Limits of detection of a total reflection x-ray fluorescence system with double reflection module

An X-ray tube with a Mo target and Zr filter, operated at 45 kV/20 mA, was used to excite samples (5 ΜL deposited on a quartz support) and the total reflection angle condition was obtained with a double reflector module built with two 10-cm-long 7-mm-thick quartz crystals placed 50 Μm apart. A high-resolution spectrometer based on a Si(Li) detector coupled to a multichannel analyzer was used for X-ray detection and the spectra were interpreted with the AXIL software. The system was calibrated with standard chemical solutions containing Cr, Fe, Cu, Zn, and Pb, and Y was used as an internal standard to correct eventual geometric errors and high-voltage instabilities of the X-ray generator. The limits of detection were 19, 9, 5, and 4 ng/mL for Cr, Fe, Cu, and Zn, respectively, analyzed through characteristicKk _α X-rays, and 7 ng/mL for Pb, throughLk _α X-rays, considering 50 ΜL samples deposited and dried on a quartz support, to be excited/ detected for 1000 s.     

Development of germ cell transplants: morphometric and ultrastructural studies.

Mouse-to-mouse transplants were studied at 10 min, 9 h, 24 h, 1 week, 1 month, 2 months, and 3 months post-transplantation. Data from a previous light microscope study were confirmed and extended using morphometric and ultrastructural techniques. As soon as 10 min after introduction of the germ cells from one mouse into the tubule lumen of a recipient mouse they developed relationships with small Sertoli cell processes. The extent of this surface-to-surface relationship increased in animals sacrificed up to 1 week post-transplantation. Most transplanted germ cells retained the characteristics of the donor germ cells after they had been isolated and pelleted. Nearly all transplanted cells eventually underwent phagocytosis by the recipient Sertoli cells. The presence of small apparent clones of germ cells after 1 week of transplantation indicated that some germ cells may divide and survive for short periods within the epithelium. No discernible qualitative subcellular changes in the host Sertoli cell accompanying the development of transplant spermatogenesis were noted. Macrophages were present in the region of the boundary tissue between myoid cells and appeared to increase in number in the peritubular tissue of transplanted testes. Images suggest that they migrated into the tubule to gain entrance to the lumen and there take on the form of activated macrophages. Some macrophages phagocytose sperm at 2 months and 3 months post-transplantation. A testis weight increase previously demonstrate to occur at 24 h post-introduction of germ cells was found to be due to an increase in the volume of the tubular lumen. The increase of lumen size at 24 h was not related to the volume of the injected material. It is suggested that the presence of injected cells, likely germ cells, in the tubule lumen stimulated increased secretion by the Sertoli cell.     

Effects of essential oils on biological attributes of Trichogramma galloi adults

Bioactivity of nine essential oils (EOs) was studied on Anagasta kuehniella eggs in relation to the longevity of females, parasitism and emergence rates and sex ratio in the generations parental, F₁ and F₂ of Trichogramma galloi in comparison to a trade formulation of Azadirachta indica. There was no F₁ and F₂ progeny with Zingiber officinale being the most harmful. The greatest reductions in the parasitism rates (57, 43 and 28%) in the parental generation was caused by Allium sativum, Carapa guianensis and A. indica, respectively. In addition, A. sativum reduced the longevity (4.7 days) in the parental generation and emergence (33%) of F₁. Tested EOs did not affect the sex ratio in the generations F₁ and F₂ and emergence in the F₂. Allium sativum and Z. officinale were non-selective to T. galloi; while A. indica, C. guianensis and P. nigrum oils may compromise the progeny; therefore, their use must be avoided. Citrus sinensis, Mentha piperita, Origanum vulgare, Syzygium aromaticum and Thymus vulgare were selective to T. galloi, and these EOs are promising for IPM programs.     

In Vivo and in Silico Trypanocidal Activity Evaluation of (−)-Cubebin Encapsulated in PLGA Microspheres as Potential Treatment in Acute Phase

In this study, the trypomastigotes of a Y strain of Trypanosoma cruzi were inoculated intraperitoneally into male BALB/c mice weighing approximately 25 g each, which were divided into groups for evaluation of the trypanocidal activity. For the treatment of experimental groups, encapsulated and unencapsulated (−)-cubebin, Benznidazole, and two groups as negative controls were used. The encapsulated (−)-cubebin showed a 68.1 % encapsulation efficiency. The parasitemia peak of substances remained around the 9^th day after the observed reduction in the number of circulating trypomastigotes. The encapsulated (−)-cubebin and (−)-cubebin unloaded showed a decrease of 61.3 % and 58.5 % in the number of parasites as compared to the negative control, respectively. Moreover, animals treated with encapsulated (−)-cubebin had a higher survival time as compared to the other groups. In conclusion, the results obtained were more promising for encapsulated (−)-cubebin as compared to unloaded particles.     

Long non-coding RNA INXS is a critical mediator of BCL-XS induced apoptosis

BCL-X mRNA alternative splicing generates pro-apoptotic BCL-XS or anti-apoptotic BCL-XL gene products and the mechanism that regulates splice shifting is incompletely understood. We identified and characterized a long non-coding RNA (lncRNA) named INXS, transcribed from the opposite genomic strand of BCL-X, that was 5- to 9-fold less abundant in tumor cell lines from kidney, liver, breast and prostate and in kidney tumor tissues compared with non-tumors. INXS is an unspliced 1903 nt-long RNA, is transcribed by RNA polymerase II, 5′-capped, nuclear enriched and binds Sam68 splicing-modulator. Three apoptosis-inducing agents increased INXS lncRNA endogenous expression in the 786-O kidney tumor cell line, increased BCL-XS/BCL-XL mRNA ratio and activated caspases 3, 7 and 9. These effects were abrogated in the presence of INXS knockdown. Similarly, ectopic INXS overexpression caused a shift in splicing toward BCL-XS and activation of caspases, thus leading to apoptosis. BCL-XS protein accumulation was detected upon INXS overexpression. In a mouse xenograft model, intra-tumor injections of an INXS-expressing plasmid caused a marked reduction in tumor weight, and an increase in BCL-XS isoform, as determined in the excised tumors. We revealed an endogenous lncRNA that induces apoptosis, suggesting that INXS is a possible target to be explored in cancer therapies.     

Proteomic and functional analyses reveal a unique lifestyle for Acinetobacter baumannii biofilms and a key role for histidine metabolism

Biofilm formation is one of the main causes for the persistence of Acinetobacter baumannii, a pathogen associated with severe infections and outbreaks in hospitals. Here, we performed comparative proteomic analyses (2D-DIGE and MALDI-TOF/TOF and iTRAQ/SCX-LC-MS/MS) of cells at three different conditions: exponential, late stationary phase, and biofilms. These results were compared with alterations in the proteome resulting from exposure to a biofilm inhibitory compound (salicylate). Using this multiple-approach strategy, proteomic patterns showed a unique lifestyle for A. baumannii biofilms and novel associated proteins. Several cell surface proteins (such as CarO, OmpA, OprD-like, DcaP-like, PstS, LysM, and Omp33), as well as those involved in histidine metabolism (like Urocanase), were found to be implicated in biofilm formation, this being confirmed by gene disruption. Although l-His uptake triggered biofilms efficiently in wild-type A. baumannii, no effect was observed in Urocanase and OmpA mutants, while a slight increase was observed in a CarO deficient strain. We conclude that Urocanase plays a crucial role in histidine metabolism leading to biofilm formation and that OmpA and CarO can act as channels for L-His uptake. Finally, we propose a model in which novel proteins are suggested for the first time as targets for preventing the formation of A. baumannii biofilms.     

Age-related differences in time-limit performance and force platform-based balance measures during one-leg stance

Poor posture control has been associated with an increased risk of falls and mobility disability among older adults. This study was conducted to assess the test–retest reliability and sensitivity to group differences regarding the time-limit (T_Limit) of one-leg standing and selected balance parameters obtained with a force platform in older and young adults. A secondary purpose was to assess the relationship between T_Limit and these balance parameters. Twenty-eight healthy older adults (age: 69 ± 5 years) and thirty young adults (age: 21 ± 4 years) participated in this study. Two one-leg stance tasks were performed: (1) three trials of 30 s maximum and (2) one T_Limit trial. The following balance parameters were computed: center of pressure area, RMS sway amplitude, and mean velocity and mean frequency in both the anterio-posterior and medio-lateral directions. All balance parameters obtained with the force platform as well as the T_Limit variable were sensitive to differences in balance performance between older and young adults. The test–retest reliability of these measures was found to be acceptable (ICC: 0.40–0.85), with better ICC scores observed for mean velocity and mean frequency in the older group. Pearson correlations coefficients (r) between balance parameters and T_Limit ranged from ?0.16 to ?0.54. These results add to the current literature that can be used in the development of measurement tools for evaluating balance in older and young adults.     

Adenosine A2A receptor activation is determinant for BDNF actions upon GABA and glutamate release from rat hippocampal synaptosomes

Adenosine, through A_2A receptor (A_2AR) activation, can act as a metamodulator, controlling the actions of other modulators, as brain-derived neurotrophic factor (BDNF). Most of the metamodulatory actions of adenosine in the hippocampus have been evaluated in excitatory synapses. However, adenosine and BDNF can also influence GABAergic transmission. We thus evaluated the role of A_2AR on the modulatory effect of BDNF upon glutamate and GABA release from isolated hippocampal nerve terminals (synaptosomes). BDNF (30 ng/ml) enhanced K⁺-evoked [³H]glutamate release and inhibited the K⁺-evoked [³H]GABA release from synaptosomes. The effect of BDNF on both glutamate and GABA release requires tonic activation of adenosine A_2AR since for both neurotransmitters, the BDNF action was blocked by the A_2AR antagonist SCH 58261 (50 nM). In the presence of the A_2AR agonist, {"type":"entrez-protein","attrs":{"text":"CGS21680","term_id":"878113053","term_text":"CGS21680"}}CGS21680 (30 nM), the effect of BDNF on either glutamate or GABA release was, however, not potentiated. It is concluded that both the inhibitory actions of BDNF on GABA release as well as the facilitatory action of the neurotrophin on glutamate release are dependent on the activation of adenosine A_2AR by endogenous adenosine. However, these actions could not be further enhanced by exogenous activation of A_2AR.     

Polarity of microtubules nucleated by centrosomes and chromosomes of Chinese hamster ovary cells in vitro

The structural and growth polarities of centrosomal and chromosomal microtubules were studied by analyzing the kinetics of growth of these microtubules and those initiated by flagellar seeds. By comparing rates of elongation of centrosomal and flagellar-seeded microtubules, we determined whether the centrosomal microtubules were free to grow at their plus ends only, minus ends ony, or at both ends. Our results show that centrosomal microtubules elongate at a rate corresponding to the addition of subunits at the plus end only. The depolymerization rate was also equivalent to that for the plus end only. Chromosomal microtubule elongation was similar to the centrosome-initiated growth. Since the data do not support the hypothesis that both ends of these spindle microtubules are able to interact with monomer in solution, then growth must occur only distal or only proximal to the organizing centers, implying tha the opposite ends in unavailable for exchange of subunits. Experiments with flagellar-seeded microtubules serving as internal controls indicated that the inactivity of the minus end could not be accounted for by a diffusible inhibitor, suggesting a structural explanation. Since there is no apparent way in which the distal ends may be capped, whereas the proximal ends are embedded in the pericentriolar cloud, we conclude that centrosomal microtubules are oriented with their plus ends distal to the site of nucleation. A similar analysis for chromosomal microtubules suggests that they too must be oriented with their plus ends distal to the site of initiation.     

Ultrastructure of the germ cells in the testis of matrinxã, Brycon cephalus (Teleostei, Characidae)

This study describes at ultrastructural level the germ cells in the testis of matrinx? (Brycon cephalus) raised in captivity. The specimens 'matrinx?' were maintained in four breeding tanks of 200 m(2), at the Aquaculture Research Center at Vale do Ribeira-CEPAR, from Fishery Institute, in Pariquera-A?u City, S?o Paulo, Brazil. The samples were collected from March 1994 to February 1996. The testis has been classified as tubular unrestricted spermatogonial type, in which four stages of germ cells can be distinguished as follows: spermatogonia, spermatocytes (primary and secondary); spermatids and spermatozoa.