Cardioid oscillator-based pattern generator for imitating the time-ratio-asymmetrical behavior of the lower limb exoskeleton.

Introduction: Periodicity, self-excitation, and time ratio asymmetry are the fundamental characteristics of the human gait. In order to imitate these mentioned characteristics, a pattern generator with four degrees of freedom is proposed based on cardioid oscillators developed by the authors. Method: The proposed pattern generator is composed of four coupled cardioid oscillators, which are self-excited and have asymmetric time ratios. These oscillators are connected with other oscillators through coupled factors. The dynamic behaviors of the proposed oscillators, such as phase locking, time ratio, and self-excitation, are analyzed via simulations by employing the harmonic balance method. Moreover, for comparison, the simulated trajectories are compared with the natural joint trajectories measured in experiments. Results and discussion: Simulation and experimental results show that the behaviors of the proposed pattern generator are similar to those of the natural lower limb. It means the simulated trajectories from the generator are self-excited without any additional inputs and have asymmetric time ratios. Their phases are locked with others. Moreover, the proposed pattern generator can be applied as the reference model for the lower limb exoskeleton controlling algorithm to produce self-adjusted reference trajectories.

Preparation of a novel Bi9O7.5S6/SnS composite film with improved photoelectric properties.

Atomically thin two-dimensional (2D) bismuth oxychalcogenides have been considered as promising candidates for high-speed and low-power photoelectronic devices due to their high charge carrier mobility and excellent environmental stability. However, the photoelectric performance of their bulk materials still falls short of expectations. Herein, a novel Bi9O7.5S6/SnS composite film with a type-II heterojunction was successfully prepared by combining hydrothermal and knife-coating techniques. The crystal structure, morphology, and optical properties were systematically investigated. Under 1 V bias voltage, the photocurrent of the Bi9O7.5S6/SnS composite film can be obtained as 107 µA cm-2, which is about 29.9 times and 93.9 times higher than that of bare Bi9O7.5S6 and SnS, respectively. The type-II heterojunction has played a significant role in improving the photoelectric performance of the Bi9O7.5S6/SnS composite film by facilitating the separation and transfer of photo-generated carriers. This work sheds light on the design and development of new bismuth-based composite materials for advanced photoelectric and photocatalytic applications.

PEGylated Recombinant Human Growth Hormone Jintrolong® Exhibits Good Long-Term Safety in Cynomolgus Monkeys and Human Pediatric Growth Hormone Deficiency Patients.

Jintrolong® is a long-acting PEGylated recombinant human growth hormone (PEG-rhGH) developed for weekly injection in patients with pediatric growth hormone deficiency (PGHD). Although PEG modification of therapeutic proteins is generally considered safe, concerns persist about the potential for adverse vacuolation in tissues with long-term exposure to PEG-included therapies, particularly in children. We assessed the safety of Jintrolong® in cynomolgus monkeys with an examination of vacuolation in the brain choroid plexus (CP) and reported long-term clinical safety data obtained from children with PGHD. The toxicity of Jintrolong® was assessed following the 52-week administration with doses at 0.3, 1, or 3 mg/kg/week. The levels of vacuolation of CP in animals were dose-dependent and at least partially reversible after a 104- or 157-week recovery period. Vacuolation in the CP epithelium did not lead to obvious subcellular structural or cell functional abnormalities. Compared with the clinical dose of 0.2 mg/kg/week Jintrolong® in PGHD patients, exposure in monkeys under NOAEL 3 mg/kg/week exhibited safety margins greater than 120.5, the predicted minimum dose to induce vacuolation in monkeys is equivalent to 1.29 mg/kg/week in humans, which is 6.45-fold higher than the clinical dose. The safety data acquired in clinical trials for Jintrolong® were also analyzed, which included phase III (360 patients), phase IV (3,000 patients) of 26-week treatment, and a follow-up study with treatment lasting for 3 years. There was no statistically significant difference in the incidence of adverse reactions between the Jintrolong® group and the daily rhGH control group (no PEG), and no new adverse effects (AE) were observed in the Jintrolong® group at the clinical therapeutic dose of 0.2 mg/kg/week.

The Study of Magnetoimpedance Effect for Magnetoelectric Laminate Composites with Different Magnetostrictive Layers.

The rectangular magnetoelectric (ME) composites of Metglas/PZT and Terfenol-D/PZT are prepared, and the effects of a magnetostrictive layer's material characteristics on the magnetoimpedance of ME composite are discussed and experimentally investigated. The theoretical analyses show that the impedance is not only dependent on Young's modulus and the magnetostrictive strain of magnetostrictive material but is also influenced by its relative permeability. Compared with Terfenol-D, Metglas possesses significantly higher magnetic permeability and larger magnetostrictive strain at quite low Hdc due to the small saturation field, resulting in the larger magnetoimpedance ratio. The experimental results demonstrate that the maximum magnetoimpedance ratios (i.e., ΔZ/Z) of Metglas/PZT composite are about 605.24% and 239.98% at the antiresonance and resonance, respectively. Specifically, the maximum ΔZ/Z of Metglas/PZT is 8.6 times as high as that of Terfenol-D/PZT at the antiresonance. Such results provide the fundamental guidance in the design and fabrication of novel multifunction devices based on the magnetoimpedance effect of ME composites.

Enhanced peroxymonosulfate activation over heterogeneous catalyst Cu0.76Co2.24O4/SBA-15 for efficient degradation of sulfapyridine antibiotic.

The largest source of resistant bacteria or viruses is the overuse and misuse of antibiotics in humans and animals. These resistant bacteria or viruses may evolve into superbacteria or superviruses, which causes global plague. Therefore, it is significant to find a highly efficiency and low-cost method to eliminate antibiotics in water environment from inappropriate discharge. Here, a highly active and highly stable heterogeneous catalyst, Cu0.76Co2.24O4/SBA-15 (CCS) was prepared for peroxymonosulfate (PMS) activation in aim of decomposing persistent sulfapyridine (SPD). The reaction mechanism was thoroughly investigated via in situ quenching test and in situ electron paramagnetic resonance. Four reactive species, SO4·-, O2·-, 1O2 and ·OH were generated in Cu0.76Co2.24O4/SBA-15/PMS (CCSP) system. The SO4·- and O2·- were dominant active species responsible for SPD degradation. Co(Ⅱ)↔Co(Ⅲ)↔Co(Ⅱ) redox reaction cycle was constructed due to the different redox potential of Co(Ⅱ)/Co(Ⅲ), HSO5-/SO4∙-, and HSO5-/SO5∙-. Interestingly, Cu(Ⅰ) could urge the redox reaction cycle for PMS activation to be more thermodynamically feasible. Therefore, CCS possessed a highly catalytic activity and excellent stability. Meanwhile, the anions interference test indicated Cl-, NO3-, HCO3-, and H2PO4- had almost no inhibitory effect on SPD degradation over this catalytic system. We sincerely expected that this catalyst system would be applied extensively into antibiotics degradation in real water bodies.

Observational study evaluating the effectiveness of physician-targeted education for improving glycemic management of patients with type 2 diabetes (BEYOND II).

BACKGROUND: Because there has been no quality improvement initiatives targeting patients with type 2 diabetes (T2D) receiving basal insulin therapy, this study evaluated the effectiveness of physician-targeted education for optimizing glycemic management in these patients in China. METHODS: This multicenter open-label observational study conducted across China had a baseline sample survey, followed by a 6-month education program, and ended with a post-education sample survey. Education based on T2D treatment guidelines was given at Months 1 and 3, and was reinforced by self-audit every month. Each hospital enrolled 100 patients with T2D receiving basal insulin at both the baseline and post-education survey. The primary outcome was the proportion of hospitals meeting individual improvement goals. The goal setting was based on the proportion of patients achieving HbA1c <7.0% in each hospital at the time of the baseline survey. RESULTS: Overall, the individual improvement goal was achieved by 35 centers (49%). Hospitals with poor glycemic management at the baseline survey had higher possibility to improve at post-education survey. Two large sample surveys at baseline and post-education showed improved glucose management among these hospitals. A higher proportion of patients achieved HbA1c <7.0% in the post-education survey (27.2% vs 36.5%; P < 0.001) with reduced HbA1c levels (8.10% vs 7.72%; P < 0.001). Questionnaires from 723 physicians showed that confidence and practice of basal insulin use were significantly improved. CONCLUSIONS: Physician-targeted education improved glycemic management of patients with T2D in 71 hospitals in China, and was more effective at hospitals with poor glycemic management at the baseline survey.

Central pattern generator-based coupling control method for synchronously controlling the two-degrees-of-freedom robot.

Synchronous control is a fundamental and significant problem for controlling a multi-joint robot. In this article, by applying two coupled Rayleigh oscillators as the referred central pattern generator models for the two joints of a two-degrees-of-freedom robot, the central pattern generator-based coupling control method is proposed for controlling the two-degrees-of-freedom robot's joints. On these bases, the co-simulation model of the two-degrees-of-freedom robot with the proposed central pattern generator-based coupling control method is established via ADAMS and MATLAB/Simulink, and the performance of the central pattern generator-based coupling control method on synchronizing two motions of two-degrees-of-freedom robot's joints is numerically simulated. Furthermore, the experimental setup of a two-degrees-of-freedom robot is established based on the real-time simulations system via the proposed central pattern generator-based coupling control method. And experiments are carried out on the established setup. Simulations and experimental results show that the phase of the controlled two-degrees-of-freedom robot's joints is mutual locked to other, and their motion pattern can be adjusted through the coupling parameter in the central pattern generator-based coupling control method. In conclusion, the proposed central pattern generator-based coupling control method can control the two-degrees-of-freedom robot's joints to produce the coordinated motions and adjust the rhythmic pattern of the two-degrees-of-freedom robot.

A 5 g Inertial Micro-Switch with Enhanced Threshold Accuracy Using Squeeze-Film Damping.

Our previous report based on a 10 g (gravity) silicon-based inertial micro-switch showed that the contact effect between the two electrodes can be improved by squeeze-film damping. As an extended study toward its potential applications, the switch with a large proof mass suspended by four flexible serpentine springs was redesigned to achieve 5 g threshold value and enhanced threshold accuracy. The impact of the squeeze-film damping on the threshold value was theoretically studied. The theoretical results show that the threshold variation from the designed value due to fabrication errors can be reduced by optimizing the device thickness (the thickness of the proof mass and springs) and then establishing a tradeoff between the damping and elastic forces, thus improving the threshold accuracy. The design strategy was verified by FEM (finite-element-method) simulation and an experimental test. The simulation results show that the maximum threshold deviation was only 0.15 g, when the device thickness variation range was 16⁻24 µm, which is an adequately wide latitude for the current bulk silicon micromachining technology. The measured threshold values were 4.9⁻5.8 g and the device thicknesses were 18.2⁻22.5 µm, agreeing well with the simulation results. The measured contact time was 50 µs which is also in good agreement with our previous work.

Does selective logging change ground-dwelling beetle assemblages in a subtropical broad-leafed forest of China?

Selective logging with natural regeneration is advocated as a near-to-nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground-dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad-leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem-exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re-initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground-dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles.

Assessment of three fasting plasma glucose targets for insulin glargine-based therapy in people with type 2 diabetes mellitus in China: study protocol for a randomized controlled trial.

BACKGROUND: A large proportion of patients with T2DM in China do not meet accepted HbA1c targets despite the availability of guidelines that describe a treatment pathway for achieving glycemic control. The aim of this study is to identify the fasting plasma glucose (FPG) target that will provide the highest control rate of HbA1c <7 % in Chinese patients with T2DM treated with an insulin glargine-based regimen as an adjunct to an established OAD regimen. This information will support improvements in diabetes care management in China. METHODS: Approximately 934 men and women aged ≥18 to ≤65 years with poorly controlled T2DM will be enrolled and randomized to one of three FPG target groups; ≤5.6 mmol/L, ≤6.1 mmol/L, or ≤7.0 mmol/L. They will be initiated on daily insulin glargine (Lantus®) in addition to their usual OAD regimen for 24 weeks. Patients will self-monitor fasting blood glucose (SM-FBG), and the study physician will titrate the basal insulin dose according to the SM-FBG results. In addition, HbA1c and safety will be recorded. We plan to statistically derive the optimal FPG target for an HbA1c of <7 %. DISCUSSION: In China, treatment strategies that would achieve an optimum balance between glycemic control (as per HbA1c) and hypoglycemia are imperative to ensure improvements in the management of T2DM. Furthermore, elucidating the contribution of FPG to HbA1c in Chinese patients with T2DM and identifying a predictable relationship between FPG and HbA1c would be a valuable tool for patient self-management of diabetes. TRIAL REGISTRATION: NCT02545842 . Registered on 8 September 2015.

The Relative Importance of Spatial and Local Environmental Factors in Determining Beetle Assemblages in the Inner Mongolia Grassland.

The aim of this paper is to increase understanding of the relative importance of the input of geographic and local environmental factors on richness and composition of epigaeic steppe beetles (Coleoptera: Carabidae and Tenebrionidae) along a geographic (longitudinal/precipitation) gradient in the Inner Mongolia grassland. Specifically, we evaluate the associations of environmental variables representing climate and environmental heterogeneity with beetle assemblages. Beetles were sampled using pitfall traps at 25 sites scattered across the full geographic extent of the study biome in 2011-2012. We used variance partitioning techniques and multi-model selection based on the Akaike information criterion to assess the relative importance of the spatial and environmental variables on beetle assemblages. Species richness and abundance showed unimodal patterns along the geographic gradient. Together with space, climate variables associated with precipitation, water-energy balance and harshness of climate had strong explanatory power in richness pattern. Abundance pattern showed strongest association with variation in temperature and environmental heterogeneity. Climatic factors associated with temperature and precipitation variables and the interaction between climate with space were able to explain a substantial amount of variation in community structure. In addition, the turnover of species increased significantly as geographic distances increased. We confirmed that spatial and local environmental factors worked together to shape epigaeic beetle communities along the geographic gradient in the Inner Mongolia grassland. Moreover, the climate features, especially precipitation, water-energy balance and temperature, and the interaction between climate with space and environmental heterogeneity appeared to play important roles on controlling richness and abundance, and species compositions of epigaeic beetles.

Short-Term Responses of Ground-Dwelling Beetles to Ice Storm-Induced Treefall Gaps in a Subtropical Broad-Leaved Forest in Southeastern China.

Periodic natural disturbances shape the mosaic character of many landscapes and influence the distribution and abundance of organisms. In this study, we tested the effect of ice storm-induced treefall gaps on ground-dwelling beetle assemblages in different-aged successional stands of subtropical broad-leaved forest in southeastern China. We evaluated the relative importance of gap-phase microhabitat type (within gap, gap edge, and interior shaded) within different stand ages (regenerating stands and mature stands) as determinants of changes in beetle diversity and community structure. At 18 replicate sites sampled during 2009-2010, no significant differences were found in species richness and the abundances of the most common beetle species captured in pitfall traps among the three gap-phase microhabitat types, but the abundances of total beetles, as well as fungivorous and phytophagous species groups, were significantly lower in gap microhabitats than in interior shaded microhabitats in mature stands. Beetle assemblage composition showed no significant differences among the three microhabitat types, and only the fauna of gap plots slightly diverged from those of edge and shaded plots in mature stands. Cover of shrubs and stand age significantly affected beetle assemblage structure. Our results suggest that beetle responses to gap-phase dynamics in early successional forests are generally weak, and that effects are more discernible in the mature stands, perhaps due to the abundance responses of forest-specialist species.

Composition and distribution of ground-dwelling beetles among oak fragments and surrounding pine plantations in a temperate forest of North China.

In this study, we compared ground-dwelling beetle assemblages (Coleoptera) from a range of different oak fragments and surrounding conifer plantations to evaluate effects of forest size and surrounding matrix habitat in a temperate forest of north China. During 2000, beetles were sampled via pitfall traps within two large oak fragments (ca. 2.0-4.0 ha), two small oak fragments (ca. 0.2-0.4 ha) and two surrounding matrices dominated by pine plantations (>4 ha) in two sites of different aspects. Overall, no significantly negative effects from forest patch size and the surrounding matrix habitat were detected in total species number and abundance of ground-dwelling beetles. However, compared with small oak patches or pine plantations, more species were associated with an affinity for at least one large oak patch of the two aspects. Multivariate regression trees showed that the habitat type better determined the beetle assemblage structure than patch size and aspect, indicating a strong impact of the surrounding matrix. Linear mixed models indicated that species richness and abundance of all ground-dwelling beetles or beetle families showed different responses to the selected environmental variables. Our results suggest that more disturbed sites are significantly poorer in oak forest specialists, which are usually more abundant in large oak fragments and decrease in abundance or disappear in small fragments and surrounding matrix habitats. Thus, it is necessary to preserve a minimum size of forest patch to create conditions characteristic for forest interior, rather than the more difficult task of increasing habitat connectivity.

Elevational gradient in species richness pattern of epigaeic beetles and underlying mechanisms at east slope of Balang Mountain in southwestern China.

We report on the species richness patterns of epigaeic beetles (Coleoptera: Carabidae and Staphylinidae) along a subtropical elevational gradient of Balang Mountain, southwestern China. We tested the roles of environmental factors (e.g. temperature, area and litter cover) and direct biotic interactions (e.g. foods and antagonists) that shape elevational diversity gradients. Beetles were sampled at 19 sites using pitfall traps along the studied elevational gradient ranging from 1500 m-4000 m during the 2004 growing season. A total of 74416 specimens representing 260 species were recorded. Species richness of epigaeic beetles and two families showed unimodal patterns along the elevational gradient, peaking at mid-elevations (c. 2535 m), and the ranges of most beetle species were narrow along the gradient. The potential correlates of both species richness and environmental variables were examined using linear and second order polynomial regressions. The results showed that temperature, area and litter cover had strong explanatory power of beetle species richness for nearly all richness patterns, of beetles as a whole and of Carabidae and Staphylinidae, but the density of antagonists was associated with species richness of Carabidae only. Multiple regression analyses suggested that the three environmental factors combined contributed most to richness patterns for most taxa. The results suggest that environmental factors associated with temperature, area and habitat heterogeneity could account for most variation in richness pattern of epigaeic beetles. Additionally, the mid-elevation peaks and the small range size of most species indicate that conservation efforts should give attention to the entire gradient rather than just mid-elevations.

Effects of reforestation practices on Staphylinid beetles (Coleoptera: Staphylinidae) in Southwestern China forests.

In 2004, Staphylinid beetle (Coleoptera) assemblages were studied via pitfall trapping to examine the effects of reforestation in southwestern China forests. Sites included two 100-yr-old mature forest types (hemlock-spruce forest and birch forest), and three 40-yr-old forest types established after harvesting (spruce plantation, larch plantation, and natural broad-leaved forest). Staphylinid species richness was greater in natural broad-leaved forests than those in hemlock-spruce forests and spruce plantations, but no significant difference was found in abundance among the five forest types. Beetle assemblages from young forest stands were significantly different from those in older forest stands, and some environmental characteristics, i.e., elevation, proportion of broad-leaved trees, and coarse woody debris, significantly affected species abundances. Moreover, some staphylinid species predominantly found only in older forest stands indicate that mature forest specialists might be threatened by loss of habitat. So it is necessary to retain adequate patches of older successional stages for conserving these beetle assemblages.

[Species diversity of ground-dwelling beetles on northern slope of Daba Mountain, China].

By using pitfall trapping, the species composition and quantitative distribution of ground-dwelling beetles in man-made plantations in forest farm (MPFF), secondary natural forests in farmland (SFF), and man-made plantations in farmland (MPF) on northern slope of Daba Mountain were analyzed, and detrended correspondence analysis and cluster analysis were adopted to study the similarity of the species composition and quantitative distribution of the beetles among the three forest types. 1094 individuals of ground-dwelling beetles were captured in August 9-13th, 2002. Of these beetles, Staphylinidae and Chrysomelidae accounted for 40.59% and 33.18% of the total, respectively, and Carabidae, Leiodidae, Scarabaeidae, Curculionidae, Ptiliidae, and Pselaphidae each took more than 1% of the total. These eight families were considered as the common-occurring groups in the study area. The individuals of ground-dwelling beetles decreased from MPFF to SFF to MPF, and the family richness was obviously lower in MPF than in MPFF and SFF. The family composition and abundance of the beetles were significantly different between MPFF and SFF, but partial similarity was observed between MPF and other two forest types.

Distribution of carabid beetles (Coleoptera: Carabidae) across ecotones between regenerating and mature forests in southwestern China.

Edge effects resulting from logging on the distribution of carabid beetles (Coleoptera: Carabidae) were studied across ecotones between regenerating and mature forests established after harvesting of old-growth forests 20 yr prior to this study in southwestern China. Using pitfall traps, beetles were collected along five ecotone transects using nine samples with a distance interval of 25 m each. Although no significant differences were found in species richness and abundance of carabids among all three habitats, i.e., mature forest, young regenerating stand, and edge habitat, rarefaction estimates of species richness indicated that traps in young regenerating stands accumulated species faster than those on mature forest interiors and forest edges. Carabid species composition of the forest edges was more similar to those of the mature forest interiors than to those of the young regenerating stands. Variability in species composition was significantly reduced in young stands, suggesting that the carabid community from young stands is more homogeneous than the one from mature forests. Although most species occurred in all habitats, some species were significantly more abundant in mature forests and/or edges than in young stands. Results indicated that edge effects on forest carabids may persist for at least 20 yr after disturbance.

Cathepsin K regulates adipocyte differentiation: possible involvement of type I collagen degradation.

We previously found that cathepsin K (CTSK) played an important role in adipocyte differentiation. However, the underlying molecular mechanism is not clear. Through the time window study, it was observed that CTSK activities were required mainly in the early phases of adipogenic process. At the same time, the expression of type I collagen disappeared. However, type I collagen can still be observed during the whole process when the CTSK inhibitor-E64 was added. The mRNA levels of peroxisome proliferator-activated receptor gamma (PPAR-gamma) and CCAAT/enhancer binding protein alpha (C/EBP-alpha) was also declining. These imply that CTSK may play a role in adipogenesis in early differentiation phases and produce an effect at least partly by degrading type I collagen, which may provides a basis for developing novel therapeutic approaches to treat obesity and the diseases associated with it.

[The metabolic characteristics of isolated impaired fasting glucose and fasting hyperglycemia].

OBJECTIVE: To evaluate the metabolic characteristics of insulin secretion and insulin sensitivity in isolated impaired fasting glucose (iIFG) and isolated fasting hyperglycemia (IFH) and to clarify the factors responsible for the development of IFH. METHODS: Receiver operating characteristic curve (ROC) analysis was conducted in 1852 subjects. Three groups were classified according to a 75 g oral glucose tolerance test (OGTT): (1) normal glucose tolerance (NGT), n = 557; (2) iIFG, n = 221; (3) IFH, n = 81. The three groups were compared with insulin secretion (insulinogenic index) and insulin sensitivity (insulin sensitivity index). RESULTS: Using ROC analysis, the optimal cut point of fasting plasma glucose (FPG) related to diabetes diagnosis with OGTT was 6.695 mmol/L and the optimal cut point of FPG related to impaired glucose to lerance (IGT) diagnosis with OGTT was 5.590 mmol/L. From NGT to iIFG and IFH in these subjects, the insulinogenic index and insulin sensitivity index showed gradual decrease. CONCLUSION: Subjects with iIFG and IFH exhibit distinctly impaired early-phase insulin secretion and insulin sensitivity, indicating that both reduced insulin secretion and insulin resistance are the determinants of deterioration from NGT to iIFG and IFH.

Troglitazone acutely activates AMP-activated protein kinase and inhibits insulin secretion from beta cells.

Changes in AMP-activated protein kinase (AMPK) activity contribute to the regulation of insulin secretion. Troglitazone has been shown to lower serum insulin levels and protect beta cell function. The aim of the present study was to examine the effects of troglitazone on AMPK activity and insulin secretion in beta cells. Isolated rat islets and MIN6 cells were treated for a short (1 h) or a long time (20 h) with troglitazone. One-hour troglitazone treatment activated AMPK and inhibited both glucose-stimulated insulin secretion (GSIS) and the response of insulin secretion to combined stimuli of glucose and palmitate. Long (20 h) treatment with troglitazone caused a sustained phosphorylation of AMPK and acetyl-CoA carboxylase, and increased GSIS after withdrawal of the drug. This study provided evidence that troglitazone activated AMPK in beta cells. In addition to the insulin-sensitizing effects in peripheral tissues, troglitazone also directly inhibits insulin hypersecretion by the elevated glucose and fatty acids, and thus protects beta cells from glucolipotoxicity.