Understanding the physical interactions in the FGF21/FGFR/β-Klotho complex: structural requirements and implications in FGF21 signaling

The endocrine fibroblast growth factor 21 (FGF21) requires both fibroblast growth factor receptor (FGFR) and β-Klotho for signaling. In this study, we sought to understand the inter-molecular physical interactions in the FGF21/FGFR/β-Klotho complex by deleting key regions in FGFR1c or FGF21. Deletion of the D1 and the D1-D2 linker (the D1/linker region) from FGFR1c led to β-Klotho-independent receptor activation by FGF21, suggesting that there may be a direct interaction between FGF21 and the D1/linker region-deficient FGFR1c. Consistent with this, the extracellular portion of FGFR1c lacking the D1/linker region blocked FGF21 action in a reporter assay, presumably by binding to and sequestering FGF21 from acting on cell surface receptor complex. In addition, the D1/linker region-deficient FGFR1c had enhanced interaction with β-Klotho. Further, we demonstrated that deletion of the D1/linker region enhanced the formation of the FGF21/β-Klotho/FGFR1c ternary complex in both Biacore and asymmetrical flow field flow fractionation studies. Finally, we found that the N-terminus of FGF21 is involved in the interaction with FGFR1c and FGF21/β-Klotho/FGFR1c ternary complex formation. Taken together, our data suggest that the D1/linker region regulates both the FGF21/FGFR1c and FGFR1c/β-Klotho interaction, and a direct interaction of FGF21 with FGFR1c may be an important step in receptor-mediated FGF21 signaling.     

Genome-wide association study identifies new prostate cancer susceptibility loci

Prostate cancer (PrCa) is the most common non-skin cancer diagnosed among males in developed countries and the second leading cause of cancer mortality, yet little is known regarding its etiology and factors that influence clinical outcome. Genome-wide association studies (GWAS) of PrCa have identified at least 30 distinct loci associated with small differences in risk. We conducted a GWAS in 2782 advanced PrCa cases (Gleason grade ≥ 8 or tumor stage C/D) and 4458 controls with 571 243 single nucleotide polymorphisms (SNPs). Based on in silico replication of 4679 SNPs (Stage 1, P < 0.02) in two published GWAS with 7358 PrCa cases and 6732 controls, we identified a new susceptibility locus associated with overall PrCa risk at 2q37.3 (rs2292884, P= 4.3 × 10(-8)). We also confirmed a locus suggested by an earlier GWAS at 12q13 (rs902774, P= 8.6 × 10(-9)). The estimated per-allele odds ratios for these loci (1.14 for rs2292884 and 1.17 for rs902774) did not differ between advanced and non-advanced PrCa (case-only test for heterogeneity P= 0.72 and P= 0.61, respectively). Further studies will be needed to assess whether these or other loci are differentially associated with PrCa subtypes.     

Maternal stress during pregnancy causes sex-specific alterations in offspring memory performance, social interactions, indices of anxiety, and body mass

Prenatal stress (PS) impairs memory function; however, it is not clear whether PS-induced memory deficits are specific to spatial memory, or whether memory is more generally compromised by PS. Here we sought to distinguish between these possibilities by assessing spatial, recognition and contextual memory functions in PS and nonstressed (NS) rodents. We also measured anxiety-related and social behaviors to determine whether our unpredictable PS paradigm generates a behavioral phenotype comparable to previous studies. Female Sprague-Dawley rats were exposed to daily random stress during the last gestational week and behavior tested in adulthood. In males but not females, PS decreased memory for novel objects and novel spatial locations, and facilitated memory for novel object/context pairings. In the elevated zero maze, PS increased anxiety-related behavior only in females. Social behaviors also varied with sex and PS condition. Females showed more anogenital sniffing regardless of stress condition. In contrast, prenatal stress eliminated a male-biased sex difference in nonspecific bodily sniffing by decreasing sniffing in males, and increasing sniffing in females. Finally, PS males but not females gained significantly more weight across adulthood than did NS controls. In summary, these data indicate that PS differentially impacts males and females resulting in sex-specific adult behavioral and bodily phenotypes.     

Impaired memory CD8 T cell responses against an immunodominant retroviral cryptic epitope

The immunodominant cryptic epitope SYNTGRFPPL, encoded within open reading frame 2 of the LP-BM5 retroviral gag gene, is critical for protection against retroviral-induced pathogenesis. The goal of this study was to dissect the memory response against this unique immunodominant cryptic epitope. Unlike the protective acute effector population of SYNTGRFPPL-specific CD8 T cells, long-lived SYNTGRFPPL-specific CD8 T cells lacked the ability to protect susceptible mice infected with LP-BM5 retrovirus. Compared to memory CD8 T cells against a conventional epitope with similar MHC-I specificity, primed and restimulated using similar conditions, long-lived SYNTGRFPPL-specific CD8 T cells were impaired in their ability to recall against antigen, with reduced cytolytic capabilities and cytokine production. Since similar priming and restimulation regimes were utilized to generate each effector CD8 T cell population, this study has potentially broad implications with regard to the selection criteria of potent, highly conserved cryptic epitopes for use in epitope-based vaccines.     

Receptor specificity of subtype H1 influenza A viruses isolated from swine and humans in the United States

The evolution of classical swine influenza viruses receptor specificity preceding the emergence of the 2009 H1N1 pandemic virus was analyzed in glycan microarrays. Classical swine influenza viruses from the α, β, and γ antigenic clusters isolated between 1945 and 2009 revealed a binding profile very similar to that of 2009 pandemic H1N1 viruses, with selectivity for α2-6-linked sialosides and very limited binding to α2-3 sialosides. Despite considerable genetic divergence, the ‘human-like’ H1N1 viruses circulating in swine retained strong binding preference for α2-6 sialylated glycans. Interspecies transmission of H1N1 influenza viruses from swine to humans or from humans to swine has not driven selection of viruses with distinct novel receptor binding specificities. Classical swine and human seasonal H1N1 influenza viruses have conserved specificity for similar α2-6-sialoside receptors in spite of long term circulation in separate hosts, suggesting that humans and swine impose analogous selection pressures on the evolution of receptor binding function.     

Dried culture spots for Xpert MTB/RIF external quality assessment: results of a phase 1 pilot study in South Africa

Implementation of Xpert MTB/RIF requires quality assessment. A pilot program using dried culture spots (DCSs) of inactivated Mycobacterium tuberculosis is described. Of 274 DCS results received, 2.19% generated errors; the remainder yielded 100% correct Mycobacterium tuberculosis detection. The probe A cycle threshold (C(T)) variability of three DCS batches was ≤ 3.47. The study of longer-term DCS stability is ongoing.     

The Importance of Early Carotid Endarterectomy in Symptomatic Patients

INTRODUCTION

Early carotid endarterectomy (CEA) in symptomatic patients may prevent repeat cerebral events. This study investigates the relationship between waiting time for CEA and the incidence of repeat cerebral events prior to surgery in symptomatic patients.

PATIENTS AND METHODS

A prospective database of consecutive patients undergoing CEA between January 2002 and December 2006 was reviewed. Repeat event rates prior to surgery were calculated using Kaplan–Meier analysis and predictive factors identified using Cox regression analysis.

RESULTS

A total of 118 patients underwent CEA for non-disabling stroke, TIA and amaurosis fugax. Repeat cerebral events occurred in 34 of 118 (29%) patients at a median 51 days (range, 2–360 days) after the first event. The estimated risk of repeat events was 2% at 7 days and 9% at 1 month after first event (Kaplan–Meier survival analysis). Age (HR 1.059; 95% CI 1.014–1.106; P = 0.009] was identified as a predictor of repeat events. Patients underwent surgery at median 97 days (range, 7–621 days) after the first event. Eleven of 60 (18%) patients waiting ≤?97 days for surgery and 23 of 58 (40%) patients waiting >?97 days had repeat events. (P = 0.011, chi-squared test).

CONCLUSIONS

Delays in surgery should be reduced in order to minimise repeat cerebral events in patients with symptomatic carotid stenosis, particularly in the elderly population.     

Measuring Electronic Health Record Use in the Pediatric ICU Using Audit-Logs and Screen Recordings

Background  Time spent in the electronic health record (EHR) has been identified as an important unit of measure for health care provider clinical activity. The lack of validation of audit-log based inpatient EHR time may have resulted in underuse of this data in studies focusing on inpatient patient outcomes, provider efficiency, provider satisfaction, etc. This has also led to a dearth of clinically relevant EHR usage metrics consistent with inpatient provider clinical activity. Objective  The aim of our study was to validate audit-log based EHR times using observed EHR-times extracted from screen recordings of EHR usage in the inpatient setting. Methods  This study was conducted in a 36-bed pediatric intensive care unit (PICU) at Lucile Packard Children''s Hospital Stanford between June 11 and July 14, 2020. Attending physicians, fellow physicians, hospitalists, and advanced practice providers with ≥0.5 full-time equivalent (FTE) for the prior four consecutive weeks and at least one EHR session recording were included in the study. Citrix session recording player was used to retrospectively review EHR session recordings that were captured as the provider interacted with the EHR. Results  EHR use patterns varied by provider type. Audit-log based total EHR time correlated strongly with both observed total EHR time ( r  = 0.98, p  < 0.001) and observed active EHR time ( r  = 0.95, p  < 0.001). Each minute of audit-log based total EHR time corresponded to 0.95 (0.87–1.02) minutes of observed total EHR time and 0.75 (0.67–0.83) minutes of observed active EHR time. Results were similar when stratified by provider role. Conclusion  Our study found inpatient audit-log based EHR time to correlate strongly with observed EHR time among pediatric critical care providers. These findings support the use of audit-log based EHR-time as a surrogate measure for inpatient provider EHR use, providing an opportunity for researchers and other stakeholders to leverage EHR audit-log data in measuring clinical activity and tracking outcomes of workflow improvement efforts longitudinally and across provider groups.