[Simultaneous determination of ethephon, thidiazuron, diuroN residues in cotton by using high performance liquid chromatography-tandem mass spectrometry]

A method for the determination of ethephon, thidiazuron and diuron in cotton samples has been developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with methanol-water. The separation was carried out on a C8 column (150 mm x 4.6 mm, 5 microm) with methanol-water (6:4, v/v) as mobile phase at a flow rate of 0.4 mL/min, and the injection volume was 20 microL. Then the sample solution was analyzed by HPLC-MS/MS in negative ion mode with multiple reaction monitoring (MRM). There were one precursor/two product ion transitions for each pesticide. The results showed that the working curves were linear in the range of 0-10 microg/L for ethephon and thidiazuron, and 0-1 microg/L for diuron. The correlation coefficients (r) were all over 0. 999. The limits of quantitation (LOQ) of ethephon, diuron were 40 microg/kg, that of thidiazuron was 4 microg/kg. The average recoveries varied from 89.4% to 100.2% with the relative standard deviations (RSDs) of 5.7%-11.5% at three spiked levels (LOQ, 2LOQ and 4LOQ). The method is simple, rapid and accurate, and can meet the requirements of the domestic and international legislation. The method adapts to confirm the residues of ethephon, thidiazuron and diuron pesticides in cotton samples.

Release of High Mobility Protein Box-1 is Greatly Regulated by Nuclear Factor of Activated T Cell-2 in Human Monocytes

Close talk between inflammatory mediators and immunological cytokines has been discovered and reported. In this study, the role of nuclear factor of activated T cell-2 (NFAT2) in regulation of high mobility group box-1 (HMGB1) release was investigated. THP-1 cell and HEK293T cell were incubated and stimulated by lipopolysaccharide (LPS). Firstly, binding site between HMGB1 and NFAT2 was identified by co-immunoprecipitation (IP). Box A, Box B and CT domain of HMGB1 were constructed, as well as Rel-homology-domain (RHD), pre-RHD and pro-RHD of NFAT2. THP-1 cell was harvested, cell lysate and culture medium were collected at appointed times. Binding between HMGB1 and NFAT2 was measured, HMGB1 protein level in culture medium was analyzed at the same time. Secondly, the role of NFAT2 in regulating HMGB1 release was investigated. When THP-1 cell was cultured for 24 h, HMGB1 protein level was measured at appointed times with or without siRNA to inhibit NFAT2 expression. Our data show that HMGB1 bound to NFAT2 in THP-1 cell cytoplasm. Further experiments showed that box B domain of HMGB1 could bind to pre-RHD of NFAT2. After stimulation by LPS, interaction between HMGB1 and NFAT2 was discovered decreasing gradually. However, HMGB1 protein level increased in culture medium at the same time. Furthermore, HMGB1 release could be enhanced by NFAT2 inhibition. Taken together, release of HMGB1 could be regulated by NFAT2 in human monocytes.

Crystal plane effects of nano-CeO2 on its antioxidant activity

Due to the conflicting reports on the antioxidant activity of cerium oxide nanoparticles, much work has been done to explore the factors influencing the antioxidant activity of nano-CeO₂.

Studies on the Effect of Pellet Size on Positive Conveying in Helically Grooved Single Screw Extruders

The helical grooved barrel feed section permits, when the barrel channel aspect ratio and the barrel channel helical angle are properly designed, an operating mode where the positive conveying is prevailing. While the pellet size of materials is varied, different dimension relationships of the barrel channel depth and pellet size could induce different equivalent barrel channel aspect ratios with the transformation of solids conveying mechanisms from the positive conveying to the friction-drag conveying. Considering the effect of dimension relationships on the solids conveying mechanism, a novel pellet-size physical model was established to guide the available design of the barrel channel geometry for positive conveying. In the pellet-size model, one or two shear interfaces were identified inside the solid-plug resulting in different equivalent barrel channel aspect ratios, based on which the solids conveying mechanism on the shear interfaces was detailed by the boundary condition equations for positive conveying. Besides, the theoretical simulations are also compared with the on-line measuring experimental data. The results show that the equivalent barrel channel aspect ratio on the shear interfaces exists indeed and determines the solids conveying mechanism, which is well confirmed by the excellent consistence between the predicted and measured data.

DAMGO in the central amygdala alleviates the affective dimension of pain in a rat model of inflammatory hyperalgesia

Pain has sensory-discriminative and emotional-affective dimensions. Recent studies show that the affective component can be assessed with a conditioned place avoidance (CPA) test. We hypothesized that systemic morphine before a post-conditioning test would more potently attenuate the affective aspect compared to the sensory component and that [d-Ala2-N-Me-Phe4, Gly-ol5]-enkephalin (DAMGO), a μ-selective opioid receptor agonist, injected into the central nucleus of the amygdala (CeA) would reduce established CPA. A rat model of inflammatory pain, produced by a complete Freund adjuvant (CFA) injection into the hind paw, was combined with a CPA test. Three experiments were performed on adult male Sprague-Dawley rats. Systemic morphine (0.5 or 1.0mg/kg) in Experiment 1, intrathecal (i.t.) morphine (2.5 μg/rat) in Experiment 2, and intra-CeA DAMGO (7.7-15.4 ng/0.4 μl) in Experiment 3 were given to CFA-injected rats (n=6-8/group) prior to a post-conditioning test. Saline-injected rats were used as control. Time spent in a pain-paired compartment was recorded twice, before conditioning and after a post-conditioning test. Paw withdrawal latency (PWL) to a noxious thermal stimulus was measured before experiment at day-1 and after the post-conditioning test; hyperalgesia was defined as a decrease in PWL. The data showed that CFA-injected rats had significantly negative CPA compared to those of saline-injected rats (P<0.05). Low-dosage systemic morphine significantly (P<0.05) reduced CFA-induced CPA but had no effect on PWL. I.t. morphine did not inhibit the display of CPA but significantly increased PWL, suppressing hyperalgesia (P<0.05). Intra-CeA DAMGO significantly inhibited the display of CPA compared to saline (P<0.05) but had no effect on PWL. The data demonstrate that morphine attenuates the affective component more powerfully than it does the sensory and suggests that the sensory and the emotional-affective dimensions are underpinned by different mechanisms.

The neuroprotective role and mechanisms of TERT in neurons with oxygen-glucose deprivation

Telomerase reverse transcriptase (TERT) is reported to protect neurons from apoptosis induced by various stresses including hypoxia-ischemia (HI). However, the mechanisms by which TERT exerts its anti-apoptotic role in neurons with HI injury remain unclear. In this study, we examined the protective role and explored the possible mechanisms of TERT in neurons with HI injury in vitro. Primary cultured neurons were exposed to oxygen and glucose deprivation (OGD) for 3h followed by reperfusion to mimic HI injury in vivo. Plasmids containing TERT antisense, sense nucleotides, or mock were transduced into neurons at 48h before OGD. Expression and distribution of TERT were measured by immunofluorescence labeling and western blot. The expression of cleaved caspase 3 (CC3), Bcl-2 and Bax were detected by western blot. Neuronal apoptosis was measured with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). The mitochondrial reactive oxygen species (ROS) were measured by MitoSOX Red staining. Fluorescent probe JC-1 was used to measure the mitochondrial membrane potential (ΔΨm). We found that TERT expression increased at 8h and peaked at 24h in neurons after OGD. CC3 expression and neuronal apoptosis were induced and peaked at 24h after OGD. TERT inhibition significantly increased CC3 expression and neuronal apoptosis after OGD treatment. Additionally, TERT inhibition decreased the expression ratio of Bcl-2/Bax, and enhanced ROS production and ΔΨm dissipation after OGD. These data suggest that TERT plays a neuroprotective role via anti-apoptosis in neurons after OGD. The underlying mechanisms may be associated with regulating Bcl-2/Bax expression ratio, attenuating ROS generation, and increasing mitochondrial membrane potential.

The safety of postoperative hormone replacement therapy in epithelial ovarian cancer patients in China

OBJECTIVE

This study sought to determine whether postoperative hormone replacement therapy (HRT) has a negative influence on the progression-free and overall survival of epithelial ovarian carcinoma patients.

METHODS

A retrospective chart review identified 77 patients with invasive epithelial ovarian cancer who had received HRT after primary surgical treatment from January 1995 to December 2010 at Peking Union Medical College Hospital. A 1 : 1 cohort of patients with the same diagnosis who did not receive HRT were matched by age and stage. An analysis of both progression-free survival and overall survival was performed using Cox proportional hazards models.

RESULTS

According to the univariate analysis, HRT did not significantly influence progression-free or overall survival. Similarly, different types of HRT (estrogen alone, tibolone alone or an estrogen-tibolone combination) had no significant effect on the prognosis of epithelial ovarian cancer patients. The FIGO stage, differentiation, histological type and resection status were significantly correlated with progression-free survival and, except for histological type, these factors also significantly influenced overall survival. Finally, the multivariate analysis demonstrated that the strongest independent variable in predicting both progression-free survival and overall survival was the FIGO stage of the disease.

CONCLUSION

This study supports the hypothesis that postoperative HRT does not have a negative effect on the progression-free and overall survival of epithelial ovarian cancer patients. However, a multicenter study is needed to support and extend our findings.

Elevated vascular endothelial growth factor levels induce hyperpermeability of endothelial cells in hantavirus infection

OBJECTIVE

To investigate the role of vascular endothelial growth factor (VEGF) in haemorrhagic fever with renal syndrome (HFRS).

METHODS

VEGF, soluble VEGF receptor (sVEGFR)-2, angiopoietin (Ang)-1, tumour necrosis factor (TNF)-α and interferon (IFN)-γ levels were measured in serum samples from 68 patients with HFRS. Cultured human umbilical vein endothelial cells (HUEVCs) were infected by Hantaan virus (HTNV) and/or stimulated with recombinant VEGF; dextran permeability of the cells was determined. Claudin-1 and vascular endothelial (VE)-cadherin levels were determined by real-time reverse transcription-polymerase chain reaction and Western blot analyses.

RESULTS

Serum VEGF, TNF-α and IFN-γ levels were significantly elevated, whereas sVEGFR2 and Ang-1 levels were reduced, during the acute phase of HFRS. In vitro cell permeability was unaffected by HTNV infection or VEGF stimulation alone, but the combination of HTNV infection and VEGF treatment significantly increased the permeability of endothelial cell monolayers in a time-dependent manner. Claudin-1 and VE-cadherin were downregulated at both the mRNA and protein level by combined HTNV infection and VEGF stimulation.

CONCLUSIONS

Elevated VEGF induced by HTNV infection may play an important role in the vascular hyperpermeability that is characteristic of HFRS.

Successful use of aromatase inhibitor letrozole in NOA with an elevated FSH level: a case report

Aromatase inhibitors inhibit the conversion of testosterone to oestrogens and could reduce serum oestradiol concentrations. Letrozole is one of aromatase inhibitors frequently used in treatment of men with oligospermia. We present the case of an infertile man with small testes and an elevated FSH level, which was diagnosed as NOA, hypospermatogenesis proven by testicular biopsy. After taking letrozole for 3 months, semen analyses by computer-aided sperm analysis present that this man had normal spermatogenesis. This is the first case report of the activation of spermatogenesis, in man who was NOA with elevated FSH level, resulting from the use of the one of aromatase inhibitors.

Nonlinear elastic instability in channel flows at low Reynolds numbers

It is presently believed that flows of viscoelastic polymer solutions in geometries such as a straight pipe or channel are linearly stable. Here we present experimental evidence that such flows can be nonlinearly unstable and can exhibit a subcritical bifurcation. Velocimetry measurements are performed in a long, straight microchannel; flow disturbances are introduced at the entrance of the channel system by placing a variable number of obstacles. Above a critical flow rate and a critical size of the perturbation, a sudden onset of large velocity fluctuations indicates the presence of a nonlinear subcritical instability. Together with the previous observations of hydrodynamic instabilities in curved geometries, our results suggest that any flow of polymer solutions becomes unstable at sufficiently high flow rates.

Downregulation of 14-3-3β and 14-3-3ζ in lesions of psoriasis vulgaris

BACKGROUND

The 14-3-3 proteins are a family of conserved regulatory molecules expressed in all eukaryotic cells, which play essential roles in a wide range of vital regulatory processes, including differentiation, proliferation and transformation. In mammalian cells, seven 14-3-3 isoforms (β, γ, ε, η, θ/τ, σ and ζ) have been identified, and each of these seems to have distinct tissue localizations and isoform-specific functions. 14-3-3β and 14-3-3ζ are two important members of the 14-3-3 family.

AIM

To explore the role of 14-3-3β and 14-3-3ζ in normal skin and psoriasis vulgaris (PV) skin.

METHODS

Using immunohistochemistry and western blotting, we measured expression of 14-3-3β and 14-3-3ζ in 30 PV lesions and 15 normal skin samples. The average optical density (OD) of immunostaining and the relative grey scale of immunoblotting for 4-3-3β and 14-3-3ζ were analysed by the t-test.

RESULTS

The average OD of immunostaining for 14-3-3β and 14-3-3ζ was 0.17 ± 0.00 and 0.24 ± 0.01, respectively, in psoriatic lesions, which was significantly lower than in normal controls (0.22 ± 0.01 and 0.37 ± 0.02, respectively; P < 0.01 for both). There was also a significant difference in the relative grey scale of 14-3-3β and 14-3-3ζ (0.52 ± 0.03 and 1.44 ± 0.06, respectively) in psoriatic lesions compared with normal control tissue (3.32 ± 0.15 and 2.76 ± 0.11, respectively; P < 0.01 for both).

CONCLUSIONS

Expression of 14-3-3β and 14-3-3ζ were lower in psoriatic lesions than in normal human skin tissue. We speculate that 14-3-3β and 14-3-3ζ may be involved in the regulation of normal skin function, thus decreased expression of 14-3-3β and 14-3-3ζ might precipitate the disturbance in proliferation and differentiation of keratinocytes seen in psoriasis.

Lack of evidence on Tai Chi-related effects in patients with type 2 diabetes mellitus: a meta-analysis

AIMS

Whether Tai Chi (TC) benefits patients with type 2 diabetes mellitus (T2DM) remains controversial. Thus, we performed a meta-analysis to assess the efficacy of TC in T2DM patients.

METHODS

A computerised search through PubMed and Embase was performed to identify relevant studies. The primary outcomes were fasting blood glucose (FBG), haemoglobin A1c (HbA1c) and insulin resistance (HOMA). Secondary outcomes included total cholesterol, high-density lipoprotein cholesterol (HDL-C) and triglyceride. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated.

RESULTS

4 randomised controlled trials (RCTs) and 5 non-randomised controlled trials (NRCTs) met the inclusion criteria. The pooled WMDs from RCTs were -14.82 mg/dL (95% CI: -49.17 to 19.53; P=0.40) for FBG, -0.19% (95% CI: -0.41 to 0.03; P=0.09) for HbA1c and -0.34 units (95% CI: -3.02 to 2.34; P=0.80) for HOMA. The WMDs from NRCTs were -11.22 mg/dL (95% CI: -18.58 to -3.86; P=0.003) for FBG, -0.41% (95% CI: -0.53 to -0.29; P<0.00001) for HbA1c and -0.60 units (95% CI: -1.46 to 0.25; P=0.16) for HOMA. Furthermore, the pooled results of serum lipids suggest that TC significantly reduced triglyceride (P=0.006) instead of total cholesterol (P=0.77), and failed to improve HDL-C (P=0.12).

CONCLUSIONS

Sufficient evidence to support the benefits of TC to T2DM patients is lacking. Further large-scale studies are needed to investigate the long-term efficacy of TC.

Rheology of human blood plasma: viscoelastic versus Newtonian behavior

We investigate the rheological characteristics of human blood plasma in shear and elongational flows. While we can confirm a Newtonian behavior in shear flow within experimental resolution, we find a viscoelastic behavior of blood plasma in the pure extensional flow of a capillary breakup rheometer. The influence of the viscoelasticity of blood plasma on capillary blood flow is tested in a microfluidic device with a contraction-expansion geometry. Differential pressure measurements revealed that the plasma has a pronounced flow resistance compared to that of pure water. Supplementary measurements indicate that the viscoelasticity of the plasma might even lead to viscoelastic instabilities under certain conditions. Our findings show that the viscoelastic properties of plasma should not be ignored in future studies on blood flow.

Scanning tunneling microscope-quartz crystal microbalance study of temperature gradients at an asperity contact

Investigations of atomic-scale friction frequently involve setups where a tip and substrate are initially at different temperatures. The temperature of the sliding interface upon contact has thus become a topic of interest. A method for detecting initial tip-sample temperature differences at an asperity contact is described, which consists of a scanning tunneling microscope (STM) tip in contact with the surface electrode of a quartz crystal microbalance (QCM). The technique makes use of the fact that a QCM is extremely sensitive to abrupt changes in temperature. In order to demonstrate the technique's capabilities, QCM frequency shifts were recorded for varying initial tip-substrate temperature differences as an STM tip was brought into and out of contact. The results are interpreted within the context of a recent model for thermal heat conduction at an asperity contact, and it is concluded that the transient frequency response is attributable to small changes in temperature close to the region of contact rather than a change in the overall temperature of the QCM itself. For the assumed model parameters, the results moreover reveal substantial temperature discontinuities at the boundary between the tip and the sample, for example, on the order of 10-15 °C for initial temperature differences of 20 °C.