Energetic driving forces are maintained in resting rat skeletal muscle after dietary creatine supplementation

The total creatine(TCr) pool of skeletal muscle is composed of creatine (Cr) andphosphocreatine (PCr). In resting skeletal muscle, the ratio ofPCr to TCr (PCr/TCr; PCr energy charge) is ~0.6-0.8, dependingon the fiber type. PCr/TCr is linked to the cellular free energy of ATPhydrolysis by the Cr kinase equilibrium. Dietary Cr supplementationincreases TCr in skeletal muscle. However, many previous studies havereported data indicating that PCr/TCr falls after supplementation,which would suggest that Cr supplementation alters the restingenergetic state of myocytes. This study investigated the effect of Crsupplementation on the energy phosphates of resting skeletal muscle.Male rats were fed either rodent chow (control) or chow supplementedwith 2% (wt/wt) Cr. After 2 wk on the diet, the gastrocnemius andsoleus muscles were freeze clamped and removed from anesthetizedanimals. Cr supplementation increased TCr, PCr, and Cr levels in thegastrocnemius by 20, 22, and 17%, respectively (P < 0.05). A numerical 6% higher mean soleus TCr in Cr-supplemented ratswas not statistically significant. All other energy phosphate concentrations, free energy of ATP hydrolysis, and PCr/TCr were notdifferent between the two groups in either muscle. We conclude that Crsupplementation simply increased TCr in fast-twitch rat skeletal musclebut did not otherwise alter resting cellular energetic state.

     

Maternal overnutrition suppresses the phosphorylation of 5'-AMP-activated protein kinase in liver, but not skeletal muscle, in the fetal and neonatal sheep

Epidemiological studies have shown that infants exposed to an increased supply of nutrients before birth are at increased risk of type 2 diabetes in later life. We have investigated the hypothesis that fetal overnutrition results in reduced expression and phosphorylation of the cellular fuel sensor, AMP-activated kinase (AMPK) in liver and skeletal muscle before and after birth. From 115 days gestation, ewes were fed either at or approximately 55% above maintenance energy requirements. Postmortem was performed on lamb fetuses at 139-141 days gestation (n = 14) and lambs at 30 days of postnatal age (n = 21), and liver and quadriceps muscle were collected at each time point. The expression of AMPKalpha1 and AMPKalpha2 mRNA was determined by quantitative RT-PCR (qRT-PCR). The abundance of AMPKalpha and phospho-AMPKalpha (P-AMPKalpha) was determined by Western blot analysis, and the proportion of the total AMPKalpha pool that was phosphorylated in each sample (%P-AMPKalpha) was determined. The ratio of AMPKalpha2 to AMPKalpha1 mRNA expression was lower in fetuses compared with lambs in both liver and muscle, independent of maternal nutrition. Hepatic %P-AMPKalpha was lower in both fetuses and lambs in the Overfed group and %P-AMPKalpha in the lamb liver was inversely related to plasma glucose concentrations in the first 24 h after birth (r = 0.73, P < 0.025). There was no effect of maternal overnutrition on total AMPKalpha or P-AMPKalpha abundance in liver or skeletal muscle. We have, therefore, demonstrated that AMPKalpha responds to signals of increased nutrient availability in the fetal liver. Suppression of hepatic AMPK phosphorylation may contribute to increased glucose production, and basal hyperglycemia, present in lambs of overfed ewes in early postnatal life.     

Placental restriction of fetal growth decreases IGF1 and leptin mRNA expression in the perirenal adipose tissue of late gestation fetal sheep

Placental restriction (PR) of fetal growth results in a low birth weight and an increased visceral fat mass in postnatal life. We investigated whether PR alters expression of genes that regulate adipogenesis [IGF1, IGF1 receptor (IGF1R), IGF2, IGF2R, proliferator-activated receptor-gamma, retinoid-X-receptor-alpha], adipocyte metabolism (lipoprotein lipase, G3PDH, GAPDH) and adipokine signaling (leptin, adiponectin) in visceral adipose tissue before birth. PR was induced by removal of the majority of endometrial caruncles in nonpregnant ewes before mating. Fetal blood samples were collected from 116 days gestation, and perirenal visceral adipose tissue (PAT) was collected from PR and control fetuses at 145 days. PAT gene expression was measured by quantitative RT-PCR. PR fetuses had a lower weight (PR 2.90 +/- 0.32 kg; control, 5.12 +/- 0.24 kg; P < 0.0001), mean gestational arterial Po(2) (P < 0.0001), plasma glucose (P < 0.01), and insulin concentrations (P < 0.02), than controls. The expression of IGF1 mRNA in PAT was lower in the PR fetuses (PR, 0.332 +/- 0.063; control, 0.741 +/- 0.083; P < 0.01). Leptin mRNA expression in PAT was also lower in PR fetuses (PR, 0.077 +/- 0.009; control, 0.115 +/- 0.013; P < 0.05), although there was no difference in the expression of other adipokine or adipogenic genes in PAT between PR and control fetuses. Thus, restriction of placental and hence, fetal substrate supply results in decreased IGF1 and leptin expression in fetal visceral adipose tissue, which may alter the functional development of the perirenal fat depot and contribute to altered leptin signaling in the growth-restricted newborn and the subsequent emergence of an increased visceral adiposity.     

Theories and Major Hypotheses in Ethnobotany

Ethnobotany has evolved from a discipline that largely documented the diversity of plant use by local people to one focused on understanding how and why people select plants for a wide range of uses. This progress has been in response to a repeated call for theory-inspired and hypothesis-driven research to improve the rigor of the discipline. Despite improvements, recent ethnobotanical research has overemphasized the use of quantitative ethnobotany indices and statistical methods borrowed from ecology, yet underemphasized the development and integration of a strong theoretical foundation. To advance the field of ethnobotany as a hypothesis-driven, theoretically inspired discipline, it is important to first synthesize the existing theoretical lines of research. We review and discuss 17 major theories and hypotheses in ethnobotany that can be used as a starting point for developing research questions that advance our understanding of people–plant interactions. For each theory or major hypothesis, we identify its primary predictions and testable hypotheses and then discuss how these predictions have been tested. Developing research to test these predictions will make significant contributions to the field of ethnobotany and create the critical mass of primary literature necessary to develop meta-analyses and to advance new theories in ethnobotany.     

Impact of periconceptional nutrition on maternal and fetal leptin and fetal adiposity in singleton and twin pregnancies

It has been proposed that maternal nutrient restriction may alter the functional development of the adipocyte and the synthesis and secretion of the adipocyte-derived hormone, leptin, before birth. We have investigated the effects of restricted periconceptional undernutrition and/or restricted gestational nutrition on fetal plasma leptin concentrations and fetal adiposity in late gestation. There was no effect of either restricted periconceptional or gestational nutrition on maternal or fetal plasma leptin concentrations in singleton or twin pregnancies during late gestation. In ewes carrying twins, but not singletons, maternal plasma leptin concentrations in late gestation were directly related to the change in ewe weight that occurred during the 60 days before mating [maternal leptin = 0.9 (change in ewe weight) + 7.8; r = 0.6, P < 0.05]. In twin, but not singleton, pregnancies, there was also a significant relationship between maternal and fetal leptin concentrations (maternal leptin = 0.5 fetal leptin + 4.2, r = 0.63, P < 0.005). The relative mass of perirenal fat was also significantly increased in twin fetal sheep in the control-restricted group (6.0 +/- 0.5) compared with the other nutritional groups (control-control: 4.1 +/- 0.4; restricted-restricted: 4.4 +/- 0.4; restricted-control: 4.3 +/- 0.3). In conclusion, the impact of maternal undernutrition on maternal plasma leptin concentrations during late gestation is dependent on fetal number. Furthermore, we have found that there is an increased fetal adiposity in the twins of ewes that experienced restricted nutrition throughout gestation, and this may be important in the programming of postnatal adiposity.     

Steroidogenic acute regulatory protein expression is decreased in the adrenal gland of the growth-restricted sheep fetus during late gestation

Functional development of the adrenal cortex is critical for fetal maturation and postnatal survival. In the present study, we have determined the developmental profile of expression of the mRNA and protein of an essential cholesterol-transporting protein, steroidogenic acute regulatory protein (StAR), in the adrenal of the sheep fetus. We have also investigated the effect of placental restriction (PR) on the expression of StAR mRNA and protein in the growth-restricted fetus. Adrenal glands were collected from fetal sheep at 82-91 days (n = 10), 125-133 days (n = 10), and 140-144 days (n = 9) and from PR fetuses at 141-145 days gestation (n = 9) (term = 147 +/- 3 days gestation). The adrenal StAR mRNA:18S rRNA increased (P < 0.05) between 125 days (7.44 +/- 1.61) and 141-144 days gestation (13.76 +/- 1.88). There was also a 13-fold increase (P < 0.05) in the amount of adrenal StAR protein between 133 and 144 days gestation in these fetuses. However, the amount of StAR protein (6.9 +/- 1.7 arbitrary densitometric units [AU]/microg adrenal protein) in the adrenal of the growth-restricted fetal sheep was significantly reduced, when compared with the expression of StAR protein (17.1 +/- 1.9 AU/microg adrenal protein) in adrenals from the age-matched control group. In summary, there is a developmental increase in the expression of StAR mRNA and protein in the fetal sheep adrenal during the prepartum period when adrenal growth and steroidogenesis is dependent on ACTH stimulation. We have found that, while the level of expression of StAR protein is decreased in the adrenal gland of the growth-restricted fetus during late gestation, this does not impair adrenal steroidogenesis. Our data also suggest that the stimulation of adrenal growth and steroidogenesis in the growth-restricted fetus may not be ACTH dependent.     

Obesity and weight loss result in increased adipose tissue ABCG1 expression in db/db mice

The prevalence of obesity has reached epidemic proportions and is associated with several co-morbid conditions including diabetes, dyslipidemia, cancer, atherosclerosis and gallstones. Obesity is associated with low systemic inflammation and an accumulation of adipose tissue macrophages (ATMs) that are thought to modulate insulin resistance. ATMs may also modulate adipocyte metabolism and take up lipids released during adipocyte lipolysis and cell death. We suggest that high levels of free cholesterol residing in adipocytes are released during these processes and contribute to ATM activation and accumulation during obesity and caloric restriction. Db/db mice were studied for extent of adipose tissue inflammation under feeding conditions of ad libitum (AL) and caloric restriction (CR). The major finding was a marked elevation in epididymal adipose ABCG1 mRNA levels with obesity and CR (6-fold and 16-fold, respectively) over that seen for lean wild-type mice. ABCG1 protein was also elevated for CR as compared to AL adipose tissue. ABCG1 is likely produced by cholesterol loaded ATMs since this gene is not highly expressed in adipocytes and ABCG1 expression is sterol mediated. Our data supports the concept that metabolic changes in adipocytes due to demand lipolysis and cell death lead to cholesterol loading of ATMs. Based on finding cholesterol-loaded peritoneal leukocytes with elevated levels of ABCG1 in CR as compared to AL mice, we suggest that pathways for cholesterol trafficking out of adipose tissue involve ATM egress as well as ABCG1 mediated cholesterol efflux. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).     

Application of AAO Matrix in Aligned Gold Nanorod Array Substrates for Surface-Enhanced Fluorescence and Raman Scattering

In this paper, we probed surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) from probe molecule Rhodamine 6G (R6G) on self-standing Au nanorod array substrates made using a combination of anodization and potentiostatic electrodeposition. The initial substrates were embedded within a porous alumina template (AAO). By controlling the thickness of the AAO matrix, SEF and SERS were observed exhibiting an inverse relationship. SERS and SEF showed a non-linear response to the removal of AAO matrix due to an inhomogeneous plasmon activity across the nanorod which was supported by FDTD calculations. We showed that by optimizing the level of AAO thickness, we could obtain either maximized SERS, SEF or simultaneously observe both SERS and SEF together.