Panel composition and disparities in the topics of presentation in vascular surgery conferences

BACKGROUND

Previous studies identified gender disparities in surgical conference presenters and moderators. We sought to assess disparities in the representation of women in terms of speakers and moderators, but with particular emphasis on panels and topics of discussion at vascular surgery conferences.

METHODS

Data regarding presenters and moderators from the Southern Association of Vascular Surgery, Western Vascular Society, Vascular and Endovascular Surgical Society, Society for Clinical Vascular Surgery, and Society for Vascular Surgery conferences was obtained from online meeting archives and via email correspondence. Scientific session speakers, moderators, and panelists were identified by sex. Specific vascular topics for each discussion were also identified. Keynote speakers or special guests were excluded.

RESULTS

Compared to men, women were less often presenters (18% versus 82%, p < .002) and moderators (16% versus 84%, p < .001) of conference sessions. Women were most likely to present on dialysis access and least likely to present on venous disease overall. Women were more likely to present on aortic (24% vs 19%; p < .013) and cerebrovascular disease (33% vs 27%; p < .021) at regional compared to national conferences. Of panels assessed, 68% were all-male. Subgroup analysis suggests that some improvements have been made over time.

CONCLUSIONS

Significant disparities persist in the topics presented and in panel composition suggesting potential areas for improvement in equity. Further study should focus on evaluating trends in the training level of the presenter and the topics presented, and assessing parity in structural factors that impact research presentation opportunities.

Do surgical emergencies stay at home? Observations from the first United States Coronavirus epicenter

BACKGROUND

During the coronavirus disease 2019 pandemic, New York instituted a statewide stay-at-home mandate to lower viral transmission. While public health guidelines advised continued provision of timely care for patients, disruption of safety-net health care and public fear have been proposed to be related to indirect deaths because of delays in presentation. We hypothesized that admissions for emergency general surgery (EGS) diagnoses would decrease during the pandemic and that mortality for these patients would increase.

METHODS

A multicenter observational study comparing EGS admissions from January to May 2020 to 2018 and 2019 across 11 NYC hospitals in the largest public health care system in the United States was performed. Emergency general surgery diagnoses were defined using International Classification Diseases, Tenth Revision, codes and grouped into seven common diagnosis categories: appendicitis, cholecystitis, small/large bowel, peptic ulcer disease, groin hernia, ventral hernia, and necrotizing soft tissue infection. Baseline demographics were compared including age, race/ethnicity, and payor status. Outcomes included coronavirus disease (COVID) status and mortality.

RESULTS

A total of 1,376 patients were admitted for EGS diagnoses from January to May 2020, a decrease compared with both 2018 (1,789) and 2019 (1,668) (p < 0.0001). This drop was most notable after the stay-at-home mandate (March 22, 2020; week 12). From March to May 2020, 3.3%, 19.2%, and 6.0% of EGS admissions were incidentally COVID positive, respectively. Mortality increased in March to May 2020 compared with 2019 (2.2% vs. 0.7%); this difference was statistically significant between April 2020 and April 2019 (4.1% vs. 0.9%, p = 0.045).

CONCLUSION

Supporting our hypothesis, the coronavirus disease 2019 pandemic and subsequent stay-at-home mandate resulted in decreased EGS admissions between March and May 2020 compared with prior years. During this time, there was also a statistically significant increase in mortality, which peaked at the height of COVID infection rates in our population.

LEVEL OF EVIDENCE

Epidemiological, level IV.

Contribution of Adipose-Derived Factor D/Adipsin to Complement Alternative Pathway Activation: Lessons from Lipodystrophy

Factor D (FD) is an essential component of the complement alternative pathway (AP). It is an attractive pharmaceutical target because it is an AP-specific protease circulating in blood. Most components of the complement activation pathways are produced by the liver, but FD is highly expressed by adipose tissue. Two critical questions are: 1) to what degree does adipose tissue contribute to circulating FD levels and 2) what quantity of FD is sufficient to maintain a functional AP? To address these issues, we studied a novel mouse strain with complete lipodystrophy (LD), the fld mouse with partial LD, an FD-deficient mouse, and samples from lipodystrophic patients. FD was undetectable in the serum of LD mice, which also showed minimal AP function. Reconstitution with purified FD, serum mixing experiments, and studies of partial LD mice all demonstrated that a low level of serum FD is sufficient for normal AP activity in the mouse system. This conclusion was further supported by experiments in which wild-type adipose precursors were transplanted into LD mice. Our results indicate that almost all FD in mouse serum is derived from adipose tissue. In contrast, FD levels were reduced ∼50% in the sera of patients with congenital generalized LD. Our studies further demonstrate that a relatively small amount of serum FD is sufficient to facilitate significant time-dependent AP activity in humans and in mice. Furthermore, this observation highlights the potential importance of obtaining nearly complete inhibition of FD in treating alternative complement activation in various autoimmune and inflammatory human diseases.

Macrophage migration inhibitory factor downregulation: a novel mechanism of resistance to anti-angiogenic therapy

Anti-angiogenic therapies for cancer such as VEGF neutralizing antibody bevacizumab have limited durability. While mechanisms of resistance remain undefined, it is likely that acquired resistance to anti-angiogenic therapy will involve alterations of the tumor microenvironment. We confirmed increased tumor-associated macrophages in bevacizumab-resistant glioblastoma patient specimens and two novel glioblastoma xenograft models of bevacizumab resistance. Microarray analysis suggested downregulated macrophage migration inhibitory factor (MIF) to be the most pertinent mediator of increased macrophages. Bevacizumab-resistant patient glioblastomas and both novel xenograft models of resistance had less MIF than bevacizumab-naive tumors, and harbored more M2/protumoral macrophages that specifically localized to the tumor edge. Xenografts expressing MIF-shRNA grew more rapidly with greater angiogenesis and had macrophages localizing to the tumor edge which were more prevalent and proliferative, and displayed M2 polarization, whereas bevacizumab-resistant xenografts transduced to upregulate MIF exhibited the opposite changes. Bone marrow-derived macrophage were polarized to an M2 phenotype in the presence of condition-media derived from bevacizumab-resistant xenograft-derived cells, while recombinant MIF drove M1 polarization. Media from macrophages exposed to bevacizumab-resistant tumor cell conditioned media increased glioma cell proliferation compared with media from macrophages exposed to bevacizumab-responsive tumor cell media, suggesting that macrophage polarization in bevacizumab-resistant xenografts is the source of their aggressive biology and results from a secreted factor. Two mechanisms of bevacizumab-induced MIF reduction were identified: (1) bevacizumab bound MIF and blocked MIF-induced M1 polarization of macrophages; and (2) VEGF increased glioma MIF production in a VEGFR2-dependent manner, suggesting that bevacizumab-induced VEGF depletion would downregulate MIF. Site-directed biopsies revealed enriched MIF and VEGF at the enhancing edge in bevacizumab-naive patients. This MIF enrichment was lost in bevacizumab-resistant glioblastomas, driving a tumor edge M1-to-M2 transition. Thus, bevacizumab resistance is driven by reduced MIF at the tumor edge causing proliferative expansion of M2 macrophages, which in turn promotes tumor growth.

GLUT3 upregulation promotes metabolic reprogramming associated with antiangiogenic therapy resistance

Clinical trials revealed limited response duration of glioblastomas to VEGF-neutralizing antibody bevacizumab. Thriving in the devascularized microenvironment occurring after antiangiogenic therapy requires tumor cell adaptation to decreased glucose, with 50% less glucose identified in bevacizumab-treated xenografts. Compared with bevacizumab-responsive xenograft cells, resistant cells exhibited increased glucose uptake, glycolysis, ¹³C NMR pyruvate to lactate conversion, and survival in low glucose. Glucose transporter 3 (GLUT3) was upregulated in bevacizumab-resistant versus sensitive xenografts and patient specimens in a HIF-1α-dependent manner. Resistant versus sensitive cell mitochondria in oxidative phosphorylation-selective conditions produced less ATP. Despite unchanged mitochondrial numbers, normoxic resistant cells had lower mitochondrial membrane potential than sensitive cells, confirming poorer mitochondrial health, but avoided the mitochondrial dysfunction of hypoxic sensitive cells. Thin-layer chromatography revealed increased triglycerides in bevacizumab-resistant versus sensitive xenografts, a change driven by mitochondrial stress. A glycogen synthase kinase-3β inhibitor suppressing GLUT3 transcription caused greater cell death in bevacizumab-resistant than -responsive cells. Overexpressing GLUT3 in tumor cells recapitulated bevacizumab-resistant cell features: survival and proliferation in low glucose, increased glycolysis, impaired oxidative phosphorylation, and rapid in vivo proliferation only slowed by bevacizumab to that of untreated bevacizumab-responsive tumors. Targeting GLUT3 or the increased glycolysis reliance in resistant tumors could unlock the potential of antiangiogenic treatments.

Dexamethasone-mediated changes in adipose triacylglycerol metabolism are exaggerated, not diminished, in the absence of a functional GR dimerization domain

The glucocorticoid (GC) receptor (GR) has multiple effector mechanisms, including dimerization-mediated transactivation of target genes via DNA binding and transcriptional repression mediated by protein-protein interactions. Much attention has been focused on developing selective GR modulators that would dissociate adverse effects from therapeutic anti-inflammatory effects. The GR(dim/dim) mouse has a mutation in the dimerization domain of GR and has been shown to have attenuated transactivation with intact repression. To understand the role of GR dimerization-dependent targets in multiple tissues, we measured metabolic fluxes through several disease-relevant GC target pathways using heavy water labeling and mass spectrometry in wild-type and GR(dim/dim) mice administered the potent GC dexamethasone (DEX). Absolute triglyceride synthesis was increased in both wild-type and GR(dim/dim) mice by DEX in the inguinal and epididymal fat depots. GR(dim/dim) mice showed an exaggerated response to DEX in both depots. De novo lipogenesis was also greatly increased in both depots in response to DEX in GR(dim/dim), but not wild-type mice. In contrast, the inhibitory effect of DEX on bone and skin collagen synthesis rates was greater in wild-type compared with GR(dim/dim) mice. Wild-type mice were more sensitive to DEX-dependent decreases in insulin sensitivity than GR(dim/dim) mice. Wild-type and GR(dim/dim) mice were equally sensitive to DEX-dependent decreases in muscle protein synthesis. Chronic elevation of GCs in GR(dim/dim) mice results in severe runting and lethality. In conclusion, some metabolic effects of GC treatment are exaggerated in adipose tissue of GR(dim/dim) mice, suggesting that selective GR modulators based on dissociating GR transactivation from repression should be evaluated carefully.