Ultrafast Optical Responses of the Squarylium Dye J-Aggregates Films

Ultrafast optical responses of the organic films containing squaryliurn dye J-aggregates prepared by simple spincoating method were investigated. Some SQ films exhibited a sharp absorption peak originated from J-aggregates and especially the SQ derivative which has dibutylamino bases at the end of benzene rings forms good J-aggregates in the films without any extra treatment. Time-resolved difference absorption spectra were measured about the SQ44 film. Clear bleached absorption peak and its fast recovery were observed. The decay time was determined to be about 220 fs at 50 MW/cm2 excitation intensity. Sample preparations and all the measurements were performed in air at room temperature.

Concomitant increases in spectrum and level of drug resistance in Mycobacterium tuberculosis isolates

OBJECTIVE

To determine the drug resistance spectrum and resistance levels of extensively drug-resistant (XDR-) and multidrug-resistant tuberculosis (MDR-TB) and TB resistant to either rifampicin (RMP, R) or isoniazid (INH, H; R/H-DR).

DESIGN

Of 142 drug-resistant clinical isolates examined, 13 were XDR-TB, 66 were MDR-TB and 63 were R/H-DR. The drug resistance spectrum was tested by the absolute two-concentration method. Minimum inhibitory concentrations (MICs) were determined for the strains by agar dilution method on Löwenstein-Jensen slants.

RESULTS

The drug resistance spectrum of XDR-TB, MDR-TB and R/H-DR TB isolates ranged from 4 to 9, 2 to 6 and 1 to 5 drugs, respectively. Over half of all XDR-TB (53.8%), MDR-TB (66.7%) and R/H-DR (54.0%) isolates were resistant to two other anti-tuberculosis drugs; 38.5% of XDR-TB, 24.2% of MDR-TB and 28.6% of R/H-DR TB isolates were resistant to ≥ 3 additional anti-tuberculosis drugs in addition to those originally defined, demonstrating that the MIC values and the proportions of strains with higher MICs followed a trend of XDR-TB > MDR-TB > R/H-DR for INH, RMP, ofloxacin and ethambutol.

CONCLUSION

XDR-TB, MDR-TB and R/H-DR TB isolates exhibited both increasingly broader resistance spectra and a higher percentage of strains with high MICs to more frequently resistant drugs, which might be related to patterns of TB chemotherapy.

Proteasomes reactivator REG gamma enchances oncogenicity of MDA-MB-231 cell line via promoting cell proliferation and inhibiting apoptosis

To investigate the effect of proteasomes reactivator REG gamma on cell cycle and apoptosis in vitro and in vivo. In vitro, we first constructed recombinant plasmid of PcDNA3.1-REGgamma and then transfected REGgamma into MDA-MB-231 cell line. We confirmed the transfection efficiency by Western blot. Subsequently, we observed cell growth, cycle and colony formation. Specific proliferative molecule proliferating cell nuclear antigen (PCNA) and apoptosis related signal molecule Caspase-3 was assayed by immmunohistochemistry and absorption spectrometry, respectively. In vivo, we successfully established transplantation tumor nude mice model. We determined REGgamma mRNA level in the transplantation tumor tissue. Then, FCM was used to determine cell cycle, apoptosis and CD16. Finally, we employed immunohistochemistry to determine P21 positive expression. However, the cells transfected with REGgamma grew more rapidly compared with non-transfected ones. Increased cells were observed in S+G2+M phase and S phase in the REGgamma transfected group. PCNA expression level in the transfected cells was higher than that in non-transfected ones. In vivo, we observed the similar phenomenon including more rapid tumor growth, higher REGgamma mRNA expression, decreased cells number in G0/G1 phase and G2/M phase, increased cells in S phase and decreased apoptosis in the transfected group. In the study of related molecules, we also found related molecules P21 and CD16 positive expression rate were obviously lower than non-infected ones. In present study, we found oncogenicity of MDA-MB-231 cell transfected with REGgamma was enhanced, which might be realized via REGgamma promoting cell growth, inhibiting cell apoptosis, degrading P21 and suppressing activation of NK, suggesting REGgamma promoting tumor growth is a process involving multiple factor mechanisms.

Quantitative structure-property relationship studies on electrochemical degradation of substituted phenols using a support vector machine

A quantitative structure-property relationship (QSPR) model has been developed for the electrochemical degradation of substituted phenols using a support vector machine (SVM). Thirty descriptors, including quantum chemical parameters, steric effect descriptors and half wave potential (E1/2), were used for describing twelve substituted phenols, including mono- and multi-substituent phenols. A leave-one-out (LOO) cross validation procedure resulted in the selection of three descriptors, the total of electron and nuclear energies of the two-center terms for the carbon-chlorine or carbon-nitrogen bond (TE2), the net atomic charges on the chlorine or nitrogen (qx), and the largest negative atomic charge on an atom (q-). The model based on SVM yielded a Q2 value of 0.892, indicating a high predictive ability. Compared with models developed with partial least squares (PLS) and multiple linear regression (MLR), where Q2 were 0.804 and 0.799 respectively, SVM showed higher performances.

11C-Methionine PET to predict survival of glioma patients treated by radiotherapy

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Background: The early prediction of glioma prognosis is very important. Amino acid metabolism of glioma is associated with numerous catabolic processes favoring tumor growth. As an essential amino acid, L-methionine plays a central role in the altered metabolism of cancer cells. The aim of this study was to evaluate the prognostic value of PET imaging using 11C-methionine (MET) in patients with gliomas treated by radiotherapy. Methods: MET PET was prospectively performed in 36 patients with gliomas before and within one month after radiotherapy. Tumor MET uptake was measured with the semiquantitative tumor-to-nontumor ratio (T/N ratio). The MET uptake in the tumor and relevant clinical parameters were entered into univariate and multivariate survival analysis. Results: All tumors were identified in the baseline MET PET study. Patients with a baseline T/N ratio of < 4.0 had a significant better survival than patients with a baseline T/N ratio > 4.0 (2-year survival rate: 50.8% versus 0%, P=0.026). Patients with a post radiotherapy ratio of <4.0 had a better survival than that with a post radiotherapy ratio > 4.0 (2-year survival rate: 50.4% versus 0%, P=0.0012). The univariate analysis showed that both baseline and postradiotherapy T/N ratio were statistically significant predictors of patient survival, and postradiotherapy T/N ratio was a significant independent survival predictor in multivariate analysis. Tumors with larger T/N ratio had a significantly poorer prognosis. Conclusions: Baseline MET uptake was a potential survival indicator and postradiotherapy MET uptake was a significant independent predicator in glioma patients treated by radiotherapy. MET PET is a valuable tool in the predication of survival in patients with gliomas treated by radiotherapy.

No significant financial relationships to disclose.

C-type natriuretic peptide modulates glutamate receptors on cultured rat retinal amacrine cells

C-type natriuretic peptide, widely distributed in the CNS, may work as a neuromodulator. In this work, we investigated modulation by C-type natriuretic peptide of functional properties of glutamate receptors in rat retinal GABAergic amacrine cells in culture. Immunocytochemical data revealed that natriuretic peptide receptor-B was strongly expressed on the membrane of cultured GABAergic amacrine cells. By whole cell recording techniques we further identified the glutamate receptor expressed on the GABAergic amacrine cells as an AMPA-preferring subtype. Incubation with C-type natriuretic peptide suppressed the AMPA receptor-mediated current of these cells in a dose-dependent manner by decreasing the efficacy and apparent affinity for glutamate. The effect of C-type natriuretic peptide was reversed by HS-142-1, a guanylyl cyclase-coupled natriuretic peptide receptor-A/B antagonist. Meanwhile, the selective natriuretic peptide receptor-C agonist cANF did not change the glutamate current. In conjunction with the immunocytochemical data, these results suggest that the C-type natriuretic peptide effect may be mediated by natriuretic peptide receptor-B. Furthermore, incubation of retinal cultures in the C-type natriuretic peptide-containing medium elevated cGMP immunoreactivity in the GABAergic amacrine cells, and the C-type natriuretic peptide effect on the glutamate current was mimicked by application of 8-Br-cGMP. It is therefore concluded that C-type natriuretic peptide may modulate the glutamate current by increasing the intracellular concentration of cGMP in these cells via activation of natriuretic peptide receptor-B.

N-methyl-d-aspartate receptor-dependent long-term potentiation in CA1 region affects synaptic expression of glutamate receptor subunits and associated proteins in the whole hippocampus

Long term potentiation in hippocampus, evoked by high-frequency stimulation, is mediated by two major glutamate receptor subtypes, alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate receptors and N-methyl-D-aspartate receptors. Receptor subunit composition and its interaction with cytoplasmic proteins constitute different pathways regulating synaptic plasticity. Here, we provide further evidence that N-methyl-D-aspartate receptor-mediated long term potentiation evoked at hippocampal CA1 region of rats induced by high-frequency stimulation of the Schaffer collateral-commissural pathway in vivo is not dependent on N-methyl-D-aspartate receptor subunit NR2B. Applying semi-quantitative immunoblotting, we found that in the whole tetanized hippocampus, synaptic expression of the N-methyl-D-aspartate and alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate receptor subunits (NR1, NR2A, glutamate receptor 1) and their associated partners, e.g. synaptic associated protein 97, postsynaptic density protein 95, alpha subunit of Ca2+/calmodulin-dependent protein kinase II, neuronal nitricoxide synthase, increased 180 min post-high-frequency stimulation. Moreover, phosphorylation of Ca2+/calmodulin-dependent protein kinase II at thr286 and glutamate receptor 1 at ser831 was increased 30 min post-high-frequency stimulation and blocked by N-methyl-D-aspartate receptor antagonists (AP-5 and MK-801). In sham group and controls, these changes were not observed. The expression of several other synaptic proteins (NR2B, glutamate receptors 2/3, N-ethylmaleimide sensitive factor) was not affected by long term potentiation induction. In hippocampal homogenates, the level of these proteins remained unchanged. These data indicate that N-methyl-D-aspartate receptor-dependent long term potentiation in CA1 region in vivo mainly affects the synaptic expression of glutamate receptor subunits and associated proteins in the whole hippocampus. The alteration of molecular aspects can play a role in regulating the long-lasting synaptic modification in hippocampal long term potentiation in vivo.

Possible observation of phase separation near a quantum phase transition in doubly connected ultrathin superconducting cylinders of aluminum

The kinetic energy of superconducting electrons in an ultrathin, doubly connected superconducting cylinder, determined by the applied flux, increases as the cylinder diameter decreases, leading to a destructive regime around half-flux quanta and a superconductor to normal metal quantum phase transition (QPT). Regular steplike features in resistance versus temperature curves taken at fixed flux values were observed near the QPT in ultrathin Al cylinders. It is proposed that these features are most likely resulting from a phase separation near the QPT in which normal regions nucleate in a homogeneous superconducting cylinder.