RESUMO
BACKGROUND: Both endoplasmic reticulum (ER) stress and autophagy have been shown to display dual roles in cell survival in multiple cell lines. There is a reported but poorly understood link between ER stress, autophagy, and cell death. We hypothesized that autophagy plays a role in ER stress-dependent cell death in rat hepatocytes. MATERIALS AND METHODS: Primary hepatocytes isolated from both lean and obese male Zucker rats were cultured and treated with tunicamycin (TM), tauroursodeoxycholic acid, 3-methyladenine, and wortmannin for 12 h. The ER stress-associated genes glucose-regulated protein 78 and C/EBP homologous protein were examined via quantitative real time polymerase chain reaction. Immunostaining with microtubule-associated protein 1 light chain 3 as well as electron microscopy were used to evaluate autophagy activity. Trypan blue exclusion was used to determine hepatocyte cell viability. RESULTS: In both lean and steatotic hepatocytes, we found that TM induced both C/EBP homologous protein and glucose-regulated protein 78 messenger RNA expression. Cells with increased ER stress were undergoing increased autophagy and had a significant decrease in cell viability. Both tauroursodeoxycholic acid and 3-methyladenine treatments attenuated TM induced ER stress, autophagy, and cell death, whereas wortmannin treatment reduced autophagy and cell death but without changing ER stress. CONCLUSIONS: These data suggest that autophagy is a likely downstream mediator of ER stress-induced cell death in rat hepatocytes. Further exploration of the link between autophagy and ER stress in hepatocyte injury will yield important information that may be leveraged for treatment of liver injuries such as ischemia/reperfusion.
Assuntos
Apoptose/fisiologia , Autofagia/fisiologia , Estresse do Retículo Endoplasmático/fisiologia , Fígado Gorduroso/patologia , Hepatócitos/patologia , Adenina/análogos & derivados , Adenina/farmacologia , Androstadienos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Células Cultivadas , Modelos Animais de Doenças , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Masculino , Ratos , Ratos Zucker , Ácido Tauroquenodesoxicólico/farmacologia , Tunicamicina/farmacologia , WortmaninaRESUMO
BACKGROUND: There are little data to explain why the surgical subspecialty of orthopaedic surgery struggles with improving the racial/ethnic composition of its workforce. The current work sought to determine what orthopaedic residency program directors and coordinators believe are the barriers to improving diversity at their own programs. METHODS: Between November 17, 2018, and April 1, 2019, a 17-question survey was electronically distributed to the program directors and coordinators of 155 allopathic orthopaedic surgery residency programs. Seventy-five of 155 programs (48.4%) responded to the survey. A p-value of < 0.05 was used to determine statistical significance. RESULTS: The most commonly stated barriers to increasing diversity within the orthopaedic surgery programs were the following: "We do not have enough minority faculty, which may deter the applicants" (69.3%), "We consistently rank minority applicants high but can never seem to match them" (56%), and "Not enough minorities are applying to our program" (54.7%). Programs with higher percentages of underrepresented minority (URM) faculty had higher percentages of URM residents (p = 0.001). Programs participating in the Nth Dimensions and/or Perry Initiative programs had a higher percentage of URM faculty as compared to the residency programs that did not participate in these programs (p = 0.004). URM residents represented 17.5% of all residents who resigned and/or were dismissed in the 10 years preceding the survey while also only representing 6% of all orthopaedic residents during the same time period. CONCLUSIONS: From the orthopaedic residency program perspective, the greatest perceived barrier to increasing the racial/ethnic diversity of residents in their program is their lack of URM faculty. Surveyed programs with more URM faculty had more URM residents, and programs participating in Nth Dimensions and/or Perry Initiative programs had a higher percentage of URM faculty.