SU-E-T-10: Monte Carlo Study of the Dose Enhancement Factor (DEF) for Gold Nano-Particle (GNP) on the Cellular Level

PURPOSE

In megavoltage external beam radiotherapy, in vivo cell experiments suggest GNP could be used as a radiosensitizer by having radiation dose enhancement factor (DEF) significantly larger than 1. However, Monte Carlo (MC) simulations published in the literature failed to give prove, in which most of them only simulated the interactions between the radiation beams and a single GNP. In this study, we built a multi-GNPs model considering possible spatial arrangements of GNPs relative to a cell to calculate the DEFs of GNPs.

METHODS

Geant4 MC code with G4DNA physics model which can trace electrons down to eV level was used. Two types of geometry models representing different GNP-cell binding were created with each GNP modeled individually: (1) shell model with GNPs randomly and sparsely distributed in a shell in water mimicking when the GNPs were binding to the cell membrane, and (2) sphere model with GNPs randomly and sparsely distributed in a sphere in water mimicking when GNPs were floating inside the cytoplasm. Photon and electron spectrum at 5 cm in depth in water from a Varian 6MV beam was used as the radiation source. Dose to water inside the shell or the sphere representing cytoplasm were scored and compared to situations without GNPs to calculate the DEF. We also looked into the variation of DEFs due to different GNP sizes and concentrations.

RESULTS

A 35 um water cubic were successfully built in Geant4 with spatial resolution of 100 nm. Preliminary results shown under 200 keV electron irradiation, 100 nm GNPs in the shell model shown increased dose to cell at the beam entrance (DEF = 1.08).

CONCLUSIONS

The computation is undergoing for different GNP sizes and concentrations. Meaningful results are expected on the completion of this study.

Identification of a specific scar marker for detection of Tilletia foetida (Wall) Liro pathogen of wheat

Common bunt is one of the most important destructive diseases of wheat worldwide and is a domestic quarantined disease in China. However, a rapid and efficient method to identify the corresponding pathogens is currently limited. The objective of the present study was to develop a diagnostic molecular marker specific towards Tilletia foetida (Wall) Liro, a causal agent of the bunt disease. One specific DNA fragment for T. foetida (286 bp in length) was amplified using an Amplified Fragment Length Polymorphism (AFLP) assay and, this fragment was cloned and sequenced. One pair of specific primers (SC(286-1)/SC(286-2)), which was designed according to the sequence, could specifically amplify the corresponding fragment in all of the T. foetida isolates employed from both the People's Republic of China and United States, whereas this fragment could not be amplified by the other fungal species tested. Therefore, a specific Sequence Characterized Amplified Region (SCAR) marker was developed. This SCAR marker could distinguish T. foetida from related pathogenic fungi efficiently and could be used for the early diagnosis of the common bunt of wheat in the field, and provide an efficient way for disease surveillance and disease forecasting in cereal crop.

Prevalence and risk factors of diabetic retinopathy in Chongqing pre-diabetes patients

PURPOSE

To investigate the prevalence of diabetic retinopathy (DR) and relative risk factors among Chongqing pre-diabetes patients.

METHODS

A total of 750 participants were recruited in this cross-sectional study. All participants underwent a complete physical examination and an oral glucose-tolerance test. In all, 110 of the 125 newly diagnosed pre-diabetics and their healthy spouses as controls were examined with fluorescence fundus angiographies, and their blood with biochemical analyses. All the pre-diabetics with DR (23 subjects), 23 normal controls and 23 pre-diabetics without DR were compared for serum concentrations of regulated upon activation, normal T-expressed and secreted (RANTES). Student's t-test was used to compare continuous variables, and χ (2) test and analysis of variance to compare proportions among groups. Multiple logistic regression models were used to determine the risk factors for DR in pre-diabetics.

RESULTS

In all, 20.91% of the 110 pre-diabetics showed mild non-proliferative DR (NPDR). There was a statistically significant difference in serum concentrations of RANTES between pre-diabetics with and without DR (P<0.01), and also between pre-diabetics with DR and normal controls (P<0.01). However, age, body mass index, waist-hip ratio, triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein-C, low-density lipoprotein-C, blood urea nitrogen, blood creatinine, and urine albumin excretion rate seemed to have no reliable relationship with DR in pre-diabetics (P>0.05).

CONCLUSION

The prevalence of DR in Chongqing pre-diabetes patients in the study was about 20.91% and only mild NPDR was found. It seems that RANTES is one possible risk factor associated with DR in pre-diabetics, not age, TG and TC, and others.

Electroacupuncture inhibition of hyperalgesia in an inflammatory pain rat model: involvement of distinct spinal serotonin and norepinephrine receptor subtypes

BACKGROUND

Although acupuncture analgesia is well documented, its mechanisms have not been thoroughly clarified. We previously showed that electroacupuncture (EA) activates supraspinal serotonin- and norepinephrine-containing neurones that project to the spinal cord. This study investigates the involvement of spinal alpha(2)-adrenoceptors (α2-ARs) and 5-hydroxytryptamine (serotonin) receptors (5-HTRs) in EA effects on an inflammatory pain rat model.

METHODS

Inflammatory hyperalgesia was induced by injecting complete Freund's adjuvant (CFA, 0.08 ml) into the plantar surface of one hind paw and assessed by paw withdrawal latency (PWL) to a noxious thermal stimulus. The selective α2a-AR antagonist BRL-44408, α2b-AR antagonist imiloxan hydrochloride, 5-HT2B receptor (5-HT2BR) antagonist SB204741, 5-HT3R antagonist LY278584, or 5-HT1AR antagonists NAN-190 hydrobromide, or WAY-100635 were intrathecally administered 20 min before EA or sham EA, which was given 2 h post-CFA at acupoint GB30.

RESULTS

EA significantly increased PWL compared with sham [7.20 (0.46) vs 5.20 (0.43) s]. Pretreatment with α2a-AR [5.35 (0.45) s] or 5-HT1AR [5.22 (0.38) s] antagonists blocked EA-produced anti-hyperalgesia; α2b-AR, 5-HT2BR, and 5-HT3R antagonist pretreatment did not. Sham plus these antagonists did not significantly change PWL compared with sham plus vehicle, indicating that the antagonists had little effect on PWL. Immunohistochemical staining demonstrated that α2a-ARs are on primary afferents and 5-HT1ARs are localized in N-methyl-d-aspartic acid (NMDA) subunit NR1-containing neurones in the spinal dorsal horn.

CONCLUSIONS

The data show that α2a-ARs and 5-HT1ARs are involved in the EA inhibition of inflammatory pain and that the NMDA receptors are involved in EA action.

High TPMT enzyme activity does not explain drug resistance due to preferential 6-methylmercaptopurine production in patients on thiopurine treatment

BACKGROUND

Up to 20% of patients on thiopurine therapy fail to achieve adequate drug response. Many of these patients preferentially produce the toxic 6-methylmercaptopurine metabolites (6-MMP) rather than the active 6-thioguanine nucleotides (6-TGN) resulting in a high 6-MMP/6-TGN ratio (>20) and increased risk of hepatotoxicity.

AIM

To determine the prevalence of preferential 6-MMP producers and define the relationships between 6-TGN, 6-MMP and thiopurine methyltransferase (TPMT).

METHODS

The database of 6-TGN, 6-MMP and TPMT measurements from patients throughout New Zealand was used to calculate patients' 6-MMP/6-TGN ratios and identify those with high (>20) or normal ratio (≤20).The TPMT enzyme activity was compared amongst the groups.

RESULTS

Of 1879 patients with TPMT, 6-TGN and 6-MMP results, 349 (19%) had a 6-MMP/6-TGN ratio >20. The mean TPMT enzyme activity was slightly lower for those with a 6-MMP/6-TGN ratio ≤20 vs. >20, which achieved statistical significance (12.2 vs. 13.2; P < 0.001). However, the distributions of TPMT enzyme activity were similar, with 97% of TPMT results falling between 5.0 and 17.6 IU/mL for both groups. In all, 17% of those with 6-MMP/6-TGN ratio ≤20 were intermediate TPMT metabolisers (TPMT 5.0-9.2 IU/mL) vs. 7% in those with a ratio >20.

CONCLUSIONS

In this patient population with measured 6-MMP/6-TGN ratios, 19% of patients were preferential 6-MMP producers. The results show that high TPMT enzyme activity is not the major reason for preferential 6-MMP production in most patients with a high metabolite ratio. This suggests that there are one or more important alternative mechanisms for preferentially producing 6-MMP.

First Report of the Lesion Nematode, Pratylenchus agilis, Parasitizing Wheat in China

Wheat (Triticum aestivum L.) fields in Zhengzhou, Henan Province that exhibited reduced height and number of tillers were surveyed in 2008, and samples were collected for analyses. Fifteen of thirty-five samples contained a nematode suspected of causing small, brown lesions in roots. Both lateral roots and root hairs were reduced in infected plants. Nematode presence was associated with enlarging lesions and necrotic roots. We also observed lesion nematode infestation in samples with no symptoms in the roots. During the growing season, wheat yield increased by 14% with nematocide treatments in Zhengzhou suburb fields. The morphological and molecular analyses of the nematodes isolated from soil samples established the identity of the species as the lesion nematode, Pratylenchus agilis (2,3). Morphological characteristics that were used for identification included female body, lip annules, tail terminus, number of lines in the lateral field, stylet knobs, stylet length, and vulva location in relation to body length. Females were cylindrical, measured 452 to 811 μm long, and contained two lip annules, a smooth tail terminus, four lateral lines, a vulva at 72.64 to 79.97%, a stylet of 16.20 to 17.55 μm, basal esophageal lobes elongated less than twice the body width, and stylet knobs rounded posteriorly. Males were rare and the spermatheca was empty. Molecular analysis was conducted by amplifying the internal transcribed spacer (ITS) regions ITS1 and 2. Sequence of ITS regions from this population (GenBank Accession No. JQ039330) showed highest sequence homology to P. agilis isolate PagKL5 (GenBank Accession No. FJ71289.1) with the identity of 90%. High variability at species level has been found for Pratylenchus species (1). On the basis of the morphological traits and molecular analyses, the nematodes were identified as P. agilis. To our knowledge, this is the first report of P. agilis parasitizing wheat. References: (1) F. De Luca et al. Eur. J. Plant Pathol. 130:415, 2011. (2) A. M. Golden et al. Plant Dis. Rep. 62:430, 1978. (3) R. V. Rebois et al. J. Nematol. 18:392, 1986.

Right lobe living-donor liver transplantation with or without middle hepatic vein: a meta-analysis

OBJECTIVE

The purpose of this meta-analysis was to compare outcomes after right-lobe living-donor liver transplantation (LDLT) with or without the middle hepatic vein (MHV).

METHODS

Studies were identified through a computerized search of Pubmed, Embase, Ovid, the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials, the Cochrane Library database, and the Web of Science. Two reviewers independently assessed the quality of each study and abstracted outcome data. We extracted data for liver functional recovery in donors, donor hospital stay, donor complications and liver functional recovery in recipients. We synthesized published data using random-effects and fixed-effect models, expressing results as weighted mean differences (WMD) or relative risk (RR).

RESULTS

The 11 included eligible studies came from medical centers worldwide. Significant differences between "with MHV" versus "without MHV" groups were not observed for liver functional recovery (P=.08; WMD=-2.88), donor hospital stay (P=.00; WMD=0.00), or donor complications (P=.90; RR=1.02). However, our meta-analysis showed a significant benefit for recipients liver functional recovery favoring the MHV group (P=.02; WMD=-33.06).

CONCLUSIONS

Our meta-analysis discovered that right lobes with MHV not only experienced better liver functional recovery in recipients, but also caused no greater harm or risk to donors.

S100A4 regulates motility and invasiveness of human esophageal squamous cell carcinoma through modulating the AKT/Slug signal pathway

The involvement of S100A4 in modulating invasiveness of esophageal squamous cell carcinoma (ESCC) cell lines was explored. It was shown that S100A4 expression is positively correlated with the degree of invasiveness in human ESCC cells. The S100A4-rich EC-1 cells displayed higher migratory and invasive cell behavior while ET-1 cells with low S100A4 expression levels displayed lower migratory and invasive cell behavior. S100A4 silencing by small interfering (siRNA) in EC-1 cells induced E-cadherin expression, and overexpression of S100A4 in a lowly invasive TE-1 cells suppressed E-cadherin expression. It is suggested that S100A4 silencing inhibit invasion via E-cadherin upregulation, and overexpression of S100A4 promote invasion via E-cadherin downregulation in ESCC cells. Compared with the vector-transfected cells, S100A4 silencing in EC-1 cells showed reduced ability of migration and invasiveness, and overexpression of S100A4 in TE-1 cells showed increased ability of migration and invasiveness via wound-healing and Transwell assay, and pseudometastatic model assay. Furthermore, re-expression of S100A4 could increase the invasive phenotypes in S100A4 siRNA transfected EC-1 cells, and S100A4 silencing could decrease the invasive phenotypes in S100A4 circular DNA (cDNA) transfected TE-1 cells. It was found that Slug is downregulated in S100A4 siRNA transfected EC-1 cells, and Slug is upregulated in S100A4 cDNA transfected TE-1 cells. It was also discovered S100A4 cDNA induced protein kinase B (AKT) phosphorylation at Serine-473(phospho-AKT [p-AKT]) levels, followed by the Slug upregulation, and S100A4 siRNA decreases the phospho-AKT levels, followed by the Slug downregulation. The data suggested that S100A4 could regulate migratory and invasive behavior of human ESCC cells through modulating AKT/Slug pathway.

Coenzyme Q(10) enhances dermal elastin expression, inhibits IL-1α production and melanin synthesis in vitro

Coenzyme Q(10) (CoQ(10) ) is a well-known antioxidant and has been used in many skincare products for anti-ageing purpose. However, the molecular mechanisms of CoQ(10) function in skin cells are not fully understood. In this paper, we compared the effects of CoQ(10) on primary human dermal fibroblasts from three individuals, including adult. We demonstrated that CoQ(10) treatment promoted proliferation of fibroblasts, increased type IV collagen expression and reduced UVR-induced matrix metalloproteinases-1 (MMP-1) level in embryonic and adult cells. In addition, CoQ(10) treatment increased elastin gene expression in cultured fibroblasts and significantly decreased UVR-induced IL-1α production in HaCat cells. Taken together, CoQ(10) presented anti-ageing benefits against intrinsic ageing as well as photo damage. Interestingly, CoQ(10) was able to inhibit tyrosinase activity, resulting in reduced melanin content in B16 cells. Thus, CoQ(10) may have potential depigmentation effects for skincare.

REGγ is a strong candidate for the regulation of cell cycle, proliferation and the invasion by poorly differentiated thyroid carcinoma cells

REGγ is a proteasome activator that facilitates the degradation of small peptides. Abnormally high expression of REGγ has been observed in thyroid carcinomas. The purpose of the present study was to explore the role of REGγ in poorly differentiated thyroid carcinoma (PDTC). For this purpose, small interfering RNA (siRNA) was introduced to down-regulate the level of REGγ in the PDTC cell line SW579. Down-regulation of REGγ at the mRNA and protein levels was confirmed by RT-PCR and Western blot analyses. FACS analysis revealed cell cycle arrest at the G₁/S transition, the MTT assay showed inhibition of cell proliferation, and the Transwell assay showed restricted cell invasion. Furthermore, the expression of the p21 protein was increased, the expression of proliferating cell nuclear antigen (PCNA) protein decreased, and the expression of the p27 protein was unchanged as shown by Western blot analyses. REGγ plays a critical role in the cell cycle, proliferation and invasion of SW579 cells. The alteration of p21 and PCNA proteins related to the down-regulation of REGγ suggests that p21 and PCNA participate in the process of REGγ regulation of cell cycle progression and cell proliferation. Thus, targeting REGγ has a therapeutic potential in the management of PDTC patients.

Epidemiological and clinical characteristics of the outbreak of 2009 pandemic influenza A (H1N1) at a middle school in Luoyang, China

OBJECTIVES

To describe the epidemiological and clinical characteristics of 2009 H1N1 influenza, particularly the incubation period and the duration of symptoms, and to assess the public health response to this outbreak.

STUDY DESIGN

A retrospective cohort study was conducted among all students and employees in a middle school by telephone survey and laboratory inspection.

METHODS

Nasopharyngeal specimens were collected and tested, and real-time reverse transcriptase polymerase chain reaction testing was performed to confirm the viral infection. The epidemiological and clinical characteristics were obtained through a telephone survey, and the incubation period and the duration of symptoms associated with 2009 H1N1 influenza were estimated by parametric distribution.

RESULTS

In total, 253 cases of influenza-like illness were found among students and employees, and 79 of these cases were confirmed as H1N1 infection through laboratory inspection. The response rate for the telephone survey was 93.48% for the students (2586/2768) and 85.87% for the employees (158/184). The average attack rate was 9.22% (253/2744). The main reported symptoms were fever (100%), cough (74.68%), sore throat (59.49%), headache (56.96%) and myalgia/arthralgia (51.90%). No complications were reported and no deaths occurred. The confirmed and suspected cases had no associated travel history or contact with a confirmed or probable case. The estimated median incubation period was 1.6 days [95% confidence interval (CI) 1.2-2.3]. The duration of symptoms was 3-11 days, and the median duration of symptoms was 7.5 days (95% CI 4.5-10.5).

CONCLUSIONS

The results suggest that the outbreak of 2009 H1N1 influenza in this middle school was widespread but not severe. The natural history of 2009 H1N1 influenza virus appears to be similar to that of previously circulating pandemic and interpandemic influenza viruses. The public health response indicates that school closure could have a substantial impact on the spread of 2009 H1N1 influenza.

Deuteron injector for Peking University Neutron Imaging Facility project

The deuteron injector developed for the PKUNIFTY (Peking University Neutron Imaging Facility) has been installed and commissioned at Peking University (PKU). The injector system must transfer 50 keV 50 mA of D(+) ion beam to the entrance of the 2 MeV radio frequency quadrupole (RFQ) with 10% duty factor (1 ms, 100 Hz). A compact 2.45 GHz permanent magnet electron cyclotron resonance (PMECR) ion source and a 1.36 m long low energy beam transport (LEBT) line using two solenoids was developed as the deuteron injector. A φ5 mm four-quadrant diaphragm was used to simulate the entrance of RFQ electrodes. The beam parameters are measured after this core with an emittance measurement unit (EMU) and a bending magnet for ion fraction analysis at the end of injector. During the commissioning, 77 mA of total deuteron beam was extracted from PMECR and 56 mA of pure D(+) beam that passed through the φ5 mm four-quadrant diaphragm was obtained at the position of RFQ entrance with the measured normalized rms emittance 0.12-0.16π mm mrad. Ion species analysis results show that the deuteron fraction is as high as 99.5%. All of the parameters satisfy PKUNIFTY's requirements. In this paper, we will describe the deuteron injector design and report the commissioning results as well as the initial operation.

Inhibition of sphingosine kinase 1 suppresses proliferation of glioma cells under hypoxia by attenuating activity of extracellular signal-regulated kinase

OBJECTIVES

Sphingosine kinase (SphK), which is regulated by hypoxia, catalyses phosphorylation of sphingosine to produce sphingosine-1-phosphate, which stimulates invasiveness of gliomas. However, whether SphK is involved in proliferation of glioma cells under hypoxic conditions is not clearly understood. In this study, we have investigated the role of SphK in of proliferation glioma cells under hypoxia.

MATERIALS AND METHODS

  Effects of small interfering RNA (siRNA) on SphKs, SKI (inhibitor of SphK) and U0126 (inhibitor of ERK) on proliferation of glioma cells under hypoxia were studied using CCK-8 assay and flow cytometry. Protein expression profiles were evaluated by Western blot analysis.

RESULTS

SKI suppressed proliferation of glioma cells under hypoxia. Similarly, downregulation of SphKs by siRNA inhibited glioma cell proliferation, and the cell cycle was arrested in G(2) /M phase when SphK1 was inhibited. In addition, inhibition of SphK1 attenuated phosphorylation of ERK in hypoxic conditions. Furthermore, U0126 markedly inhibited cell population growth and arrested cells in G(2) /M as effectively as SKI. However, silencing SphK2 induced cell cycle arrest in the S phase and it showed little effect on hypoxia-induced activation of ERK.

CONCLUSIONS

  SphK1 and SphK2 are involved in proliferation of glioma cells in hypoxic conditions through distinct signalling pathways. SphK1, but not SphK2, promotes cell population expansion in hypoxic conditions by activating ERK.

Mesoporous SnO2@carbon core-shell nanostructures with superior electrochemical performance for lithium ion batteries

SnO2@carbon nanostructure composites are prepared by a simple hydrothermal method. The composite exhibits unique structure, which consists of a mesoporous SnO2 core assembled of very small nanoparticles and a carbon shell with 10 nm thickness. The mesoporous SnO2@carbon core-shell nanostructures manifest superior electrochemical performance as an anode material for lithium ion batteries. The reversible specific capacity of the composite is about 908 mAh g(-1) for the first cycle and it can retain about 680 mAh g(-1) after 40 charge/discharge cycles at a current density of 0.3 C. Moreover, it shows excellent rate capability even at the high rate of 4.5 C. The enhanced performance was attributed to the mesoporous structure and a suitable carbon coating.