Tachykinin NK-1 receptor probed with constrained analogues of substance P

The action of rotameric probes introduced either in position 7 or 8 in the sequence of substance P (SP) was investigated, i.e. -tetrahydroisoquinoleic acid (Tic), -fluorenylglycine (Flg), -diphenylalanine (Dip), the diastereoisomers of -1-indanylglycine (Ing) and -benz[ƒ]indanylglycine (Bfi), the Z- and E-isomers of dehydrophenylalanine and dehydronaphthylalanine (Δ^ZPhe, Δ^EPhe, Δ^ZNal, Δ^ENal) and (Dmp). The aim of this study was the topographical characterization of the binding subsites of human NK-1 receptor expressed in CHO cells, especially the S₇ and S₈ subsites, corresponding to residues Phe⁷ and Phe⁸ of substance P. According to the binding potencies of these substituted-SP analogues, the S₇ binding subsite is smaller than the S₈ subsite: the S₇ subsite accepts only one aromatic nucleus, while the S₈ can accommodate three coplanar nuclei altogether. These findings are compatible with the idea that the S₈ binding subsite may reside in the extracellular loops of the hNK-1 receptor. NK-1 agonists bind to human NK-1 receptor and activate the production of both inositol phosphates and cyclic AMP. As already quoted for septide, [pGlu⁶, Pro⁹]SP(6–11), discrepancies are observed between affinity (K_i) and activity (EC₅₀) values for IPs production. While a weak correlation between K_i and EC₅₀ values for IPs production could be found (r = 0.70), an excellent correlation could be demonstrated between their affinities (K_i) and their potencies (EC₅₀) for cAMP production (r = 0.97). The high potency (EC₅₀) observed for ‘septide-like’ molecules on PI hydrolysis, compared to their affinity is not an artefact related to the high level of NK-1 receptors expressed on CHO cells since a good correlation was found between EC₅₀ values obtained for PI hydrolysis and those measured for spasmogenic activity in guinea pig ileum bioassay (r = 0.94).

According to the binding potencies of constrained analogues of phenylalanine, the S₇ binding subsite of human NK-1 receptor is small, whereas the S₈, which can accommodate three coplanar nuclei, might probably reside in the extracellular loop. The discrepancies observed between affinity (K_i) and activity (EC₅₀) values for IPs production are not an artefact of CHO cells since a good correlation was found between EC₅₀ for PI hydrolysis and those measured in guinea pig ileum bioassay.     

Bladder tissue characterization using probe‐based Raman spectroscopy: Evaluation of tissue heterogeneity and influence on the model prediction

Existing approaches for early‐stage bladder tumor diagnosis largely depend on invasive and time‐consuming procedures, resulting in hospitalization, bleeding, bladder perforation, infection and other health risks for the patient. The reduction of current risk factors, while maintaining or even improving the diagnostic precision, is an underlying factor in clinical instrumentation research. For example, for clinic surveillance of patients with a history of noninvasive bladder tumors real‐time tumor diagnosis can enable immediate laser‐based removal of tumors using flexible cystoscopes in the outpatient clinic. Therefore, novel diagnostic modalities are required that can provide real‐time in vivo tumor diagnosis. Raman spectroscopy provides biochemical information of tissue samples ex vivo and in vivo and without the need for complicated sample preparation and staining procedures. For the past decade there has been a rise in applications to diagnose and characterize early cancer in different organs, such as in head and neck, colon and stomach, but also different pathologies, for example, inflammation and atherosclerotic plaques. Bladder pathology has also been studied but only with little attention to aspects that can influence the diagnosis, such as tissue heterogeneity, data preprocessing and model development. The present study presents a clinical investigative study on bladder biopsies to characterize the tumor grading ex vivo, using a compact fiber probe‐based imaging Raman system, as a crucial step towards in vivo Raman endoscopy. Furthermore, this study presents an evaluation of the tissue heterogeneity of highly fluorescent bladder tissues, and the multivariate statistical analysis for discrimination between nontumor tissue, and low‐ and high‐grade tumor.     

Robust algorithm for brain magnetic resonance image (MRI) classification based on GARCH variances series

In this paper, a robust algorithm for disease type determination in brain magnetic resonance image (MRI) is presented. The proposed method classifies MRI into normal or one of the seven different diseases. At first two-level two-dimensional discrete wavelet transform (2D DWT) of input image is calculated. Our analysis show that the wavelet coefficients of detail sub-bands can be modeled by generalized autoregressive conditional heteroscedasticity (GARCH) statistical model. The parameters of GARCH model are considered as the primary feature vector. After feature vector normalization, principal component analysis (PCA) and linear discriminant analysis (LDA) are used to extract the proper features and remove the redundancy from the primary feature vector. Finally, the extracted features are applied to the K-nearest neighbor (KNN) and support vector machine (SVM) classifiers separately to determine the normal image or disease type. Experimental results indicate that the proposed algorithm achieves high classification rate and outperforms recently introduced methods while it needs less number of features for classification.     

A new discriminant NMF algorithm and its application to the extraction of subtle emotional differences in speech

In this study we propose a new feature extraction algorithm, dNMF (discriminant non-negative matrix factorization), to learn subtle class-related differences while maintaining an accurate generative capability. In addition to the minimum representation error for the standard NMF (non-negative matrix factorization) algorithm, the dNMF algorithm also results in higher between-class variance for discriminant power. The multiplicative NMF learning algorithm has been modified to cope with this additional constraint. The cost function was carefully designed so that the extraction of feature coefficients from a single testing pattern with pre-trained feature vectors resulted in a quadratic convex optimization problem in non-negative space for uniqueness. It also resolves issues related to the previous discriminant NMF algorithms. The developed dNMF algorithm has been applied to the emotion recognition task for speech, where it needs to emphasize the emotional differences while de-emphasizing the dominant phonetic components. The dNMF algorithm successfully extracted subtle emotional differences, demonstrated much better recognition performance and showed a smaller representation error from an emotional speech database.     

Tendinopathy diagnosis and treatment monitoring using attenuated total reflectance‐Fourier transform infrared spectroscopy

Tendinopathy, an important sports injury afflicting athletes and general public, is associated with huge economic losses. The currently used diagnostic tests are subjective, show moderate sensitivity and specificity; while treatment failures persist despite advances in therapy. This highlights the need for tendinopathy diagnostic and treatment monitoring tools. This study investigates tendon injury, natural healing and effect of treatment using ATR‐FTIR complemented with histopathology. Control (C), injured (I) and treated (T) rat tendons were extracted 3, 7, 14 and 28 days post‐injury/treatment, representing phases of healing; and subjected to hematoxylin & eosin staining as well as spectroscopy. While C showed no change, I‐ and T‐related histological changes could be clearly observed in stained sections. ATR‐FTIR spectra highlighted the biochemical changes within groups. Multivariate analysis could classify C, I and T with 75%; different days between groups with 84%; and different days within group with 65% efficiency. Results suggest that such analysis can not only identify C, I or T but also different phases of healing. Difference between I and T at different time points also suggest change in rate of healing. Further studies may help develop this technique for clinical diagnosis and treatment monitoring in future.      

Substituted α-mercaptoketones,new types of specific neprilysin inhibitors

New neprilysin inhibitors containing an α-mercaptoketone HSC(R¹R²)CO group, as zinc ligand were designed. Two parameters were explored for potency optimization: the size of the inhibitor which could interact with the S₁, S₁′ or S₂′ domain of the enzyme and the nature of the substituents R¹, R² of the mercaptoketone group. Introduction of a cyclohexyl chain in R¹, R² position and a (3-thiophen)benzyl group in position R³ (compound 12n) yielded to the most potent inhibitor of this series with a Ki value of 2 ± 0.3 nM. This result suggests that this new inhibitor interacts within the S₁, S₁′ domain of NEP allowing a pentacoordination of the catalytic Zn²⁺ ion by the mercaptoketone moiety.     

Synthesis and biological evaluation of aminothiazoles against Histoplasma capsulatum and Cryptococcus neoformans

The design and synthesis of a library of forty novel 2-aminoazole analogues as well as their evaluation as antifungal compounds against Histoplasma capsulatum and Cryptococcus neoformans is described. These structures were derived from N-[5-(1-naphthalenylmethyl)-2-thiazolyl]cyclohexanecarboxamide (41F5), a fungistatic agent previously identified through phenotypic screening (Antimicrob Agents Chemother. 2013;57:4349). Modifications to improve potency and water-solubility of 41F5 focused primarily on the 5-naphthalenyl group, the thiazole core, and the methylene linker between these two structural elements. In general, compounds with lipophilic [5+6] bicyclic ring systems, such as the 7-benzothiophenyl- and 4-indanyl groups, at the 5-position were 2–3 times more active against both fungal species as compared to 41F5. Also, introduction of a carbonyl group at the methylene linker of 41F5 resulted in a 2–3-fold increase in potency. These highly active compounds also showed generally low toxicities against murine P388D1 macrophages resulting in selectivity indices ranging from 63 to >200. Compounds that were highly active against fluconazole-sensitive C. neoformans strains had almost identical activity against fluconazole-resistant variants of this fungus indicating that 14α-demethylase is not their molecular target. Highly active compounds also retained activity against H. capsulatum phagocytosed into P388D1 macrophages.     

Discovery of a new class of valosine containing protein (VCP/P97) inhibitors for the treatment of non-small cell lung cancer

Valosine containing protein (VCP/p97) is a member of the AAA ATPase family involved in several essential cellular functions and plays an important role in the ubiquitin-mediated degradation of misfolded proteins. P97 has a significant role in maintaining the cellular protein homeostasis for tumor cell growth and survival and has been found overexpressed in many tumor types. No new molecule entities based on p97 target were approved in clinic. Herein, a series of novel pyrimidine structures as p97 inhibitors were designed and synthesized. After enzymatic evaluations, structure-activity relationships (SAR) were discussed in detailed. Among the screened compounds, derivative 35 showed excellent enzymatic inhibitory activity (IC₅₀, 36?nM). The cellular inhibition results showed that compound 35 had good antiproliferative activity against the non-small cell lung cancer A549 cells (IC₅₀, 1.61?μM). Liver microsome stability showed that the half-life of compound 35 in human liver microsome was 42.3?min, which was more stable than the control CB-5083 (25.8?min). The in vivo pharmacokinetic results showed that the elimination phase half-lives of compound 35 were 4.57?h for ig and 3.64?h for iv, respectively and the oral bioavailability was only 4.5%. These results indicated that compound 35 could be effective for intravenous treatment of non-small cell lung cancer.     

Discovery of a novel class of potent and selective tetrahydroindazole-based sigma-1 receptor ligands

The sigma-1 and sigma-2 receptors have been shown to play important roles in CNS diseases, cancer, and other disorders. These findings suggest that targeting these proteins with small-molecule modulators may be of important therapeutic value. Here we report the development of a new class of tetrahydroindazoles that are highly potent and selective ligands for sigma-1. Molecular modeling was used to rationalize the observed structure-activity relationships and identify key interactions responsible for increased potency of the optimized compounds. Assays for solubility and microsomal stability showed this series possesses favorable characteristics and is amenable to further therapeutic development. The compounds described herein will be useful in the development of new chemical probes for sigma-1 and to aid in future work therapeutically targeting this protein.     

Ketamine esters and amides as short-acting anaesthetics: Structure-activity relationships for the side-chain

N-Aliphatic ester analogues of the non-opioid ketamine (1) retain effective anaesthetic/analgesic properties while minimising ketamine’s psychomimetic side-effects. We show that the anaesthetic/analgesic properties of these ester analogues depend critically on the length (from 2 to 4 carbons), polarity and steric cross-section of the aliphatic linker chain. More stable amide and ethylsulfone analogues generally showed weaker anaesthetic/analgesic activity. There was no correlation between the anaesthetic/analgesic properties of the compounds and their binding affinities for the N-methyl-d-aspartate (NMDA) receptor.