Psychometric properties of measures for electronic cigarette dependence among former-smoking electronic cigarette users.

BACKGROUND: Measures designed to assess electronic cigarette (ECIG) dependence are largely adapted from those developed for cigarette smoking, and have been evaluated mainly among dual ECIG-cigarette users. The present study evaluated the psychometric properties of four dependence measures among former-smoking ECIG users. METHODS: Respondents (N = 187) were daily ECIG users who had formerly smoked cigarettes regularly. As part of an online survey, they completed four dependence measures: Penn State Electronic Cigarette Dependence Index (PSECDI); E-Cigarette Dependence Scale (EDS-4); Glover Nilsson Behavioral Questionnaire (GNBQ); and Diagnostic and Statistical Manual 5th Edition (DSM-5). RESULTS: Confirmatory factor analysis revealed a single factor structure for all four measures, and fit indices were adequate for all models. Most inter-item correlations (mean r's = 0.21 to 0.45) and all item-total correlations (mean r's = 0.53 to 0.80) were significant for all four measures. Internal consistency was highest for the GNBQ (α = 0.86) followed by the EDS-4 (α = 0.81), PSECDI (α = 0.76), and DSM-5 (α = 0.75). Age of ECIG initiation was correlated negatively with scores on the EDS-4 and DSM-5, while number of ECIG quit attempts was correlated positively with scores on all measures except the GNBQ. Convergent validity was highest for comparisons between the EDS-4 and PSECDI (r = 0.75) though all comparisons were significant (p's < 0.001). CONCLUSIONS: All four measures demonstrated acceptable reliability and validity in this sample of former-smoking ECIG users.

Lifespan Effects of Muscle-Specific Androgen Receptor Overexpression on Body Composition of Male and Female Rats.

Androgenic actions of gonadal testosterone are thought to be a major mechanism promoting sex differences in body composition across the lifespan. However, this inference is based on studies of androgen receptor (AR) function in late adolescent or emerging adult rodents. Here we assess body composition and AR expression in skeletal muscle of rats at defined ages, comparing wild-type (WT) to transgenic human skeletal actin-driven AR overexpression (HSAAR) rats which overexpress AR in skeletal muscle. Male and female HSAAR and WT Sprague Dawley rats (N = 288) underwent dual-energy x-ray absorptiometry (DXA) scanning and tissue collection at postnatal day (PND) 1, 10, 21, 42, 70, 183, 243, and 365. Expected sex differences in body composition and muscle mass largely onset with puberty (PND-21), with no associated changes to skeletal muscle AR protein. In adulthood, HSAAR increased tibialis anterior (TA) and extensor digitorum longus mass in males, and reduced the expected gain in gonadal fat mass in both sexes. In WT rats, AR protein was reduced in soleus, but not TA, throughout life. Nonetheless, soleus AR protein expression was greater in male rats than female rats at all ages of sexual development, yet only at PND-70 in TA. Overall, despite muscle AR overexpression effects, results are inconsistent with major sex differences in body composition during sexual development being driven by changes in muscle AR, rather suggesting that changes in ligand promote sexual differentiation of body composition during pubertal timing. Nonetheless, increased skeletal muscle AR in adulthood can be sufficient to increase muscle mass in males, and reduce adipose in both sexes.

Androgen action on myogenesis throughout the lifespan; comparison with neurogenesis.

Androgens' pleiotropic actions in promoting sex differences present not only a challenge to providing a comprehensive account of their function, but also an opportunity to gain insights by comparing androgenic actions across organ systems. Although often overlooked by neuroscientists, skeletal muscle is another androgen-responsive organ system which shares with the nervous system properties of electrochemical excitability, behavioral relevance, and remarkable capacity for adaptive plasticity. Here we review androgenic regulation of mitogenic plasticity in skeletal muscle with the goal of identifying areas of interest to those researching androgenic mechanisms mediating sexual differentiation of neurogenesis. We use an organizational-activational framework to relate broad areas of similarity and difference between androgen effects on mitogenesis in muscle and brain throughout the lifespan, from early organogenesis, through pubertal organization, adult activation, and aging. The focus of the review is androgenic regulation of muscle-specific stem cells (satellite cells), which share with neural stem cells essential functions in development, plasticity, and repair, albeit with distinct, muscle-specific features. Also considered are areas of paracrine and endocrine interaction between androgen action on muscle and nervous system, including mediation of neural plasticity of innervating and distal neural populations by muscle-produced trophic factors.

Longitudinal transitions in adolescent polytobacco use across waves 1-4 of the Population Assessment of Tobacco and Health study.

AIMS: This study aims to identify adolescent patterns of polytobacco use and measure transitions between patterns over time. DESIGN: Longitudinal analysis using data derived from waves 1-4 (2013-18) of the Population Assessment of Tobacco and Health (PATH) study. Transitions in tobacco use patterns were examined via latent transition analysis, and then, socio-demographic characteristics were used to predict transitions via logistic regression. SETTING: United States. PARTICIPANTS: Participants included 975 adolescents who used at least one tobacco product at any wave (W1 mean age = 13.29, standard deviation = 0.86; W4 54.2% male; 54.5% white, 25.9% Hispanic). MEASUREMENTS: Measurements included past 30-day use of cigarettes, electronic cigarettes (e-cigs), traditional cigars, cigarillos, filtered cigars, snus, smokeless tobacco (SLT) or hookah. FINDINGS: Six latent classes were identified. Cigarette users (43.5-58.8%) and SLT users (50.8-79.6%) tended to persist in their use over time. E-cig users began to probably transition to non-users (80.0%), but became more likely to persist in this use over time (31.1%). Non-users at a given wave were most likely to transition to e-cig users (8.5-43.7%) or cigarette users (6.7-28.6%). Cigarillo/poly-users and hookah/poly-users displayed more variable transition patterns. Adolescents were more likely to transition to non-use (versus become/remain e-cig users) if they were older (cigarette users, SLT users), younger (e-cig users), other race (SLT users), male (SLT users) or had less-educated parents (SLT users) compared with their counterparts. Hispanic (versus white) cigarette users were more likely to transition to non-users than to persist in this use. CONCLUSIONS: Among adolescents in the United States, patterns of tobacco use characterized by the use, mainly, of single, specific products appear to be stable, particularly by late adolescence. In contrast, patterns characterized by polytobacco use appear to be more variable and may represent experimentation without specialization.

Evaluation of the Psychometric Properties of Dependence Measures for Exclusive Electronic Cigarette Users.

INTRODUCTION: Extant electronic cigarette (ECIG) dependence measures are largely adapted from those designed for cigarette smoking, though few have been evaluated for their psychometric properties. AIMS AND METHODS: Never-smoking ECIG users (N = 134) participating in an online survey completed four dependence measures: Penn state electronic cigarette dependence index (PSECDI), e-cigarette dependence scale (EDS-4), diagnostic and statistical manual for tobacco use disorder (DSM-5), and Glover Nilsson behavioral questionnaire (GNBQ). They also reported on their ECIG use characteristics (eg, behaviors and reasons). RESULTS: Internal consistency was highest for the EDS-4 (Cronbach's α = 0.88) followed by the GNBQ (α = 0.75), PSECDI (α = 0.72), and DSM (α = 0.71). Confirmatory factor analyses revealed a single-factor structure for the PSECDI, EDS-4, and GNBQ. For the DSM-5, however, two items did not load significantly (ECIG use interferes with responsibilities; reduce/give up activities because of ECIG use). Significant correlations were observed between all measures and the number of ECIG use days/week and/or years using ECIGs, as well as between DSM-5 scores and the number of ECIG quit attempts and initiation age. Endorsement of using ECIGs because "I like flavors" was correlated positively with DSM-5 and GNBQ scores. CONCLUSIONS: All dependence measures evaluated herein demonstrated adequate reliability and construct validity. Future work should focus on determining which aspects of dependence are those that are unique to ECIG use, and subsequently developing a more comprehensive measure of ECIG dependence. IMPLICATIONS: The measures assessed herein-PSECDI, EDS-4, DSM-5, and GNBQ-demonstrated adequate to good reliability and construct validity among a sample of never-smoking ECIG users. The dependence domains covered across measures were related yet distinct. Findings demonstrate the need for future evaluation of these different domains to determine which are the most salient characteristics of ECIG dependence.

Predictors of electronic cigarette dependence among non-smoking electronic cigarette users: User behavior and device characteristics.

INTRODUCTION: ECIGs differ in their ability to deliver nicotine to the user and, consequently, they may differ in their ability to produce dependence. This study examined individual device characteristics, device type, and user behaviors as predictors of ECIG dependence in a sample of never-smoking ECIG users. METHODS: Participants (N = 134) completed an online survey that assessed demographics, ECIG use behavior, and ECIG dependence as measured via the Penn State Electronic Nicotine Dependence Index (PSECDI) and E-cigarette Dependence Scale (EDS-4). Participants uploaded a picture of their personal ECIG device/liquid, which was coded by raters to identify product features. Multivariable linear regressions examined device characteristics (e.g., adjustable power, nicotine concentration) and device type (e.g., vape pen, mod, pod, modern disposable) as predictors of dependence controlling for demographics and user behaviors (e.g., ECIG use duration and frequency, other tobacco use). RESULTS: Longer durations of ECIG use and more use days/week were associated significantly with higher PSECDI (ß's = 0.91 and 1.90, respectively; p's < 0.01) and EDS-4 scores (ß's = 0.16 and 0.28, respectively; p's < 0.01). Higher nicotine concentrations were associated with higher PSECDI scores only (ß = 0.07, p =.011). Dependence scores did not differ as a function of ECIG device types after controlling for covariates. CONCLUSIONS: ECIG dependence was observed among the never-smoking ECIG users in this sample, regardless of their ECIG device/liquid features. Findings suggest that regulatory efforts aimed at reducing the dependence potential of ECIGs in never smokers should focus on overall nicotine emissions rather than product features.

Myocytic androgen receptor overexpression does not affect sex differences in adaptation to chronic endurance exercise.

Muscle-specific androgen receptor (AR) overexpression (HSAAR transgene) in sedentary male rats results in reduced adiposity, increased mitochondrial enzyme activity, and selective increase in Type 2b myofiber size. Here, we tested chronic endurance exercise interactions with this phenotype in both sexes. Across 9 weeks, rats ran 5×/week on motorized running wheels at increasing speeds and durations. Exercise reduced fat mass in all groups, but sex affected endurance exercise outcomes such that absolute lean mass increased only in females and total body mass decreased only in males. Expected sex differences were observed with males exhibiting greater total body and lean mass; absolute and relative fat mass; bone mineral density; extensor digitorum longus (EDL) myofiber size and glycolytic proportion; but lesser Type 2a and Type 1 myosin expression in tibialis anterior. Observed HSAAR outcomes were not altered by sex, with transgenic rats having greater lean mass, Type 2a myosin expression in soleus, and glycolytic myofiber size in EDL. Tibialis AR content was independently affected by sex, HSAAR, and exercise. No sex differences were observed in tibialis AR expression in wild-type rats, although HSAAR males had greater AR content than HSAAR females. We identified a moderate correlation between AR expression and glycolytic myofiber size, but not whole-body composition. Overall, results suggest myocytic AR overexpression and chronic exercise, despite sharing a similar phenotype to adaptation, are mediated by distinct mechanisms. Further, this study illustrates sex differences in adaptation to chronic endurance exercise, and suggests sex-similarity in the relationship between muscle AR and exercise response.

Transitions in tobacco use profiles among adolescents: Results from the Population Assessment of Tobacco and Health (PATH) study waves 3 and 4.

INTRODUCTION: Despite increases in adolescents' polytobacco use, little work has utilized recent national data to examine transitions in polytobacco use over time or predictors of such transitions. METHODS: Data derived from the Population Assessment of Tobacco and Health (PATH) study. Participants used at least one tobacco product (cigarettes, electronic cigarettes [ECIGs], traditional cigars, cigarillos, filtered cigars, snus, smokeless tobacco [SLT], hookah) at Wave 3 (W3; 2015-2016) or 4 (W4; 2016-2018) and had Wave 1 (W1) data (N = 1072; Mage= 13.71, SD =1.71, 46.4% female; 56.6% White, 23.2% Hispanic). Latent transition analysis (LTA) examined probabilities of transitioning between classes across waves and sociodemographic correlates of transitions. RESULTS: Five latent classes were identified: Low Users (n = 372, 34.7% W3; n = 249, 23.3% W4), ECIG Users (n = 256, 23.8% W3; n = 286, 26.7% W4), Cigarette Users (n = 215, 20.1% W3; n = 293, 27.3% W4), SLT Users (n = 91, 8.5% W3; n = 92, 8.6% W4), and Polytobacco Users (n = 138, 12.9% W3; n = 152, 14.1% W4). Cigarette Users and SLT Users displayed the highest probabilities for class stability. Low Users were most likely to transition to ECIG Users or Cigarette Users, whereas Polytobacco Users were most likely to transition to Low Users. ECIG Users were likely to transition to Low Users or Cigarette Users. Older and White adolescents were more likely to display riskier transitions. CONCLUSIONS: Although Cigarette Users and SLT Users remained largely stable in membership, findings demonstrate greater movement across polytobacco use classes relative to previous research and suggest that ECIGs may be the most common entry point to tobacco use.

Geographic isolation predicts tobacco product use among youth: A latent class analysis.

PURPOSE: The purpose of the current study was to evaluate associations between geographic rurality and tobacco use patterns among adolescents. METHODS: High school students (N = 566) from north-central Appalachia reported on their lifetime and/or current use of cigarettes, electronic cigarettes (ECIGs), cigars, and smokeless tobacco. Geographic rurality was measured via the Isolation scale, whereby residential ZIP Codes determined the degree to which respondents have access to health-related resources. Latent class analysis (LCA) was used to identify discrete classes of adolescent tobacco users based on their use of tobacco products. Then, associations between participants' geographic rurality and class membership were evaluated using a series of multinomial logistic regressions. FINDINGS: LCA classified participants as Nonusers, Current ECIG Users, Cigarette/ECIG Experimenters, and Polytobacco Users. Individuals with higher Isolation scores were more likely to be Polytobacco Users and Cigarette/ECIG Experimenters than Nonusers, and were more likely to be Polytobacco Users than Current ECIG Users. CONCLUSIONS: The continuous Isolation scale used in the present study predicted polytobacco use patterns among adolescents in a manner that is consistent with, while simultaneously expanding upon, prior work. Tobacco control practices and policies should be viewed through a lens that considers the unique needs of geographically isolated areas.

Electronic Cigarette Terminology: Where Does One Generation End and the Next Begin?

IMPLICATIONS: The electronic cigarette (ECIG) research community faces several challenges when it comes to regulatory science; not only is the ECIG market changing at a rapid pace, but the terms used by researchers, health organizations, ECIG users, and ECIG manufacturers/distributors to describe devices are inconsistent. These discrepancies make it difficult to advance science and develop regulations. Although researchers have used "generations" to categorize ECIG device types based on various characteristics, with the constantly evolving ECIG market, it is unclear where one "generation" of devices ends and the next begins.

Device features and user behaviors as predictors of dependence among never-smoking electronic cigarette users: PATH Wave 4.

INTRODUCTION: Electronic cigarettes (ECIGs) vary greatly in their ability to deliver nicotine, which suggests they may also vary in their ability to produce dependence. This study examined individual and combined ECIG device features, and also user behaviors, as predictors of dependence in never-smoking ECIG users. Methods Data were collected from 711 current ECIG users who had smoked <100 cigarettes in their lifetime at Wave 4 of the Population Assessment of Tobacco and Health (PATH) Study. Multivariable linear regressions examined individual (e.g., contains nicotine, uses a tank, flavor preference) and combined (e.g., refillable tanks, refillable mods) device features, and user behaviors (e.g., uses/day) as predictors of dependence, withdrawal, and craving after accounting for demographic variables. Results Results for ECIG dependence and craving showed a similar pattern; higher levels were observed for older age, more frequent past 30-day use, using an ECIG containing nicotine (vs no nicotine), and using a non-refillable cartridge or refillable tank style (vs disposables). Higher withdrawal levels were observed for higher education levels and individual device features of tank (vs no tank), cartridge (vs no cartridge), refillable (vs non-refillable), and "other" flavor preference (vs tobacco flavor). Lower withdrawal levels were associated with a preference for sweet/fruit flavor(s) (vs tobacco flavor). Conclusions Few use behaviors and device features, whether examined alone or in combination, predicted dependence-related outcomes. Findings underscore the challenge with regulating ECIG products in the current marketplace, which is inundated with a myriad of device types.

Preliminary Evaluation of Short-Term Abstinence Effects Among Never-Smoking Experienced Users of Modern Electronic Cigarettes.

INTRODUCTION: ECIG use has increased among non-smokers, with the potential negative consequence of developing nicotine dependence. ECIG users report withdrawal symptoms upon abstinence, though the significance of these symptoms has been questioned. This preliminary study aimed to characterize the early timecourse of ECIG withdrawal under forced abstinence. METHODS: Fifteen never-smoking ECIG users completed two conditions whereby participants either abstained from ECIG use (abstinence) or used their own ECIG (ad lib) for 3 h. Puff topography in this latter condition was measured via video observation. Outcome measures included heart rate, subjective ratings of withdrawal, cognitive performance, and choice behavior. RESULTS: Heart rate was lower during abstinence compared to ad lib use (F = 12.60, p < .01, ƞp2 = 0.47). Higher levels of craving (F = 4.98, p < .05, ƞp2 = 0.26) and lower levels of nicotine effects (e.g., dizzy, F = 4.62, p < .05, ƞp2 = 0.36) were reported during abstinence compared to ad lib use. Interaction effects were observed for both factors of the Questionnaire of Smoking Urges: Brief (Fs > 3.56, ps < .05, ƞp2s = 0.21-0.27), with factor scores increasing from baseline to 90 min in the abstinent condition only. Inhibitory control was impaired at 120 min in the abstinent condition only (F = 7.51, p < .05, ƞp2 = 0.50). CONCLUSIONS: Never-smoking ECIG users experienced aversive withdrawal symptoms within 2-3 h of abstinence. Future work should include other control conditions, such as placebo ECIGs or nicotine replacement therapy, and biomarkers of nicotine exposure, as well as examine withdrawal as a function of device type. IMPLICATIONS: Never-smoking ECIG users experience some aversive nicotine withdrawal symptoms within two to three hours of abstinence. Relative to ad lib ECIG use, abstinence decreased heart rate and inhibitory control, as well as increased subjective ratings of withdrawal such as craving and intention to vape. Those same symptoms might be suppressed by self-administration of ECIGs. Experiencing withdrawal upon abstinence may indicate that ECIGs can cause dependence without a history of other tobacco use.

Evaluating and comparing the green wall retrofit suitability across major Australian cities.

Urban densification continues to present a unique set of economic and environmental challenges. A growing shortage of green space and infrastructure is intrinsically linked with urban growth and development. With this comes the loss of ecosystem services such as urban heat island effects, reduction of air quality and biodiversity loss. Vertical greenery systems (VGS) offer an adaptive solution to space-constrained areas that are characteristic of dense urban areas, and can potentially improve the sustainability of cities. However, in order to promote VGS uptake, methods are required to enable systematic appraisal of whether existing walls can be retrofitted with VGS. Further, feasibility studies that quantify the potential for retrofit suitability of VGS across entire urban areas are lacking. This study established an evaluation tool for green wall constructability in urban areas and validated the assessment tool by determining the quantity of walls in five major Australian cities that could potentially have VGS incorporated into the existing infrastructure. Each wall was analysed using an exclusionary set of criteria that evaluated and ranked a wall based on its suitability to VGS implementation. Sydney and Brisbane recorded the greatest proportional length of walls suitable for VGS, with 33.74% and 34.12% respectively. Conversely, Perth's urban centre was the least feasible site in which to incorporate VGS, with over 97% of surveyed walls excluded, mainly due to the prevalence of <1 m high fence lines and glazed shopfronts. This study aimed to evaluate feasibility assessments of green wall retrofitability in highly urbanised areas with the intention of creating an analytical method that is accessible to all. This method, coupled with the promising number of feasible walls found in this study, emphasises the need for more government policy and incentives encouraging green wall uptake and could play a pivotal role in the expansion of green infrastructure and urban forestry.

Cumulative disadvantage as a framework for understanding rural tobacco use disparities.

Traditional tobacco product (cigarettes and smokeless tobacco) and polytobacco use rates are significantly higher among rural adolescents and adults compared to their nonrural counterparts. Such disparities are due to several factors that promote tobacco use initiation and continuation, including individual-level psychopharmacological factors and structural-level factors such as fewer tobacco control efforts (e.g., fewer smoke-free policies and lower tobacco excise taxes), targeted tobacco marketing, less access to health-relevant resources, and more positive cultural norms surrounding tobacco use in rural communities. In this review, we use cumulative disadvantage theory as a framework for understanding how psychopharmacological and structural-level factors serve as drivers of tobacco use in rural areas. We start by describing how structural-level differences between rural-nonrural communities impact psychopharmacological influences and, when available, how these factors influence tobacco use. We conclude by discussing the interplay between factors, providing suggestions for ways to assess our application of cumulative disadvantage theory empirically and making recommendations for research and policy implementation in rural areas. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Does plant species selection in functional active green walls influence VOC phytoremediation efficiency?

Volatile organic compounds (VOCs) are of public concern due to their adverse health effects. Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms are not fully understood. This study assessed active botanical biofilters for their single-pass removal efficiency (SPRE) for benzene, ethyl acetate and ambient total volatile organic compounds (TVOCs), at concentrations of in situ relevance. Biofilters containing four plant species (Chlorophytum orchidastrum, Nematanthus glabra, Nephrolepis cordifolia 'duffii' and Schefflera arboricola) were compared to discern whether plant selection influenced VOC SPRE. Amongst all tested plant species, benzene SPREs were between 45.54 and 59.50%, with N. glabra the most efficient. The botanical biofilters removed 32.36-91.19% of ethyl acetate, with C. orchidastrum and S. arboricola recording significantly higher ethyl acetate SPREs than N. glabra and N. cordifolia. These findings thus indicate that plant type influences botanical biofilter VOC removal. It is proposed that ethyl acetate SPREs were dependent on hydrophilic adsorbent sites, with increasing root surface area, root diameter and root mass all associated with increasing ethyl acetate SPRE. The high benzene SPRE of N. glabra is likely due to the high wax content in its leaf cuticles. The SPREs for the relatively low levels of ambient TVOCs were consistent amongst plant species, providing no evidence to suggest that in situ TVOC removal is influenced by plant choice. Nonetheless, as inter-species differences do exist for some VOCs, botanical biofilters using a mixture of plants is proposed.

Determining broad scale associations between air pollutants and urban forestry: A novel multifaceted methodological approach.

Global urbanisation has resulted in population densification, which is associated with increased air pollution, mainly from anthropogenic sources. One of the systems proposed to mitigate urban air pollution is urban forestry. This study quantified the spatial associations between concentrations of CO, NO2, SO2, and PM10 and urban forestry, whilst correcting for anthropogenic sources and sinks, thus explicitly testing the hypothesis that urban forestry is spatially associated with reduced air pollution on a city scale. A Land Use Regression (LUR) model was constructed by combining air pollutant concentrations with environmental variables, such as land cover type and use, to develop predictive models for air pollutant concentrations. Traffic density and industrial air pollutant emissions were added to the model as covariables to permit testing of the main effects after correcting for these air pollutant sources. It was found that the concentrations of all air pollutants were negatively correlated with tree canopy cover and positively correlated with dwelling density, population density and traffic count. The LUR models enabled the establishment of a statistically significant spatial relationship between urban forestry and air pollution mitigation. These findings further demonstrate the spatial relationships between urban forestry and reduced air pollution on a city-wide scale, and could be of value in developing planning policies focused on urban greening.

Managing anabolic steroids in pre-hibernating Arctic ground squirrels: obtaining their benefits and avoiding their costs.

Androgens have benefits, such as promoting muscle growth, but also significant costs, including suppression of immune function. In many species, these trade-offs in androgen action are reflected in regulated androgen production, which is typically highest only in reproductive males. However, all non-reproductive Arctic ground squirrels, irrespective of age and sex, have high levels of androgens prior to hibernating at sub-zero temperatures. Androgens appear to be required to make muscle in summer, which, together with lipid, is then catabolized during overwinter. By contrast, most hibernating mammals catabolize only lipid. We tested the hypothesis that androgen action is selectively enhanced in Arctic ground squirrel muscle because of an upregulation of androgen receptors (ARs). Using Western blot analysis, we found that Arctic ground squirrels have AR in skeletal muscle more than four times that of Columbian ground squirrels, a related southern species that overwinters at approximately 0°C and has low pre-hibernation androgen levels. By contrast, AR in lymph nodes was equivalent in both species. Brain AR was also modestly but significantly increased in Arctic ground squirrel relative to Columbian ground squirrel. These results are consistent with the hypothesis that tissue-specific AR regulation prior to hibernation provides a mechanism whereby Arctic ground squirrels obtain the life-history benefits and mitigate the costs associated with high androgen production.

Glutamine reduces postprandial glycemia and augments the glucagon-like peptide-1 response in type 2 diabetes patients.

Impaired glucagon-like peptide (GLP-1) secretion or response may contribute to ineffective insulin release in type 2 diabetes. The conditionally essential amino acid glutamine stimulates GLP-1 secretion in vitro and in vivo. In a randomized, crossover study, we evaluated the effect of oral glutamine, with or without sitagliptin (SIT), on postprandial glycemia and GLP-1 concentration in 15 type 2 diabetes patients (glycated hemoglobin 6.5 ± 0.6%). Participants ingested a low-fat meal (5% fat) after receiving either water (control), 30 g l-glutamine (Gln-30), 15 g L-glutamine (Gln-15), 100 mg SIT, or 100 mg SIT and 15 g L-glutamine (SIT+Gln-15). Studies were conducted 1-2 wk apart. Blood was collected at baseline and postprandially for 180 min for measurement of circulating glucose, insulin, C-peptide, glucagon, and total and active GLP-1. Gln-30 and SIT+Gln-15 reduced the early (t = 0-60 min) postprandial glycemic response compared with control. All Gln treatments enhanced the postprandial insulin response from t = 60-180 min but had no effect on the C-peptide response compared with control. The postprandial glucagon concentration was increased by Gln-30 and Gln-15 compared with control, but the insulin:glucagon ratio was not affected by any treatment. In contrast to Gln-30, which tended to increase the total GLP-1 AUC, SIT tended to decrease the total GLP-1 AUC relative to control (both P = 0.03). Gln-30 and SIT increased the active GLP-1 AUC compared with control (P = 0.008 and P = 0.01, respectively). In summary, Gln-30 decreased the early postprandial glucose response, enhanced late postprandial insulinemia, and augmented postprandial active GLP-1 responses compared with control. These findings suggest that glutamine may be a novel agent for stimulating GLP-1 concentration and limiting postprandial glycemia in type 2 diabetes.

Androgen receptor and Kennedy disease/spinal bulbar muscular atrophy.

Kennedy Disease/Spinal Bulbar Muscular Atrophy (KD/SBMA) is a progressive neurodegenerative disease caused by genetic polyglutamine expansion of the androgen receptor. We have recently found that overexpression of wildtype androgen receptor in skeletal muscle of transgenic mice results in a KD/SBMA phenotype. This surprising result challenges the orthodox view that KD/SBMA requires expression of polyglutamine expanded androgen receptor within motoneurons. Theories relating to the etiology of this disease drawn from studies of human patients, cellular and mouse models are considered with a special emphasis on potential myogenic contributions to as well as the molecular etiology of KD/SBMA.