Role of Estradiol in the Regulation of Prolactin Secretion During Late Pregnancy

Estrogen action is necessary for evidencing the stimulatory action of mifepristone and naloxone on prolactin (PRL) secretion during late pregnancy. Our aim is to determine the mechanism mediating this facilitator action of estrogens. To investigate the hypothalamic mechanisms involved in estrogen actions in PRL secretion at the end of pregnancy, we measured the effect of pretreatment with the estrogen antagonist tamoxifen on the expression of tyrosine hydroxylase (TH), hormone receptors (ERα and β, PRs, PRLR_(long)), and μ- and κ- opioid receptors (ORs) at mRNA (by semiquantitative RT-PCR) and protein (by western blot for TH, PRLR_(long), ERα, PRs, μ- and ORs) levels in extracts of medial basal hypothalamus (MBH) and serum PRL, E₂ and P₄ levels (by RIA) in mifepristone- and naloxone-treated rats. Tamoxifen administration partially prevented PRL release induced by the combined treatment. TH expression diminished and ERα expression increased in mifepristone-treated rats at mRNA and protein levels and tamoxifen partially prevented these changes with no effect on PRs expression. Mifepristone increased PRLR_(long) mRNA levels; this increase was blocked by tamoxifen. Combined tamoxifen and mifepristone treatment decreased μ- and k-ORs mRNA but not protein levels. In conclusion, E₂ induces neuroadaptive mechanisms necessary to facilitate PRL release preceding delivery. Acting through ERα, E₂ modulates hypothalamic dopaminergic neurons activity, regulating TH, μ- and κ-ORs and PRLR_(long) expression, and is necessary for evidencing the effects of P₄ withdrawal. Its presence on days 14 and 15 of pregnancy is crucial to facilitate the opioid system modulation of PRL secretion at the end of pregnancy in the rat.     

Hydrolysis of Pork Muscle Sarcoplasmic Proteins by Lactobacillus curvatus and Lactobacillus sake

Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were selected on the basis of their proteolytic activities against synthetic substrates. Further, the effects of whole cells, cell extracts, and a combination of both enzymatic sources on muscle sarcoplasmic proteins were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography analyses. Strains of both species displayed proteinase activities on five sarcoplasmic proteins. The inoculation of whole cells caused a degradation of peptides, whereas the addition of cell extracts resulted in the generation of both hydrophilic and hydrophobic peptides. This phenomenon was remarkably more pronounced when L. curvatus was involved. Whole cells also consumed a great amount of free amino acids, while the addition of intracellular enzymes contributed to their generation. L. sake accounted for a greater release of free amino acids. In general, cell viability and also proteolytic events were promoted when cell suspensions were provided with cell extracts as an extra source of enzymes.     

Cytogenetic evidences on the evolutionary relationships between the tetraploids of the section <Emphasis Type="Italic">Rhizomatosae</Emphasis> and related diploid species (<Emphasis Type="Italic">Arachis</Emphasis>, Leguminosae)

Rhizomatosae is a taxonomic section of the South American genus Arachis, whose diagnostic character is the presence of rhizomes in all its species. This section is of particular evolutionary interest because it has three polyploid (A. pseudovillosa, A. nitida and A. glabrata, 2n?=?4x?=?40) and only one diploid (A. burkartii, 2n?=?2x?=?20) species. The phylogenetic relationships of these species as well as the polyploidy nature and the origin of the tetraploids are still controversial. The present study provides an exhaustive analysis of the karyotypes of all rhizomatous species and six closely related diploid species of the sections Erectoides and Procumbentes by cytogenetic mapping of DAPI/CMA heterochromatin bands and 5S and 18–26S rDNA loci. Chromosome banding showed variation in the DAPI heterochromatin distribution pattern, which, together with the number and distribution of rDNA loci, allowed the characterization of all species studied here. The bulk of chromosomal markers suggest that the three rhizomatous tetraploid species constitute a natural group and may have at least one common diploid ancestor. The cytogenetic data of the diploid species analyzed evidenced that the only rhizomatous diploid species—A. burkartii—has a karyotype pattern different from those of the rhizomatous tetraploids, showing that it is not likely the genome donor of the tetraploids and the non-monophyletic nature of the section Rhizomatosae. Thus, the tetraploid species should be excluded from the R genome, which should remain exclusively for A. burkartii. Instead, the karyotype features of these tetraploids are compatible with those of different species of the sections Erectoides and Procumbentes (E genome species), suggesting the hypothesis of multiple origins of these tetraploids. In addition, the polyploid nature and the group of diploid species closer to the tetraploids are discussed.     

Species complex delimitation and patterns of population structure at different geographic scales in Neotropical silver catfish (<Emphasis Type="Italic">Rhamdia</Emphasis>: Heptapteridae)

The Neotropical catfish genus Rhamdia inhabits rivers and lakes from Mexico to Argentina. Previous studies have found that the taxonomy of this genus, as well as that of R. quelen, remains controversial. The present study aims to contribute to the understanding of Rhamdia systematics by delimiting putative species, and to elucidate the pattern of genetic differentiation of Rhamdia at different geographic levels within the cis-andean region. Species boundaries were defined by Generalized Mixed Yule Coalescent and Automatic Barcode Gap Discovery methods, and by phylogenetic analyses of cytochrome b (cyt b) sequences. Moreover, we performed phylogeographic analyses based on cyt b sequences and microsatellite markers. Patterns of differentiation were analyzed at three nested geographic levels: in the main cis-andean basins (macrogeographic scale); in the second major Neotropical basin system (mesogeographic scale), which encompasses La Plata basin, Patos-Merin basin, and the coastal lagoons draining to SW Atlantic Ocean; and finally, in the three most important coastal lagoons for artisanal fisheries in Uruguay (microgeographic scale). Sixteen species were found within Rhamdia, divided into two clades (cis- and trans-andean clades), each composed of eight putative species. Cis-andean Rhamdia species have probably diverged due to vicariance events occurring between and within basins since late Miocene-Pleistocene. Microgeographic scale analysis based on cyt b and microsatellite data revealed a high genetic structuring among the studied coastal lagoons. Mitochondrial and microsatellite markers enabled to identify three different populations, corresponding to the three coastal lagoons analyzed, which would have diverged recently and could be considered as different Management Units.     

Contribution of the National Mycology Laboratory Network to Surveillance of Cryptococcosis in Argentina

Purpose of Review

Cryptococcal meningitis is the most common fungal infection of the central nervous system and the third most frequent neurological complication in AIDS patients. To understand the Argentinean epidemiology of cryptococcosis, several efforts have been made by the National Reference Laboratory in Clinical Mycology.

Recent Findings

In Argentina, reports of distribution and frequency of Cryptococcus neoformans and Cryptococcus gattii isolates are scarce and very little is known about its circulating genotypes and mating types. The National Mycology Laboratory Network and the National Reference Laboratory in Clinical Mycology joined forces to estimate the prevalence of cryptococcosis and to obtain and to analyse epidemiological data of this important fungal infection.

Summary

Data presented here were recovered from 1998 to 2016 and represents an approximation to the actual situation of cryptococcosis in Argentina. These results could be useful to design future investigations.

     

Ability of <Emphasis Type="Italic">Lactobacillus fermentum</Emphasis> to overcome host α-galactosidase deficiency,as evidenced by reduction of hydrogen excretion in rats consuming soya α-galacto-oligosaccharides

Background  

Soya and its derivatives represent nutritionally high quality food products whose major drawback is their high content of α-galacto-oligosaccharides. These are not digested in the small intestine due to the natural absence of tissular α-galactosidase in mammals. The passage of these carbohydrates to the large intestine makes them available for fermentation by gas-producing bacteria leading to intestinal flatulence. The aim of the work reported here was to assess the ability of α-galactosidase-producing lactobacilli to improve the digestibility of α-galacto-oligosaccharides in situ.     

Structural insights into hydroxycoumarin-induced apoptosis in U-937 cells

In the present study, we sought to establish the effect of diverse structural-related hydroxycoumarins on the proliferation, cytotoxicity, and induction of apoptosis in promonocytic leukemic cells (U-937). The dihydroxylated coumarins, 7,8-dihydroxy-coumarin and esculetin, induced DNA fragmentation as well as characteristic morphological changes of programmed cell death in U-937 cells. With the aim to perform a structure-activity relationship study, the correlation between the physicochemical properties of the molecules and their pro-apoptotic activity was carried out. Results showed that the presence of two adjacent phenolic hydroxyl groups was the most important factor in terms of the SAR. The exposure of leukemic cells to 7,8-dihydroxy-coumarin evoked a phenoxyl radical generation that was detected by electron spin resonance spectroscopy. The present study suggests that reactive oxygen species generation plays a critical role in dihydroxycoumarin-induced apoptosis in U-937 cells. These findings further suggest that these compounds may have a potential therapeutic role in the treatment of hematological malignancies.     

Influence of 6- or 8-substitution on the antiviral activity of 3-arylalkylthiomethylimidazo[1,2-a]pyridine against human cytomegalovirus (CMV) and varicella-zoster virus (VZV): part II

The synthesis of original imidazo[1,2-a]pyridines bearing a thioether side chain at the 3 position and diversely substituted on the 6 or 8 position, and their antiviral activities are reported. From the synthesized compounds, the imidazo[1,2-a]pyridines bearing a 5 membered heterocycle (thiophene, furane or pyrrole) in the 6 position or a phenylthio group in the 6 or 8 position were the most potent against human cytomegalovirus (CMV) and varicella-zoster virus (VZV), whereas several other congeners, while less potent, were more selective in their inhibitory activity against VZV and CMV. These compounds showed similar activity against thymidine kinase competent (TK+) and deficient (TK-) VZV strains, demonstrating a mechanism of action independent of the viral thymidine kinase.     

Isolation and characterization of a dual function protein from Allium sativum bulbs which exhibits proteolytic and hemagglutinating activities.

A dual function protein was isolated from Allium sativum bulbs and was characterized. The protein had a molecular mass of 25-26 kDa under non-reducing conditions, whereas two polypeptide chains of 12.5+/-0.5 kDa were observed under reducing conditions. E-64 and leupeptin inhibited the proteolytic activity of the protein, which exhibited characteristics similar to cysteine peptidase. The enzyme exhibited substrate specificity and hydrolyzed natural substrates such as alpha-casein (K(m): 23.0 microM), azocasein, haemoglobin and gelatin. It also showed a high affinity for synthetic peptides such as Cbz-Ala-Arg-Arg-OMe-beta-Nam (K(m): 55.24 microM, k(cat): 0.92 s(-1)). The cysteine peptidase activity showed a remarkable stability after incubation at moderate temperatures (40-50 degrees C) over a pH range of 5.5-6.5. The N-terminus of the protein displayed a 100% sequence similarity to the sequences of a mannose-binding lectin isolated from garlic bulbs. Moreover, the purified protein was retained in the chromatographic column when Con-A Sepharose affinity chromatography was performed and the protein was able to agglutinate trypsin-treated rabbit red cells. Therefore, our results indicate the presence of an additional cysteine peptidase activity on a lectin previously described.