Laminin‐γ1 chain and stress inducible protein 1 synergistically mediate PrPC‐dependent axonal growth via Ca2+ mobilization in dorsal root ganglia neurons

Prion protein (PrP^C) is a cell surface glycoprotein that is abundantly expressed in nervous system. The elucidation of the PrP^C interactome network and its significance on neural physiology is crucial to understanding neurodegenerative events associated with prion and Alzheimer's diseases. PrP^C co‐opts stress inducible protein 1/alpha7 nicotinic acetylcholine receptor (STI1/α7nAChR) or laminin/Type I metabotropic glutamate receptors (mGluR1/5) to modulate hippocampal neuronal survival and differentiation. However, potential cross‐talk between these protein complexes and their role in peripheral neurons has never been addressed. To explore this issue, we investigated PrP^C‐mediated axonogenesis in peripheral neurons in response to STI1 and laminin‐γ1 chain‐derived peptide (Ln‐γ1). STI1 and Ln‐γ1 promoted robust axonogenesis in wild‐type neurons, whereas no effect was observed in neurons from PrP^C‐null mice. PrP^C binding to Ln‐γ1 or STI1 led to an increase in intracellular Ca²⁺ levels via distinct mechanisms: STI1 promoted extracellular Ca²⁺ influx, and Ln‐γ1 released calcium from intracellular stores. Both effects depend on phospholipase C activation, which is modulated by mGluR1/5 for Ln‐γ1, but depends on, C‐type transient receptor potential (TRPC) channels rather than α7nAChR for STI1. Treatment of neurons with suboptimal concentrations of both ligands led to synergistic actions on PrP^C‐mediated calcium response and axonogenesis. This effect was likely mediated by simultaneous binding of the two ligands to PrP^C. These results suggest a role for PrP^C as an organizer of diverse multiprotein complexes, triggering specific signaling pathways and promoting axonogenesis in the peripheral nervous system.     

Brain changes in BDNF and S100B induced by ketogenic diets in Wistar rats

AimsWe investigated the effects of ketogenic diet (KD) on levels of tumor necrosis factor alpha (TNF-α, a classical pro-inflammatory cytokine), BDNF (brain-derived neurotrophic factor, commonly associated with synaptic plasticity), and S100B, an astrocyte neurotrophic cytokine involved in metabolism regulation.Main methodsYoung Wistar rats were fed during 8 weeks with control diet or two KD, containing different proportions of omega 6 and omega 3 polyunsaturated fatty acids. Contents of TNF-α, BDNF and S100B were measured by ELISA in two brain regions (hippocampus and striatum) as well as blood serum and cerebrospinal fluid.Key findingsOur data suggest that KD was able to reduce the levels of BDNF in the striatum (but not in hippocampus) and S100B in the cerebrospinal fluid of rats. These alterations were not affected by the proportion of polyunsaturated fatty acids offered. No changes in S100B content were observed in serum or analyzed brain regions. Basal TNF-α content was not affected by KD.SignificanceThese findings reinforce the importance of this diet as an inductor of alterations in the brain, and such changes might contribute to the understanding of the effects (and side effects) of KD in brain disorders.     

Cardiomyocyte dysfunction during the chronic phase of Chagas disease

Chagas disease, which is caused by the parasite Trypanosoma cruzi, is an important cause of heart failure. We investigated modifications in the cellular electrophysiological and calcium-handling characteristics of an infected mouse heart during the chronic phase of the disease. The patch-clamp technique was used to record action potentials (APs) and L-type Ca²⁺ and transient outward K⁺ currents. [Ca²⁺]_i changes were determined using confocal microscopy. Infected ventricular cells showed prolonged APs, reduced transient outward K⁺ and L-type Ca²⁺ currents and reduced Ca²⁺ release from the sarcoplasmic reticulum. Thus, the chronic phase of Chagas disease is characterised by cardiomyocyte dysfunction, which could lead to heart failure.     

The antimicrobial activity of lapachol and its thiosemicarbazone and semicarbazone derivatives

Lapachol was chemically modified to obtain its thiosemicarbazone and semicarbazone derivatives. These compounds were tested for antimicrobial activity against several bacteria and fungi by the broth microdilution method. The thiosemicarbazone and semicarbazone derivatives of lapachol exhibited antimicrobial activity against the bacteria Enterococcus faecalis and Staphylococcus aureus with minimal inhibitory concentrations (MICs) of 0.05 and 0.10 µmol/mL, respectively. The thiosemicarbazone and semicarbazone derivatives were also active against the pathogenic yeast Cryptococcus gattii (MICs of 0.10 and 0.20 µmol/mL, respectively). In addition, the lapachol thiosemicarbazone derivative was active against 11 clinical isolates of Paracoccidioides brasiliensis, with MICs ranging from 0.01-0.10 µmol/mL. The lapachol-derived thiosemicarbazone was not cytotoxic to normal cells at the concentrations that were active against fungi and bacteria. We synthesised, for the first time, thiosemicarbazone and semicarbazone derivatives of lapachol. The MICs for the lapachol-derived thiosemicarbazone against S. aureus, E. faecalis, C. gattii and several isolates of P. brasiliensis indicated that this compound has the potential to be developed into novel drugs to treat infections caused these microbes.     

Nontuberculous mycobacteria in respiratory samples from patients with pulmonary tuberculosis in the state of Rond?nia, Brazil

The main cause of pulmonary tuberculosis (TB) is infection with Mycobacterium tuberculosis (MTB). We aimed to evaluate the contribution of nontuberculous mycobacteria (NTM) to pulmonary disease in patients from the state of Rondônia using respiratory samples and epidemiological data from TB cases. Mycobacterium isolates were identified using a combination of conventional tests, polymerase chain reaction-based restriction enzyme analysis of hsp65 gene and hsp65 gene sequencing. Among the 1,812 cases suspected of having pulmonary TB, 444 yielded bacterial cultures, including 369 cases positive for MTB and 75 cases positive for NTM. Within the latter group, 14 species were identified as Mycobacterium abscessus, Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium intracellulare, Mycobacterium gilvum, Mycobacterium gordonae, Mycobacterium asiaticum, Mycobacterium tusciae, Mycobacterium porcinum, Mycobacterium novocastrense, Mycobacterium simiae, Mycobacterium szulgai, Mycobacterium phlei and Mycobacterium holsaticum and 13 isolates could not be identified at the species level. The majority of NTM cases were observed in Porto Velho and the relative frequency of NTM compared with MTB was highest in Ji-Paraná. In approximately half of the TB subjects with NTM, a second sample containing NTM was obtained, confirming this as the disease-causing agent. The most frequently observed NTM species were M. abscessus and M. avium and because the former species is resistant to many antibiotics and displays unsatisfactory cure rates, the implementation of rapid identification of mycobacterium species is of considerable importance.     

Potential geographical distribution of the red palm mite in South America

Among pests that have recently been introduced into the Americas, the red palm mite, Raoiella indica Hirst (Prostigmata: Tenuipalpidae), is the most invasive. This mite has spread rapidly to several Caribbean countries, United States of America, Mexico, Venezuela, Colombia and Brazil. The potential dispersion of R. indica to other regions of South America could seriously impact the cultivation of coconuts, bananas, exotic and native palms and tropical flowers such as the Heliconiaceae. To facilitate the development of efficacious R. indica management techniques such as the adoption of phytosanitary measures to prevent or delay the dispersion of this pest, the objective of this paper was to estimate the potential geographical distribution of R. indica in South America using a maximum entropy model. The R. indica occurrence data used in this model were obtained from extant literature, online databases and field sampling data. The model predicted potential suitable areas for R. indica in northern Colombia, central and northern Venezuela, Guyana, Suriname, east French Guiana and many parts of Brazil, including Roraima, the eastern Amazonas, northern Pará, Amapá and the coastal zones, from Pará to north of Rio de Janeiro. These results indicate the potential for significant R. indica related economic and social impacts in all of these countries, particularly in Brazil, because the suitable habitat regions overlap with agricultural areas for R. indica host plants such as coconuts and bananas.     

Diversity in proteinase specificity of thermophilic lactobacilli as revealed by hydrolysis of dairy and vegetable proteins

Ability of industrially relevant species of thermophilic lactobacilli strains to hydrolyze proteins from animal (caseins and β-lactoglobulin) and vegetable (soybean and wheat) sources, as well as influence of peptide content of growth medium on cell envelope-associated proteinase (CEP) activity, was evaluated. Lactobacillus delbrueckii subsp. lactis (CRL 581 and 654), L. delbrueckii subsp. bulgaricus (CRL 454 and 656), Lactobacillus acidophilus (CRL 636 and 1063), and Lactobacillus helveticus (CRL 1062 and 1177) were grown in a chemically defined medium supplemented or not with 1 % Casitone. All strains hydrolyzed mainly β-casein, while degradation of α_s-caseins was strain dependent. Contrariwise, κ-Casein was poorly degraded by the studied lactobacilli. β-Lactoglobulin was mainly hydrolyzed by CRL 656, CRL 636, and CRL 1062 strains. The L. delbrueckii subsp. lactis strains, L. delbrueckii subsp. bulgaricus CRL 656, and L. helveticus CRL 1177 degraded gliadins in high extent, while the L. acidophilus and L. helveticus strains highly hydrolyzed soy proteins. Proteinase production was inhibited by Casitone, the most affected being the L. delbrueckii subsp. lactis species. This study highlights the importance of proteolytic diversity of lactobacilli for rational strain selection when formulating hydrolyzed dairy or vegetable food products.     

Occurrence of alternariol and alternariol monomethyl ether in beverages from the Entre Rios Province market, Argentina

One hundred and eighty five samples of red, white and rosé wines and different juices purchased in Entre Rios, Argentina, were analyzed for the Alternaria mycotoxins alternariol (AOH) and alternariol methyl ether (AME). White wines were analyzed after removal of alcohol by a nitrogen stream and concentrated. AOH in red wines was cleaned up by solid-phase extraction columns in series (octadecyl and amino propyl modified silica) and AME quantified directly on the sample. The juices were filtered and concentrated, and then all sample extracts were quantified by high performance liquid chromatography with photodiode array detector that allows confirmation through UV spectra. Method validation revealed a good sensitivity with adequate LOD and LOQ for AME and less sensitivity for AOH (i.e. white wine: AME 0.8 and 1.4 ng/mL, AOH 2 and 3.3 ng/mL; red wine: AME 0.1 and 0.2 ng/mL, AOH 4.5 and 7.5 ng/mL; apple juice: AME 1.7 and 2.8 ng/mL, AOH 5 and 9 ng/mL; other juices: AME 2.0 and 3.1 ng/mL, AOH 6 and 10 ng/mL). Recoveries in all cases were greater than 80 %. Four of 53 white wine samples were contaminated with AOH with a maximum level of 18 ng/mL, 6 of 56 samples of red wine had a maximum of 13 ng/mL, and 3 of 68 samples of juices had traces of AOH. AME was less frequently detected than AOH, and the LOD and LOQ for AME are smaller than for AOH. Only three samples of white wine and one of red wine were contaminated, but in only one white wine sample (AME 225 ng/mL) did the toxin level exceed the LOQ.     

Vitamins K interact with N-terminus α-synuclein and modulate the protein fibrillization in vitro. Exploring the interaction between quinones and α-synuclein

In the last decades, a series of compounds, including quinones and polyphenols, has been described as having anti-fibrillogenic action on α-synuclein (α-syn) whose aggregation is associated to the pathogenesis of Parkinson’s disease (PD). Most of these molecules act as promiscuous anti-amyloidogenic agents, interacting with the diverse amyloidogenic proteins (mostly unfolded) through non-specific hydrophobic interactions. Herein we investigated the effect of the vitamins K (phylloquinone, menaquinone and menadione), which are 1,4-naphthoquinone (1,4-NQ) derivatives, on α-syn aggregation, comparing them with other anti-fibrillogenic molecules such as quinones, polyphenols and lipophilic vitamins. Vitamins K delayed α-syn fibrillization in substoichiometric concentrations, leading to the formation of short, sheared fibrils and amorphous aggregates, which are less prone to produce leakage of synthetic vesicles. In seeding conditions, menadione and 1,4-NQ significantly inhibited fibrils elongation, which could be explained by their ability to destabilize preformed fibrils of α-syn. Bidimensional NMR experiments indicate that a specific site at the N-terminal α-syn (Gly31/Lys32) is involved in the interaction with vitamins K, which is corroborated by previous studies suggesting that Lys is a key residue in the interaction with quinones. Together, our data suggest that 1,4-NQ, recently showed up by our group as a potential scaffold for designing new monoamine oxidase inhibitors, is also capable to modulate α-syn fibrillization in vitro.