Evaluation of cesium-137 conversion models and parameter sensitivity for erosion estimation

The Cs technique has been widely used to provide soil redistribution estimates since the 1970s. However, most Cs-conversion models remain theoretical and largely unvalidated. Our objectives were to validate the four widely used conversion models, examine model parameter sensitivity, and evaluate the potential of using kriging to improve soil redistribution estimation. Soil loss was measured from a 1.6-ha plot since 1978. Winter wheat ( L.) was grown primarily under conventional tillage. Soil samples in a 10-m grid were taken from the plot to estimate the Cs inventory. Soil redistribution rates were estimated using four models and were further interpolated using ordinary kriging. The parameter sensitivity analyses at the 95% confidence limits showed that reference inventory had the most impact on estimated water erosion, followed by particle size correction for erosion and tillage depth, with minimal impacts from mass depth, bulk density, and particle size correction for deposition. Compared with the measured water erosion, the relative errors of the mean net water erosion estimates across the entire plot without and with kriging were 28 and -17% for the proportional model (PM), 141 and 106% for the simplified mass balance model, 133 and 100% for the improved mass balance model (MBM2), and 109% for the extended MBM2 with tillage erosion (MBM3). Results indicated that the PM performed better than the mass balance models under the study conditions and that kriging improved mean soil redistribution estimates. However, the full potential of the MBM2 and MBM3 needs to be further evaluated under conditions where loss of newly deposited Cs exists.

A novel in vitro assay for assessing efficacy and toxicity of antifungals using human leukaemic cells infected with Candida albicans

AIMS

This study describes a novel in vitro assay that simultaneously determines antifungal efficiency and host cell toxicity using suspensions of human leukaemic cells (HL-60) infected with Candida albicans.

METHODS AND RESULTS

The effect of Candida infection on host cell viability was evaluated by the microscopy of trypan blue-stained cells and lactate dehydrogenase (LDH) activity. The in vitro 'drug potency assay' utilized the Cell Counting Kit-8 and measured post-antifungal treatment viability of Candida-infected HL-60 cells and the ability of the antifungal treatment to prevent infection. LDH activity showed that 42% ± 4·0 and 85·3% ± 7·40 of HL-60 cells were killed following Candida infection at the multiplicity of infection (MOI) of 1 : 1 and 1 : 5, respectively. The antifungal nystatin (0·78-25 μmol l(-1) ) was found to inhibit C. albicans infection as seen by the significantly increased viability of HL-60 cells. Cytotoxicity of nystatin towards infected HL-60 cells was evident at higher concentrations and this was also confirmed by propidium iodide staining.

CONCLUSIONS

An assay using undisturbed cell suspension conditions was successfully developed for assessing the selectivity of the antifungal therapy in the host-Candida environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

The assay employing Candida infection of host cell suspensions represents a promising method for testing interactions of antifungal compounds with both fungal and host cells.

Towards a resolution of the proton form factor problem: new electron and positron scattering data

There is a significant discrepancy between the values of the proton electric form factor, G(E)(p), extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of G(E)(p) from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ϵ) and momentum transfer (Q(2)) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ϵ at Q(2)=1.45  GeV(2). This measurement is consistent with the size of the form factor discrepancy at Q(2)≈1.75  GeV(2) and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3  GeV(2).

Longitudinal target-spin asymmetries for deeply virtual compton scattering

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep→e^{'}p^{'}γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ϕ, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

MiR-873 regulates ERα transcriptional activity and tamoxifen resistance via targeting CDK3 in breast cancer cells

miRNAs (microRNAs) are frequently and aberrantly expressed in many cancers. MiR-873 has been revealed to be downregulated in colorectal cancer and glioblastoma. However, its function remains unclear. Here we report that miR-873 is downregulated in breast tumor compared with normal tissue. Enforced expression of miR-873 decreases the transcriptional activity of ER (estrogen receptor)-α but not ERβ through the modulation of ERα phosphorylation in ER-positive breast cancer cells. We also found that miR-873 inhibits breast cancer cell proliferation and tumor growth in nude mice. Reporter gene assays revealed cyclin-dependent kinase 3 (CDK3) as a direct target of miR-873. CDK3 was shown to be overexpressed in breast cancer and phosphorylate ERα at Ser104/116 and Ser118. Furthermore, we found that Mir-873 inhibits ER activity and cell growth via targeting CDK3. Interestingly, miR-873 was observed to be downregulated in tamoxifen-resistant MCF-7/TamR cells, while CDK3 is overexpressed in these cells. More importantly, re-expression of miR-873 reversed tamoxifen resistance in MCF-7/TamR cells. Our data demonstrate that miR-873 is a novel tumor suppressor in ER-positive breast cancer and a potential therapeutic approach for treatment of tamoxifen-resistant breast cancer.

Kinome-wide screening of HER2+ breast cancer cells for molecules that mediate cell proliferation or sensitize cells to trastuzumab therapy

Understanding the signaling differences that distinguish human HER2-amplified (HER2-positive (HER2+)) breast cancers from other breast cancer subtypes may help to identify protein drug targets for the specific treatment of HER2+ breast cancers. We performed two kinome-wide small interfering RNA (siRNA) screens on five HER2+ breast cancer cell lines, seven breast cancer cell lines in which HER2 was not amplified and two normal breast cell lines. To pinpoint the main kinases driving HER2 signaling, we performed a comprehensive siRNA screen that identified loss of the HER2/HER3 heterodimer as having the most prominent inhibitory effect on the growth of HER2+ breast cancer cells. In a second siRNA screen focused on identifying genes that could sensitize HER2+ cells to trastuzumab treatment, we found that loss of signaling members downstream of phosphatidylinositol 3 kinase (PI3K) potentiated the growth inhibitory effects of trastuzumab. Loss of HER2 and HER3, as well as proteins involved in mitogenic and environmental stress pathways inhibited the proliferation of HER2+ cells only in the absence of trastuzumab, suggesting that these pathways are inhibited by trastuzumab treatment. Loss of essential G2/M cell cycle mediators or proteins involved in vesicle organization exerted inhibitory effects on HER2+ cell growth that were unaffected by trastuzumab. Furthermore, the use of a sensitization index (SI) identified targeting the PI3K pathway to sensitize to trastuzumab treatment. Antagonism using the SI identified MYO3A, MYO3B and MPZL1 as antagonizers to trastuzumab treatment among HER2+ cell lines. Our results suggest that the dimerization partners of HER2 are important for determining the activation of downstream proliferation pathways. Understanding the complex layers of signaling triggered downstream of HER2 homodimers and heterodimers will facilitate the selection of better targets for combination therapies intended to treat HER2+ breast cancers.

Subarachnoid hemorrhage: role of subtraction CT angiography in etiological diagnosis and pretreatment planning

AIM

Subarachnoid hemorrhage (SAH) is a deleterious cerebrovascular disorder that requires prompt etiological diagnosis. We wished to evaluate the diagnostic performance of the latest generation 3D subtraction CT angiography (CTA) in etiological diagnosis and pretreatment planning of patients with suspected SAH.

METHODS

A total of 88 patients were included in our study and underwent both 3D subtraction CTA and digital subtraction angiography (DSA) examinations. The 3D subtraction CTA images were reviewed by two independent readers who were blinded to the results of DSA. Sensitivity, specificity, positive and negative predictive values of 3D subtraction CTA were calculated on a per-patient basis. The possibility for surgical treatment was also evaluated based on information provided by CTA alone.

RESULTS

According to DSA results, 72 patients were diagnosed with ruptured intracranial aneurysms, 5 patients with arteriovenous malformations, and no lesion was detected in 11 patients. Sensitivity, specificity, positive predictive value and negative predictive values of CTA for etiological evaluation of SAH were all 100%. Correct pretreatment decision was made in 67 of 70 patients based on the CTA measurements alone.

CONCLUSION

THE results of our study indicate that 3D subtraction CTA is an accurate, fast and non-invasive imaging modality that is equal to DSA in etiological evaluation and pretreatment planning of patients with suspected SAH. It may replace DSA as the first step imaging method in patients with suspected SAH, while DSA should still be reserved for case of uncertainty.

Dimethyl fumarate attenuates 6-OHDA-induced neurotoxicity in SH-SY5Y cells and in animal model of Parkinson's disease by enhancing Nrf2 activity

Oxidative stress is central to the pathology of several neurodegenerative diseases, including Parkinson's disease (PD), and therapeutics designed to enhance antioxidant potential could have clinical value. In this study, we investigated whether dimethyl fumarate (DMF) has therapeutic effects in cellular and animal model of PD, and explore the role of nuclear transcription factor related to NF-E2 (Nrf2) in this process. Treatment of animals and dopaminergic SH-SY5Y cells with DMF resulted in increased nuclear levels of active Nrf2, with subsequent upregulation of antioxidant target genes. The cytotoxicity of 6-hydroxydopamine (6-OHDA) was reduced by pre-treatment with DMF in SH-SY5Y cells. The increase in the reactive oxygen species caused by 6-OHDA treatment was also attenuated by DMF in SH-SY5Y cells. The neuroprotective effects of DMF against 6-OHDA neurotoxicity were dependent on Nrf2, since treatment with Nrf2 siRNA failed to block against 6-OHDA neurotoxicity and induce Nrf2-dependent cytoprotective genes in SH-SY5Y cells. In vivo, DMF oral administration was shown to upregulate mRNA and protein levels of Nrf2 and Nrf2-regulated cytoprotective genes, attenuate 6-OHDA induced striatal oxidative stress and inflammation in C57BL/6 mice. Moreover, DMF ameliorated dopaminergic neurotoxicity in 6-OHDA-induced PD animal models as evidenced by amelioration of locomotor dysfunction, loss in striatal dopamine, and reductions in dopaminergic neurons in the substantia nigra and striatum. Taken together, these data strongly suggest that DMF may be beneficial for the treatment of neurodegenerative diseases like PD.

Tetraploid complementation proves pluripotency of induced pluripotent stem cells derived from adipose tissue

OBJECTIVES

Recently, pluripotency of induced pluripotent stem (iPS) cells has been displayed after producing adult mice, in tetraploid complementation assays. These studies lead us to the last piece of the puzzle for reprogramming somatic cells into fully pluripotent cells which function as embryonic stem cells in most applications. However, in all of previous studies, skin fibroblasts were used as the starting population for reprogramming, raising questions as to whether the pluripotency of the iPS cells was dependent on the particular starting cell type.

MATERIALS AND METHODS

Our iPS cell lines were prepared from murine adipose stem cells (ASCs). Their multi-potency was first tested by teratoma formation in nude mice. Then, tetraploid complementation was performed to generate progeny from them.

RESULTS

We succeeded to the birth of viable and fertile adult mice derived entirely from reprogrammed ASC, indicating cell types other than fibroblasts can also be restored to the embryonic level of pluripotency.

CONCLUSIONS

We also directed differentiation of iPS cells into chondrocytes, thus adipose-derived iPS cells can be used as models to study chondrogenic differentiation and cartilage regeneration.

Genetic diversity and differentiation of the endangered and endemic species Sauvagesia rhodoleuca in China as detected by ISSR analysis

Sauvagesia rhodoleuca (Ochnaceae) is an endangered plant that is endemic to southern China. The levels of genetic variation and patterns of population structure in S. rhodoleuca were investigated using inter-simple sequence repeat markers. Eleven primers were used to amplify DNA samples from 117 individuals, and a total of 92 loci were detected. Our results indicated that genetic diversity was quite low both at the species level (percentage of polymorphic bands (PPB) = 41.30%, Nei's gene diversity (h) = 0.1331, and Shannon information index (I) = 0.2028) and the population level (PPB = 16.30-28.26%, h = 0.0496-0.1012, and I = 0.0756-0.1508). A high level of genetic differentiation among populations was detected based on Nei's genetic diversity analysis (0.4344) and analysis of molecular variance (47.03%). The low genetic diversity within population and high population differentiation of S. rhodoleuca were assumed to result largely from limited gene flow, genetic drift, inbreeding, and clonal growth. Conservation strategies for this endangered species are proposed based on the genetic data.

Strangeness suppression of qq creation observed in exclusive reactions

We measured the ratios of electroproduction cross sections from a proton target for three exclusive meson-baryon final states: ΛK(+), pπ(0), and nπ(+), with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization, we extract qq creation probabilities for the first time in exclusive two-body production, in which only a single qq pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to nonstrange pairs, similar to that seen in high-energy production.

Adipogenic differentiation potential of adipose-derived mesenchymal stem cells from ovariectomized mice

OBJECTIVES

In human post-menopausal osteoporosis, enhanced adipogenesis in bone marrow and enhanced formation of adipose tissue in vivo are observed. These changes correlate with reduced trabecular bone volume and increased adipocyte cell size as well as cell number. However, cellular and molecular mechanisms underlying osteoporosis-related changes in adipocyte cell volume are not known. This study was designed to compare adipogenic potential of adipose tissue-derived stem cells (ADSCs) obtained from ovariectomized mice with that of control ADSCs, and to analyse pathological mechanisms from the point of functional changes of ADSCs.

MATERIALS AND METHODS

Healthy female C57BL/6J mice were randomly divided into ovariectomy and sham-surgery groups. Mouse ADSCs were isolated and cultured in vitro up to passage 3. After adipogenic induction, oil red O staining of lipid droplets was used to detect adipogenic ability of ADSCs; real-time PCR and immunofluorescence staining were used to detect expression of adipogenesis-related genes and proteins.

RESULTS

As indicated by increased expression of adipogenic and lipogenic genes and proteins, and lipid droplets accumulation shown by oil red-O staining, adipogenic differentiation of ADSCs was significantly enhanced in the ovariectomy group compared to the sham-surgery group (P < 0.05).

CONCLUSION

These findings suggest that enhanced adipogenic differentiation of ADSCs is likely to be the important cause for increased adipogenesis in vivo and subsequent obesity-like changes in body mass, in mice, after ovariectomy.