Women in Metabolism: The Next Generation.

The "Rosies" of Cell Metabolism persist as a new generation enters the stage. With inspiration from this issue's cover art, we celebrate young and diverse scientists and the mentorship that has guided them throughout. Their stories come from different corners of the world but are tied together by a common thread of tenacity and perseverance

Do obesity and physical inactivity underlie the insulin resistance of aging?

Insulin resistance (IR) is the hallmark of type 2 diabetes (T2DM) and can precede its onset for many years. Since the prevalence of T2DM is higher among older adults, it has been suggested that aging is associated with IR. While some studies support the concept of age-related IR, others support the hypothesis that IR may not be associated with aging but rather with lifestyle patterns linked with aging, such as physical inactivity and obesity. To determine the effects of older age on IR independently of physical inactivity and obesity, we compared 7 older and 7 younger normal weight sedentary volunteers matched by gender, body mass index (BMI) and physical inactivity. In normal weight sedentary subjects, i.e., after accounting for both obesity and level of chronic physical activity, aging per se was not associated with IR. To determine the effects of obesity on IR independently of age and physical inactivity, we compared 7 older normal weight sedentary subjects to 14 obese sedentary subjects matched by age, gender and physical inactivity. After accounting for both age and physical inactivity, obesity was associated with both peripheral and hepatic IR. To determine the effects of chronic exercise on IR independently of age and obesity, we compared 14 older endurance trained athletes to 7 normal weight sedentary subjects matched by age and BMI. Within subjects of similar age and body weight, and after adjusting for body fat, higher physical activity was associated with greater peripheral insulin sensitivity, but not with greater hepatic insulin sensitivity. Intramyocellular lipids (IMCL) and fatty acid metabolites such as diacylglycerols (DAG) and ceramides (Cer) may play an important role in the pathophysiology of IR. We demonstrated that intramyocellular triglycerides (IMTG) were higher but ceramide content was lower in athletes. Moreover, the distribution of DAG and ceramide species was different in athletes compared to obese sedentary subjects. In conclusion, these data indicate that IR is not associated with age per se but rather is determined by obesity and physical activity. This study further elucidates the association among intramyocellular lipid content, aging obesity, physical activity and IR

Association between metabolic syndrome, hypertension, and chronic depression: a postmenopausal women prevention study

Background. Chronic depression (CD) is common among postmenopausal women and is associated with an increased risk of cardiovascular disease (CVD). The diagnosis of CD is a challenging problem in clinical practice which is vastly underdiagnosed. CD detection in postmenopausal women with metabolic syndrome (MetS) or hypertension is necessary for CVD prevention. Our study aims to assess the prevalence of CD in postmenopausal women and the relationship between CD and MetS or hypertension. Results. The rate of CD was significantly higher among postmenopausal women with MetS compared with the control group [18% versus 8%; Odds ratio (OR) 2.2, P<0.007]. The CD rate was significantly higher among women with MetS and hypertension (21% versus 8%; OR 2.7, P<0.0000). The rate of CD was similar between women with MetS and women with hypertension, 18% versus 21%; OR 0.8, P<0.44) and between women with metabolic cardiomyopathy and hypertensive cardiomyopathy (10% versus 8%; OR 1.1, P<0.65). Conclusions. There is a relationship between MetS and CD, which is stronger when compared to women with hypertension. There is a need to improve the diagnosis of CD in postmenopausal women with MetS or hypertension as unrecognized and untreated CD is associated with a poor outcome

Lower thigh subcutaneous and higher visceral abdominal adipose tissue content both contribute to insulin resistance.

It is well known that visceral adipose tissue (VAT) is associated with insulin resistance (IR). Considerable debate remains concerning the potential positive effect of thigh subcutaneous adipose tissue (TSAT). Our objective was to observe whether VAT and TSAT are opposite, synergistic or additive for both peripheral and hepatic IR. Fifty-two volunteers (21 male/31 female) between 30 and 75 years old were recruited from the general population. All subjects were sedentary overweight or obese (mean BMI 33.0 ± 3.4 kg/m(2)). Insulin sensitivity was determined by a 4-h hyperinsulinemic-euglycemic clamp with stable isotope tracer dilution. Total body fat and lean body mass were determined by dual X-ray absorptiometry. Abdominal and mid-thigh adiposity was determined by computed tomography. VAT was negatively associated with peripheral insulin sensitivity, while TSAT, in contrast, was positively associated with peripheral insulin sensitivity. Subjects with a combination of low VAT and high TSAT had the highest insulin sensitivity, subjects with a combination of high VAT and low TSAT were the most insulin resistant. These associations remained significant after adjusting for age and gender. These data confirm that visceral excess abdominal adiposity is associated with IR across a range of middle-age to older men and women, and further suggest that higher thigh subcutaneous fat is favorably associated with better insulin sensitivity. This strongly suggests that these two distinct fat distribution phenotypes should both be considered in IR as important determinants of cardiometabolic risk

Vertebral bone marrow fat, bone mineral density and diabetes : The Osteoporotic Fractures in Men (MrOS) study

Elevated vertebral bone marrow fat (BMF) among individuals with osteoporosis has been established in histomorphometric studies. Several studies have found a negative correlation between BMF and bone mineral density (BMD) at the spine in men and women across different age groups. Animal studies have also observed bone loss with increased BMF in mice with induced diabetes. Our study objective was to test the hypothesis that the association between BMF and BMD varies by diabetic status. We performed a cross-sectional study of 156 men aged 74-96years from the Osteoporotic Fractures in Men study at the Pittsburgh clinical site. All men had spine BMF scans using proton magnetic resonance spectroscopy and spine and hip BMD scans by dual-energy X-ray absorptiometry. BMF was expressed as lipid to "lipid+water" ratio (%). Men were considered diabetic if they self-reported a physician diagnosis of diabetes, diabetes medication or had a fasting glucose ≥126mg/dl. Men with diabetes (n=38) had a significantly higher spine BMF (58.9 vs. 54.6%, p=0.0035), spine BMD (1.20 vs. 1.10g/cm(2), P=0.007) and total hip BMD (1.00 vs. 0.94g/cm(2), p=0.04) than those without, while no differences were observed for body weight, body mass index or waist circumference. Pearson correlation tests showed no significant correlation of spine BMF with age or BMD in non-diabetics. Significant inverse correlations were observed between BMF and BMD (-0.30 for femoral neck and -0.39 for total hip) among diabetic men. In conclusion, men with diabetes had a higher BMF compared to non-diabetic men. The correlation between BMF and BMD differed by diabetes status. Further investigation of the association of diabetes with BMF and BMD may provide a better understanding of the high fracture rates among individuals with diabetes despite their higher BMD

Hif1α down-regulation is associated with transposition of great arteries in mice treated with a retinoic acid antagonist

<p>Abstract</p> <p>Background</p> <p>Congenital heart defect (CHD) account for 25% of all human congenital abnormalities. However, very few CHD-causing genes have been identified so far. A promising approach for the identification of essential cardiac regulators whose mutations may be linked to human CHD, is the molecular and genetic analysis of heart development. With the use of a triple retinoic acid competitive antagonist (BMS189453) we previously developed a mouse model of congenital heart defects (81%), thymic abnormalities (98%) and neural tube defects (20%). D-TGA (D-transposition of great arteries) was the most prevalent cardiac defect observed (61%). Recently we were able to partially rescue this abnormal phenotype (CHD were reduced to 64.8%, p = 0.05), by oral administration of folic acid (FA). Now we have performed a microarray analysis in our mouse models to discover genes/transcripts potentially implicated in the pathogenesis of this CHD.</p> <p>Results</p> <p>We analysed mouse embryos (8.5 dpc) treated with BMS189453 alone and with BMS189453 plus folic acid (FA) by microarray and qRT-PCR. By selecting a fold change (FC) ≥ ± 1.5, we detected 447 genes that were differentially expressed in BMS-treated embryos vs. untreated control embryos, while 239 genes were differentially expressed in BMS-treated embryos whose mothers had also received FA supplementation vs. BMS-treated embryos. On the basis of microarray and qRT-PCR results, we further analysed the <it>Hif1α </it>gene. In fact <it>Hif1α </it>is down-regulated in BMS-treated embryos vs. untreated controls (FC_micro= -1.79; FC_qRT-PCR= -1.76; p = 0.005) and its expression level is increased in BMS+FA-treated embryos compared to BMS-treated embryos (FC_micro= +1.17; FC_qRT-PCR= +1.28: p = 0.005). Immunofluorescence experiments confirmed the under-expression of Hif1α protein in BMS-treated embryos compared to untreated and BMS+FA-treated embryos and, moreover, we demonstrated that at 8.5 dpc, Hif1α is mainly expressed in the embryo heart region.</p> <p>Conclusions</p> <p>We propose that Hif1α down-regulation in response to blocking retinoic acid binding may contribute to the development of cardiac defects in mouse newborns. In line with our hypothesis, when Hif1α expression level is restored (by supplementation of folic acid), a decrement of CHD is found. To the best of our knowledge, this is the first report that links retinoic acid metabolism to Hif1α regulation and the development of D-TGA.</p

In Vitro Acute Exposure to DEHP Affects Oocyte Meiotic Maturation, Energy and Oxidative Stress Parameters in a Large Animal Model

Phthalates are ubiquitous environmental contaminants because of their use in plastics and other common consumer products. Di-(2-ethylhexyl) phthalate (DEHP) is the most abundant phthalate and it impairs fertility by acting as an endocrine disruptor. The aim of the present study was to analyze the effects of in vitro acute exposure to DEHP on oocyte maturation, energy and oxidative status in the horse, a large animal model. Cumulus cell (CC) apoptosis and oxidative status were also investigated. Cumulus-oocyte complexes from the ovaries of slaughtered mares were cultured in vitro in presence of 0.12, 12 and 1200 µM DEHP. After in vitro maturation (IVM), CCs were removed and evaluated for apoptosis (cytological assessment and TUNEL) and intracellular reactive oxygen species (ROS) levels. Oocytes were evaluated for nuclear chromatin configuration. Matured (Metaphase II stage; MII) oocytes were further evaluated for cytoplasmic energy and oxidative parameters. DEHP significantly inhibited oocyte maturation when added at low doses (0.12 µM; P<0.05). This effect was related to increased CC apoptosis (P<0.001) and reduced ROS levels (P<0.0001). At higher doses (12 and 1200 µM), DEHP induced apoptosis (P<0.0001) and ROS increase (P<0.0001) in CCs without affecting oocyte maturation. In DEHP-exposed MII oocytes, mitochondrial distribution patterns, apparent energy status (MitoTracker fluorescence intensity), intracellular ROS localization and levels, mt/ROS colocalization and total SOD activity did not vary, whereas increased ATP content (P<0.05), possibly of glycolytic origin, was found. Co-treatment with N-Acetyl-Cysteine reversed apoptosis and efficiently scavenged excessive ROS in DEHP-treated CCs without enhancing oocyte maturation. In conclusion, acute in vitro exposure to DEHP inhibits equine oocyte maturation without altering ooplasmic energy and oxidative stress parameters in matured oocytes which retain the potential to be fertilized and develop into embryos even though further studies are necessary to confirm this possibility

Mutational analysis of Peroxiredoxin IV: exclusion of a positional candidate for multinodular goitre

BACKGROUND: Multinodular goitre (MNG) is a common disorder characterised by an enlargement of the thyroid, occurring as a compensatory response to hormonogenesis impairment. The incidence of MNG is dependent on sex (female:male ratio 5:1) and several reports have documented a genetic basis for the disease. Last year we mapped a MNG locus to chromosome Xp22 in a region containing the peroxiredoxin IV (Prx-IV) gene. Since Prx-IV is involved in the removal of H(2)O(2) in thyroid cells, we hypothesize that mutations in Prx-IV gene are involved in pathogenesis of MNG. METHODS: Four individuals (2 affected, 2 unrelated unaffected) were sequenced using automated methods. All individuals were originated from the original three-generation Italian family described in previous studies. A Southern blot analysis using a Prx-IV full-length cDNA as a probe was performed in order to exclude genomic rearrangements and/or intronic mutations. In addition a RT-PCR of PRX-IV was performed in order to investigate expression alterations. RESULTS: No causative mutations were found. Two adjacent nucleotide substitutions were detected within introns 1 and 4. These changes were also detected in unaffected individuals, suggesting that they were innocuous polymorphisms. No gross genomic rearrangements and/or restriction fragment alterations were observed on Southern analysis. Finally, using RT-PCR from tissue-specific RNA, no differences of PRX-IV expression-levels were detected between affected and unaffected samples. CONCLUSIONS: Based on sequence and genomic analysis, Prx-IV is very unlikely to be the MNG2 gene