Review of pediatric combined heart-liver transplantation: A roadmap to success

BACKGROUND

Combined heart-liver transplantation (CHLT) is a promising technique to address end stage organ failure in patients with concomitant heart failure and chronic liver disease. While most experience with CHLT has involved adult patients, the expanding population of children born with univentricular congenital heart disease who underwent the Fontan procedure and develop Fontan-associated liver disease (FALD) has emerged as a growing indication for pediatric CHLT.

METHODS

Currently, CHLT is performed at a select subset of experienced transplant centers, especially in the pediatric population.

RESULTS

While technically demanding, CHLT may offer survival benefit when compared to heart transplant alone with decreased rejection of both synchronous allografts and equivalent outcomes with respect to waitlist time and post-operative complications. Limitations in the technique can be attributed to need for an appropriate multidisciplinary care center, challenges with donor organ availability and allocation, and the complexity associated with patient selection and peri-operative management.

CONCLUSION

In this review, we summarize the history of CHLT, discuss patient selection, and highlight key facets of peri-operative care in the pediatric population.

Impact of gut microbiota on liver transplantation

The gut microbiota has been gaining attention due to its interactions with the human body and its role in pathophysiological processes. One of the main interactions is the "gut-liver axis," in which disruption of the gut mucosal barrier seen in portal hypertension and liver disease can influence liver allograft function over time. For example, in patients who are undergoing liver transplantation, preexisting dysbiosis, perioperative antibiotic use, surgical stress, and immunosuppressive use have each been associated with alterations in gut microbiota, potentially impacting overall morbidity and mortality. In this review, studies exploring gut microbiota changes in patients undergoing liver transplantation are reviewed, including both human and experimental animal studies. Common themes include an increase in Enterobacteriaceae and Enterococcaceae species and a decrease in Faecalibacterium prausnitzii and Bacteriodes, while a decrease in the overall diversity of gut microbiota after liver transplantation.

Prophylactic Absorbable Antibiotic Beads for High-risk, Implant-based Prepectoral Reconstruction

Infections are problematic in postmastectomy implant-based reconstruction with infection rates as high as 30%. Strategies to reduce the risk of infection have demonstrated various efficacies. A prolonged course of systemic, oral antibiotics has not shown evidence-based benefit. Although absorbable antibiotic beads have been described for orthopedic procedures and pressure wounds, their use has not been well studied during breast reconstruction, particularly for prepectoral implant placement. The purpose of this study was to evaluate the selective use of prophylactic absorbable calcium sulfate antibiotic beads during high-risk implant-based, prepectoral breast reconstruction after mastectomy. Patients who underwent implant-based, prepectoral breast reconstruction between 2019 and 2022 were reviewed. Groups were divided into those who received antibiotic beads and those who did not. Outcome variables included postoperative infection at 90 days. A total of 148 patients (256 implants) were included: 15 patients (31 implants) who received biodegradable antibiotic beads and 133 patients (225 implants) in the control group. Patients who received antibiotic beads were more likely to have a history of infection (66.7%) compared with the control group (0%) (P < 0.01). Surgical site infection occurred in 3.2% of implants in the antibiotic bead group compared with 7.6%, but this did not reach statistical significance. The incidence of infection in high-risk patients who have absorbable antibiotic beads placed during the time of reconstruction seems to be normalized to the control group in this pilot study. We present a novel use of prophylactic absorbable antibiotic beads in prepectoral breast implant reconstruction.

β-Cell Cre Expression and Reduced Ins1 Gene Dosage Protect Mice From Type 1 Diabetes

A central goal of physiological research is the understanding of cell-specific roles of disease-associated genes. Cre-mediated recombineering is the tool of choice for cell type-specific analysis of gene function in preclinical models. In the type 1 diabetes (T1D) research field, multiple lines of nonobese diabetic (NOD) mice have been engineered to express Cre recombinase in pancreatic β cells using insulin promoter fragments, but tissue promiscuity remains a concern. Constitutive Ins1tm1.1(cre)Thor (Ins1Cre) mice on the C57/bl6-J background have high β-cell specificity with no reported off-target effects. We explored whether NOD:Ins1Cre mice could be used to investigate β-cell gene deletion in T1D disease modeling. We studied wild-type (Ins1WT/WT), Ins1 heterozygous (Ins1Cre/WT or Ins1Neo/WT), and Ins1 null (Ins1Cre/Neo) littermates on a NOD background. Female Ins1Neo/WT mice exhibited significant protection from diabetes, with further near-complete protection in Ins1Cre/WT mice. The effects of combined neomycin and Cre knockin in Ins1Neo/Cre mice were not additive to the Cre knockin alone. In Ins1Neo/Cre mice, protection from diabetes was associated with reduced insulitis at age 12 weeks. Collectively, these data confirm previous reports that loss of Ins1 alleles protects NOD mice from diabetes development and demonstrates, for the first time, that Cre itself may have additional protective effects. This has important implications for the experimental design and interpretation of preclinical T1D studies using β-cell-selective Cre in NOD mice.

US medical student perspectives on asian american patient inclusion in medical education: a qualitative Study

BACKGROUND

Asian American (AsAm) representation is lacking in conversations surrounding cultural humility in healthcare. We aimed to investigate US medical student perspectives on AsAm patient inclusion in cultural humility training in medical education.

METHODS

This qualitative study analyzed free-text responses to an optional, open-ended question presented at the conclusion of an online survey assessing medical student experiences with and perceptions regarding AsAm patients in their medical education. This survey was distributed to a convenience sample of nine US medical schools. Medical students who completed at least one clinical rotation were eligible to participate in the survey. Qualitative analysis of free-text responses was conducted in an iterative process to generate emergent themes.

RESULTS

There was a total of 195 optional free-text responses from 688 participants (28%). Motivation to learn about AsAm population included shared identity and desire to better serve the AsAm population in their local community and future careers. Topics of interest included healthcare-related cultural preferences, healthcare delivery strategies, and health disparities for the AsAm population and other minority patients. Students reported that they drew on personal experiences and some pre-clinical or clinical exposures to learn about AsAm patients. Respondents cited the lack of exposure in the medical school curriculum and clinical experiences as the main challenge to learning about AsAm health and provided suggestions for the delivery of this education in their pre-clinical and clinical education. Respondents emphasized that AsAms are treated as a monolith in medical education and healthcare, despite their heterogeneity.

CONCLUSIONS

Medical students identified a need and interest for greater inclusion of AsAm topics in medical education on cultural humility and minority health.

Knowledge and attitudes of U.S. medical students regarding the care of Asian American patients: a cross-sectional survey study

BACKGROUND

Asian Americans (AsAm) are a rapidly growing population in the U.S. With this growing population, U.S. healthcare providers must be equipped to provide culturally competent care for AsAm patients. This project surveyed U.S. medical students on their knowledge of and attitudes towards AsAm to assess predictors of readiness to care for AsAm patients.

METHOD

This cross-sectional study surveyed medical students who had completed at least one clinical rotation. The survey was distributed online to nine medical schools throughout the U.S. The survey measured self-rated knowledge of, comfort with, cultural competency (CC) towards, and explicit biases towards AsAm patients. The first three domains were analyzed in a multivariate regression model including sociodemographic characteristics and past clinical, curricular, and social experiences with AsAm. Explicit bias questions were reported descriptively.

RESULTS

There were 688 respondents. Asian race, AsAm-prevalent hometown, AsAm-related extracurricular activities, Asian language knowledge, and having taken a population health course predicted increased AsAm knowledge. Social interactions with AsAm increased comfort with AsAm patients. Increasing year in medical school, more frequent exposure to AsAm patients on rotations, and prior travel to an Asian country were predictors of increased CC toward AsAm. Importantly, having completed a CC course was a significant predictor in all domains. In terms of explicit bias, students felt that AsAm patients were more compliant than Caucasian patients. Students also believed that Caucasian patients were generally more likely to receive self-perceived "preferred" versus "acceptable" care, but that in their own clinical experiences neither group received preferred care.

CONCLUSION

Experience with and exposure to AsAm prior to and during medical school and CC courses may increase medical student knowledge, comfort, and CC with AsAm patients. Standardized and longitudinal CC training, increased simulations with AsAm patients, diverse student recruitment, and support for students to engage in AsAm-related activities and interact with AsAm may improve CC of future physicians towards AsAm patients and possibly other minority populations.

UV-inactivated HSV-1 potently activates NK cell killing of leukemic cells

Herein we demonstrate that oncolytic herpes simplex virus-1 (HSV-1) potently activates human peripheral blood mononuclear cells (PBMCs) to lyse leukemic cell lines and primary acute myeloid leukemia samples, but not healthy allogeneic lymphocytes. Intriguingly, we found that UV light-inactivated HSV-1 (UV-HSV-1) is equally effective in promoting PBMC cytolysis of leukemic cells and is 1000- to 10 000-fold more potent at stimulating innate antileukemic responses than UV-inactivated cytomegalovirus, vesicular stomatitis virus, reovirus, or adenovirus. Mechanistically, UV-HSV-1 stimulates PBMC cytolysis of leukemic cells, partly via Toll-like receptor-2/protein kinase C/nuclear factor-κB signaling, and potently stimulates expression of CD69, degranulation, migration, and cytokine production in natural killer (NK) cells, suggesting that surface components of UV-HSV-1 directly activate NK cells. Importantly, UV-HSV-1 synergizes with interleukin-15 (IL-15) and IL-2 in inducing activation and cytolytic activity of NK cells. Additionally, UV-HSV-1 stimulates glycolysis and fatty acid oxidation-dependent oxygen consumption in NK cells, but only glycolysis is required for their enhanced antileukemic activity. Last, we demonstrate that T cell-depleted human PBMCs exposed to UV-HSV-1 provide a survival benefit in a murine xenograft model of human acute myeloid leukemia (AML). Taken together, our results support the preclinical development of UV-HSV-1 as an adjuvant, alone or in combination with IL-15, for allogeneic donor mononuclear cell infusions to treat AML.

Reduced Insulin Production Relieves Endoplasmic Reticulum Stress and Induces β Cell Proliferation

Pancreatic β cells are mostly post-mitotic, but it is unclear what locks them in this state. Perturbations including uncontrolled hyperglycemia can drive β cells into more pliable states with reduced cellular insulin levels, increased β cell proliferation, and hormone mis-expression, but it is unknown whether reduced insulin production itself plays a role. Here, we define the effects of ∼50% reduced insulin production in Ins1(-/-):Ins2(f/f):Pdx1Cre(ERT):mTmG mice prior to robust hyperglycemia. Transcriptome, proteome, and network analysis revealed alleviation of chronic endoplasmic reticulum (ER) stress, indicated by reduced Ddit3, Trib3, and Atf4 expression; reduced Xbp1 splicing; and reduced phospho-eIF2α. This state was associated with hyper-phosphorylation of Akt, which is negatively regulated by Trib3, and with cyclinD1 upregulation. Remarkably, β cell proliferation was increased 2-fold after reduced insulin production independently of hyperglycemia. Eventually, recombined cells mis-expressed glucagon in the hyperglycemic state. We conclude that the normally high rate of insulin production suppresses β cell proliferation in a cell-autonomous manner.

High-content screening identifies a role for Na(+) channels in insulin production

Insulin production is the central feature of functionally mature and differentiated pancreatic β-cells. Reduced insulin transcription and dedifferentiation have been implicated in type 2 diabetes, making drugs that could reverse these processes potentially useful. We have previously established ratiometric live-cell imaging tools to identify factors that increase insulin promoter activity and promote β-cell differentiation. Here, we present a single vector imaging tool with eGFP and mRFP, driven by the Pdx1 and Ins1 promoters, respectively, targeted to the nucleus to enhance identification of individual cells in a high-throughput manner. Using this new approach, we screened 1120 off-patent drugs for factors that regulate Ins1 and Pdx1 promoter activity in MIN6 β-cells. We identified a number of compounds that positively modulate Ins1 promoter activity, including several drugs known to modulate ion channels. Carbamazepine was selected for extended follow-up, as our previous screen also identified this use-dependent sodium channel inhibitor as a positive modulator of β-cell survival. Indeed, carbamazepine increased Ins1 and Ins2 mRNA in primary mouse islets at lower doses than were required to protect β-cells. We validated the role of sodium channels in insulin production by examining Nav1.7 (Scn9a) knockout mice and remarkably islets from these animals had dramatically elevated insulin content relative to wild-type controls. Collectively, our experiments provide a starting point for additional studies aimed to identify drugs and molecular pathways that control insulin production and β-cell differentiation status. In particular, our unbiased screen identified a novel role for a β-cell sodium channel gene in insulin production.

14-3-3ζ coordinates adipogenesis of visceral fat

The proteins that coordinate complex adipogenic transcriptional networks are poorly understood. 14-3-3ζ is a molecular adaptor protein that regulates insulin signalling and transcription factor networks. Here we report that 14-3-3ζ-knockout mice are strikingly lean from birth with specific reductions in visceral fat depots. Conversely, transgenic 14-3-3ζ overexpression potentiates obesity, without exacerbating metabolic complications. Only the 14-3-3ζ isoform is essential for adipogenesis based on isoform-specific RNAi. Mechanistic studies show that 14-3-3ζ depletion promotes autophagy-dependent degradation of C/EBP-δ, preventing induction of the master adipogenic factors, Pparγ and C/EBP-α. Transcriptomic data indicate that 14-3-3ζ acts upstream of hedgehog signalling-dependent upregulation of Cdkn1b/p27(Kip1). Indeed, concomitant knockdown of p27(Kip1) or Gli3 rescues the early block in adipogenesis induced by 14-3-3ζ knockdown in vitro. Adipocyte precursors in 14-3-3ζKO embryos also appear to have greater Gli3 and p27(Kip1) abundance. Together, our in vivo and in vitro findings demonstrate that 14-3-3ζ is a critical upstream driver of adipogenesis.

Effect of different casting methods on adolescent idiopathic scoliosis

Scoliosis is a three-dimensional spinal deformity. Although orthotic treatment for moderate adolescent idiopathic scoliosis (AIS) has been well recognized, there are few studies documenting the effectiveness of different casting methods in the fabrication of thoracolumbo-sacral orthoses (TLSO). The current study was a retrospective clinical evaluation of the effectiveness of two commonly used casting methods namely, the frame casting method and the supine with traction casting method in the treatment of AIS. Eighty (80) female patients with AIS were recruited and they were all treated by TLSOs. The frame casting method was used in 37 patients while the remaining 43 patients were under the supine with traction casting method. The responses of spinal deformities under the two different casting methods were analyzed for the period from pre-brace to 2 years after bracing. The studied parameters included the AP Cobb's angle, the apical vertebral rotation and the trunk listing (cervico-sacral lateral offset). The results of the current study showed that the orthoses manufactured from the two casting methods could provide an effective control of AIS (change of Cobb's angle within (+/- 5 degrees). For the frame casting, the Cobb's angles at pre-brace and 2 years after off-brace were 36.0 degrees and 33.8 degrees respectively while for the supine with traction casting, the corresponding Cobb's angles were 32.7 degrees and 34.0 degrees. The frame casting method could give a better control of the apical vertebral rotation at the early stage of treatment (pre-brace = 18.2 degrees and the 4th month = 13.8 degrees while the supine with traction casting method was more effective in the long-term control of the trunk listing (pre-brace = 10mm and 2 years after off-brace = 3.3mm).