Disruption of cell membranes by Aβ is believed to be one of the key components of Aβ toxicity. However, the mechanism by which this occurs is not fully understood. Here, we demonstrate that membrane disruption by Aβ occurs by a two-step process, with the initial formation of ion-selective pores followed by nonspecific fragmentation of the lipid membrane during amyloid fiber formation. Immediately after the addition of freshly dissolved Aβ(1-40), defects form on the membrane that share many of the properties of Aβ channels originally reported from single-channel electrical recording, such as cation selectivity and the ability to be blockaded by zinc. By contrast, subsequent amyloid fiber formation on the surface of the membrane fragments the membrane in a way that is not cation selective and cannot be stopped by zinc ions. Moreover, we observed that the presence of ganglioside enhances both the initial pore formation and the fiber-dependent membrane fragmentation process. Whereas pore formation by freshly dissolved Aβ(1-40) is weakly observed in the absence of gangliosides, fiber-dependent membrane fragmentation can only be observed in their presence. These results provide insights into the toxicity of Aβ and may aid in the design of specific compounds to alleviate the neurodegeneration of Alzheimer's disease.

The aggregation of amyloidogenic proteins is infamous for being highly chaotic, with small variations in conditions sometimes leading to large changes in aggregation rates. Using the amyloidogenic protein IAPP (islet amyloid polypeptide protein, also known as amylin) as an example, we show that a part of this phenomenon may be related to the formation of micellelike oligomers at specific critical concentrations and temperatures. We show that pyrene fluorescence can sensitively detect micellelike oligomer formation by IAPP and discriminate between micellelike oligomers from fibers and monomers, making pyrene one of the few chemical probes specific to a prefibrillar oligomer. We further show that oligomers of this type reversibly form at critical concentrations in the low micromolar range and at specific critical temperatures. Micellelike oligomer formation has several consequences for amyloid formation by IAPP. First, the kinetics of fiber formation increase substantially as the critical concentration is approached but are nearly independent of concentration below it, suggesting a direct role for the oligomers in fiber formation. Second, the critical concentration is strongly correlated with the propensity to form amyloid: higher critical concentrations are observed for both IAPP variants with lower amyloidogenicity and for native IAPP at acidic pH in which aggregation is greatly slowed. Furthermore, using the DEST NMR technique, we show that the pathway of amyloid formation switches as the critical point is approached, with self-interactions primarily near the N-terminus below the critical temperature and near the central region above the critical temperature, reconciling two apparently conflicting views of the initiation of IAPP aggregation.

Objectives The objective of the current review was to synthesize the literature on intersectionality relative to disparities across the cancer care continuum. A model to support future intersectional cancer research was proposed. Methods Web‐based discovery services and discipline‐specific databases were queried for both peer‐reviewed and gray literature. Study screening and data extraction were facilitated through the Covidence software platform. Results Among 497 screened studies, 28 met study inclusion criteria. Most articles were peer‐reviewed empirical studies (n = 22) that focused on pre‐diagnosis/screening (n = 19) and included marginalized racial/ethnic (n = 22) identities. Pre‐cancer diagnosis, sexual orientation and race influenced women's screening and vaccine behaviors. Sexual minority women, particularly individuals of color, were less likely to engage in cancer prevention behaviors prior to diagnosis. Race and socioeconomic status (SES) were important factors in patient care/survivorship with worse outcomes among non‐white women of low SES. Emergent themes in qualitative results emphasized the importance of patient intersectional identities, as well as feelings of marginalization, fears of discrimination, and general discomfort with providers as barriers to seeking cancer care. Conclusions Patients with intersectional identities often experience barriers to cancer care that adversely impact screening, diagnosis, treatment, as well as survivorship. The use of an “intersectional lens” as a future clinical and research framework will facilitate a more multidimensional and holistic approach to the care of cancer patients.

Background Cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) is indicated for patients with peritoneal dissemination of appendiceal cancer. The role of neoadjuvant chemotherapy (NAC) before CRS‐HIPEC remains controversial. Methods A retrospective review of adult patients who underwent CRS ± HIPEC for metastatic appendiceal cancer between 2000‐2017 was performed. Patients who received NAC followed by surgery were compared with those who underwent surgery first (SF) with and without 1:1 propensity score matching (PSM). Results Among 803 patients with appendiceal cancer who underwent CRS ± HIPEC, 225 (28%) received NAC, and 578 (72%) underwent SF. After PSM (n = 186), median overall survival (OS) did not differ (NAC: 40 vs SF: 56 months; P = .210) but recurrence‐free survival (RFS) was worse among patients who received NAC (14 vs 22 months; P = .007). NAC was independently associated with worse OS (hazards ratio [HR], 1.81; 95% confidence interval [CI], 1.03‐3.18) and RFS (HR, 1.93; 95% CI, 1.25‐2.99). Conclusion In this multi‐institutional retrospective analysis of patients with peritoneal dissemination from appendiceal cancer, the use of NAC before CRS‐HIPEC was associated with worse OS and RFS even after PSM and multivariable regression. Immediate surgery should be considered for patients with disease amenable to complete cytoreduction.

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