Metabolic actions of insulin in men and women

Sex differences in adipose insulin resistance are linked to obesity, lipolysis and insulin receptor substrate 1

BACKGROUND/OBJECTIVE

Insulin resistance is more prominent in men than women. If this involves adipose tissue is unknown and was presently examined.

SUBJECTS/METHODS

AdipoIR (in vivo adipose insulin resistance index) was measured in 2344 women and 787 men. In 259 of the women and 54 of the men, insulin induced inhibition of lipolysis (acylglycerol breakdown) and stimulation of lipogenesis (glucose conversion to acylglycerols) were determined in subcutaneous adipocytes; in addition, basal (spontaneous) lipolysis was also determined in the fat cells. In 234 women and 115 men, RNAseq expression of canonical insulin signal genes were measured in subcutaneous adipose tissue. Messenger RNA transcripts of the most discriminant genes were quantified in 175 women and 109 men.

RESULTS

Men had higher AdipoIR values than women but only when obesity (body mass index 30 kg/m2 or more) was present (p < 0.0001). The latter sex dimorphism was found among physically active and sedentary people, in those with and without cardiometabolic disease and in people using nicotine or not (p = 0.0003 or less). In obesity, adipocyte insulin sensitivity (half maximum effective hormone concentration) and maximal antilipolytic effect were tenfold and 10% lower, respectively, in men than women (p = 0.005 or less). Basal rate of lipolysis was two times higher in men than women (p > 0.0001). Sensitivity and maximum effect of insulin on lipogenesis were similar in both sexes (p = 0.26 and p = 0.18, respectively). When corrected for multiple comparison only RNAseq expression of insulin receptor substrate 1 (IRS1) was lower in men than women (p < 0.0001). The mRNA transcript for IRS1 was 60% higher in women than men (p < 0.0001).

CONCLUSIONS

In obesity, adipose tissue insulin resistance is more pronounced in men than in women. The mechanism involves less efficient insulin-mediated inhibition of adipocyte lipolysis, increased basal rate of lipolysis and decreased adipose expression of a key element of insulin signaling, IRS1.

Chronic and immediate refined carbohydrate consumption and facial attractiveness

The Western diet has undergone a massive switch since the second half of the 20th century, with the massive increase of the consumption of refined carbohydrate associated with many adverse health effects. The physiological mechanisms linked to this consumption, such as hyperglycaemia and hyperinsulinemia, may impact non medical traits such as facial attractiveness. To explore this issue, the relationship between facial attractiveness and immediate and chronic refined carbohydrate consumption estimated by glycemic load was studied for 104 French subjects. Facial attractiveness was assessed by opposite sex raters using pictures taken two hours after a controlled breakfast. Chronic consumption was assessed considering three high glycemic risk meals: breakfast, afternoon snacking and between-meal snacking. Immediate consumption of a high glycemic breakfast decreased facial attractiveness for men and women while controlling for several control variables, including energy intake. Chronic refined carbohydrate consumption had different effects on attractiveness depending on the meal and/or the sex. Chronic refined carbohydrate consumption, estimated by the glycemic load, during the three studied meals reduced attractiveness, while a high energy intake increased it. Nevertheless, the effect was reversed for men concerning the afternoon snack, for which a high energy intake reduced attractiveness and a high glycemic load increased it. These effects were maintained when potential confounders for facial attractiveness were controlled such as age, age departure from actual age, masculinity/femininity (perceived and measured), BMI, physical activity, parental home ownership, smoking, couple status, hormonal contraceptive use (for women), and facial hairiness (for men). Results were possibly mediated by an increase in age appearance for women and a decrease in perceived masculinity for men. The physiological differences between the three meals studied and the interpretation of the results from an adaptive/maladaptive point of view in relation to our new dietary environment are discussed.

The effect of dairy products on liver fat and metabolic risk markers in males with abdominal obesity - a four-arm randomized controlled trial

BACKGROUND & AIMS

In recent years, epidemiological studies have reported links between the consumption of fermented dairy products, such as yogurt, and health; however, evidence from human intervention trials is scarce and inconsistent. We aimed to investigate the effect of consumption of four different types of dairy products (two fermented and two non-fermented) on liver fat (primary outcome) and metabolic risk markers in males with abdominal obesity.

METHODS

In this parallel randomized controlled trial with four arms, 100 males aged 30-70 years, with body mass index 28.0-45.0 kg/m2, and waist circumference ≥102 cm underwent a 16-weeks intervention where they were instructed to consume 400 g/day of either milk, yogurt, heat-treated yogurt, or acidified milk as part of their habitual diet. Liver fat was measured by magnetic resonance imaging.

RESULTS

In the complete case analyses (n = 80), no effects of the intervention or differences between groups were detected in anthropometry or body composition including liver fat. Moreover, no effects were detected in inflammatory markers. Main effects of time were detected in blood pressure (decrease; P < 0.001), insulin (decrease; P < 0.001), C-peptide (decrease; P = 0.040), homeostatic model assessment for insulin resistance (decrease; P < 0.001), total cholesterol (decrease; P = 0.016), low-density lipoprotein (decrease; P = 0.033), high-density lipoprotein (decrease; P = 0.006), and alanine transaminase (decrease; P = 0.019). Interactions between group and time failed to reach significance.

CONCLUSIONS

In conclusion, findings from our study do not confirm that fermented yogurt products are superior in reducing liver fat or improving metabolic risk markers compared to non-fermented milk products. In fact, all intervention products (both fermented yogurt products and non-fermented milk products) did not affect liver fat and caused largely similar modest favorable changes in some metabolic risk markers. The study was registered at www.

CLINICALTRIALS

gov (# NCT04755530).

Urinary C-peptide and total triiodothyronine as energetic biomarkers for studies of lemurs

Measuring energy balance and energy metabolism can provide crucial information for understanding the ecological and behavioral drivers of an animal's energetic and physiological condition. Both urinary C-peptide (uCP) of insulin and urinary total triiodothyronine (uTT3) have been validated as noninvasive biomarkers of energy balance and metabolic activity in haplorrhine primates. This study attempts to validate uCP and uTT3 measures in strepsirrhines, a phylogenetically distinct primate clade, using the ruffed lemur (genus Varecia) as a model. We experimentally manipulated the diet of captive black-and-white (Varecia variegata) and red (Varecia rubra) ruffed lemurs at Duke Lemur Center across a 4-week period. We collected urine samples from subjects (n = 5) each day during 1 week of control diet, 2 weeks of calorie-restricted diet and 1 week of refeeding, designed to temporarily reduce energy balance and metabolism. We also tested the outcome of filter paper as a storage method by comparing to controls (frozen at -20°C) to assess its suitability for studies of wild populations. We successfully measured uCP and uTT3 levels in frozen urine samples using commercial enzyme immunoassay kits and found that both biomarkers were excreted at lower concentrations (C-peptide: 1.35 ng/mL, 54% reduction; TT3: 1.5 ng/mL, 37.5% reduction) during calorie-restricted periods compared to normal diet periods. Filter paper recovery for uCP was 19%, though values were significantly positively correlated with frozen control samples. uTT3 could not be recovered at measurable concentrations using filter paper. These methods enable noninvasive measurement of energetic conditions in wild strepsirrhines and subsequent assessment of relationships between energy balance and numerous socioecological drivers in primate populations.

Insulin signaling promotes neurogenesis in the brain of adult zebrafish

Insulin is a peptide hormone that plays a central role in the regulation of circulating blood glucose in vertebrates, including zebrafish. Increasing evidence has demonstrated the important role of insulin in many brain functions. In zebrafish, two insulin receptor genes (insra and insrb) have been identified. However, their biodistribution in the adult brain as well as their cell-specific expression pattern has not been well described. Using gene expression analysis, in situ hybridization and transgenic fish, we confirmed the expression of insra, insrb, and irs1 (insulin receptor substrate 1, the downstream effector of insulin receptor) in the brain of adult zebrafish and characterized their specific expression in neurons and neural stem cells (radial glia). After demonstrating that intracerebroventricular (ICV) injection resulted in the diffusion of the injected solution within the ventricular system, we analyzed the effect of insulin ICV injection on neurogenesis. We showed that insulin promotes ventricular cell proliferation 24 h postinjection. This neurogenic effect appeared to be independent of neuroinflammatory processes. Also, after a mechanical telencephalic stab-wound injury, we highlighted the overexpression of irs1 gene 5 days postlesion notably in the ventricular zone where radial glial cells (RGCs) are localized, suggesting key roles of insulin signaling in regenerative processes. Finally, our results reinforced the expression of insulin-related proteins in the brain of adult zebrafish, highlighting the potential role of insulin signaling on neurogenesis.

Serum metabolomics profiling by proton nuclear magnetic resonance spectrometry of the response to single oral macronutrient challenges in women with polycystic ovary syndrome (PCOS) compared with male and female controls

BACKGROUND

The polycystic ovary syndrome (PCOS) is associated with insulin resistance, obesity and cardiometabolic comorbidities. We here challenged the hypothesis, using state-of-the-art proton nuclear magnetic resonance spectrometry (1H-NMRS) metabolomics profiling, that androgen excess in women induces a certain masculinization of postprandial metabolism that is modulated by obesity.

MATERIALS AND METHODS

Participants were 53 Caucasian young adults, including 17 women with classic PCOS consisting of hyperandrogenism and ovulatory dysfunction, 17 non-hyperandrogenic women presenting with regular menses, and 19 healthy men, selected to be similar in terms of age and body mass index (BMI). Half of the subjects had obesity. Patients were submitted to isocaloric separate glucose, lipid and protein oral challenges in alternate days and fasting and postprandial serum samples were submitted to 1H-NMRS metabolomics profiling for quantification of 36 low-molecular-weight polar metabolites.

RESULTS

The largest postprandial changes were observed after glucose and protein intake, with lipid ingestion inducing smaller differences. Changes after glucose intake consisted of a marked increase in carbohydrates and byproducts of glycolysis, and an overall decrease in byproducts of proteolysis, lipolysis and ketogenesis. After the protein load, most amino acids and derivatives increased markedly, in parallel to an increase in pyruvate and a decrease in 3-hydroxybutyric acid and glycerol. Obesity increased β- and D-glucose and pyruvate levels, with this effect being observed mostly after glucose ingestion in women with PCOS. Regardless of the type of macronutrient, men presented increased lysine and decreased 3-hydroxybutyric acid. In addition, non-obese men showed increased postprandial β-glucose and decreased pyroglutamic acid, compared with non-obese control women. We observed a common pattern of postprandial changes in branched-chain and aromatic amino acids, where men showed greater amino acids increases after protein intake than control women and patients with PCOS but only within the non-obese participants. Conversely, this increase was blunted in obese men but not in obese women, who even presented a larger increase in some amino acids compared with their non-obese counterparts. Interestingly, regardless of the type of macronutrient, only obese women with PCOS showed increased leucine, lysine, phenylalanine and tryptophan levels compared with non-obese patients.

CONCLUSIONS

Serum 1H-NMRS metabolomics profiling indicated sexual dimorphism in the responses to oral macronutrient challenges, which were apparently driven by the central role of postprandial insulin effects with obesity, and to a lesser extent PCOS, exerting modifying roles derived from insulin resistance. Hence, obesity impaired metabolic flexibility in young adults, yet sex and sex hormones also influenced the regulation of postprandial metabolism.

Asian females without diabetes are protected from obesity-related dysregulation of glucose metabolism compared with males

OBJECTIVE

The impact of obesity on the risk for type 2 diabetes differs between males and females; however, the underlying reasons are unclear. This study aimed to investigate the effect of sex on obesity-driven changes in the mechanisms regulating glucose metabolism (insulin sensitivity and secretion) among Asian individuals without diabetes in Singapore.

METHODS

The study assessed glucose tolerance using oral glucose tolerance test, insulin-mediated glucose uptake using hyperinsulinemic-euglycemic clamp, acute insulin response using an intravenous glucose challenge, and insulin secretion rates in the fasting state and in response to glucose ingestion using mathematical modeling in 727 males and 952 females who had normal body weight (n = 602, BMI < 23 kg/m2 ), overweight (n = 662, 23 ≤ BMI < 27.5), or obesity (n = 415, BMI ≥ 27.5).

RESULTS

There were no sex differences among lean individuals. Obesity gradually worsened metabolic function, and the progressive adverse effects of obesity on insulin action and secretion were more pronounced in males than females, such that among participants with obesity, females had greater insulin sensitivity, lower insulin secretion, and lower fasting insulin concentration than males. The increase in waist to hip ratio with increasing BMI was more pronounced in males than females.

CONCLUSIONS

The female sex exerts a protective effect on obesity-driven dysregulation of glucose metabolism in Asian individuals without diabetes.

Molecular Mechanisms for the Vicious Cycle between Insulin Resistance and the Inflammatory Response in Obesity

The comprehensive anabolic effects of insulin throughout the body, in addition to the control of glycemia, include ensuring lipid homeostasis and anti-inflammatory modulation, especially in adipose tissue (AT). The prevalence of obesity, defined as a body mass index (BMI) ≥ 30 kg/m², has been increasing worldwide on a pandemic scale with accompanying syndemic health problems, including glucose intolerance, insulin resistance (IR), and diabetes. Impaired tissue sensitivity to insulin or IR paradoxically leads to diseases with an inflammatory component despite hyperinsulinemia. Therefore, an excess of visceral AT in obesity initiates chronic low-grade inflammatory conditions that interfere with insulin signaling via insulin receptors (INSRs). Moreover, in response to IR, hyperglycemia itself stimulates a primarily defensive inflammatory response associated with the subsequent release of numerous inflammatory cytokines and a real threat of organ function deterioration. In this review, all components of this vicious cycle are characterized with particular emphasis on the interplay between insulin signaling and both the innate and adaptive immune responses related to obesity. Increased visceral AT accumulation in obesity should be considered the main environmental factor responsible for the disruption in the epigenetic regulatory mechanisms in the immune system, resulting in autoimmunity and inflammation.

The roles of dietary lipids and lipidomics in gut-brain axis in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM), one of the main types of Noncommunicable diseases (NCDs), is a systemic inflammatory disease characterized by dysfunctional pancreatic β-cells and/or peripheral insulin resistance, resulting in impaired glucose and lipid metabolism. Genetic, metabolic, multiple lifestyle, and sociodemographic factors are known as related to high T2DM risk. Dietary lipids and lipid metabolism are significant metabolic modulators in T2DM and T2DM-related complications. Besides, accumulated evidence suggests that altered gut microbiota which plays an important role in the metabolic health of the host contributes significantly to T2DM involving impaired or improved glucose and lipid metabolism. At this point, dietary lipids may affect host physiology and health via interaction with the gut microbiota. Besides, increasing evidence in the literature suggests that lipidomics as novel parameters detected with holistic analytical techniques have important roles in the pathogenesis and progression of T2DM, through various mechanisms of action including gut-brain axis modulation. A better understanding of the roles of some nutrients and lipidomics in T2DM through gut microbiota interactions will help develop new strategies for the prevention and treatment of T2DM. However, this issue has not yet been entirely discussed in the literature. The present review provides up-to-date knowledge on the roles of dietary lipids and lipidomics in gut-brain axis in T2DM and some nutritional strategies in T2DM considering lipids- lipidomics and gut microbiota interactions are given.

Bidirectional Mendelian randomization study of insulin-related traits and risk of ovarian cancer

BACKGROUND

It is well known that the occurrence and development of ovarian cancer are closely related to the patient's weight and various endocrine factors in the body.

AIM

Mendelian randomization (MR) was used to analyze the bidirectional relationship between insulin related characteristics and ovarian cancer.

METHODS

The data on insulin related characteristics are from up to 5567 diabetes free patients from 10 studies, mainly including fasting insulin level, insulin secretion rate, peak insulin response, etc. For ovarian cancer, UK Biobank data just updated in 2021 was selected, of which the relevant gene data was from 199741 Europeans. Mendelian randomization method was selected, with inverse variance weighting (IVW) as the main estimation, while MR Pleiotropy, MR Egger, weighted median and other methods were used to detect the heterogeneity of data and whether there was multi validity affecting conclusions.

RESULTS

Among all insulin related indicators (fasting insulin level, insulin secretion rate, peak insulin response), the insulin secretion rate was selected to have a causal relationship with the occurrence of ovarian cancer (IVW, P < 0.05), that is, the risk of ovarian cancer increased with the decrease of insulin secretion rate. At the same time, we tested the heterogeneity and polymorphism of this indicator, and the results were non-existent, which ensured the accuracy of the analysis results. Reverse causal analysis showed that there was no causal effect between the two (P>0.05).

CONCLUSION

The impairment of the insulin secretion rate has a causal effect on the risk of ovarian cancer, which was confirmed by Mendel randomization. This suggests that the human glucose metabolism cycle represented by insulin secretion plays an important role in the pathogenesis of ovarian cancer, which provides a new idea for preventing the release of ovarian cancer.

The Role of Insulin Resistance in Fueling NAFLD Pathogenesis: From Molecular Mechanisms to Clinical Implications

Non-alcoholic fatty liver disease (NAFLD) represents a predominant hepatopathy that is rapidly becoming the most common cause of hepatocellular carcinoma worldwide. The close association with metabolic syndrome’s extrahepatic components has suggested the nature of the systemic metabolic-related disorder based on the interplay between genetic, nutritional, and environmental factors, creating a complex network of yet-unclarified pathogenetic mechanisms in which the role of insulin resistance (IR) could be crucial. This review detailed the clinical and pathogenetic evidence involved in the NAFLD–IR relationship, presenting both the classic and more innovative models. In particular, we focused on the reciprocal effects of IR, oxidative stress, and systemic inflammation on insulin-sensitivity disruption in critical regions such as the hepatic and the adipose tissue, while considering the impact of genetics/epigenetics on the regulation of IR mechanisms as well as nutrients on specific insulin-related gene expression (nutrigenetics and nutrigenomics). In addition, we discussed the emerging capability of the gut microbiota to interfere with physiological signaling of the hormonal pathways responsible for maintaining metabolic homeostasis and by inducing an abnormal activation of the immune system. The translation of these novel findings into clinical practice could promote the expansion of accurate diagnostic/prognostic stratification tools and tailored pharmacological approaches.

Insulin and cancer: a tangled web

For a century, since the pioneering work of Otto Warburg, the interwoven relationship between metabolism and cancer has been appreciated. More recently, with obesity rates rising in the U.S. and worldwide, epidemiologic evidence has supported a link between obesity and cancer. A substantial body of work seeks to mechanistically unpack the association between obesity, altered metabolism, and cancer. Without question, these relationships are multifactorial and cannot be distilled to a single obesity- and metabolism-altering hormone, substrate, or factor. However, it is important to understand the hormone-specific associations between metabolism and cancer. Here, we review the links between obesity, metabolic dysregulation, insulin, and cancer, with an emphasis on current investigational metabolic adjuncts to standard-of-care cancer treatment.

Continuous Glucose Monitoring in Healthy Adults—Possible Applications in Health Care, Wellness, and Sports

Introduction: Continuous glucose monitoring (CGM) systems were primarily developed for patients with diabetes mellitus. However, these systems are increasingly being used by individuals who do not have diabetes mellitus. This mini review describes possible applications of CGM systems in healthy adults in health care, wellness, and sports. Results: CGM systems can be used for early detection of abnormal glucose regulation. Learning from CGM data how the intake of foods with different glycemic loads and physical activity affect glucose responses can be helpful in improving nutritional and/or physical activity behavior. Furthermore, states of stress that affect glucose dynamics could be made visible. Physical performance and/or regeneration can be improved as CGM systems can provide information on glucose values and dynamics that may help optimize nutritional strategies pre-, during, and post-exercise. Conclusions: CGM has a high potential for health benefits and self-optimization. More scientific studies are needed to improve the interpretation of CGM data. The interaction with other wearables and combined data collection and analysis in one single device would contribute to developing more precise recommendations for users.

Obesity, Body Composition, and Sex Hormones: Implications for Cardiovascular Risk

Cardiovascular disease (CVD) continues to be the leading cause of death in adults, highlighting the need to develop novel strategies to mitigate cardiovascular risk. The advancing obesity epidemic is now threatening the gains in CVD risk reduction brought about by contemporary pharmaceutical and surgical interventions. There are sex differences in the development and outcomes of CVD; premenopausal women have significantly lower CVD risk than men of the same age, but women lose this advantage as they transition to menopause, an observation suggesting potential role of sex hormones in determining CVD risk. Clear differences in obesity and regional fat distribution among men and women also exist. While men have relatively high fat in the abdominal area, women tend to distribute a larger proportion of their fat in the lower body. Considering that regional body fat distribution is an important CVD risk factor, differences in how men and women store their body fat may partly contribute to sex-based alterations in CVD risk as well. This article presents findings related to the role of obesity and sex hormones in determining CVD risk. Evidence for the role of sex hormones in determining body composition in men and women is also presented. Lastly, the clinical potential for using sex hormones to alter body composition and reduce CVD risk is outlined. © 2022 American Physiological Society. Compr Physiol 12:1-45, 2022.

Insects as a New Complex Model in Hormonal Basis of Obesity

Nowadays, one of the biggest problems in healthcare is an obesity epidemic. Consumption of cheap and low-quality energy-rich diets, low physical activity, and sedentary work favor an increase in the number of obesity cases within many populations/nations. This is a burden on society, public health, and the economy with many deleterious consequences. Thus, studies concerning this disorder are extremely needed, including searching for new, effective, and fitting models. Obesity may be related, among other factors, to disrupting adipocytes activity, disturbance of metabolic homeostasis, dysregulation of hormonal balance, cardiovascular problems, or disorders in nutrition which may lead to death. Because of the high complexity of obesity, it is not easy to find an ideal model for its studies which will be suitable for genetic and physiological analysis including specification of different compounds’ (hormones, neuropeptides) functions, as well as for signaling pathways analysis. In recent times, in search of new models for human diseases there has been more and more attention paid to insects, especially in neuro-endocrine regulation. It seems that this group of animals might also be a new model for human obesity. There are many arguments that insects are a good, multidirectional, and complex model for this disease. For example, insect models can have similar conservative signaling pathways (e.g., JAK-STAT signaling pathway), the presence of similar hormonal axis (e.g., brain–gut axis), or occurrence of structural and functional homologues between neuropeptides (e.g., neuropeptide F and human neuropeptide Y, insulin-like peptides, and human insulin) compared to humans. Here we give a hint to use insects as a model for obesity that can be used in multiple ways: as a source of genetic and peptidomic data about etiology and development correlated with obesity occurrence as well as a model for novel hormonal-based drug activity and their impact on mechanism of disease occurrence.

Beyond the X Factor: Relevance of Sex Hormones in NAFLD Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) is a major health issue worldwide, being frequently associated with obesity, unbalanced dietary regimens, and reduced physical activity. Despite their greater adiposity and reduced physical activity, women show a lower risk of developing NAFLD in comparison to men, likely a consequence of a sex-specific regulation of liver metabolism. In the liver, sex differences in the uptake, synthesis, oxidation, deposition, and mobilization of lipids, as well as in the regulation of inflammation, are associated with differences in NAFLD prevalence and progression between men and women. Given the major role of sex hormones in driving hepatic sexual dimorphism, this review will focus on the role of sex hormones and their signaling in the regulation of hepatic metabolism and in the molecular mechanisms triggering NAFLD development and progression.

Echocardiographic parameters according to insulin dose in young patients affected by type 1 diabetes

Insulin dose has been found to associate to several cardiometabolic risk factors in type 1 diabetes. Changes over time in body weight and composition may partly explain this association. However, no data are available on the relationship between insulin dose and echocardiographic parameters of both systolic and diastolic function in type 1 diabetes. Therefore, the aim of the present study was to examine systolic and diastolic echocardiographic parameters in relation to insulin dose in young patients with type 1 diabetes. The study was carried out on 93 consecutive outpatients with type 1 diabetes with a mean age of 32.8 ± 9.8 years. All patients were examined with a transthoracic echocardiography. Clinical and laboratory data were collected. The median value of daily insulin dose was used to categorized patients in two groups: high and low insulin dose group. Patients belonging to the high insulin dose group showed higher levels of cardiometabolic risk factors such as BMI, triglycerides and TG/HDL cholesterol ratio. Indexes of both systolic and diastolic function were similar in both groups except isovolumetric relaxation time (IVRT), that was significantly prolonged in patients of the high insulin group (94.4 ± 15.0 vs 86.7 ± 13.1 ms, p = 0.008). In the multivariate regression analysis, insulin dose was positively and significantly associated with IVRT. In this study we report an association between insulin dose and impaired active diastolic myocardial relaxation. Future studies are needed to further explore this observation.

Relationship between Lipoprotein (a) and cognitive function - Results from the Berlin Aging Study II

It has been suggested that an age-related loss of cognitive function might be driven by atherosclerotic effects associated with altered lipid patterns. However, the relationship between Lipoprotein (a) [Lp(a)] and healthy cognitive aging has not yet been sufficiently investigated. For the current analysis we used the cross-sectional data of 1,380 Berlin Aging Study II (BASE-II) participants aged 60 years and older (52.2% women, mean age 68 ± 4 years). We employed the Consortium to Establish a Registry for Alzheimer's Disease (CERAD)-Plus test battery to establish latent factors representing continuous measures of domain specific cognitive functions. Regression models adjusted for APOE genotypes, lipid parameters and other risk factors for cognitive impairment were applied to assess the association between Lp(a) and performance in specific cognitive domains. Men within the lowest Lp(a)-quintile showed better cognitive performance in the cognitive domain executive functions and processing speed (p = 0.027). No significant results were observed in women. The results of the current analysis of predominantly healthy BASE-II participants point towards an association between low Lp(a) concentrations and better cognitive performance. However, evidence for this relationship resulting from the current analysis and the employment of a differentiated cognitive assessment is rather weak.

Lactation Ketoacidosis: A Systematic Review of Case Reports

Background and Objective: Lactation ketoacidosis is a rare cause of high anion gap metabolic acidosis affecting breastfeeding mothers. We aim to review and analyze all cases of lactation ketoacidosis reported. Materials and Methods: A systematic search of PubMed/MEDLINE and Cumulative Index to Nursing and Allied Health Literature (CINAHL), identifying relevant case reports published from 1 January 1970 to 31 December 2019. We extracted the following data: the first author, country, year of publication, age of the mother, age of the child, weight/body mass index (BMI) of the mother, precipitating factors, presenting symptoms, biochemical results, treatment, breastfeeding, and time from presentation to the resolution of ketoacidosis. Results: Sixteen case reports and 1 case series reporting 18 cases of lactation ketoacidosis were found. Presenting symptoms were nausea (72%, 13/18), vomiting (67%, 12/18), malaise (56%, 10/18), abdominal pain (44%, 8/18), dyspnea (33%, 6/18), headache (22%, 4/18), and palpitation (11%, 2/18). Dieting and physical exercise to lose weight were reported in 76% (14/18). The treatments included IV dextrose, sodium bicarbonate, insulin, rehydration, monitoring and replacement of electrolytes, and resumption of a balanced diet. The prognoses were good, with no mortalities. Conclusions: lactation ketoacidosis should be suspected in unwell breastfeeding women with high anion gap metabolic acidosis, after excluding other causes.

Acute exercise effects on postprandial fat oxidation: meta-analysis and systematic review

The purpose of this systematic review was to synthesize and evaluate current literature examining the effects of exercise on postprandial fat oxidation, as well as to provide future direction. A quantitative review was performed using meta-analytic methods. A moderator analysis was performed to investigate potential variables that could influence the effect of exercise on postprandial fat oxidation. Fifty-six effects from 26 studies were retrieved. There was a moderate effect of exercise on postprandial fat oxidation (Cohen's d = 0.58 (95% CI, 0.39 to 0.78)). Moderator analysis revealed that sex, age, weight status, training status, exercise type, exercise intensity, timing of exercise, and composition of the meal challenge significantly affected the impact of prior exercise on postprandial fat oxidation. The moderator analysis also indicated that most previous studies have investigated the impact of prior moderate-intensity endurance exercise on postprandial fat oxidation in young, healthy, lean men. Suggested priorities for future research in this area include (i) an examination of sex differences in and/or female-specific aspects of postprandial metabolism; (ii) a comprehensive evaluation of exercise modalities, intensities, and durations; and (iii) a wider variety of test meal compositions, especially those with higher fat content. Novelty A systematic review of the impact of exercise on postprandial fat oxidation was performed using meta-analytic methods. Analysis revealed a moderate effect of exercise on postprandial fat oxidation. The presented data support a need for future studies to investigate sex differences and to include comprehensive evaluations of exercise modalities, intensities, and duration.

Obesity and Body Composition in Man and Woman: Associated Diseases and the New Role of Gut Microbiota

BACKGROUND

Obesity is now recognized as a worldwide health issue and has reached epidemic proportions, affecting both developed and developing countries. The World Obesity Federation stated that "Obesity is a chronic relapsing disease process": as a result, obesity has been recognized internationally as a chronic disease. The primary cause of the metabolic syndrome and increase of the cardiovascular risk have been identified in "sick fat", a condition then defined as adiposopathy. Heart attacks, strokes and renal failures are pathologies that have mid-risk factors such as dyslipidemia, hypertension and diabetes, which in turn are caused by obesity, whose primary risk factor is represented by the diet. The aim of the present review is to consider the importance of body composition, together with chronic inflammation and a new gut microbiota data that may turn out to be crucial elements of some target treatment of human obesity.

METHODS

In this review, we performed research using PubMed database reviewing the evidence in the literature of evidence information regarding the link between obesity and body composition in the development of metabolic disease via inflammation markers and in particular, the new role exerted by gut microbiota.

RESULTS

Several papers were evaluated searching for differences in fat mass and disease risk. We also identified the same papers dealing with differences in body composition and metabolic syndrome. Our attention focuses also on a new frontier of gut microbiota composition in the body weight decrease and anti-inflammatory effects.

CONCLUSION

To the saving of lean mass, for the prevention of cardiometabolic diseases, also considering the relationship with obesity, it is necessary to reduce the inflammatory state, acting on the gut-microbiota and on the intestinal permeability. To improve the health of the intestinal flora, we propose a 4P medicine and treatment with probiotics, prebiotics, postbiotics, and polyphenols.

International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing

Background

In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~ 60% of energy intake, 5–8 g·kg^− 1·d^− 1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~ 1.6 g·kg^− 1·d^− 1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g.kg^− 1·d^− 1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150–400 Kcal·h^− 1 (carbohydrate, 30–50 g·h^− 1; protein, 5–10 g·h^− 1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450–750 mL·h^− 1 (~ 150–250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., > 575 mg·L^− 1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety.

Sex Dependent Dysregulation of Hepatic Glucose Production in Lean Type 2 Diabetic Rats

We have characterized a lean type 2 diabetic rat model by gestational low protein programming. We aimed to identify if the regulation of hepatic glucose production (HGP) via gluconeogenesis and glycogenolysis is affected and if there are any sex differences. Fasting (6-7 months old) type 2 diabetic rats received 2H2O followed by a primed constant rate infusion of [6,6-2H2] glucose. Blood samples were drawn during steady states after 4 h of fasting and following a euglycemic hyperinsulinemic clamp. HGP and the fraction of glucose derived from gluconeogenesis under fasting and euglycemic states were measured from steady state glucose enrichments after the infusion of [6,6-2H2]glucose and 2H2O tracers. Glycogenolysis was determined by calculating the difference between total HGP and gluconeogenesis rates. Hepatic gene expression of enzymes involved in HGP were quantified using qPCR. HGP rates was similar during fasting in both groups and sexes. However, under simulated fed condition, HGP rate was suppressed in controls but not in type 2 diabetic rats. They also showed inefficient HGP suppression in a simulated fed state. Differential analysis showed that suppression of both gluconeogenesis and glycogenolysis under simulated fed state was affected in these low protein programmed type 2 diabetic rats. These effects were greater in females when compared to males. Further, key genes involved in these processes like G6Pase, Pepck, pyruvate carboxylase, and glycogen phosphorylase in liver were dysregulated. Our data shows impaired suppression of HGP via gluconeogenesis and glycogenolysis in type 2 diabetic rats with greater effects on females.

Family-based quantitative trait meta-analysis implicates rare noncoding variants in DENND1A in polycystic ovary syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is among the most common endocrine disorders of premenopausal women, affecting 5-15% of this population depending on the diagnostic criteria applied. It is characterized by hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology. PCOS is highly heritable, but only a small proportion of this heritability can be accounted for by the common genetic susceptibility variants identified to date.

OBJECTIVE

The objective of this study was to test whether rare genetic variants contribute to PCOS pathogenesis.Design, Patients, and Methods: We performed whole-genome sequencing on DNA from 261 individuals from 62 families with one or more daughters with PCOS. We tested for associations of rare variants with PCOS and its concomitant hormonal traits using a quantitative trait meta-analysis.

RESULTS

We found rare variants in DENND1A (P=5.31×10-5, Padj=0.039) that were significantly associated with reproductive and metabolic traits in PCOS families.

CONCLUSIONS

Common variants in DENND1A have previously been associated with PCOS diagnosis in genome-wide association studies. Subsequent studies indicated that DENND1A is an important regulator of human ovarian androgen biosynthesis. Our findings provide additional evidence that DENND1A plays a central role in PCOS and suggest that rare noncoding variants contribute to disease pathogenesis.

Association of Insulin Dose, Cardiometabolic Risk Factors, and Cardiovascular Disease in Type 1 Diabetes During 30 Years of Follow-up in the DCCT/EDIC Study

OBJECTIVE

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study demonstrated the beneficial effects of intensive therapy on atherosclerosis and clinical cardiovascular disease (CVD) outcomes. The current analyses evaluated the relationship between longitudinal changes in insulin dose and CVD risk factors and outcomes.

RESEARCH DESIGN AND METHODS

A total of 1,441 participants were randomly assigned to intensive or conventional diabetes therapy during the DCCT. After an average of 6.5 years of follow-up, 96% of the surviving cohort enrolled in the EDIC observational study, which included annual visits with detailed medical history, physical examination, and laboratory testing. CVD events were adjudicated by a review committee. Generalized linear mixed models and Cox proportional hazards regression models were used to assess the association between insulin dose and cardiometabolic risk factors and CVD risk, respectively, over a total of 30 years.

RESULTS

Higher insulin doses were significantly associated with a less favorable cardiometabolic risk profile (higher BMI, pulse rate, and triglycerides and lower HDL cholesterol) with the exception of lower diastolic blood pressure and lower LDL cholesterol. In a minimally adjusted model, a 0.1 unit/kg body wt/day increase in insulin dose was associated with a 6% increased risk of any CVD (95% CI 3, 9). However, the association with insulin dose was no longer significant after adjustment for other CVD risk factors.

CONCLUSIONS

During DCCT/EDIC, higher insulin doses were associated with adverse trends in several cardiometabolic risk factors, even after multivariable adjustment, but not with incident CVD outcomes.

Impaired Skeletal Muscle Branched-Chain Amino Acids Catabolism Contributes to Their Increased Circulating Levels in a Non-Obese Insulin-Resistant Fructose-Fed Rat Model

Elevated plasma branched-chain amino acids (BCAA) levels are often observed in obese insulin-resistant (IR) subjects and laboratory animals. A reduced capacity of the adipose tissues (AT) to catabolize BCAA has been proposed as an explanation, but it seems restricted to obesity models of genetically modified or high fat⁻fed rodents. We aimed to determine if plasma BCAA levels were increased in a model of IR without obesity and to explore the underlying mechanisms. Rats were fed with a standard diet, containing either starch or fructose. BCAA levels, body weight and composition were recorded before and after 5, 12, 30, or 45 days of feeding. Elevated blood BCAA levels were observed in our IR model with unaltered body weight and composition. No changes were observed in the liver or the AT, but instead an impaired capacity of the skeletal muscle to catabolize BCAA was observed, including reduced capacity for transamination and oxidative deamination. Although the elevated blood BCAA levels in the fructose-fed rat seem to be a common feature of the IR phenotype observed in obese subjects and high fat⁻fed animals, the mechanisms involved in such a metabolic phenomenon are different, likely involving the skeletal muscle BCAA metabolism.

Sex Differences in Glucose and Fatty Acid Metabolism in Asians Who Are Nonobese

CONTEXT

The prevalence of diabetes is increasing throughout Asia, even in the absence of obesity, and is lower in women than in men. The underlying mechanisms are not well understood.

OBJECTIVE

To evaluate the sex differences in glucose and fatty acid metabolism in Asians who are nonobese.

DESIGN

Cross-sectional study.

SETTING

Clinical Nutrition Research Centre, Singapore.

PARTICIPANTS

Healthy Asian men (n = 32; body mass index, 21.8 ± 1.5 kg/m2; age, 42 ± 14 years) and women (n = 28; body mass index, 21.4 ± 2.0 kg/m2; age, 41 ± 13 years).

MAIN OUTCOME MEASURES

Insulin sensitivity (insulin-mediated glucose uptake normalized for steady-state insulin; hyperinsulinemic-euglycemic clamp), postprandial glucose, insulin and fatty acid concentrations, insulin secretion (mixed meal tolerance test with mathematical modeling), insulin clearance, body composition and fat distribution (dual-energy X-ray absorptiometry, MRI, and spectroscopy), cardiorespiratory fitness (maximal oxygen uptake; graded exercise test), and handgrip strength (dynamometry).

RESULTS

Women had more total body fat but less visceral fat than men; liver and muscle lipid contents were not different. Maximal oxygen uptake and handgrip strength were lower in women than men. The postprandial glucose concentrations were ~8% lower, the insulin-mediated glucose uptake was ~16% greater, and the meal-induced suppression of fatty acid concentrations was significantly greater in women than in men (P < 0.05 for all). However, muscle insulin sensitivity was not different between the sexes. No differences were found in postprandial insulin secretion and clearance rates; however, the steady-state insulin clearance was ~17% lower in women.

CONCLUSIONS

Asian women who are nonobese are more insulin-sensitive than men at the level of adipose tissue but not skeletal muscle. Therefore, sex differences in glucose tolerance are likely the result of sexual dimorphism in hepatic insulin action.

SEXUAL DIMORPHISM IN SELENIUM METABOLISM AND SELENOPROTEINS

Sexual dimorphism, the condition in which males and females in a species differ beyond the morphology of sex organs, delineates critical aspects of the biology of higher eukaryotes, including selenium metabolism. While sex differences in selenium biology have been described by several laboratories, delineation of the effects of sex in selenium function and regulation of selenoprotein expression is still in its infancy. This review encompasses the available information on sex-dependent parameters of selenium metabolism, as well as the effects of selenium on sex hormones. Gaps in the current knowledge of selenium and sex are identified and discussed.

Skeletal muscle ceramides and relationship with insulin sensitivity after 2 weeks of simulated sedentary behaviour and recovery in healthy older adults

KEY POINTS

Insulin sensitivity (as determined by a hyperinsulinaemic-euglyceamic clamp) decreased 15% after reduced activity. Despite not fully returning to baseline physical activity levels, insulin sensitivity unexpectedly, rebounded above that recorded before 2 weeks of reduced physical activity by 14% after the recovery period. Changes in insulin sensitivity in response to reduced activity were primarily driven by men but, not women. There were modest changes in ceramides (nuclear/myofibrillar fraction and serum) following reduced activity and recovery but, in the absence of major changes to body composition (i.e. fat mass), ceramides were not related to changes in inactivity-induced insulin sensitivity in healthy older adults.

ABSTRACT

Older adults are at risk of physical inactivity as they encounter debilitating life events. It is not known how insulin sensitivity is affected by modest short-term physical inactivity and recovery in healthy older adults, nor how insulin sensitivity is related to changes in serum and muscle ceramide content. Healthy older adults (aged 64-82 years, five females, seven males) were assessed before (PRE), after 2 weeks of reduced physical activity (RA) and following 2 weeks of recovery (REC). Insulin sensitivity (hyperinsulinaemic-euglyceamic clamp), lean mass, muscle function, skeletal muscle subfraction, fibre-specific, and serum ceramide content and indices of skeletal muscle inflammation were assessed. Insulin sensitivity decreased by 15 ± 6% at RA (driven by men) but rebounded above PRE by 14 ± 5% at REC. Mid-plantar flexor muscle area and leg strength decreased with RA, although only muscle size returned to baseline levels following REC. Body fat did not change and only minimal changes in muscle inflammation were noted across the intervention. Serum and intramuscular ceramides (nuclear/myofibrillar fraction) were modestly increased at RA and REC. However, ceramides were not related to changes in inactivity-induced insulin sensitivity in healthy older adults. Short-term inactivity induced insulin resistance in older adults in the absence of significant changes in body composition (i.e. fat mass) are not related to changes in ceramides.

Effect of Linagliptin and Voglibose on metabolic profile in patients with Type 2 Diabetes: a randomized, double-blind, placebo-controlled trial

Background

Dipeptidyl peptidase 4 (DPP4) inhibitors improve glycemic control by promoting GLP1-mediated glucose-dependent insulin secretion and suppression of glucagon. Sitagliptin and vildagliptin have been shown to improve insulin sensitivity in patients with type 2 diabetes mellitus (T2DM). However, these patients had uncontrolled blood glucose at inclusion; therefore, the improvement in insulin sensitivity observed in these studies could be attributed to the drug per se and/or reduction in glucotoxicity. This study examines the effect of linagliptin on insulin sensitivity and β-cell function in patients with well-controlled T2DM.

Methods

Thirty patients with T2DM of duration ≤5 years, and having HbA1c < 7.5% were randomized to receive linagliptin, voglibose or placebo (n = 10 each), and were followed up for 6 months. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp, and insulin secretory response was measured by basal (M₀) and postprandial (M₁) β-cell function, and area under curve (AUC) for C-peptide during mixed meal tolerance test.

Results

The median HbA1c of the study subjects at inclusion was 6.9% and there was no significant difference among the groups in terms of age, duration of diabetes, body mass index (BMI), HbA1c, insulin sensitivity, AUC of C-peptide and M₀ and M₁ at baseline. At the end of the study, there was a modest reduction in HbA1c (− 0.2%) in the linagliptin group, and a significant decrease (− 0.8%) in the voglibose group, as compared to placebo (p = 0.038). However, there were no significant differences in insulin sensitivity, M₀ and M₁ and AUC of C-peptide, within, or among the groups.

Conclusion

Linagliptin modestly improves glycemic profile in patients with well controlled T2DM; however, it may not have an effect on insulin sensitivity in these patients.

Trial registration

Retrospectively Registered in Clinicaltrials.gov (ID number, NCT02097342). Registered: March 27, 2014.

Balanced high fat diet reduces cardiovascular risk in obese women although changes in adipose tissue, lipoproteins, and insulin resistance differ by race

BACKGROUND

We previously reported that consuming a balanced high fat diet (BHFD) wherein total saturated fat was reduced and total unsaturated fat increased by proportionately balancing the type of fat (1/3 saturated, 1/3 monounsaturated, 1/3 polyunsaturated) led to significant improvements in inflammatory burden, blood pressure, and vascular function in obese premenopausal European American (EA) and African American (AA) women.

OBJECTIVE

Here we compared changes in adipose tissue, lipoproteins, insulin resistance, and cardiovascular risk between EA and AA women.

METHODS

Dietary intakes, plasma fatty acids, lipids, apolipoproteins, lipoproteins, HOMA-IR and ASCVD risk was measured in 144 women who consumed BHFD for 16 weeks. Generalized linear modeling was performed while controlling for change in body weight.

RESULTS

EA women had greater reductions in visceral adipose tissue. Only EA women had significant reductions in fasting insulin levels (↓24.8%) and HOMA-IR (↓29%) scores. In EA women, the most significant improvements occurred in VLDL particle size (↑), apolipoprotein B levels (↑), serum TG (↓), number of plasma LDL particles (↓), and serum LDL-cholesterol (↓). In AA women, significant improvements occurred in HDL particle size (↑), number of large HDL particles (↑), and apolipoprotein AI levels (↑). Consequently, both groups had improved ASCVD risk scores (↓5.5%).

CONCLUSIONS

Consuming the balanced high fat diet led to significant reduction in cardiovascular risk factors in both groups. However, the pattern of response to BHFD differed with EA women responding more in components of the apolipoprotein B pathway versus AA women responding more in components of the apolipoprotein AI pathway.

Gender differences in LDL- and HDL-cholesterol subfractions in patients after the acute ischemic stroke and their association with oxidative stress markers

The aim of our study was to examine gender differences of LDL- and HDL-cholesterol subfractions in patients after the acute ischemic stroke with focus on small LDL and HDL subfractions, and their association with oxidative stress markers. In addition, we have monitored the 7-day effect of cholesterol-lowering drugs administered to patients after the acute ischemic stroke, on these subfractions. Eighty two stroke patients and 81 age matched controls were included in this study. Blood was collected from patients within 24 h after the stroke (group A) and re-examined at the 7-day follow-up (group B). We have found gender differences in LDL- and HDL-subfractions in stroke patients, lipid-lowering drugs administered to acute ischemic stroke patients significantly reduced all measured parameters of lipoprotein profile. In the group A LDL1 subfraction positively correlated with activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) indicating a protective role of this subfraction. On the contrary, small HDL subfractions positively correlated with lipoperoxide levels and negatively with trolox equivalent antioxidant capacity in plasma suggesting a negative role of these subfractions. In this work we have confirmed the hypothesis of atherogenic properties of small HDL subfractions and anti-atherogenic properties of large LDL1-subfractions.

Fasting hepatic glucose uptake is higher in men than women

Differences in glucose metabolism between men and women have previously been reported. Our purpose was to determine if there is a gender difference in fasting hepatic glucose uptake (MRglu). Fifty‐five patients (44 men, 11 women) referred for routine PET/CT using the glucose tracer 2‐deoxy‐2‐[F‐18]fluoro‐D‐glucose (FDG), mainly for cancer, had dynamic imaging for 30 min immediately following injection. Hepatic FDG clearance (mL/min/100 mL) was measured as gradient divided by intercept from Patlak–Rutland graphical analysis using a volume of interest over the abdominal aorta to record input function. Hepatic MRglu was obtained by multiplication of clearance by blood glucose concentration. Hepatic steatosis was diagnosed as CT density ≤40 HU. Mean (standard deviation) hepatic MRglu in 44 men was 2.30 (1.14) μmol/min/100 mL, significantly higher than in 11 women in whom it was 1.07 (1.35) μmol/min/100 mL (P = 0.003). CT density was 52 (12) HU in women compared with 45 (9) HU in men (P = 0.04), but there was no significant difference in blood glucose, BMI, or prevalence of recent chemotherapy (within 6 months preceding PET/CT). When patients were subdivided into those without hepatic steatosis (31 men/9 women), those without evidence of FDG‐avid malignancy on PET/CT (15/6), and those without either (11/5), gender differences in hepatic MRglu remained highly significant, but there were no significant differences in CT density, blood glucose, BMI, or recent chemotherapy history. Despite this being a population of clinically referred patients, the results strongly suggest that fasting hepatic MRglu is higher in men than in women.

Weighted Gene Co-Expression Network Analysis Identifies Gender Specific Modules and Hub Genes Related to Metabolism and Inflammation in Response to an Acute Lipid Challenge

SCOPE

Inflammation is characteristic of diet-related diseases including obesity and type 2 diabetes (T2D). However, biomarkers of inflammation that reflect the early stage metabolic derangements are not optimally sensitive. Lipid challenges elicit postprandial inflammatory and metabolic responses. Gender-specific transcriptomic networks of the peripheral blood mononuclear cell (PBMC) were constructed in response to a lipid challenge.

METHODS AND RESULTS

Eighty-six adult males and females of comparable age, anthropometric, and biochemical profiles completed an oral lipid tolerance test (OLTT). PBMC transcriptome was profiled following OLTT. Weighted gene coexpression networks were constructed separately for males and females. Functional ontology analysis of network modules was performed and hub genes identified. Two modules of interest were identified in females-an "inflammatory" module and an "energy metabolism" module. NLRP3, which plays a central role in inflammation and STARD3 that is involved in cholesterol metabolism, were identified as hub genes for the respective modules.

CONCLUSION

The OLTT induced some gender-specific correlations of gene coexpression network modules. In females, biological processes relating to energy metabolism and inflammation pathways were evident. This suggests a gender specific link between inflammation and energy metabolism in response to lipids. In contrast, G-protein coupled receptor protein signaling pathway was common to both genders.

Effects of Local Use of Insulin on Wound Healing in Non-diabetic Patients

Background

Clinical trials have shown the positive effects of local insulin therapy in the formation of new vessels and fibrosis in acute and chronic diabetic wounds without major adverse effects.

Objective

The aim of this study was to investigate the effects of local insulin use on wound healing in non-diabetic patients.

Methods

A randomized, split-plot, double-blind, placebo-controlled trial was conducted. Ten non-diabetic patients with full-thickness acute wounds were recruited (5 due to trauma, 3 to burns, and 2 to pressure). All wounds received standard bedside treatment. Each wound was divided into 2 zones. One side received a standard care plus insulin, while the other received standard care plus injection of saline solution. A biopsy specimen was taken from both sites on days 0 and 14. The amount of blood vessel growth and the percentage of fibrosis were evaluated.

Results

A significant difference in the number of new vessels was observed on the insulin-treated site (70.6 [29.21]) compared to saline only (26.5 [34.3]; P < .04). The percentage of fibrosis (insulin 34.7 [28.02] vs saline 27.8 [29.9]) showed no significant difference. No adverse events related to the study occurred. The clinical implications of this study are considerable in terms of the formation of blood vessels but not fibrosis.

Conclusion

We suggest that local insulin administration is a safe therapeutic option for angiogenesis in wounds of non-diabetic patients.

Sexual dimorphism in oxidant-induced adaptive homeostasis in multiple wild-type D. melanogaster strains

Sexual dimorphism includes the physical and reproductive differences between the sexes, including differences that are conserved across species, ranging from the common fruit fly, Drosophila melanogaster, to humans. Sex-dependent variations in adaptive homeostasis, and adaptive stress responses may offer insight into the underlying mechanisms for male and female survival differences and into differences in chronic disease incidence and severity in humans. Earlier work showed sex-specific differences in adaptive responses to oxidative stressors in hybrid laboratory strains of D. melanogaster. The present study explored whether this phenomenon is also observed in wild-type D. melanogaster strains Oregon-R (Or-R) and Canton-S (Ca-S), as well as the common mutant reference strain w[1118], in order to better understand whether such findings are descriptive of D. melanogaster in general. Flies of each strain were pretreated with non-damaging, adaptive concentrations of hydrogen peroxide (H₂O₂) or of different redox cycling agents (paraquat, DMNQ, or menadione). Adaptive homeostasis, and changes in the expression of the Proteasome and overall cellular proteasomal proteolytic capacity were assessed. Redox cycling agents exhibited a male-specific adaptive response, whereas H₂O₂ exposure provoked female-specific adaptation. These findings demonstrate that different oxidants can elicit sexually dimorphic adaptive homeostatic responses in multiple fly strains. These results (and those contained in a parallel study [1]) highlight the need to address sex as a biological variable in fundamental science, clinical research, and toxicology.

Deletion of UCP1 enhances ex vivo aortic vasomotor function in female but not male mice despite similar susceptibility to metabolic dysfunction

Females are typically more insulin sensitive than males, which may be partly attributed to greater brown adipose tissue (BAT) activity and uncoupling protein 1 (UCP1) content. Accordingly, we tested the hypothesis that UCP1 deletion would abolish sex differences in insulin sensitivity and that whitening of thoracic periaortic BAT caused by UCP1 loss would be accompanied with impaired thoracic aortic function. Furthermore, because UCP1 exerts antioxidant effects, we examined whether UCP1 deficiency-induced metabolic dysfunction was mediated by oxidative stress. Compared with males, female mice had lower HOMA- and AT-insulin resistance (IR) despite no significant differences in BAT UCP1 content. UCP1 ablation increased HOMA-IR, AT-IR, and whitening of BAT in both sexes. Expression of UCP1 in thoracic aorta was greater in wild-type females compared with males. Importantly, deletion of UCP1 enhanced aortic vasomotor function in females only. UCP1 ablation did not promote oxidative stress in interscapular BAT. Furthermore, daily administration of the free radical scavenger tempol for 8 wk did not abrogate UCP1 deficiency-induced increases in adiposity, hyperinsulinemia, or liver steatosis. Collectively, we report that 1) in normal chow-fed mice housed at 25°C, aortic UCP1 content was greater in females than males and its deletion improved ex vivo aortic vasomotor function in females only; 2) constitutive UCP1 content in BAT was similar between females and males and loss of UCP1 did not abolish sex differences in insulin sensitivity; and 3) the metabolic disruptions caused by UCP1 ablation did not appear to be contingent upon increased oxidative stress in mice under normal dietary conditions.

Hypertriglyceridemia-waist and risk of developing type 2 diabetes: The Rural Chinese Cohort Study

Limited information is available on the effect of hypertriglyceridemia–waist (HTGW) combination and its dynamic status on the risk of type 2 diabetes mellitus (T2DM) in rural China. A cohort of 12,086 participants 18 to 92 years old was retained in this study. Kaplan-Meier analysis yielded the cumulative incidence of T2DM for each phenotype group (based on TG level and waist circumference [WC] at baseline). Cox regression yielded hazard ratios relating HTGW (based on TG level and WC at baseline and follow-up) to risk of developing T2DM. After a median follow-up of 6.0 years (71,432 person-years of follow-up), T2DM developed in 621 participants. For HTGW participants, the incidence of T2DM was 26.4/1000, 20.6/1000, and 21.9/1000 person-years for males, females, and overall, respectively. The adjusted HR for HTGW associated with T2DM was 7.63 (95% CI 4.32–13.49) for males and 7.75 (4.71–12.78) for females. Compared with consistent HTGW, with transformation from baseline HTGW to normal WC and normal triglycerides level at follow-up, the risk of developing T2DM was reduced by 75% and 78% for males and females. HTGW is a major risk factor for T2DM, but the risk could be reduced by improved triglycerides level and WC.

ANTHROPOMETRIC FEATURES ARE NOT PREDICTIVE OF 72-HOUR FAST DURATION IN INSULINOMAS

OBJECTIVE

The 72-hour fast is used to document Whipple's triad and understand the mechanism of hypoglycemia. Although hypoglycemia develops within 24 hours in the majority of fasts, identifying possible determinants of fast duration may help to predict the need for admission. Therefore, we determined the relation between anthropometric features on fast duration and assessed end of fast parameters on maximal tumor size, extent of disease, or tumor recurrence.

METHODS

A retrospective analysis of patients with insulinoma in the past 25 years who underwent a 72-hour fast was conducted. Electronic medical records were reviewed to obtain anthropometric patient data and tumor characteristics.

RESULTS

A total of 233 patients underwent the 72-hour fast. The mean age at diagnosis was 50 ± 16 years, with a body mass index (BMI) of 29 ± 7 kg/m², and 66% (153 of 233) were female. Duration of fast was not associated with gender (P = .2), age (P = .3), or BMI (P = .7). A shorter fast duration was inversely related to end of fast C-peptide (P = .0075) but not insulin (P = .13) or proinsulin (P = .28) concentration. End of fast C-peptide was associated with increased tumor size (P = .036) and multiplicity (P =.01). Proinsulin was associated with increased tumor size (P<.01) and malignancy (P = .018).

CONCLUSION

Duration of fast was not significantly related age, gender, weight, or BMI, although end-of-fast C-peptide and proinsulin may provide some information regarding tumor characteristics. Consequently, the duration of fast cannot be predicted a priori and should be allowed to run for the planned length unless hypoglycemia develops. Abbreviation: BMI = body mass index.

Use of the hyperinsulinemic euglycemic clamp to assess insulin sensitivity in guinea pigs: dose response, partitioned glucose metabolism, and species comparisons

The guinea pig is an alternate small animal model for the study of metabolism, including insulin sensitivity. However, only one study to date has reported the use of the hyperinsulinemic euglycemic clamp in anesthetized animals in this species, and the dose response has not been reported. We therefore characterized the dose-response curve for whole body glucose uptake using recombinant human insulin in the adult guinea pig. Interspecies comparisons with published data showed species differences in maximal whole body responses (guinea pig ≈ human < rat < mouse) and the insulin concentrations at which half-maximal insulin responses occurred (guinea pig > human ≈ rat > mouse). In subsequent studies, we used concomitant d-[3-³H]glucose infusion to characterize insulin sensitivities of whole body glucose uptake, utilization, production, storage, and glycolysis in young adult guinea pigs at human insulin doses that produced approximately half-maximal (7.5 mU·min^-1·kg^-1) and near-maximal whole body responses (30 mU·min^-1·kg^-1). Although human insulin infusion increased rates of glucose utilization (up to 68%) and storage and, at high concentrations, increased rates of glycolysis in females, glucose production was only partially suppressed (~23%), even at high insulin doses. Fasting glucose, metabolic clearance of insulin, and rates of glucose utilization, storage, and production during insulin stimulation were higher in female than in male guinea pigs (P < 0.05), but insulin sensitivity of these and whole body glucose uptake did not differ between sexes. This study establishes a method for measuring partitioned glucose metabolism in chronically catheterized conscious guinea pigs, allowing studies of regulation of insulin sensitivity in this species.

GLP-1 receptor agonists in the treatment of polycystic ovary syndrome

INTRODUCTION

Polycystic ovarian syndrome (PCOS) affects many women of child-bearing age and is characterized by hyperandrogenism, ovulatory and metabolic dysfunction. A primary treatment goal is weight reduction. The weight loss effects of glucagon-like peptide-1 receptor agonists (GLP-1RA), previously demonstrated in diabetic and obese non-diabetic patients, offer a unique opportunity to expand the medical options available to PCOS patients. Areas covered: Available clinical trials of glucagon-like peptide-1 receptor agonist therapy in PCOS were reviewed. Literature was searched from PubMed using appropriate search terms up to November 2016. Expert commentary: The available studies of GLP-1 RA therapy in the treatment of excess body weight in women with PCOS demonstrate that exenatide and liraglutide are effective in weight reduction either as monotherapy or in combination with metformin. A few studies showed that androgens may be modestly decreased and menstrual frequency may be increased. Eating behavior may be improved with liraglutide therapy. Glucose parameters are generally improved. GLP-1RAs were well-tolerated, with nausea being the most significant adverse side effect. Barriers to utilization may be the short duration studies, lack of familiarity of the medication, the route of administration (injection) and the variable outcomes on ovulation and hyperandrogenism.

The Mitochondrial Lon Protease Is Required for Age-Specific and Sex-Specific Adaptation to Oxidative Stress

Multiple human diseases involving chronic oxidative stress show a significant sex bias, including neurodegenerative diseases, cancer, immune dysfunction, diabetes, and cardiovascular disease. However, a possible molecular mechanism for the sex bias in physiological adaptation to oxidative stress remains unclear. Here, we report that Drosophila melanogaster females but not males adapt to hydrogen peroxide stress, whereas males but not females adapt to paraquat (superoxide) stress. Stress adaptation in each sex requires the conserved mitochondrial Lon protease and is associated with sex-specific expression of Lon protein isoforms and proteolytic activity. Adaptation to oxidative stress is lost with age in both sexes. Transgenic expression of transformer gene during development transforms chromosomal males into pseudo-females and confers the female-specific pattern of Lon isoform expression, Lon proteolytic activity induction, and H₂O₂ stress adaptation; these effects were also observed using adult-specific transformation. Conversely, knockdown of transformer in chromosomal females eliminates the female-specific Lon isoform expression, Lon proteolytic activity induction, and H₂O₂ stress adaptation and produces the male-specific paraquat (superoxide) stress adaptation. Sex-specific expression of alternative Lon isoforms was also observed in mouse tissues. The results develop Drosophila melanogaster as a model for sex-specific stress adaptation regulated by the Lon protease, with potential implications for understanding sexual dimorphism in human disease.

Plasma amino acid levels are elevated in young, healthy low birth weight men exposed to short-term high-fat overfeeding

Low birth weight (LBW) individuals exhibit a disproportionately increased, incomplete fatty acid oxidation and a decreased glucose oxidation, compared with normal birth weight (NBW) individuals, and furthermore have an increased risk of developing insulin resistance and type 2 diabetes. We hypothesized that changes in amino acid metabolism may occur parallel to alterations in fatty acid and glucose oxidation, and could contribute to insulin resistance. Therefore, we measured fasting plasma levels of 15 individual or pools of amino acids in 18 LBW and 25 NBW men after an isocaloric control diet and after a 5-day high-fat, high-calorie diet. We demonstrated that LBW and NBW men increased plasma alanine levels and decreased valine and leucine/isoleucine levels in response to overfeeding. Also, LBW men had higher alanine, proline, methionine, citrulline, and total amino acid levels after overfeeding compared with NBW men. Alanine and total amino acid levels tended to be negatively associated with the insulin-stimulated glucose uptake after overfeeding. Therefore, the higher amino acid levels in LBW men could be a consequence of their reduction in skeletal muscle insulin sensitivity due to overfeeding with a possible increased skeletal muscle proteolysis and/or could potentially contribute to an impaired insulin sensitivity. Furthermore, the alanine level was negatively associated with the plasma acetylcarnitine level and positively associated with the hepatic glucose production after overfeeding. Thus, the higher alanine level in LBW men could be accompanied by an increased anaplerotic formation of oxaloacetate and thereby an enhanced tricarboxylic acid cycle activity and as well an increased gluconeogenesis.

Sex differences in insulin sensitivity and insulin response with increasing age in black South African men and women

AIMS

Black Africans are disproportionally affected by type 2 diabetes, but the pathophysiology is poorly understood. The study aimed to examine the effect of sex and age on insulin sensitivity and insulin response in black South African adults.

METHODS

This cross-sectional study included a random sample of 179 men and 260 women aged 25-74years with normal glucose tolerance from 5 peri-urban townships in Cape Town, SA. Insulin sensitivity (insulin sensitivity index, ISI_0,120) and response (insulinogenic index, IGI), and the disposition index (DI, ISI_0,120×IGI), derived from an oral glucose tolerance test, were measured.

RESULTS

Although men were older (median [interquartile range]: 39 [30-48] vs. 35 [29-44], P=0.021) and had significantly lower BMI than women (22.6 [20.0-25.3] vs. 31.0 [25.9-35.7] kg/m², P=0.001), DI was not different (P=0.740), but ISI_0,120 was higher (P=0.007) and IGI was lower (P=0.074) in men than women, adjusting for age and BMI. With increasing age, DI (β (95%CI): -24.4 (-36.3 to -12.5), P<0.001) and IGI (β (95%CI): -4.9 (-7.5 to -2.2), P<0.001) decreased similarly in both sexes, but ISI_0,120 did not change (β (95%CI): 0.005 (-0.20 to 0.03), P=0.675).

CONCLUSION

Black South African women with normal glucose tolerance have lower insulin sensitivity than their male counterparts, but increase their insulin response to maintain normoglycemia. With increasing age, insulin sensitivity remains unchanged, but the insulin response decreases at a similar rate in men and women.

The relationship between cholesterol concentration and carotid intima media thickness differs according to gender and menopausal status in Korean type 2 diabetic patients

BACKGROUND

We investigated the associations between cardiometabolic factors and carotid intima media thickness (IMT) in Korea type 2 diabetes (T2DM) patients, and assessed the possible difference with respect to gender and menopausal status.

METHODS

We conducted a cross-sectional study with 1288 T2DM patients from the Department of Endocrinology and Metabolism at Gangnam Severance Hospital. Carotid IMT and various biochemical parameters were measured, and the postmenopausal status was assessed.

RESULTS

In partial correlation analysis, total cholesterol (TC) and LDL cholesterol (LDL-C) were positively correlated with right maximum IMT in men. For postmenopausal women, TC and LDL-C were positively correlated with IMT (all p<0.05) while no such correlation was observed in premenopausal women. In regression analysis, age was the most predominant factor for IMT in all 3 groups. For men, insulin and TC were predictive factors for maximum IMT (all p<0.05), and for postmenopausal women, TC and LDL-C were significant factors for mean and maximum IMT (all p<0.01). However, cholesterol concentrations were not related to all types of IMT in premenopausal women.

CONCLUSION

The association between LDL-C and carotid IMT seems to differ according to gender and menopausal status in T2DM patients.

Total cholesterol as a risk factor for coronary heart disease and stroke in women compared with men: A systematic review and meta-analysis

BACKGROUND

Raised total cholesterol is a strong risk factor for cardiovascular disease (CVD). It remains unknown whether sex differences exist in the relationship between total cholesterol and CVD outcomes.

METHODS

PubMed was searched in December 2014 for cohort studies reporting on the relationship between total cholesterol and coronary heart disease (CHD) and total stroke, separately in men and women. Random effects meta-analyses with inverse variance weighting were used to obtain adjusted pooled sex-specific relative risks (RR) and women-to-men ratio of RRs (RRRs).

RESULTS

Data from 97 cohorts, 1,022,276 individuals, and 20,176 CHD and 13,067 stroke cases were included. The pooled RR (95% confidence interval) for CHD associated with a 1-mmol/L increase in total cholesterol was 1.20 (1.16; 1.24) in women and 1.24 (1.20; 1.28) in men, resulting in a RRR of 0.96 (0.93; 0.99). Corresponding RRs for the risk of total stroke were 1.01 (0.98; 1.05) in women, and 1.03 (1.00; 1.05) in men, with a pooled RRR of 0.99 (0.93; 1.04). Pooled RRRs (95% CI) comparing individuals in the highest TC category to those in the lowest, such as the highest versus lowest third, were 0.87 (0.79; 0.96) for CHD and 0.86 (0.76; 0.97) for total stroke.

CONCLUSION

Raised total cholesterol is a strong risk factor for CHD, with evidence of a small, but significantly stronger, effect in men compared to women. Raised total cholesterol had little effect on the risk of total stroke in both sexes.