Racial and Ethnic Differences in Inpatient Palliative Care for Pediatric Stem Cell Transplant Patients.

OBJECTIVES: Racial/ethnic disparities in utilizing inpatient palliative care services are well documented in the adult literature. However, the impact of racial/ethnic disparities in the context of pediatric palliative care is less well understood even in high-acuity patient populations such as stem cell transplant patients. We investigated racial/ethnic differences in the utilization of inpatient palliative care consultations (IPCCs) for pediatric stem cell transplant patients. STUDY DESIGN: A retrospective cohort study was conducted using the Pediatric Health Information System database. A generalized linear mixed effects model was developed to assess demographic and clinical characteristics associated with the likelihood of receiving IPCC. SETTING: Thirty-eight tertiary pediatric hospitals in the United States. PATIENTS: Pediatric patients undergoing stem cell transplantation for any indication from January 2017 to December 2019. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of the 1,193 inpatient encounters studied, 12% (n = 143) included a palliative care consult. IPCC rates varied across hospitals with a median rate of 5.97% (interquartile range, 0.00-20.71). In multivariable analyses, Hispanic/Latinx patients were 59% less likely to receive IPCC compared with non-Hispanic White patients (odds ratio [OR], 0.41; 95% CI, 0.21-0.78). This difference persisted after adjusting for all other sociodemographic and clinical factors. In terms of the other clinical characteristics, having a malignant condition and mechanical ventilation were associated with significantly increased odds of receiving IPCC for the entire cohort (OR Malignancy: 1.93; 95% CI: 1.07-3.51; OR Mechanical Ventilation: 2.37; 95% CI: 1.36-4.13). The remainder of the variables were not found to be significantly associated with IPCC. CONCLUSIONS: Racial and ethnic differences exist in the likelihood of receiving palliative care consultations among hospitalized pediatric stem cell transplant recipients. Evaluating the impact of systemic racism and social determinants on palliative care medicine as well as standardizing early integration of IPCC may potentially mitigate disparities in this population.

Outpatient Management of Febrile Children With Sickle Cell Disease.

The electronic medical records at 2 children's hospitals were reviewed from June 1, 2011 to May 31, 2013 for all patients with sickle cell disease who presented with fever. Of a total of 390 blood cultures drawn, 11 cultures (2.8%) turned positive with only 1 (0.3%) growing a true pathogen. This culture turned positive in 13 hours. There were 154 patients who received exclusive outpatient management of fever. Fourteen patients (9.1%) completed 1 acute care visit, 16 patients (10.4%) completed 2 acute care visits, and 124 patients (80.5%) completed 3 acute care visits. Of those treated exclusively as outpatients, there was 1 positive culture that was considered a contaminant. Although the overall rate of positivity was low, this study confirms previous findings that pediatric blood cultures become positive with pathogens within 48 hours. Given the high rate of compliance and early time to positivity of true pathogens, we suggest that follow-up for the febrile sickle cell disease patients can be treated on an outpatient basis.

Osteitis fibrosa is mediated by Platelet-Derived Growth Factor-A via a phosphoinositide 3-kinase-dependent signaling pathway in a rat model for chronic hyperparathyroidism.

Abnormal secretion of PTH by the parathyroid glands contributes to a variety of common skeletal disorders. Prior studies implicate platelet-derived growth factor-A (PDGF-A) as an important mediator of selective PTH actions on bone. The present studies used targeted gene profiling and small-molecule antagonists directed against candidate gene products to elucidate the roles of specific PTH-regulated genes and signaling pathways. A group of 29 genes in rats continuously infused with PTH and cotreated with the PDGF receptor antagonist trapidil were differentially expressed compared with PTH treatment alone. Several of the identified genes were functionally clustered as regulators of fibroblast differentiation and extracellular matrix modeling, including the matrix cross-linking enzyme lysyl oxidase (LOX). Treatment with beta-aminopropionitrile, an irreversible inhibitor of LOX activity, dramatically reduced diffuse mineralization but had no effect on PTH-induced fibrosis. In contrast, the receptor tyrosine kinase inhibitor Gleevec and the phosphoinositide 3-kinase inhibitor wortmannin each reduced bone marrow fibrosis. In summary, the present studies support the hypotheses that PTH-induced bone marrow fibrosis is mediated by PDGF-A via a phosphoinositide 3-kinase-dependent signaling pathway and that increased LOX gene expression plays a key role in abnormal mineralization, a hallmark of chronic hyperparathyroidism.

Truncation of the C-terminus of human MLH1 blocks intracellular stabilization of PMS2 and disrupts DNA mismatch repair.

The human DNA mismatch repair (MMR) protein MLH1 has essential roles in the correction of replication errors and the activation of cell cycle checkpoints and cytotoxic responses to DNA damage that contribute to suppression of cancer risk. MLH1 functions as a heterodimer with the PMS2 protein, and steady state levels of PMS2 are very low in MLH1-deficient cells. Unique to MLH1 among MutL-homolog proteins, and conserved in identified eukaryotic MLH1 proteins, is the so-called C-terminal homology domain (CTH). The function of these C-terminal 20-30 amino acids is not known. We investigated the effect of a C-terminal truncation of human MLH1 (MLH1-L749X) on mammalian MMR by testing its activity in MLH1-deficient cells. We found the CTH to be essential for suppression of spontaneous mutation, activation of a cytotoxic response to 6-thioguanine, and maintenance of normal steady state levels of PMS2. Co-expression in doubly mutant Mlh1-/-; Pms2-/- fibroblasts showed that MLH1-L749X was unable to stabilize PMS2. Over-expression of MLH1-L749X did not reduce stabilization of PMS2 mediated by wild-type MLH1, indicating that truncation of the CTH reduces the ability to compete with wild-type MLH1 for interaction with PMS2. Lack of PMS2 stabilization also was observed with a previously reported pathogenic truncation (MLH1-Y750X), but not with two different point mutations in the CTH. Biochemical assays demonstrated that truncation of the CTH reduced the stability of heterodimers, although MLH1-L749X retained significant capacity for interaction with PMS2. Thus, the CTH of human MLH1 is necessary for error correction, checkpoint signaling, and for promoting interaction with, and the stability of, PMS2. Analysis of the CTH role in stabilizing PMS2 was facilitated by a novel intracellular assay for MLH1-PMS2 interaction. This assay should prove useful for identifying additional amino acids in MLH1 and PMS2 necessary for interaction in cells, and for determining the functional consequences of MLH1 mutations identified in human cancers.