Y-like retinal ganglion cells innervate the dorsal raphe nucleus in the Mongolian gerbil (Meriones unguiculatus)

Background

The dorsal raphe nucleus (DRN) of the mesencephalon is a complex multi-functional and multi-transmitter nucleus involved in a wide range of behavioral and physiological processes. The DRN receives a direct input from the retina. However little is known regarding the type of retinal ganglion cell (RGC) that innervates the DRN. We examined morphological characteristics and physiological properties of these DRN projecting ganglion cells.

Methodology/Principal Findings

The Mongolian gerbils are highly visual rodents with a diurnal/crepuscular activity rhythm. It has been widely used as experimental animals of various studies including seasonal affective disorders and depression. Young adult gerbils were used in the present study. DRN-projecting RGCs were identified following retrograde tracer injection into the DRN, characterized physiologically by extracellular recording and morphologically after intracellular filling. The result shows that DRN-projecting RGCs exhibit morphological characteristics typical of alpha RGCs and physiological response properties of Y-cells. Melanopsin was not detected in these RGCs and they show no evidence of intrinsic photosensitivity.

Conclusions/Significance

These findings suggest that RGCs with alpha-like morphology and Y-like physiology appear to perform a non-imaging forming function and thus may participate in the modulation of DRN activity which includes regulation of sleep and mood.     

Use of the D-R model to define trends in the emergence of Ceftazidime-resistant Escherichia coli in China

Objective

To assess the efficacy of the D-R model for defining trends in the appearance of Ceftazidime-resistant Escherichia coli.

Methods

Actual data related to the manifestation of Ceftazidime-resistant E. coli spanning years 1996–2009 were collected from the China National Knowledge Internet. These data originated from 430 publications encompassing 1004 citations of resistance. The GM(1,1) and the novel D-R models were used to fit current data and from this, predict trends in the appearance of the drug-resistant phenotype. The results were evaluated by Relative Standard Error (RSE), Mean Absolute Deviation (MAD) and Mean Absolute Error (MAE).

Results

Results from the D-R model showed a rapid increase in the appearance of Ceftazidime-resistant E. coli in this region of the world. These results were considered accurate based upon the minor values calculated for RSE, MAD and MAE, and were equivalent to or better than those generated by the GM(1,1) model.

Conclusion

The D-R model which was originally created to define trends in the transmission of swine viral diseases can be adapted to evaluating trends in the appearance of Ceftazidime-resistant E. coli. Using only a limited amount of data to initiate the study, our predictions closely mirrored the changes in drug resistance rates which showed a steady increase through 2005, a decrease between 2005 and 2008, and a dramatic inflection point and abrupt increase beginning in 2008. This is consistent with a resistance profile where changes in drug intervention temporarily delayed the upward trend in the appearance of the resistant phenotype; however, resistance quickly resumed its upward momentum in 2008 and this change was better predicted using the D-R model. Additional work is needed to determine if this pattern of “increase-control-increase” is indicative of Ceftazidime-resistant E. coli or can be generally ascribed to bacteria acquiring resistance to drugs in the absence of alternative intervention.     

Expression of soluble, biologically active recombinant human endostatin in Escherichia coli

Endostatin, a 20kDa C-terminal fragment of collagen XVIII, is a potent anti-angiogenic protein and inhibitor of tumor growth. Recombinant endostatin was prepared from Escherichia coli deposited as insoluble, inactive inclusion bodies. In the present study, we produced soluble and biologically active recombinant human endostatin (rhEndostatin) in E. coli by employing both co-expression of the molecular chaperones and lower temperature fermentation. Two groups of chaperones Trigger factor and GroEL-GroES (GroEL/ES), DnaK-DnaJ-GrpE and GroEL/ES, were co-expressed, respectively, with rhEndostatin at different temperatures (37, 25, and 16 degrees C). It revealed that low temperature or molecular chaperones alone could enhance the production of active rhEndostatin; meanwhile, combinational employment of low temperature cultivation (16 degrees C) together with co-expression of DnaK-DnaJ-GrpE and GroEL/ES was more effective to prevent aggregation of rhEndostatin. The production of soluble rhEndostatin was about 36 mg/L, and at least 16 mg of rhEndostatin was purified from 1L flask culture. The purified rhEndostatin specifically inhibited the proliferation of endothelial cell-bovine capillary endothelial cell in a dose-dependent manner, and it showed potent anti-angiogenic capability on the chorioallantoic membrane of chick embryo in vivo. Our study provides a feasible and convenient approach to produce soluble and biologically active rhEndostatin.     

Multivalent interactions of calcium/calmodulin-dependent protein kinase II with the postsynaptic density proteins NR2B, densin-180, and alpha-actinin-2

Dendritic calcium/calmodulin-dependent protein kinase II (CaMKII) is dynamically targeted to the synapse. We show that CaMKIIalpha is associated with the CaMKII-binding proteins densin-180, the N-methyl-D-aspartate receptor NR2B subunit, and alpha-actinin in postsynaptic density-enriched rat brain fractions. Residues 819-894 within the C-terminal domain of alpha-actinin-2 constitute the minimal CaMKII-binding domain. Similar amounts of Thr286-autophosphorylated CaMKIIalpha holoenzyme [P-T286]CaMKII bind to alpha-actinin-2 as bind to NR2B (residues 1260-1339) or to densin-180 (residues 1247-1495) in glutathione-agarose cosedimentation assays, even though the CaMKII-binding domains share no amino acid sequence similarity. Like NR2B, alpha-actinin-2 binds to representative splice variants of each CaMKII gene (alpha, beta, gamma, and delta), whereas densin-180 binds selectively to CaMKIIalpha. In addition, C-terminal truncated CaMKIIalpha monomers can interact with NR2B and alpha-actinin-2, but not with densin-180. Soluble alpha-actinin-2 does not compete for [P-T286]CaMKII binding to immobilized densin-180 or NR2B. However, soluble densin-180, but not soluble NR2B, increases CaMKII binding to immobilized alpha-actinin-2 by approximately 10-fold in a PDZ domain-dependent manner. A His6-tagged NR2B fragment associates with GST-densin or GST-actinin but only in the presence of [P-T286]CaMKII. Similarly, His6-tagged densin-180 or alpha-actinin fragments associate with GST-NR2B in a [P-T286]CaMKII-dependent manner. In addition, GST-NR2B and His6-tagged alpha-actinin can bind simultaneously to monomeric CaMKII subunits. In combination, these data support a model in which [P-T286]CaMKIIalpha can simultaneously interact with multiple dendritic spine proteins, possibly stabilizing the synaptic localization of CaMKII and/or nucleating a multiprotein synaptic signaling complex.     

Screening assays for cholinesterases resistant to inhibition by organophosphorus toxicants

Methods to measure resistance to inhibition by organophosphorus toxicants (OP) for mutants of butyrylcholinesterase (EC 3.1.1.8; BChE) and acetylcholinesterase (EC 3.1.1.7; AChE) enzymes were devised. Wild-type cholinesterases were completely inhibited by 0.1 mM echothiophate or 0.001 mM diisopropylfluorophosphate, but human BChE mutants G117H, G117D, L286H, and W231H and snake AChE mutant HFQT retained activity. Tissues containing a mixture of cholinesterases could be assayed for amount of G117H BChE. For example, the serum of transgenic mice expressing human G117H BChE contained 0.5 microg/ml human G117H BChE, 2 microg/ml wild-type mouse BChE, and 0.06 microg/ml wild-type mouse AChE. The oligomeric structure of G117H BChE in the serum of transgenic mice was determined by nondenaturing gel electrophoresis followed by staining for butyrylthiocholine hydrolysis activity in the presence of 0.1 mM echothiophate. Greater than 95% of the human G117H BChE in transgenic mouse serum was a tetramer. To visualize the distribution of G117H BChE in tissues of transgenic mice, sections of small intestine were treated with echothiophate and then stained for BChE activity. Both wild-type and G117H BChE were in the epithelial cells of the villi. These assays can be used to identify OP-resistant cholinesterases in culture medium and in animal tissues.     

广东象头山国家级自然保护区珍稀野生花卉资源

对广东象头山国家级自然保护区珍稀野生花卉资源调查结果表明,本区内有52科68属88种,其中蕨类植物11科11属13种;被子植物41科57属75种,并对其基本组成、多样性等进行分析。根据本区珍稀野生花卉的现状与特点,划分出生活类型,提出园林配置方式,对资源保护和开发利用提出建议。     

Prolonged blockade of VEGF receptors does not damage retinal photoreceptors or ganglion cells

It has recently been reported that relatively short‐term inhibition of vascular endothelial growth factor (VEGF) signaling can cause photoreceptor cell death, a potentially clinically important finding since VEGF blockade has become an important modality of treatment of ocular neovascularization and macular edema. However, in a set of studies in which we achieved extended and complete blockage of VEGF‐induced vascular leakage through retinal expression of a VEGF binding protein, we did not observe any toxicity to retinal neurons. To follow‐up on these apparently discrepant findings, we designed a set of experiments with the kinase inhibitor SU4312, which blocks phosphorylation of VEGF receptors, to look directly for evidence of VEGF inhibition‐related retinal toxicity. Using transgenic mice with sustained expression of VEGF in photoreceptors, we determined that periocular injection of 3 µg of SU4312 every 5 days markedly suppressed subretinal neovascularization, indicating effective blockade of VEGF signaling. Wild‐type mice given periocular injections of 5 µg of SU4312 every 5 days for up to 12 weeks showed normal scotopic and photopic electroretinograms (ERGs), no TUNEL stained cells in the retina, and no reduction in outer nuclear layer thickness. Incubation of cultured ganglion cells or retinal cultures containing photoreceptors with high doses of SU4312 did not reduce cell viability. These data suggest that blocking VEGF signaling in the retina for up to 12 weeks does not damage photoreceptors nor alter ERG function and should reassure patients who are receiving frequent injections of VEGF antagonists for choroidal and retinal vascular diseases. J. Cell. Physiol. 224:262–272, 2010 © 2010 Wiley‐Liss, Inc.     

Freeze-drying of ATP entrapped in cationic,low lipid liposomes

Concerning the instability of ATP liposomes formulated to easily diffuse through the liver (size ～100 nm), this work targets the key parameters that influence the freeze-drying of a preparation that combines cholesterol, DOTAP and phosphatidylcholine (either natural soybean or egg (SPC or EPC) or hydrogenated (HSPC)). After freeze-drying blank liposomes, size increased significantly when initial lipid concentration was lowered from 20 to 5 mM (p = 0.0018). With low lipid concentration preparation (5 mM), SPC limited size increase (SI) more efficiently compared to EPC or HSPC. With SPC and EPC, sucrose showed better size results compared to trehalose (Lyoprotectant/Lipid ratio (w/w) avoiding any SI: ～5 and ～10 (for SPC), ～10 and ～15 (for EPC), for sucrose and trehalose, respectively), but the opposite was evidenced with HSPC liposomes where a Trehalose/Lipid ratio of 25 barely prevented SI. In addition, slow versus quick cooling rate led to limiting SI for HSPC liposomes (p = 0.0035). With sucrose or trehalose at both Lyoprotectant/Lipid ratios ensuring size stabilisation (10:1 and 15:1, respectively), ATP leakage ranged between 38.8 ± 7.9% and 58.2 ± 1.4%. In conclusion, this study emphasizes that using strict size maintenance as the primary objective does not result in drug complete retention inside the liposome core.