Bounds on the entries of the principal eigenvector of the distance signless Laplacian matrix

Das, K.Ch.,da Silva Junior, C.M.,de Freitas, M.A.A.,Del-Vecchio, R.R. North Holland [etc.] 2015 Linear Algebra and its Applications Vol.483 No.-

The distance signless Laplacian spectral radius of a connected graph G is the largest eigenvalue of the distance signless Laplacian matrix of G, defined as D<SUP>Q</SUP>(G)=Tr(G)+D(G), where D(G) is the distance matrix of G and Tr(G) is the diagonal matrix of vertex transmissions of G. In this paper we determine upper and lower bounds on the minimal and maximal entries of the principal eigenvector of D<SUP>Q</SUP>(G) and characterize the extremal graphs. In addition, we obtain a lower bound on the distance signless Laplacian spectral radius of G based on its order and independence number, and characterize the extremal graph.

Effective Parameters for Gait Analysis in Experimental Models for Evaluating Peripheral Nerve Injuries in Rats

Ivair Matias Júnior,Priscila Medeiros,Renato Leonardo de Freita,Hilton Vicente-César,José Raniery Ferreira Junior,Hélio Rubens Machado,Rafael Menezes-Reis 대한척추신경외과학회 2019 Neurospine Vol.16 No.2

Objective: Chronic constriction injury (CCI) of the sciatic nerve is a peripheral nerve injury widely used to induce mononeuropathy. This study used machine learning methods to identify the best gait analysis parameters for evaluating peripheral nerve injuries. Methods: Twenty-eight male Wistar rats (weighing 270±10 g), were used in the present study and divided into the following 4 groups: CCI with 4 ligatures around the sciatic nerve (CCI-4L; n=7), a modified CCI model with 1 ligature (CCI-1L; n=7), a sham group (n=7), and a healthy control group (n=7). All rats underwent gait analysis 7 and 28 days postinjury. The data were evaluated using Kinovea and WeKa software (machine learning and neural networks). Results: In the machine learning analysis of the experimental groups, the pre-swing (PS) angle showed the highest ranking in all 3 analyses (sensitivity, specificity, and area under the receiver operating characteristics curve using the Naive Bayes, k-nearest neighbors, radial basis function classifiers). Initial contact (IC), step length, and stride length also performed well. Between 7 and 28 days after injury, there was an increase in the total course time, step length, stride length, stride speed, and IC, and a reduction in PS and IC-PS. Statistically significant differences were found between the control group and experimental groups for all parameters except speed. Interactions between time after injury and nerve injury type were only observed for IC, PS, and IC-PS. Conclusion: PS angle of the ankle was the best gait parameter for differentiating nonlesions from nerve injuries and different levels of injury.

Moderate rest intervals are superior to short intervals for improving PAI-1 following exhaustive exercise in recreational weightlifters

Fabrício Eduardo Rossi,Jose Gerosa-Neto,Tiego Aparecido Diniz,Ismael F. Freitas Junior,Fabio Santos Lira,Jason Michael Cholewa 한국운동재활학회 2016 JER Vol.12 No.6

Synthesis and biological evaluation of 2-acetamidothiophene-3-carboxamide derivatives against Leishmania donovani

Oh, S.,Kwon, B.,Kong, S.,Yang, G.,Lee, N.,Han, D.,Goo, J.,Siqueira-Neto, J.,Freitas-Junior, L.,Liuzzi, M. TEH ROYAL SOCIETY OF CHEMISTRY 2014 MedChemComm Vol.5 No.2

A high-throughput (HTS) and high-content screening (HCS) campaign of a commercial library identified 2-acetamidothophen-3-carboxamide as a novel scaffold for developing new anti-leishmanial agents. A series of chemical modifications were performed to study the structure-activity relationship (SAR) and in vitro anti-leishmanial activities were evaluated using biological assays of not only extracellular promastigotes but also intracellular amastigotes. Compound 6a showed promising anti-amastigote activity (EC50 = 6.41 mu M) against L. donovani without any cytotoxicity (CC50 > 50 mu M) towards human macrophages.

Discovery of Carbohybrid-Based 2-Aminopyrimidine Analogues As a New Class of Rapid-Acting Antimalarial Agents Using Image-Based Cytological Profiling Assay

Lee, Sukjun,Lim, Donghyun,Lee, Eunyoung,Lee, Nakyung,Lee, Hong-gun,Cechetto, Jonathan,Liuzzi, Michel,Freitas-Junior, Lucio H.,Song, Jin Sook,Bae, Myung Ae,Oh, Sangmi,Ayong, Lawrence,Park, Seung Bum American Chemical Society 2014 Journal of medicinal chemistry Vol.57 No.17

<P>New antimalarial agents that exhibit multistage activities against drug-resistant strains of malaria parasites represent good starting points for developing next-generation antimalarial therapies. To facilitate the progression of such agents into the development phase, we developed an image-based parasitological screening method for defining drug effects on different asexual life cycle stages of <I>Plasmodium falciparum</I>. High-throughput screening of a newly assembled diversity-oriented synthetic library using this approach led to the identification of carbohybrid-based 2-aminopyrimidine compounds with fast-acting growth inhibitory activities against three laboratory strains of multidrug-resistant <I>P. falciparum</I>. Our structure–activity relationship study led to the identification of two derivatives (<B>8aA</B> and <B>11aA</B>) as the most promising antimalarial candidates (mean EC<SUB>50</SUB> of 0.130 and 0.096 μM against all three <I>P. falciparum</I> strains, selectivity indices >600, microsomal stabilities >80%, and mouse malaria ED<SUB>50</SUB> values of 0.32 and 0.12 mg/kg/day, respectively), targeting all major blood stages of multidrug-resistant <I>P. falciparum</I> parasites.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jmcmar/2014/jmcmar.2014.57.issue-17/jm5009693/production/images/medium/jm-2014-009693_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jm5009693'>ACS Electronic Supporting Info</A></P>

Chemosensitization potential of P-glycoprotein inhibitors in malaria parasites

Alcantara, L.M.,Kim, J.,Moraes, C.B.,Franco, C.H.,Franzoi, K.D.,Lee, S.,Freitas-Junior, L.H.,Ayong, L.S. Academic Press 2013 Experimental parasitology Vol.134 No.2

Members of the ATP-binding cassette (ABC)-type transporter superfamily have been implicated in multidrug resistance in malaria, and various mechanistic models have been postulated to explain their interaction with diverse antimalarial drugs. To gain insight into the pharmacological benefits of inhibiting ABC-type transporters in malaria chemotherapy, we investigated the in vitro chemosensitization potential of various P-glycoprotein inhibitors. A fluorescent chloroquine derivative was synthesized and used to assess the efflux dynamics of chloroquine in MDR and wild type Plasmodium falciparum parasites. This novel BODIPY-based probe accumulated in the digestive vacuole (DV) of CQ-sensitive parasites but less so in MDR cells. Pre-exposure of the MDR parasites to non-cytocidal concentrations of unlabeled chloroquine resulted in a diffused cytoplasmic retention of the probe whereas a similar treatment with the CQR-reversing agent, chlorpheniramine, resulted in DV accumulation. A diffused cytoplasmic distribution of the probe was also obtained following treatment with the P-gp specific inhibitors zosuquidar and tariquidar, whereas treatments with the tyrosine kinase inhibitors gefitinib or imatinib produced a partial accumulation within the DV. Isobologram analyses of the interactions between these inhibitors and the antimalarial drugs chloroquine, mefloquine, and artemisinin revealed distinct patterns of drug synergism, additivity and antagonism. Taken together, the data indicate that competitive tyrosine kinase and noncompetitive P-glycoprotein ATPase-specific inhibitors represent two new classes of chemosensitizing agents in malaria parasites, but caution against the indiscriminate use of these agents in antimalarial drug combinations.

An Image-Based High-Content Screening Assay for Compounds Targeting Intracellular <i>Leishmania donovani</i> Amastigotes in Human Macrophages

Siqueira-Neto, Jair L.,Moon, Seunghyun,Jang, Jiyeon,Yang, Gyongseon,Lee, Changbok,Moon, Hong Kee,Chatelain, Eric,Genovesio, Auguste,Cechetto, Jonathan,Freitas-Junior, Lucio H. Public Library of Science 2012 PLoS neglected tropical diseases Vol.6 No.6

<▼1><P>Leishmaniasis is a tropical disease threatening 350 million people from endemic regions. The available drugs for treatment are inadequate, with limitations such as serious side effects, parasite resistance or high cost. Driven by this need for new drugs, we developed a high-content, high-throughput image-based screening assay targeting the intracellular amastigote stage of different species of <I>Leishmania</I> in infected human macrophages. The <I>in vitro</I> infection protocol was adapted to a 384-well-plate format, enabling acquisition of a large amount of readouts by automated confocal microscopy. The reading method was based on DNA staining and required the development of a customized algorithm to analyze the images, which enabled the use of non-modified parasites. The automated analysis generated parameters used to quantify compound activity, including infection ratio as well as the number of intracellular amastigote parasites and yielded cytotoxicity information based on the number of host cells. Comparison of this assay with one that used the promastigote form to screen 26,500 compounds showed that 50% of the hits selected against the intracellular amastigote were not selected in the promastigote screening. These data corroborate the idea that the intracellular amastigote form of the parasite is the most appropriate to be used in primary screening assay for <I>Leishmania</I>.</P></▼1><▼2><P><B>Author Summary</B></P><P>Leishmaniasis, one of the most neglected tropical diseases, affects over 2 million people each year. Visceral leishmaniasis (VL), also known as Kala-azar, is caused by the protozoan parasites <I>Leishmania donovani</I> and <I>Leishmania infantum</I> and is fatal if left untreated. Because existing treatments are often ineffective due to parasite resistance and/or toxicity new drugs are urgently needed. Leishmaniasis is transmitted to humans by the bite of an infected sandfly. In the insect vector, parasites exist as flagellated forms—promastigotes, which infect macrophage cells of the human host, where they differentiate to round forms known as amastigotes. Amastigotes and promastigotes are substantially different from a molecular perspective. Drug discovery for leishmaniasis has traditionally been complicated by the unavailability of validated drug targets and of relevant drug assays. Whole cell-based assays have been widely used, as they bypass the need for a validated target. However, they use the insect form of the parasite; indeed, the human form, the intracellular amastigote, is difficult to obtain in the laboratory in quantities compatible with drug screening. We describe here the technical advances that made it possible to adapt the intracellular amastigote form of <I>L. donovani</I> to a drug assay compatible with high-throughput screening.</P></▼2>

Identification of Novel Compounds Inhibiting Chikungunya Virus-Induced Cell Death by High Throughput Screening of a Kinase Inhibitor Library

Cruz, Deu John M.,Bonotto, Rafaela M.,Gomes, Rafael G. B.,da Silva, Camila T.,Taniguchi, Juliana B.,No, Joo Hwan,Lombardot, Benoit,Schwartz, Olivier,Hansen, Michael A. E.,Freitas-Junior, Lucio H. Public Library of Science 2013 PLoS neglected tropical diseases Vol.7 No.10

<▼1><P>Chikungunya virus (CHIKV) is a mosquito-borne arthrogenic alphavirus that causes acute febrile illness in humans accompanied by joint pains and in many cases, persistent arthralgia lasting weeks to years. The re-emergence of CHIKV has resulted in numerous outbreaks in the eastern hemisphere, and threatens to expand in the foreseeable future. Unfortunately, no effective treatment is currently available. The present study reports the use of resazurin in a cell-based high-throughput assay, and an image-based high-content assay to identify and characterize inhibitors of CHIKV-infection in vitro. CHIKV is a highly cytopathic virus that rapidly kills infected cells. Thus, cell viability of HuH-7 cells infected with CHIKV in the presence of compounds was determined by measuring metabolic reduction of resazurin to identify inhibitors of CHIKV-associated cell death. A kinase inhibitor library of 4,000 compounds was screened against CHIKV infection of HuH-7 cells using the resazurin reduction assay, and the cell toxicity was also measured in non-infected cells. Seventy-two compounds showing ≥50% inhibition property against CHIKV at 10 µM were selected as primary hits. Four compounds having a benzofuran core scaffold (CND0335, CND0364, CND0366 and CND0415), one pyrrolopyridine (CND0545) and one thiazol-carboxamide (CND3514) inhibited CHIKV-associated cell death in a dose-dependent manner, with EC<SUB>50</SUB> values between 2.2 µM and 7.1 µM. Based on image analysis, these 6 hit compounds did not inhibit CHIKV replication in the host cell. However, CHIKV-infected cells manifested less prominent apoptotic blebs typical of CHIKV cytopathic effect compared with the control infection. Moreover, treatment with these compounds reduced viral titers in the medium of CHIKV-infected cells by up to 100-fold. In conclusion, this cell-based high-throughput screening assay using resazurin, combined with the image-based high content assay approach identified compounds against CHIKV having a novel antiviral activity - inhibition of virus-induced CPE - likely by targeting kinases involved in apoptosis.</P></▼1><▼2><P><B>Author Summary</B></P><P>Recent outbreaks and expanding global distribution of Chikungunya virus (CHIKV) in different regions of Asia, Africa and Europe necessitates the development of effective therapeutic interventions. At present, only two antiviral compounds (chloroquine and ribavirin) that inhibit viral infection <I>in vitro</I> have been used in clinical cases of chikungunya infections. However, neither of these compounds have shown strong efficacy in vivo. Recent attempts to identify new antiviral candidates for CHIKV using cell-based phenotypic approach have been reported. In this study, we developed a simple cell-based high-throughput assay using resazurin to identify potential anti-CHIKV compounds. This high-throughput assay is based on the metabolic reduction of resazurin to the highly fluorescent resorufin by viable cells as an indicator of activity against CHIKV-induced CPE. We screened 4,000 small molecules belonging to the BioFocus kinase inhibitor chemical library and found a cluster of related molecules with antiviral activity against CHIKV. Finally, we characterized the putative mode of action of these active compounds using an image-based high content assay and conventional virological methods (<I>i.e.</I>, virus yield reduction assay, microneutralization assay).</P></▼2>

Combined training (strength plus aerobic) potentiates a reduction in body fat but only functional training reduced low-density lipoprotein cholesterol in postmenopausal women with a similar training load

Fabrício Eduardo Rossi,Ana Claudia S. Fortaleza,Lucas M. Neves,Tiego A. Diniz,Marcela R. de Castro,Camila Buonani,Jorge Mota,Ismael F. Freitas Junior 한국운동재활학회 2017 JER Vol.13 No.3

The aim of this study was to compare the effects of combined (CT; strength plus aerobic) and functional training (FT) on the body composition and metabolic profile with a similar training load in postmenopausal women. The participants were divided into three groups: CT (n= 20), FT (n= 17), and control group (CG, n= 15). The trunk FM, fat mass (FM), percentage of FM (FM%), and fat-free mass were estimated by dual-energy X-ray absorptiometry. The metabolic profile, glucose, triacylglycerol, total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol (LDL-c) were assessed. There were main effects of time in trunk fat, FM, and FM% (P< 0.05). There were statistically significant interaction for FM (P= 0.015), FM% (P= 0.017) with lower values for CT group. For LDL-c, there was significant interaction (P= 0.002) with greater values for FT group in relation to CG and CT. Furthermore, when performed the post hoc test on the “mean absolute differences” (Δ), it can observed statistically significant difference between FT, CT, and CG (-13.0± 16.5 mg/dL vs. 4.8± 18.4 mg/dL vs. 9.2± 18.8 mg/dL, P< 0.05). In conclusion, when training loads are equivalent CT potentiated a reduction in FM and FM%, however, only FT reduced LDL-c in postmenopausal women.