Acute pharmacogenetic activation of medial prefrontal cortex excitatory neurons regulates anxiety-like behaviour

The medial prefrontal cortex (mPFC) is implicated in anxiety-like behaviour. In rodent models, perturbations of mPFC neuronal activity through pharmacological manipulations, optogenetic activation of mPFC neurons or cell-type specific pharmacogenetic inhibition of somatostatin interneurons indicate conflicting effects on anxiety-like behaviour. In the present study we examined the effects of pharmacogenetic activation of Ca²⁺/calmodulin-dependent protein kinase α (CamKIIα)-positive excitatory neurons on anxiety-like behaviour. We used clozapine-N-oxide (CNO) to pharmacogenetically activate virally delivered CamKIIα-hM3Dq-DREADD in mPFC excitatory neurons. The effects of acute CNO or vehicle treatment on anxiety-like behaviour in the open field and elevated plus maze tests were examined in rats virally infected with either CamKIIα-hM3Dq-DREADD or CamKIIα-GFP. In addition, the effects of acute CNO treatment on the expression of the neuronal activity marker c-Fos were examined in the mPFC as well as downstream target neuronal circuits using immunohistochemistry. Acute pharmacogenetic activation of mPFC excitatory neurons evoked a significant decrease in anxiety-like behaviour selectively on the elevated plus maze task, but not the open field test. Acute CNO treatment resulted in enhanced c-Fos-immunopositive cell number in the infralimbic, prelimbic and cingulate subdivisions of the mPFC. This was also accompanied by enhanced c-Fos-immunopositive cell number in multiple downstream circuits of the mPFC in CNO-treated hM3Dq animals. Acute pharmacogenetic activation of mPFC excitatory neurons reduces anxiety-like behaviour in a task-specific fashion accompanied by enhanced c-Fos expression in the mPFC and multiple target circuits implicated in the regulation of anxiety-like behaviour.     

Enhancing ligand–protein binding in affinity thermoprecipitation: Elucidation of spacer effects

Copolymers of N‐isopropylacrylamide and N‐acryloyl amino acid spacers of varying chain length were synthesized. p‐Aminobenzamidine (PABA) was chemically linked to the pendant carboxyl groups of these polymers to obtain thermoprecipitating affinity polymers. The inhibition constant (K_i) of these polymers for trypsin decreased, i.e., the efficiency of PABA–trypsin binding increased with increase in the spacer chain length. The polymer to which PABA was linked through a spacer of five methylene groups exhibited eleven times lower K_i than that of the polymer containing PABA without a spacer. Investigations on model inhibitors N‐acyl‐p‐aminobenzamidines showed that this enhancement in trypsin binding by the polymers was due to the spacer as well as to microenvironmental effects. Recovery and specific activity of the trypsin recovered increased with the spacer chain length. Separation of trypsin from a mixture of trypsin and chymotrypsin was also enhanced with the spacer chain length. The inhibition constants of these affinity polymers were not adversely affected by the crowding effect. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 418–425, 1999.     

Organic Matter Stimulates Bacteria and Arbuscular Mycorrhizal Fungi in Bauhinia purpurea and Leucaena diversifolia Plantations on Eroded Slopes in Nepal

Erosion resulting from landslides is a serious problem in mountainous countries such as Nepal. To restore such sites it is essential to establish plant cover that protects the soil and reduces surface erosion. Mycorrhizal fungi growing in symbiosis with plants are essential in this respect because they improve both plant nutrient uptake and soil structure. We investigated the influence of organic matter and P amendment on recently produced biomass of bacteria and arbuscular mycorrhizal (AM) fungi in eroded slopes in Nepal. Eroded soil mixed with different types of organic matter or P was placed in mesh bags, which were buried around trees of Bauhinia purpurea and Leucaena diversifolia between June 2003 and December 2003 (the wet season) or between December 2003 and June 2004 (the dry season). Signature fatty acids were used to determine bacterial and AM fungal biomass after the 6‐month intervals. The amount and composition of AM fungal spores were analyzed in the mesh bags from the dry season. More microbial biomass was produced during the wet season than during the dry season. Furthermore, organic matter addition enhanced the production of AM fungal and bacterial biomass during both periods. The positive influence of organic matter addition on AM fungi could be an important contribution to plant survival in plantations on eroded slopes. Different AM spore communities and bacterial profiles were obtained with different organic amendments and this suggests a possible way of selecting for specific microbial communities in the management of eroded sites.     

Metastasis suppressors genes in cancer

The major problem for cancer patients is metastasis of the cancer from the primary tumor to secondary sites. Metastasis is the process by which tumor cells disseminate from the primary tumor, migrate through the basement membrane, survive in the circulatory system, invade into a secondary site, and start to proliferate. In the past, research had concentrated on the biology, taking more of a global view instead of a molecular view. More recently, the focus has been determining the molecular underpinnings, looking at genes that induce or inhibit metastasis. Metastasis suppressors, by definition, inhibit metastasis at any step of the metastatic cascade without blocking primary tumor growth. The expanding list of metastasis suppressors exist with every cellular compartment and have been shown to work by regulating signaling pathways that inhibit proliferation, cell migration and growth at the secondary site. Still, the biochemical basis of their inhibition is not completely known. Here we review the known metastasis suppressors and summarize the suspected mechanisms by which they inhibit metastasis.     

Allergen Challenge Induces Ifng Dependent GTPases in the Lungs as Part of a Th1 Transcriptome Response in a Murine Model of Allergic Asthma

According to the current paradigm, allergic airway inflammation is mediated by Th2 cytokines and pro-inflammatory chemokines. Since allergic inflammation is self-limited, we hypothesized that allergen challenge simultaneously induces anti-inflammatory genes to counter-balance the effects of Th2 cytokines and chemokines. To identify these putative anti-inflammatory genes, we compared the gene expression profile in the lungs of ragweed-sensitized mice four hours after challenge with either PBS or ragweed extract (RWE) using a micro-array platform. Consistent with our hypothesis, RWE challenge concurrently upregulated Th1-associated early target genes of the Il12/Stat4 pathway, such as p47 and p65 GTPases (Iigp, Tgtp and Gbp1), Socs1, Cxcl9, Cxcl10 and Gadd45g with the Th2 genes Il4, Il5, Ccl2 and Ccl7. These Th1-associated genes remain upregulated longer than the Th2 genes. Augmentation of the local Th1 milieu by administration of Il12 or CpG prior to RWE challenge further upregulated these Th1 genes. Abolition of the Th1 response by disrupting the Ifng gene increased allergic airway inflammation and abrogated RWE challenge-induced upregulation of GTPases, Cxcl9, Cxcl10 and Socs1, but not Gadd45g. Our data demonstrate that allergen challenge induces two sets of Th1-associated genes in the lungs: 1) Ifng-dependent genes such as p47 and p65 GTPases, Socs1, Cxcl9 and Cxcl10 and 2) Ifng-independent Th1-inducing genes like Gadd45g. We propose that allergen-induced airway inflammation is regulated by simultaneous upregulation of Th1 and Th2 genes, and that persistent unopposed upregulation of Th1 genes resolves allergic inflammation.     

Mathematical modelling of radiotherapy strategies for early breast cancer

Targeted intraoperative radiotherapy (Targit) is a new concept of partial breast irradiation where single fraction radiotherapy is delivered directly to the tumour bed. Apart from logistic advantages, this strategy minimizes the risk of missing the tumour bed and avoids delay between surgery and radiotherapy. It is presently being compared with the standard fractionated external beam radiotherapy (EBRT) in randomized trials. In this paper we present a mathematical model for the growth and invasion of a solid tumour into a domain of tissue (in this case breast tissue), and then a model for surgery and radiation treatment of this tumour. We use the established linear-quadratic (LQ) model to compute the survival probabilities for both tumour cells and irradiated breast tissue and then simulate the effects of conventional EBRT and Targit. True local recurrence of the tumour could arise either from stray tumour cells, or the tumour bed that harbours morphologically normal cells having a predisposition to genetic changes, such as a loss of heterozygosity (LOH) in genes that are crucial for tumourigenesis, e.g. tumour suppressor genes (TSGs). Our mathematical model predicts that the single high dose of radiotherapy delivered by Targit would result in eliminating all these sources of recurrence, whereas the fractionated EBRT would eliminate stray tumour cells, but allow (by virtue of its very schedule) the cells with LOH in TSGs or cell-cycle checkpoint genes to pass on low-dose radiation-induced DNA damage and consequently mutations that may favour the development of a new tumour. The mathematical model presented here is an initial attempt to model a biologically complex phenomenon that has until now received little attention in the literature and provides a 'proof of principle' that it is possible to produce clinically testable hypotheses on the effects of different approaches of radiotherapy for breast cancer.     

Diagonally Aligned Squared Metal Nano-pillar with Increased Hotspot Density as a Highly Reproducible SERS Substrate

Metal nanostructure on dielectric substrate with increased hotspot density has drawn considerable research interest in recent years toward the study of surface-enhanced Raman spectroscopy (SERS). In this paper, we report the fabrication of a diagonally aligned squared metal nano-pillar (SMNP) on a dielectric substrate and revealed it as an efficient SERS substrate with increased hotspot density for sensing of Raman active materials. Due to dipolar coupling and lightening rod effect between the neighboring nano-pillars, the localized surface plasmon resonance (LSPR) field intensity increased significantly in the space between two neighboring SMNP which would lead to the enhancement of SERS signal. The SMNP has been fabricated using electron beam lithographic (EBL) technique with hotspot density of 2.45 × 10⁷/mm². With the designed SERS substrate an average enhancement factor (EF) of 3.27 × 10⁸ has been observed with relative standard deviation of ～13 %.