In situ transmission electron microscopy imaging of grain growth in a platinum nanobridge induced by electric current annealing

We report an in situ transmission electron microscopy (TEM) imaging of grain growth in a Pt nanobridge induced by a high electric current density. The change in morphology at the nanoscale was recorded in real time together with the electrical characterization of the Pt nanobridge. We find a drop in the differential resistance as the voltage across the bridge is increased; TEM inspection shows that this coincides with thermally induced grain growth, indicating that a reduction of grain boundary scattering is the cause of the resistance decrease.

Prevention and treatment of diabetes with resveratrol in a non-obese mouse model of type 1 diabetes

AIMS/HYPOTHESIS

We recently found that activation of the type III histone deacetylase sirtuin 1 suppresses T cell immune responses. Here we sought to determine the therapeutic potential of the sirtuin 1 activator resveratrol in the treatment of diabetes in the NOD mouse model of type 1 diabetes and the mechanisms underlying such potential.

METHODS

NOD mice were fed or subcutaneously injected with resveratrol and evaluated for development of diabetes. Splenocytes from resveratrol-treated and control mice were analysed by gene array. The altered expression of inflammatory genes induced by resveratrol was validated and the role of changed gene expression in prevention of diabetes was determined.

RESULTS

Resveratrol administration potently prevented and treated type 1 diabetes in NOD mice. Gene array analysis indicated a dramatic decrease in expression of Ccr6, which encodes chemokine (C-C motif) receptor (CCR) 6, in the splenocytes from resveratrol-treated mice. CCR6 abundance on IL-17-producing cells and CD11b(+)F4/80(hi) macrophages was inhibited by resveratrol treatment. Interestingly, CCR6(+) IL-17-producing cells and CD11b(+)F4/80(hi) macrophages accumulated in the spleens and pancreatic lymph nodes, but their presence in the pancreas was reduced, suggesting that resveratrol blocks their migration from peripheral lymphoid organs to the pancreas. Indeed, the migration of splenocytes toward media containing chemokine (C-C motif) ligand 20 (CCL20) was impaired by resveratrol treatment. CCL20 peptides, which block CCR6 binding to CCL20, inhibited development of type 1 diabetes.

CONCLUSIONS/INTERPRETATION

Inhibition of CCR6-mediated migration of inflammatory cells by resveratrol may provide a powerful approach for treatment of type 1 diabetes and possibly of other inflammatory diseases.

Metformin in prostate cancer: two for the price of one

BACKGROUND

Androgen deprivation therapy (ADT) for prostate cancer treatment induces a metabolic syndrome, which may contribute to non-cancer-related morbidity and mortality. Metformin may abrogate these effects. Additionally, metformin has potential antineoplastic activity in various malignancies including prostate cancer.

MATERIALS AND METHODS

A literature review using PubMed with the keywords: AMPK, androgen deprivation therapy, insulin resistance, metabolic syndrome, metformin and prostate cancer was undertaken.

RESULTS

This overview will look at the current evidence linking ADT and metabolic syndrome while discussing ongoing clinical trials under way assessing the effectiveness of metformin in abrogating these effects. The potential antineoplastic activity of metformin, mediated by multiple proposed mechanisms based on evidence from preclinical and clinical studies, will also be elucidated in this review.

CONCLUSIONS

Overall available data support the potential dual benefit of metformin on ADT-induced metabolic syndrome and in its antineoplastic activity in prostate cancer, justifying the need for ongoing clinical trials to confirm these effects as the evidence currently available for standard practice is lacking.

HB-EGF release mediates glucose-induced activation of the epidermal growth factor receptor in mesangial cells

Glomerular matrix accumulation is a hallmark of diabetic nephropathy. We showed that transactivation of the epidermal growth factor receptor (EGFR) is an important mediator of matrix upregulation in mesangial cells (MC) in response to high glucose (HG). Here, we study the mechanism of EGFR transactivation. In primary MC, EGFR transactivation by 1 h of HG (30 mM) was unaffected by inhibitors of protein kinase C, reactive oxygen species, or the angiotensin II AT1 receptor. However, general metalloprotease inhibition, as well as specific inhibitors of heparin-binding EGF-like growth factor (HB-EGF), prevented both EGFR and downstream Akt activation. HB-EGF was released into the medium by 30 min of HG, and this depended on metalloprotease activity. One of the metalloproteases shown to cleave proHB-EGF is ADAM17 (TACE). HG, but not an osmotic control, activated ADAM17, and its inhibition prevented EGFR and Akt activation and HB-EGF release into the medium. siRNA to either ADAM17 or HB-EGF prevented HG-induced EGFR transactivation. We previously showed that EGFR/Akt signaling increases transforming growth factor (TGF)-β1 transcription through the transcription factor activator protein (AP)-1. HG-induced AP-1 activation, as assessed by EMSA, was abrogated by inhibitors of metalloproteases, HB-EGF and ADAM17. HB-EGF and ADAM17 siRNA also prevented AP-1 activation. Finally, these inhibitors and siRNA prevented TGF-β1 upregulation by HG. Thus, HG-induced EGFR transactivation in MC is mediated by the release of HB-EGF, which requires activity of the metalloprotease ADAM17. The mechanism of ADAM17 activation awaits identification. Targeting upstream mediators of EGFR transactivation including HB-EGF or ADAM17 provides novel therapeutic targets for the treatment of diabetic nephropathy.

Hierarchically structured carbon-based composites: Design, synthesis and their application in electrochemical capacitors

This feature article provides an overview of the recent research progress on the hierarchically structured carbon-based composites for electrochemical capacitors. The basic principles of electrochemical capacitors, and the design, construction and performance of hierarchically structured carbon-based composites electrode materials with good ions and electron transportation and large specific surface area are discussed. The trend of future development of high-power and large-energy electrochemical capacitors is proposed.

Directional differentiation of chicken primordial germ cells into adipocytes, neuron-like cells, and osteoblasts

Primordial germ cells (PGCs) are useful for producing transgenic chickens and preserving genetic material in avian species. In this study, we investigated the in vitro differentiation potential of chicken PGCs into different cell types. For differentiation into adipocytes, chicken PGCs were cultured for 21 days in induction media containing dexamethasone, insulin and/or 3-isobutyl-1-methylxanthine (IBMX), and differentiation rates ranging from 74% to 91% were identified by oil red-O and alkaline phosphatase (ALP) staining. For differentiation into neuron-like cells, chicken PGCs were cultured for 3 or 7 days in the induction media containing retinoic acid (RA) and IBMX, and differentiation rates ranging from 71% to 87% were identified by toluidine blue staining and immunohistochemical staining. For differentiation into osteoblasts, chicken PGCs were cultured for 15 or 21 days in the induction media containing desamethasone, beta-glycerol phosphate and/or vitamin C, and differentiation rates ranging from 47% to 79% were confirmed by Von Kossa, cytochemical and immunohistochemical staining. These data suggest that, like mammalian PGCs, chicken PGCs can differentiate into different cell types in vitro.

Spatial and temporal expression of spermadhesin genes in reproductive tracts of male and female pigs and ejaculated sperm

Spermadhesins, a novel protein family identified in the reproductive tract of ungulates, have important roles in reproduction. In this study, the expression of pig (Sus domesticus) spermadhesion genes in seminal vesicles, prostate, and bulbourethral glands from birth to sexual maturity and the spatial expression in adult male and female genital tracts and ejaculated sperm of Meishan pigs were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). In general, all spermadhesin genes increased from Days 1 to 150 in the seminal vesicle and bulbourethral gland. However, their expression in the prostate was variable; it increased from Days 1 to 60 and then declined until Day 150. In adult boars, all genes had a very high level of expression in the seminal vesicle and somewhat lower (but still relatively high) in the prostate, caput and caudal epididymides, and bulbourethral gland. Expression of AQN1 and AQN3 was not detectable in the corpus epididymis. In the testis, AQN3 gene expression was not detectable, and gene expressions were weak for AQN1, PSP-I, and PSP-II, but strong for AWN. In female pigs, most spermadhesins had low expression in the cervix, uterine horn, oviduct, and ovary. Expression of AQN1 and AQN3 was very weak in the cervix and uterine horn. Signals for AQN1 in oviduct and ovary and AQN3 in ovary were not detectable, whereas AWN had high expression in the cervix and uterine horn. In ejaculated sperm, a strong mRNA signal of spermadhesins was detected. We concluded that transcripts of spermadhesins were not only distributed extensively in male and female reproductive tissues but also in ejaculated sperm. Furthermore, their dynamic changes of expression paralleled reproductive development. Seminal vesicles were the main source of spermadhesins; when the boar reached puberty, expression of spermadhesins reached very high levels.

Three-terminal electric transport measurements on gold nano-particles combined with ex situ TEM inspection

We have fabricated nanometer-spaced electrodes on electron-transparent silicon nitride membranes. A thin Cr/Au layer is evaporated on the backside of the membrane which serves as a gate electrode. Using these devices, we have performed three-terminal electron transport measurements on gold nano-particles at liquid helium temperature. Coulomb Blockade features have been observed and the capacitance to the gate has been extracted. After transport measurements, the Cr/Au back gate is removed and the devices are inspected with a transmission-electron microscope (TEM). TEM inspection reveals the presence of a few nano-particles in the nanogap, which is in agreement with the transport measurements. In addition, the nano-particle size as observed by TEM coincides with the one estimated from the gate capacitance value.

EGFR-PLCgamma1 signaling mediates high glucose-induced PKCbeta1-Akt activation and collagen I upregulation in mesangial cells

Glomerular matrix accumulation is a hallmark of diabetic nephropathy. We have recently shown that epidermal growth factor receptor (EGFR) transactivation mediates high glucose (HG)-induced collagen I upregulation through PI3K-PKCbeta1-Akt signaling in mesangial cells (MC). Phospholipase Cgamma1 (PLCgamma1) interacts with activated growth factor receptors and activates classic PKC isoforms. We thus studied its role in HG-induced collagen I upregulation in MC. Primary rat MC were treated with HG (30 mM) or mannitol as osmotic control. Protein kinase activation was assessed by Western blotting and collagen I upregulation by Northern blotting. Diabetes was induced in rats by streptozotocin. HG treatment for 1 h led to PLCgamma1 membrane translocation and Y783 phosphorylation, both indicative of its activation. Mannitol was without effect. PLCgamma1 Y783 phosphorylation was also seen in cortex and glomeruli of diabetic rats. HG induced a physical association between EGFR and PLCgamma1 as identified by coimmunoprecipitation. PLCgamma1 activation required EGFR kinase activity since it was prevented by the EGFR inhibitor AG1478 or overexpression of kinase-inactive EGFR (K721A). Phosphoinositide-3-OH kinase inhibition also prevented PLCgamma1 activation. HG-induced Akt S473 phosphorylation, effected by PKCbeta1, was inhibited by the PLCgamma inhibitor U73122. PLCgamma1 inhibition or downregulation by small interference RNA also prevented HG-induced collagen I upregulation. Our results indicate that EGFR-PLCgamma1 signaling mediates HG-induced PKCbeta1-Akt activation and subsequent collagen I upregulation in MC. Inhibition of EGFR or PLCgamma1 may provide attractive therapeutic targets for the treatment of diabetic nephropathy.

A study for maternal thyroid hormone deficiency during the first half of pregnancy in China

BACKGROUND

Maternal thyroid hormone deficiency is the most common disorder of thyroid function during pregnancy and can influence the outcome for mother and foetus. The purpose of this study was to investigate the prevalence of thyroid hormone deficiency during the first half of pregnancy in iodine sufficient areas of China.

MATERIALS AND METHODS

Four thousand eight hundred pregnant women from 10 hospitals during the first 20 weeks of gestation were enrolled in this study. All sera obtained from pregnant women were measured for thyrotropin, free thyroxine and thyroid peroxidase antibody. Screening for thyroid hormone deficiency was performed on pregnant women using gestational age-specific reference intervals or non-pregnant population reference intervals.

RESULTS

With gestational age-specific reference intervals as the criterion, the prevalence of subclinical hypothyroidism at 4, 8, 12,16 and 20 weeks of gestation was 4.59%, 6.15%, 4.68%, 4.53% and 5.96%, respectively, and the prevalence of hypothyroxinaemia was 3.69%, 1.11%, 2.92%, 1.29% and 2.29%, respectively. Different prevalence was obtained when non-pregnant population reference intervals was used as the criterion. If non-pregnant population reference intervals were used, the percentage of potentially misclassified cases of subclinical hypothyroidism were 0.18%, 2.85%, 4.1%, 3.24%, and 3.21%, respectively, and 3.45%, 0.66%, 2.34%, 1.29%, and 1.83%, respectively, in potentially misclassified cases of hypothyroxinaemia.

CONCLUSIONS

The percentage of potentially misclassified cases of subclinical hypothyroidism and hypothyroxinaemia in pregnant women decreased by using the gestational age-specific reference intervals as a diagnostic criteria during the first half of pregnancy.

Apoptosis-inducing effect of cinobufacini, Bufo bufo gargarizans Cantor skin extract, on human hepatoma cell line BEL-7402

Cinobufacini, a water-soluble preparation of Chinese medicine, is extracted from the skin of Bufo bufo gargarizans Cantor. The present study sought to investigate the effects of Cinobufacini on apoptosis of the hepatocellular carcinoma cell line BEL-7402. Cell viability was measured by methyl thiazolyl tetrazolium assay. Cell morphology was observed by Hoechst 33258 staining. Western blotting analysis was used to detect Bax and Bcl-2 expression. Results indicated that Cinobufacini inhibited the proliferation of BEL-7402 cells in a dose and time-dependent manner. Marked morphological changes indicative of apoptosis were observed after treatment with different concentrations of Cinobufacini. Western blot analysis showed that Bcl-2 expression was down-regulated while Bax expression was upregulated. Thus, Cinobufacini may have a significant　apoptosis-inducing effect on BEL-7402 cells, and this could prove useful for further anti-cancer research.

Differential potency of drosomycin to Neurospora crassa and its mutant: implications for evolutionary relationship between defensins from insects and plants

Drosomycin, the first inducible antifungal peptide isolated from Drosophila, belongs to the superfamily of CSalphabeta-type defensins. In the present study we report a modified approach for high-level expression of drosomycin, which allows us to evaluate its differential potency on the filamentous fungus Neurospora crassa WT (wild type) and N. crassa MUT16, a specific resistance mutant strain to plant defensins, by using different approaches. The results presented here show for the first time that N. crassa MUT16 is resistant to our recombinant drosomycin. Differential survival rates of Drosophila larvae infected by N. crassa WT and MUT16 further confirm the key antifungal role of drosomycin in vivo. The absence of activity against MUT16 suggests a mechanical commonality between drosomycin and plant defensins, which provides additional evidence in favor of their homologous relationship. Furthermore, the existence of drosomycin-like molecules in fungi suggests that all these peptides could originate from a common ancestry rather than horizontal gene transfer between plants and insects, which is further strengthened by the monophyletic origin of these peptides from plants, fungi and insects.

Assessment of wall shear stress in the common carotid artery of healthy subjects using 3.0-tesla magnetic resonance

BACKGROUND

Wall shear stress (WSS) has been proven to play a critical role in the formation and development of atherosclerotic plaques. Measurement of WSS in vivo is significant for the clinical assessment of atherosclerosis.

PURPOSE

To assess the magnitude and distribution of local WSS in the common carotid artery (CCA) in vivo using 3.0T magnetic resonance (MR).

MATERIAL AND METHODS

The common carotid artery of eight healthy volunteers was studied using a cine phase-contrast MR sequence. A three-dimensional paraboloid model was applied to fit the velocity profiles, and the WSS values were calculated. The cross-sectional area, average flow velocity, maximum velocity, and flow rate were also obtained.

RESULTS

Mean WSS was 0.850 +/- 0.195 (range 0.132-3.464) N/m(2) for the common carotid arteries; the spatial and temporal distribution and change of WSS were displayed. During a cardiac cycle, the mean velocity was 22.8 +/- 3.5 (16.9-28.3) cm/s, blood flow rate 8.03+/-1.45 (5.73-10.72) ml/s, and luminal vessel area 34.94+/-7.06 (24.25-49.01) mm(2).

CONCLUSION

Local WSS values in CCAs can be measured using 3.0T MR imaging combined with image-processing techniques. Intersubject variations were found in the distribution and magnitude of wall shear stress as well as in the flow profile pattern in CCAs, which may be caused by different vessel morphologies.