Innovative process for obtaining modified nanocellulose from soybean straw

In the present research, soybean straw was used to prepare nanocellulose (NC) via a ball mill, in different milling times (6, 9, and 12 h) and in-situ modified with an anionic surfactant. NCs were characterized for their chemical structure, surface composition, dimension and stability, morphology, crystalline structure, and thermal stability. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicated a cellulosic structure for NCs and a physical interaction due to the electronic attractions between nanocellulose hydroxyls and surfactant end chain groups. The dynamic light scattering, Zeta potential, and transmission electron microscopy indicated that the in situ modified samples showed smaller sizes and good electrostatic stability. Besides, while ball mill resulted in nanofibers, the in situ modified-NC showed a nanocrystal shape, indicating that the surfactant alters the milling process and cellulose scale reduction. The modified-NC showed lower crystallinity and crystal size than unmodified nanocelluloses due to the surfactant chains' addition and influence during the milling process. The modified-NC showed slightly superior thermal stability. The NC-12S showed smaller particle sizes, high electrostatic, and thermal stability and indicated that 12 h is adequate to prepare modified nanocellulose via in situ modification. The prepared samples could be potentially used as coatings, emulsifiers, and nanocomposites reinforcing agents.

An effective CTL peptide vaccine for Ebola Zaire Based on Survivors' CD8+ targeting of a particular nucleocapsid protein epitope with potential implications for COVID-19 vaccine design

The 2013-2016 West Africa EBOV epidemic was the biggest EBOV outbreak to date. An analysis of virus-specific CD8+ T-cell immunity in 30 survivors showed that 26 of those individuals had a CD8+ response to at least one EBOV protein. The dominant response (25/26 subjects) was specific to the EBOV nucleocapsid protein (NP). It has been suggested that epitopes on the EBOV NP could form an important part of an effective T-cell vaccine for Ebola Zaire. We show that a 9-amino-acid peptide NP44-52 (YQVNNLEEI) located in a conserved region of EBOV NP provides protection against morbidity and mortality after mouse adapted EBOV challenge. A single vaccination in a C57BL/6 mouse using an adjuvanted microsphere peptide vaccine formulation containing NP44-52 is enough to confer immunity in mice. Our work suggests that a peptide vaccine based on CD8+ T-cell immunity in EBOV survivors is conceptually sound and feasible. Nucleocapsid proteins within SARS-CoV-2 contain multiple Class I epitopes with predicted HLA restrictions consistent with broad population coverage. A similar approach to a CTL vaccine design may be possible for that virus.

Serotonin actions within the prelimbic cortex induce anxiolysis mediated by serotonin 1a receptors

BACKGROUND:

Serotonin plays an important role in the regulation of anxiety, acting through complex modulatory mechanisms within distinct brain structures. Serotonin can act through complex negative feedback mechanisms controlling the neuronal activity of serotonergic circuits and downstream physiologic and behavioral responses. Administration of serotonin or the serotonin 1A receptor agonist, (±)-8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT), into the prefrontal cortex, inhibits anxiety-like responses. The prelimbic area of the prefrontal cortex regulates serotonergic neurons within the dorsal raphe nucleus and is involved in modulating anxiety-like behavioral responses.

AIMS:

This study aimed to investigate the serotonergic role within the prelimbic area on anxiety- and panic-related defensive behavioral responses.

METHODS:

We investigated the effects of serotonin within the prelimbic area on inhibitory avoidance and escape behaviors in the elevated T-maze. We also extended the investigation to serotonin 1A, 2A, and 2C receptors.

RESULTS:

Intra-prelimbic area injection of serotonin or 8-OH-DPAT induced anxiolytic effects without affecting escape behaviors. Previous administration of the serotonin 1A receptor antagonist, WAY-100635, into the prelimbic area counteracted the anxiolytic effects of serotonin. Neither the serotonin 2A nor the serotonin 2C receptor preferential agonists, (±)-2,5-dimethoxy-4-iodoamphetamine (DOI) and 6-chloro-2-(1-piperazinyl) pyrazine (MK-212), respectively, affected behavioral responses in the elevated T-maze.

CONCLUSION:

Facilitation of serotonergic signaling within the prelimbic area of rats induced an anxiolytic effect in the elevated T-maze test, which was mediated by local serotonin 1A receptors. This inhibition of anxiety-like defensive behavioral responses may be mediated by prelimbic area projections to neural systems controlling anxiety, such as the dorsal raphe nucleus or basolateral amygdala.

Control of pathogenic CD8+ T cell migration to the brain by IFN-gamma during experimental cerebral malaria

Previous studies have shown that IFN-gamma is essential for the pathogenesis of cerebral malaria (CM) induced by Plasmodium berghei ANKA (PbA) in mice. However, the exact role of IFN-gamma in the pathway (s) leading to CM has not yet been described. Here, we used 129P2Sv/ev mice which develop CM between 7 and 14 days post-infection with PbA. In this strain, both CD4(+) and CD8(+) T cells were involved in the effector phase of CM. When 129P2Sv/ev mice deficient in the IFN-gamma receptor alpha chain (IFN-gammaR1) were infected with PbA, CM did not occur. Migration of leucocytes to the brain at the time of CM was observed in wild type (WT) but not in deficient mice. However, in the latter, there was an accumulation of T cells in the lungs. Analysis of chemokines and their receptors in WT and in deficient mice revealed a complex, organ-specific pattern of expression. Up-regulation of RANTES/CCL5, IP-10/CCL3 and CCR2 was associated with leucocyte migration to the brain and increased expression of MCP-1/CCL2, IP-10/CCL3 and CCR5 with leucocyte migration to the lung. This shows that IFN-gamma controls trafficking of pathogenic T cells in the brain, thus providing an explanation for the organ-specific pathology induced by PbA infection.

Reservosome: an endocytic compartment in epimastigote forms of the protozoan Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae). Correlation between endocytosis of nutrients and cell differentiation

Reservosomes are large membrane-bound organelles found at the posterior end of epimastigote forms of Trypanosoma cruzi, but absent in amastigotes and trypomastigotes. We have transferred bloodstream trypomastigotes to LIT medium supplemented with gold-labelled transferrin in order to analyse, at the ultrastructural level, the occurrence of reservosomes and endocytosis during the trypomastigote to epimastigote differentiation. After 24 h, the trypomastigotes differentiated into amastigotes, which adhered to each other forming large clusters. Electron-dense vesicles were detected close to the Golgi complex in cells with intermediary characteristics between amastigotes and epimastigotes, but typical reservosomes at the posterior cell tip were still absent. Transferrin-gold complexes were observed only bound to the surface of clustered cells. After 72 h, epimastigotes were observed being released from the clusters and free-swimming epimastigotes appeared, containing electron-dense vesicles at their posterior region. Typical reservosomes, labelled with transferrin-gold, were observed only in free-swimming epimastigotes. When fully differentiated epimastigotes were incubated with transferrin-gold complexes and then processed for the immunocytochemical detection of cysteine proteinase, all reservosomes were positive for the enzyme, but co-localization of both markers did not occur in all organelles. Our data demonstrate that in T. cruzi epimastigotes endocytosis is strongly related to reservosome biogenesis during the trypomastigote to epimastigote differentiation process.

Excretory-secretory antigens of Trypanosoma cruzi are potentially useful for serodiagnosis of chronic Chagas' disease

The reactivities of sera from chronic chagasic patients against the trypomastigote excreted-secreted antigens (TESA) of Trypanosoma cruzi strains with different biodemes were analyzed by TESA-blot and TESA-enzyme-linked immunosorbent assay (ELISA). Although both tests presented high sensitivity and specificity, TESA-ELISA is more appropriate for screening a larger number of samples.

Serodiagnosis of chronic Chagas infection by using EIE-Recombinant-Chagas-Biomanguinhos kit

A kit based on an enzyme immunoassay, EIE-Recombinant-Chagas-Biomanguinhos, developed by the Oswaldo Cruz Foundation, was evaluated for the serodiagnosis of chronic Chagas disease. Evaluation was performed with 368 serum samples collected from individuals living in an endemic area for Chagas disease: 131 patients in the chronic phase with confirmed clinical, epidemiological, and serological diagnosis (indirect immunofluorescence, indirect hemagglutination or enzyme-linked immunosorbent assay) and 237 nonchagasic seronegative individuals were considered negative control. The EIE-Recombinant-Chagas-Biomanguinhos kit showed high sensitivity, 100% (CI 95%: 96.4-100%) and high specificity, 100% (CI 95%: 98-100%). The data obtained were in full agreement with clinical and conventional serology data. In addition, no cross-reaction was observed with sera from patients with cutaneous (n=14) and visceral (n=3) leishmaniasis. However, when these sera were tested by conventional serological assays for Chagas disease, cross-reactions were detected in 14.3% and 33.3% of the patients with cutaneous and visceral leishmaniasis, respectively. No cross-reactions were observed when sera from nonchagasic seronegative patients bearing other infectious disease (syphilis, n=8; HTLV, n=8; HCV, n=7 and HBV, n=12) were tested. In addition, sera of patients with inconclusive results for Chagas disease by conventional serology showed results in agreement with clinical evaluation, when tested by the kit. These results are relevant and indicate that the referred kit provides a safe immunodiagnosis of Chagas disease and could be used in blood bank screening.

Differentiation of Trypanosoma cruzi epimastigotes: metacyclogenesis and adhesion to substrate are triggered by nutritional stress

Differentiation of Trypanosoma cruzi epimastigotes to metacyclic trypomastigotes occurs in the insect rectum, after adhesion of the epimastigotes to the intestinal wall. We investigated the effect of the nutritional stress on the metacyclogenesis process in vitro by incubating epimastigotes in the chemically defined TAU3AAG medium supplemented with different nutrients. Addition of fetal bovine serum induced epimastigote growth but inhibited metacyclogenesis. In this medium, few parasites attached to the substrate. Ultrastructural analysis demonstrated reservosomes at the posterior end of the epimastigotes. Incubation of the cells in TAU3AAG medium containing gold-labeled transferrin resulted in high endocytosis of the marker by both adhered and free-swimming epimastigotes. No intracellular gold particles could be detected in trypomastigotes. Addition of transferrin gold complexes to adhered epimastigotes cultivated for 4 days in TAU3AAG medium resulted in decrease of both metacyclogenesis and adhesion to the substrate, as compared with parasites maintained in transferrin-free medium. Adhesion to the substrate is triggered by nutritional stress, and proteins accumulated in reservosomes are used as energy source during the differentiation. A close relationship exists among nutritional stress, endocytosis of nutrients, adhesion to the substrate, and cell differentiation in T. cruzi epimastigotes.

Laser in situ keratomileusis for hyperopia

OBJECTIVE

To evaluate laser in situ keratomileusis (LASIK) ablation zone size and its relationship to refractive and visual outcomes in the treatment of hyperopia.

METHODS

We evaluated retrospectively 40 eyes of 20 patients who had LASIK: 20 eyes had a refractive ablation zone ranging from 5.5 to 9.0 mm (Group 1); Group 2 consisted of 20 eyes with a refractive ablation zone from 5.5 to 8.25 mm. We used the Nidek EC-5000 excimer laser and the Hansatome microkeratome. Mean spherical equivalent refraction was +2.72 D in Group 1 and +2.75 D in Group 2. Objective refraction and visual acuity were evaluated over 6 months in both groups.

RESULTS

Six months after LASIK, mean spherical equivalent refraction in Group 1 was +1.00 +/- 0.84 D and in Group 2 it was +0.75 +/- 0.42 D. One patient in Group 1 lost 1 line of spectacle-corrected visual acuity; none in Group 2 lost lines. Six patients gained 1 to 3 lines from their preoperative spectacle-corrected visual acuity.

CONCLUSIONS

LASIK provides good results for mild and moderate hyperopia. LASIK with an ablation zone from 5.5 to 8.25 mm showed better predictability and more stable results. However, corneal diameter and the thickness and width of the flap appear to be important factors in the feasibility of LASIK in hyperopic eyes.

Wound healing following excimer laser radial keratotomy

A pulsed excimer laser was used to produce radial keratotomy in vivo in human corneas and the wound healing process was studied. Fluences of 370 mJ/cm2 at a repetition rate of 20 Hz were effective and atraumatic. The wound healing process was remarkably uneventful without an inflammatory or immune reaction apparent at 21 days. Consistent flattening of the cornea was obtained by shallower cuts than with conventional radial keratotomy techniques.