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Describes what avalanches are, how they occur, and how to protect oneself from avalanches.

Presented are the results of the application of the Multigrid method for the discrete solution of two fundamental computational problems in chemistry: the solution for the ground state wavefunctions of a system of electrons and nuclei and the calculation of the electrostatic potential for systems of charged particles. The solution of the electrostatic potential will be discussed as an isolated calculation and as part of the quantum mechanical eigenvalue problem. Comparisons to existing methods will be given when possible in addition to the idiosyncrasies of the Multigrid method and discrete methods in general. Computational advantages of the Multigrid method as well as some programming details will be discussed in order to give insight into the possible advantages and limitations of discrete methods.

An in vitro model of human ovarian follicles would greatly benefit the study of female reproduction. Ovarian development requires the combination of germ cells and several types of somatic cells. Among these, granulosa cells play a key role in follicle formation and support for oogenesis. Whereas efficient protocols exist for generating human primordial germ cell-like cells (hPGCLCs) from human induced pluripotent stem cells (hiPSCs), a method of generating granulosa cells has been elusive. Here, we report that simultaneous overexpression of two transcription factors (TFs) can direct the differentiation of hiPSCs to granulosa-like cells. We elucidate the regulatory effects of several granulosa-related TFs and establish that overexpression of NR5A1 and either RUNX1 or RUNX2 is sufficient to generate granulosa-like cells. Our granulosa-like cells have transcriptomes similar to human fetal ovarian cells and recapitulate key ovarian phenotypes including follicle formation and steroidogenesis. When aggregated with hPGCLCs, our cells form ovary-like organoids (ovaroids) and support hPGCLC development from the premigratory to the gonadal stage as measured by induction of DAZL expression. This model system will provide unique opportunities for studying human ovarian biology and may enable the development of therapies for female reproductive health. Ovaries are responsible for forming the eggs humans and other mammals need to reproduce. Once mature, the egg cell is released into the fallopian tube where it can be potentially fertilized by a sperm. Despite their crucial role, how eggs are made in the ovary is poorly understood. This is because ovaries are hard to access, making it difficult to conduct experiments on them. To overcome this, researchers have built artificial ovaries in the laboratory using stem cells from the embryos of mice which can develop into all cell types in the adult body. By culturing these embryonic stem cells under special conditions, researchers can convert them in to the two main cell types of the developing ovary: germ cells which go on to form eggs, and granulosa cells which help eggs grow and mature. The resulting lab-grown ovary can make eggs that produce live mice when fertilized. This approach has also been applied to human induced pluripotent stem cells (iPSCs), adult human cells which have been reprogrammed to a stem-like state. While this has produced human germ cells, generating human granulosa cells has been more challenging. Here, Pierson Smela, Kramme et al. show that activating a specific set of transcription factors (proteins that switch genes on or off) in iPSCs can make them transition to granulosa cells. First, the team tested random combinations of 35 transcription factors which, based on previous literature and genetic data, were likely to play a role in the formation of granulosa cells. This led to the identification of a small number of factors that caused the human iPSCs to develop features and carry out roles seen in mature granulosa cells; this includes producing an important reproductive hormone and supporting the maturation of germ cells. Pierson Smela, Kramme et al. found that growing these granulosa-like cells together with germ cells (also generated via iPSCs) resulted in structures similar to ovarian follicles which help eggs develop. These findings could help researchers build stable systems for studying how granulosa cells behave in human ovaries. This could lead to new insights about reproductive health.

Fatty tissue can expand in two ways: through increases in the size of individual adipocytes or through increases in the number of adipocytes. The former process promotes metabolic disease, and the latter protects against it. Merrick et al. used single-cell RNA sequencing to define the hierarchy of mesenchymal progenitor cells that give rise to adipose tissue in mice and humans (see the Perspective by Chau and Cawthorn). They found that progenitor cells expressing a protein called DPP4 give rise to two distinct types of preadipocytes in response to different signals. The DPP4 progenitors reside in a fluid-filled network of collagen and elastin fibers surrounding adipose tissue. In principle, therapeutic interventions that increase progenitor cell differentiation into adipocytes could ameliorate metabolic disease. Science , this issue p. eaav2501 ; see also p. 328 Fat cells arise from multipotent progenitor cells in the reticular interstitium, a recently recognized anatomical niche. Metabolic health depends on the capacity of adipose tissue progenitor cells to undergo de novo adipogenesis. The cellular hierarchy and mechanisms governing adipocyte progenitor differentiation are incompletely understood. Through single-cell RNA sequence analyses, we show that the lineage hierarchy of adipocyte progenitors consists of distinct mesenchymal cell types that are present in both mouse and human adipose tissues. Cells marked by dipeptidyl peptidase–4 (DPP4)/CD26 expression are highly proliferative, multipotent progenitors. During the development of subcutaneous adipose tissue in mice, these progenitor cells give rise to intercellular adhesion molecule–1 (ICAM1)/CD54–expressing (CD54+) committed preadipocytes and a related adipogenic cell population marked by Clec11a and F3 /CD142 expression. Transforming growth factor–β maintains DPP4+ cell identity and inhibits adipogenic commitment of DPP4+ and CD142+ cells. Notably, DPP4+ progenitors reside in the reticular interstitium, a recently appreciated fluid-filled space within and between tissues, including adipose depots.

Preclinical studies suggest that treatment with neoadjuvant immune checkpoint blockade is associated with enhanced survival and antigen-specific T cell responses compared with adjuvant treatment 1 ; however, optimal regimens have not been defined. Here we report results from a randomized phase 2 study of neoadjuvant nivolumab versus combined ipilimumab with nivolumab in 23 patients with high-risk resectable melanoma ( NCT02519322 ). RECIST overall response rates (ORR), pathologic complete response rates (pCR), treatment-related adverse events (trAEs) and immune correlates of response were assessed. Treatment with combined ipilimumab and nivolumab yielded high response rates (RECIST ORR 73%, pCR 45%) but substantial toxicity (73% grade 3 trAEs), whereas treatment with nivolumab monotherapy yielded modest responses (ORR 25%, pCR 25%) and low toxicity (8% grade 3 trAEs). Immune correlates of response were identified, demonstrating higher lymphoid infiltrates in responders to both therapies and a more clonal and diverse T cell infiltrate in responders to nivolumab monotherapy. These results describe the feasibility of neoadjuvant immune checkpoint blockade in melanoma and emphasize the need for additional studies to optimize treatment regimens and to validate putative biomarkers. Neoadjuvant combination treatment with nivolumab and ipilimumab in patients with high-risk melanoma results in higher response rates than nivolumab monotherapy and warrants future optimization of dosing regimens to preserve efficacy while limiting toxicity.

Treatment with therapy targeting BRAF and MEK (BRAF/MEK) has revolutionized care in melanoma and other cancers; however, therapeutic resistance is common and innovative treatment strategies are needed 1 , 2 . Here we studied a group of patients with melanoma who were treated with neoadjuvant BRAF/MEK-targeted therapy ( NCT02231775 , n  = 51) and observed significantly higher rates of major pathological response (MPR; ≤10% viable tumour at resection) and improved recurrence-free survival (RFS) in female versus male patients (MPR, 66% versus 14%, P  = 0.001; RFS, 64% versus 32% at 2 years, P  = 0.021). The findings were validated in several additional cohorts 2 – 4 of patients with unresectable metastatic melanoma who were treated with BRAF- and/or MEK-targeted therapy ( n  = 664 patients in total), demonstrating improved progression-free survival and overall survival in female versus male patients in several of these studies. Studies in preclinical models demonstrated significantly impaired anti-tumour activity in male versus female mice after BRAF/MEK-targeted therapy ( P  = 0.006), with significantly higher expression of the androgen receptor in tumours of male and female BRAF/MEK-treated mice versus the control ( P  = 0.0006 and P  = 0.0025). Pharmacological inhibition of androgen receptor signalling improved responses to BRAF/MEK-targeted therapy in male and female mice ( P  = 0.018 and P  = 0.003), whereas induction of androgen receptor signalling (through testosterone administration) was associated with a significantly impaired response to BRAF/MEK-targeted therapy in male and female patients ( P  = 0.021 and P  < 0.0001). Together, these results have important implications for therapy. Treatment with neoadjuvant BRAF/MEK-targeted therapy results in higher rates of major pathological response in female compared with male patients with melanoma, and pharmacological inhibition of androgen receptor signalling improved the responses of male and female mice to BRAF/MEK-targeted therapy.

Dual BRAF and MEK inhibition produces a response in a large number of patients with stage IV BRAF-mutant melanoma. The existing standard of care for patients with clinical stage III melanoma is upfront surgery and consideration for adjuvant therapy, which is insufficient to cure most patients. Neoadjuvant targeted therapy with BRAF and MEK inhibitors (such as dabrafenib and trametinib) might provide clinical benefit in this high-risk p opulation. We undertook this single-centre, open-label, randomised phase 2 trial at the University of Texas MD Anderson Cancer Center (Houston, TX, USA). Eligible participants were adult patients (aged ≥18 years) with histologically or cytologically confirmed surgically resectable clinical stage III or oligometastatic stage IV BRAFV600E or BRAFV600K (ie, Val600Glu or Val600Lys)-mutated melanoma. Eligible patients had to have an Eastern Cooperative Oncology Group performance status of 0 or 1, a life expectancy of more than 3 years, and no previous exposure to BRAF or MEK inhibitors. Exclusion criteria included metastases to bone, brain, or other sites where complete surgical excision was in doubt. We randomly assigned patients (1:2) to either upfront surgery and consideration for adjuvant therapy (standard of care group) or neoadjuvant plus adjuvant dabrafenib and trametinib (8 weeks of neoadjuvant oral dabrafenib 150 mg twice per day and oral trametinib 2 mg per day followed by surgery, then up to 44 weeks of adjuvant dabrafenib plus trametinib starting 1 week after surgery for a total of 52 weeks of treatment). Randomisation was not masked and was implemented by the clinical trial conduct website maintained by the trial centre. Patients were stratified by disease stage. The primary endpoint was investigator-assessed event-free survival (ie, patients who were alive without disease progression) at 12 months in the intent-to-treat population. This trial is registered at ClinicalTrials.gov, number NCT02231775. Between Oct 23, 2014, and April 13, 2016, we randomly assigned seven patients to standard of care, and 14 to neoadjuvant plus adjuvant dabrafenib and trametinib. The trial was stopped early after a prespecified interim safety analysis that occurred after a quarter of the participants had been accrued revealed significantly longer event-free survival with neoadjuvant plus adjuvant dabrafenib and trametinib than with standard of care. After a median follow-up of 18·6 months (IQR 14·6–23·1), significantly more patients receiving neoadjuvant plus adjuvant dabrafenib and trametinib were alive without disease progression than those receiving standard of care (ten [71%] of 14 patients vs none of seven in the standard of care group; median event-free survival was 19·7 months [16·2–not estimable] vs 2·9 months [95% CI 1·7–not estimable]; hazard ratio 0·016, 95% CI 0·00012–0·14, p<0·0001). Neoadjuvant plus adjuvant dabrafenib and trametinib were well tolerated with no occurrence of grade 4 adverse events or treatment-related deaths. The most common adverse events in the neoadjuvant plus adjuvant dabrafenib and trametinib group were expected grade 1–2 toxicities including chills (12 patients [92%]), headache (12 [92%]), and pyrexia (ten [77%]). The most common grade 3 adverse event was diarrhoea (two patients [15%]). Neoadjuvant plus adjuvant dabrafenib and trametinib significantly improved event-free survival versus standard of care in patients with high-risk, surgically resectable, clinical stage III–IV melanoma. Although the trial finished early, limiting generalisability of the results, the findings provide proof-of-concept and support the rationale for further investigation of neoadjuvant approaches in this disease. This trial is currently continuing accrual as a single-arm study of neoadjuvant plus adjuvant dabrafenib and trametinib. Novartis Pharmaceuticals Corporation.

Background As the Coronavirus Disease-2019 (COVID-19) pandemic continues, healthcare providers struggle to manage both COVID-19 and non-COVID patients while still providing high-quality care. We conducted a systematic review/meta-analysis to describe the effects of the COVID-19 pandemic on patients with non-COVID illness and on healthcare systems compared to non-pandemic epochs. Methods We searched Ovid MEDLINE/EMBASE/Cochrane Database of Systematic Reviews/CENTRAL/CINAHL (inception to December 31, 2020). All study types with COVID-pandemic time period (after December 31, 2019) with comparative non-pandemic time periods (prior to December 31, 2019). Data regarding study characteristics/case-mix/interventions/comparators/ outcomes (primary: mortality; secondary: morbidity/hospitalizations/disruptions-to-care. Paired reviewers conducted screening and abstraction, with conflicts resolved by discussion. Effect sizes for specific therapies were pooled using random-effects models. Risk of bias was assessed by Newcastle-Ottawa Scale, with evidence rating using GRADE methodology. Results Of 11,581 citations, 167 studies met eligibility. Our meta-analysis showed an increased mortality of 16% during the COVID pandemic for non-COVID illness compared with 11% mortality during the pre-pandemic period (RR 1.38, 95% CI: 1.28–1.50; absolute risk difference: 5% [95% CI: 4–6%], p<0.00001, very low certainty evidence). Twenty-eight studies (17%) reported significant changes in morbidity (where 93% reported increases), while 30 studies (18%) reported no significant change (very low certainty). Thirty-nine studies (23%) reported significant changes in hospitalizations (97% reporting decreases), while 111 studies (66%) reported no significant change (very low certainty). Sixty-two studies (37%) reported significant disruptions in standards-to-care (73% reporting increases), while 62 studies (37%) reported no significant change (very low certainty). Conclusions There was a significant increase in mortality during the COVID pandemic compared to pre-pandemic times for non-COVID illnesses. When significant changes were reported, there was increased morbidity, decreased hospitalizations and increased disruptions in standards-of-care. Systematic review registration PROSPERO CRD42020201256 (Sept 2, 2020).

Context .- In an era in which testing of patient tumor material for molecular and other ancillary studies is of increasing clinical importance for selection of therapy, the ability to test on small samplings becomes critical. Often, small samplings are rapidly depleted in the diagnostic workup or are insufficient for multiple ancillary testing approaches. Objective .- To describe technical methodologies that can be implemented to preserve and maximize tissue for molecular and other ancillary testing. Data Sources .- Retrospective analysis of a case cohort from the University of Colorado, description of techniques used at the University of Colorado, and published literature. Conclusions .- Numerous techniques can be deployed to maximize molecular and other ancillary testing, even when specimens are from small samplings. A dedicated process for molecular prioritization has a high success rate, but also increases workload, which must be factored into establishing such a process. Additionally, establishing high-fidelity communication strings is critical for success of dedicated molecular prioritization of samples. Numerous approaches can be deployed for alternative specimen types, and several technical approaches can also aid in maximizing small specimens.