713 research outputs found
Optimal gradual annuitization : quantifying the costs of switching to annuities
We compute the optimal dynamic asset allocation policy for a retiree with Epstein-Zin utility. The retiree can decide how much he consumes and how much he invests in stocks, bonds, and annuities. Pricing the annuities we account for asymmetric mortality beliefs and administration expenses. We show that the retiree does not purchase annuities only once but rather several times during retirement (gradual annuitization). We analyze the case in which the retiree is restricted to buy annuities only once and has to perform a (complete or partial) switching strategy. This restriction reduces both the utility and the demand for annuities
Money in Motion: Dynamic Portfolio Choice in Retirement
Retirees confront the difficult problem of how to manage their money in retirement so as to not outlive their funds while continuing to invest in capital markets. We posit a dynamic utility maximizer who makes both asset location and allocation decisions when managing her retirement financial wealth and annuities, and we prove that she can benefit from both the equity premium and longevity insurance in her retirement portfolio. Even without bequests, she will not fully annuitize; rather, her optimal stock allocation amounts initially to more than half of her financial wealth and declines with age. Welfare gains from this strategy can amount to 40 percent of financial wealth (depending on risk parameters and other resources). In practice, it turns out that many retirees will do almost as well by purchasing a variable annuity invested 60/40 in stocks/bonds.
Asset Allocation and Location over the Life Cycle with Survival-Contingent Payouts
This paper shows how lifelong survival-contingent payouts can enhance investor wellbeing in the context of a portfolio choice model which integrates uninsurable labor income and asymmetric mortality expectations. Our model generates optimal asset location patterns indicating how much to hold in liquid versus illiquid survival-contingent payouts over the lifetime, and also asset allocation paths, showing how to invest in stocks versus bonds. We conrm that the investor will gradually move money out of her liquid saving into survivalcontingent assets to retirement and beyond, thereby enhancing her welfare by as much as 50 percent. The results are also robust to the introduction of uninsurable consumption shocks in housing expenses, income flows during the worklife and retirement, sudden changes in health status, and medical expenses.
Dimethyl Fumarate Alleviates Dextran Sulfate Sodium-Induced Colitis, through the Activation of Nrf2-Mediated Antioxidant and Anti-inflammatory Pathways.
Oxidative stress and chronic inflammation play critical roles in the pathogenesis of ulcerative colitis (UC) and inflammatory bowel diseases (IBD). A previous study has demonstrated that dimethyl fumarate (DMF) protects mice from dextran sulfate sodium (DSS)-induced colitis via its potential antioxidant capacity, and by inhibiting the activation of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome. This study aims to clarify the nuclear factor erythroid 2-related factor 2/antioxidant responsive element (Nrf2/ARE) pathway pharmacological activation and anti-inflammatory effect by DMF, through focusing on other crucial antioxidant enzymes and inflammatory mediator, including glutamate-cysteine ligase catalytic subunit (GCLC), glutathione peroxidase (GPX) and cyclooxygenase-2 (COX-2), in a DSS-induced colitis mouse model. The oral administration of DMF attenuated the shortening of colons and alleviated colonic inflammation. Furthermore, the expression of key antioxidant enzymes, including GCLC and GPX, in the colonic tissue were significantly increased by DMF administration. In addition, protein expression of the inflammatory mediator, COX-2, was reduced by DMF administration. Our results suggest that DMF alleviates DSS-induced colonic inflammatory damage, likely via up-regulating GCLC and GPX and down-regulating COX-2 protein expression in colonic tissue
Asset Allocation and Location over the Life Cycle with Survival-Contingent Payouts
This paper shows how lifelong survival-contingent payouts can enhance investor wellbeing in the context of a portfolio choice model which integrates uninsurable labor income and asymmetric mortality expectations. Our model generates optimal asset location patterns indicating how much to hold in liquid versus illiquid survival-contingent payouts over the lifetime, and also asset allocation paths, showing how to invest in stocks versus bonds. We confirm that the investor will gradually move money out of her liquid saving into survival-contingent assets to retirement and beyond, thereby enhancing her welfare by as much as 50 percent. The results are also robust to the introduction of uninsurable consumption shocks in housing expenses, income flows during the worklife and retirement, sudden changes in health status, and medical expenses.
Results of a phase I pilot clinical trial examining the effect of plant-derived resveratrol and grape powder on Wnt pathway target gene expression in colonic mucosa and colon cancer
Anthony V Nguyen1, Micaela Martinez1, Michael J Stamos2, Mary P Moyer3, Kestutis Planutis1, Christopher Hope1 Randall F Holcombe11Division of Hematology/Oncology and Chao Family Comprehensive Cancer Center, 2Department of Surgery, University of California, Irvine CA, USA; 3Incell Corporation, San Antonio, TX USAContext: Resveratrol exhibits colon cancer prevention activity in animal models; it is purported to have this activity in humans and inhibit a key signaling pathway involved in colon cancer initiation, the Wnt pathway, in vitro.Design: A phase I pilot study in patients with colon cancer was performed to evaluate the effects of a low dose of plant-derived resveratrol formulation and resveratrol-containing freeze-dried grape powder (GP) on Wnt signaling in the colon. Eight patients were enrolled and normal colonic mucosa and colon cancer tissue were evaluated by Wnt pathway-specific microarray and quantitative real-time polymerase chain reaction (qRT-PCR) pre- and post-exposure to resveratrol/GP.Results: Based on the expression of a panel of Wnt target genes, resveratrol/GP did not inhibit the Wnt pathway in colon cancer but had significant (p < 0.03) activity in inhibiting Wnt target gene expression in normal colonic mucosa. The greatest effect on Wnt target gene expression was seen following ingestion of 80 g of GP per day (p < 0.001). These results were confirmed with qRT-PCR of cyclinD1 and axinII. The inhibitory effect of GP on Wnt signal throughput was confirmed in vitro with a normal colonic mucosa-derived cell line.Conclusions: These data suggest that GP, which contains low dosages of resveratrol in combination with other bioactive components, can inhibit the Wnt pathway in vivo and that this effect is confined to the normal colonic mucosa. Further study of dietary supplementation with resveratrol-containing foods such as whole grapes or GP as a potential colon cancer preventive strategy is warranted.Trial registration: NCT00256334.Keywords: resveratrol, clinical trial, colon cancer, Wnt signaling, grapes, cancer preventio
Life-Cycle Asset Allocation with Annuity Markets: Is Longevity Insurance a Good Deal?
We derive the optimal portfolio choice over the life-cycle for households facing labor income, capital market, and mortality risk. In addition to stocks and bonds, households also have access to incomplete annuity markets offering a hedge against mortality risk. We show that a considerable fraction of wealth should be annuitized to skim the return enhancing mortality credit. The remaining liquid wealth (stocks and bonds) is used to hedge labor income risk during work life, to earn the equity premium, and to ensure estate for the heirs. Furthermore, we assess the importance of common explanations for limited participation in annuity markets.http://deepblue.lib.umich.edu/bitstream/2027.42/49332/2/wp146.pd
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Intraoperative Anastomotic Evaluation Methods: Rigid Proctoscopy Versus Flexible Endoscopy
IntroductionRigid proctosigmoidoscopy (RP) and flexible sigmoidoscopy (FS) are two modalities commonly used for intraoperative evaluation of colorectal anastomoses. This study seeks to determine whether there is an association between the endoscopic modality used to evaluate colorectal anastomoses and the rate of anastomotic leak (AL), organ space infection, and overall infectious complication.MethodsThe 2012-2018 American College of Surgeons National Surgical Quality Improvement Program database was queried for patients undergoing colorectal anastomoses. Anastomotic evaluation method (RP versus FS) was identified by Current Procedural Terminologycoding and used for group classification. Outcomes measured included AL, organ space infections, and overall infection. Multivariable logistic regression analysis for predicting AL was performed.ResultsWe identified 7100 patients who underwent a colorectal anastomosis with intraoperative endoscopic evaluation. RP was utilized in 3397 (47.8%) and FS in 3703 (52.2%) patients. RP was used more commonly in diverticulitis (44.5% versus 36.2%, P < 0.01), while FS was used more frequently in malignancy (47.5% versus 36.7%, P < 0.01). Anastomotic evaluation with FS was associated with lower rates of organ space infection (3.8% versus 4.8%, P = 0.025) and AL (2.9% versus 3.8%, P = 0.028) compared to RP. On multivariate logistic regression modeling, anastomotic evaluation with RP was associated with a higher risk of AL (odds ratio 1.403, 95% CI 1.028-1.916, P = 0.033) compared to FS.ConclusionsCompared to FS, rigid proctosigmoidoscopic evaluation of a colorectal anastomosis was associated with an increased rate of AL and organ space infection
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Surgical Outcome in Laparoscopic Abdominal Surgical Operations with Clostridium Difficile Infection
Introduction: Postoperative Clostridium difficile infection (CDI) has associated morbidity, but it is unknown how it impacts different operations. We sought to determine the incidence and postoperative morbidity following abdominal surgery.Method: The National Surgical Quality Improvement Program database (2015-2019) was utilized to evaluate adult (≥18 years-old) patients who developed CDI following laparoscopic abdominal operations. Univariate and multivariate analysis were performed to evaluate outcomes.Results: A total of 973 338 patients were studied and the overall incidence of CDI was .3% within 30 days of operation. Colorectal surgery had the highest incidence of CDI (1601/167 949,1.0%) with significantly longer mean length of stay (LOS) (8.0 days± 9.0, P < .01) compared to other surgical procedures. CDI patients also had a longer mean length of stay (6.6± 8.0 vs 2.1 ± 3.6 days, P < .01) and increased mortality (1.8% vs .2%, AOR: 4.64, CI: 3.45-5.67, P < .01) compared to patients without CDI.Conclusions: This national analysis demonstrates that CDI is a significant complication following abdominal surgery and is associated with increased LOS and mortality. Furthermore, laparoscopic colorectal surgery appears to have the greatest risk of CDI. Future research is needed to determine the exact cause in order to decrease the incidence of CDI by reconsidering the protocol of antibiotic use within the high-risk population
Perfusion Assessment in Laparoscopic Left-Sided/Anterior Resection (PILLAR II): A Multi-Institutional Study
BackgroundOur primary objective was to demonstrate the utility and feasibility of the intraoperative assessment of colon and rectal perfusion using fluorescence angiography (FA) during left-sided colectomy and anterior resection. Anastomotic leak (AL) after colorectal resection increases morbidity, mortality, and, in cancer cases, recurrence rates. Inadequate perfusion may contribute to AL. The PINPOINT Endoscopic Fluorescence Imaging System allows for intraoperative assessment of anastomotic perfusion.Study DesignThis is a prospective, multicenter, open-label, clinical trial that assessed the feasibility and utility of FA for intraoperative perfusion assessment during left-sided colectomy and anterior resection at 11 centers in the United States.ResultsA total of 147 patients were enrolled, of whom 139 were eligible for analysis. Diverticulitis (44%), rectal cancer (25%), and colon cancer (21%) were the most prevalent indications for surgery. The mean level of anastomosis was 10 ± 4 cm from the anal verge. Splenic-flexure mobilization was performed in 81% and high ligation of the inferior mesenteric artery in 61.9% of patients. There was a 99% success rate for FA, and FA changed surgical plans in 11 (8%) patients, with the majority of changes occurring at the time of transection of the proximal margin (7%). Overall morbidity rates were 17%. The anastomotic leak rate was 1.4% (n = 2). There were no anastomotic leaks in the 11 patients who had a change in surgical plan based on intraoperative perfusion assessment with FA.ConclusionsPINPOINT is a safe and feasible tool for intraoperative assessment of tissue perfusion during colorectal resection. There were no anastomotic leaks in patients in whom the anastomosis was revised based on inadequate perfusion with FA
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