Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme for NAD salvage and the abundance of Nampt has been shown to be altered in non-alcoholic fatty liver disease. It is, however, unknown how hepatic Nampt is regulated in response to accumulation of lipids in the liver of mice fed a high-fat diet (HFD). HFD mice gained more weight, stored more hepatic lipids and had an impaired glucose tolerance compared with control mice. NAD levels as well as Nampt mRNA expression, protein abundance and activity were significantly increased in HFD mice. Enhanced NAD levels were associated with deacetylation of p53 and Nfκb indicating increased activation of Sirt1. Despite impaired glucose tolerance and increased hepatic lipid levels in HFD mice, NAD metabolism was significantly enhanced. Thus, improved NAD metabolism may be a compensatory mechanism to protect against negative impact of hepatic lipid accumulation.

No description available.

This study investigated the effect of high-fat diet consumption on Alzheimer's disease-related pathology in the Tg6799 mouse model. We found that high-fat diet attenuates Alzheimer's disease-related pathology and cognitive dysfunction in Tg6799 mice and propose decreased beta-amyloid deposition due to improved autophagic-lysosomal flux as a potential, underlying mechanism.

Background: The number of cancer survivors across North America is increasing, with estimates indicating that this population will grow to nearly 19 million individuals by the end of 2020. This increase can be attributed, in part, due to improvements in cancer treatments, of which radiation therapy is most commonly used. Unfortunately, exposure to radiation also increases the risk of secondary cancer development long-term. Moreover, obesity and physical inactivity are prevalent, modifiable, risk factors among cancer survivors, with both factors being linked to decrements in quality of life, increased cancer risk, and greater mortality risk. To date, there has been promising epidemiological and clinical data highlighting the role of exercise as a way to mitigate cancer risk and improve survival; however, longitudinal studies are lacking and the effects of radiation in these studies have been largely ignored. Therefore, there is a major clinical need to directly evaluate the combinatory long-term effects of radiation, exercise, and/or obesity to reveal their implications on healthspan, cancer incidence, and survival. Recent pre-clinical work from our group has shown that after being exposed to radiation, endurance exercise prevented several negative alterations to hematopoietic stem cells and their niche caused by high-fat diet (HFD)-induced obesity. We also showed that leukemic blast viability in vitro was greater when cultured in bone marrow supernatant from mice with HFD-induced obesity compared to bone marrow supernatant from mice without HFD-induced obesity. It is unknown, however, whether these findings extend to alterations in cancer risk across the lifespan. As such, the purpose of this study was to evaluate the effects of lifelong exercise and diet-induced obesity on healthspan, cancer incidence, and survival in an established mouse model of radiation-induced cancer. Methods: Male CBA mice (n=80) were randomly divided into either a control diet (CTRL; n=40) of 45% high-fat diet (HFD; n=40) and then further divided into either a sedentary group (SED; n=20) or exercise-trained group (EX; n=20). At age 13 weeks, all mice were exposed to a cancer inducing dose of whole-body ionizing radiation (3 Gy). A healthspan index score and endpoint monitoring were conducted throughout the study by blinded investigators. Results: When normalized to CTRL/SED, the highest healthspan score was in the CTRL/EX (score = +2.5), followed by HFD/EX (score = +1) and lastly HFD/SED (score = -0.5). Cancer incidence was significantly higher in the HFD/SED group when compared to the CTRL/EX group (p<0.05) and a trend for higher cancer incidence for HFD/SED was observed when compared to the CTRL/SED group (p=0.079). There was no significant difference between the HFD/SED and HFD/EX group in cancer incidence (p>0.05). Overall survival was significantly higher in the HFD/SED group compared to CTRL/SED group (p<0.05); however, risk of cancer-related mortality was 1.6-times higher in the HFD/SED group compared to the CTRL/SED group (RR=1.60; 95% CI, 1.00-2.56; p=0.0495) and 1.68-times that of the CTRL/EX group (RR=1.68; 95% CI, 1.02-2.78; p=0.0415). Conclusion: Our findings show that lifelong exercise training resulted in higher healthspan index, lower cancer incidence, and lower risk of cancer-related mortality following radiation exposure, with these effects being largely reversed by HFD-induced obesity. This study provides the rationale for future studies to uncover cellular and molecular mechanisms that could be underlying these results. Moreover, this study presents a proof of concept for the consideration of clinical studies in cancer survivors examining exercise as an intervention to reduce the long-term effects of radiation.

B1 B cells have received increasing attention recently due to their newly discovered phagocytic and microbicidal capabilities. Several studies have demonstrated that B1 cells can phagocytize polystyrene fluorescent particles, bacteria (Staphylococcus aureus, Escherichia coli), and even apoptotic cells. Nevertheless, little is known about the biological significance of this seemingly redundant function of B1 B cells as compared to that of conventional phagocytes. Here we investigate the unique phosphotidylcholine (PtC)-specific B1 B cell phagocytosis. PtC is a major phospholipid in the biological membrane and a classical antigen recognized by B1 B cell-derived natural antibodies. These antibodies play important roles in immune defense as well as tissue homeostasis. Here we report that B1 cells preferentially phagocytose PtC-coated beads, differing from that of conventional macrophages. We further attest that these beads were truly internalized and subsequently fused with hydrolytic lysosomes indicated by increasing fluorescent intensity of a pH-sensitive dye. Despite the differences in antigen specificity, phagocytosis of both B1 cells and macrophages can be inhibited by the microtubule-inhibitor, Colchicine, in a dose-dependent manner. Most intriguingly, upon chronic high-fat diet (HFD) consumption by the host, B1 cell phagocytosis starts to lose antigen-specificity for PtC. Morphologically, some of these B1 B cells in DIO mice show enlarged cytosol and engulfed more beads, indicating a transition to macrophage-like cells. Our study suggests for the first time that B1 B cells have unique phospholipid-specific phagocytosis capacity, which is affected by diet-induced obesity.

Indiana University-Purdue University Indianapolis (IUPUI) / Insulin resistance in liver, muscle, and adipose tissue almost invariably occurs during obesity. To compensate, the insulin-producing β-cell increases insulin production by expanding cellular mass. The inability of the β-cell to fully compensate leads to hyperglycemia and ultimately type 2 diabetes. The enzyme deoxyhypusine synthase (DHS) catalyzes the spermidine-dependent posttranslational modification of Lys50 of eukaryotic translation initiation factor 5A (eIF5A) to form hypusine (Hyp). Studies have demonstrated this modification of eIF5A to contribute to cellular proliferation in cancerous cells, but its role in the physiologic proliferation of islet β-cells is unknown. I hypothesized eIF5A-Hyp to be required for the proliferation of islet β cells during the early phase of insulin resistance, allowing the β-cell to respond to the increased demand for insulin to maintain glucose homeostasis. To test this hypothesis, deletion of DHS was induced post-developmentally in β-cells by crossing Dhs-fl/fl mice with MIP1-CreERT mice, and animals were fed for 1 or 4 weeks with a 60% kcal from fat diet (HFD) or normal chow diet (NCD, 16% kcal from fat diet). NCD-fed and HFD-fed animals had normal glucose homeostasis after one week feeding, regardless of genotype. However, after 4 weeks of HFD, KO mice had significantly worse glucose intolerance compared to control mice. eIF5A-Hyp levels increased in β-cells of control animals and as expected remained low in the KO mice. β-cell proliferation was significantly increased after 1 week of HFD as measured by PCNA staining, however KO mice showed no increase. Cyclin D2 protein, but not mRNA, was increased in control animals fed a HFD; this protein increase was not observed in KO animals. Furthermore, polyribosomal profile of isolated islets of 1 week HFD-fed mice showed the Ccnd2 mRNA bound to the monoribosome fractions in the KO animals compared to the controls, resulting in changes of global translation. Interestingly, Ccnd1 polyribosome to monoribosome ratio showed no changes in translation compared to Ccnd2. Taken together, these results suggest that DHS (and, consequently, eIF5A-Hyp) is necessary for the adaptive proliferative and functional response of β-cells during high fat diet induced obesity and glucose intolerance.

No description available.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24795号 / 医博第4987号 / 新制||医||1066(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 小林 恭, 教授 波多野 悦朗, 教授 羽賀 博典 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

<p>  </p> <p>In modern society, continuous light exposure and obesity are increasingly prevalent, especially in women of childbearing age. Circadian, metabolic, and reproductive systems have a complex, inter-regulated relationship. Thus, the disruption of one system likely impedes another. Excessive adiposity and circadian disruption alter normal behavior and physiology and disrupt the endocrine milieu. The overall goal of the studies described in this thesis was to develop and test a model system that could tease apart the influence of prepregnancy obesity and circadian disruption, as well as study the combined effects on female reproductive competence. </p> <p>The first study focuses on the prepregnancy period and aims to determine the effect of high fat diet feeding on diurnal eating pattern, body weight over the four-week period, the body composition at the end of the four-week period, hair corticosterone levels, and circadian fecal corticosterone patterns on female ICR mice. Five-week-old female ICR mice were randomly assigned to control (CON; 10% fat) or high fat (HF; 60%) diets and fed for four weeks to achieve adequate adiposity. During this four-week time period, mice had routine light exposure of 12h light and 12h dark. Feed was weighed at 0600 and 1745 Monday-Friday to determine diurnal feed intake. The mice were weighed on a weekly basis. After four weeks on respective diets, mice were anesthetized with isoflurane to measure crown-rump length to calculate BMI and hair was shaved for corticosterone extraction. Once mice recovered from anesthesia, body composition was measured with EchoMRI. After 1 week on diets, HF mice consumed more (P<0.05) during the day than CON mice, which is typically when mice are inactive. After two weeks on diets, HF mice weighed more (P<0.05) than CON, as well as had higher BMI and percent body fat (P<0.05) than CON after four weeks on diets. After four weeks on diets, HF mice had high hair corticosterone (P<0.05). Sampling feces over a 48h period at the end of the four weeks demonstrated that HF mice had elevated basal corticosterone, attenuated circadian rhythms, and a shift in corticosterone amplitude. The prepregnancy period demonstrated that high fat diets alone alter circadian eating pattern and corticosterone rhythms.</p> <p>The remainder of the study continued the dietary treatments assigned during the prepregnancy period, as well as implemented light conditions to create a 2Χ3 factorial study design. There were three light conditions: 12h light and 12h dark (LD), 24h dim light (L5), or 24h bright light (L100). Mice were moved into experimental light conditions after the observation of a vaginal plug or after 5 days with males. This portion of the study aimed to determine the effect of diet (CON or HF) and light exposure (LD, L5, or L100) on gestation length, number of pups born, milk composition, litter weight on postnatal day 12, as well as dam feed intake, hair corticosterone levels, and plasma prolactin. Continuous light exposure increased gestation length, with L5 (19.1 d ± 0.23) and L100 (18.9 d ± 0.21) having longer gestation lengths (P<0.05) than LD (18.1 d ± 0.25). Diet affected the number of pups born (P<0.05), with HF dams having fewer pups (9.99 ± 0.4) than CON (11.4 ± 0.4). Despite no difference in birth weight of standardized litters (n=8 pus/litter), litters of HF dams weighed more than CON by day 4 postnatal. The greater litter weight of HF dams continued until the end of the study on day 12 of lactation (P<0.05). Light had a tendency to increase litter weight (P=0.07). Diet, light, and stage of reproduction influenced dam feed intake (P<0.05). L100 dams had higher plasma prolactin, as well as final dam and mammary wet weights (P<0.05). Constant light exposure decreased ATP content in the mammary gland (P<0.05) and decreased milk lactose concentration (P<0.05). Pearson’s correlation analysis showed a positive relationship between mammary weight, fat pad weight, BMI, kcal of feed intake, and gestation length (P<0.05). In CON mice, hair corticosterone was negatively correlated with litter weight on lactation day 12. Liver weight was positively correlated with d 12 litter weight in HF mice. Together, these studies demonstrate that feeding high fat diets and continuous light alter maternal behavior and physiology, which may impact offspring health and development, however continuous light may not be the best approach to studying circadian disruption. Elevated maternal plasma prolactin and increased dam weight suggests a long day photoperiod was likely induced, thus potentially mitigating the circadian disruptive effects from constant light. Other model systems should be considered, such as using a chronic jet lag model that changes the light exposure every 3 d. </p>

This study investigated the effects of daily consumption of Thompson seedless raisins on markers of inflammation, oxidative stress and endothelial activation in response to an acute high-fat meal in obese individuals. Seventeen overweight men and women consumed raisins or placebo (264 kcal/d) for 14 d in a randomized cross-over design while following a low-flavonoid, weight-maintenance diet. Four high-fat (53% fat) meals were consumed with the respective treatment pre and post interventions. Measures at fasting, and 2, 3 and 4 hours postprandial included markers of oxidative stress (urinary 8-isoPGF2α; serum Oxygen Radical Absorbance Capacity, ORAC), inflammation (serum C-reactive protein, CRP; interleukin-6, IL-6), endothelial function (serum soluble intercellular adhesion molecule-1, sICAM-1; soluble vascular adhesion molecule-1, sVCAM-1), and metabolic measures (free fatty acids (FFA), triacylglycerol (TAC), glucose, insulin). Urinary 8-isoPGF2α decreased 22% and ORAC increased 3% pre to post interventions combined. Postprandial metabolic responses differed by gender, males surpassed females for several measures: FFA, triacylglycerol, glucose, and sVCAM-1. Neither the meals nor treatment with raisins had any noteworthy influence on fasted measures of inflammation or endothelial dysfunction. Acute high fat meal consumption did not result in evidence of inflammation or oxidative stress in these relatively healthy, overweight individuals. Providing all food in regular pattern reduced measures of oxidative stress. Gender influenced metabolic responses to meals; males had a greater postprandial response in metabolic measures than females. / Master of Science