Reaction thermodynamics as a constraint on piscine steroidogenesis flux distributions

While a considerable amount is known of the dynamics of piscine steroidogenesis during reproduction, the influence of thermodynamics constraints on its control has not been studied. In this manuscript, Gibbs free energy change of reactions was calculated for piscine steroidogenesis using the in silico eQuilibrator thermodynamics calculator. The analysis identified cytochrome P450 (cyp450) oxidoreductase reactions to have more negative Gibbs free energy changes relative to hydroxysteroid (HSD) and transferase reactions. In addition, a more favorable Gibbs free energy change was predicted for the Δ5 (cyp450 catalyzed) vs. Δ4 (HSD catalyzed) steroidogenesis branch-point, which converts pregnenolone to 17α-hydroxypregnenolone or progesterone respectively. Comparison of in silico predictions with in vivo experimentally measured flux across the Δ5 vs. Δ4 branch-point showed higher flux through the thermodynamically more favorable Δ5 pathway in reproducing or spawning vs. non-spawning fathead minnows (Pimephales promelas). However, the exposure of fish to endocrine stressors such as hypoxia or the synthetic estrogen 17α-ethinylestradiol (EE2), resulted in increased flux through both Δ5 and Δ4 pathways, indicating an adaptive response to increase steroidogenic redundancy. The correspondence of elevated flux through the Δ5 branch-point in spawning fish indicated the use of a thermodynamically favorable pathway to optimize steroid hormone productions during reproduction. We hypothesize that such selective use of a thermodynamically favorable steroidogenesis pathway may conserve reduced equivalents or transcriptional costs for investment to other biosynthetic or catabolic reactions to support reproduction. If generalizable, such an approach can provide novel insights into the structural principles and regulation of steroidogenesis or other metabolic pathways.

Use of Next-Generation Sequencing in a State-Wide Strategy of HIV-1 Surveillance: Impact of the SARS-COV-2 Pandemic on HIV-1 Diagnosis and Transmission

BACKGROUND

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic posed an unpreceded threat to the management of other pandemics such as human immunodeficiency virus-1 (HIV-1) in the United States. The full impact of the SARS-CoV-2 pandemic on the HIV-1 pandemic needs to be evaluated.

METHODS

All individuals with newly reported HIV-1 diagnoses from NC State Laboratory of Public Health were enrolled in this prospective observational study, 2018-2021. We used a sequencing-based recency assay to identify recent HIV-1 infections and to determine the days postinfection (DPI) for each person at the time of diagnosis.

RESULTS

Sequencing used diagnostic serum samples from 814 individuals with new HIV-1 diagnoses spanning this 4-year period. Characteristics of individuals diagnosed in 2020 differed from those in other years. People of color diagnosed in 2021 were on average 6 months delayed in their diagnosis compared to those diagnosed in 2020. There was a trend that genetic networks were more known for individuals diagnosed in 2021. We observed no major integrase resistance mutations over the course of the study.

CONCLUSIONS

SARS-CoV-2 pandemic may contribute to the spread of HIV-1. Public health resources need to focus on restoring HIV-1 testing and interrupting active, ongoing, transmission.

A systematic review and meta-analysis of the clinimetric properties of the core outcome measurement instruments for clinical effectiveness trials of nutritional and metabolic interventions in critical illness (CONCISE)

BACKGROUND

CONCISE is an internationally agreed minimum set of outcomes for use in nutritional and metabolic clinical research in critically ill adults. Clinicians and researchers need to be aware of the clinimetric properties of these instruments and understand any limitations to ensure valid and reliable research. This systematic review and meta-analysis were undertaken to evaluate the clinimetric properties of the measurement instruments identified in CONCISE.

METHODS

Four electronic databases were searched from inception to December 2022 (MEDLINE via Ovid, EMBASE via Ovid, CINAHL via Healthcare Databases Advanced Search, CENTRAL via Cochrane). Studies were included if they examined at least one clinimetric property of a CONCISE measurement instrument or recognised variation in adults ≥ 18 years with critical illness or recovering from critical illness in any language. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist for systematic reviews of Patient-Reported Outcome Measures was used. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were used in line with COSMIN guidance. The COSMIN checklist was used to evaluate the risk of bias and the quality of clinimetric properties. Overall certainty of the evidence was rated using a modified Grading of Recommendations, Assessment, Development and Evaluation approach. Narrative synthesis was performed and where possible, meta-analysis was conducted.

RESULTS

A total of 4316 studies were screened. Forty-seven were included in the review, reporting data for 12308 participants. The Short Form-36 Questionnaire (Physical Component Score and Physical Functioning), sit-to-stand test, 6-m walk test and Barthel Index had the strongest clinimetric properties and certainty of evidence. The Short Physical Performance Battery, Katz Index and handgrip strength had less favourable results. There was limited data for Lawson Instrumental Activities of Daily Living and the Global Leadership Initiative on Malnutrition criteria. The risk of bias ranged from inadequate to very good. The certainty of the evidence ranged from very low to high.

CONCLUSIONS

Variable evidence exists to support the clinimetric properties of the CONCISE measurement instruments. We suggest using this review alongside CONCISE to guide outcome selection for future trials of nutrition and metabolic interventions in critical illness.

TRIAL REGISTRATION

PROSPERO (CRD42023438187). Registered 21/06/2023.

Social determinants among Black people during pregnancy following a short interpregnancy interval

BACKGROUND

Short interpregnancy interval has been shown to be a key contributor to infant mortality. Black pregnant people have a higher incidence of short interpregnancy interval than people of other races and ethnicities, as well as higher rates of infant mortality. Understanding the factors related to racial disparities in short interpregnancy interval and infant mortality are a public health priority.

OBJECTIVE

This study aimed to examine the relationship between social determinants of health and interpregnancy interval in Black pregnant people by comparing those with a short interpregnancy interval defined as <18 months with those with a referent interpregnancy interval defined as ≥18 months.

STUDY DESIGN

This was a nested case-control study from a prospective cohort analyzing social determinants of health in 576 postpartum patients at an urban medical center, 2011-2021. Sociodemographic, pregnancy, and maternal characteristic data were collected from participants' medical records. Structured interviews measured participants' health behaviors, physical environment, social support, health literacy, and structural drivers. Differences in social determinants of health among Black study participants were compared between those with a short interpregnancy interval (<18 months) and those with a referent interpregnancy interval (≥18 months). The odds ratios were calculated to assess the association between short interpregnancy interval and social determinants. Factors with significant differences between the short interpregnancy interval and referent interpregnancy interval groups in Black participants were compared with that of White groups for social context.

RESULTS

Black participants with a short interpregnancy interval were more likely to report financial support from the Special Supplemental Nutrition Program for Women, Infants, and Children (odds ratio, 2.4; 95% confidence interval, 1.2-5.1), negative feelings toward the pregnancy (odds ratio, 2.4; 95% confidence interval, 1.2-4.9), choosing not to breastfeed because they do not like it (odds ratio ,12.0; 95% confidence interval, 1.5-543.1), not receiving prenatal care as early as desired (odds ratio, 3.4; 95% confidence interval, 1.6-7.2) because of consid- eration of pregnancy termination (odds ratio, 5.2; 95% confidence interval, 1.2-30.5) and less likely to report low levels of social support (odds ratio, 0.3; 95% confidence interval, 0.1-0.8) than Black participants with a referent interpregnancy interval.

CONCLUSION

Social determinants of health that differed between participants with a short interpregnancy interval and those with a referent interpregnancy interval were Special Supplemental Nutrition Program for Women, Infants, and Children support, feelings toward the pregnancy, social support, breastfeeding intent, and delayed prenatal care because of consideration of abortion. Previous studies examining infant mortality risk factors used White people as the referent group when analyzing social determinants. Our study focused specifically on understanding the lives of Black pregnant people so that future public health initiatives focused on social determinants may attenuate the racial disparity of infant mortality in the United States.

Influence of the COVID-19 pandemic on social determinants of health among an inner-city obstetrical population

BACKGROUND

Social determinants of health are a well-described influencer of pregnancy-related morbidity and mortality. It is unclear how societal changes secondary to the COVID-19 pandemic altered the social determinants of health among pregnant patients.

OBJECTIVE

This study aimed to investigate differences in the social determinants of health among patients who experienced pregnancy before and during the COVID-19 pandemic.

STUDY DESIGN

This was a secondary analysis of an ongoing prospective cohort study examining the social determinants of health in postpartum patients at a single inner-city academic medical center. The planned secondary analysis was to compare the social determinants of health between patients that experienced societal changes before the pandemic and patients that experienced societal changes during the pandemic. Patients were included in the pandemic group if they delivered on or after March 30, 2020; moreover, patients in the pandemic group were compared with those who delivered before March 30, 2020 (referent group). Medical records were used to collect sociodemographic, pregnancy, and infant outcome data. The study participants were interviewed to collect detailed information regarding their perceived social, emotional, and physical environment as indicators of social determinants of health. Generalized linear modeling estimated the influence of social determinants of health  on births during the COVID-19 pandemic.

RESULTS

Overall, 577 patients were enrolled in the study, of which 452 (78%) delivered before the COVID-19 pandemic and 125 (22%) delivered during the pandemic. Patients who delivered during the pandemic were more likely to report limited social or emotional support (relative risk, 1.62; 95% confidence interval, 1.02-2.59) and higher race-based discrimination (relative risk, 1.59; 95% confidence interval, 1.00-2.53). Mothers in the prepandemic group were more likely to have used federally funded programs, such as Medicaid, food stamps, and the Special Supplemental Nutrition Program for Women, Infants, and Children, during their pregnancy. Furthermore, the referent group reported more limited access to transportation. In addition, mothers in the prepandemic group were more likely to initiate prenatal care at a later gestational age and have fewer total prenatal care visits.

CONCLUSION

The COVID-19 pandemic created unprecedented changes in pregnancy care, and these were reflected in social determinants of health. It is imperative that we focus on the social determinants of health that were mitigated during this time and their effects on maternal and infant health.

Challenges in diagnosis and biomarker testing for RET-altered lung and thyroid cancer care: an international mixed-method study

BACKGROUND

The introduction of new targeted therapies for RET-altered lung and thyroid cancers (LC/TC) has impacted pathologists' practice by making genomic testing more relevant. Variations in health systems and treatment access result in distinct clinical challenges and barriers. This study aimed to assess practice gaps and challenges experienced by pathologists involved in the diagnosis of RET-altered LC/TC, including biomarker testing, to inform educational solutions.

METHODS

Pathologists in Germany, Japan, the UK, and US participated in this ethics-approved mixed-methods study, which included interviews and surveys (data collected January-March 2020). Qualitative data was thematically analysed, quantitative data was analysed with chi-square and Kruskal-Wallis H-tests, and both were triangulated.

RESULTS

A total of 107 pathologists took part in this study. Knowledge gaps were reported regarding genomic testing for LC/TC in Japan (79/60%), the UK (73/66%), and the US (53/30%). Skill gaps were reported when selecting genomic biomarker tests to diagnose TC in Japan (79%), the UK (73%) and US (57%) and when performing specific biomarker tests, especially in Japan (82% for RET) and in the UK (75% for RET). Japanese participants (80%) reported uncertainty about what information to share with the multidisciplinary team to ensure optimal patient-centered care. At the time of data collection, pathologists in Japan faced access barriers to using RET biomarker tests: only 28% agreed that there are relevant RET genomic biomarker tests available in Japan, versus 67% to 90% in other countries.

CONCLUSIONS

This study identified areas where pathologists need additional continuing professional development opportunities to enhance their competencies and better support delivery of care to patients with RET-altered lung or thyroid tumours. Addressing identified gaps and improving competencies of pathologists in this field should be emphasised in continuing medical education curricula and through quality improvement initiatives. Strategies deployed on an institutional and health system level should aim to improve interprofessional communication and genetic biomarker testing expertise.

Mechanical and Biocompatibility Properties of 3D-Printed Dental Resin Reinforced with Glass Silica and Zirconia Nanoparticles: In Vitro Study

This study aimed to assess the mechanical and biocompatibility properties of dental resin reinforced with different nanoparticle additives. Temporary crown specimens were 3D-printed and grouped based on nanoparticle type and amount, including zirconia and glass silica. Flexural strength testing evaluated the material's ability to withstand mechanical stress using a three-point bending test. Biocompatibility was tested using MTT and dead/live cell assays to assess effects on cell viability and tissue integration. Fractured specimens were analysed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) for fracture surface examination and elemental composition determination. Results show that adding 5% glass fillers and 10-20% zirconia nanoparticles significantly improves the flexural strength and biocompatibility of the resin material. Specifically, the addition of 10%, 20% zirconia, and 5% glass silica by weight significantly increases the flexural strength of the 3D-printed resins. Biocompatibility testing reveals cell viabilities greater than 80% in all tested groups. Reinforced 3D-printed resin holds clinical potential for restorative dentistry, as zirconia and glass fillers have been shown to enhance mechanical and biocompatibility properties of dental resin, making it a promising option for dental restorations. The findings of this study may contribute to the development of more effective and durable dental materials.

A285 CHANGE IN ALT DURING MODIFIED OPTIFAST WEIGHT LOSS PROGRAM IN INDIVIDUALS AT RISK FOR NON-ALCOHOLIC FATTY LIVER DISEASE

Background

Obesity is linked to various health complications, including diabetes, metabolic syndrome, cardiovascular disease, and non-alcoholic fatty liver disease (NAFLD). NAFLD is the most frequent cause of abnormally high alanine aminotransferase (ALT) levels. ALT is released at higher levels during hepatocellular injury and represents a simple, low cost and non-invasive method of assessing liver damage. There are conflicting data on ALT response to weight loss between men and women, with some evidence of transient increase in ALT levels in women.

Purpose

The aim of this study was to assess the impact of a dietary weight loss intervention with Optifast on ALT in patients with obesity who have baseline elevated ALT levels.

Method

This was a retrospective cohort study of Ontario adults who participated in a 26 week weight loss program, including 6 or 12 weeks of low-calorie liquid diet meal replacement with Optifast 900^® (Nestlé, Canada), between 1992 and 2015. We included patients with elevated baseline ALT levels, defined by > 40 U/L, who had at least one follow-up ALT between week 15 and 26. We excluded patients with nonadherence to dietary intervention, established liver disease or using hepatotoxic drugs, excessive alcohol intake (>11U/wk for females and >14U/wk for males), and insufficient data to calculate FIB-4. The primary outcome was change in ALT levels, measured by normalization (post-intervention ALT < 40 U/L), percentage decrease and absolute decrease. Multiple linear regressions were obtained for the relationship between ALT changes and age, sex, body mass index (BMI) and FIB-4. All analyses were conducted in SPSS. P value of ≤0.05 was considered statistically significant.

Result(s)

444 patients met study criteria. Mean age was 47.1 years +/- 10.9, 49 % of patients were female, and mean BMI was 43.5 kg/m² +/- 7.9. All patients lost weight, with mean weight loss 27.3 kg +/- 11.5 and a mean 20.7% decrease from baseline weight. Mean ALT at baseline was 58.9 U/L +/- 25.4 and mean ALT post intervention was 32.3 U/L +/- 28.1 (p <0.01). 85.1% of patients had normalization of ALT. Mean % decrease in ALT was 41.9% and mean absolute decrease in ALT was 26.6 U/L +/- 25.4. Younger age and higher baseline FIB-4 were significantly associated with a larger decrease in ALT levels, while sex and initial BMI were not significantly associated with changes in ALT.

Conclusion(s)

In patients with obesity and baseline elevated ALT, dietary weight loss intervention with Optifast leads to ALT normalization in most patients, regardless of sex. Younger age at baseline and higher baseline FIB-4 are significantly associated with greater decrease in ALT.

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Disclosure of Interest

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A166 RISK STRATIFICATION OF EARLY RE-HOSPITALIZATION IN PERSONS WITH INFLAMMATORY BOWEL DISEASES USING MULTIVARIABLE MODELS

Background

Hospitalization for persons with inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is a significant contributor to morbidity and health care costs in Canada. Recognition of individuals at high risk of re-hospitalization could help inform targeted outpatient interventions that mitigate this risk.

Purpose

The aim of our study is to derive prediction models of risk of early (90-day) re-hospitalization among persons with IBD.

Method

We conducted a retrospective cohort study of all adult persons with IBD admitted to The Ottawa Hospital, Canada, for an acute IBD-related indication between April 2009 - March 2016. Demographic, clinical, and health services variables were obtained through chart review. Persons were linked to population-based health administrative datasets to identify historical and future IBD-related hospitalizations across the greater Ottawa region. Multivariable logistic regression models of 90-day re-hospitalization in persons with CD and UC were derived, and candidate predictors that demonstrated an independent association with the outcome at a p-value of 0.1 were retained. Bootstrap internal validation (200 iterations) was performed on the final models. Model performance and calibration were evaluated using the optimism-corrected c-statistic value and Hosmer-Lemeshow goodness of fit test, respectively. Adjusted odds ratios are reported with 95% confidence intervals (CI). Optimal probability cut points for re-hospitalization were selected to optimize sensitivity, specificity, and the J (Youden’s) index.

Result(s)

There were 524 CD and 248 UC hospitalizations during the study period. Of these, 57 (10.9%) CD and 27 (10.9%) UC hospitalizations were associated with re-hospitalization within 90 days of discharge. Forty-two candidate predictors were tested among CD hospitalizations, and 35 were tested among UC hospitalizations. Four variables were retained in each of the final models. Model performance and calibration for each variable are described in Table 1. The optimal range of probability cut points allowed for a sensitivity/positive predictive value (PPV)/false positive rate (FPR) of 0.72/0.23/0.29 (maximum J-index of 0.43) in the model for CD, and 0.78/0.33/0.19 (maximum J-index of 0.59) in the model for UC, respectively.

Image

Conclusion(s)

Demographic, clinical, and health services variables at the time of discharge have the potential to help identify persons with IBD at risk of early re-hospitalization, thereby permitting targeted outpatient intervention. Application of the models to our reference cohorts would earmark 1/3 or less of patients for early post-discharge intervention, with the potential to benefit more than 70% of patients destined for early re-hospitalization. Although the PPVs of our models were low, the models incorrectly predicted early re-hospitalization in less than 30% of patients. We are in process of externally validating these models in other jurisdictions across Ontario to test their generalizability.

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Disclosure of Interest

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Coding long COVID: characterizing a new disease through an ICD-10 lens

BACKGROUND

Naming a newly discovered disease is a difficult process; in the context of the COVID-19 pandemic and the existence of post-acute sequelae of SARS-CoV-2 infection (PASC), which includes long COVID, it has proven especially challenging. Disease definitions and assignment of a diagnosis code are often asynchronous and iterative. The clinical definition and our understanding of the underlying mechanisms of long COVID are still in flux, and the deployment of an ICD-10-CM code for long COVID in the USA took nearly 2 years after patients had begun to describe their condition. Here, we leverage the largest publicly available HIPAA-limited dataset about patients with COVID-19 in the US to examine the heterogeneity of adoption and use of U09.9, the ICD-10-CM code for "Post COVID-19 condition, unspecified."

METHODS

We undertook a number of analyses to characterize the N3C population with a U09.9 diagnosis code (n = 33,782), including assessing person-level demographics and a number of area-level social determinants of health; diagnoses commonly co-occurring with U09.9, clustered using the Louvain algorithm; and quantifying medications and procedures recorded within 60 days of U09.9 diagnosis. We stratified all analyses by age group in order to discern differing patterns of care across the lifespan.

RESULTS

We established the diagnoses most commonly co-occurring with U09.9 and algorithmically clustered them into four major categories: cardiopulmonary, neurological, gastrointestinal, and comorbid conditions. Importantly, we discovered that the population of patients diagnosed with U09.9 is demographically skewed toward female, White, non-Hispanic individuals, as well as individuals living in areas with low poverty and low unemployment. Our results also include a characterization of common procedures and medications associated with U09.9-coded patients.

CONCLUSIONS

This work offers insight into potential subtypes and current practice patterns around long COVID and speaks to the existence of disparities in the diagnosis of patients with long COVID. This latter finding in particular requires further research and urgent remediation.

Food Insecurity in an Urban Pregnancy Cohort

OBJECTIVE

Food insecurity is a prominent problem and has been implicated in adverse maternal and neonatal outcomes. This study aims to describe the food insecure population in an urban academic health center perinatal cohort.

STUDY DESIGN

We enrolled 451 postpartum inpatients at the University of Cincinnati Medical Center who completed a questionnaire and were then categorized as food insecure based on U.S. Department of Agriculture standardized survey questions. Generalized linear models estimated the relative influence of maternal characteristics on food insecurity.

RESULTS

Among the study population (n = 426), 18.6% (95% confidence interval: 15.2-22.4%) were classified as food insecure. Factors with increased adjusted relative risk on food insecurity include annual household income <$40,000, obesity, and smoking. Food insecure women also reported lower levels of love, satisfaction, and joy, and higher levels of despair.

CONCLUSION

We recommend the use of a validated screening tool on all pregnant women with the associated psychosocial stressors and social determinants of health.

KEY POINTS

· Food insecurity is prevalent among pregnant women.. · Nearly one in five women (18.6%) in the study cohort were classified as food insecure.. · Food insecure pregnant women were more likely to have additional risks for adverse health outcomes..

School and learning contexts during the COVID-19 pandemic: Implications for child and youth mental health

Despite significant disruption to school during the COVID-19 pandemic, research on the impact on children is sparse. This study examines in-person and virtual learning contexts and the impact of school format on mental health (MH). Children and adolescents were recruited from community and clinical settings. Parents and children completed prospective online surveys about school experiences (November 2020) and MH symptoms (February/March 2021), including school format and activities. Standardized measures of depression, anxiety, inattention, and hyperactivity were collected. Hierarchical regression analyses tested associations between school format and MH. Children (N = 1011; aged 6-18 years) attending school in-person (n = 549) engaged in high levels of participation in COVID-19 health measures and low levels of social learning activities. Learning online in high school was associated with greater MH symptoms (B = -2.22, CI[-4.32,-.12] to B = -8.18, CI[-15.59,-.77]). Children with no previous MH condition that attended school virtually experienced a similar magnitude of MH symptoms as those with previous MH conditions. However, children who attended school in a hybrid in-person format, with no previous MH condition, experienced less hyperactivity as same-age peers with prior MH problems (B = -8.08, CI[1.58,14.58]). Children's learning environments looked very different compared to before the pandemic. Removing children from school environments and limiting opportunities that support their MH, such as social learning activities, is problematic. Efforts to address the learning contexts to protect the mental health of children are needed.

A Novel Cartesian Plot Analysis for Fixed Monolayers That Relates Cell Phenotype to Transfer of Contents between Fibroblasts and Cancer Cells by Cell-Projection Pumping

We recently described cell-projection pumping as a mechanism transferring cytoplasm between cells. The uptake of fibroblast cytoplasm by co-cultured SAOS-2 osteosarcoma cells changes SAOS-2 morphology and increases cell migration and proliferation, as seen by single-cell tracking and in FACS separated SAOS-2 from co-cultures. Morphological changes in SAOS-2 seen by single cell tracking are consistent with previous observations in fixed monolayers of SAOS-2 co-cultures. Notably, earlier studies with fixed co-cultures were limited by the absence of a quantitative method for identifying sub-populations of co-cultured cells, or for quantitating transfer relative to control populations of SAOS-2 or fibroblasts cultured alone. We now overcome that limitation by a novel Cartesian plot analysis that identifies individual co-cultured cells as belonging to one of five distinct cell populations, and also gives numerical measure of similarity to control cell populations. We verified the utility of the method by first confirming the previously established relationship between SAOS-2 morphology and uptake of fibroblast contents, and also demonstrated similar effects in other cancer cell lines including from melanomas, and cancers of the ovary and colon. The method was extended to examine global DNA methylation, and while there was no clear effect on SAOS-2 DNA methylation, co-cultured fibroblasts had greatly reduced DNA methylation, similar to cancer associated fibroblasts.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Cell-Projection Pumping of Fibroblast Contents into Osteosarcoma SAOS-2 Cells Correlates with Increased SAOS-2 Proliferation and Migration, as well as Altered Morphology

We earlier reported that cell-projection pumping transfers fibroblast contents to cancer cells and this alters the cancer cell phenotype. Here, we report on single-cell tracking of time lapse recordings from co-cultured fluorescent fibroblasts and SAOS-2 osteosarcoma cells, tracking 5201 cells across 7 experiments. The fluorescent lipophilic marker DiD was used to label fibroblast organelles and to trace the transfer of fibroblast cytoplasm into SAOS-2 cells. We related SAOS-2 phenotypic change to levels of fluorescence transfer from fibroblasts to SAOS-2 cells, as well as what we term 'compensated fluorescence', that numerically projects mother cell fluorescence post-mitosis into daughter cells. The comparison of absolute with compensated fluorescence allowed us to deduct if the phenotypic effects in mother SAOS-2 cells were inherited by their daughters. SAOS-2 receipt of fibroblast fluorescence correlated by Kendall's tau with cell-profile area and without evidence of persistence in daughter cells (median tau = 0.51, p < 0.016); negatively and weakly with cell circularity and with evidence of persistence (median tau = -0.19, p < 0.05); and very weakly with cell migration velocity and without evidence of persistence (median tau = 0.01, p < 0.016). In addition, mitotic SAOS-2 cells had higher rates of prior fluorescence uptake (median = 64.9 units/day) than non-dividing cells (median = 35.6 units/day, p < 0.016) and there was no evidence of persistence post-mitosis. We conclude that there was an appreciable impact of cell-projection pumping on cancer cell phenotype relevant to cancer histopathological diagnosis, clinical spread and growth, with most effects being 'reset' by cancer cell mitosis.

LB6. Asymptomatic Infection and Duration of Viral Shedding in Symptomatic Breakthrough Infections in a Phase 3 Study of AZD1222 (ChAdOx1 nCoV-19)

Background

SARS-CoV-2 vaccine efficacy (VE) against asymptomatic infection and impact on viral shedding during breakthrough infections have critical implications for pandemic control. AZD1222 (ChAdOx1 nCoV-19; 2 doses, 4 weeks apart) demonstrated VE of 74.0% (95% CI 65.3, 80.5) against the primary endpoint of symptomatic RT-PCR-confirmed COVID-19 and safety in a Phase 3, 2:1 randomized, placebo-controlled study in the US, Chile and Peru (n=32,451). Here we present exploratory analyses on asymptomatic infections determined by nucleocapsid (N) seroconversion and time to viral clearance in participants with symptomatic infections determined by N seroconversion (primary data cut, March 5, 2021).

Methods

N seroconversion was assessed at all scheduled and illness visits in the fully vaccinated analysis set (Table). In this analysis, symptomatic infections are defined as N seroconversion ≥ 15 days post second dose in participants who attended an illness visit with ≥ 1 qualifying COVID-19 symptom and had ≥ 1 positive RT-PCR result for SARS-CoV-2. Asymptomatic infections are defined as N seroconversion ≥ 15 days post second dose in participants who did not meet the criteria for symptomatic infections. In participants with symptomatic infections, viral shedding in saliva was assessed for 28 days and cumulative incidence of viral clearance was determined.

Table. AZD1222 VE against symptomatic and potentially asymptomatic SARS-CoV-2 infections as determined by N seroconversion

Results

Overall, 358 participants had SARS-CoV-2 infections as determined by N seroconversion (Table). Incidences per 1000 person-years of symptomatic infections were 25.62 for AZD1222 vs 103.42 for placebo (VE 75.23%; 95% CI 65.33, 82.31) and of asymptomatic infections were 51.24 vs 111.95 (VE 54.24%; 95% CI 39.99, 65.10) (Table). Sensitivity analyses for N seroconversion using the primary endpoint and CDC criteria for defining symptomatic/asymptomatic status were supportive. Median time to viral clearance in saliva in participants with symptomatic infections was 11 days (AZD1222, n=52) vs 16 days (placebo, n=92) (Figure).

Figure. Viral clearance in saliva samples in participants with symptomatic infections as determined by N seroconversion

Conclusion

AZD1222 resulted in lower yet meaningful VE against asymptomatic compared to symptomatic infections, as determined by N seroconversion, and shortened viral shedding in symptomatic SARS-CoV-2 breakthrough infections vs placebo, highlighting its potential contribution to reducing viral transmission.

Funding Statement

Disclosures

Ann R. Falsey, MD, AstraZeneca (Individual(s) Involved: Self): Grant/Research Support; BioFire Diagnostics (Individual(s) Involved: Self): Grant/Research Support; Janssen (Individual(s) Involved: Self): Grant/Research Support; Merck, Sharpe and Dohme (Individual(s) Involved: Self): Grant/Research Support; Novavax (Individual(s) Involved: Self): Other Financial or Material Support, Paid DSMB member; Pfizer (Individual(s) Involved: Self): Grant/Research Support Merlin L. Robb, M.D., Henry M. Jackson Foundation (Other Financial or Material Support, This work was conducted under a funding agreement with the USG through an INteragency Personnel Agreement) Hong-Van Tieu, M.D, M.S., National Institutes of Health (Grant/Research Support) Lawrence Corey, MD, NIH (Grant/Research Support) Kathleen Neuzil, MD, MPH, NIH (Grant/Research Support, Other Financial or Material Support, Dr. Neuzil is the CoVPN co-chair with testing of COVID-19 vaccines with salary support from NIH.)Pfizer (Grant/Research Support) Jill Maaske, M.D., AstraZeneca (Employee, Shareholder) Brett Jepson, n/a, AstraZeneca (Other Financial or Material Support, On assignment to AstraZeneca)Cytel, Inc. (Employee) Stephanie Sproule, n/a, AstraZeneca (Other Financial or Material Support, Fees for statistical consulting.) Elizabeth Kelly, n/a, AstraZeneca (Employee, Shareholder)

Outcomes of free flap reconstructive surgery in head and neck cancer patients over 80-years old

An increasing elderly population in the United Kingdom has led to an increasing number of older patients with head and neck cancer, resulting in a greater demand for complex head and neck reconstructive surgery in this potentially high-risk age group. A possible perceived poorer tolerance to such major treatment risks under-treating some of these patients. The purpose of this study was to assess the outcomes in the elderly population (older than 80 years) who had undergone free flap reconstruction following head and neck cancer resection. A retrospective review of 127 patients was performed. Eighteen patients were 80 or older (14.2%) and 109 under 80 (85.8%). The elderly group experienced increased number of postoperative medical complications (p=0.01), but the surgical complications were not significantly different in the two groups (p=0.4). The average length of hospital stay was significantly longer in the older group (p=0.01). There was one flap failure during the study period, which belonged to the younger group of patients. Elderly patients undergoing free flap reconstruction experience an increased rate of postoperative medical complications resulting in an increased length of hospital stay. However, good surgical outcomes can still be achieved in this age group, and therefore age alone should not be considered as a primary factor in head and neck cancer management.

Influence of Gestational Weight Gain on the Risk of Preterm Birth for Underweight Women Living in Food Deserts

OBJECTIVE

Preterm birth (PTB) and food insecurity are two of the most significant public health crises in the United States. Effects of being underweight among populations with low food security are not well understood. We assess whether the protective effect of gestational weight gain (GWG) for women with low prepregnancy body mass index (BMI) differs by accessibility to sources of healthy food.

STUDY DESIGN

Population-based retrospective cohort study using Ohio birth records analyzing all live births, 2006 to 2015. Analyses were stratified by maternal BMI (underweight, normal, overweight, and obese), Institute of Medicine (IOM) recommended GWG (under vs. met), and whether the U.S. Department of Agriculture (USDA) classified the residential census tract for each birth as a food desert. Food access data were retrieved from the USDA's 2018 Food Access Research Atlas. Covariates were selected using least absolute shrinkage and selection operator regression. Logistic regression models estimated the risk ratio (RR) of PTB for each group based on under or exceeded recommended GWG (reference = met), adjusting for coexisting risk factors.

RESULTS

Analysis was performed on 1,124,299 births. PTB risk was highest for underweight women below GWG recommendations (no food desert: 21.3%, RR = 2.15, 95% confidence interval [CI]: 1.81-2.57; food desert: 21.0%, RR = 1.46, 95% CI: 0.96-2.21). Underweight women living in food deserts who exceeded GWG recommendations had lower PTB risk than those who met GWG recommendations (13.5 vs. 14.3%, RR = 0.85, 95% CI: 0.51-1.41). Factors other than GWG significantly associated with PTB included in the adjusted analysis include maternal age and race, education, marital status, interpregnancy interval, and presence of prepregnancy diabetes or hypertension.

CONCLUSION

Underweight women who do not meet GWG recommendations are at high risk for PTB. Increasing pregnancy weight gain to a level that exceeds IOM recommendations was not associated with a reduction in PTB risk for underweight women who reside in food deserts compared with women who met GWG recommendations.

KEY POINTS

· Women with low prepregnancy BMI are at high risk of PTB.. · Food insecurity increases the risk of PTB for underweight women.. · Excessive GWG for underweight women in food deserts does not reduce PTB risk..

Challenges in lung cancer multidisciplinary collaboration experienced by specialists in four countries

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Background: The importance and challenges of Multidisciplinary Team (MDT) collaboration in managing lung cancer have been increasingly recognized in an ever more complex therapeutic environment. Data on physicians’ viewpoints regarding MDT collaboration in lung cancer care, collected in a broader study assessing challenges related to lung/thyroid cancer patient management, are presented. Methods: A mixed-methods approach was used to analyze this data, combining qualitative interviews and a quantitative survey. Pulmonologists (PLM), oncologists (ONC) and pathologists (PTH) from Germany (GE), Japan (JP), the United Kingdom (UK) and the United States (US) were recruited. Results: A total of 44 specialists participated in interviews and 377 in a survey. Quantitative data reveal that 53% of pulmonologists in JP and 39% in GE have suboptimal knowledge of the timing of patient referral to an oncologist. Fewer PLM/PTH from JP (43%/47%) report a fully integrated MDT team approach in their clinical setting, compared to those from GE (80%/95%), the UK (96%/82%) and the US (82%/97%). Qualitative data indicate that current MDT team practices are perceived as delaying patient care due to significant inefficiencies (sometimes due to lack of knowledge/skills) and unclear responsibilities within the team. Around half of ONC in each country and 78% of PLM from the UK report a gap in knowledge and relevance of each genetic biomarker test according to clinical presentation. PTH in the UK (70%), the US (50%), and JP (72%) report sub-optimal skills identifying biomarker tests to inform the progression of lung cancer (also a challenge for PLM/ONC). Conclusions: This study indicates a need for multi-level interventions addressing systemic and attitudinal barriers as well as knowledge gaps which affect physicians’ ability to collaborate in lung cancer care.

Intersection of Syphilis and HIV Networks to Identify Opportunities to Enhance HIV Prevention

BACKGROUND

HIV and syphilis infection continue at disproportionate rates among minority men who have sex with men (MSM) in the United States. The integration of HIV genetic clustering with partner services can provide important insight into local epidemic trends to guide interventions and control efforts.

METHODS

We evaluated contact networks of index persons defined as minority men and transgender women diagnosed with early syphilis and/or HIV infection between 2018-2020 in two North Carolina regions. HIV clusters were constructed from pol sequences collected through statewide surveillance. A combined "HIV-risk" network, which included persons with any links (genetic or sexual contact) to HIV-positive persons, was evaluated by component size, demographic factors, and HIV viral suppression.

RESULTS

In total, 1,289 index persons were identified and 55% named 1,153 contacts. Most index persons were Black (88%) and young (median age 30 years); 70% had early syphilis and 43% had prevalent HIV infection. Most people with HIV (65%) appeared in an HIV cluster. The combined HIV-risk network (1,590 contact network and 1,500 cluster members) included 287 distinct components; however, 1,586 (51%) were in a single component. Fifty-five percent of network members with HIV had no evidence of viral suppression. Overall, fewer index persons needed to be interviewed to identify one HIV-positive member without viral suppression (1.3 versus 4.0 for contact tracing).

CONCLUSIONS

Integration of HIV clusters and viral loads illuminate networks with high HIV prevalence, indicating recent and ongoing transmission. Interventions intensified towards these networks may efficiently reach persons for HIV prevention and care re-engagement.

Impact of wastewater infrastructure improvements on beach water fecal indicator bacteria levels in Monroe County, Florida

The effects of wastewater infrastructure construction on regional and local environments is unknown. This project evaluated the effects of such projects in Monroe County, Florida, an area that had undergone regional wastewater infrastructure improvements. We used fecal indicator bacteria (FIB) (fecal coliform and enterococci), as a proxy indicator of beach water quality for an 18-year period of record. At the highest level of aggregation, FIBs for all 17 beaches within the county were combined to evaluate trends on a yearly basis. At the lower level, yearly FIB trends were evaluated for each beach separately. FIB data on infrastructure project period (categorical variables: before, during, and after construction), and the influences of environmental conditions (quantitative variables of rainfall and temperature) were also evaluated. In the multiple regression models, enterococci and fecal coliform were significantly associated with rainfall (24 h, p < 0.0001) and water temperature (p < 0.0001) when only the quantitative variables were considered. When both categorical and quantitative variables were considered, project period was significant for enterococci (p < 0.0001) and fecal coliform (p < 0.0001), as was 24 h lagged rainfall. Overall, the most significant factors for both fecal coliform and enterococci were rainfall and project period. Considering all beaches, infrastructure projects seem to have the collective desired effects in the years following construction, as there were decreased FIBs measured at beach sites. Only through the aggregation of all projects and measurements at all beach sites could the decreases in FIB levels be observed. Local analysis is needed to explain anomalies from these general trends for specific beaches. This understanding of FIBs, their responses to environmental and project factors, and the need for aggregated and local site analysis can provide guidance to managers at other locations with similar issues of failing wastewater infrastructure and frequent FIB exceedances.

A100 END-STAGE CIRRHOSIS: EXPLORING THE PERSPECTIVES OF PATIENTS AND THEIR CAREGIVERS

Background

Despite therapy advances for patients with liver disease, readmission rates in patients with decompensated cirrhosis remain high. Studies have evaluated clinical risk factors influencing risk of readmission, but limited data exists on patient related outcome measures. Moreover, scant data exists on the impact of decompensated cirrhosis on caregivers.

Aims

We sought to evaluate and understand the patient experience of hospitalization and post-discharge, including factors perceived to be important by patients and their caregivers.

Methods

We identified patients who were admitted to the Ottawa Hospital for decompensated cirrhosis (October 2018-February 2019). Patients were consented to participate at the time of admission, or at the first clinic appointment with Hepatology post-discharge. Participants were administered a set of validated questionnaires exploring their experiences during their admission, and post-discharge. Questionnaires included the SF-36, Multidimensional Caregiver Strain Index, Social Support Scale, and a sociodemographic sheet. Patients were also asked to identify a caregiver, and if consented, a survey was also administered to their caregiver. Descriptive statistics were performed.

Results

A total of 20 patients and 10 caregivers were captured in the study. Of these, 72% (n=13) self-identified being disabled, retired, or unemployed and not currently looking for work, while 16% (n=3) were working full time. Income wise, 42% (n=8) of patients made between 20–50 thousand dollars, 42% (n=8) made more than fifty thousand, and n=2 had an income less than twenty thousand. With regards to education, 42% (n=8) had some college or technical school training, and 26% (n=5) were college graduates. All patients lived in stable housing, with the majority living alone (n=12, 63%). When assessing health-related quality of life, patients’ general health perception was low (34%), with significant impairment noted in physical role functioning (21%), and vitality (35%). Perceived social support was high, with 78% of patients noting they had a special person they could rely on in need, and someone they could share their feelings with. Our caregiver survey did not reveal any significant burnout trends. Caregivers expressed they were happy to care for their loved one (80%, n=8), and when asked whether they felt resentment or anger towards their spouse or family member, (80%, n=8) said never. Given the exploratory nature and small sample size of the study, we did not run statistical analyses.

Conclusions

Overall, our study revealed that patients with decompensated cirrhosis experience low health-related quality of life, however feel supported by their caregivers. Caregivers did not express significant burnout at first post-discharge visit. Larger studies and longitudinal data would be helpful to better characterize the patient experience in advanced cirrhosis.

Funding Agencies

The Ottawa Hospital Academic Medical Organization (TOHAMO) Quality & Patient Safety Grant

A222 ASSOCIATION BETWEEN PROTON PUMP INHIBITOR USE AND DEVELOPMENT OF HEPATIC ENCEPHALOPATHY AND SPONTANEOUS BACTERIAL PERITONITIS IN HOSPITALIZED PATIENTS WITH CIRRHOSIS

Background

Proton pump inhibitors (PPIs) are commonly prescribed medications which are indicated in various different gastrointestinal (GI) diseases, including peptic ulcer disease, gastroesophageal reflux disorder and upper GI bleeding. There is some evidence to suggest that PPI use in cirrhosis may predispose to the development of hepatic encephalopathy (HE) and spontaneous bacterial peritonitis (SBP), albeit with some controversy.

Aims

We aim to conduct a retrospective epidemiological analysis of the association between PPI use in hospitalized patients with cirrhosis and prevalence of HE and SBP.

Methods

This was a retrospective cohort study of 953 adult patients (mean age 62.3 (SD=12.2)) with cirrhosis admitted to the Ottawa Hospital between January 1, 2011 and December 31, 2015. A chart review was conducted and relevant information extracted.

Results

Average MELD-Na on admission was 17.4 (SD = 7.5) with no significant differences when stratified by in-hospital PPI use (p=0.53). 14.7% of patients had a prior history of HE, 5.4% SBP, 31.6% ascites, 9.3% hepatocellular carcinoma and 1.2% hepatorenal syndrome. 26.4% of patients had a history of varices, of which 34.4% had previous variceal bleeding. 45.4% of patients were on a PPI prior to admission and 69.8% during their hospitalization. Patients with a previous history of HE (16.8% vs. 9.6% p=0.006), varices (31.4% vs. 14.2% p&lt;0.001) and variceal bleed (11.6% vs. 3.1% p&lt;0.001) were more likely to be exposed to a PPI in-hospital. Mortality rate during index admission was 19.4%.

There was no significant association noted between the incidence of HE (31.2% vs. 25.0% p=0.06) or SBP (10.4% vs. 8.0% p=0.25) and in-hospital PPI use. There was also no significant association between PPI use and infectious complications, including bacteremia (8.6% vs. 7.6% p=0.63), pneumonia (12.7% vs. 12.5% p=0.95), urinary tract infections (9.2% vs. 6.6% p=0.19) and clostridium difficile (3.8% vs. 2.1% p=0.18). Patients on a PPI had greater in-hospital mortality (22.0% vs. 13. 5% p=0.002), although there was no significance between cause of death (p=0.31) nor death from infectious complications (18.5% vs. 23.1% p=0.52) between groups. Length of stay (LOS) was longer in patients exposed to PPI (median (IQR) 7 (4–17) vs 6 (3–13) p=0.03). Similar findings were noted on subgroup analysis of decompensated patients.

Conclusions

We did not observe a significant difference in HE, SBP or infectious complications among this cohort of cirrhotic patients by in-hospital PPI use. However, there was a significantly higher mortality rate noted in hospital and longer LOS, despite similar baseline MELD-Na and causes of death. Further study and judicious PPI prescribing practices in this vulnerable population of patients is warranted.

Funding Agencies

None

The polycomb proteins EZH1 and EZH2 co-regulate chromatin accessibility and nephron progenitor cell lifespan in mice

SIX2 (SIX homeobox 2)-positive nephron progenitor cells (NPCs) give rise to all epithelial cell types of the nephron, the filtering unit of the kidney. NPCs have a limited lifespan and are depleted near the time of birth. Epigenetic factors are implicated in the maintenance of organ-restricted progenitors such as NPCs, but the chromatin-based mechanisms are incompletely understood. Here, using a combination of gene targeting, chromatin profiling, and single-cell RNA analysis, we examined the role of the murine histone 3 Lys-27 (H3K27) methyltransferases EZH1 (enhancer of zeste 1) and EZH2 in NPC maintenance. We found that EZH2 expression correlates with NPC growth potential and that EZH2 is the dominant H3K27 methyltransferase in NPCs and epithelial descendants. Surprisingly, NPCs lacking H3K27 trimethylation maintained their progenitor state but cycled slowly, leading to a smaller NPC pool and formation of fewer nephrons. Unlike Ezh2 loss of function, dual inactivation of Ezh1 and Ezh2 triggered overexpression of the transcriptional repressor Hes-related family BHLH transcription factor with YRPW motif 1 (Hey1), down-regulation of Six2, and unscheduled activation of Wnt4-driven differentiation, resulting in early termination of nephrogenesis and severe renal dysgenesis. Double-mutant NPCs also overexpressed the SIX family member Six1 However, in this context, SIX1 failed to maintain NPC stemness. At the chromatin level, EZH1 and EZH2 restricted accessibility to AP-1-binding motifs, and their absence promoted a regulatory landscape akin to differentiated and nonlineage cells. We conclude that EZH2 is required for NPC renewal potential and that tempering of the differentiation program requires cooperation of both EZH1 and EZH2.

Establishing nationally representative benchmarks of farm-gate nitrogen and phosphorus balances and use efficiencies on Irish farms to encourage improvements

Agriculture faces considerable challenges of achieving more sustainable production that minimises nitrogen (N) and phosphorus (P) losses and meets international obligations for water quality and greenhouse gas emissions. This must involve reducing nutrient balance (NB) surpluses and increasing nutrient use efficiencies (NUEs), which could also improve farm profitability (a win-win). To set targets and motivate improvements in Ireland, nationally representative benchmarks were established for different farm categories (sector, soil group and production intensity). Annual farm-gate NBs (kg ha^-1) and NUEs (%) for N and P were calculated for 1446 nationally representative farms from 2008 to 2015 using import and export data collected by the Teagasc National Farm Survey (part of the EU Farm Accountancy Data Network). Benchmarks for each category were established using quantile regression analysis and percentile rankings to identify farms with the lowest NB surplus per production intensity and highest gross margins (€ ha^-1). Within all categories, large ranges in NBs and NUEs between benchmark farms and poorer performers show considerable room for nutrient management improvements. Results show that as agriculture intensifies, nutrient surpluses, use efficiencies and gross margins increase, but benchmark farms minimise surpluses to relatively low levels (i.e. are more sustainable). This is due to, per ha, lower fertiliser and feed imports, greater exports of agricultural products, and for dairy, sheep and suckler cattle, relatively high stocking rates. For the ambitious scenario of all non-benchmark farms reaching the optimal benchmark zone, moderate reductions in farm nutrient surpluses were found with great improvements in profitability, leading to a 31% and 9% decrease in N and P surplus nationally, predominantly from dairy and non-suckler cattle. The study also identifies excessive surpluses for each level of production intensity, which could be used by policy in setting upper limits to improve sustainability.

Tibial rotation outcomes following hamstring lengthening as part of single event multilevel surgery in children with cerebral palsy

BACKGROUND

Hamstring lengthening remains the most common surgical procedure in the treatment of crouch gait for children with cerebral palsy (CP). While sagittal plane knee kinematics have been shown to improve post-surgery, the effects on transverse plane kinematics have not been reported. Given the differing actions of the medial and lateral hamstring muscles there is potential for change in tibial rotation post hamstring lengthening.

RESEARCH QUESTION

What is the effect of medial only versus combined medial and lateral hamstring lengthening on tibial rotation during gait in children with CP?

METHODS

A retrospective analysis of children with a diagnosis of CP who underwent a hamstring lengthening procedure. These children were divided into 2 groups: G1 (n = 18) had isolated medial hamstring lengthening while G2 (n = 30) had combined medial and lateral hamstring lengthening. A matched non-surgical control group (n = 15) was also included. Kinematic data were analysed pre and post-operatively. Pre-operative to post-operative outcomes for G1 and G2, a comparison at baseline for both groups and the difference in outcomes between the groups were analysed. Baseline to follow-up outcomes for the control group were also analysed.

RESULTS

External tibial rotation increased significantly within groups (G1: -10°, p < 0.01; G2: -11°, p < 0.001, control: -7.7, p < 0.01), with no significant difference in the change between the intervention groups. Foot progression angles became more external in both intervention groups (G1: -15°, p < 0.001; G2: -15°, p < 0.0001) and did not change in the control group.

SIGNIFICANCE

Results demonstrated similar increases in external tibial rotation, regardless of whether an isolated medial or combined medial and lateral surgery was performed. The control group demonstrated a similar change in external tibial rotation suggesting that hamstring lengthening surgery does not contribute to increased external tibial rotation in children with CP compared to what would be expected due to natural progression.

Proliferation of microalgae and enterococci in the Lake Okeechobee, St. Lucie, and Loxahatchee watersheds

This study is an analysis of relationships between microalgae (measured as chlorophyll a) and the fecal indicator bacteria enterococci. Microalgae blooms and enterococci exceedances have been occurring in Florida's recreational waterways for years. More recently, this has become a management concern as microalgae blooms have been attributed to potentially toxic cyanobacteria, and enterococci exceedances link to human infection/illness. Since both the microalgal blooms and bacterial exceedances occur in regions that receive managed freshwater releases from Lake Okeechobee, we hypothesized that both the blooms and exceedances are related to excess nutrients from the lake. Two experimental sites, on Lake Okeechobee and the St. Lucie River (downstream of the lake), plus a control site on the Loxahatchee River (which does not receive lake flow) were evaluated. The hypothesis was evaluated through three study components: 1) analysis of available long-term data from local environmental databases, 2) a year-long monthly sampling and analysis of chlorophyll a, enterococci, nutrients, and physical-chemical data, and 3) microcosm experiments with altered water/sediment conditions. Results support the hypothesis that excess nutrients play a role in both chlorophyll a and enterococci levels. For the St. Lucie River, analyses indicate that chlorophyll a correlated significantly with total Kjeldahl nitrogen (TKN) (R² = 0.30, p = 0.008) and the strongest model for enterococci included nitrate-nitrite, TKN, total phosphorus, orthophosphorus, and turbidity in our long-term analysis (n = 39, R² = 0.83, p ≤ 0.001). The microcosm results indicated that chlorophyll a and enterococci only persisted for 36 h in water from all sources, and that sediments from Lake Okeechobee may have allowed for sustained levels of chlorophyll a and enterococci levels. Overall similarities were observed in chlorophyll a and enterococci relationships with nutrient concentrations regardless of a Lake Okeechobee connection, as underscored by a study of flow out of the lake and downstream areas. This suggests that both nutrient-rich lake water and untreated surface water runoff contribute to microalgae blooms and enterococci exceedances in southeast Florida.

Potential Hydrodynamic Cytoplasmic Transfer between Mammalian Cells: Cell-Projection Pumping

We earlier reported cytoplasmic fluorescence exchange between cultured human fibroblasts (Fibs) and malignant cells (MCs). Others report similar transfer via either tunneling nanotubes (TNTs) or shed membrane vesicles, and this changes the phenotype of recipient cells. Our time-lapse microscopy showed most exchange was from Fibs into MCs, with less in the reverse direction. Although TNTs were seen, we were surprised transfer was not via TNTs but was instead via fine and often branching cell projections that defied direct visual resolution because of their size and rapid movement. Their structure was revealed nonetheless by their organellar cargo and the grooves they formed indenting MCs, which was consistent with holotomography. Discrete, rapid, and highly localized transfer events evidenced against a role for shed vesicles. Transfer coincided with rapid retraction of the cell projections, suggesting a hydrodynamic mechanism. Increased hydrodynamic pressure in retracting cell projections normally returns cytoplasm to the cell body. We hypothesize "cell-projection pumping" (CPP), in which cytoplasm in retracting cell projections partially equilibrates into adjacent recipient cells via microfusions that form temporary intercellular cytoplasmic continuities. We tested plausibility for CPP by combined mathematical modeling, comparison of predictions from the model with experimental results, and then computer simulations based on experimental data. The mathematical model predicted preferential CPP into cells with lower cell stiffness, expected from equilibration of pressure toward least resistance. Predictions from the model were satisfied when Fibs were cocultured with MCs and fluorescence exchange was related to cell stiffness by atomic force microscopy. When transfer into 5000 simulated recipient MCs or Fibs was studied in computer simulations, inputting experimental cell stiffness and donor cell fluorescence values generated transfers to simulated recipient cells similar to those seen by experiment. We propose CPP as a potentially novel mechanism in mammalian intercellular cytoplasmic transfer and communication.

Cow-level risk factors for reproductive tract disease diagnosed by 2 methods in pasture-grazed dairy cattle in Ireland

The cow-side diagnosis of reproductive tract disease (RTD) involves identifying the presence of purulent vaginal discharge (PVD) and ultrasonographic endometritis (UE). The objectives of our study were to obtain prevalence estimates for RTD diagnosed by 2 methods (PVD and UE scoring) and to investigate the risk factors for increased probability of RTD if these methods are used in isolation or in combination. Our retrospective observational cohort study tested the hypothesis that RTD assessed by 2 methods would have similar risk factors, and that those would be mainly cow- and calving-related factors. We analyzed data from 5,049 pre-breeding examinations (PBE) from 2,460 spring-calved cows on 8 farms between 2014 and 2018. Cow-related details assessed were days in milk at PBE, breed, lactation number, dry period length, body condition score at calving and PBE, 305-d milk yield, predicted transmitting ability for production and fertility, the presence of a corpus luteum at PBE, and positive diagnosis the previous year. Calving details assessed were type of sire, calf sex, twinning, stillbirth, calving difficulty score, and retained fetal membranes. We conducted statistical analyses using 4 multivariable logistic regression models to identify the risk of RTD diagnosed by (1) PVD in isolation, (2) UE in isolation, (3) the presence of either PVD or UE; and (4) the presence of both PVD and UE. We accounted for herd, cow, and year as random effects in all 4 models. The overall prevalence of RTD in models 1, 2, 3, and 4 were 7.5, 6.7, 11.6, and 2.6%, respectively. Days in milk at PBE, the interaction between days in milk and retained fetal membranes, twinning, and the predicted transmitting ability for calving interval were consistently significant risk factors for positive scores in all 4 models. Considerable calving difficulty [adjusted odds ratio (AOR) = 13.64], Holstein Friesian dam breed (AOR = 2.58), first lactation (AOR = 2.39), and body condition score at PBE (AOR = 1.64) were risk factors for a positive PVD score but not for a positive UE score. Fifth lactation (AOR = 1.69), a beef-sired calf (AOR = 1.46), and the absence of a corpus luteum at PBE (AOR = 1.57) were risk factors for a positive UE score but not for a positive PVD score. These results support the hypothesis that most of the risk factors for PVD and UE are the same but some are distinctly different, implying that in some instances the 2 methods diagnose separate components of the RTD complex.

Increased cell size, structural complexity and migration of cancer cells acquiring fibroblast organelles by cell-projection pumping

We recently described a hydrodynamic mechanism for cytoplasmic transfer between cells, termed cell-projection pumping (CPP). Earlier image analysis related altered SAOS-2 osteosarcoma cell morphology, to what we now recognize as CPP uptake of fibroblast cytoplasm. We here examine SAOS-2 phenotype following co-culture with human dermal fibroblasts (HDF) in which organelles were pre-labelled with a fluorescent lipophilic marker. Fluorescence activated cell sorting (FACS) analysis was performed of HDF and SAOS-2, cultured either alone or together. FACS forward scatter is proportionate to cell size, and increased for SAOS-2 with high levels of HDF fluorescence uptake (p < 0.004). FACS side scatter is proportionate to internal cell complexity, and increased in SAOS-2 with increasing uptake of HDF fluorescence (p < 0.004), consistent with uptake of HDF organelles. Scratch migration assays revealed that HDF migrated more quickly than SAOS-2 in both isolated cell culture, and following co-culture (p < 0.004). Notably, SAOS-2 with high levels of HDF labelling migrated faster compared with SAOS-2 with low HDF labelling (p < 0.008). A slight and unconvincing reduction in SAOS-2 proliferation was seen (p < 0.02). Similar results were obtained in single additional experiments with A673 and H312 cancer cells. Forward and side scatter results suggest organellar transfer by CPP increases cancer cell morphological diversity. This may contribute to histological pleomorphism relevant to cancer diagnosis and prognosis. Also, increased migration of sub-populations of cancer cells with high CPP organellar uptake, may contribute to invasion and metastasis in-vivo. We thus suggest relevance of CPP to cancer diagnosis and progression.

Hepatitis C virus screening and treatment in Irish prisons from nurse managers' perspectives - a qualitative exploration

Background

Prisoners carry a greater burden of physical, communicable and psychiatric disease compared to the general population. Prison health care structures are complex and provide challenges and opportunities to engage a marginalised and poorly served group with health care including Hepatitis C Virus (HCV) screening, assessment and treatment. Optimising HCV management in prisons is a public health priority. Nurses are the primary healthcare providers in most prisons globally. Understanding the barriers and facilitators to prisoners engaging in HCV care from the perspectives of nurses is the first step in implementing effective strategies to eliminate HCV from prison settings. The aim of this study was to identify the barriers and facilitators to HCV screening and treatment in Irish prisons from a nurse perspective and inform the implementation of a national prison-based HCV screening program.

Methods

A qualitative study using focus group methodology underpinned by grounded theory for analysis in a national group of nurse managers (n = 12).

Results

The following themes emerged from the analysis; security and safety requirements impacting patient access, staffing and rostering issues, prison nurses’ skill set and concerns around phlebotomy, conflict between maintaining confidentiality and concerns for personal safety, peer workers, prisoners’ lack of knowledge, fear of treatment and stigma, inter-prison variations in prisoner health needs and health service delivery and priority, linkage to care, timing of screening and stability of prison life.

Conclusions

Prison nurses are uniquely placed to identify barriers and facilitators to HCV screening and treatment in prisoners and inform changes to health care practice and policy that will optimise the public health opportunity that incarceration provides.

Hepatitis C virus screening and treatment in Irish prisons from a governor and prison officer perspective - a qualitative exploration

BACKGROUND

Prisons are a key location to access Hepatitis C Virus (HCV) infected people who inject drugs (PWID). Prison health care structures are complex and optimising health care delivery to this high need, marginalised and underserved population remains challenging. Despite international guidelines recommending that prisons are a priority location for HCV screening and treatment levels of prisoner engagement in HCV care remain low. Competing priorities between security and healthcare is a key feature of prison health care. A collaborative approach to health care delivery in prisons can maximise the benefits for prisoners, staff and the wider community.

AIM

To identify the barriers and enablers to HCV screening and treatment in Irish prisons and inform the implementation of a HCV screening program within the Irish Prison Services (IPS).

METHODS

Qualitative study using focus group methodology underpinned by grounded theory.

RESULTS

The following themes emerged from the analysis: priority of safety and security, staffing and resources, concerns about personal risk, lack of knowledge, concerns around confidentiality, prisoners' fear of treatment and stigma, timing of screening, use of peer workers, in-reach hepatology and fibroscanning services. The primary role of prison security is to ensure the safety of staff and prisoners with a secondary but important supporting role in health care delivery. Maintaining adequate staffing levels and the provision of training and education were seen as priorities and impacted on prison officers' fear for personal safety and risk of HCV transmission. Opt-out screening and peer support workers had high levels of support among participants.

CONCLUSION

Upscaling HCV management in prisons requires an in-depth understanding of all barriers and facilitators to HCV screening and treatment. Engaging prison officers in the planning and delivery of health care initiatives is a key strategy to optimising the public health opportunity that prisons provides.

Diacylglycerol kinase (DGKA) regulates the effect of the epilepsy and bipolar disorder treatment valproic acid in Dictyostelium discoideum

Valproic acid (VPA) provides a common treatment for both epilepsy and bipolar disorder; however, common cellular mechanisms relating to both disorders have yet to be proposed. Here, we explore the possibility of a diacylglycerol kinase (DGK) playing a role in regulating the effect of VPA relating to the treatment of both disorders, using the biomedical model Dictyostelium discoideum. DGK enzymes provide the first step in the phosphoinositide recycling pathway, implicated in seizure activity. They also regulate levels of diacylglycerol (DAG), thereby regulating the protein kinase C (PKC) activity that is linked to bipolar disorder-related signalling. Here, we show that ablation of the single Dictyostelium dgkA gene results in reduced sensitivity to the acute effects of VPA on cell behaviour. Loss of dgkA also provides reduced sensitivity to VPA in extended exposure during development. To differentiate a potential role for this DGKA-dependent mechanism in epilepsy and bipolar disorder treatment, we further show that the dgkA null mutant is resistant to the developmental effects of a range of structurally distinct branched medium-chain fatty acids with seizure control activity and to the bipolar disorder treatment lithium. Finally, we show that VPA, lithium and novel epilepsy treatments function through DAG regulation, and the presence of DGKA is necessary for compound-specific increases in DAG levels following treatment. Thus, these experiments suggest that, in Dictyostelium, loss of DGKA attenuates a common cellular effect of VPA relating to both epilepsy and bipolar disorder treatments, and that a range of new compounds with this effect should be investigated as alternative therapeutic agents.

This article has an associated First Person interview with the first author of the paper.

Editor's choice: Here, using a tractable model system, Dictyostelium discoideum, we show that diacylglycerol kinase activity might contribute to the cellular mechanism of action of the epilepsy and bipolar disorder treatment, valproic acid.

A method for investigating the cellular response to cyclic tension or compression in three-dimensional culture

We have an interest in the cellular response to mechanical stimuli, and here describe an in-vitro method to examine the response of cells cultured in a three-dimensional matrix to mechanical compressive and tensile stress. Synthetic aliphatic polyester scaffolds coated with 45S5 bioactive glass were seeded with human dental follicular cells (HDFC), and attached to well inserts and magnetic endplates in six well palates. Scaffolds were subjected to either cyclic 10% tensile deformation, or 8% compression, at 1 Hz and 2 Hz respectively for 6, 24 or 48 h, by uniaxial motion of magnetically-coupled endplates. It was possible to isolate high quality mRNA from cells in these scaffolds, as demonstrated by high RNA integrity numbers scores, and ability to perform meaningful cRNA microarray analysis, in which 669 and 727 genes were consistently upregulated, and 662 and 518 genes down regulated at all times studied under tensile and compressive loading conditions respectively. MetaCore analysis revealed the most regulated gene ontogenies under both loading conditions to be for: cytoskeletal remodelling; cell adhesion-chemokines and adhesion; cytoskeleton remodelling-TGF WNT and cytoskeletal remodelling pathways. We believe the method here described will be of value for analysis of the cellular response to cyclic loading.

Inhibitory Effects of Angiotensin II Receptor Blockade on Human Tenon Fibroblast Migration and Reactive Oxygen Species Production in Cell Culture

Purpose

We investigate the effect of angiotensin receptor blockade on the migration of human Tenon fibroblasts (HTF), using irbesartan, an angiotensin II receptor type 1 (AT1R) blocker (ARB) as a potential antifibrotic agent in glaucoma filtration surgery.

Methods

Confluent HTF cultures were scratched with a 1 mL pipette tip and treated with either irbesartan (10, 50, and 100 μg/mL) or angiotensin II (2 μg/mL). The extent of HTF migration up to 30 hours, and cell number and morphology at 72 hours was evaluated. To assess the effect on reactive oxygen species (ROS) level, HTF were treated with either irbesartan (10 μg/mL) or angiotensin II (2 μg/mL) for 24 hours after scratching, and then stained with dihydroethidium (DHE) before evaluation by confocal microscopy.

Results

Irbesartan inhibited HTF migration by 50% to 70% compared to controls (P < 0.05). Levels of ROS were almost completely attenuated by irbesartan (DHE fluorescence intensity of 5.68E-09) (P < 0.05). Irbesartan reduced cell numbers by 50% and induced morphologic changes with loss of pseudopods (P < 0.05). Conversely, angiotensin II increased cell numbers up to 4-fold while retaining cell viability.

Conclusions

Irbesartan inhibited HTF migration and ROS production. It also reduced cell numbers and altered HTF morphology. Angiotensin II increased cell number without altering morphology. This initial study warrants future investigations for further potential antifibrotic effects of this drug.

Translational Relevance

This in vitro study focused on investigations of irbesartan's effects on HTF migration, ROS production, as well as HTF cell numbers and morphology. It suggests a potential therapeutic strategy worth further exploration with a view towards postoperative wound healing modulation in glaucoma filtration surgery.