Multiple target-based pharmacophore design from active site structures

Health care systems have benefitted from rational drug discovery processes like vHTS, virtual high throughput screening pharmacophores and quantitative structure-activity relationships, and many challenges have been explored using such techniques: decisions on specificity and selectivity are made after screening millions of molecules for multiple targets. Recent challenges in drug research emphasize the design of drugs that bind with more than one target of interest (multi-target) and do not bind with undesirable targets. This work attempts to use a three-dimensional interaction profile of the active site of a class of proteins, identify selective positions for the binding of functional groups, called features, and develop ensembles of multi-targeted pharmacophores that retain specificity and selectivity. The goal of this study is to develop multi-target pharmacophores by computational methods using protein structures alone to guide the discovery of novel inhibitors of plasmepsins, displaying selectivity over their human homologs, cathepsin D and pepsin. The development of such novel tools is attempted using a combination of different approaches such as the molecular interaction field, clique graph and inductive logic programming to identify and compare specific and selective complementary features. The identification of selective combinations of features has resulted in the design of multi-featured specific and selective pharmacophores that are validated using antimalarial compounds in ChEMBL that are known for their anti-plasmepsin II activity. This novel method is computationally less intensive and is applicable to any known class of target structures for finding specific and selective binders simultaneously.

meso-Aryl [20]π Homoporphyrin: The Simplest Expanded Porphyrin with the Smallest Möbius Topology

An unstable conjugated homoporphyrin was successfully stabilized by introducing meso-aryl substitutents. It was evident from the moderate diatropic ring current found by NMR analysis that the newly formed 20π conjugated free base and its protonated form exhibited Möbius aromatic character. Furthermore, complexation as a ligand with an Rh^I ion afforded a unique binding mode and retained the Möbius aromaticity. Overall, these compounds are the smallest Möbius aromatic molecules, as confirmed by spectral and crystal-structure analysis and supported by theoretical studies.

Mechanisms for Strong Anisotropy of In-Plane g-Factors in Hole Based Quantum Point Contacts

In-plane hole g factors measured in quantum point contacts based on p-type heterostructures strongly depend on the orientation of the magnetic field with respect to the electric current. This effect, first reported a decade ago and confirmed in a number of publications, has remained an open problem. In this work, we present systematic experimental studies to disentangle different mechanisms contributing to the effect and develop the theory which describes it successfully. We show that there is a new mechanism for the anisotropy related to the existence of an additional B_{+}k_{-}^{4}σ_{+} effective Zeeman interaction for holes, which is kinematically different from the standard single Zeeman term B_{-}k_{-}^{2}σ_{+} considered until now.

Yield of Image-Guided Needle Biopsy for Infectious Discitis: A Systematic Review and Meta-Analysis

BACKGROUND

Image-guided biopsy is routinely conducted in patients with suspected discitis, though the sensitivity reported in the literature ranges widely.

PURPOSE

We applied a systematic review and meta-analysis to estimate the yield of image-guided biopsy for infectious discitis.

DATA SOURCES

We performed a literature search of 4 data bases: PubMed, Cochrane CENTRAL Register of Controlled Trials, Embase.com, and Scopus from data base inception to March 2016.

STUDY SELECTION

A screen of 1814 articles identified 88 potentially relevant articles. Data were extracted for 33 articles, which were eligible if they were peer-reviewed publications of patients with clinical suspicion of discitis who underwent image-guided biopsy.

DATA ANALYSIS

Patients with positive cultures out of total image-guided biopsy procedures were pooled to estimate yield with 95% confidence intervals. Hypothesis testing was performed with an inverse variance method after logit transformation.

DATA SYNTHESIS

Image-guided biopsy has a yield of approximately 48% (793/1763), which is significantly lower than the open surgical biopsy yield of 76% (152/201; P < .01). Biopsy in patients with prior antibiotic exposure had a yield of 32% (106/346), which was not significantly different from the yield of 43% (336/813; P = .08) in patients without prior antibiotic exposure.

LIMITATIONS

The conclusions of this meta-analysis are primarily limited by the heterogeneity of the included studies.

CONCLUSIONS

Image-guided biopsy has a moderate yield for the diagnosis of infectious discitis, which is significantly lower than the yield of open surgical biopsy. This yield is not significantly affected by prior antibiotic use.

Impact of providing patients with copies of their medical correspondence: a randomised controlled study

BACKGROUND

In Australia, correspondence is routinely sent to general practitioners following a specialist consultation. Written communication is an important way to enhance patient experiences and understanding, yet most patients do not receive copies of their medical correspondence.

AIMS

To determine whether providing clinic correspondence and endoscopy reports to patients leads to improved understanding, satisfaction or anxiety.

METHODS

This is a prospective, randomised controlled study conducted at an Australian tertiary hospital from October 2013 to February 2015. New adult referrals to the general gastroenterology clinic requiring an urgent endoscopic procedure were eligible for the study. The intervention group received a copy of their clinic correspondence and endoscopy report, while the control group received neither. Participants completed questionnaires, including visual analogue scales and the Hospital Anxiety and Depression Scale, at three time points. Primary outcomes were patient understanding, anxiety and satisfaction.

RESULTS

A total of 70 participants was included in the study. There was no reduction in anxiety levels (P = 0.52), no increase in understanding (P = 0.73) or any increase in satisfaction (P = 0.33) in participants receiving correspondence. However, 97% of participants indicated that they wished to receive correspondence in the future, and 94% of participants in the correspondence group reported that receiving correspondence had helped them to understand their medical condition.

CONCLUSION

Patients wish to receive copies of their correspondence and feel it improves their understanding of their medical condition. Although we were unable to demonstrate a measurable reduction in anxiety, increase in understanding or satisfaction, we recommend that patients be offered the choice of receiving copies of their clinic correspondence and endoscopy reports.

Syntheses of Bipyricorroles and Their Meso-Meso Coupled Dimers

The metal-templated condensation strategy has been developed for the synthesis of meso-free bipyricorrole complexes. The reactive meso-CH in the monomer complex is further treated with various oxidative coupling reagents such as AgPF₆, AgOTf, and FeCl₃. Unlike Ag(I) salts, the FeCl₃ resulted in a meso-meso-linked corrole homologue dimer. The synthetic methodologies successfully introduce the Pd^II monomer as well as Pd^II-Pd^II dimeric complexes in the corrole chemistry.

Detection and Control of Spin-Orbit Interactions in a GaAs Hole Quantum Point Contact

We investigate the relationship between the Zeeman interaction and the inversion-asymmetry-induced spin-orbit interactions (Rashba and Dresselhaus SOIs) in GaAs hole quantum point contacts. The presence of a strong SOI results in the crossing and anticrossing of adjacent spin-split hole subbands in a magnetic field. We demonstrate theoretically and experimentally that the anticrossing energy gap depends on the interplay between the SOI terms and the highly anisotropic hole g tensor and that this interplay can be tuned by selecting the crystal axis along which the current and magnetic field are aligned. Our results constitute the independent detection and control of the Dresselhaus and Rashba SOIs in hole systems, which could be of importance for spintronics and quantum information applications.

The longest tumor diameter in one dimension as a predictor for skeletal metastasis in renal cell carcinoma

INTRODUCTION

Renal cell carcinoma (RCC) comprises a diverse group of malignant neoplasms that have multifarious histopathological features and biological behavior. One-third of RCC patients develops skeletal metastasis with a poor 5-year survival rate. Data explaining how some of these tumors show sooner bony metastasis than expected is sparse. The objective of this study was to identify whether tumor size can act as a predictor of bony metastases among patients of RCC.

MATERIALS AND METHODS

We retrospectively reviewed contrast enhanced computed tomography (CECT) scan and clinical records of 66 patients with RCC, who fulfilled specified inclusion criteria. Patients who had bony metastasis at the time of presentation were selected as case and those without skeletal metastasis were referred to as controls. Receiver operating characteristic (ROC) curve analysis was used to determine the appropriate cut-off value for tumor size, which was measured as the longest tumor diameter (LTD) in one-dimensional (1D).

RESULTS

Of the 66 patients selected, 30% developed bone metastasis. The tumor size of RCCs significantly correlated with the presence of skeletal metastasis in our study. None of the patients with 1D LTD <4.8 cm on CECT were found to have skeletal metastasis. ROC analysis revealed that the accuracy of the LTD in predicting bone metastasis was high with an area under ROC curve of 0.823. A cut-off value of 7.5 cm had a sensitivity of 78.9% and specificity of 80.9%.

CONCLUSION

The 1D LTD with a cut-off value of 7.5 cm, at the time of presentation is an important predictor of skeletal metastasis. The result of this study may have role in triage of patients into a subgroup which mandates more aggressive treatment and monitoring.

Modulation of Calmodulin and Protein Kinase C Activities by Pencillium Mycotoxins

Calmodulin (CaM), a calcium-binding protein, is found in high concentrations in mammalian brain where it plays a pivotal role in a large number of cellular functions. Protein kinase C (PKC), a multifunctional cytosolic enzyme, in the presence of both Ca2+ and phospholipids, transduce extracellular signals into intracellu-lar events. Both CaM and PKC are partially involved in maintaining Ca2+ homeostasis in the cell. Any fluctuations in the intracel-lular Ca2+ can modulate cellular functions and may contribute to neuronal dysfunction. Hence, the present investigation was initiated to study the effects of some selected penicillium (naturally occurring tremorgenic) mycotoxins like secalonic acid, citreoviridin, and verruculogen on CaM activity, active conformation of CaM and PKC activity. Stimulation of CaM-deflcient bovine brain 3′-5′ phosphodieste rase (PDE) indicated CaM activity. The modification of CaM active conformation was studied by the binding of fluorescent probe N-phenyl-1-napthylamine (NPN) to CaM. Alterations in the fluorescence of dansyl-CaM was used to study the effect of these compounds on complex formation between CaM and PDE. Rat brain cytosolic PKC was studied using 32P-ATP as a measure of altered protein phosphorylation. The concentrations of mycotoxins used were in the range of 10 to 50 μM. All three mycotoxins inhibited CaM-stimulated PDE activity in a concentration-dependent manner. Citreoviridin and secalonic acid inhibited NPN fluorescence and Ca2+-dependent complex formation of dansyl-CaM and PDE. The IC50 values for NPN fluorescence of citreoviridin and secalonic acid were 13 μM and 19 μM respectively. However, verruculogen showed little effect on NPN fluorescence and the Ca2+-dependent complex formation of dansyl-CaM and PDE. These mycotoxins also inhibited PKC activity in a concentration-dependent manner with IC50 values of 19.8, 25.7, and 38.4 μM for secalonic acid, citreoviridin, and verruculogen, respectively. The results of our study suggest that these mycotoxins at very low concentrations are interacting with CaM and PKC. Such an effect could lead to impairment of neurotransmission and result in neurotoxicity.

Eiger-induced cell death relies on Rac1-dependent endocytosis

Signaling via tumor necrosis factor receptor (TNFR) superfamily members regulates cellular life and death decisions. A subset of mammalian TNFR proteins, most notably the p75 neurotrophin receptor (p75NTR), induces cell death through a pathway that requires activation of c-Jun N-terminal kinases (JNKs). However the receptor-proximal signaling events that mediate this remain unclear. Drosophila express a single tumor necrosis factor (TNF) ligand termed Eiger (Egr) that activates JNK-dependent cell death. We have exploited this model to identify phylogenetically conserved signaling events that allow Egr to induce JNK activation and cell death in vivo. Here we report that Rac1, a small GTPase, is specifically required in Egr-mediated cell death. rac1 loss of function blocks Egr-induced cell death, whereas Rac1 overexpression enhances Egr-induced killing. We identify Vav as a GEF for Rac1 in this pathway and demonstrate that dLRRK functions as a negative regulator of Rac1 that normally acts to constrain Egr-induced death. Thus dLRRK loss of function increases Egr-induced cell death in the fly. We further show that Rac1-dependent entry of Egr into early endosomes is a crucial prerequisite for JNK activation and for cell death and show that this entry requires the activity of Rab21 and Rab7. These findings reveal novel regulatory mechanisms that allow Rac1 to contribute to Egr-induced JNK activation and cell death.