Assessment of various standard fish diets on gut microbiome of platyfish Xiphophorus maculatus.

Diet is an external factor that affects the physiological baseline of research animals. It can shape gut microbiome, which can impact the host. As a result, dietary variation can challenge experimental reproducibility and data integration across studies when not appropriately considered. To control for diet-induced variation, reference diets have been developed for common biomedical models. However, such reference diets have not yet been developed for nontraditional model organisms, such as Xiphophorus species. In this study, we compared two diets designed for zebrafish, a commercial zebrafish diet (Gemma and GEM), and a proposed zebrafish reference diet developed by the Watts laboratory at the University of Alabama at Birmingham (WAT) to the Xiphophorus Genetic Stock Center custom diet (CON) to evaluate the influence of diet on the Xiphophorus gut microbiome. Xiphophorus maculatus were fed the three diets from 2 to 6 months of age. Feces were collected and the gut microbiome was assessed using 16S rRNA sequencing every month. We observed substantial diet-driven variation in the gut microbiome. Our results indicate that diets developed specifically for zebrafish can affect the gut microbiome composition and may not be optimal for Xiphophorus.

Assessment of Various Standard Fish Diets on Growth and Fecundity of Platyfish (Xiphophorus maculatus) and Medaka (Oryzias latipes).

Several small freshwater fish species are utilized as models for human conditions and disease in biomedical research. Research animal diets are generally tailored to optimize growth, fecundity, and produce healthy research animals. However, a lack of reference diets presents a barrier in comparative studies between aquatic animal models and even among laboratories using the same species. Therefore, the objective of this study was to determine feeding regime and dietary effects on growth and fecundity in two commonly used freshwater fish, platyfish and medaka. From 1 through 6 months of age, platyfish and medaka were fed one of three feeding regime/diets: (1) our custom feeding regime consists of commercial flake food, beef liver paste, and live brine shrimp (CON); (2) a commercially available zebrafish diet, Gemma (GEM); and (3) a laboratory defined reference feeding regime (WAT). Weight, size, brood numbers, and survival rates for both species were measured monthly. Numbers of platyfish fry and hatch rate of medaka embryos were also determined. We observed that custom feeding regime (CON) fed platyfish and medaka grew larger, exhibited a higher survival rate, and had higher fecundity than WAT or GEM fed fish. These observations suggest that diets and regimes designed for zebrafish are not optimal to maintain platyfish or medaka. Thus, base diets, with clearly defined components and regimes, need to be developed with compositions that can be adjusted in a species-specific manner.

Risk Calculator to Predict 30-Day Readmission After Coronary Artery Bypass: A Strategic Decision Support Tool.

BACKGROUND: Re-admission is an important source of patient dissatisfaction and increased hospital costs. A simple calculator to determine the probability of re-admission may help guide patient dismissal planning. METHODS: Using the national readmissions database (NRD), we identified admissions for isolated primary coronary artery bypass (CABG) and stratified them according to 30-day readmission. Including pre, intra and postoperative variables, we prepared a logistic regression model to determine the probability for re-admission. The model was tested for reliability with boot-strapping and 10-fold cross-validation. RESULTS: From 135,699 procedures, 19,355 were readmitted at least once within 30days of dismissal. Patients who were readmitted were older (67±10 vs 65 ± 10 years, p<0.01), females (32% vs 24%; p<0.01) and had a higher Elixhauser comorbidity score (1.5±1.4 vs 1.1±1.2; p<0.01). Our final model (c- statistic=0.65) consisted of 16 pre and three postoperative factors. End-stage renal disease (OR 1.79 [1.57-2.04]) and length of stay>9days (OR 1.60 [1.52-1.68]) were most prominent indicators for readmission. Compared to Medicaid beneficiaries, those with private insurance (OR 0.62 [0.57-0.68]) and Medicare (OR 0.85 [0.79-0.92]) coverage were less likely to be readmitted. CONCLUSIONS: Our simple 30-days CABG readmission calculator can be used as a strategic tool to help reduce readmissions after coronary artery bypass surgery.