Characteristics of Nutrition and Metabolism in Dogs and Cats

Domestic dogs and cats have evolved differentially in some aspects of nutrition, metabolism, chemical sensing, and feeding behavior. The dogs have adapted to omnivorous diets containing taurine-abundant meat and starch-rich plant ingredients. By contrast, domestic cats must consume animal-sourced foods for survival, growth, and development. Both dogs and cats synthesize vitamin C and many amino acids (AAs, such as alanine, asparagine, aspartate, glutamate, glutamine, glycine, proline, and serine), but have a limited ability to form de novo arginine and vitamin D3. Compared with dogs, cats have greater endogenous nitrogen losses and higher dietary requirements for AAs (particularly arginine, taurine, and tyrosine), B-complex vitamins (niacin, thiamin, folate, and biotin), and choline; exhibit greater rates of gluconeogenesis; are less sensitive to AA imbalances and antagonism; are more capable of concentrating urine through renal reabsorption of water; and cannot tolerate high levels of dietary starch due to limited pancreatic α-amylase activity. In addition, dogs can form sufficient taurine from cysteine (for most breeds); arachidonic acid from linoleic acid; eicosapentaenoic acid and docosahexaenoic acid from α-linolenic acid; all-trans-retinol from β-carotene; and niacin from tryptophan. These synthetic pathways, however, are either absent or limited in all cats due to (a) no or low activities of key enzymes (including pyrroline-5-carboxylate synthase, cysteine dioxygenase, ∆6-desaturase, β-carotene dioxygenase, and quinolinate phosphoribosyltransferase) and (b) diversion of intermediates to other metabolic pathways. Dogs can thrive on one large meal daily, select high-fat over low-fat diets, and consume sweet substances. By contrast, cats eat more frequently during light and dark periods, select high-protein over low-protein diets, refuse dry food, enjoy a consistent diet, and cannot taste sweetness. This knowledge guides the feeding and care of dogs and cats, as well as the manufacturing of their foods. As abundant sources of essential nutrients, animal-derived foodstuffs play important roles in optimizing the growth, development, and health of the companion animals.

Roles of Nutrients in the Brain Development, Cognitive Function, and Mood of Dogs and Cats

The brain is the central commander of all physical activities and the expression of emotions in animals. Its development and cognitive health critically depend on the neural network that consists of neurons, glial cells (namely, non-neuronal cells), and neurotransmitters (communicators between neurons). The latter include proteinogenic amino acids (e.g., L-glutamate, L-aspartate, and glycine) and their metabolites [e.g., γ-aminobutyrate, D-aspartate, D-serine, nitric oxide, carbon monoxide, hydrogen sulfide, and monoamines (e.g., dopamine, norepinephrine, epinephrine, and serotonin)]. In addition, some non-neurotransmitter metabolites of amino acids, such as taurine, creatine, and carnosine, also play important roles in brain development, cognitive health, behavior, and mood of dogs and cats. Much evidence shows that cats require dietary ω3 (α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid) and ω6 (linoleic acid and arachidonic acid) polyunsaturated fatty acids for the development of the central nervous system. As an essential component of membranes of neurons and glial cells, cholesterol is also crucial for cognitive development and function. In addition, vitamins and minerals are required for the metabolism of AAs, lipids, and glucose in the nervous system, and also act as antioxidants. Thus, inadequate nutrition will lead to mood disorders. Some amino acids (e.g., arginine, glycine, methionine, serine, taurine, tryptophan, and tyrosine) can help to alleviate behavioral and mood disorders (e.g., depression, anxiety and aggression). As abundant providers of all these functional amino acids and lipids, animal-sourced foods (e.g., liver, intestinal mucosa, and meat) play important roles in brain development, cognitive function, and mood of dogs and cats. This may explain, in part, why dogs and cats prefer to eat visceral organs of their prey. Adequate provision of nutrients in all phases of the life cycle (pregnancy, lactation, postnatal growth, and adulthood) is essential for optimizing neurological health, while preventing cognitive dysfunction and abnormal behavior.

Analysis of Gizzerosine in Foodstuffs by HPLC Involving Pre-column Derivatization with o-Phthaldialdehyde

Gizzerosine [2-amino-9-(4-imidazolyl)-7-azanonanoic acid] is a toxic amino acid formed from histamine and lysine at high temperatures, and may be present in foodstuffs (e.g., fishmeal and meat-bone meal) for animals including cats and dogs. Here we developed a simple, rapid, sensitive, specific, and automated method for the analysis of gizzerosine in foodstuffs by high-performance liquid chromatography (HPLC) involving pre-column derivatization with o-phthaldialdehyde (OPA) in the presence of N-acetylcysteine (instead of the usual 2-mercaptoethanol or ethanethiol reagent). OPA reacted immediately (within 1 min) with gizzerosine in an autosampler at room temperatures (e.g., 20-25 °C), and their derivative was directly injected into the HPLC column. The highly fluorescent gizzerosine-OPA derivative was well separated from the OPA derivatives of all natural amino acids known to be present in physiological fluids (e.g., plasma), proteins and foodstuffs, and was detected at an excitation wavelength of 340 nm and an emission wavelength of 450 nm. The total time for chromatographic separation (including column regeneration) was 20 min per sample rather than 40 min and longer in previous HPLC methods. The detection limit for gizzerosine was at least 6 pmol/ml in an assay solution (HPLC vial) or at least 0.09 pmol per injection into the HPLC column. The analysis of gizzerosine was linear between 1 and 100 pmol per injection. When gizzerosine was extracted from foodstuffs, its detection limit was at least 875 pmol/g foodstuff or at least 0.21 mg/kg foodstuff. Our routine HPLC technique does not require any cleanup of samples or the OPA derivatization products (including the OPA-gizzerosine adduct), and is applicable for the analysis of gizzerosine in both foodstuffs and animal tissues.

Clonal hematopoiesis related TET2 loss-of-function impedes IL1β-mediated epigenetic reprogramming in hematopoietic stem and progenitor cells

Clonal hematopoiesis (CH) is defined as a single hematopoietic stem/progenitor cell (HSPC) gaining selective advantage over a broader range of HSPCs. When linked to somatic mutations in myeloid malignancy-associated genes, such as TET2-mediated clonal hematopoiesis of indeterminate potential or CHIP, it represents increased risk for hematological malignancies and cardiovascular disease. IL1β is elevated in patients with CHIP, however, its effect is not well understood. Here we show that IL1β promotes expansion of pro-inflammatory monocytes/macrophages, coinciding with a failure in the demethylation of lymphoid and erythroid lineage associated enhancers and transcription factor binding sites, in a mouse model of CHIP with hematopoietic-cell-specific deletion of Tet2. DNA-methylation is significantly lost in wild type HSPCs upon IL1β administration, which is resisted by Tet2-deficient HSPCs, and thus IL1β enhances the self-renewing ability of Tet2-deficient HSPCs by upregulating genes associated with self-renewal and by resisting demethylation of transcription factor binding sites related to terminal differentiation. Using aged mouse models and human progenitors, we demonstrate that targeting IL1 signaling could represent an early intervention strategy in preleukemic disorders. In summary, our results show that Tet2 is an important mediator of an IL1β-promoted epigenetic program to maintain the fine balance between self-renewal and lineage differentiation during hematopoiesis.

Roxadustat protects rat renal tubular epithelial cells from hypoxia-induced injury through the TGF-β1/Smad3 signaling pathway

OBJECTIVE

Roxadustat is used to treat renal anemia. The renoprotective effect of roxadustat needs to be further confirmed, and the mechanism of action is unknown. This study aims to evaluate the effect and mechanism of roxadustat in hypoxia-related nephropathy with the renal tubular epithelial cell line NRK-52E.

MATERIALS AND METHODS

The cell Counting Kit-8 (CCK-8) assay was employed to assess cellular proliferation in the current investigation. Flow cytometry was used to conduct cell apoptosis analysis. The utilization of electron microscopy facilitated the identification of changes in cellular ultrastructure. Immunofluorescence was used to detect the expression trend of hypoxia-inducible factor-1α (HIF-1α). The connective tissue growth factor (CTGF), transforming growth factor-β1 (TGF-β1), Smad family member 3 (Smad3), p-Smad3, α-smooth muscle actin (α-SMA), collagen I, and HIF-1α were assessed by western blotting. Real-time fluorescent quantitative PCR (RT-qPCR) was used to measure TGF-β1 and Smad3 mRNA.

RESULTS

Significant growth inhibition and increased apoptosis were observed in NRK-52E cells cultured under hypoxic conditions (1% and 5% O2), which can be rescued by roxadustat. From a morphological perspective, it has been observed that roxadustat can counteract cellular damage features produced by hypoxia. These features include the contraction of the nuclear envelope and an increase in the formation of apoptotic bodies. Roxadustat increases HIF-1α expression acutely at 24 h, followed by a gradual reduction of HIF-1α expression to levels significantly below that of the hypoxia group by 72 h. Roxadustat can also inhibit hypoxia-induced increased expression of CTGF, TGF-β1, p-Smad3, α-SMA, collagen I, and HIF-1α. Combined treatment with roxadustat and siRNA against TGF-β1 synergistically reduced the expression of CTGF and HIF-1α, while the effect on TGF-β1 and p-Smad3 were comparable to that of the individual treatment alone. Comparably, the combined administration of roxadustat and siRNA targeting Smad3 had a synergistic impact on diminishing the expression of CTGF.

CONCLUSIONS

These findings indicate that roxadustat attenuates experimental renal fibrosis likely by inhibiting the TGF-β1/Smad3 pathways, while its effect on CTGF and HIF-1α may involve other signaling pathways.

Immunonutrition: facilitating mucosal immune response in teleost intestine with amino acids through oxidant-antioxidant balance

Comparative animal models generate fundamental scientific knowledge of immune responses. However, these studies typically are conducted in mammals because of their biochemical and physiological similarity to humans. Presently, there has been an interest in using teleost fish models to study intestinal immunology, particularly intestinal mucosa immune response. Instead of targeting the pathogen itself, a preferred approach for managing fish health is through nutrient supplementation, as it is noninvasive and less labor intensive than vaccine administrations while still modulating immune properties. Amino acids (AAs) regulate metabolic processes, oxidant-antioxidant balance, and physiological requirements to improve immune response. Thus, nutritionists can develop sustainable aquafeeds through AA supplementation to promote specific immune responses, including the intestinal mucosa immune system. We propose the use of dietary supplementation with functional AAs to improve immune response by discussing teleost fish immunology within the intestine and explore how oxidative burst is used as an immune defense mechanism. We evaluate immune components and immune responses in the intestine that use oxidant-antioxidant balance through potential selection of AAs and their metabolites to improve mucosal immune capacity and gut integrity. AAs are effective modulators of teleost gut immunity through oxidant-antioxidant balance. To incorporate nutrition as an immunoregulatory means in teleost, we must obtain more tools including genomic, proteomic, nutrition, immunology, and macrobiotic and metabonomic analyses, so that future studies can provide a more holistic understanding of the mucosal immune system in fish.

Regulation of synthesis of polyamines by progesterone, estradiol, and their receptors in uteri of cyclic ewes†

Progesterone (P4), estradiol (E2), and expression of their receptors (PGR and ESR1, respectively) by cells of the uterus regulate reproductive performance of mammals through effects on secretion and transport of nutrients into the uterine lumen. This study investigated the effect of changes in P4, E2, PGR, and ESR1 on expression of enzymes for the synthesis and secretion of polyamines. Suffolk ewes (n = 13) were synchronized to estrus (Day 0) and then, on either Day 1 (early metestrus), Day 9 (early diestrus), or Day 14 (late diestrus) of the estrous cycle, maternal blood samples were collected, and ewes were euthanized before obtaining uterine samples and uterine flushings. Endometrial expression of MAT2B and SMS mRNAs increased in late diestrus (P < 0.05). Expression of ODC1 and SMOX mRNAs decreased from early metestrus to early diestrus, and expression of ASL mRNA was lower in late diestrus than in early metestrus (P < 0.05). Immunoreactive PAOX, SAT1, and SMS proteins were localized to uterine luminal, superficial glandular, and glandular epithelia, stromal cells, myometrium, and blood vessels. Concentrations of spermidine and spermine in maternal plasma decreased from early metestrus to early diestrus and decreased further in late diestrus (P < 0.05). The abundances of spermidine and spermine in uterine flushings were less in late diestrus than early metestrus (P < 0.05). These results indicate that synthesis and secretion of polyamines are affected by P4 and E2, as well as the expression of PGR and ESR1 in the endometria of cyclic ewes.

Dietary supplementation with L-leucine reduces nitric oxide synthesis by endothelial cells of rats

This study tested the hypothesis that elevated L-leucine concentrations in plasma reduce nitric oxide (NO) synthesis by endothelial cells (ECs) and affect adiposity in obese rats. Beginning at four weeks of age, male Sprague-Dawley rats were fed a casein-based low-fat (LF) or high-fat (HF) diet for 15 weeks. Thereafter, rats in the LF and HF groups were assigned randomly into one of two subgroups (n = 8/subgroup) and received drinking water containing either 1.02% L-alanine (isonitrogenous control) or 1.5% L-leucine for 12 weeks. The energy expenditure of the rats was determined at weeks 0, 6, and 11 of the supplementation period. At the end of the study, an oral glucose tolerance test was performed on all the rats immediately before being euthanized for the collection of tissues. HF feeding reduced (P < 0.001) NO synthesis in ECs by 21% and whole-body insulin sensitivity by 19% but increased (P < 0.001) glutamine:fructose-6-phosphate transaminase (GFAT) activity in ECs by 42%. Oral administration of L-leucine decreased (P < 0.05) NO synthesis in ECs by 14%, increased (P < 0.05) GFAT activity in ECs by 35%, and reduced (P < 0.05) whole-body insulin sensitivity by 14% in rats fed the LF diet but had no effect (P > 0.05) on these variables in rats fed the HF diet. L-Leucine supplementation did not affect (P > 0.05) weight gain, tissue masses (including white adipose tissue, brown adipose tissue, and skeletal muscle), or antioxidative capacity (indicated by ratios of glutathione/glutathione disulfide) in LF- or HF-fed rats and did not worsen (P > 0.05) adiposity, whole-body insulin sensitivity, or metabolic profiles in the plasma of obese rats. These results indicate that high concentrations of L-leucine promote glucosamine synthesis and impair NO production by ECs, possibly contributing to an increased risk of cardiovascular disease in diet-induced obese rats.

Synthesis of glycine from 4-hydroxyproline in tissues of neonatal pigs with intrauterine growth restriction

This study tested the hypothesis that the synthesis of glycine from 4-hydroxyproline (an abundant amino acid in milk and neonatal blood) was impaired in tissues of piglets with intrauterine growth restriction (IUGR), thereby contributing to a severe glycine deficiency in these compromised neonates. At 0, 7, 14, and 21 days of age, IUGR piglets were euthanized, and tissues (liver, small intestine, kidney, pancreas, stomach, skeletal muscle, and heart) were obtained for metabolic studies, as well as the determination of enzymatic activities, cell-specific localization, and expression of mRNAs for glycine-synthetic enzymes. The results indicated relatively low enzymatic activities for 4-hydroxyproline oxidase (OH-POX), proline oxidase, serine hydroxymethyltransferase, threonine dehydrogenase (TDH), alanine: glyoxylate transaminase, and 4-hydroxy-2-oxoglutarate aldolase in the kidneys and liver from 0- to 21-day-old IUGR pigs, in the pancreas of 7- to 21-day-old IUGR pigs, and in the small intestine and skeletal muscle (except TDH) of 21-day-old IUGR pigs. Accordingly, the rates of conversion of 4-hydroxyproline into glycine were relatively low in tissues of IUGR piglets. The expression of mRNAs for glycine-synthetic enzymes followed the patterns of enzymatic activities and was also low. Immunohistochemical analyses revealed the relatively low abundance of OH-POX protein in the liver, kidney, and small intestine of IUGR piglets, and the lack of OH-POX zonation in their livers. These novel results provide a metabolic basis to explain why the endogenous synthesis of glycine is insufficient for optimum growth of IUGR piglets and have important implications for improving the nutrition and health of other mammalian neonates including humans with IUGR.

Creatine metabolism at the uterine-placental interface throughout gestation in sheep†

The placenta requires high levels of adenosine triphosphate to maintain a metabolically active state throughout gestation. The creatine-creatine kinase-phosphocreatine system is known to buffer adenosine triphosphate levels; however, the role(s) creatine-creatine kinase-phosphocreatine system plays in uterine and placental metabolism throughout gestation is poorly understood. In this study, Suffolk ewes were ovariohysterectomized on Days 30, 50, 70, 90, 110 and 125 of gestation (n = 3-5 ewes/per day, except n = 2 on Day 50) and uterine and placental tissues subjected to analyses to measure metabolites, mRNAs, and proteins related to the creatine-creatine kinase-phosphocreatine system. Day of gestation affected concentrations and total amounts of guanidinoacetate and creatine in maternal plasma, amniotic fluid and allantoic fluid (P < 0.05). Expression of mRNAs for arginine:glycine amidinotransferase, guanidinoacetate methyltransferase, creatine kinase B, and solute carrier 16A12 in endometria and for arginine:glycine amidinotransferase and creatine kinase B in placentomes changed significantly across days of gestation (P < 0.05). The arginine:glycine amidinotransferase protein was more abundant in uterine luminal epithelium on Days 90 and 125 compared to Days 30 and 50 (P < 0.01). The chorionic epithelium of placentomes expressed guanidinoacetate methyltransferase and solute carrier 6A13 throughout gestation. Creatine transporter (solute carrier 6A8) was expressed by the uterine luminal epithelium and trophectoderm of placentomes throughout gestation. Creatine kinase (creatine kinase B and CKMT1) proteins were localized primarily to the uterine luminal epithelium and to the placental chorionic epithelium of placentomes throughout gestation. Collectively, these results demonstrate cell-specific and temporal regulation of components of the creatine-creatine kinase-phosphocreatine system that likely influence energy homeostasis for fetal-placental development.

Metabolic pathways utilized by the porcine conceptus, uterus, and placenta

Conceptus elongation and early placentation involve growth and remodeling that requires proliferation and migration of cells. This demands conceptuses expend energy before establishment of a placenta connection and when they are dependent upon components of histotroph secreted or transported into the uterine lumen from the uterus. Glucose and fructose, as well as many amino acids (including arginine, aspartate, glutamine, glutamate, glycine, methionine, and serine), increase in the uterine lumen during the peri-implantation period. Glucose and fructose enter cells via their transporters, SLC2A, SLC2A3, and SLC2A8, and amino acids enter the cells via specific transporters that are expressed by the conceptus trophectoderm. However, porcine conceptuses develop rapidly through extensive cellular proliferation and migration as they elongate and attach to the uterine wall resulting in increased metabolic demands. Therefore, coordination of multiple metabolic biosynthetic pathways is an essential aspect of conceptus development. Oxidative metabolism primarily occurs through the tricarboxylic acid (TCA) cycle and the electron transport chain, but proliferating and migrating cells, like the trophectoderm of pigs, enhance aerobic glycolysis. The glycolytic intermediates from glucose can then be shunted into the pentose phosphate pathway and one-carbon metabolism for the de novo synthesis of nucleotides. A result of aerobic glycolysis is limited availability of pyruvate for maintaining the TCA cycle, and trophectoderm cells likely replenish TCA cycle metabolites primarily through glutaminolysis to convert glutamine into TCA cycle intermediates. The synthesis of ATP, nucleotides, amino acids, and fatty acids through these biosynthetic pathways is essential to support elongation, migration, hormone synthesis, implantation, and early placental development of conceptuses.

Synthesis of glycine from 4-hydroxyproline in tissues of neonatal pigs

Glycine from sow's milk only meets 20% of the requirement of suckling piglets. However, how glycine is synthesized endogenously in neonates is not known. This study determined glycine synthesis from 4-hydroxyproline (an abundant amino acid in milk and neonatal blood) in tissues of sow-reared piglets with normal birth weights. Piglets were euthanized at 0, 7, 14 and 21 days of age, and their tissues were used to determine glycine synthesis from 0 to 5 mM 4-hydroxyproline, activities and mRNA expression of key glycine-synthetic enzymes, and their cell-specific localization. Activities of 4-hydroxyproline oxidase (OH-POX), proline oxidase (POX), serine hydroxymethyltransferase (SHMT), threonine dehydrogenase (TDH), alanine:glyoxylate transaminase (AGT), and 4-hydroxy-2-oxoglutarate aldolase (HOA) occurred in the kidneys and liver from all age groups of piglets, and in the pancreas of 7- to 21-day-old piglets. Activities of OH-POX and HOA were absent from the small intestine of newborn pigs but present in the small intestine of 7- to 21-day-old piglets and in the skeletal muscle of 14- to 21-day-old piglets. Between days 0 and 21 of age, the enzymatic activities of OH-POX, AGT, and HOA decreased in the liver and kidneys but increased in the pancreas and small intestine with age. The mRNA levels of these three enzymes changed in a manner similar to their enzymatic activities. In contrast to OH-POX, AGT, and HOA, the enzymatic activities of POX, SHMT, and TDH were present in the kidneys, liver, and intestine of all age groups of piglets. Glycine was synthesized from 0.1 to 5 mM 4-hydroxyproline in the liver and kidney from 0- to 21-day-old piglets, as well as the pancreas, small intestine, and skeletal muscle from 14- to 21-day-old piglets in a concentration-dependent manner. Collectively, our findings indicate that 4-hydroxyproline is used for the synthesis of glycine in tissues of piglets to compensate for the deficiency of glycine in milk.

Nutrition and Gut Health: Recent Advances and Implications for Development of Functional Foods

The small intestine is a highly differentiated and complex organ with many nutritional, physiological, and immunological functions [...].

Impacts of microgravity on amino acid metabolism during spaceflight

Spaceflight exerts an extreme and unique influence on human physiology as astronauts are subjected to long-term or short-term exposure to microgravity. During spaceflight, a multitude of physiological changes, including the loss of skeletal muscle mass, bone resorption, oxidative stress, and impaired blood flow, occur, which can affect astronaut health and the likelihood of mission success. In vivo and in vitro metabolite studies suggest that amino acids are among the most affected nutrients and metabolites by microgravity (a weightless condition due to very weak gravitational forces). Moreover, exposure to microgravity alters gut microbial composition, immune function, musculoskeletal health, and consequently amino acid metabolism. Appropriate knowledge of daily protein consumption, with a focus on specific functional amino acids, may offer insight into potential combative and/or therapeutic effects of amino acid consumption in astronauts and space travelers. This will further aid in the successful development of long-term manned space mission and permanent space habitats.

Towards texture accurate slice interpolation of medical images using PixelMiner

Quantitative image analysis models are used for medical imaging tasks such as registration, classification, object detection, and segmentation. For these models to be capable of making accurate predictions, they need valid and precise information. We propose PixelMiner, a convolution-based deep-learning model for interpolating computed tomography (CT) imaging slices. PixelMiner was designed to produce texture-accurate slice interpolations by trading off pixel accuracy for texture accuracy. PixelMiner was trained on a dataset of 7829 CT scans and validated using an external dataset. We demonstrated the model's effectiveness by using the structural similarity index (SSIM), peak signal to noise ratio (PSNR), and the root mean squared error (RMSE) of extracted texture features. Additionally, we developed and used a new metric, the mean squared mapped feature error (MSMFE). The performance of PixelMiner was compared to four other interpolation methods: (tri-)linear, (tri-)cubic, windowed sinc (WS), and nearest neighbor (NN). PixelMiner produced texture with a significantly lowest average texture error compared to all other methods with a normalized root mean squared error (NRMSE) of 0.11 (p < .01), and the significantly highest reproducibility with a concordance correlation coefficient (CCC) ≥ 0.85 (p < .01). PixelMiner was not only shown to better preserve features but was also validated using an ablation study by removing auto-regression from the model and was shown to improve segmentations on interpolated slices.

Dietary supplementation with L-citrulline improves placental angiogenesis and embryonic survival in gilts

This study was conducted with gilts as an animal model to test the hypothesis that dietary supplementation with L-citrulline (Cit) improves placental angiogenesis and embryonic survival. Between Days 14 and 25 of gestation, each gilt was fed a corn- and soybean-meal-based diet (2 kg/day) supplemented with 0.4% Cit or an isonitrogenous amount of L-alanine (Control). On Day 25 of gestation, gilts were hysterectomized to obtain conceptuses. Amniotic and allantoic fluids and placentae were analyzed for NOx [stable oxidation products of nitric oxide (NO)], polyamines, and amino acids (AAs). Placentae were also analyzed for syntheses of NO and polyamines; concentrations of AAs and related metabolites; and the expression of angiogenic factors and aquaporins (AQPs). Compared to the control group, Cit supplementation increased (P < 0.01) the number of viable fetuses by 2.0 per litter, the number and diameter of placental blood vessels (21% and 24%, respectively), placental weight (15%), and total allantoic and amniotic fluid volumes (20% and 47%, respectively). Cit supplementation also increased (P < 0.01) enzymatic activities of GTP-cyclohydrolase-1 (32%) and ornithine decarboxylase (27%) in placentae; syntheses of NO (29%) and polyamines (26%); concentrations of NOx (19%), tetrahydrobiopterin (28%), polyamines (22%), cAMP (26%), and cGMP (24%) in placentae; total amounts of NOx (22-40%), polyamines (23-40%), AAs (16-255%), glucose (22-44%), and fructose (22-43%) in allantoic and amniotic fluids. Furthermore, Cit supplementation increased (P < 0.05) placental mRNA levels for angiogenic factors (eNOS [84%], GTP-CH1 [55%], PGF [61%], VEGFA120 [26%], and VEGFR2 [137%], as well as AQPs - AQP1 [105%], AQP3 [53%], AQP5 [77%], AQP8 [57%], and AQP9 [31%]). Collectively, dietary Cit supplementation enhanced placental NO and polyamine syntheses as well as angiogenesis to improve conceptus development and survival.

Parametric and Semiparametric Approaches to Analyzing Device-Based Measures of Energy Expenditure in Zucker Diabetic Fatty Rats

BACKGROUND

Obesity results from a chronic imbalance between energy intake and energy expenditure. Total energy expenditure for all physiological functions combined can be measured approximately by calorimeters. These devices assess energy expenditure frequently (e.g., in 60-second epochs), resulting in massive complex data that are nonlinear functions of time. To reduce the prevalence of obesity, researchers often design targeted therapeutic interventions to increase daily energy expenditure.

METHODS

We analyzed previously collected data on the effects of oral interferon tau supplementation on energy expenditure, as assessed with indirect calorimeters, in an animal model for obesity and type 2 diabetes (Zucker diabetic fatty rats). In our statistical analyses, we compared parametric polynomial mixed effects models and more flexible semiparametric models involving spline regression.

RESULTS

We found no effect of interferon tau dose (0 vs. 4 μg/kg body weight/day) on energy expenditure. The B-spline semiparametric model of untransformed energy expenditure with a quadratic term for time performed best in terms of the Akaike information criterion value.

CONCLUSIONS

To analyze the effects of interventions on energy expenditure assessed with devices that collect data at frequent intervals, we recommend first summarizing the high dimensional data into epochs of 30 to 60 minutes to reduce noise. We also recommend flexible modeling approaches to account for the nonlinear patterns in such high dimensional functional data. We provide freely available R codes in GitHub.

Identification of novel characteristic biomarkers and immune infiltration profile for the anaplastic thyroid cancer via machine learning algorithms

PURPOSE

Anaplastic thyroid cancer (ATC) is a rare and lethal malignant cancer. In recent years, the application of molecular-driven targeted therapy and immunotherapy has markedly improved the prognosis of ATC. This study aimed to identify characteristic genes for ATC diagnosis and revealed the role of ATC characteristic genes in drug sensitivity and immune cell infiltration.

METHODS

We downloaded ATC RNA-sequencing data from the GEO database. Following the combination and normalization of the dataset, we first divided the combined datasets into the training cohort and the validation cohort. We identified differentially expressed genes (DEGs) in ATC by differential expression analysis in the training cohort. We used two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) to identify ATC characteristic genes. The CIBERSORT algorithm was performed to calculate the abundance of various immune cells in ATC. Finally, we validated the expression of ATC characteristic genes by quantitative RT-PCR (RT-qPCR) in ATC cell lines and immunohistochemistry (IHC).

RESULTS

A total of 425 DEGs were identified in the training cohort, including 240 upregulated genes and 185 downregulated genes. Four ATC characteristic genes (ADM, PXDN, MMP1, and TFF3) were identified, and their diagnostic value was validated in the validation cohort (AUC in ROC analysis > 0.75). We established a practical gene expression-based nomogram to accurately predict the probability of ATC. We also found that ATC characteristic biomarkers are associated with the tumor immune microenvironment and drug sensitivity.

CONCLUSION

ADM, PXDN, MMP1, and TFF3 might serve as potential ATC diagnostic biomarkers and may be helpful for ATC molecular targeted therapy and immunotherapy.

Dietary glycine supplementation enhances postweaning growth and meat quality of pigs with intrauterine growth restriction

Pigs with intrauterine growth restriction (IUGR) have suboptimum growth performance and impaired synthesis of glycine (the most abundant amino acid in the body). Conventional corn- and soybean meal-based diets for postweaning pigs contain relatively low amounts of glycine and may not provide sufficient glycine to meet requirements for IUGR pigs. This hypothesis was tested using 52 IUGR pigs and 52 litter mates with normal birth weights (NBW). At weaning (21 d of age), IUGR or NBW pigs were assigned randomly to one of two nutritional groups: supplementation of a corn-soybean meal-based diet with either 1% glycine plus 0.19% cornstarch or 1.19% L-alanine (isonitrogenous control). Feed consumption and body weight (BW) of pigs were recorded daily and every 2 or 4 wks, respectively. All pigs had free access to their respective diets and clean drinking water. Within 1 wk after the feeding trial ended at 188 d of age, blood and other tissue samples were obtained from pigs to determine concentrations of amino acids and meat quality. Neither IUGR nor glycine supplementation affected (P > 0.05) feed intakes of pigs per kg BW. The final BW, gain:feed ratio, carcass dressing percentages, and four-lean-cuts percentages of IUGR pigs were 13.4 kg, 4.4%, 2%, and 15% lower (P < 0.05) for IUGR pigs than NBW pigs, respectively. Compared with pigs in the alanine group, dietary glycine supplementation increased (P < 0.05) final BW, gain:feed ratio, and meat a* value (a redness score) by 3.8 kg, 11%, and 10%, respectively, while reducing (P < 0.05) backfat thickness by 18%. IUGR pigs had lower (P < 0.05) concentrations of glycine in plasma (-45%), liver (-25%), jejunum (-19%), longissimus dorsi muscle (-23%), gastrocnemius muscle (-26%), kidney (-15%), and pancreas (-6%), as compared to NBW pigs. In addition, dietary glycine supplementation increased (P < 0.05) concentrations of glycine in plasma and all analyzed tissues. Thus, supplementing 1% of glycine to corn-soybean meal-based diets improves the growth performance, feed efficiency, and meat quality of IUGR pigs.

Dietary glycine supplementation improves the growth performance of 110- to 240-g (phase II) hybrid striped bass (Morone saxatilis ♀× Morone chrysops ♂) fed soybean meal-based diets

We recently reported that supplementing glycine to soybean meal (SBM)-based diets is necessary for optimum growth of 5- to 40-g (phase I) hybrid striped bass (HSB). The present study tested the hypothesis that supplementing glycine to SBM-based diets may enhance the growth of 110- to 240-g (phase II) HSB. HSB (the initial body weight of approximately 110 g) were fed an SBM (58%)-based diet supplemented with 0%, 1%, or 2% of glycine, with l-alanine serving as the isonitrogenous control. There were four tanks per dietary group, with four fish per tank. The fish were fed their respective diets to apparent satiation twice daily. The feed intake and body weight of fish were recorded daily and every 2 wk, respectively. At the end of the 56-d feeding trial, plasma and tissue samples were collected to determine amino acid concentrations and histological alterations, and tissues were used to measure the oxidation of l-glutamate, l-glutamine, l-aspartate, and glycine. Results showed that dietary supplementation with 1% and 2% glycine dose-dependently increased (P < 0.05) the concentration of glycine in the plasma of HSB by 48% and 99%, respectively. Compared with the 0%-glycine group, dietary supplementation with 1% glycine did not affect (P > 0.05) the feed intake of HSB but increased (P < 0.05) their final body weight, weight gain, and gain:feed ratio during the whole period by 13%, 29%, and 21%, respectively. Compared with the 1% glycine group, dietary supplementation with 2% glycine increased (P < 0.05) the feed intake, final body weight, and weight gain of HSB by 13%, 7%, and 14%, respectively. Compared with the 0%-glycine group, fish fed with the 1%-glycine and 2%-glycine diets had a greater (P < 0.05) villus height in the proximal intestine, when compared with the 0%-glycine group. Collectively, these results indicated that SBM-based diets did not provide sufficient glycine for phase II HSB (110 to 240 g) and that dietary glycine supplementation is essential for their optimum growth and intestinal structure.

Dietary glycine supplementation enhances the growth performance of hybrid striped bass (Morone saxatilis ♀× Morone chrysops ♂) fed soybean meal-based diets

This study was conducted to test the hypothesis that supplementing 1% and 2% glycine to soybean meal (SBM)-based diets can improve the growth performance of juvenile hybrid striped bass (HSB). The basal diets contained 15% fishmeal and 58% SBM (DM basis). Alanine was used as the isonitrogenous control in different diets. All diets contained 44% crude protein and 10% lipids (DM basis). There were four tanks (15 fish per tank) per dietary group, with the mean of the initial body weight (BW) of fish being 5.3 g. Fish were fed to apparent satiation twice daily, and their BW was recorded every 2 wk. The trial lasted for 8 wk. Results indicated that the BW, weight gain, protein efficiency ratio, and retention of dietary lipids in fish were enhanced (P < 0.05) by dietary supplementation with 1% or 2% glycine. In addition, dietary supplementation with glycine did not affect (P > 0.05) the feed intake of fish but increased (P < 0.05) the retention of dietary nitrogen, most amino acids, and phosphorus in the body, compared to the 0% glycine group. Dietary supplementation with 1% and 2% glycine dose-dependently augmented (P < 0.05) the villus height of the proximal intestine and reduced the submucosal thickness of the gut, while preventing submucosal and lamina propria hemorrhages. Compared with the 0% glycine group, dietary supplementation with 1% or 2% glycine decreased (P < 0.05) the proportion of skeletal-muscle fibers with diameters of 40 to 60 µm but increased (P < 0.05) the proportion of skeletal-muscle fibers with diameters of 80 to 100 µm and > 100 µm. Collectively, these findings indicate that glycine in SBM-based diets is inadequate for maximum growth of juvenile HSB and that dietary supplementation with 1% or 2% glycine is required to improve their weight gain and feed efficiency. Glycine is a conditionally essential amino acid for this fish.