Epidemiological literature indicates that women are less susceptible to type II diabetes (T2D) than males. The general consensus is that estrogen is protective, whereas its deficiency in ...post-menopause is associated with adiposity and impaired insulin sensitivity. However, epidemiological data suggests that males are more prone to developing T2D, and at a lower BMI, compared to females during post-menopausal years; suggesting that another factor, other than estrogen, protects females. We proposed to determine if adiponectin (APN) serves as this protective factor. An initial experiment was performed in which gonadally intact male and female mice were fed either a purified low-fat diet (LFD) or high-fat diet (HFD) (40% kcals from fat) for 16 weeks. An additional group of HFD ovariectomy (OVX) mice were included to assess estrogen deficiency's impact on obesity. Body composition, adipose tissue inflammation, ectopic lipid accumulation as well as glucose metabolism and insulin resistance were assessed. In corroboration with previous data, estrogen deficiency (OVX) exacerbated HFD-induced obesity in female mice. However, despite a higher body fat percentage and a similar degree of hepatic and skeletal muscle lipid accumulation, female OVX HFD-fed mice exhibited enhanced insulin sensitivity relative to HFD-fed males. Therefore, a subsequent HFD experiment was performed utilizing male and female (both gonadally intact and OVX) APN deficient mice (APN
) and wildtype littermates to determine if APN is the factor which protects OVX females from the similar degree of metabolic dysfunction as males in the setting of obesity. Indirect calorimetry was used to determine observed phenotype differences. APN deficiency limited adiposity and mitigated HFD-induced insulin resistance and adipose tissue inflammation in gonadally intact male and female, but not in OVX mice. Using indirect calorimetry, we uncovered that slight, but non-statistically significant differences in food intake and energy expenditure leading to a net difference in energy balance likely explain the reduced body weight exhibited by male APN-deficient mice. In conclusion, congenital APN deficiency is protective against obesity development in gonadally intact mice, however, in the setting of estrogen deficiency (OVX) this is not true. These findings suggest that gonadal status dictates the protective effects of congenital APN deficiency in the setting of HFD-induced obesity.
Fluorouracil/5-flourouracil (5FU) is a first-line chemotherapy drug for many cancer types; however, its associated toxicities contribute to poor quality of life and reduced dose intensities ...negatively impacting patient prognosis. While obesity remains a critical risk factor for most cancers, our understanding regarding how obesity may impact chemotherapy's toxicities is extremely limited. C56BL/6 mice were given high fat (Obese) or standard diets (Lean) for 4 months and then subjected to three cycles of 5FU (5d-40 mg/kg Lean Mass, 9d rest) or PBS vehicle control. Shockingly, only 60% of Obese survived 3 cycles compared to 100% of Lean, and Obese lost significantly more body weight. Dihydropyrimidine dehydrogenase (DPD), the enzyme responsible for 5FU catabolism, was reduced in obese livers. Total white blood cells, neutrophils, and lymphocytes were reduced in Obese 5FU compared to Lean 5FU and PBS controls. While adipocyte size was not affected by 5FU in Obese, skeletal muscle mass and myofibrillar cross section area were decreased following 5FU in Lean and Obese. Although adipose tissue inflammatory gene expression was not impacted by 5FU, distinct perturbations to skeletal muscle inflammatory gene expression and immune cell populations (CD45
+
Immune cells, CD45
+
CD11b
+
CD68
+
macrophages and CD45
+
CD11b
+
Ly6c
lo/int
macrophage/monocytes) were observed in Obese only. Our evidence suggests that obesity induced liver pathologies and reduced DPD exacerbated 5FU toxicities. While obesity has been suggested to protect against cancer/chemotherapy-induced cachexia and other toxicities, our results demonstrate that obese mice are not protected, but rather show evidence of increased susceptibility to 5FU-induced cytotoxicity even when dosed for relative lean mass.
Abstract
Aims
The role of skeletal muscle estrogen and its ability to mitigate the negative impact of a high-fat diet (HFD) on obesity-associated metabolic impairments is unknown. To address this, we ...developed a novel mouse model to determine the role of endogenous 17β-estradiol (E2) production in males in skeletal muscle via inducible, skeletal muscle–specific aromatase overexpression (SkM-Arom↑).
Methods
Male SkM-Arom↑ mice and littermate controls were fed a HFD for 14 weeks prior to induction of SkM-Arom↑ for a period of 6.5 weeks. Glucose tolerance, insulin action, adipose tissue inflammation, and body composition were assessed. Indirect calorimetry and behavioral phenotyping experiments were performed using metabolic cages. Liquid chromatography mass spectrometry was used to determine circulating and tissue (skeletal muscle, hepatic, and adipose) E2 and testosterone concentrations.
Results
SkM-Arom↑ significantly increased E2 in skeletal muscle, circulation, the liver, and adipose tissue. SkM-Arom↑ ameliorated HFD-induced hyperglycemia, hyperinsulinemia, impaired glucose tolerance, adipose tissue inflammation, and reduced hepatic lipid accumulation while eliciting skeletal muscle hypertrophy.
Conclusion
Enhanced skeletal muscle aromatase activity in male mice induces weight loss, improves metabolic and inflammatory outcomes and mitigates the negative effects of a HFD. Additionally, our data demonstrate for the first time skeletal muscle E2 has anabolic effects on the musculoskeletal system.
This paper investigates the electrothermal stability and the predominant defect mechanism of a Schottky gate AlGaN/GaN HEMT. Calibrated 3-D electrothermal simulations are performed using a simple ...semiempirical dc model, which is verified against high-temperature measurements up to 440°C. To determine the thermal limits of the safe operating area, measurements up to destruction are conducted at different operating points. The predominant failure mechanism is identified to be hot-spot formation and subsequent thermal runaway, induced by large drain-gate leakage currents that occur at high temperatures. The simulation results and the high temperature measurements confirm the observed failure patterns.
The pro‐inflammatory cytokine, tumor necrosis factor‐alpha (TNF‐α), has been suggested to be a key factor in the induction of obesity‐associated metabolic dysfunction. However, the role that ...macrophage‐derived TNF‐α has on regulating metabolic perturbations in obesity is not completely understood. Therefore, we utilized the TNF‐αFlox/Flox (F/F), LyzMcre± mouse model to determine the impact that macrophage TNF‐α deletion has on the development of high‐fat diet (HFD)‐induced obesity. At 10 weeks of age, male littermates were randomly assigned to 1 of 4 groups: TNF‐αF/F low‐fat diet (TNF‐αF/F LFD), TNF‐αF/F, LyzMCre LFD, TNF‐αF/F HFD, or TNF‐αF/F, LyzMCre HFD (n = 16‐28/group) and were fed their respective diets for 18 weeks. Body weight was assessed throughout the course of the experiment. Body composition, hepatic lipid accumulation, and metabolic outcomes were also examined. A microarray gene expression experiment was performed from RNA isolated from epididymal adipose tissue of the HFD‐fed groups (n = 10/group) and results were verified via qRT‐PCR for all groups. Macrophage‐derived TNF‐α deletion significantly reduced adipose tissue TNF‐α gene expression and circulating TNF‐α and downregulated genes linked to the toll‐like receptor (TLR) and NFκB signaling pathways. However, macrophage TNF‐α deletion had no effect on hindering the development of obesity, hepatic lipid accumulation, or improving glucose metabolism or insulin sensitivity. In conclusion, macrophage‐derived TNF‐α is not a causative factor for the induction of obesity‐associated metabolic dysfunction.
•Vivarium temperature (temp) fluctuates on a monthly, daily, and even hourly basis.•Fluctuations in vivarium temp impedes scientific reproducibility.•5ºC ∆ in vivarium temp impacts total and resting ...energy expenditure 27–39%.•5ºC ∆ in vivarium temp impacts physical activity, food intake and sleep 13–50%.
The purpose of this investigation was to examine the variability in vivarium temperature and the impact that this has on metabolic and behavioral outcomes in mice.
Daily vivarium temperature was monitored every day for a two-year period. Behavioral and metabolic phenotyping were assessed in male and female C57BL/6 (n = 71/sex) mice over the course of 2 years.
Vivarium temperature was found to fluctuate on a monthly, daily, and even an hourly basis of approximately ±5ºC. A 5ºC change in temperature was found to result in daily changes in total energy expenditure (35% and 27%), resting energy expenditure (39% for both sexes), movement (51% and 37%), food consumption (35% and 29%), and sleep duration (15% and 13%) for female and male mice, respectively.
Fluctuations in vivarium temperature can dramatically impact metabolic and behavioral outcomes, which impedes scientific reproducibility. This awareness and the guidelines we propose in this publication will hopefully help to enhance the reproducibility of pre-clinical animal research.
Abstract
Aims
We developed a novel mouse model with increased skeletal muscle estrogen content via inducible, skeletal-muscle–specific aromatase overexpression (SkM-Arom↑). We proposed to examine the ...effect that increased skeletal muscle estrogen both in gonadally intact and ovariectomized (OVX) female mice has on preventing or rescuing high-fat diet (HFD)-induced obesity.
Methods
In the prevention experiment, gonadally intact and OVX SkM-Arom↑ mice and littermate controls were fed a low-fat diet (LFD) or HFD for 13 weeks. SkM-Arom↑ was induced at the initiation of dietary treatment. In the intervention experiment, gonadally intact and OVX SkM-Arom↑ mice and littermate controls were fed an HFD for 14 weeks before induction of SkM-Arom↑ for 6 weeks. Glucose tolerance, insulin action, adipose tissue inflammation, and body composition were assessed. Liquid chromatography–mass spectrometry was used to determine circulating and skeletal muscle steroid content.
Results
SkM-Arom↑ significantly increased skeletal muscle 17β-estradiol (E2) and estrone (E1) in both experiments. Interestingly, this resulted in leakage of estrogens into circulation, producing a physiologically relevant E2 concentration. Consequently, bone mineral density (BMD) was enhanced and adipose tissue inflammation was reduced in the prevention experiment only. However, no benefits were seen with respect to changes in adiposity or metabolic outcomes.
Conclusion
We show that increasing skeletal muscle estrogen content does not provide a metabolic benefit in gonadally intact and OVX female mice in the setting of obesity. However, a chronic physiological concentration of circulating E2 can improve BMD and reduce adipose tissue inflammation independently of a metabolic benefit or changes in adiposity.
Synthetic mRNA transfection enables efficient and controlled gene expression in human cells, without genome integrations. Further, modifications to the mRNA and transfection protocol now allow for ...repeated transfection and long-term gene expression of an otherwise short-lived mRNA expression. This is mainly achieved through introducing modified nucleosides and interferon suppression. In this study we provide an overview and details of the advanced synthesis and modifications of mRNA originally developed for reprogramming. This mRNA allows for very efficient transfection of fibroblasts enabling the generation of high quality human iPS cells with a six-factor mRNA cocktail in 9 days. Furthermore, we synthesised and transfected modified MYOD1 mRNA to transdifferentiate human fibroblasts into myoblast-like cells without a transgene footprint. This efficient and integration-free mRNA technology opens the door for safe and controlled gene expression to reverse or redirect cell fate.
Serum sex steroid levels fluctuate throughout the reproductive cycle. However, the degree to which sex steroid tissue content mimics circulating content is unknown. Understanding the flux and ...physiological quantity of tissue steroid content is imperative for targeted hormonal therapy development. Utilizing a gold-standard ultrasensitive liquid chromatography-mass spectrometry (LC/MS) method we determined sex steroid (17β-estradiol E2, testosterone, androstenedione, and progesterone) fluctuations in serum and in 15 tissues throughout the murine estrous cycle (proestrus, estrus, and diestrus I) and in ovariectomized (OVX) mice. We observed dynamic fluctuations in serum and tissue steroid content throughout the estrous cycle with proestrus generally presenting the highest content of E2, testosterone, and androstenedione, and lowest content of progesterone. In general, the trend in circulating steroid content between the stages of the estrous cycle was mimicked in tissue. However, the absolute amounts of steroid levels when normalized to tissue weight were found to be significantly different between the tissues with the serum steroid quantity often being significantly lower than the tissue quantity. Additionally, we found that OVX mice generally displayed a depletion of all steroids in the various tissues assessed, except in the adrenal glands which were determined to be the main site of peripheral E2 production after ovary removal. This investigation provides a comprehensive analysis of steroid content throughout the estrous cycle in a multitude of tissues and serum. We believe this information will help serve as the basis for the development of physiologically relevant, tissue-specific hormonal therapies.
Cachexia, a complex wasting syndrome, significantly affects the quality of life and treatment options for cancer patients. Studies have reported a strong correlation between high platelet count and ...decreased survival in cachectic individuals. Therefore, this study aimed to investigate the immunopathogenesis of cancer cachexia using the Apc
Min/+
mouse model of spontaneous colorectal cancer. The research focused on identifying cellular elements in the blood at different stages of cancer cachexia, assessing inflammatory markers and fibrogenic factors in the skeletal muscle, and studying the behavioral and metabolic phenotype of Apc
Min/+
mice at the pre-cachectic and severely cachectic stages. Platelet measurements were also obtained from other animal models of cancer cachexia - Lewis Lung Carcinoma and Colon 26 adenocarcinoma. Our study revealed that platelet number is elevated prior to cachexia development in Apc
Min/+
mice and can become activated during its progression. We also observed increased expression of TGFβ2, TGFβ3, and SMAD3 in the skeletal muscle of pre-cachectic Apc
Min/+
mice. In severely cachectic mice, we observed an increase in Ly6g, CD206, and IL-10 mRNA. Meanwhile, IL-1β gene expression was elevated in the pre-cachectic stage. Our behavioral and metabolic phenotyping results indicate that pre-cachectic Apc
Min/+
mice exhibit decreased physical activity. Additionally, we found an increase in anemia at pre-cachectic and severely cachectic stages. These findings highlight the altered platelet status during early and late stages of cachexia and provide a basis for further investigation of platelets in the field of cancer cachexia.
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