An intravenous insulin protocol designed for pregnancy reduces neonatal hypoglycaemia following betamethasone administration in women with gestational diabetes.

AIMS: Marked hyperglycaemia is common following betamethasone administration in women with gestational diabetes (GDM), and may contribute to neonatal hypoglycaemia. Validated protocols to deliver glycaemic stability following betamethasone are lacking. We hypothesized that an intravenous insulin (IVI) protocol for pregnancy-specific glycaemic targets (Pregnancy-IVI) would achieve greater at-target glycaemic control than a generic adult intravenous insulin protocol (Adult-IVI), and may reduce neonatal hypoglycaemia. METHODS: A retrospective cohort study of the performance Adult-IVI and Pregnancy-IVI following betamethasone in GDM, sequentially implemented at a tertiary hospital, without change in indication for IVI. Cases were identified by electronic record search. Primary outcome was percentage of on-IVI time with at-target glycaemia [blood glucose level (BGL) 3.8-7 mmol/l]. Secondary outcomes were time with critical hyperglycaemia (BGL > 10 mmol/l), occurrence of maternal hypoglycaemia (BGL < 3.8 mmol/l), and incidence of neonatal hypoglycaemia (BGL ≤ 2.5 mmol/l) if betamethasone was administered within 48 h of birth. RESULTS: The cohorts comprised 151 women (Adult-IVI n = 86; Pregnancy-IVI n = 65). The primary outcome was 68% time-at-target [95% confidence interval (CI) 64-71%) for Pregnancy-IVI compared with 55% (95% CI 50-60%) for Adult-IVI (P = 0.0002). Critical maternal hyperglycaemia (0% vs. 2%, P = 0.02) and hypoglycaemia (2% vs. 12%, P = 0.02) were both lower with Pregnancy-IVI than Adult-IVI. Neonatal hypoglycaemia was less common after Pregnancy-IVI (29%) than after Adult-IVI (54%, P = 0.03). A multiple logistic regression model adjusting for potential confounders gave an odds ratio for neonatal hypoglycaemia with Pregnancy-IVI of 0.27 (95% CI 0.10-0.76, P = 0.01). CONCLUSIONS: An IVI protocol designed for pregnancy effectively controlled maternal hyperglycaemia following betamethasone administration in GDM. This is the first intervention to show a reduction in betamethasone-associated neonatal hypoglycaemia, linked with optimum maternal glycaemic control.

Young children, adolescent girls and women with type 1 diabetes are more overweight and obese than reference populations, and this is associated with increased cardiovascular risk factors.

AIM: Overweight and obesity are frequently reported in young persons with type 1 diabetes, however its relative magnitude in comparison to the general population is not well understood. This study compared the prevalence of overweight and obesity in young persons with type 1 diabetes to a reference population and explored possible associated factors, including gender, age, HbA1c , insulin regimen, age at diagnosis, diabetes duration, socio-economic status and cardiovascular disease risk factors. METHODS: A cross-sectional review was undertaken of data collected from youth (3-17 years) in 2016 and young adults (18-30 years) in 2015 with a diagnosis of type 1 diabetes for > 3 months attending diabetes centres in Newcastle, Australia. Rates of overweight and obesity were compared with matched population survey results. RESULTS: Data from 308 youth and 283 young adults were included. In girls, significantly higher prevalence of overweight and obesity were seen in the 5-8 (43% vs. 18%), 13-16 (41% vs. 27%), 18-24 (46% vs. 34%) and 25-30 (60% vs. 43%) years age groups; whereas in boys increased prevalence was observed in the 5-8 years age group only (41% vs. 18%). Rates of overweight and obesity increased with age across sexes. In youth, BMI standard deviation score was correlated with socio-economic status, insulin regimen, blood pressure and blood lipids (P < 0.05). In adults, BMI was positively associated with blood pressure, and longer diabetes duration (P < 0.02). CONCLUSIONS: Overweight and obesity are over-represented in young persons with type 1 diabetes, particularly girls. As overweight is associated with other cardiovascular disease markers early intervention is paramount.

The duration of intrapartum maternal hyperglycaemia predicts neonatal hypoglycaemia in women with pre-existing diabetes.

AIM: There is a high incidence of neonatal hypoglycaemia in neonates born to mothers with pre-existing diabetes. This often necessitates admission to the neonatal intensive care. Guidelines suggest maintaining intrapartum blood glucose levels (BGLs) of 4-7 mmol/l in women with diabetes to reduce the risk of neonatal hypoglycaemia. This study assessed whether intrapartum BGLs in women with pre-gestational Type 1 and 2 diabetes were predictive of neonatal hypoglycaemia. METHODS: A retrospective analysis of 261 births delivered at a tertiary hospital in Australia from 2009 to 2014. RESULTS: There were 122 cases of neonatal hypoglycaemia (glucose ≤ 2.6 mmol/l) in 261 births (47%). The mothers in the neonatal hypoglycaemia group spent less time with BGL in the range 4-7 mmol/l [55 ± 37% vs. 65 ± 35%, P = 0.02; odds ratio (OR) 0.992, P = 0.03] and more time with BGL in the 7-10 mmol/l range (31 ± 34% vs. 18 ± 27%, P = 0.003; OR 1.013, P = 0.003) compared with those without neonatal hypoglycaemia. Although statistically significant, receiver operating characteristic (ROC) curve analysis showed that time spent with maternal BGLs in the range 4-7 mmol/l [area under the curve (AUC) = 0.58] or 7-10 mmol (AUC = 0.60) was not strong enough to be a useful clinical predictor of neonatal hypoglycaemia. HbA1c in the second trimester of pregnancy (P = 0.02, OR 1.42) and percentage time spent in BGL range of 7-10 mmol/l (P = 0.001, OR 1.02) were both associated with a risk of neonatal hypoglycaemia in a logistic regression model. HbA1c in the third trimester (P = 0.07, OR 1.28) approached, but did not reach, significance. CONCLUSIONS: These data support a BGL range of 4-7 mmol/l as an intrapartum target. Glycaemic control in the second trimester is associated with neonatal hypoglycaemia. Improvement in ante- and intrapartum glycaemic control may reduce neonatal hypoglycaemia in women with pre-existing diabetes.

Submillimetre galaxies reside in dark matter haloes with masses greater than 3 × 10(11) solar masses.

The extragalactic background light at far-infrared wavelengths comes from optically faint, dusty, star-forming galaxies in the Universe with star formation rates of a few hundred solar masses per year. These faint, submillimetre galaxies are challenging to study individually because of the relatively poor spatial resolution of far-infrared telescopes. Instead, their average properties can be studied using statistics such as the angular power spectrum of the background intensity variations. A previous attempt at measuring this power spectrum resulted in the suggestion that the clustering amplitude is below the level computed with a simple ansatz based on a halo model. Here we report excess clustering over the linear prediction at arcminute angular scales in the power spectrum of brightness fluctuations at 250, 350 and 500 µm. From this excess, we find that submillimetre galaxies are located in dark matter haloes with a minimum mass, M(min), such that log(10)[M(min)/M(⊙)] = 11.5(+0.7)(-0.2) at 350 µm, where M(⊙) is the solar mass. This minimum dark matter halo mass corresponds to the most efficient mass scale for star formation in the Universe, and is lower than that predicted by semi-analytical models for galaxy formation.

Proteomic and genomic evidence implicates the postsynaptic density in schizophrenia.

The postsynaptic density (PSD) contains a complex set of proteins of known relevance to neuropsychiatric disorders, and schizophrenia specifically. We enriched for this anatomical structure, in the anterior cingulate cortex, of 20 schizophrenia samples and 20 controls from the Stanley Medical Research Institute, and used unbiased shotgun proteomics incorporating label-free quantitation to identify differentially expressed proteins. Quantitative investigation of the PSD revealed more than 700 protein identifications and 143 differentially expressed proteins. Prominent among these were altered expression of proteins involved in clathrin-mediated endocytosis (CME) (Dynamin-1, adaptor protein 2) and N-methyl-D-aspartate (NMDA)-interacting proteins such as CYFIP2, SYNPO, SHANK3, ESYT and MAPK3 (all P<0.0015). Pathway analysis of the differentially expressed proteins implicated the cellular processes of endocytosis, long-term potentiation and calcium signaling. Both single-gene and gene-set enrichment analyses in genome-wide association data from the largest schizophrenia sample to date of 13,689 cases and 18,226 controls show significant association of HIST1H1E and MAPK3, and enrichment of our PSD proteome. Taken together, our data provide robust evidence implicating PSD-associated proteins and genes in schizophrenia, and suggest that within the PSD, NMDA-interacting and endocytosis-related proteins contribute to disease pathophysiology.

Cerebellothalamocortical pathway abnormalities in torsinA DYT1 knock-in mice.

The factors that determine symptom penetrance in inherited disease are poorly understood. Increasingly, magnetic resonance diffusion tensor imaging (DTI) and PET are used to separate alterations in brain structure and function that are linked to disease symptomatology from those linked to gene carrier status. One example is DYT1 dystonia, a dominantly inherited movement disorder characterized by sustained muscle contractions, postures, and/or involuntary movements. This form of dystonia is caused by a 3-bp deletion (i.e., ΔE) in the TOR1A gene that encodes torsinA. Carriers of the DYT1 dystonia mutation, even if clinically nonpenetrant, exhibit abnormalities in cerebellothalamocortical (CbTC) motor pathways. However, observations in human gene carriers may be confounded by variability in genetic background and age. To address this problem, we implemented a unique multimodal imaging strategy in a congenic line of DYT1 mutant mice that contain the ΔE mutation in the endogenous mouse torsinA allele (i.e., DYT1 knock-in). Heterozygous knock-in mice and littermate controls underwent microPET followed by ex vivo high-field DTI and tractographic analysis. Mutant mice, which do not display abnormal movements, exhibited significant CbTC tract changes as well as abnormalities in brainstem regions linking cerebellar and basal ganglia motor circuits highly similar to those identified in human nonmanifesting gene carriers. Moreover, metabolic activity in the sensorimotor cortex of these animals was closely correlated with individual measures of CbTC pathway integrity. These findings further link a selective brain circuit abnormality to gene carrier status and demonstrate that DYT1 mutant torsinA has similar effects in mice and humans.

A linear model for estimation of neurotransmitter response profiles from dynamic PET data.

The parametric ntPET model (p-ntPET) estimates the kinetics of neurotransmitter release from dynamic PET data with receptor-ligand radiotracers. Here we introduce a linearization (lp-ntPET) that is computationally efficient and can be applied to single scan data. lp-ntPET employs a non-invasive reference region input function and extends the LSRRM of Alpert et al. (2003) using basis functions to characterize the time course of neurotransmitter activation. In simulation studies, the temporal precision of neurotransmitter profiles estimated by lp-ntPET was similar to that of p-ntPET (standard deviation ~3 min for responses early in the scan) while computation time was reduced by several orders of magnitude. Violations of model assumptions such as activation-induced changes in regional blood flow or specific binding in the reference tissue have negligible effects on lp-ntPET performance. Application of the lp-ntPET method is demonstrated on [11C]raclopride data acquired in rats receiving methamphetamine, which yielded estimated response functions that were in good agreement with simultaneous microdialysis measurements of extracellular dopamine concentration. These results demonstrate that lp-ntPET is a computationally efficient, linear variant of ntPET that can be applied to PET data from single or multiple scan designs to estimate the time course of neurotransmitter activation.

Cue-induced dopamine release predicts cocaine preference: positron emission tomography studies in freely moving rodents.

Positron emission tomography studies in drug-addicted patients have shown that exposure to drug-related cues increases striatal dopamine, which displaces binding of the D(2) ligand, [(11)C]-raclopride. However, it is not known if animals will also show cue-induced displacement of [(11)C]-raclopride binding. In this study, we use [(11)C]-raclopride imaging in awake rodents to capture cue-induced changes in dopamine release associated with the conditioned place preference model of drug craving. Ten animals were conditioned to receive cocaine in a contextually distinct environment from where they received saline. Following conditioning, each animal was tested for preference and then received two separate [(11)C]-raclopride scans. For each scan, animals were confined to the cocaine and/or the saline-paired environment for the first 25 min of uptake, after which they were anesthetized and scanned. [(11)C]-raclopride uptake in the saline-paired environment served as a within-animal control for uptake in the cocaine-paired environment. Cocaine produced a significant place preference (p = 0.004) and exposure to the cocaine-paired environment decreased [(11)C]-raclopride binding relative to the saline-paired environment in both the dorsal (20%; p < 0.002) and ventral striatum (22%; p < 0.05). The change in [(11)C]-raclopride binding correlated with preference in the ventral striatum (R(2) = -0.87; p = 0.003). In this region, animals who showed little or no preference exhibited little or no change in [(11)C]-raclopride binding in the cocaine-paired environment. This noninvasive procedure of monitoring neurochemical events in freely moving, behaving animals advances preclinical molecular imaging by interrogating the degree to which animal models reflect the human condition on multiple dimensions, both biological and behavioral.

Differential effects of anesthetics on cocaine's pharmacokinetic and pharmacodynamic effects in brain.

Most studies of the effect of cocaine on brain activity in laboratory animals are preformed under anesthesia, which could potentially affect the physiological responses to cocaine. Here we assessed the effects of two commonly used anesthetics [alpha-chloralose (alpha-CHLOR) and isofluorane (ISO)] on the effects of acute cocaine (1 mg/kg i.v.) on cerebral blood flow (CBF), cerebral blood volume (CBV), and tissue hemoglobin oxygenation (S(t)O(2)) using optical techniques and cocaine's pharmacokinetics (PK) and binding in the rat brain using (PET) and [(11)C]cocaine. We showed that acute cocaine at a dose abused by cocaine abusers decreased CBF, CBV and S(t)O(2) in rats anesthetized with ISO, whereas it increased these parameters in rats anesthetized with alpha-CHLOR. Importantly, in ISO-anesthetized animals cocaine-induced changes in CBF and S(t)O(2) were coupled, whereas for alpha-CHLOR these measures were uncoupled. Moreover, the clearance of [(11)C]cocaine from the brain was faster for ISO (peak half-clearance 15.8 +/- 2.8 min) than for alpha-CHLOR (27.5 +/- 0.6 min), and the ratio of specific to non-specific binding of [(11)C]cocaine in the brain was higher for ISO- (3.37 +/- 0.32) than for alpha-CHLOR-anesthetized rats (2.24 +/- 0.4). For both anesthetics, cocaine-induced changes in CBF followed the fast uptake of [(11)C]cocaine in the brain (peaking at approximately 2.5-4 min), but only for ISO did the duration of the CBV and S(t)O(2) changes correspond to the rate of [(11)C]cocaine's clearance from the brain. These results demonstrate that anesthetics influence cocaine's hemodynamic and metabolic changes in the brain, and its binding and PK, which highlights the need to better understand the interactions between anesthetics and pharmacological challenges in brain functional imaging studies.

Racemic gamma vinyl-GABA (R,S-GVG) blocks methamphetamine-triggered reinstatement of conditioned place preference.

Preventing relapse poses a significant challenge to the successful management of methamphetamine (METH) dependence. Although no effective medication currently exists for its treatment, racemic gamma vinyl-GABA (R,S-GVG, vigabatrin) shows enormous potential as it blocks both the neurochemical and behavioral effects of a variety of drugs, including METH, heroin, morphine, ethanol, nicotine, and cocaine. Using the reinstatement of a conditioned place preference (CPP) as an animal model of relapse, the present study specifically investigated the ability of an acute dose of R,S-GVG to block METH-triggered reinstatement of a METH-induced CPP. Animals acquired a METH CPP following a 20-day-period of conditioning, in which they received 10 pairings of alternating METH and saline injections. During conditioning, rats were assigned to one of four METH dosage groups: 1.0, 2.5, 5.0, or 10.0 mg/kg (i.p., n = 8/group). Animals in all dosage groups demonstrated a robust and consistent CPP. This CPP was subsequently extinguished in each dosage group with repeated saline administration. Upon extinction, all groups reinstated following an acute METH challenge. On the following day, an acute dose of R,S-GVG (300 mg/kg, i.p.) was administered 2.5 h prior to an identical METH challenge. R,S-GVG blocked METH-triggered reinstatement in all four groups. Given that drug re-exposure may potentiate relapse to drug-seeking behavior, the ability of R,S-GVG to block METH-triggered reinstatement offers further support for its use in the successful management of METH dependence.

Initial comparison of ntPET with microdialysis measurements of methamphetamine-induced dopamine release in rats: support for estimation of dopamine curves from PET data.

A recently introduced mathematical method for extracting temporal characteristics of neurotransmitter release from dynamic positron emission tomography (PET) data was tested. The method was developed with the hope that by uncovering temporal information about neurotransmitter (nt) dynamics in PET data, researchers could shed new light on mechanisms of psychiatric diseases such as drug abuse and its treatment. In this study, we apply our model-based method, "ntPET", to (11)C-raclopride PET scans of rats in which the dopaminergic response to a microinfusion of methamphetamine in one striatum was assayed simultaneously by microdialysis and PET. Uptake of (11)C-raclopride into the untreated contralateral striatum was used as an input to the ntPET model. Direct comparisons of the model-based ntPET analysis and the microdialysis measurements confirmed that ntPET produced dopamine curves that were very similar in timing (takeoff and peak times) to the microdialysis curves. Variances in takeoff and peak times were comparable for the two methods. Neither method detected a false dopamine response to drug in a control animal. The high degree of correspondence between ntPET estimates and microdialysis measurements lends strong support to the idea that temporal information regarding dopamine release exists in dynamic (11)C-raclopride PET data and that it can be estimated reliably via ntPET. The method is entirely translatable to human PET imaging.

Subchronic racemic gamma vinyl-GABA produces weight loss in Sprague Dawley and Zucker fatty rats.

Given the growing obesity epidemic, pressure to develop an effective pharmacologic treatment is mounting. Following the completion of a randomized, double-blind, placebo controlled trial as well as two small open label trials, gamma vinyl-GABA (GVG) has been shown to be safe and effective for treating cocaine and/or methamphetamine dependence. In an extension of these findings, the present study examined whether GVG could produce weight loss in adolescent as well as genetically obese animals. Specifically, adolescent Sprague Dawley and adolescent and adult Zucker fatty rats received GVG at various doses (75-300 mg/kg, i.p., racemic) for treatment periods lasting no longer than 14 consecutive days. GVG produced significant weight loss in a dose dependent fashion in all groups. These effects were marked, as average decreases of 12-20% of original body weight were observed. These findings suggest that GVG may be useful as a treatment for obesity. Further, that these results occurred in genetically obese animals offers the possibility that GVG may even help manage severe obesity resulting from binge-eating, a disorder involving food consumption in a pattern similar to the compulsive drug-seeking behavior observed in cocaine and methamphetamine dependent subjects.

Optimizing experimental protocols for quantitative behavioral imaging with 18F-FDG in rodents.

UNLABELLED: Small-animal PET provides the opportunity to image brain activation during behavioral tasks in animal models of human conditions. The present studies aimed to simplify behavioral imaging procedures without a loss of quantitation by using an intraperitoneal route of administration (no cannulation, no anesthesia) and using a standardized uptake value (SUV) to reduce scan duration. METHODS: Sixteen animals with carotid artery cannulations were studied with 18F-FDG small-animal PET accompanied by serial arterial blood sampling. Ten of these animals were anesthetized and were inside the tomograph during 18F-FDG uptake, whereas 6 animals were awake in their home cages and scanned after 60 min of uptake. Of the 10 anesthetized animals, 6 received intraperitoneal 18F-FDG, whereas 4 received intravenous 18F-FDG, and all 6 awake animals received intraperitoneal 18F-FDG. Intravenously injected animals were positioned far enough inside the tomograph to obtain region-of-interest-based measures from the heart and the brain. In all animals, a full arterial input function and plasma glucose levels were obtained. To establish the optimal time during 18F-FDG uptake for blood sampling when using an SUV, a Patlak kinetic model was used to derive absolute rates of glucose metabolism and compared with SUVs calculated using different plasma points from the arterial input function. RESULTS: A single plasma point taken at 60 min after injection for intraperitoneal injections or 45 min after injection for intravenous injections provides a sensitive index of glucose metabolic rate with the highest correlation with data obtained from a fully quantitative input function. CONCLUSION: These studies support an experimental protocol in which animals can receive the 18F-FDG tracer injection intraperitoneally, away from the small-animal tomograph and with minimal impact on behavior. Further, animals can occupy the tomograph bed for a 10- to 30-min scan with a consequent increase in animal throughput.

Metabolic and behavioral deficits following a routine surgical procedure in rats.

To test the hypothesis that functional metabolic deficits observed following surgical brain injury are associated with changes in cognitive performance in rodents, we performed serial imaging studies in parallel with behavioral measures in control animals and in animals with surgical implants. Memory function was assessed using the novel object recognition (NOR) test, administered 3 days prior to and 3, 7, 14 and 56 days after surgery. At each time point, general locomotion was also measured. Metabolic imaging with 18F-fluorodeoxyglucose ([18F]FDG) occurred 28 and 58 days after surgery. Animals with surgical implants performed significantly worse on tests of object recognition, while general locomotion was unaffected by the implant. There was a significant decrease in glucose uptake after surgery in most of the hemisphere ipsilateral to the implant relative to the contralateral hemisphere. At both time points, the most significant metabolic deficits occurred in the primary motor cortex (-25%; p<0.001), sensory cortex (-15%, p<0.001) and frontal cortex (-12%; p<0.001). Ipsilateral areas further from the site of insertion became progressively worse, including the sensory cortex, dorsal striatum and thalamus. These data was supported by a voxel-based analysis of the PET data, which revealed again a unilateral decrease in [18F]FDG uptake that extended throughout the ipsilateral cortex and persisted for the duration of the 58-day study. Probe implantation in the striatum results in a widespread and long-lasting decline in cortical glucose metabolism together with a persistent, injury-related deficit in the performance of a cognitive (object recognition) task in rats.

Targeting the treatment of drug abuse with molecular imaging.

Although imaging studies in and of themselves have significant contributions to the study of human behavior, imaging in drug abuse has a much broader agenda. Drugs of abuse bind to molecules in specific parts of the brain in order to produce their effects. Positron emission tomography (PET) provides a unique opportunity to track this process, capturing the kinetics with which an abused compound is transported to its site of action. The specific examples discussed here were chosen to illustrate how PET can be used to map the regional distribution and kinetics of compounds that may or may not have abuse liability. We also discussed some morphological and functional changes associated with drug abuse and different stages of recovery following abstinence. PET measurements of functional changes in the brain have also led to the development of several treatment strategies, one of which is discussed in detail here. Information such as this becomes more than a matter of academic interest. Such knowledge can provide the bases for anticipating which compounds may be abused and which may not. It can also be used to identify biological markers or changes in brain function that are associated with progression from drug use to drug abuse and also to stage the recovery process. This new knowledge can guide legislative initiatives on the optimal duration of mandatory treatment stays, promoting long-lasting abstinence and greatly reducing the societal burden of drug abuse. Imaging can also give some insights into potential pharmacotherapeutic targets to manage the reinforcing effects of addictive compounds, as well as into protective strategies to minimize their toxic consequences.

Insulin resistance correlates with maculopathy and severity of retinopathy in young adults with Type 1 Diabetes Mellitus.

AIMS: To assess the relationship between insulin resistance (IR), retinopathy and maculopathy in young adults with Type 1 diabetes mellitus. METHODS: A cross-sectional study at a regional Australian tertiary hospital. Retinal pathology, assessed by colour fundus photography, was correlated with two surrogate measures of IR: estimated Glucose Disposal Rate (eGDR) and Insulin Sensitivity Score (ISS), where lower scores reflect greater IR. RESULTS: 107 patients were recruited, with mean age 24.7years, 53% male, and mean duration of disease 10.8years. Mean eGDR scores (5.6vs 8.0 p<0.001) and ISS (4.7vs 7.9, p<0.001) were lower in subjects having at least moderate non-proliferative diabetic retinopathy (NPDR; relative to nil/mild-NPDR). Similarly, mean eGDR (4.2vs 6.2, p=0.001) and ISS (3.8vs 6.1, p=0.003) were lower in patients with maculopathy. Multivariate logistic regression modelling was used to control for confounding. For retinopathy severity, a unit increase in eGDR or ISS (representing lower IR) was associated with a 50% decrease in odds of moderate-NPDR or worse (eGDR OR 0.5, 95%CI 0.32-0.77, p=0.002; ISS OR 0.49, 95%CI 0.29-0.84, p=0.01). A unit increase in eGDR or ISS was associated with a 46-56% decrease in odds of maculopathy (eGDR OR 0.54, 95%CI 0.37-0.81, p=0.003; ISS OR 0.44, 95%CI 0.22-0.88, p=0.02). CONCLUSIONS: IR correlates with more severe retinopathy in young adults with Type 1DM. This is the first description of a correlation between IR and maculopathy in Type 1DM, warranting further evaluation. Prospective studies examining whether reducing IR can improve microvascular complications are required.

Targeting the PI3K/Akt/mTOR signalling pathway in Cystic Fibrosis.

Deletion of phenylalanine 508 of the cystic fibrosis transmembrane conductance regulator (ΔF508 CFTR) is a major cause of cystic fibrosis (CF), one of the most common inherited childhood diseases. ΔF508 CFTR is a trafficking mutant that is retained in the endoplasmic reticulum (ER) and unable to reach the plasma membrane. Efforts to enhance exit of ΔF508 CFTR from the ER and improve its trafficking are of utmost importance for the development of treatment strategies. Using protein interaction profiling and global bioinformatics analysis we revealed mammalian target of rapamycin (mTOR) signalling components to be associated with ∆F508 CFTR. Our results demonstrated upregulated mTOR activity in ΔF508 CF bronchial epithelial (CFBE41o-) cells. Inhibition of the Phosphatidylinositol 3-kinase/Akt/Mammalian Target of Rapamycin (PI3K/Akt/mTOR) pathway with 6 different inhibitors demonstrated an increase in CFTR stability and expression. Mechanistically, we discovered the most effective inhibitor, MK-2206 exerted a rescue effect by restoring autophagy in ΔF508 CFBE41o- cells. We identified Bcl-2-associated athanogene 3 (BAG3), a regulator of autophagy and aggresome clearance to be a potential mechanistic target of MK-2206. These data further link the CFTR defect to autophagy deficiency and demonstrate the potential of the PI3K/Akt/mTOR pathway for therapeutic targeting in CF.

Attenuated peptide YY release in obese subjects is associated with reduced satiety.

The responses of the gut hormone peptide YY (PYY) to food were investigated in 20 normal-weight and 20 obese humans in response to six test meals of varying calorie content. Human volunteers had a graded rise in plasma PYY (R2 = 0.96; P < 0.001) during increasing calorific meals, but the obese subjects had a lower endogenous PYY response at each meal size (P < 0.05 at all levels). The ratio of plasma PYY(1-36) to PYY(3-36) was similar in normal-weight and obese subjects. The effect on food intake and satiety of graded doses of exogenous PYY(3-36) was also evaluated in 12 human volunteers. Stepwise increasing doses of exogenous PYY(3-36) in humans caused a graded reduction in food intake (R2 = 0.38; P < 0.001). In high-fat-fed (HF) mice that became obese and low-fat-fed mice that remained normal weight, we measured plasma PYY, tissue PYY, and PYY mRNA levels and assessed the effect of exogenous administered PYY(3-36) on food intake in HF mice. HF mice remained sensitive to the anorectic effects of exogenous ip PYY(3-36). Compared with low-fat-fed fed mice, the HF mice had lower endogenous plasma PYY and higher tissue PYY but similar PYY mRNA levels, suggesting a possible reduction of PYY release. Thus, fasting and postprandial endogenous plasma PYY levels were attenuated in obese humans and rodents. The PYY(3-36) infusion study showed that the degree of plasma PYY reduction in obese subjects were likely associated with decreased satiety and relatively increased food intake. We conclude that obese subjects have a PYY deficiency that would reduce satiety and could thus reinforce their obesity.

Metabolic correlates of toluene abuse: decline and recovery of function in adolescent animals.

RATIONALE: Children and adolescents will readily abuse household products that contain solvents such as toluene. It is likely that reinforcing exposures to toluene alter brain glucose metabolism. OBJECTIVE: Using an animal model of drug reinforcement, we sought to identify a metabolic signature of toluene abuse in the adolescent rodent brain. Small animal PET (microPET), in combination with the glucose analog radiotracer, (18)FDG, were used to evaluate the metabolic consequences of inhaled toluene. METHODS: The exposure protocol paralleled our previously established method for assessing the conditioned reinforcing effects of toluene (5,000 ppm) using the conditioned place preference (CPP) paradigm. Animals were scanned at baseline and 2 h after the last exposure. Follow-up (18)FDG scans occurred 1 day, 3 weeks, and 2 months later. RESULTS: After six pairings, 38% of the animals preferred the toluene paired chamber and 25% were averse. The immediate metabolic effect in toluene-exposed animals was a 20% decline in whole brain (18)FDG uptake. Twenty-four hours following the last exposure, the whole brain decline was 40%, and 2 months later, the decline was 30% of pretoluene levels. A region-by-region analysis demonstrated significant additional decreases in the pons, cerebellum, striatum, midbrain, temporal cortex, and hippocampus. Two months after toluene cessation, regions of complete metabolic recovery were the thalamus and cerebellum; however, the temporal cortex did not recover. CONCLUSIONS: Brain uptake of (18)FDG appears to be a useful tool for examining the metabolic impact of toluene abuse, which include a profound decline followed by region-specific recovery after cessation.

Serial microPET measures of the metabolic reaction to a microdialysis probe implant.

Despite the widespread use of chronic brain implants in experimental and clinical settings, the effects of these long-term procedures on brain metabolism and receptor expression remain largely unknown. Under the hypothesis that intracerebral microdialysis transiently alters tissue metabolism, we performed a series of 18FDG microPET scans prior to and following surgical implantation of microdialysis cannulae. Parallel microPET measures using the competitive dopamine (DA) D2 receptor antagonist, 11C-raclopride, provided an assay of DA stability in these same animals. 18FDG scans were performed prior to microdialysis cannulation and again at 2, 12, 24, 48, 120, 168, 360 and 500 h (0.2, 0.5, 1, 2, 5, 7, 15 and 25 days). Separate animals received a sham surgery and the control group had no surgical intervention. For the first 24 h (scans at 2, 12 and 24 h post-surgery) uptake was reduced in both hemispheres. However, by 48 h, contralateral uptake had returned to pre-surgical levels. The striking finding was that from 48 to 500 h, the microdialysis cannulation produced widespread ipsilateral reductions in 18FDG uptake that encompassed the entire hemisphere. Despite the extent and persistence of these reductions, 11C-raclopride binding and ECF DA concentrations remained stable.