In silico analysis and experimental validation of active compounds from fructus Schisandrae chinensis in protection from hepatic injury

OBJECTIVES

The aim of this study was to explore mechanisms by which fructus Schisandrae chinensis (Wuweizi) is able to reveal its protective capacity against hepatocyte injury.

MATERIALS AND METHODS

Identification of candidate small molecular compounds was performed by text-mining, extraction and isolation, reverse-docking, network construction, molecular docking and molecular dynamics (MD) simulation. In vitro cytological examination and western blotting were used to validate efficacy of selected compounds.

RESULTS

We analyzed chemical composition of fructus Schisandrae chinensis and constructed protein-protein networks of key targets. Networks of miRNA-protein were constructed. Molecular docking and MD simulation results supported good interaction between selected compound 11/12 and GBA3/SHBG. Further in vitro examination divulged molecular mechanisms involved.

CONCLUSIONS

In silico analysis and experimental validation together demonstrated that compound 11/12 of fructus Schisandrae chinensis targetted GBA3/SHBG in hepatocytes. Hopefully this will shed light on exploration of its complex molecular mechanisms.

A Randomised Controlled Trial to Evaluate the Effectiveness of Intrathecal Bupivacaine Combined with Different Adjuvants (Fentanyl, Clonidine and Dexmedetomidine) in Caesarean Section

PURPOSE

The purpose of this study was to evaluate comparatively, in women undergoing caesarean section under spinal anesthesia, the effectiveness of hyperbaric bupivacaine combined with 3 different adjuvants (fentanyl, clonidine, and dexmedtomidine) on quality of blockade and maternal and neonatal repercussions.

METHOD

84 patients undergoing elective surgeries under spinal anesthesia were randomized into 4 groups of 21 each, gB, gBF, gBC and gBD. Patients in groups gb, gBF, gBC and gBD were given bupivacaine alone, bupivacaine plus fentanyl (15.0 µg), bupivacaine plus fentanyl plus clonidine (75 µg), and bupivacaine plus dexmedetomidine (10 µg), respectively. Hemodynamic parameters evaluated were the onset and level of sensory block, perioperative analgesia, degree and recovery time of motor block, duration of analgesia, sedation, and maternal-foetal repercussions.

RESULTS

The onset of blockade was significantly faster in groups with adjuvants clonidine and dexmedetomidine compared with gB and gBF. Patients in Groups gB and gBF reported pain during the perioperative period. Duration of analgesia was significantly higher in Group gBD and was comparable to gBC and time to motor block recovery was significantly higher in Group gBD. Sedation was significant in Group gBD and gBC.

CONCLUSION

Addition of dexmedetomidine and clonidine as adjuvants to hyperbaric bupivacaine provided adequate anesthesia and postoperative analgesia compared to fentanyl adjuvant without causing any significant side effects.

Plant lectins, from ancient sugar-binding proteins to emerging anti-cancer drugs in apoptosis and autophagy

Ubiquitously distributed in different plant species, plant lectins are highly diverse carbohydrate-binding proteins of non-immune origin. They have interesting pharmacological activities and currently are of great interest to thousands of people working on biomedical research in cancer-related problems. It has been widely accepted that plant lectins affect both apoptosis and autophagy by modulating representative signalling pathways involved in Bcl-2 family, caspase family, p53, PI3K/Akt, ERK, BNIP3, Ras-Raf and ATG families, in cancer. Plant lectins may have a role as potential new anti-tumour agents in cancer drug discovery. Thus, here we summarize these findings on pathway- involved plant lectins, to provide a comprehensive perspective for further elucidating their potential role as novel anti-cancer drugs, with respect to both apoptosis and autophagy in cancer pathogenesis, and future therapy.

Key autophagic targets and relevant small-molecule compounds in cancer therapy

Autophagy is a highly conserved lysosomal degradation process which can recycle unnecessary or dysfunctional cell organelles and proteins, thereby playing a crucial regulatory role in cell survival and maintenance. It has been widely accepted that autophagy regulates various pathological processes, among which cancer attracts much attention. Autophagy may either promote cancer cell survival by providing energy during unfavourable metabolic circumstance or can induce individual cancer cell death by preventing necrosis and increasing genetic instability. Thus, dual roles of autophagy may determine the destiny of cancer cells and make it an attractive target for small-molecule drug discovery. Collectively, key autophagy-related elements as potential targets, oncogenes mTORC1, class I PI3K and AKT, as well as tumour suppressor class III PI3K, Beclin-1 and p53, have been discussed. In addition, some small molecule drugs, such as rapamycin and its derivatives, rottlerin, PP242 and AZD8055 (targeting PI3K/AKT/mTORC1), spautin-1, and tamoxifen, as well as oridonin and metformin (targeting p53), can modulate autophagic pathways in different types of cancer. All these data will shed new light on targeting the autophagic process for cancer therapy, using small-molecule compounds, to fight cancer in the near future.

Association of IL-1, IL-18, and IL-33 gene polymorphisms with late-onset Alzheimer׳s disease in a Hunan Han Chinese population

Interleukin (IL)-1 plays an important role in Alzheimer׳s disease (AD), and single nucleotide polymorphisms (SNPs) in the IL-1 gene have been shown to be associated with AD susceptibility. IL-18 and IL-33 are proinflammatory cytokines of the IL-1 family, and increasing evidence has accumulated to support their crucial role in AD pathogenesis. To examine whether SNPs in IL-1α (rs1800587), IL-1β (rs1143627), IL-18 (rs187238), and IL-33 (rs11792633) are associated with late-onset Alzheimer׳s disease (LOAD) in a Hunan Han Chinese population, we carried out a case-control study involving 201 LOAD patients and 257 healthy controls. No significant differences were found in genotype frequencies of rs1800587 between LOAD patients and controls (P=0.079), but the T allele of rs1800587 was associated with a significantly increased risk of LOAD (P=0.032, odds ratio (OR)=1.592). Significant differences in genotype (P=0.004) and allele (P=0.001) frequencies of rs11792633 were found between LOAD patients and controls, but not for rs1143627 (P=0.535, 0.262, respectively) or rs187238 (P=0.257, 0.139, respectively). The T allele of rs11792633 was found to be a protective factor for LOAD (OR=0.648). These findings suggest that the IL-1α SNP rs1800587 and IL-33 SNP rs11792633, but not the IL-1β SNP rs1143627 or the IL-18 SNP rs187238, contribute to LOAD susceptibility in the Hunan Han Chinese population. This article is part of a Special Issue entitled SI: Brain and Memory.

PUMA is invovled in ischemia/reperfusion-induced apoptosis of mouse cerebral astrocytes

PUMA (p53-upregulated modulator of apoptosis), a BH3-only member of the Bcl-2 protein family, is required for p53-dependent and p53-independent forms of apoptosis. PUMA has been invovled in the onset and progress of several diseases, including cancer, acquired immunodeficiency syndrome, and ischemic brain disease. Although many studies have shown that ischemia and reperfusion (I/R) can induce the apoptosis of astrocytes, the role of PUMA in I/R-mediated apoptosis of cerebral astrocyte apoptosis remains unclear. To mimic in vivo I/R conditions, primary mouse cerebral astrocytes were incubated in a combinational cultural condition of oxygen, glucose, and serum deprivation (OSGD) for 1 h followed by reperfusion (OSGD/R). Cell death determination assays and cell viability assays indicated that OSGD and OSGD/R induce the apoptosis of primary cerebral astrocytes. The expression of PUMA was significantly elevated in primary cerebral astrocytes during OSGD/R. Moreover, targeted down-regulation of PUMA by siRNA transfection significantly decreased the OSGD/R-induced apoptosis of primary cerebral astrocytes. We also found that OSGD and OSGD/R triggered the release of cytochrome c in astrocytes, indicating the dependence on a mitochondrial apoptotic pathway. Reactive oxygen species (ROS) was extremely generated during OSGD and OSGD/R, and the elimination of ROS by treated with N-acetyl-L-cysteine (NAC) remarkably inhibited the expression of PUMA and the apoptosis of primary cerebral astrocytes. The activation of Caspase 3 and Caspase 9 was extremely elevated in primary cerebral astrocytes during OSGD. In addition, we found that knockdown of PUMA led to the depressed expression of Bax, cleaved caspase-9 and caspase-3 during OSGD/R. These results indicate that PUMA is invovled in the apoptosis of cerebral astrocytes upon I/R injury.

UNC51-like kinase 1, autophagic regulator and cancer therapeutic target

Autophagy, the cell process of self-digestion, plays a pivotal role in maintaining energy homoeostasis and protein synthesis. When required, it causes degradation of long-lived proteins and damaged organelles, indicating that it may play a dual role in cancer, by both protecting against and promoting cell death. The autophagy-related gene (Atg) family, with more than 35 members, regulates multiple stages of the process. Serine/threonine protein kinase Atg1 in yeast, for example, can interact with other ATG gene products, functioning in autophagosome formation. One mammalian homologue of Atg1, UNC-51-like kinase 1 (ULK1) and its related complex ULK1-mAtg13-FIP200 can mediate autophagy under nutrient-deprived conditions, by protein-protein interactions and post-translational modifications. Although specific mechanisms of how ULK1 and its complex transduces upstream signals to the downstream central autophagy pathways is not fully understood, past studies have indicated that ULK1 can both suppress and promote tumour growth under different conditions. Here, we summarize some properties of ULK1 which can regulate autophagy in cancer, which may shed new light on future cancer therapy strategies, utilizing ULK1 as a potential new target.

(18)O(2) label mechanism of sulfur generation and characterization in properties over mesoporous Sm-based sorbents for hot coal gas desulfurization

Using a sol-gel method, SmMeOx/MCM-41 or SBA-15 (Me=Fe, Co and Zn) and corresponding unsupported sorbents were prepared. The desulfurization performance of these sorbents was evaluated over a fixed-bed reactor and the effects of reaction temperature, feed and sorbent composition on desulfurization performance were studied. Samarium-based sorbents used to remove H2S from hot coal gas were reported for the first time. The results of successive sulfidation/regeneration cycles revealed that SmFeO3/SBA-15 sorbent was suitable for desulfurization of hot coal gas in the chemical industry. The formation of elemental sulfur during both sulfidation and regeneration processes depended strongly on the catalytic action of Sm2O2S species, which was confirmed for the first time via high sensitive time of flight mass spectrometer (TOF-MS) using 6%vol(18)O2/Ar regeneration gas and can reduce markedly procedural complexity. The sorbents were characterized using N2-adsorption, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), temperature-programmed reduction of H2 (H2-TPR), thermogravimetry (TG) and time-of-flight mass spectrometry (TOF-MS) techniques.

cDNA-AFLP transcriptional profiling reveals genes expressed during flower development in Oncidium Milliongolds

The flower developmental process, which is crucial to the whole lifecycle of higher plants, is influenced by both environmental and endogenous factors. The genus Oncidium is commercially important for cut flower and houseplant industry and is ideal for flower development studies. Using cDNA-amplified restriction fragment length polymorphism analysis, we profiled transcripts that are differentially expressed during flower development of Oncidium Milliongolds. A total of 15,960 transcript-derived fragments were generated, with 114 primer sets. Of these, 1248 were sequenced, producing 993 readable sequences. BLASTX/N analysis showed that 833 of the 993 transcripts showed homology to genes in the NCBI databases, exhibiting functions involved in various processes, such as signal transduction, energy conversion, metabolism, and gene expression regulation. The full-length mRNAs of SUCROSE SYNTHASE 1 (SUS1) and LEAFY (LFY) were cloned, and their expression patterns were characterized. The results showed that the expression levels of SUS1 and LFY were similar during flower development. To confirm the function of SUS1 in flower buds, carbohydrate content and sucrose synthase activity were determined. The results showed that changes in sucrose content and sucrose synthase activity reflected SUS1 expression levels. Collectively, these results indicate that SUS1 influences flower development by regulating LFY expression levels through changing the sucrose content of flower buds.

Anti-CD11c antibody, Efalizumab attenuate ventilator-induced lung injury

BACKGROUND

The pathophysiology of ventilator-induced lung injury (VILI) involves multiple mechanisms including inflammation and inflammatory cells infiltration. The anti-CD11c monoclonal antibody, Efalizumab has been demonstrated to inhibit the T cell activation, migration and adhesion to keratinocytes.

MATERIALS AND METHODS

In this study, we induced lung injury with mechanical ventilation in male Sprague-Dawley rats, the rats were divided into four groups: lung-protective ventilation (LV), injurious ventilation (HV), HV+human IgG control and HV+ Efalizumab groups. Then we detected the lung tissue wet/dry ratio, and the activity of myeloperoxidase (MPO) was determined. The concentration of protein, TNF-a, IL-6, IL-1b and MIP-2 in the BALF were detected by ELISA. The expression ICAM-1 was measured by Realtime PCR.

RESULTS

Compared with the human IgG control treated group, the treatment of Efalizumab attenuate the ventilator-induced lung injury, including the wet/dry ratio and the activity of myeloperoxidase (MPO), meanwhile, the level of pro-inflammatory cytokines, such as TNF-a, IL-6, IL-1b and MIP-2 were decreased in the BALF of Efalizumab-treated group rats compared with the human IgG-treated control group. In addition, the histopathological index of ventilator-induced lung injury was improved after efalizumab treatment, that also reduced the recruitment of inflammatory cells into the lung, such as neutrophils.

CONCLUSIONS

Our data suggested that Efalizumab could protect rat from ventilator-induced lung injury and improve the survival time through the inhibition of intrapulmonary inflammatory response.

Effect of aminoguanidine intervention on neutrophils in diabetes inflammatory cells wound healing

To explore aminoguanidine (AG) effect on neutrophil functions and associated signal transduction way in diabetic rats wound healing. Sprague-Dawley (SD) rats were divided into 3 groups, Group A (control+burns), Group B (diabetes+burns), Group C (diabetes+burns+AG). Wound skin tissue was harvested at 6h, 24h and 36h after trauma, and then immunohistochemistry was used to detect AGE (advanced glycation end products) contents and RAGE (receptor of AGE) expression. Western blotting was applied to detect RAGE and NF-κB. Oxidative stress changes were detected by colorimetry. Inflammatory cytokines were determined by ELIASA and cell apoptosis by TUNEL. Pathological changes were analyzed by hematoxylin-eosin (HE) staining. In the wound tissue of Group C, compared to that in Group B, AGE content, RAGE expression level, NF-κB level declined, and MPO (myeloperoxidase) decreased at 36h; TNFα, IL-8, H2O2, GSH-Px (Glutathione peroxidse), and MDA (malondialdehyde) levels increased; dense post-traumatic inflammation belt formed obviously. AG for prophylactic use can promote the migration and respiratory burst of neutrophils markedly, and help to restore the functions of neutrophil; and the abnormal secretion of inflammation cytokines can be corrected partly. Blocking AGE deposition and promoting microenvironment were effective ways for diabetic wound healing.

Catalytic conversion of acetylene to polycyclic aromatic hydrocarbons over particles of pyroxene and alumina

Polycyclic aromatic hydrocarbons (PAHs) are known to be present in many astrophysical objects and environments, but our understanding of their formation mechanism(s) is far from satisfactory. In this paper, we describe an investigation of the catalytic conversion reaction of acetylene gas to PAHs over pyroxene and alumina. Crystalline silicates such as pyroxenes (with general formula [Mg, Fe]SiO₃) and alumina (Al₂O₃) are observed astrophysically through their infrared spectra and are likely to promote grain surface chemical reactions. In the experiments reported here, gas-phase PAHs were produced by the catalytic reaction of acetylene over crystalline silicates and alumina using a pulsed jet expansion technique and the gaseous products detected using time-of-flight mass spectrometry. In a separate experiment, the catalytic formation of PAHs from acetylene was further confirmed with acetylene gas at atmospheric pressure flowing continuously through a fixed-bed reactor. The gas effluent and carbonaceous compounds deposited on the catalysts were dissolved separately in dichloromethane and analysed using gas chromatography-mass spectrometry. Among the samples studied, alumina showed higher activity than the pyroxene-type grains for the acetylene reaction. It is proposed that formation of the PAHs relies on the Mg²⁺ ions in the pyroxenes and Al³⁺ ions in alumina, where these ions act as Lewis acid sites. X-ray diffraction, Fourier transform infrared and high-resolution transmission electron microscopy techniques were used to characterize the structure and physical properties of the pyroxene and alumina samples.

Development and validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous determination of acrivastine and pseudoephedrine in human plasma and its application in pharmacokinetics

A specific, sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the simultaneous determination of acrivastine and pseudoephedrine in human plasma samples. Plasma samples were processed and analyzed on a Phenomenex Luna 3 μ CN 100A column (150 mm×2.0 mm) eluted with the mobile phase consisting of methanol and 0.01 mol/L ammonium acetate water solution containing 0.1% formic acid (45:55, v/v) at a flow rate of 0.2 mL/min. The analytes were detected by positive ion electrospray ionization in multiple reaction monitoring mode. The transitions of m/z 349→278, m/z 166→148 and m/z 256→167 were monitored for acrivastine, pseudoephedrine and diphenhydramine (IS), respectively. The method was specific and sensitive with a lower limit of quantitation (LLOQ) of 1.52 ng/mL for acrivastine and 8.13 ng/mL for pseudoephedrine. The method showed good linearity in the range of 1.52~606.0 0 ng/mL for acrivastine and 8.13~813.12 ng/mL for pseudoephedrine (r≥0.996). The mean recovery were ranged 91.82% ~ 98.46% for acrivastine and 90.77% ~ 92.05% for pseudoephedrine. Validation results, such as accuracy, precision and repeatability were within the required limits. The method was successfully applied in a pharmacokinetic study of the acrivastine and pseudoephedrine hydrochloride compound capsule in humans.

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

1523

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.