triazole-based inhibitors reported to date and, importantly, inhibit the growth of a clinical isolate strain of S. aureus ATCC 49775, with minimum inhibitory concentrations of 1 and 8 μg/mL, respectively.

Technology Usage and Impacts by COVID-19 among Patients in a Radiation Oncology Clinic

Purpose/Objective(s)

Mobile devices provide platforms for consistent and real time symptom tracking for cancer patients, allowing for better symptom reporting and more timely interventions. There is limited research investigating barriers to adoption within the oncology setting and COVID-19 impacts on patent willingness to use health technology. Understanding these issues is key to successful development and implementation. We designed a survey to assess patient willingness and barriers to using mobile devices to report/track symptoms (e-report).

Materials/Methods

Two cohorts of adult patients completed a 21-question anonymized survey. The survey was administered to clinic patients before (PRE) and 18mo after (POST) the start of the COVID pandemic. Three additional questions were added to POST survey to investigate impacts from COVID. Demographics, technology usage, willingness to report data, barriers to utilization, and changes due to COVID were evaluated using descriptive statistics. Predictors of willingness to e-report, barriers to use, and changes due to the COVID-19 pandemic were analyzed using univariate and multivariate logistic regression (MVA).

Results

318 patients completed the survey (PRE= 144 patients; POST= 174 patients) with mean age 65y, 75% Caucasian, 55% male. Altogether, 75% used a smart phone (PRE=66.7%; POST=81.3%; p 0.003), 90% reported home internet access (PRE=87.5%; POST=91.4%; p 0.259), 86% used a computer (PRE=79.2%; POST=90.8%; p 0.004), and 26% used a wearable health tracker (PRE 25.7%; POST 26.4%; p 0.881). On MVA, age>65 (OR 0.32; p 0.001), annual income>50K (OR 2.16; p 0.032), smart phone ownership (OR 4.07; p 0.000), and new/current patient status (OR 2.15; p 0.020) were all significant factors impacting willingness to e- report. Limited tech literacy (p 0.024) and time commitment (p 0.048) were the only significant barriers. Privacy as a barrier was greater in PRE vs POST cohort (OR 2.3 vs OR 1.1) trending toward significance. Nearly all modes of tech usage were greater in POST vs PRE cohort. POST cohort was significantly more willing to e- report (81.1% vs 69.1%; OR 1.91; p 0.016). This remained significant on MVA after adjusting for age, concern for privacy, tech literacy, and patient status (OR 1.88; p 0.026). Furthermore, 51% of POST cohort reported the pandemic directly influenced their willingness to e-report (40% more, 11% less).

Conclusion

Radiation oncology patients are willing to use mobile technology to report symptoms. Willingness increases with decreasing age, increasing annual income, smartphone ownership, and new/current patient status. Significant barriers include tech literacy and time commitment. Post-pandemic patients are more willing to e-report and list fewer barriers. The COVID-19 pandemic appears to have had a positive impact on technology usage by patients. Efforts to develop and test mobile applications for this population are justified.

High tumor burden before blinatumomab has a negative impact on the outcome of adult patients with B-cell precursor acute lymphoblastic leukemia. A real-world study by the GRAALL

Blinatumomab is a bispecific T-cell engager approved for B-cell precursor acute lymphoblastic leukemia (B-ALL) with persistent minimal residual disease (MRD) or in relapse. The prognostic impact of tumor load has been suggested before other immunotherapies but remains poorly explored before blinatumomab. We retrospectively analyzed the outcome of 73 patients who received blinatumomab either in first complete remission (CR) with MRD (n=35) or at relapse (n=38). Among MRD patients, 91% had MRD >0.01% before blinatumomab, and 89% achieved complete MRD response after blinatumomab. High pre-blinatumomab MRD levels were associated with shorter relapse-free survival (P=0.049) and overall survival (OS) (P=0.011). At 3 years, OS was 33%, 58% and 86% for pre-blinatumomab MRD >1%, between MRD 0.1-1% and <0.1% respectively. Among relapsed patients, 23 received blinatumomab with overt relapse and 15 were in complete response (CR) after bridging chemotherapy. At 3 years, overall CR rate was 68% and complete MRD response rate was 84%. Patients who directly received blinatumomab had shorter relapse-free survival (P=0.033) and OS (P=0.003) than patients bridged to blinatumomab. Three-year OS was 66% in the latter group compared to 16% in the former group. Our observations suggest that pre-blinatumomab tumor burden should help to design more tailored strategies including tumor load reduction in relapsed patients.

Structural insights into the antifungal drug target guanosine monophosphate synthase from Aspergillus fumigatus

Purine biosynthesis is a fundamental cellular process that sustains life by maintaining the intracellular pool of purines for DNA/RNA synthesis and signal transduction. As an integral determinant of fungal survival and virulence, the enzymes in this metabolic pathway have been pursued as potential antifungal targets. Guanosine monophosphate (GMP) synthase has been identified as an attractive target as it is essential for virulence in the clinically prominent fungal pathogens Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans. However, a lack of structural information on GMP synthase has hindered drug-design efforts. Here, the first structure of a GMP synthase of fungal origin, that from A. fumigatus (at 2.3 Å resolution), is presented. Structural analysis of GMP synthase shows a distinct absence of the D1 dimerization domain that is present in the human homologue. Interestingly, A. fumigatus GMP synthase adopts a dimeric state, as determined by native mass spectrometry and gel-filtration chromatography, in contrast to the monomeric human homologue. Analysis of the substrate-binding pockets of A. fumigatus GMP synthase reveals key differences in the ATP- and XMP-binding sites that can be exploited for species-specific inhibitor drug design. Furthermore, the inhibitory activities of the glutamine analogues acivicin (IC50 = 16.6 ± 2.4 µM) and 6-diazo-5-oxo-L-norleucine (IC50 = 29.6 ± 5.6 µM) against A. fumigatus GMP synthase are demonstrated. Together, these data provide crucial structural information required for specifically targeting A. fumigatus GMP synthase for future antifungal drug-discovery endeavours.

Differences in antimicrobial susceptibility testing complicating management of IMP carbapenemase-producing Enterobacterales infection

OBJECTIVES

IMP-type carbapenemases are rarely detected in Europe and limited information is available to guide the treatment of infections caused by carbapenemase-producing Enterobacterales (CPE) producing these carbapenemases. Accurate antimicrobial susceptibility testing (AST) results are essential for optimal antibiotic management. Here we report discrepancies in AST of IMP-producing Enterobacterales (IMP-CPE) complicating the management of severe sepsis.

METHODS

Antimicrobial susceptibilities were analysed by in-house VITEK® 2, Etest and broth microdilution (BMD). Carbapenemase-encoding genes were detected by PCR. Whole-genome sequencing (WGS) was performed using an Illumina MiSeq platform.

RESULTS

Minimum inhibitory concentrations (MICs) determined by VITEK® 2 for Enterobacter hormaechei and Klebsiella oxytoca blood culture isolates were ≥16 mg/L for meropenem and ≤0.5 mg/L for ertapenem. In contrast, Etest analysis and BMD returned MICs of 2 mg/L and 1 mg/L, respectively. Both isolates tested positive for IMP carbapenemase-encoding genes by PCR. WGS revealed that both isolates carried the same bla_IMP-4 gene. Based on VITEK® 2 susceptibilities, initial treatment was with tigecycline and amikacin. After subsequent deterioration, the patient was successfully treated with ertapenem and amikacin.

CONCLUSION

This case highlights that automated AST by VITEK® 2 can over-report meropenem resistance for IMP carbapenemase-producers compared with Etest and BMD. Clinicians need to be cautious deciding against carbapenem treatment based on VITEK® 2 susceptibility testing results for IMP-positive Enterobacterales. Tigecycline was inferior to carbapenem treatment for pyelonephritis caused by isolates expressing IMP carbapenemases, however specific evidence guiding the treatment of these infections is lacking.

Patient Engagement With Urologists on Social Media in a Community Practice

Background

Based on the Boston Area Community Health Survey, 52 million adults in the United States will have lower urinary tract symptoms, urine leakage, painful bladder syndrome, and prostatitis, which may parallel the prevalence of cardiovascular disease. In the year 2000, benign prostatic hyperplasia (BPH) accounted for 117,000 emergency department visits and 105,000 hospitalizations. These numbers underscore the burden of urological conditions and highlight the importance of patient education in preventing unnecessary hospitalizations and emergency department visits. Certain factors that may alter the progression and severity of disease include physical activity and other lifestyle changes. Based on current trends, patient education via social media may be an invaluable tool in limiting the burden on urologists and the healthcare system in the future.

Aims

This study aims to determine whether patients in a community urology practice would engage with their urologists over social media and if the likelihood to engage was associated with various demographic factors. Furthermore, the likelihood to engage actively (defined as commenting/sharing) versus passively (defined as liking a post) on two different topics within the scope of urology was determined. The two topics used were erectile dysfunction (ED)/urinary incontinence and kidney stone prevention.

Methods

Participants were recruited from a community urologic clinic in Alabama. During the month of April 2021, 293 participants completed a survey that included basic demographic questions as well as questions with a visual analog 5-point Likert scale. Responses on the Likert scale were given a value of one (very unlikely) to five (very likely), and a two-tailed Mann-Whitney U test with an α of 0.05 was used to determine significance in differences of responses. In the case of ties, the mid-rank method was used to assign ranks. For analysis of the Likert scale responses, only those respondents who had social media accounts were included.

Results

Overall, respondents were more likely to interact with a post by their urologist passively engage rather than actively. They were also less likely to passively and actively engage on a topic concerning ED/urinary incontinence versus kidney stone prevention. On the topic of kidney stone prevention, respondents were less likely to engage actively than passively. There was no difference in the likelihood of actively or passively engaging on the topic of ED/urinary incontinence. Compared to men, women were more likely to actively and passively engage on social media. On the topic of ED/urinary incontinence, women were more likely than men to actively engage; however, there was no difference in passive engagement. On the topic of kidney stone prevention, women were more likely to actively and passively engage. When looking at the likelihood of engagement based on age, there was no difference in active or passive engagement between those 55 and under or older than 55. This held true when data were stratified by topic.

Conclusion

Based on these results, the maximum impact of a social media page from a urological practice would be gained by focusing on preventative practices for less sensitive urological conditions. Furthermore, the data suggests that as the population of social media users continues to age, physicians should not expect a change in engagement patterns anytime soon.

Sperm Cyst "Looping": A Developmental Novelty Enabling Extreme Male Ornament Evolution

Postcopulatory sexual selection is credited as a principal force behind the rapid evolution of reproductive characters, often generating a pattern of correlated evolution between interacting, sex-specific traits. Because the female reproductive tract is the selective environment for sperm, one taxonomically widespread example of this pattern is the co-diversification of sperm length and female sperm-storage organ dimension. In Drosophila, having testes that are longer than the sperm they manufacture was believed to be a universal physiological constraint. Further, the energetic and time costs of developing long testes have been credited with underlying the steep evolutionary allometry of sperm length and constraining sperm length evolution in Drosophila. Here, we report on the discovery of a novel spermatogenic mechanism—sperm cyst looping—that enables males to produce relatively long sperm in short testis. This phenomenon (restricted to members of the saltans and willistoni species groups) begins early during spermatogenesis and is potentially attributable to heterochronic evolution, resulting in growth asynchrony between spermatid tails and the surrounding spermatid and somatic cyst cell membranes. By removing the allometric constraint on sperm length, this evolutionary innovation appears to have enabled males to evolve extremely long sperm for their body mass while evading delays in reproductive maturation time. On the other hand, sperm cyst looping was found to exact a cost by requiring greater total energetic investment in testes and a pronounced reduction in male lifespan. We speculate on the ecological selection pressures underlying the evolutionary origin and maintenance of this unique adaptation.

Cyclophosphamide and prednisolone for chemotherapy naïve B cell multicentric lymphoma in dogs: 32 cases (2017-2021)

OBJECTIVES

The aim of this study was to characterise the response rate and toxicity profile of cyclophosphamide and prednisolone given to dogs with newly diagnosed, chemotherapy naïve, B cell multicentric lymphoma.

MATERIALS AND METHODS

Dogs with diagnosed with B cell lymphoma naïve to chemotherapy treatment were prospectively identified at the author's institution (2017 to 2021) and given cyclophosphamide as their initial chemotherapeutic agent in combination with prednisolone with owner's consent. Signalment, laboratory findings, stage, treatment response and toxicity were recorded.

RESULTS

Thirty-two dogs were included in the study. The overall response rate in this population of dogs was 84%. Twenty dogs (62%) had a partial response, three dogs (9%) had a complete response, four dogs (12%) had stable disease and five dogs (15%) had progressive disease. Side effects were noted in 47% of patients, with neutropaenia being the most commonly reported.

CLINICAL SIGNIFICANCE

Cyclophosphamide and prednisolone were well-tolerated with limited side effects. The response rate observed in this cohort of dogs with chemotherapy-naïve B cell multicentric lymphoma is promising. Further comparative studies are required to confirm the safety and effectiveness of this intervention.

Comparing Public Sentiment Toward COVID-19 Vaccines Across Canadian Cities: Analysis of Comments on Reddit

Background

Social media enables the rapid consumption of news related to COVID-19 and serves as a platform for discussions. Its richness in text-based data in the form of posts and comments allows researchers to identify popular topics and assess public sentiment. Nonetheless, the vast majority of topic extraction and sentiment analysis based on social media is performed on the platform or country level and does not account for local culture and policies.

Objective

The aim of this study is to use location-based subreddits on Reddit to study city-level variations in sentiments toward vaccine-related topics.

Methods

Comments on posts providing regular updates on COVID-19 statistics in the Vancouver (r/vancouver, n=49,291), Toronto (r/toronto, n=20,764), and Calgary (r/calgary, n=21,277) subreddits between July 13, 2020, and June 14, 2021, were extracted. Latent Dirichlet allocation was used to identify frequently discussed topics. Sentiment (joy, sadness, fear, and anger) scores were assigned to comments through random forest regression.

Results

The number of comments on the 250 posts from the Vancouver subreddit positively correlated with the number of new daily COVID-19 cases in British Columbia (R=0.51, 95% CI for slope 0.18-0.29; P<.001). From the comments, 13 topics were identified. Two were related to vaccines, 1 regarding vaccine uptake and the other about vaccine supply. The levels of discussion for both topics were linked to the total number of vaccines administered (Granger test for causality, P<.001). Comments pertaining to either topic displayed higher scores for joy than for other topics (P<.001). Calgary and Toronto also discussed vaccine uptake. Sentiment scores for this topic differed across the 3 cities (P<.001).

Conclusions

Our work demonstrates that data from city-specific subreddits can be used to better understand concerns and sentiments around COVID-19 vaccines at the local level. This can potentially lead to more targeted and publicly acceptable policies based on content on social media.

Séroprévalence SARS-Cov-2 chez les professionnels de santé : étude multicentrique avec analyse des facteurs de risque professionnels et extraprofessionnels

Introduction

L’objectif de notre étude était d’évaluer la séroprévalence SARS-Cov-2 chez les professionnels de santé, après la première vague Covid-19, et d’analyser les facteurs professionnels et extraprofessionnels modifiant cette prévalence.

Matériels et méthodes

Suite aux instructions gouvernementales proposant de réaliser une sérologie Covid-19 à tout professionnel de santé après la première vague, nous avons réalisé une étude transversale, multicentrique. Tous les professionnels volontaires des quatre centres participants étaient invités à réaliser une sérologie et à remplir un questionnaire concernant leurs données démographiques, leurs caractéristiques professionnelles, l’utilisation des équipements de protection individuelle et l’exposition extra professionnelle au Covid-19. Nous avons calculé la prévalence SARS-Cov-2 et utilisé une régression logistique en appliquant un effet centre.

Résultats

Un total de 3454 professionnels ont participé à l’étude dont 83,4 % de femmes. L’âge moyen était de 40,6 ans [31,8–50,3]. En médiane, la prévalence sérologique SARS-Cov-2 était de 5 % (95 % IC, 4,3 %–5,8 %). Les facteurs associés à une plus forte séroprévalence étaient : l’âge < 30 ans (aOR = 1,59, (95 % IC, 1,06–2,37)), le statut d’étudiant (aOR = 3,38, (95 % IC, 1,62–7,05)) avec une séroprévalence de 16,9 % dans cette catégorie. L’unité de travail, y compris le fait d’avoir travaillé en unité Covid ou en réanimation, ainsi que l’exposition à des patients (quel que soit leur statut infectieux) n’étaient pas associé à une augmentation de la séroprévalence. Par contre les professionnels rapportant un contact avec un patient Covid, sans protection adaptée, ou ayant pratiqué des taches aérosolisantes, y compris avec un masque FFP2, avaient un surrisque d’infection Covid-19 (respectivement aOR à 1,66 et 1,7). Enfin, l’exposition à un collègue infecté ou à un cas familial était également associée à une augmentation de la prévalence sérologique.

Conclusion

Les mesures mises en place pour limiter la transmission du SARS-Cov-2 des patients aux professionnels de santé semblent efficaces. En complément de la vaccination, l’éviction systématique des professionnels infectés, la formation des étudiants et le rappel des mesures d’hygiène durant les temps de pause pourraient limiter la contamination des professionnels de santé.

Orthotopic heart transplantation and concomitant aortic arch replacement in an adult Fontan patient with hypoplastic left heart syndrome

Heart failure and neoaortic dilation are common long-term complications in patients with hypoplastic left heart syndrome after single-ventricle palliation. Orthotopic heart transplantation and concomitant transverse aortic arch replacement can be performed safely and effectively. The addition of preoperative three-dimensional modelling can supplement operative planning, facilitate intraoperative execution, and optimize clinical outcomes.

Aortic Valve Neocuspidization In a Pulmonary Autograft

Management of aortic valve (AV) disease in the pediatric population is challenged by a lack of attractive valve replacement options. The Ross procedure has been prominent for these patients, however long-term reports have revealed concerns, namely neo-aortic root dilation and regurgitation. More recently, AV neocuspidization (AVNeo) has emerged as an alternative to the Ross operation or other valve replacement procedures in pediatric patients with congenital AV disease. We report the first successful case of AVNeo of a previously implanted pulmonary autograft.

Simplified heavy-atom derivatization of protein structures via co-crystallization with the MAD tetragon tetrabromoterephthalic acid

The phase problem is a persistent bottleneck that impedes the structure-determination pipeline and must be solved to obtain atomic resolution crystal structures of macromolecules. Although molecular replacement has become the predominant method of solving the phase problem, many scenarios still exist in which experimental phasing is needed. Here, a proof-of-concept study is presented that shows the efficacy of using tetrabromoterephthalic acid (B4C) as an experimental phasing compound. Incorporating B4C into the crystal lattice using co-crystallization, the crystal structure of hen egg-white lysozyme was solved using MAD phasing. The strong anomalous signal generated by its four Br atoms coupled with its compatibility with commonly used crystallization reagents render B4C an effective experimental phasing compound that can be used to overcome the phase problem.

Quantifying Bone Quality Using Computed Tomography Hounsfield Units in the Mid-sagittal View of the Lumbar Spine

BACKGROUND

Computed tomography Hounsfield unit (HU) is an alternative tool to the dual energy x-ray absorptiometry scan T-score to quantify the bone quality. DEXA scan can overestimate the bone mineral density. We studied the correlation of the vertebral mid-axial and mid-sagittal HU to the T-score.

METHODS

We retrospectively reviewed the electronic medical records of patients who underwent dual energy x-ray absorptiometry and computed tomography scans within 1 year. Age, sex, mid-axial and mid-sagittal HU, and T-score were collected and statistically analyzed.

RESULTS

We identified 100 patients with computed tomography of the L1-L4. There were 80 female and 20 male patients. The average age was 60.25 years (±12.54 years). Nineteen patients were diagnosed with degenerative spine disease. There were 56 patients with a normal T-score, 33 with osteopenia, and 11 with osteoporosis. The average HU for the mid-sagittal view was 163 (±59) for L1, 159 (±62) for L2, 151 (±59) for L3, and 150 (±62) for L4. The mid-axial and mid-sagittal HU were positively correlated to the DEXA T-score (P < 0.001). The HU was 177 (95% CI: 160-194) for normal T-scores, 132 (120-143) for T-scores indicating osteopenia, and 106 (88-124) for T-scores indicating osteoporosis (P < 0.001). Post hoc analysis showed no difference between osteopenia and osteoporosis (P = 0.46).

CONCLUSIONS

Mid-sagittal HU is positively correlated to the T-score, similar to the mid-axial HU. Therefore, it can be used to acquire a general overview of the bone quality before spinal instrumentation.

Family dynamics moderate the impact of discrimination on wellbeing for Latino young adults

OBJECTIVES

This study examined family dynamics as a moderator of the association between discrimination and both depression and life satisfaction for Latino youth. Specifically, we hypothesized that discrimination would have a negative impact on depression and life satisfaction. We also hypothesized that negative family dynamics would compound the negative impact of discrimination, whereas positive family dynamics would buffer against the impact of discrimination on depression and life satisfaction.

METHOD

Participants were 229 Latino youth (M_age = 22.40, SD = 2.46, % female = 81.7) from a diverse region who completed measures of perceived discrimination, depressive symptoms, life satisfaction, and family relationship dynamics. Regression models were used to test both direct associations and moderation (i.e., interaction effects) between these variables.

RESULTS

Findings indicated that negative aspects of family dynamics marginally exacerbated the link between discrimination and depression and life satisfaction, and were also directly associated with these outcomes. Family positivity significantly moderated the association between discrimination and both depression and life satisfaction. However, positive aspects of family dynamics were only associated with more positive outcomes when discrimination was minimal to absent.

CONCLUSIONS

Family dynamics moderated the association between discrimination and both depression and life satisfaction in Latino youth. However, family dynamics did not appear sufficient to buffer against the negative impact of discrimination, suggesting that even positive and cohesive families cannot buffer youth from discrimination. Marginal findings suggest that negative family dynamics compound the negative impact of discrimination. Implications for improving the mental health of Latino youth through targeting both discrimination and family dynamics are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Derivatization of Protein Crystals with I3C using Random Microseed Matrix Screening

Protein structure elucidation using X-ray crystallography requires both high quality diffracting crystals and computational solution of the diffraction phase problem. Novel structures that lack a suitable homology model are often derivatized with heavy atoms to provide experimental phase information. The presented protocol efficiently generates derivatized protein crystals by combining random microseeding matrix screening with derivatization with a heavy atom molecule I3C (5-amino-2,4,6-triiodoisophthalic acid). By incorporating I3C into the crystal lattice, the diffraction phase problem can be efficiently solved using single wavelength anomalous dispersion (SAD) phasing. The equilateral triangle arrangement of iodine atoms in I3C allows for rapid validation of a correct anomalous substructure. This protocol will be useful to structural biologists who solve macromolecular structures using crystallography-based techniques with interest in experimental phasing.

Targeting Unconventional Pathways in Pursuit of Novel Antifungals

The impact of invasive fungal infections on human health is a serious, but largely overlooked, public health issue. Commonly affecting the immunocompromised community, fungal infections are predominantly caused by species of Candida, Cryptococcus, and Aspergillus. Treatments are reliant on the aggressive use of pre-existing antifungal drug classes that target the fungal cell wall and membrane. Despite their frequent use, these drugs are subject to unfavorable drug-drug interactions, can cause undesirable side-effects and have compromised efficacy due to the emergence of antifungal resistance. Hence, there is a clear need to develop novel classes of antifungal drugs. A promising approach involves exploiting the metabolic needs of fungi by targeted interruption of essential metabolic pathways. This review highlights potential antifungal targets including enolase, a component of the enolase-plasminogen complex, and enzymes from the mannitol biosynthesis and purine nucleotide biosynthesis pathways. There has been increased interest in the enzymes that comprise these particular pathways and further investigation into their merits as antifungal targets and roles in fungal survival and virulence are warranted. Disruption of these vital processes by targeting unconventional pathways with small molecules or antibodies may serve as a promising approach to discovering novel classes of antifungals.

Vanishing white matter: Eukaryotic initiation factor 2B model and the impact of missense mutations

Background

Vanishing white matter (VWM) is a leukodystrophy, caused by recessive mutations in eukaryotic initiation factor 2B (eIF2B)‐subunit genes (EIF2B1–EIF2B5); 80% are missense mutations. Clinical severity is highly variable, with a strong, unexplained genotype–phenotype correlation.

Materials and Methods

With information from a recent natural history study, we severity‐graded 97 missense mutations. Using in silico modeling, we created a new human eIF2B model structure, onto which we mapped the missense mutations. Mutated residues were assessed for location in subunits, eIF2B complex, and functional domains, and for information on biochemical activity.

Results

Over 50% of mutations have (ultra‐)severe phenotypic effects. About 60% affect the ε‐subunit, containing the catalytic domain, mostly with (ultra‐)severe effects. About 55% affect subunit cores, with variable clinical severity. About 36% affect subunit interfaces, mostly with severe effects. Very few mutations occur on the external eIf2B surface, perhaps because they have minor functional effects and are tolerated. One external surface mutation affects eIF2B‐substrate interaction and is associated with ultra‐severe phenotype.

Conclusion

Mutations that lead to (ultra‐)severe disease mostly affect amino acids with pivotal roles in complex formation and function of eIF2B. Therapies for VWM are emerging and reliable mutation‐based phenotype prediction is required for propensity score matching for trials and in the future for individualized therapy decisions.

Persistence of Late Gadolinium Enhancement on Follow-Up CMR Imaging in Children with Acute Myocarditis

Cardiac magnetic resonance (CMR) imaging is the gold standard non-invasive test for the diagnosis of acute myocarditis. Late gadolinium enhancement (LGE) on CMR imaging signifies myocardial fibrosis or scar but information on long-term follow-up in pediatric patients is limited. The aim of this study is to evaluate the persistence of LGE in follow-up CMR imaging and highlight the need for serially following LGE after acute myocarditis in children. A retrospective review of the CMR images in pediatric patients less than 18 years of age at Children's Memorial Hermann Hospital was performed from October 31, 2010, to December 31, 2017. The ages of the patients included in the study ranged from 10 to 17 years. Out of 34 subjects, 12 subjects had a follow-up CMR imaging after the initial CMR imaging. Cardiac enzymes and inflammatory markers were elevated in all patients on initial presentation with normalization seen for all patients on follow-up testing. Baseline CMR imaging demonstrated depressed function in 50% of patients (6/12) with recovery of biventricular function seen in all except for one patient. LGE was detected in 10 out of 12 patients on baseline CMR and persisted in all on follow--up CMR imaging. Two patients did not have LGE at baseline CMR and had no evidence of LGE at follow-up CMR. Despite resolution of acute myocardial inflammation, LGE persisted in all of our study subjects. There is neither an agreement on time interval to perform follow-up CMR, nor on duration of follow-up. We recommend large-scale prospective CMR study for long-term follow-up evaluation of children after acute myocarditis.

Nucleoside selectivity of Aspergillus fumigatus nucleoside-diphosphate kinase

Aspergillus fumigatus infections are rising at a disconcerting rate in tandem with antifungal resistance rates. Efforts to develop novel antifungals have been hindered by the limited knowledge of fundamental biological and structural mechanisms of A. fumigatus propagation. Biosynthesis of NTPs, the building blocks of DNA and RNA, is catalysed by NDK. An essential enzyme in A. fumigatus, NDK poses as an attractive target for novel antifungals. NDK exhibits broad substrate specificity across species, using both purines and pyrimidines, but the selectivity of such nucleosides in A. fumigatus NDK is unknown, impeding structure-guided inhibitor design. Structures of NDK in unbound- and NDP-bound states were solved, and NDK activity was assessed in the presence of various NTP substrates. We present the first instance of a unique substrate binding mode adopted by CDP and TDP specific to A. fumigatus NDK that illuminates the structural determinants of selectivity. Analysis of the oligomeric state reveals that A. fumigatus NDK adopts a hexameric assembly in both unbound- and NDP-bound states, contrary to previous reports suggesting it is tetrameric. Kinetic analysis revealed that ATP exhibited the greatest turnover rate (321 ± 33.0 s^-1 ), specificity constant (626 ± 110.0 mm^-1 ·s^-1 ) and binding free energy change (-37.0 ± 3.5 kcal·mol^-1 ). Comparatively, cytidine nucleosides displayed the slowest turnover rate (53.1 ± 3.7 s^-1 ) and lowest specificity constant (40.2 ± 4.4 mm^-1 ·s^-1 ). We conclude that NDK exhibits nucleoside selectivity whereby adenine nucleosides are used preferentially compared to cytidine nucleosides, and these insights can be exploited to guide drug design. ENZYMES: Nucleoside-diphosphate kinase (EC 2.7.4.6). DATABASE: Structural data are available in the PDB database under the accession numbers: Unbound-NDK (6XP4), ADP-NDK (6XP7), GDP-NDK (6XPS), IDP-NDK (6XPU), UDP-NDK (6XPT), CDP-NDK (6XPW), TDP-NDK (6XPV).