Design and Development of a Computational Tool for a Dialyzer by Using Computational Fluid Dynamic (CFD) Model

In order to reduce the hemodialysis cost and duration, an investigation of the effect of dialyzer design and process variables on the solute clearance rate is required. It is not easy to translate the in vivo transfer process with in vitro experiments, as it involves a high cost to produce various designs and membranes for the dialyzer. The primary objective of this study was the design and development of a computational tool for a dialyzer by using a computational fluid dynamic (CFD) model. Due to their complexity, only researchers with expertise in computational analysis can use dialyzer models. Therefore, COMSOL Inc. (Stockholm, Sweden) has made an application on membrane dialysis to study the impact of different design and process parameters on dialyzed liquid concentration. Still, membrane mathematical modeling is not considered in this application. This void hinders an investigation of the impact of membrane characteristics on the solute clearance rate. This study has developed a stand-alone computational tool in COMSOL Multiphysics 5.4 to fill this void. A review of the literature conducted shows that there are no suitable stand-alone computational tools for kidney dialysis. Very little work has been undertaken to validate the stand-alone computational tool. Medical staff in the hospitals require a computational tool that can be installed quickly and provide results with limited knowledge of dialysis. This work aims to construct a user-friendly computational tool to solve this problem. The development of a user-friendly stand-alone computational tool for the dialyzer is described thoroughly. This application simulates a mathematical model with the Finite Element Method using the COMSOL Multiphysics solver. The software tool is converted to a stand-alone version with the COMSOL compiler. The stand-alone computational tool provides the clearance rate of six different toxins and module packing density. Compared with the previous application, the stand-alone computational tool of membrane dialysis enables the user to investigate the impact of membrane characteristics and process parameters on the clearance rate of different solutes. The results are also inconsistent with the literature data, and the differences ranges are 0.09–6.35% and 0.22–2.63% for urea clearance rate and glucose clearance rate, respectively. Statistical analysis of the results is presented as mean with 95% confidence intervals (CIs) and p values 0.9472 and 0.833 of the urea and glucose clearance rates, respectively.

PSVII-18 Association of post-absorptive glucose and acetate metabolism with feed intake, growth, and efficiency in finishing beef heifers

Glucose and acetate are important nutrients for muscle and fat accretion in beef cattle. The objective of this experiment was to determine if the demand for acetate and glucose, as well as insulin response to glucose, are associated with dry matter intake (DMI), average daily gain (ADG), residual feed intake (RFI), and gain:feed (G:F). Charolais heifers (n = 16; initial BW = 412 ± 10 kg) were trained to close human contact and fed a finishing diet ad libitum in an Insentec feeding system. Following a 12-hour fast, a jugular catheter was inserted, and an acetate clearance test was performed by infusing acetate (2.18 mmol/kg BW0.75) and collecting blood samples over a 30-minute period. One hour after the conclusion of the acetate test, a glucose clearance test was performed by infusing glucose (7.57 mmol/kg BW0.75) and collecting samples over a two-hour period. Four days after the metabolic tests, heifers began an 84-d DMI and ADG test period. The area under the acetate, glucose, and insulin curves were calculated as were the clearance rate, peaks, nadir, and insulin time to peak. Pearson correlations were calculated for the metabolic parameters and production traits using SAS 9.4. Heifers gained 1.69 ± 0.03 kg/d and consumed 10.4 ± 0.19 kg/d. Acetate and glucose clearance rates were not associated with any production trait (P > 0.40). Insulin time to peak concentration after the glucose challenge was associated (r = 0.69; P = 0.003) with G:F, but peak concentration was not (P = 0.45). Additionally, there was a trend (r = 0.40; P = 0.13) for area under the insulin curve to be associated with G:F. Given the small sample size in this experiment, it is possible that decreased insulin sensitivity early in the finishing period is related to improved feed efficiency in finishing heifers.

PSI-12 Effects of increasing rumen propionate on dry matter intake, feeding behavior, glucose clearance, and insulin response in cattle on a finishing ration

The objective of this experiment was to determine if increasing propionate alters dry matter intake (DMI), feeding behavior, glucose clearance rate, blood metabolites, insulin concentrations, and rumen fluid lactate in steers fed a finishing diet. Ruminally cannulated Holstein steers (n = 6) were fed a finishing diet ad libitum. Steers were randomly assigned to one of three treatments in a 3×6 Latin rectangle design. Treatments of no Ca propionate (CON), 100 g/d (LOW), or 300 g/d (HIGH) were ruminally dosed daily. Individual DMI was measured using an Insentec feeding system. Weekly blood samples and body weight were collected on d 0, 7, and 14 and analyzed for glucose, lactate, NEFA, and insulin. A glucose tolerance test was conducted on d 14 of each period. Data were analyzed using a mixed model with period, treatment, time, and their interaction included, with time within period as a repeated measure, and steer as a random effect. Dry matter intake, meal size, and number of meals per day were decreased (P < 0.049) in HIGH steers. Weekly plasma glucose tended (P = 0.07) to be greater on d 7 than d 0. Plasma insulin was lower (P = 0.019) in both LOW and HIGH than CON steers. Rumen fluid lactate was decreased (P = 0.034) in HIGH steers. There was an effect of time (P < 0.0001) on rumen fluid lactate and pH, with an increase from 0 h to 6 h. There was no treatment effect (P ≥ 0.11) on weekly plasma glucose, NEFA, or lactate, rumen fluid pH, or glucose peak concentration, plateau, and rate. These data indicate that increased propionate may decrease DMI and alter feeding behavior but might not be related to glucose metabolism.

Brown adipose tissue is the key depot for glucose clearance in microbiota depleted mice

Gut microbiota deficient mice demonstrate accelerated glucose clearance. However, which tissues are responsible for the upregulated glucose uptake remains unresolved, with different studies suggesting that browning of white adipose tissue, or modulated hepatic gluconeogenesis, may be related to enhanced glucose clearance when the gut microbiota is absent. Here, we investigate glucose uptake in 22 different tissues in 3 different mouse models. We find that gut microbiota depletion via treatment with antibiotic cocktails (ABX) promotes glucose uptake in brown adipose tissue (BAT) and cecum. Nevertheless, the adaptive thermogenesis and the expression of uncoupling protein 1 (UCP1) are dispensable for the increased glucose uptake and clearance. Deletion of Ucp1 expressing cells blunts the improvement of glucose clearance in ABX-treated mice. Our results indicate that BAT and cecum, but not white adipose tissue (WAT) or liver, contribute to the glucose uptake in the gut microbiota depleted mouse model and this response is dissociated from adaptive thermogenesis.

Glycocalyx engineering with heparan sulfate mimetics attenuates Wnt activity during adipogenesis to promote glucose uptake and metabolism.

Adipose tissue (AT) plays a crucial role in maintaining metabolic homeostasis by storing lipids and glucose from circulation as intracellular fat. As peripheral tissues like AT become insulin resistant, decompensation of blood glucose levels occurs causing type 2 diabetes (T2D). Currently, glycocalyx modulating as a pharmacological treatment strategy to improve glucose homeostasis in T2D patients is underexplored. Here, we show a novel role for cell surface heparan sulfate (HS) in establishing glucose uptake capacity and metabolic utilization in differentiated adipocytes. Using a combination of chemical and genetic interventions, we identified that HS modulates this metabolic phenotype by attenuating levels of Wnt signaling during adipogenesis. By engineering the glycocalyx of preadipocytes with exogenous synthetic HS mimetics, we were able to enhance glucose clearance capacity after differentiation through modulation of Wnt ligand availability. These findings establish the cellular glycocalyx as a possible new target for therapeutic intervention in T2D patients by enhancing glucose clearance capacity independent of insulin secretion.

Female Mice Are Protected from Metabolic Decline Associated with Lack of Skeletal Muscle HuR

Male mice lacking HuR in skeletal muscle (HuRm−/−) have been shown to have decreased gastrocnemius lipid oxidation and increased adiposity and insulin resistance. The same consequences have not been documented in female HuRm−/− mice. Here we examine this sexually dimorphic phenotype. HuRm−/− mice have an increased fat mass to lean mass ratio (FM/LM) relative to controls where food intake is similar. Increased body weight for male mice correlates with increased blood glucose during glucose tolerance tests (GTT), suggesting increased fat mass in male HuRm−/− mice as a driver of decreased glucose clearance. However, HuRm−/− female mice show decreased blood glucose levels during GTT relative to controls. HuRm−/− mice display decreased palmitate oxidation in skeletal muscle relative to controls. This difference is more robust for male HuRm−/− mice and more exaggerated for both sexes at high dietary fat. A high-fat diet stimulates expression of Pgc1α in HuRm−/− male skeletal muscle, but not in females. However, the lipid oxidation Pparα pathway remains decreased in HuRm−/− male mice relative to controls regardless of diet. This pathway is only decreased in female HuRm−/− mice fed high fat diet. A decreased capacity for lipid oxidation in skeletal muscle in the absence of HuR may thus be linked to decreased glucose clearance in male but not female mice.

Disruption of endothelial Pfkfb3 ameliorates diet-induced murine insulin resistance

Overnutrition-induced endothelial inflammation plays a crucial role in high fat diet (HFD)-induced insulin resistance in animals. Endothelial glycolysis plays a critical role in endothelial inflammation and proliferation, but its role in diet-induced endothelial inflammation and subsequent insulin resistance has not been elucidated. PFKFB3 is a critical glycolytic regulator, and its increased expression has been observed in adipose vascular endothelium of C57BL/6J mice fed with HFD in vivo, and in palmitate (PA)-treated primary human adipose microvascular endothelial cells (HAMECs) in vitro. We generated mice with Pfkfb3 deficiency selective for endothelial cells to examine the effect of endothelial Pfkfb3 in endothelial inflammation in metabolic organs and in the development of HFD-induced insulin resistance. EC Pfkfb3-deficient mice exhibited mitigated HFD-induced insulin resistance, including decreased body weight and fat mass, improved glucose clearance and insulin sensitivity, and alleviated adiposity and hepatic steatosis. Mechanistically, cultured PFKFB3 knockdown HAMECs showed decreased NF-κB activation induced by PA, and consequent suppressed adhesion molecule expression and monocyte adhesion. Taken together, these results demonstrate that increased endothelial PFKFB3 expression promotes diet-induced inflammatory responses and subsequent insulin resistance, suggesting that endothelial metabolic alteration plays an important role in the development of insulin resistance.

Metabolic Effects of pH Enhanced Ground Beef in Diet-induced Obese Mice

Objectives Western diets, characterized by higher amounts of saturated fats, fatty proteins, and lower consumption of fruits, vegetables and lean proteins (alkaline diet) has been suggested to contribute to metabolic diseases (e.g., obesity), through low-grade metabolic acidosis (low pH). Hence, our objective was to test the effects of diets rich in beef prepared at various pH levels, in diet induced obese B6 mice. We hypothesized that metabolic health will be improved by consuming a diet containing pH-enhanced cooked ground beef, compared to a non pH-enhanced beef diet. Methods B6 male and female mice were randomized (n = 5) into 6 groups; low fat (LF), pH-enhanced (ammonia) LF (LFN), high fat (HF), pH-enhanced HF (HFN), HF with beef (HFB), pH-enhanced HF beef (HFBN). Weight gain and food intake were measured weekly (for 12 weeks) and a glucose tolerance test (GTT) was performed at week 10. Tissues, including white adipose tissue (WAT) and liver were collected and used for histology, RNA and protein isolation, followed by analyses of gene (qRT-PCR) and proteins (Western blotting) related to fat and glucose metabolism. Results Final body weight was significantly higher in HF group compared to LF and LFN groups in males, but not in females. Moreover, glucose clearance was significantly better in LF groups compared to HF group for both male and females. Interestingly, pH enhanced groups (HFN and HFBN) demonstrated significantly improved glucose clearance at the end of GTT compared to HF group only in males. Male WAT had smaller fat cell size, and greater fat cell number (P < 0.05) in HFN and HFBN compared to HF and HFB respectively. HFBN showed less hepatic fat accumulation in male mice compared to HFB group. Corroborating these, mRNA level of fatty acid oxidation marker Cpt1α was upregulated in HFBN group compared to HFB (P value 0.07) in male liver. Conclusions Findings from this HF diet-induced obesity research suggest that there are potential metabolic benefits of increased dietary pH, through improved glucose clearance and fat metabolism. However, additional research is warranted to determine the underlying mechanisms and whether similar effects will be observed with LF pH-enhanced beef diets. These results can be further translated to human subjects to understand interactions between beef, pH and fat content on metabolic diseases. Funding Sources Empirical Foods, Inc.