Microsatellite typing and susceptibilities of serial Cryptococcus neoformans isolates from Cuban patients with recurrent cryptococcal meningitis

Contains fulltext : 124337.pdf (publisher's version ) (Open Access)BACKGROUND: Cryptococcus neoformans is commonly associated with meningoencephalitis in immunocompromised patients and occasionally in apparently healthy individuals. Recurrence of infection after initial treatment is not uncommon. We studied C. neoformans isolates from 7 Cuban patients with recurrent cryptococcal meningitis. Antifungal susceptibility and genotyping with microsatellite molecular typing were carried out. METHODS: Isolates (n = 19) were recovered from cerebrospinal fluid, blood, urine and semen. Antifungal susceptibilities for amphotericin B, fluconazole, flucytosine, itraconazole, voriconazole, posaconazole and isavuconazole were tested by CLSI M27A3 broth microdilution method. Genotyping was done using a panel of 9 microsatellite (STR) markers: (CT)n, (TG)n, (TA)n, (CTA)n, (TCT)n, (CCA)n, (TTAT)n, (ATCC)n and (TATT)n. RESULTS: The average number of isolates/patient was 2.71. The mean time interval between the collection of any two isolates was 52.5 days. All strains were identified as C. neoformans var. grubii (serotype Aalpha). Although none of the strains were resistant to the studied drugs, in serial isolates from two patients, MICs values of triazoles increased 4-5 log2 dilutions over time. STR patterns showed 14 distinctive profiles. In three patients the recurrent infection was associated with genotypically identical isolates. The four other patients had relapse isolates which were genotypically different from the initial infecting strain. CONCLUSION: Recurrences of cryptococcal meningitis in our series of patients was not associated with development of drug resistance of the original strain but by an initial infection with different strains or a reinfection with a new strain

Microbiological characteristics of clinical isolates of Cryptococcus spp. in Bahia, Brazil: molecular types and antifungal susceptibilities

To determine the profiles of susceptibility to antifungal and the genotypes of clinical isolates of Cryptococcus in Bahia, Brazil, 62 isolates were collected from cases of meningitis in the period from 2006 to 2010. Their susceptibilities to fluconazole, itraconazole, amphotericin B and 5-flucytosine were determined by the broth microdilution technique described by the Clinical and Laboratory Standards Institute and genotyping of the URA5 gene was accomplished by restriction fragment length polymorphism. C. neoformans accounted for 79% of the identified yeast and C. gattii represented the remaining 21%. Evaluation of the genotypes determined that 100% of the C. gattii isolates belong to the VGII genotype, and 98% of the C. neoformans isolates belong to the VNI genotype. Determination of susceptibility revealed isolates resistant to fluconazole (4.8%), 5-flucytosine (1.6%) and amphotericin B (3.2%); the stratification of sensitivity results for each species showed significant differences in susceptibility to azoles. This study is the first to describe the susceptibility profiles of molecular and clinical isolates of Cryptococcus in Bahia, Brazil. The high percentage of C. gattii isolates belonging to the VGII genotype and its lower susceptibility to antifungal agents highlight the importance of knowing which species are involved in cryptococcal infections in northeastern Brazil

Cryptophycins: cytotoxic cyclodepsipeptides with potential for tumor targeting

Weiss C, Figueras Agustí E, Borbély AN, Sewald N. Cryptophycins: cytotoxic cyclodepsipeptides with potential for tumor targeting. Journal of Peptide Science. 2017;23(7-8):514-531.Cryptophycins are a class of 16-membered highly cytotoxic macrocyclic depsipeptides isolated from cyanobacteria. The biological activity is based on their ability to interact with tubulin. They interfere with microtubule dynamics and prevent microtubules from forming correct mitotic spindles, which causes cell-cycle arrest and apoptosis. Their strong antiproliferative activities with 100-fold to 1000-fold potency compared with those of paclitaxel and vinblastine have been observed. Cryptophycins are highly promising drug candidates, as their biological activity is not negatively affected by P-glycoprotein, a drug efflux system commonly found in multidrug-resistant cancer cell lines and solid tumors. Cryptophycin-52 had been investigated in phase II clinical trials but failed because of its high neurotoxicity. Recently, cryptophycin conjugates with peptides and antibodies have been developed for targeted delivery in tumor therapy. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd

Physical conditions and chemical abundances in photoionized nebulae from optical spectra

This chapter presents a review on the latest advances in the computation of physical conditions and chemical abundances of elements present in photoionized gas H II regions and planetary nebulae). The arrival of highly sensitive spectrographs attached to large telescopes and the development of more sophisticated and detailed atomic data calculations and ionization correction factors have helped to raise the number of ionic species studied in photoionized nebulae in the last years, as well as to reduce the uncertainties in the computed abundances. Special attention will be given to the detection of very faint lines such as heavy-element recombination lines of C, N and O in H II regions and planetary nebulae, and collisionally excited lines of neutron-capture elements (Z >30) in planetary nebulae.Comment: Book Chapter. 31 pages. 6 Figures. Accepted for publication in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556

In vitro susceptibility to antifungal agents of environmental Cryptococcus spp. isolated in the city of Ribeirão Preto, São Paulo, Brazil

Infections by Cryptococcus strains other than C. neoformans have been detected in immunocompromised patients. Of these strains, three are considered human pathogens: C. albidus, C. laurenttii, and C. uniguttulatus. This study deals with the in vitro susceptibility of Cryptococcus to drugs such as amphotericin B, itraconazole, fluconazole, and 5-fluorocytosine. Environmental Cryptococcus isolates (50) distributed as follows: C. neoformans var. neoformans (16), C. albidus (17), C. laurentii (14), and C. uniguttulatus (3) were evaluated by the micro and macrodilution techniques, according to EUCAST and NCCLS recommendations, respectively. Considering both methodologies the respective minimal inhibitory concentrations (MIC) were 0.125 and 2 µg/ml for amphotericin B, 0.06 and 8 µg/ml for itraconazole, and 0.5 and more than 64 µg/ml for fluconazole and 5-fluorocytosine. Agreement percentages for the two methodologies were 100% for amphotericin B and fluconazole for all the strains tested. For itraconazole, the agreement percentage was 81.3% in the C. neoformans strain and 100% for all the others. All species had a agreement percentage of 94.1 to 100% when susceptibility to 5-fluorocytosine was tested. It is concluded that environmental isolates of C. neoformans var. neoformans, C. albidus, C. laurentii, and C. uniguttulatus may show high MICs against certain drugs, suggesting in vitro primary resistance to the antifungals tested

Catalyst-like Modulation of Transitions States for CFTR Channel Opening and Closing: New Stimulation Strategy Exploits Nonequilibrium Gating

Cystic fibrosis transmembrane conductance regulator (CFTR) is the chloride ion channel mutated in cystic fibrosi (CF) patients. It is an ATP-binding cassette protein, and its resulting cyclic nonequilibrium gating mechanism sets it apart from most other ion channels. The most common CF mutation (ΔF508) impairs folding of CFTR but also channel gating, reducing open probability (Po). This gating defect must be addressed to effectively treat CF. Combining single-channel and macroscopic current measurements in inside-out patches, we show here that the two effects of 5-nitro2-(3-phenylpropylamino)benzoate (NPPB) on CFTR, pore block and gating stimulation, are independent, suggesting action at distinct sites. Furthermore, detailed kinetic analysis revealed that NPPB potently increases Po, also of ΔF508 CFTR, by affecting the stability of gating transition states. This finding is unexpected, because for most ion channels, which gate at equilibrium, altering transition-state stabilities has no effect on Po; rather, agonists usually stimulate by stabilizing open states. Our results highlight how for CFTR, because of its unique cyclic mechanism, gating transition states determine Po and offer strategic targets for potentiator compounds to achieve maximal efficacy