Model for End-Stage Liver Disease/Pediatric End-Stage Liver Disease exception policy and outcomes in pediatric patients with hepatopulmonary syndrome requiring liver transplantation.

Hepatopulmonary syndrome (HPS) is associated with increased waitlist mortality in liver transplantation (LT) candidates. Children with HPS are granted Model for End-Stage Liver Disease (MELD)/Pediatric End-Stage Liver Disease (PELD) exception points for waitlist prioritization in the United States based on criterion developed for adults. In this study, the impact of this MELD/PELD exception policy on post-LT survival in children was examined. A retrospective cohort of patients aged younger than 18 years with a MELD/PELD exception request who underwent LT between 2007 and 2018 were identified in the Scientific Registry of Transplant Recipients. Patients were stratified by waitlist partial pressure of arterial oxygen (PaO 2 ) to assess risk factors for waitlist mortality and post-LT survival. Among 3082 pediatric LT recipients included in the study, 124 patients (4%) received MELD/PELD exception points for HPS. Patients with HPS were a median age of 9 years (interquartile range: 6, 12 years), 54.8% were girls, and 54% were White. Most patients (87.9%) were listed with laboratory MELD/PELD scores <15. Waitlist mortality for patients with HPS exception points was rare and not different from patients without HPS. When stratified by pre-LT PaO 2 , hypoxemia severity was not associated with differences in 1-, 3-, or 5-year survival rates after LT ( p = 0.13). However, patients with HPS showed a slightly lower survival rate at 5 years compared with patients without HPS (88.7% vs. 93.4%; p = 0.04). MELD/PELD exceptions for children with HPS mitigated waitlist mortality, and recipients with HPS experienced excellent 5-year survival after LT, although slightly lower than in patients without HPS. Unlike adults with HPS, the severity of pre-LT hypoxemia in children does not impact post-LT survival. These data suggest that adult criteria for granting MELD/PELD exception points may not appropriately capture HPS severity in pediatric patients. Further prospective multicenter studies to examine the risk factors predicting negative survival outcomes in children with HPS are warranted.

Evaluation of Fontan-associated Liver Disease and Ethnic Disparities in Long-term Survivors of the Fontan Procedure: A Population-based Study.

OBJECTIVES: Fontan-associated liver disease (FALD) has emerged as a nearly universal chronic comorbidity in patients with univentricular congenital heart disease who undergo the Fontan procedure. There is a paucity of data reporting long-term outcomes and the impact of FALD in this population. METHODS: Patients who underwent the Fontan procedure between 1992 and 2018 were identified using California registry data. Presumed FALD was assessed by a composite of liver disease codes. Primary outcomes were mortality and transplant. Multivariable regression and survival analyses were performed. RESULTS: Among 1436 patients post-Fontan, 75.9% studied were adults, with a median follow-up of 12.6 (8.4, 17.3) years. The population was 46.3% Hispanic. Overall survival at 20 years was >80%, but Hispanic patients had higher mortality risk compared with White patients [hazard ratio: 1.49 (1.09-2.03), P =0.012]. Only 225 patients (15.7%) had presumed FALD, although >54% of patients had liver disease by age 25. FALD was associated with later deaths [median: 9.6 (6.4-13.2) years post-Fontan] compared with patients who died without liver disease [4.1 (1.4-10.4) years, P =0.02]. Patients with FALD who underwent combined heart liver transplant had 100% survival at 5 years, compared with only 70.7% of patients who underwent heart transplant alone. CONCLUSIONS: In this population-based analysis of long-term outcomes post-Fontan, Hispanic ethnicity was associated with increased all-cause mortality. Further, the prevalence of FALD is underrecognized, but our data confirms that its incidence increases with age. FALD is associated with late mortality but excellent posttransplant survival. This emphasizes the need for FALD-specific liver surveillance strategies in patients post-Fontan.

Clinical Value of Surveillance Biopsies in Pediatric Liver Transplantation.

Although pediatric liver transplantation (LT) results in excellent long-term outcomes, a high incidence of early acute cellular rejection and late graft fibrosis persists. Routine measurement of allograft enzymes may not reliably detect rejection episodes, identify candidates for immunosuppression minimization, or indicate allograft fibrosis. Surveillance biopsies (SBs) can provide valuable information in this regard, but their role in pediatric LT is not fully established. A retrospective cohort of 236 pediatric LT recipients from a high-volume center was studied to characterize the risks and benefits of SB versus for-cause biopsies (FCBs). The study population was 47.1% male and 54.7% Hispanic, and 31% received living donor grafts. Our data suggest that patients in the SB group had better transplant outcomes (rejection-free, graft, and patient survival) compared with patients who had FCBs or who never underwent biopsy. Among 817 biopsies obtained from 236 patients, 150 (18.4%) were SBs. Only 6 patients had a biopsy-related complication, and none were observed in the SB subset. Graft biochemical blood tests did not accurately predict rejection severity on biopsy, with aspartate aminotransferase area under the receiver operating characteristic curve (AUROC) 0.66, alanine aminotransferase AUROC 0.65 (very poor predictions), and gamma-glutamyltransferase AUROC 0.58 (no prediction). SBs identified subclinical rejection in 18.6% of biopsies, whereas 63.3% of SBs had evidence of fibrosis. SBs prompted changes in immunosuppression including dose reduction. Our experience suggests that SB in pediatric LT is safe, offers valuable information about subclinical rejection episodes, and can guide management of immunosuppression, including minimization. Improved outcomes with SB were likely multifactorial, potentially relating to a more favorable early posttransplant course and possible effect of management optimization through SB. Further multicenter studies are needed to examine the role of SBs on long-term outcomes in pediatric LT.

A study of longitudinal trends in time-frequency transformations of EEG data during a learning experiment.

EEG experiments yield high-dimensional event-related potential (ERP) data in response to repeatedly presented stimuli throughout the experiment. Changes in the high-dimensional ERP signal throughout the duration of an experiment (longitudinally) is the main quantity of interest in learning paradigms, where they represent the learning dynamics. Typical analysis, which can be performed in the time or the frequency domain, average the ERP waveform across all trials, leading to the loss of the potentially valuable longitudinal information in the data. Longitudinal time-frequency transformation of ERP (LTFT-ERP) is proposed to retain information from both the time and frequency domains, offering distinct but complementary information on the underlying cognitive processes evoked, while still retaining the longitudinal dynamics in the ERP waveforms. LTFT-ERP begins by time-frequency transformations of the ERP data, collected across subjects, electrodes, conditions and trials throughout the duration of the experiment, followed by a data driven multidimensional principal components analysis (PCA) approach for dimension reduction. Following projection of the data onto leading directions of variation in the time and frequency domains, longitudinal learning dynamics are modeled within a mixed effects modeling framework. Applications to a learning paradigm in autism depict distinct learning patterns throughout the experiment among children diagnosed with Autism Spectrum Disorder and their typically developing peers. LTFT-ERP time-frequency joint transformations are shown to bring an additional level of specificity to interpretations of the longitudinal learning patterns related to underlying cognitive processes, which is lacking in single domain analysis (in the time or the frequency domain only). Simulation studies show the efficacy of the proposed methodology.

Treatment and outcomes of hepatocellular carcinoma in patients with Sickle cell disease: a population-based study in the U.S.

BACKGROUND: Sickle cell disease (SCD) is a rare hemoglobinopathy which can result in chronic liver disease and cirrhosis. Patients with SCD have an increased risk of hematologic malignancy, but the prevalence of hepatocellular carcinoma (HCC) in this population is unknown. Herein, the association of SCD with HCC was examined using registry data. METHODS: The SEER-Medicare database was queried to identify patients diagnosed with HCC between 2000 and 2015, and further stratified by SCD status. Propensity matching was performed to examine cancer-related survival and treatment outcomes. RESULTS: Overall 56,934 patients with HCC were identified, including 81 patients with SCD. Patients with SCD more frequently had cirrhosis [48.1% (39/81) vs 23.5% (13,377/56,853), p < 0.01] yet presented with smaller tumors [<5 cm: 51.9% (42/81) vs 38.5% (21,898/56,853), p = 0.01]. After propensity matching, SCD was not associated with attenuated survival (aHR 0.73 95%CI 0.52-1.01). When stratified by treatment, patients with SCD had equivalent outcomes to chemotherapy (p = 0.65), TACE/TARE (p = 0.35), resection (p = 0.15) and transplantation (p = 0.67) when compared to non-SCD patients. CONCLUSION: This study confirms that a subset of patients with SCD will develop HCC. Importantly, therapeutic options for HCC should not be limited by pre-existing SCD, and similar survival should be expected when compared to non-SCD patients.

Optimizing Screening for Anorectal, Pharyngeal, and Urogenital Chlamydia trachomatis and Neisseria gonorrhoeae Infections in At-Risk Adolescents and Young Adults in New Orleans, Louisiana and Los Angeles, California, United States.

BACKGROUND: Public health organizations have inconsistent recommendations for screening adolescents and young adults for Chlamydia trachomatis and Neisseria gonorrhoeae infections. Guidelines suggest different combinations of anorectal, pharyngeal, and urogenital testing based on age, sex, and sexual activity. Further evaluation of how identity and behaviors impact the anatomic distribution of C. trachomatis and N. gonorrhoeae infection is needed to optimize future screening practices. METHODS: We assessed the positivity of C. trachomatis and N. gonorrhoeae infections at different anatomic sites in a cohort of at-risk sexually active adolescents and young adults aged 12-24 years in New Orleans, Louisiana and Los Angeles, California. Participants were tested for C. trachomatis and N. gonorrhoeae at 3 sites (anorectum, pharynx, and urethral/cervix) every 4 months using self-collected swabs. We stratified anatomic distributions of infection into 4 gender and sexual behavior categories: (1) cisgender men who have sex with men and transgender women (MSMTW); (2) cisgender heterosexual males; (3) cisgender heterosexual females; and (4) gender minorities assigned female at birth. RESULTS: While three-site testing detected all infections, two-site (anorectum and urethra/cervix) testing identified 92%-100% of C. trachomatis or N. gonorrhoeae infections in participants assigned female at birth and cisgender heterosexual males. For MSMTW, two-site anorectal and pharyngeal testing vs single-site anorectal testing increased the proportion of individuals with either infection from 74% to 93%. CONCLUSIONS: Sexual behavior and gender identity may influence detection of C. trachomatis and N. gonorrhoeae infections at specific anatomic testing sites. Testing guidelines should incorporate sexual behavior and gender identity. CLINICAL TRIALS REGISTRATION: NCT03134833.

Assessment of the global practice of living donor liver transplantation.

Criteria that drive the selection and utilization of living liver donors are limited. Herein, the global availability of living donor liver transplantation (LDLT) and components of donor selection and utilization were assessed via an international survey. There were 124 respondents representing 41 countries, including 47 from Asia/Middle East (A/ME), 20 from Europe, and 57 from the Americas. Responses were obtained from 94.9% of countries with ≥10 LDLT cases/year. Most centers (82.3%) have defined donor age criteria (median 18-60 years), while preset recipient MELD cutoffs (median 18-30) were only reported in 54.8% of programs. Overall, 67.5% of programs have preset donor BMI (body mass index) ranges (median 18-30), and the mean acceptable macrosteatosis was highest for A/ME (20.2 ± 9.2%) and lowest for Americas (16.5 ± 8.4%, P = 0.04). Americas (56.1%) and European (60.0%) programs were more likely to consider anonymous donors versus A/ME programs (27.7%, P = 0.01). There were no differences in consideration of complex anatomical variations. Most programs (75.9%) perform donor surgery via an open approach, and A/ME programs are more likely to use microscopic arterial reconstruction. Despite variations in practice, key aspects of living donor selection were identified. These findings provide a contemporary reference point as LDLT continues to expand into areas with limited access to liver transplantation.

Using Machine Learning to Predict Young People's Internet Health and Social Service Information Seeking.

Machine learning creates new opportunities to design digital health interventions for youth at risk for acquiring HIV (YARH), capitalizing on YARH's health information seeking on the internet. To date, researchers have focused on descriptive analyses that associate individual factors with health-seeking behaviors, without estimating of the strength of these predictive models. We developed predictive models by applying machine learning methods (i.e., elastic net and lasso regression models) to YARH's self-reports of internet use. The YARH were aged 14-24 years old (N = 1287) from Los Angeles and New Orleans. Models were fit to three binary indicators of YARH's lifetime internet searches for general health, sexual and reproductive health (SRH), and social service information. YARH responses regarding internet health information seeking were fed into machine learning models with potential predictor variables based on findings from previous research, including sociodemographic characteristics, sexual and gender minority identity, healthcare access and engagement, sexual behavior, substance use, and mental health. About half of the YARH reported seeking general health and SRH information and 26% sought social service information. Areas under the ROC curve (≥ .75) indicated strong predictive models and results were consistent with the existing literature. For example, higher education and sexual minority identification was associated with seeking general health, SRH, and social service information. New findings also emerged. Cisgender identity versus transgender and non-binary identities was associated with lower odds of general health, SRH, and social service information seeking. Experiencing intimate partner violence was associated with higher odds of seeking general health, SRH, and social service information. Findings demonstrate the ability to develop predictive models to inform targeted health information dissemination strategies but underscore the need to better understand health disparities that can be operationalized as predictors in machine learning algorithms.

Community-based Implementation of Centers for Disease Control and Prevention's Recommended Screening for Sexually Transmitted Infections Among Youth at High Risk for HIV Infection in Los Angeles and New Orleans.

We examined whether the implementation of the Centers for Disease Control and Prevention's recommended screening of Chlamydia trachomatis/Neisseria gonorrhoeae with proactive follow-up among high-risk youth recruited from community and clinic settings reduced future C. trachomatis/N. gonorrhoeae diagnoses. After the Centers for Disease Control and Prevention's recommendations demonstrated a 41% decline in sexually transmitted infections; 3 tests in 1 year resulted in a 10% decline.

High Lifetime Prevalence of Syphilis in Men Who Have Sex With Men and Transgender Women Versus Low Lifetime Prevalence in Female Sex Workers in Lima, Peru.

BACKGROUND: The syphilis epidemic continues to cause substantial morbidity worldwide and is worsening despite ongoing control efforts. Syphilis remains an important public health problem among 3 key populations: men who have sex with men (MSM), transgender women, and female sex workers. METHODS: We conducted a retrospective chart review of patients that received rapid point-of-care treponemal antibody tests from January 2019 to July 2019 in 4 sexually transmitted infection (STI) clinics in Lima, Peru. We assessed patient medical records for human immunodeficiency virus (HIV) infection, history of STIs, as well as sociodemographic and behavioral characteristics. Cross-sectional descriptive analyses were used to determine factors associated with treponemal positivity. RESULTS: We included 401 patient records in our analyses: 252 MSM, 31 transgender women, and 118 female sex workers. The overall median age of patients was 29.0 years (interquartile range, 24.0-36.0 years). Positivity on the treponemal test was 28.9% (95% confidence interval [CI], 24.3%-33.3%) overall, 37.7% (95% CI, 31.7%-44.0%) for MSM, 54.8% (95% CI, 36.0%-72.7%) for transgender women, and 3.4% (95% CI, 0.9%-8.5%) for female sex workers. In the bivariate analysis, treponemal positivity was also associated with receptive anal sex in the last 6 months in MSM (P < 0.01). Additionally, treponemal positivity increased with age (P = 0.0212) and varied by socioeconomic status (P < 0.01). Multivariate Least Absolute Shrinkage and Selection Operator logistic regression showed that treponemal positivity was highly associated with HIV coinfection (adjusted odds ratio, 5.42) and previous STI other than HIV or syphilis (adjusted odds ratio, 1.54). CONCLUSIONS: A review of the medical records of members of 3 key populations who had recently received a rapid point-of-care treponemal test in Lima, Peru, revealed that lifetime prevalence of syphilis was high among MSM and transgender women, but low among female sex workers. Those results may indicate a need for more frequent, regular testing among MSM and transgender women-possibly in conjunction with HIV testing, and appropriate treatment of those shown to be positive.

Safety and Effectiveness of Same-Day Chlamydia trachomatis and Neisseria gonorrhoeae Screening and Treatment Among Gay, Bisexual, Transgender, and Homeless Youth in Los Angeles, California, and New Orleans, Louisiana.

BACKGROUND: Gay, bisexual, transgender, and homeless youth are at risk of sexually transmitted infections. As part of an adolescent human immunodeficiency virus prevention study, we provided same-day Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) testing and treatment. We aimed to evaluate the feasibility and effectiveness of same-day CT and NG treatment on the proportion of participants receiving timely treatment. METHODS: We recruited adolescents with high sexual risk behaviors aged 12 to 24 years from homeless shelters, lesbian, gay, bisexual, and transgender organizations, and community health centers in Los Angeles, California, and New Orleans, Louisiana from May 2017 to June 2019. Initially, participants were offered point-of-care pharyngeal, rectal, and urethral/vaginal CT and NG testing and referral to another clinic for treatment. After March 2018 in Los Angeles and November 2018 in New Orleans, we provided same-day treatment (and partner treatment packs) for study participants. We measured the proportion of participants who received same-day treatment and the median time to treatment. We collected frequency of partner treatment and any reported adverse treatment-related events. RESULTS: The proportion of participants receiving same-day CT and NG treatment increased from 3.6% (5/140) to 21.1% (20/95; Δ17.5%; 95% confidence interval, 9.2%-26.9%) after implementation of same-day testing and treatment. The median time to treatment decreased from 18.5 to 3 days. Overall, 36 participants took a total of 48 partner treatment packs. There were no reported treatment-related adverse events. CONCLUSIONS: Providing sexually transmitted infection treatment to adolescents at the same visit as testing is feasible and safe, and can increase the proportion of individuals receiving timely treatment.

Associations between violence, criminality, and cognitive control deficits among young men living in low resource communities in South Africa.

Despite empirical support for "Self-control theory" in criminology, there is controversy about how self-control should be operationalized. Working within the framework of "self-control theory," we investigated if violence and criminal behaviors are associated with nine distinct dimensions of cognitive control in a community sample of young men (n = 654) living in peri-urban townships in South Africa. Cognitive control was assessed using the Behavior Rating Inventory of Executive Function. Multivariate statistical analysis was used, to identify associations between violence and criminality, and deaggregated measures of nine distinct components of cognitive control. Fifteen percent of the sample reported recent violence, 27% had been in physical fights with family/friends in the preceding 6 months, 10% reported being arrested, 4% reported forced sexual contact, and 26% reported intimate partner violence (IPV). Controlling for substance use and sociodemographic variables, contact with the criminal justice system and violence were associated with deficits in all domains of cognitive control. Forced sexual contact was associated with behavioral dysregulation. IPV was associated with behavior dysregulation and executive control dysfunction. Future studies might utilize deaggregated measures of self-control to provide further insight into links between particular components of cognitive control and various forms of offending and violence.

A distinct class of vesicles derived from the trans-Golgi mediates secretion of xylogalacturonan in the root border cell.

Root border cells lie on the surface of the root cap and secrete massive amounts of mucilage that contains polysaccharides and proteoglycans. Golgi stacks in the border cells have hypertrophied margins, reflecting elevated biosynthetic activity to produce the polysaccharide components of the mucilage. To investigate the three-dimensional structures and macromolecular compositions of these Golgi stacks, we examined high-pressure frozen/freeze-substituted alfalfa root cap cells with electron microscopy/tomography. Golgi stacks in border cells and peripheral cells, precursor cells of border cells, displayed similar morphological features, such as proliferation of trans cisternae and swelling of the trans cisternae and trans-Golgi network (TGN) compartments. These swollen margins give rise to two types of vesicles larger than other Golgi-associated vesicles. Margins of trans-Golgi cisternae accumulate the LM8 xylogalacturonan (XGA) epitope, and they become darkly stained large vesicles (LVs) after release from the Golgi. Epitopes for xyloglucan (XG), polygalacturonic acid/rhamnogalacturonan-I (PGA/RG-I) are detected in the trans-most cisternae and TGN compartments. LVs produced from TGN compartments (TGN-LVs) stained lighter than LVs and contained the cell wall polysaccharide epitopes seen in the TGN. LVs carrying the XGA epitope fuse with the plasma membrane only in border cells, whereas TGN-LVs containing the XG and PGA/RG-I epitopes fuse with the plasma membrane of both peripheral cells and border cells. Taken together, these results indicate that XGA is secreted by a novel type of secretory vesicles derived from trans-Golgi cisternae. Furthermore, we simulated the collapse in the central domain of the trans-cisternae accompanying polysaccharide synthesis with a mathematical model.

Examining the Role for Donor-specific Antibody Testing in Simultaneous Liver-kidney Transplantation: A Single-center Analysis of Outcomes.

BACKGROUND: Simultaneous liver-kidney transplantation (SLKT) is increasingly used for patients with concurrent end-stage liver and renal disease. Emerging evidence suggests that simultaneous liver transplant can provide a tolerogenic benefit to multiorgan transplant recipients. Posttransplant donor-specific antibody (DSA) may be associated with worse outcomes; however, the role for testing DSA in SLKT is unclear. METHODS: This study retrospectively assessed the impact of DSA on outcomes following primary SLKT at a large-volume center between 2008 and 2018. Patients were grouped by positive DSA, negative DSA, and DSA not tested, and data were obtained from our institutional database and chart review. RESULTS: The cohort included 138 SLKT recipients with a mean age of 56.1 ± 9.7 y; 61.6% were male, and 55.8% were Hispanic. Overall, 62 patients were tested for DSA posttransplant, and 33 patients (23.9%) had at least 1 DSA detected. A total of 34 patients (24.6%) experienced at least 1 episode of liver rejection, and 23 patients (16.7%) experienced kidney rejection. Over 50% of patients with de novo DSA changed status during their posttransplant course. Rates of both liver and kidney rejection were slightly higher in the DSA + group, but liver allograft, kidney allograft, and patient survival did not differ when grouped by whether DSA testing was performed or DSA positivity. CONCLUSIONS: These data demonstrate that SLKT is associated with excellent long-term patient and allograft survival with a relatively low rate of rejection. In our experience, testing for DSA does not impact SLKT outcomes' and further multicenter analyses are needed to establish standard of care.

Evaluation of technical urinary tract complications in kidney transplantation recipients with a prolonged dialysis history.

BACKGROUND: The kidney transplant waiting list continues to expand, resulting in prolonged dialysis times exceeding 8 years before transplantation in some regions. The relationship between long-term dialysis and urinary tract complications after kidney transplant remains largely unexplored. This study aims to evaluate post-kidney transplant complications in patients with a history of prolonged dialysis. METHODS: A single-center, retrospective cohort study of patients maintained on dialysis ≥8 years before kidney transplant between January 2000 and July 2020 was conducted. Clinical variables, including demographics and comorbidities, were reviewed. The primary objective was the development of a technical urinary tract complication. Secondary outcomes included any postoperative complication by type, stratified by medical and surgical complications. RESULTS: Overall, 376 patients met the inclusion criteria. The mean pre-kidney transplant dialysis time was 10.2 ± 2.6 years. The majority (65.7%) of the study participants were anuric. Four patients (1.1%) experienced a urine leak, and 8 patients (2.1%) had a ureteral stricture. Any complication was observed in 111 (29.5%) patients, with urinary tract infections being the most common. Urinary catheters remained in place for a median of 4 (3, 5) days. Drains were commonly used (62.8%) for a median of 5 (4, 6) days. CONCLUSION: In our large, single-center experience with kidney transplants in high-risk patients with prolonged dialysis and anuria, the technical urinary tract complications rate remained low. With the current literature consisting of small cohorts and having relatively short pre-kidney transplant dialysis periods, our analysis addresses the shortcomings of the literature while suggesting that this patient population may not truly be "high risk."

HPV Vaccination among Sexual and Gender Minority Youth Living with or at High-Risk for HIV.

BACKGROUND: Human papillomavirus (HPV) is epidemic among young people, especially those at highest risk of acquiring HPV-related cancers. METHODS: Youth aged 14-24 years old (N = 1628) were recruited from 13 clinics, community agencies, and social media sites in Los Angeles, California, and New Orleans, Louisiana, that specialized in serving sexual and gender minority youths (SGMY), especially males at risk for HIV. A cross-sectional comparison of sociodemographic and risk histories of HPV vaccinated/unvaccinated youths was conducted using both univariate and multivariate regressions. RESULTS: About half (51.9%) of youth were vaccinated, with similar percentages across states and across genders. Sexual and gender minority youths (SGMY, i.e., gay, bisexual, transgender, and non-heterosexual; 68.8%) and their heterosexual peers (15%) were equally likely to be vaccinated (54%), even though their risk for HPV-related cancers is very different. Vaccinations were higher among younger youth, those not using condoms, youth with greater education, that possessed a primary health care provider, and youth diagnosed with HIV. Vaccinations were lower among youth that were out-of-home due to mental health inpatient hospitalization, drug treatment, homelessness, or incarceration. CONCLUSIONS: Special programs are required to target youth experiencing multiple life stressors, especially out-of-home experiences, those with less education, and without the safety net of health insurance or a provider.

Adaptation of Imaging Mass Cytometry to Explore the Single Cell Alloimmune Landscape of Liver Transplant Rejection.

Rejection continues to be an important cause of graft loss in solid organ transplantation, but deep exploration of intragraft alloimmunity has been limited by the scarcity of clinical biopsy specimens. Emerging single cell immunoprofiling technologies have shown promise in discerning mechanisms of autoimmunity and cancer immunobiology. Within these applications, Imaging Mass Cytometry (IMC) has been shown to enable highly multiplexed, single cell analysis of immune phenotypes within fixed tissue specimens. In this study, an IMC panel of 10 validated markers was developed to explore the feasibility of IMC in characterizing the immune landscape of chronic rejection (CR) in clinical tissue samples obtained from liver transplant recipients. IMC staining was highly specific and comparable to traditional immunohistochemistry. A single cell segmentation analysis pipeline was developed that enabled detailed visualization and quantification of 109,245 discrete cells, including 30,646 immune cells. Dimensionality reduction identified 11 unique immune subpopulations in CR specimens. Most immune subpopulations were increased and spatially related in CR, including two populations of CD45+/CD3+/CD8+ cytotoxic T-cells and a discrete CD68+ macrophage population, which were not observed in liver with no rejection (NR). Modeling via principal component analysis and logistic regression revealed that single cell data can be utilized to construct statistical models with high consistency (Wilcoxon Rank Sum test, p=0.000036). This study highlights the power of IMC to investigate the alloimmune microenvironment at a single cell resolution during clinical rejection episodes. Further validation of IMC has the potential to detect new biomarkers, identify therapeutic targets, and generate patient-specific predictive models of clinical outcomes in solid organ transplantation.

Association of Lower Socioeconomic Status and SARS-CoV-2 Positivity in Los Angeles, California.

OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads heterogeneously, disproportionately impacting poor and minority communities. The relationship between poverty and race is complex, with a diverse set of structural and systemic factors driving higher rates of poverty among minority populations. The factors that specifically contribute to the disproportionate rates of SARS-CoV-2 infection, however, are not clearly understood. METHODS: We evaluated SARS-CoV-2 test results from community-based testing sites in Los Angeles, California, between June and December, 2020. We used tester zip code data to link those results with United States Census report data on average annual household income, rates of healthcare coverage, and employment status by zip code. RESULTS: We analyzed 2 141 127 SARS-CoV-2 test results, of which 245 154 (11.4%) were positive. Multivariable modeling showed a higher likelihood of SARS-CoV-2 test positivity among Hispanic communities than among other races. We found an increased risk for SARS-CoV-2 positivity among individuals from zip codes with an average annual household income