Faculty Bibliography

To investigate the effects and mechanisms of irisin, a newly discovered myokine, in cartilage development, osteoarthritis (OA) pathophysiology and its therapeutic potential for treating OA we applied the following five strategical analyses using (1) murine joint tissues at different developmental stages; (2) human normal and OA pathological tissue samples; (3) experimental OA mouse model; (4) irisin gene knockout (KO) and knock in (KI) mouse lines and their cartilage cells; (5) in vitro mechanistic experiments. We found that Irisin was involved in all stages of cartilage development. Both human and mouse OA tissues showed a decreased expression of irisin. Intra-articular injection of irisin attenuated ACLT-induced OA progression. Irisin knockout mice developed severe OA while irisin overexpression in both irisin KI mice and intraarticular injection of irisin protein attenuated OA progression. Irisin inhibited inflammation and promoted anabolism in chondrogenic ADTC5 cells. Proliferative potential of primary chondrocytes from KI mice was found to be enhanced, while KO mice showed an inhibition under normal or inflammatory conditions. The primary chondrocytes from irisin KI mice showed reduced expression of inflammatory factors and the chondrocytes isolated from KO mice showed an opposite pattern. In conclusion, it is the first time to show that irisin is involved in cartilage development and OA pathogenesis. Irisin has the potential to ameliorate OA progression by decreasing cartilage degradation and inhibiting inflammation, which could lead to the development of a novel therapeutic target for treating bone and cartilage disorders including osteoarthritis.

BACKGROUND:Limited research has addressed the obesity-COVID-19 severity association in paediatric patients. OBJECTIVE:To determine whether obesity is an independent risk factor for COVID-19 severity in paediatric patients and whether age modifies this association. METHODS:SARS-CoV-2-positive patients at NYU Langone Health from 1 March 2020 to 3 January 2021 aged 0-21 years with available anthropometric measurements: weight, length/height and/or body mass index (BMI). Modified log-Poisson models were utilized for the analysis. Main outcomes were 1) hospitalization and 2) critical illness (intensive care unit [ICU] admission). RESULTS:One hundred and fifteen of four hundred and ninety-four (23.3%) patients had obesity. Obesity was an independent risk factor for critical illness (adjusted risk ratio [ARR] 2.02, 95% CI 1.17 to 3.48). This association was modified by age, with obesity related to a greater risk for critical illness in adolescents (13-21 years) [ARR 3.09, 95% CI 1.48 to 6.47], but not in children (0-12 years). Obesity was not an independent risk factor for hospitalization for any age. CONCLUSION/CONCLUSIONS:Obesity was an independent risk factor for critical illness in paediatric patients, and this association was modified by age, with obesity related to a greater risk for critical illness in adolescents, but not in children. These findings are crucial for patient risk stratification and care.

Parthenogenetic embryos, created by activation and diploidization of oocytes, arrest at mid-gestation for defective paternal imprints, which impair placental development. Also, viable offspring has not been obtained without genetic manipulation from parthenogenetic embryonic stem cells (pESCs) derived from parthenogenetic embryos, presumably attributable to their aberrant imprinting. We show that an unlimited number of oocytes can be derived from pESCs and produce healthy offspring. Moreover, normal expression of imprinted genes is found in the germ cells and the mice. pESCs exhibited imprinting consistent with exclusively maternal lineage, and higher X-chromosome activation compared to female ESCs derived from the same mouse genetic background. pESCs differentiated into primordial germ cell-like cells (PGCLCs) and formed oocytes following in vivo transplantation into kidney capsule that produced fertile pups and reconstituted ovarian endocrine function. The transcriptome and methylation of imprinted and X-linked genes in pESC-PGCLCs closely resembled those of in vivo produced PGCs, consistent with efficient reprogramming of methylation and genomic imprinting. These results demonstrate that amplification of germ cells through parthenogenesis faithfully maintains maternal imprinting, offering a promising route for deriving functional oocytes and having potential in rebuilding ovarian endocrine function.

Zebrafish provide an excellent model for in vivo cell biology studies because of their amenability to live imaging. Protein visualization in zebrafish has traditionally relied on overexpression of fluorescently tagged proteins from heterologous promoters, making it difficult to recapitulate endogenous expression patterns and protein function. One way to circumvent this problem is to tag the proteins by modifying their endogenous genomic loci. Such an approach is not widely available to zebrafish researchers because of inefficient homologous recombination and the error-prone nature of targeted integration in zebrafish. Here, we report a simple approach for tagging proteins in zebrafish on their N or C termini with fluorescent proteins by inserting PCR-generated donor amplicons into non-coding regions of the corresponding genes. Using this approach, we generated endogenously tagged alleles for several genes that are crucial for epithelial biology and organ development, including the tight junction components ZO-1 and Cldn15la, the trafficking effector Rab11a, the apical polarity protein aPKC and the ECM receptor Integrin β1b. Our approach facilitates the generation of knock-in lines in zebrafish, opening the way for accurate quantitative imaging studies.

Although distal radius fractures are quite common, bilateral distal radius fractures seldomly occur. Due to this, treatment is primarily based on surgeon experience with unilateral fractures, however bi- lateral fractures add a level of complexity : loss of functional independence. The purpose of this study was to examine a cohort of patients with bilateral distal radius fractures to identify differences in demographics, mechanism of injury, and outcomes to further our understanding of these rare injuries. 23 patients were identified retrospectively over a 5-year period that met inclusion criteria. The medical records were reviewed with multiple demographic and clinical parameters recorded and analyzed. Males were more likely to sustain high-energy mechanisms (80% vs. 53%). Patients <50 years old were more likely to sustain high-energy mechanisms (90% vs. 46%) and were more likely to be treated operatively (80% vs. 62%). The most commonly associated injury was a head injury (30%). All patients treated non-operatively reported minimal/no pain upon final follow-up where 57% of patients treated operatively noted regular pain. 75% of patients with medical comorbidities had minimal/no pain upon final follow- up. Conclusions : Patients with bilateral fractures were more likely to be younger males who suffered from higher energy mechanisms. Age was a critical factor in determining treatment strategy. Rates of associated head injuries were elevated, which is an important factor for the clinician to keep in mind when treating this population. As we further our understanding of this unique population, we can improve our treatment approaches and subsequently attain better outcomes.

Cancer cell plasticity due to the dynamic architecture of interactome networks provides a vexing outlet for therapy evasion. Here, through chemical biology approaches for systems level exploration of protein connectivity changes applied to pancreatic cancer cell lines, patient biospecimens, and cell- and patient-derived xenografts in mice, we demonstrate interactomes can be re-engineered for vulnerability. By manipulating epichaperomes pharmacologically, we control and anticipate how thousands of proteins interact in real-time within tumours. Further, we can essentially force tumours into interactome hyperconnectivity and maximal protein-protein interaction capacity, a state whereby no rebound pathways can be deployed and where alternative signalling is supressed. This approach therefore primes interactomes to enhance vulnerability and improve treatment efficacy, enabling therapeutics with traditionally poor performance to become highly efficacious. These findings provide proof-of-principle for a paradigm to overcome drug resistance through pharmacologic manipulation of proteome-wide protein-protein interaction networks.

Organ function relies on the spatial organization and functional coordination of numerous cell types. The Drosophila ovary is a widely used model system to study the cellular activities underlying organ function, including stem cell regulation, cell signaling and epithelial morphogenesis. However, the relative paucity of cell type-specific reagents hinders investigation of molecular functions at the appropriate cellular resolution. Here, we used single-cell RNA sequencing to characterize all cell types of the stem cell compartment and early follicles of the Drosophila ovary. We computed transcriptional signatures and identified specific markers for nine states of germ cell differentiation and 23 somatic cell types and subtypes. We uncovered an unanticipated diversity of escort cells, the somatic cells that directly interact with differentiating germline cysts. Three escort cell subtypes reside in discrete anatomical positions and express distinct sets of secreted and transmembrane proteins, suggesting that diverse micro-environments support the progressive differentiation of germ cells. Finally, we identified 17 follicle cell subtypes and characterized their transcriptional profiles. Altogether, we provide a comprehensive resource of gene expression, cell type-specific markers, spatial coordinates, and functional predictions for 34 ovarian cell types and subtypes.

The field of cardio-oncology has emerged in response to the increased risk of cardiovascular disease (CVD) in patients with cancer. However, recent studies suggest a more complicated CVD-cancer relationship, wherein development of CVD, either prior to or following a cancer diagnosis, can also lead to increased risk of cancer and worse outcomes for patients. In this review, we describe the current evidence base, across epidemiological as well as preclinical studies, which supports the emerging concept of 'reverse-cardio oncology', or CVD-induced acceleration of cancer pathogenesis.

AIMS/OBJECTIVE:Physician burnout and its consequences have been recognized as increasingly prevalent and important issues for both organizations and individuals involved in healthcare delivery. The purpose of this study was to describe and compare the patterns of self-reported wellness in orthopaedic surgeons and trainees from multiple nations with varying health systems. METHODS:A cross-sectional survey of 774 orthopaedic surgeons and trainees in five countries (Australia, Canada, New Zealand, UK, and USA) was conducted in 2019. Respondents were asked to complete the Mayo Clinic Well-Being Index and the Stanford Professional Fulfillment Index in addition to 31 personal/demographic questions and 27 employment-related questions via an anonymous online survey. RESULTS:A total of 684 participants from five countries (Australia (n = 74), Canada (n = 90), New Zealand (n = 69), UK (n = 105), and USA (n = 346)) completed both of the risk assessment questionnaires (Mayo and Stanford). Of these, 42.8% (n = 293) were trainees and 57.2% (n = 391) were attending surgeons. On the Mayo Clinic Well-Being Index, 58.6% of the overall sample reported feeling burned out (n = 401). Significant differences were found between nations with regards to the proportion categorized as being at risk for poor outcomes (27.5% for New Zealand (19/69) vs 54.4% for Canada (49/90) ; p = 0.001). On the Stanford Professional Fulfillment Index, 38.9% of the respondents were classified as being burned out (266/684). Prevalence of burnout ranged from 27% for Australia (20/74 up to 47.8% for Canadian respondents (43/90; p = 0.010). Younger age groups (20 to 29: RR 2.52 (95% confidence interval (CI) 1.39 to 4.58; p = 0.002); 30 to 39: RR 2.40 (95% CI 1.36 to 4.24; p = 0.003); 40 to 49: RR 2.30 (95% CI 1.35 to 3.9; p = 0.002)) and trainee status (RR 1.53 (95% CI 1.15 to 2.03 p = 0.004)) were independently associated with increased relative risk of having a 'at-risk' or 'burnout' score. CONCLUSIONS: 2021;2(11):932-939.