Suppression effects of AICAR on insulin secretion involved in peroxisome proliferator-activated receptor gamma changes in INS-1 cells

BACKGROUND

AMP-activated protein kinase (AMPK) activation is known to attenuate glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells. However, the underlying mechanisms are poorly understood. The purpose of this study was to examine the effects of AMPK activation on insulin secretion and to determine whether peroxisome proliferator-activated receptors (PPAR) are involved in the effects on INS-1 cells.

METHODS

INS-1 cells, insulinoma cell lines, were treated with an activator (AICAR) or inhibitor (Compound C) of AMPK as well as inhibitors of PPAR [MK886 and biphenol A diglycidyl ether (BADGE)] for different treatment times.

RESULTS

AICAR-induced AMPK activation significantly attenuated GSIS as well as insulin content. Meanwhile, AMPK activation increased the mRNA levels of both PPARalpha and PPARgamma. However, with regard to DNA binding, AMPK activation upregulated PPARgamma only, and it was possible to reduce the increment with the AMPK inhibitor. Moreover, the AICAR-induced suppression of insulin secretion can be counteracted by the PPARgamma inhibitor, BADGE but not the PPARalpha inhibitor.

CONCLUSIONS

AICAR-induced glucose-stimulated insulin secretion reduction correlates mainly with PPARgamma changes.

The Effect of Stem Structure on Stress Distribution of a Custom-Made Hip Prosthesis

A custom-made hip is essential for the initial stability and longevity which correspond to an optimal stress distribution, since a standard hip cannot always satisfy every patient's need. In order to find out the designing principles of a custom-made hip, a patient's personal features on which the design was based were acquired. In this study, an integrated finite element model of the hip (including ilium, acetabular cup, femoral head, femoral stem, and femur) was created based on the computed tomography (CT) images of this patient. A series model with different stem length, cross-section, and collodiaphyseal angle were analysed under both static and quasi-static loading conditions. Comparing the stress distribution on each part of the hip prosthesis with that of the natural hip before replacement, the optimal stem structure for this patient was found. In addition, the changes of interspace between acetabular cup and femoral head were measured according to dynamic CT images on the healthy side of this patient during a gait cycle. Results correspond to the trail of the maximum contact stress sites, which were mainly located on the superolateral surface of the acetabular cup. This custom-design method can also be adopted for other patients.

Quantum transport in alkane molecular wires: effects of binding modes and anchoring groups

Effects of binding modes and anchoring groups on nonequilibrium electronic transport properties of alkane molecular wires are investigated from atomic first-principles based on density functional theory and nonequilibrium Green's function formalism. Four typical binding modes, top, bridge, hcp-hollow, and fcc-hollow, are considered at one of the two contacts. For wires with three different anchoring groups, dithiol, diamine, or dicarboxylic acid, the low bias conductances resulting from the four binding modes are all found to have either a high or a low value, well consistent with recent experimental observations. The trend can be rationalized by the behavior of electrode-induced gap states at small bias. When bias increases to higher values, states from the anchoring groups enter into the bias window and contribute significantly to the tunneling process so that transport properties become more complicated for the four binding modes. Other low bias behaviors including the values of the inverse length scale for tunneling characteristic, contact resistance, and the ratios of the high/low conductance values are also calculated and compared to experimental results. The conducting capabilities of the three anchoring groups are found to decrease from dithiol, diamine to dicarboxylic-acid, largely owing to a decrease in binding strength to the electrodes. Our results give a clear microscopic picture to the transport physics and provide reasonable qualitative explanations for the corresponding experimental data.

Efficacy and safety of monotherapy of sitagliptin compared with metformin in patients with type 2 diabetes

AIM

To compare the efficacy and safety of monotherapy with sitagliptin and metformin in treatment-naïve patients with type 2 diabetes.

METHODS

In a double-blind study, 1050 treatment-naïve patients (i.e. not taking an antihyperglycaemic agent for > or =16 weeks prior to study entry) with type 2 diabetes and an HbA(1c) 6.5-9% were randomized (1:1) to treatment with once-daily sitagliptin 100 mg (N = 528) or twice-daily metformin 1000 mg (N = 522) for 24 weeks. Metformin was up-titrated from 500 to 2000 mg per day (or maximum tolerated daily dose > or =1000 mg) over a period of 5 weeks. The primary analysis used a per-protocol (PP) approach to assess whether sitagliptin was non-inferior to metformin based on HbA(1c) change from baseline at week 24. Non-inferiority was to be declared if the upper boundary of the 95% confidence interval (CI) for the between-group difference in this endpoint was <0.40%.

RESULTS

From a mean baseline HbA(1c) of 7.2% in the PP population, HbA(1c) change from baseline was -0.43% with sitagliptin (n = 455) and -0.57% with metformin (n = 439). The between-group difference (95% CI) was 0.14% (0.06, 0.21), thus confirming non-inferiority. Baseline HbA(1c) influenced treatment response, with larger reductions in HbA(1c) observed in patients with baseline HbA(1c)> or =8% in the sitagliptin (-1.13%; n = 74) and metformin (-1.24%; n = 73) groups. The proportions of patients at week 24 with HbA(1c) values at the goals of <7 or <6.5% were 69 and 34% with sitagliptin and 76 and 39% with metformin, respectively. Fasting plasma glucose changes from baseline were -11.5 mg/dL (-0.6 mmol/l) and -19.4 mg/dl (-1.1 mmol/l) with sitagliptin and metformin, respectively (difference in LS mean change from baseline [95% CI] = 8.0 mg /dl [4.5,11.4]). Both treatments led to similar improvements from baseline in measures of homeostasis model assessment-beta cell function (HOMA-beta) and insulin resistance (HOMA-IR). The incidence of hypoglycaemia was 1.7% with sitagliptin and 3.3% with metformin (p = 0.116). The incidence of gastrointestinal-related adverse experiences was substantially lower with sitagliptin (11.6%) compared with metformin (20.7%) (difference in incidence [95% CI] = -9.1% [-13.6,-4.7]), primarily because of significantly decreased incidences of diarrhoea (3.6 vs. 10.9%; p < 0.001) and nausea (1.1 vs. 3.1%; p = 0.032). Body weight was reduced from baseline with both sitagliptin (LS mean change [95% CI] = -0.6 kg [-0.9,-0.4]) and metformin (-1.9 kg [-2.2, -1.7]) (p < 0.001 for sitagliptin vs. metformin).

CONCLUSIONS

In this 24-week monotherapy study, sitagliptin was non-inferior to metformin in improving HbA(1c) in treatment-naïve patients with type 2 diabetes. Although both treatments were generally well tolerated, a lower incidence of gastrointestinal-related adverse experiences was observed with sitagliptin.

Effect of the ratios of diameter of silo to bead on the pressure screening in granular columns

We present the apparent mass measurements at the bottom of granular packings for different bead and silo sizes. The redirection parameter K in Janssen theory is found to increase with the ratios of the diameter of the silo to the bead. We attribute this feature to the friction between the beads and the confining wall of silo; it is the role of friction that leads to variations in the shielding of vertical stresses as well as pressure screening.

O+OH-->O(2)+H: A key reaction for interstellar chemistry. New theoretical results and comparison with experiment

We report extensive, fully quantum, time-independent (TID) calculations of cross sections at low collision energies and rate constants at low temperatures for the O+OH reaction, of key importance in the production of molecular oxygen in cold, dark, interstellar clouds and in the chemistry of the Earth's atmosphere. Our calculations are compared with TID calculations within the J-shifting approximation, with wave-packet calculations, and with quasiclassical trajectory calculations. The fully quantum TID calculations yield rate constants higher than those from the more approximate methods and are qualitatively consistent with a low-temperature extrapolation of earlier experimental values but not with the most recent experiments at the lowest temperatures.

Hemoglobin Hakkari: an autosomal dominant form of beta thalassemia with inclusion bodies arising from de novo mutation in exon 2 of beta globin gene

Certain beta globin gene mutations produce a thalassemia major phenotype in the heterozygous state. While most such patients have thalassemia intermedia, we describe a young Guatemalan child with a de novo mutation in the beta globin gene, codon 31 T --> G (Hemoglobin Hakkari), who developed severe anemia at the age of 10 months and remains transfusion-dependent. The substitution of B13 leucine with arginine in the beta globin results in alteration of a critical heme contact point resulting in an extremely unstable variant hemoglobin and a clinical picture that is characterized by ineffective erythropoiesis and numerous intracytoplasmic inclusions within the erythrocyte precursors of the bone marrow. .

Low-pressure membrane integrity tests for drinking water treatment: A review

Low-pressure membrane systems, including microfiltration (MF) and ultrafiltration (UF) membranes, are being increasingly used in drinking water treatments due to their high level of pathogen removal. However, the pathogen will pass through the membrane and contaminate the product if the membrane integrity is compromised. Therefore, an effective on-line integrity monitoring method for MF and UF membrane systems is essential to guarantee the regulatory requirements for pathogen removal. A lot of works on low-pressure membrane integrity tests have been conducted by many researchers. This paper provides a literature review about different low-pressure membrane integrity monitoring methods for the drinking water treatment, including direct methods (pressure-based tests, acoustic sensor test, liquid porosimetry, etc.) and indirect methods (particle counting, particle monitoring, turbidity monitoring, surrogate challenge tests). Additionally, some information about the operation of membrane integrity tests is presented here. It can be realized from this review that it remains urgent to develop an alternative on-line detection technique for a quick, accurate, simple, continuous and relatively inexpensive evaluation of low-pressure membrane integrity. To better satisfy regulatory requirements for drinking water treatments, the characteristic of this ideal membrane integrity test is proposed at the end of this paper.

Non-viral Smad7 gene delivery and attenuation of postoperative peritoneal adhesion in an experimental model

BACKGROUND

Postoperative intra-abdominal adhesion is associated with high morbidity and mortality. Smad7, a protein that occupies a strategic position in fibrogenesis, inhibits the transforming growth factor (TGF) beta/Smad signalling pathway. In this study the therapeutic potential of exogenous Smad7 in preventing fibrogenesis in postoperative intra-abdominal adhesion was investigated.

METHODS

Intra-abdominal adhesion was induced in a rodent model by peritoneal abrasion. Smad7 was delivered into the peritoneal cavity by a non-viral ultrasound-microbubble-mediated naked gene transfection system. The effect of Smad7 transgene on adhesion formation was studied by measuring changes in TGF-beta, fibrogenic factors, alpha-SMA and Smad2/3 activation in the anterior abdominal wall.

RESULTS

Four weeks after surgical abrasion, all rats developed significant peritoneal adhesion with enhanced TGF-beta expression, increased levels of extracellular matrix components and activated myofibroblasts, accompanied by decreased Smad7 expression and increased Smad2/3 activation. In rats treated with the Smad7 transgene, the incidence and severity of peritoneal adhesion were significantly reduced, with biochemical downregulation of fibrogenic factors and inhibition of Smad2/3 activation. Serial quantitation using magnetic resonance imaging revealed a significant reduction in adhesion areas from day 14 onwards.

CONCLUSION

Ultrasound-microbubble-mediated gene transfection provides timely targeted gene delivery for the treatment of postoperative peritoneal adhesions.

Lysophosphatidic acid-induced platelet shape change revealed through LPA(1-5) receptor-selective probes and albumin

Lysophosphatidic acid (LPA), a component of mildly-oxidized LDL and the lipid rich core of atherosclerotic plaques, elicits platelet activation. LPA is the ligand of G protein-coupled receptors (GPCR) of the EDG family (LPA(1-3)) and the newly identified LPA(4-7) subcluster. LPA(4), LPA(5) and LPA(7) increase cellular cAMP levels that would induce platelet inhibition rather than activation. In the present study we quantified the mRNA levels of the LPA(1-7) GPCR in human platelets and found a rank order LPA(4) = LPA(5) > LPA(7) > LPA(6) = LPA(2) >> LPA(1) > LPA(3). We examined platelet shape change using a panel of LPA receptor subtype-selective agonists and antagonists and compared them with their pharmacological profiles obtained in heterologous LPA(1-5) receptor expression systems. Responses to different natural acyl and alkyl species of LPA, and octyl phosphatidic acid analogs, alpha-substituted phosphonate analogs, N-palmitoyl-tyrosine phosphoric acid, N-palmitoyl-serine phosphoric acid were tested. All of these compounds elicited platelet activation and also inhibited LPA-induced platelet shape change after pre-incubation, suggesting that receptor desensitization is likely responsible for the inhibition of this response. Fatty acid free albumin (10 microM) lacking platelet activity completely inhibited platelet shape change induced by LPA with an IC(50) of 1.1 microM but had no effect on the activation of LPA(1,2,3,&5) expressed in endogenously non-LPA-responsive RH7777 cells. However, albumin reduced LPA(4) activation and shifted the dose-response curve to the right. LPA(5) transiently expressed in RH7777 cells showed preference to alkyl-LPA over acyl-LPA that is similar to that in platelets. LPA did not increase cAMP levels in platelets. In conclusion, our results with the pharmacological compounds and albumin demonstrate that LPA does not induce platelet shape change simply through activation of LPA(1-5), and the receptor(s) mediating LPA-induced platelet activation remains elusive.

Ecology-based screen identifies new metabolites from a Cordyceps-colonizing fungus as cancer cell proliferation inhibitors and apoptosis inducers

OBJECTIVES

This study aims to identify new anti-cancer agents from Cordyceps-colonizing fungi, using an ecology-based approach. It also aims to explore their anti-cell proliferative mechanisms, and to evaluate their anti-tumour effects in vivo.

MATERIALS AND METHODS

Extracts from Cordyceps-colonizing fungi were tested on HeLa cells, and active extracts were separated to obtain anti-tumour metabolites; their structures were elucidated by mass and nuclear magnetic resonance spectroscopy. Cell cycle analysis was evaluated using flow cytometry. Tumour formation assays were performed using C57BL/6J mice.

RESULTS

Based on ecological considerations, the selected extracts were subjected to initial anti-tumour screening. Bioassay-guided fractionation of the active extract afforded two new epipolythiodioxopiperazines, named gliocladicillins A (1) and B (2). (A) 1 and B (2) inhibited growth of HeLa, HepG2 and MCF-7 tumour cells. Further study demonstrated that both preparations arrested the cell cycle at G(2)/M phase in a dose-dependent manner, and induced apoptosis through up-regulation of expression of p53, p21, and cyclin B, and activation of caspases-8, -9 and -3. These data imply that gliocladicillins A (1) and B (2) induce tumour cell apoptosis through both extrinsic and intrinsic pathways. In addition, in vivo studies showed that they displayed significant inhibitory effects on cell population growth of melanoma B16 cells implanted into immunodeficient mice.

CONCLUSIONS

Gliocladicillins A (1) and B (2) are effective anti-tumour agents in vitro and in vivo and should be further evaluated for their potential in clinical use.

Formaldehyde and volatile organic compounds in Hong Kong homes: concentrations and impact factors

This paper presents formaldehyde and volatile organic compounds (VOC) concentrations, potential sources and impact factors in 100 homes. The 24-h average formaldehyde concentration in 37 homes exceeded the good class of the Hong Kong Indoor Air Quality Objectives (HKIAQO), whereas the total VOCs concentration in all homes was lower than the HKIAQO. Compared to other East Asian cities, indoor formaldehyde and styrene in Hong Kong was the highest, reflecting that the homes in Hong Kong were more affected by household products and materials. The formaldehyde concentration in newly built apartments was significantly higher than that in old buildings, whereas no relationship between the concentration and the building age was found for VOCs. There was no difference for formaldehyde and toluene between smoking and non-smoking homes, suggesting that cigarette smoking was not the major source of these two species. Homes of a couple with a child had higher formaldehyde and acetic acid concentrations, while homes with more than three people had higher concentrations of 1-butanol, heptane and d-limonene. When shoes were inside the homes, heptane, acetic acid, nonane and styrene concentrations were statistically higher than that when shoes were out of the homes. Furthermore, higher levels of 1,2,4-trimethylbenzene, styrene, nonane and heptane were found in gas-use families rather than in electricity-use homes.

PRACTICAL IMPLICATIONS

Long-term exposure to formaldehyde and volatile organic compounds (VOC) in indoor environments may cause a number of adverse health effects such as asthma, dizziness, respiratory and lung diseases, and even cancers. Therefore, it is critical to minimize indoor air pollution caused by formaldehyde and VOCs. The findings obtained in this study would significantly enhance our understanding on the levels, emission sources and factors which affect indoor concentrations of formaldehyde and VOCs. The results can help housing designers, builders, home residents, and housing department of the government to improve indoor air quality (IAQ) by means of appropriate building materials, clean household products and proper life styles. It can also help policy makers reconcile the IAQ objectives and guidelines.

Effect of metronomic use of zoledronic acid (ZOL) on antitumor and antiosteoclastic effects in breast cancer patients with bone metastasis

e14603

Background: Zoledronic acid (ZOL) can reduce the risk of skeletal-related events (SREs) and may have direct and indirect antitumor effects, which have been shown in animal models, pilot clinical studies as well as in recent phase III randomized trials. However, the pharmacokinetics of the drug in breast cancer patients remains to be elucidated and optimized. The purpose of this randomized study was to compare the effects of ZOL on osteoclasts and angiogenesis between a weekly low-dose versus a conventional dosage. Methods: Sixty breast cancer patients with bone metastases were recruited in this randomized phase II clinical study. The participants either received ZOL 1mg IV weekly for 4 doses or a single dose of ZOL 4mg IV. No other antitumor treatments were administered. During the first month after initial infusion of ZOL, serial blood samples were collected on day 1, 15 and 29 measuring markers for bone resorption (NTx), angiogenesis (VEGF), and tumor burden (CEA and CA15–3). Results: Compared to a single-dose administration, weekly low dose of ZOL resulted in a greater reduction in serum levels of VEGF and NTx, with a significant trend over time during one month observation. There were no statistically significant differences in circulating levels of CEA and CA15–3 between the two dosing regimens. Patients who received metronomic ZOL had a longer median time to disease progression (TTP) (7.0 months, 95%CI, 6.1–7.9 months) than those who had a single dose of ZOL (2.8 months, 95%CI, 0–5.7 months; p=0.076). Conclusions: The metronomic use of low-dose ZOL 1 mg appeared to be more effective than the conventional regimen in the long-lasting reduction of VEGF and NTx, and in prolonging TTP. This dosing schedule should be further assessed in phase III trials as we demonstrated that ZOL 1mg has greater antitumor properties in our study.

No significant financial relationships to disclose.

High-titer lentiviral vectors stimulate fetal calf serum-specific human CD4 T-cell responses: implications in human gene therapy

Human immunodeficiency virus-1-derived lentiviral vectors have been increasingly used for gene delivery in both pre-clinical and clinical models. Numerous studies have shown that dendritic cells (DC) transduced with concentrated lentiviral vectors can induce primary T-cell responses to viral and tumor antigens. In this study, we attempted to generate influenza hemagglutinin-specific CD4 T cells using lentiviral vectors containing the signal sequence and human lysosome-associated membrane protein to target hemagglutinin to the major histocompatibility complex class II processing pathway. Autologous dendritic cells were generated in serum-free medium and transduced with concentrated, high-titer lentiviruses to stimulate autologous T cells. Unexpectedly, we failed to generate influenza hemagglutinin-specific CD4 T cells rather than T cells specific for fetal calf serum (FCS). By limiting dilution, we established several FCS-specific CD4 T-cell clones restricted by human leukocyte antigen-DR1 and human leukocyte antigen-DR4. Lentiviruses produced in human serum-adapted 293 cells or in serum-free medium were unable to sensitize dendritic cells for recognition by FCS-specific CD4 T-cell clones. Our results indicate that residual FCS in concentrated lentiviral pellets is, in part, responsible for its immunogenicity. These FCS-specific CD4 T cells may be useful in testing clinical grade lentiviral vectors for the presence of contaminating FCS.

Pregnancy outcomes after kidney donation

The outcome of pregnancy in kidney donors has generally been viewed to be favorable. We determined fetal and maternal outcomes in a large cohort of kidney donors. A total of 2102 women have donated a kidney at our institution; 1589 donors responded to our pregnancy surveys; 1085 reported 3213 pregnancies and 504 reported none. Fetal and maternal outcomes in postdonation pregnancies were comparable to published rates in the general population. Postdonation (vs. predonation) pregnancies were associated with a lower likelihood of full-term deliveries (73.7% vs. 84.6%, p = 0.0004) and a higher likelihood of fetal loss (19.2% vs. 11.3%, p < 0.0001). Postdonation pregnancies were also associated with a higher risk of gestational diabetes (2.7% vs. 0.7%, p = 0.0001), gestational hypertension (5.7% vs. 0.6%, p < 0.0001), proteinuria (4.3% vs. 1.1%, p < 0.0001) and preeclampsia (5.5% vs. 0.8%, p < 0.0001). Women who had both pre- and post-donation pregnancies were also more likely to have these adverse maternal outcomes in their postdonation pregnancies. In this large survey of previous living donors in a single center, fetal and maternal outcomes and pregnancy outcomes after kidney donation were similar to those reported in the general population, but inferior to predonation pregnancy outcomes.

Impact of surface chemistry on grain boundary induced intrinsic stress evolution during polycrystalline thin film growth

First principles calculations were integrated with cohesive zone and growth chemistry models to demonstrate that adsorbed species can significantly alter stresses associated with grain boundary formation during polycrystalline film growth. Using diamond growth as an example, the results show that lower substrate temperatures increase the hydrogen content at the surface, which reduces tensile stress, widens the grain boundary separations, and permits additional atom insertions that can induce compressive stress. More generally, this work demonstrates that surface heteroatoms can lead to behavior which is not readily described by existing models of intrinsic stress evolution.