A U-shaped protection of altitude against mortality and infection of COVID-19 in Peru: an ecological study.

BACKGROUND: The COVID-19 pandemic has affected the world in multiple ways and has been a challenge for the health systems of each country. From the beginning, risk factors for the severity and mortality of the disease were considered, as the spread of the virus was related to the living conditions of each population. METHODS: In this ecological study we have evaluated the role of geography, precisely the altitude above sea level in the incidence and mortality of COVID-19 in Peru. Incidence and mortality data were taken from the open-access database of the government of Peru until March 2021. COVID-19 cases and COVID-19 mortality were treated as cases/density population and 1000 x cases/inhabitants while altitude was treated as continuous and as a categorical variable divided in 7 categories. The relationship between COVID-19 cases or deaths for COVID-19 and altitude as continuous variable was determined using Spearman correlation test. Meanwhile when altitude was considered as a categorical variable, Poisson regression or negative binomial analyses were applied. RESULTS: A significant inverse correlation was found between COVID-19 cases by population density and altitude (r=-0.37 p < 0.001). By altitude categories, the lowest risk for infection was observed between 3,000 and 3,500 m (IRR 0.08; 95% CI 0.05,0.12). Moreover, we found an inverse correlation between altitude and COVID-19 mortality (r=-0.39 p < 0.001). Also, the lowest risk for mortality was observed between 3,000 and 3,500 m (IRR 0.12; 95%CI 0.08; 0.18). Similar results were found when analyses were adjusted for inhabitants and stratified by sex. CONCLUSION: This study reports an inverse relationship between COVID-19 incidence and mortality with respect to the altitude of residence, particularly, a u-shaped protection is shown, with a highest benefit between 3000 and 3500 m. The possibility of using hypoxia as an alternative treatment requires more complex studies that should allow knowing the physiological and environmental mechanisms of the protective role.

Perinatal maternal feeding with an energy dense diet and/or micronutrient mixture drives offspring fat distribution depending on the sex and growth stage.

Maternal nutrition during pregnancy and lactation influences offspring development and health. Novel studies have described the effects on next generation obesity-related features depending on maternal macro- and micro-nutrient perinatal feeding. We hypothesized that the maternal obesogenic diet during pregnancy and lactation programs an obese phenotype, while maternal micronutrient supplementation at these stages could partially prevent these features. Thus, the aim was to assess the influence of a perinatal maternal feeding with an obesogenic diet enriched in fat and sucrose and a micronutrient supplementation during pregnancy and lactation on offspring growth and obese phenotypical features during life course. Female Wistar rats were assigned to four dietary groups during pregnancy and lactation: control, control supplemented with micronutrients (choline, betaine, folic acid and vitamin B12 ), high-fat sucrose (HFS) and HFS supplemented. At weaning, the offspring were transferred to a chow diet, and weight and fat mass were measured at weeks 3, 12 and 20. At birth, both male and female offspring from mothers fed the obesogenic diet showed lower body weight (-5 and -6%, respectively), while only female offspring weight decreased by maternal micronutrient supplementation (-5%). During lactation, maternal HFS diet was associated with increased body weight, while micronutrient supplementation protected against body weight gain. Whole body fat mass content increased at weeks 3, 12 and 20 (from 16 to 65%) due to maternal HFS diet. Maternal micronutrient supplementation decreased offspring fat mass content at week 3 (-8%). Male offspring showed higher adiposity than females at weeks 12 and 20. In conclusion, maternal HFS feeding during pregnancy and lactation was associated with a low offspring weight at birth and obese phenotypical features during adult life in a sex- and time-dependent manner. Furthermore, maternal methyl donor supplementation protected against body weight gain in male offspring during lactation and in female offspring also during juvenile period.

Expression of endogenous retroviruses is negatively regulated by the pluripotency marker Rex1/Zfp42.

Rex1/Zfp42 is a Yy1-related zinc-finger protein whose expression is frequently used to identify pluripotent stem cells. We show that depletion of Rex1 levels notably affected self-renewal of mouse embryonic stem (ES) cells in clonal assays, in the absence of evident differences in expression of marker genes for pluripotency or differentiation. By contrast, marked differences in expression of several endogenous retroviral elements (ERVs) were evident upon Rex1 depletion. We demonstrate association of REX1 to specific elements in chromatin-immunoprecipitation assays, most strongly to muERV-L and to a lower extent to IAP and musD elements. Rex1 regulates muERV-L expression in vivo, as we show altered levels upon transient gain-and-loss of Rex1 function in pre-implantation embryos. We also find REX1 can associate with the lysine-demethylase LSD1/KDM1A, suggesting they act in concert. Similar to REX1 binding to retrotransposable elements (REs) in ES cells, we also detected binding of the REX1 related proteins YY1 and YY2 to REs, although the binding preferences of the two proteins were slightly different. Altogether, we show that Rex1 regulates ERV expression in mouse ES cells and during pre-implantation development and suggest that Rex1 and its relatives have evolved as regulators of endogenous retroviral transcription.

Influence of different oxygen supply on metabolic markers and gene response in murine adipocytes.

Obese subjects often present a low-grade chronic inflammation in the white adipose tissue, which seems to play an important role in the initiation and development of obesity-related diseases. It has been reported that this inflammatory process may be due to a hypoxic state occuring within this tissue. Oxygen is used in current medicine as a treatment for several conditions. The aim of this study is to analyze the effects of 95 percent O2 on specific metabolic variables and on the expression of some genes on murine adipocytes. 3T3-L1 adipocytes were exposed during 48 h to different treatments: 95 percent O2 hyperoxia (HPx group), CoCl2 (CoCl2 group), hyperoxia with CoCl2 (HPx+CoCl2 group) and 1 percent O2 hypoxia (Hx group). Cell viability, intracellular ROS content, glucose utilization, lactate and glycerol concentrations were measured. Also, mRNA expression of HIF-1alpha, GLUT-1, ANGPTL4, PPAR-gamma, adiponectin, IL-6 and MCP-1 genes was analyzed. Importantly, 95 percent O2 decreased cell viability and increased intracellular ROS production. Also, glycerol and lactate release were significantly increased and decreased, respectively, in HPx treated cells. This treatment also provoked a down-regulation of GLUT-1 and ANGPTL-4, while IL-6 and MCP-1 were up-regulated. Exposure to a hyperoxia of 95 percent O2 provoked an inflammatory response in adipocytes. The two hypoxia-inducing conditions (CoCl2 and 1 percent O2) produced different outcomes in metabolic measurements as well as in the expression of some genes (GLUT-1, ANPGTL4, PPAR-gamma and adiponectin), while it remained similar in others (HIF-1alpha, IL-6 and MCP-1). Indeed, hyperoxia increased significantly the ROS levels and the lipolytic activity, while it reduced lactate production. In addition to the effects on inflammation, the changes in GLUT-1, ANGPTL4 and PPAR-gamma genes lead to suppose that hyperoxia may be beneficial for the hypertrophied adipose tissues of obese subjects and for improving insulin sensitivity.

Maresin 1 regulates insulin signaling in human adipocytes as well as in adipose tissue and muscle of lean and obese mice.

Maresin 1 (MaR1) is a DHA-derived pro-resolving lipid mediator. The present study aimed to characterize the ability of MaR1 to prevent the alterations induced by TNF-α on insulin actions in glucose uptake and Akt phosphorylation in cultured human adipocytes from overweight/obese subjects, as well as to investigate the effects of MaR1 acute and chronic administration on Akt phosphorylation in absence/presence of insulin in white adipose tissue (WAT) and skeletal muscle from lean and diet-induced obese (DIO) mice. MaR1 (0.1 nM) prevented the inhibitory effect of TNF-α on insulin-stimulated 2-Deoxy-D-glucose uptake and Akt phosphorylation in human adipocytes. Acute treatment with MaR1 (50 µg/kg, 3 h, i.p.) induced Akt phosphorylation in WAT and skeletal muscle of lean mice. However, MaR1 did not further increase the stimulatory effect of insulin on Akt activation. Interestingly, intragastric chronic treatment with MaR1 (50 µg/kg, 10 days) in DIO mice reduced the hyperglycemia induced by the high fat diet (HFD) and improved systemic insulin sensitivity. In parallel, MaR1 partially restored the impaired insulin response in skeletal muscle of DIO mice and reversed HFD-induced lower Akt phosphorylation in WAT in non-insulin-stimulated DIO mice while did not restore the defective Akt activation in response to acute insulin observed in DIO mice. Our results suggest that MaR1 attenuates the impaired insulin signaling and glucose uptake induced by proinflammatory cytokines. Moreover, the current data support that MaR1 treatment could be useful to reduce the hyperglycemia and the insulin resistance associated to obesity, at least in part by improving Akt signaling.

Prevention of systemic lupus erythematosus in autoimmune BXSB mice by a transgene encoding I-E alpha chain.

Males from the BXSB murine strain (H-2b) spontaneously develop an autoimmune syndrome with features of systemic lupus erythematosus (SLE), which results in part from the action of a mutant gene (Yaa) located on the Y chromosome. Like other H-2b mice, the BXSB strain does not express the class II major histocompatibility complex antigen, I-E. Here we report that the expression of I-E (E alpha dE beta b) in BXSB males bearing an E alpha d transgene prevents hypergammaglobulinemia, autoantibody production, and subsequent autoimmune glomerulonephritis. These transgenic mice bear on the majority of their B cells not only I-E molecules, but also an I-E alpha chain-derived peptide presented by a higher number of I-Ab molecules, as recognized by the Y-Ae monoclonal antibody. The I-E+ B cells appear less activated in vivo than the I-E- B cells, a minor population. This limited activation of the I-E+ B cells does not reflect a functional deficiency of this cell population, since it can be stimulated to IgM production in vitro by lipopolysaccharides at an even higher level than the I-E- B cell population. The development of the autoimmune syndrome in the transgenic and nontransgenic bone marrow chimeric mice argues against the possibility that the induction of regulatory T cells or clonal deletion of potential autoreactive T cells as a result of I-E expression is a mechanism of the protection conferred by the E alpha d transgene. We propose a novel mechanism by which the E alpha d transgene protects BXSB mice against SLE: overexpression of I-E alpha chains results in the generation of excessive amounts of a peptide displaying a high affinity to the I-Ab molecule, thereby competing with pathogenic autoantigen-derived peptides for presentation by B lymphocytes and preventing their excessive stimulation.

Expression of a tumor necrosis factor alpha transgene in murine pancreatic beta cells results in severe and permanent insulitis without evolution towards diabetes.

Mice bearing a tumor necrosis factor (TNF) alpha transgene controlled by an insulin promoter developed an increasingly severe lymphocytic insulitis, apparently resulting from the induction of endothelial changes with features similar to those observed in other places of intense lymphocytic traffic. This was accompanied by dissociation of the endocrine tissue (without marked decrease in its total mass), islet fibrosis, and the development of intraislet ductules containing, by places, beta cells in their walls, suggesting a regenerative capacity. Islet disorganization and fibrosis did not result from lymphocytic infiltration, since they were also observed in SCID mice bearing the transgene. Diabetes never developed, even though a number of potentially inducing conditions were used, including the prolonged perfusion of interferon gamma and the permanent expression of a nontolerogenic viral protein on beta cells (obtained by using mice bearing two transgenes). It is concluded that (a) a slow process of TNF release in pancreatic islets induces insulitis, and may be instrumental in the insulitis resulting from local cell-mediated immune reactions, but (b) that insulitis per se is not diabetogenic, lymphocyte stimulation by cells other than beta cells being necessary to trigger extensive beta cell damage. This provides an explanation for the discrepancy between the occurrence of insulitis and that of clinical disease in autoimmune diabetes.

Upregulation of the expression of inflammatory and angiogenic markers in human adipocytes by a synthetic cannabinoid, JTE-907.

Inflammation in adipose tissue is a characteristic of obesity and the metabolic syndrome. It is suggested that the endocannabinoid system is involved in the regulation of inflammatory and angiogenic processes within the tissue. Human subcutaneous preadipocytes (Zen Bio) were used as the source of human preadipocytes or adipocytes. Gene expression was examined by RT-PCR and real-time PCR. The secretion of inflammation-related proteins was determined by an ELISA array. In experiments on adipocytes treated at day 14 post-differentiation, JTE-907, a synthetic cannabinoid, upregulated the expression of key inflammatory markers - IL-6, MCP-1 and IL-1 beta - and angiogenic factors - VEGF and ANGPTL4 - at 10 microM after 20 h of treatment, having also increased the expression of TRPV1 at 10 microM. JTE-907 showed no effect after 4 h. The ELISA array showed a 2.6-fold increase in IL-6 protein release. The effect of JTE-907 was inhibited by AM251 (CB1 antagonist), and partially by arachidonyl serotonin (TRPV1 and FAAH antagonist). The CB2 antagonist, AM630, partially upregulated the effect of JTE-907. Preadipocytes fed 14 days after 100% confluence exhibited downregulation of CB1, MCP-1, and IL-1 beta, 20 h after having been exposed to JTE-907. CB1 and TRPV1 receptors participate in the regulation of several inflammatory and angiogenic factors in human adipocytes, indicating their potential value as targets for the treatment of disorders related to obesity.

Maresin 1 Regulates Hepatic FGF21 in Diet-Induced Obese Mice and in Cultured Hepatocytes.

SCOPE: To study the effects of Maresin 1 (MaR1), a docosahexaenoic-acid-derived lipid mediator, on fibroblast growth factor 21 (FGF21) production and to characterize the tissue-specific regulation of Fgf21 and its signaling pathway in liver, skeletal muscle, and white adipose tissue (WAT). METHODS AND RESULTS: Diet-induced obese (DIO) mice are treated with MaR1 (50 µg kg-1 , 10 days, oral gavage) and serum FGF21 levels and liver, muscle and WAT Fgf21, ß-Klotho, Fgfr1, Egr1, and cFos mRNA expression are evaluated. Additionally, MaR1 effects are tested in mouse primary hepatocytes, HepG2 human hepatocytes, C2C12 myotubes, and 3T3-L1 adipocytes. In DIO mice, MaR1 decreases circulating FGF21 levels and HFD-induced hepatic Fgf21 mRNA expression. MaR1 increases hepatic ß-Klotho, Egr1, and cFos in DIO mice. In WAT, MaR1 counteracts the HFD-induced downregulation of Fgf21, Fgfr1, and ß-Klotho. In muscle, MaR1 does not modify Fgf21 but promoted Fgfr1 expression. In mouse primary hepatocytes, MaR1 decreases Fgf21 expression and downregulated Pparα mRNA levels. In HepG2 cells, MaR1 reverses the increased production of FGF21 and the downregulation of FGFR1, Β-KLOTHO, EGR1, and cFOS induced by palmitate. Preincubation with a PPARα antagonist prevents MaR1 effects on FGF21 secretion. CONCLUSION: The ability of MaR1 to modulate FGF21 can contribute to its beneficial metabolic effects.

Energy restriction in obese subjects impact differently two mitochondrial function markers.

Excessive fat deposition is the key feature in obesity, which is empowered by cytokines overproduction and stimulation of cell oxidative stress processes, but little is known about energy availability in the form of ATP and mitochondrial function in the obese subjects. Thus, the aim of this study was to evaluate the possible changes in energy metabolism after a 8-weeks balanced-hypocaloric diet in obese subjects by measuring the ATP-content in leukocytes, by assessing 2-keto[1-13C]isocaproate breath test (KICA-BT) parameters related to mitochondrial function and by analyzing inflammatory and oxidative stress biomarkers. All the recruited obese subjects (n = 19) lost body weight after dieting (-5.55 +/- 2.88%). The hypocaloric treatment induced a decrease in leptin levels and lipid peroxidation markers. Interestingly, the ATP content in blood leukocytes increased (49.9 +/- 32.5 vs 36.2 +/- 27.9 pmol/mg prot.; p < 0.05), while KICA tracer mitochondrial oxidation decreased (30.9 +/- 5.9 vs. 33.1 +/- 4.5 % 13C; p < 0.05) after weight loss. These results show that two minimally invasive methods were able to detect changes in mitochondrial function as induced by a hypocaloric diet, which is of great interest in order to understand oxidative processes associated with weight homeostasis as well as to establish newer anti-obesity therapeutic targets by using mitochondrial function markers in vivo.

Targeted gene disruption reveals a leptin-independent role for the mouse beta3-adrenoceptor in the regulation of body composition.

Targeted disruption of mouse beta3-adrenoceptor was generated by homologous recombination, and validated by an acute in vivo study showing a complete lack of effect of the beta3-adrenoceptor agonist CL 316,243 on the metabolic rate of homozygous null (-/-) mice. In brown adipose tissue, beta3-adrenoceptor disruption induced a 66% decrease (P < 0.005) in beta1-adrenoceptor mRNA level, whereas leptin mRNA remained unchanged. Chronic energy balance studies in chow-fed mice showed that in -/- mice, body fat accumulation was favored (+41%, P < 0.01), with a slight increase in food intake (+6%, NS). These effects were accentuated by high fat feeding: -/- mice showed increased total body fat (+56%, P < 0.025) and food intake (+12%, P < 0.01), and a decrease in the fat-free dry mass (-10%, P < 0.05), which reflects a reduction in body protein content. Circulating leptin levels were not different in -/- and control mice regardless of diet. The significant shift to the right in the positive correlation between circulating leptin and percentage of body fat in high fat-fed -/- mice suggests that the threshold of body fat content inducing leptin secretion is higher in -/- than in control mice. Taken together, these studies demonstrate that beta3-adrenoceptor disruption creates conditions which predispose to the development of obesity.

Ectopic UCP1 gene expression in HepG2 cells affects ATP production.

The UCP1 is an uncoupling protein located in the inner mitochondrial membrane of brown adipocytes, which has a well-documented role in diet-induced thermogenesis. The current study assessed whether UCP1 transfected liver cells demand more fuel substrates in the oxidative phosphorylation processes. Therefore, the purpose of this experiment was to achieve an ectopic expression of UCP1 in HepG2 cells to significantly decrease the production of ATP. The UCP1 gene was transferred into the hepatic cells by using a calcium phosphate precipitation protocol. The efficiency of the transfection was tested, 48 hours later, by bioluminescence of luciferase previously transfected, while the expression of mRNA of UCP1 was demonstrated by RT-PCR. In addition, measuring the production of ATP by using a bioluminescence procedure assessed the functionality of this protein. Transfected liver cells with UCP1 showed a decrease of 23% in ATP production in comparison with control cells without expression of UCP1 (2.23 vs. 2.90 RLU/pg protein, p=0.015). In conclusion, the ectopic expression of UCP1 decreased the production of ATP, possibly uncoupling the oxidative phosphorylation, which could be a novel approach for understanding thermogenic processes and eventually for energy metabolism and body weight management.

Impact of intermittent hypoxia and exercise on blood pressure and metabolic features from obese subjects suffering sleep apnea-hypopnea syndrome.

Strategies designed to reduce adiposity and cardiovascular-accompanying manifestations have been based on nutritional interventions conjointly with physical activity programs. The aim of this 13-week study was to investigate the putative benefits associated to hypoxia plus exercise on weight loss and relevant metabolic and cardiorespiratory variables, when prescribed to obese subjects with sleep apnea syndrome following dietary advice. The participants were randomly distributed in the following three groups: control, normoxia, and hypoxia. All the subjects received dietary advice while, additionally, normoxia group was trained under normal oxygen concentration and Hypoxia group under hypoxic conditions. There was a statistically significant decrease in fat-free mass (Kg) and water (%) on the control compared to normoxia group (p < 0.05 and p < 0.01, respectively). Body weight, body mass index, and waist circumference decreased in all the groups after the study. Moreover, leukocyte count was increased after the intervention in hypoxia compared to control group (p < 0.05). There were no statistically significant variations within groups in other variables, although changes in appetite were found after the 13-week period. In addition, associations between the variations in the leukocyte count and fat mass have been found. The hypoxia group showed some specific benefits concerning appetite and cardiometabolic-related measurements as exertion time and diastolic blood pressure, with a therapeutical potential.

Expression of the genes for alpha-type and beta-type calcitonin gene-related peptide during postnatal rat brain development.

In this study we have analysed the expression of the genes for both alpha-type and beta-type calcitonin gene-related peptide (CGRP) during postnatal development of the rat brain and compared it with the expression of CGRP-like immunoreactivity. At birth both alpha-type and beta-type CGRP messenger RNA were present in the parabrachial nucleus, inferior olive and motor nuclei (except for abducens nucleus), and only alpha-type CGRP messenger RNA in some posterior thalamic nuclei. As development advanced, new nuclei started to express either only alpha-CGRP gene (superior olive, parabigeminal, sagulum, and some hypothalamic and cranial thalamic nuclei) or both genes (abducens nucleus). In the inferior olive both genes were transiently expressed. Beta-CGRP messenger RNA disappeared by postnatal day 10 and alpha-CGRP messenger RNA by postnatal day 20. During the whole postnatal development beta-CGRP gene expression predominated over that of alpha-CGRP in the trigeminal and eye motor nuclei, while in the remainder nuclei alpha-CGRP messenger RNA was either the predominant isoform or the sole one. CGRP-like immunoreactivity, which does not distinguish between alpha-type and beta-type CGRP, was detected in those nuclei containing either alpha-CGRP messenger RNA or beta-CGRP messenger RNA. However, no CGRP messenger RNA was detected in areas such as superior colliculus, lateral pontine nucleus, pars reticulata of the substantia nigra, perifornical area, or zona incerta in which CGRP-like immunoreactivity was prominent. CGRP-like immunoreactivity, but not CGRP messenger RNA, was also transiently detected by postnatal day 5 in some cells of the globus pallidus. In the adult brain, the levels of alpha- and beta-CGRP messenger RNA as well as those of CGRP-like immunoreactivity were considerably reduced. This fact, similar to that of other growth- and development-associated factors, suggests a role for CGRP as a neuron-derived neurotrophic factor. The transient expression in neurons of the inferior olive, matching the period when climbing fibres and cerebellar cortex are developing, seems to support such an idea. The results of this study show that those nuclei expressing beta-CGRP gene also express alpha-CGRP gene. However, there are a number of nuclei that only express alpha-CGRP gene. On the other hand, CGRP-like immunoreactivity is detected in some nuclei which express no CGRP messenger RNA. It suggests that such nuclei express any CGRP-related protein (identified by the antibodies against CGRP) or, if they really contain CGRP protein, this is produced from undetectable amounts (using our in situ hybridization histochemistry procedure) of CGRP messenger RNA or it comes from other nuclei that connect with them in which CGRP protein is synthesized and then transferred.

Differential expression of alpha-CGRP and beta-CGRP genes within hypoglossal motoneurons in response to axotomy.

In this study we have analysed, by in situ hybridization, the expression of the genes for both alpha-CGRP and beta-CGRP in hypoglossal motor nuclei following transection of the left hypoglossal nerve. Our results show that the gene for alpha-CGRP displays a peculiar sequence of regulation (a successive up-down-up-recovery sequence) within ipsilateral hypoglossal motoneurons in response to axotomy. It is initially up-regulated, then down-regulated (displaying mRNA levels below basal), and later again up-regulated before recovery. By contrast, the gene for beta-CGRP displays a successive and distinct up-down-recovery sequence of regulation (it does not display a second increase in mRNA production). The first up-regulation of the alpha-CGRP gene occurs just during the early period of perineuronal glial reaction and the second up-regulation just during the period of delayed astrocyte reaction and muscle reinnervation. Because alpha-CGRP is a neuron-derived factor for many types of cells, including astrocytes and skeletal myocytes, our results suggest that the pleiotropic alpha-CGRP may be a motoneuron-derived trophic signal for both glial and skeletal muscle cells in order to maintain the motoneuron itself and, in consequence, might be of therapeutic interest in treating degenerative disease of motoneurons. beta-CGRP might be redundant within the hypoglossal motoneurons.

Effects of hyperoxia exposure on metabolic markers and gene expression in 3T3-L1 adipocytes.

Adipose tissue often becomes poorly oxygenated in obese subjects. This feature may provide cellular mechanisms involving chronic inflammation processes such as the release of pro-inflammatory cytokines and macrophage infiltration. In this context, the purpose of the present study was to determine whether a hyperoxia exposure on mature adipocytes may influence the expression of some adipokines and involve favorable changes in specific metabolic variables. Thus, 3T3-L1 adipocytes (14 days differentiated) were treated with 95 % oxygen for 24 h. Cell viability, intra and extracellular reactive oxygen species (ROS) content, glucose uptake, as well as lactate and glycerol concentrations were measured in the culture media. Also, mRNA levels of hypoxia-inducible factor (HIF)-1α, leptin, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, peroxisome proliferator-activated receptor (PPAR)-γ, adiponectin, and angiopoietin-related protein (ANGPTL)4 were analyzed. Hyperoxia treatment increased intra and extracellular ROS content, reduced glucose uptake and lactate release and increased glycerol release. Additionally, a higher oxygen tension led to an upregulation of the expression of IL-6, MCP-1, and PPAR-γ, while ANGPTL4 was downregulated in the hyperoxia group with respect to control. The present data shows that hyperoxia treatment seems to produce an inflammatory response due to the release of ROS and the upregulation of pro-inflammatory adipokines, such as IL-6 and MCP-1. On the other hand, hyperoxia may have an indirect effect on insulin sensitivity due to the upregulation of PPAR-γ signaling as well as a possible modulation of both glucose and lipid metabolic markers. To our knowledge, this is the first study analyzing the effect of hyperoxia in 3T3-L1 adipocytes.

Association of Rex-1 to target genes supports its interaction with Polycomb function.

Rex-1/Zfp42 displays a remarkably restricted pattern of expression in preimplantation embryos, primary spermatocytes, and undifferentiated mouse embryonic stem (ES) cells and is frequently used as a marker gene for pluripotent stem cells. To understand the role of Rex-1 in selfrenewal and pluripotency, we used Rex-1 association as a measure to identify potential target genes, and carried out chromatin-immunoprecipitation assays in combination with gene specific primers to identify genomic targets Rex-1 associates with. We find association of Rex-1 to several genes described previously as bivalently marked regulators of differentiation and development, whose repression in mouse embryonic stem (ES) cells is Polycomb Group-mediated, and controlled directly by Ring1A/B. To substantiate the hypothesis that Rex-1 contributes to gene regulation by PcG, we demonstrate interactions of Rex-1 and YY2 (a close relative of YY1) with Ring1 proteins and the PcG-associated proteins RYBP and YAF2, in line with interactions reported previously for YY1. We also demonstrate the presence of Rex-1 protein in both trophectoderm and Inner Cell Mass of the mouse blastocyst and in both ES and in trophectoderm stem (TS) cells. In TS cells, we were unable to demonstrate association of Rex-1 to the genes it associates with in ES cells, suggesting that association may be cell-type specific. Rex-1 might fine-tune pluripotency in ES cells by modulating Polycomb-mediated gene regulation.

Regulation by chronic-mild stress of glucocorticoids, monocyte chemoattractant protein-1 and adiposity in rats fed on a high-fat diet.

Stress has been reported as a widespread problem and several studies have linked obesity and inflammation-related diseases. Moreover, the combination of suffering from chronic stress and high energy intake might be related to the onset of some metabolic diseases. To study the possible relationships between stress, inflammatory status and obesity, a chronic-mild stress (CMS) paradigm with a high-fat dietary intake model (Cafeteria diet) was implemented on male Wistar rats for 11 weeks. Stress and dietary intake effects on animal adiposity, serum biochemical as well as glucocorticoids and inflammation markers were all analyzed. As expected, consuming a high-fat diet increased body weight, adiposity and insulin resistance in non-stressed animals. A decrease of total white adipose tissue (WAT) and an increase of fecal glucocorticoids, as well as angiotensinogen, and monocyte chemoattractant protein-1 (MCP-1) expression level in retroperitoneal WAT were found only on control-stressed rats. Regarding the serum MCP-1, a decrease was observed on animals under CMS while being fed Cafeteria diet. Furthermore, 11ß-hydroxysteroid dehydrogenase activity, a glucocorticoid and obesity biomarker in the liver, was influenced by high-fat diet intake but not by stress. Finally, statistical analysis showed a strong relation between MCP-1 expression levels in retroperitoneal WAT, fecal corticosterone and total WAT. This trial proved that CMS induced a glucocorticoid-mediated response, which was reduced by the intake of a Cafeteria diet. These findings suggest that a high-fat diet could protect against a stress condition and revealed a different behavior to a stressful environment depending on the nutritional status.

A morphological study of primordial germ cells at pregastrular stages in the chick embryo.

The spatial distribution, germ layer location, number and appearance of primordial germ cells (PGCs) are studied. Blastoderms from stage X (Eyal-Giladi and Kochav, 1976) to stage 2 (Hamburger and Hamilton, 1951) were serially sectioned and distribution patterns of PGCs were reconstructed. The presence of PGCs in clusters was noted at all stages examined. PGCs were found in relation to the epiblast, the primary hypoblast and in the blastocoel, during the whole period under examination. These observations show that PGCs can be directly studied at blastula stages. The results are consistent with observations on an early segregation of chick germ line that begins as early as stage X.