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.

Isolation and acetylation of cellulose nanostructures with a homogeneous system.

A homogeneous system for nanocellulose acetylation was investigated. Cellulose nanostructures (CNS) were obtained from microcrystalline cellulose, and modification was conducted to increase hydrophobicity and physico-chemical properties of the nanoparticles. Sulfuric acid and hydrochloric acid were used for the isolation. The CNS were characterized with dynamic light scattering, zeta potential, atomic force microscopy, Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray photoelectron spectrometry, degree of substitution (DS), X-ray diffraction (XRD), and thermogravimetric analysis. Nanostructures obtained with sulfuric acid showed lower particle sizes and lower thermal stability. After modification, the results indicated the substitution of OH groups in cellulose structure by acetyl groups. The XRD patter was considerably modified and it was verified that acetylation increased the thermal stability. Different methods were used to calculate the DS, and the differences between the methodologies were explained. The acetylated samples play an important role in the nanocomposites field, since the hydrophobic surface increase its applications.

X-ray powder diffraction and other analyses of cellulose nanocrystals obtained from corn straw by chemical treatments.

The extraction of nanocellulose from agro-industrial wastes is feasible due to a significant amount of cellulose contained in these natural fibers. The analysis of chemical treatments effects on the fibers to obtain the nanocellulose must be taken into consideration for the definition of an adequate and efficient methodology. In this study, two alkaline treatments were used (cleaning and bleaching), as well as an acid treatment for the extraction of nanocellulose from corn straw residues. The samples were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), dynamic light scattering (DLS) and atomic force microscopy (AFM) to verify the action and modifications caused in their chemical and physical structures. It was possible to verify the extraction of hemicellulose and lignin, the reduction of fiber sizes to the nanoscale, and the final sample presenting superior crystallinity for the bleached fiber.

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.

Clinical results of excimer laser photorefractive keratectomy: a multicenter study of 265 eyes.

Efficacy, predictability, and safety of excimer laser photorefractive keratectomy were evaluated at centers in Paris and Brest, France. Photoablation was performed with the VISX laser on 265 eyes (151 at the Paris center and 114 at the Brest center). The eyes were clinically and statistically evaluated over a six month follow-up. Initial myopia ranged from -0.7 to -19.4 diopters (D) (mean spherical equivalent [SE] -5.9 D) in the Paris center and from -0.9 to -14.5 D (SE -4.5 D) in the Brest center. At both centers, the mean uncorrected visual acuity was worse than 20/200; over 90% of cases in each center had a best uncorrected visual acuity of 20/100 or worse. Results are reported globally and for subgroups of myopia: Group A, SE better than or equal to -3.0 D; Group B, SE worse than -3.0 D and better than or equal to -7.0 D; Group C, SE worse than -7.0 D. Uncorrected visual acuity was significantly improved in the patients followed for six months; 64% of Paris cases and 62% of Brest cases obtained an uncorrected visual acuity of 20/40 or better. Predictability of the treatment was good; 67% of Paris eyes and 74% of Brest eyes were less than 1.0 D from the intended correction after six months. The data suggest that the initial myopia affected the efficacy and predictability of the treatment; results in the mild to moderate myopia eyes were significantly better than results in the severe myopia eyes. One case of visual acuity regression (less than one line) was observed in the two groups. This was associated with corneal haze of moderate intensity.

Effect of preoperative YAG laser anterior capsulotomy on the incidence of posterior capsule opacification: ten year follow-up.

One hundred twenty-two patients, who were followed for ten years, had bilateral extracapsular cataract surgery with implantation of J-looped posterior chamber lenses between 1980 and 1981. On the first eye an anterior capsulotomy was performed with a pico-second YAG laser 12 to 20 hours before surgery; on the second eye a capsulotomy was performed manually at the time of surgery. Four of the eyes (3.27%) with laser capsulotomies had opacified posterior capsules after ten years; 61 of the eyes (50.00%) with manual capsulotomies had opacified capsules that had to be opened with a YAG laser.

One-movement insertion of the superior loop into the bag.

An efficient, simple technique for one-movement insertion of the superior intraocular lens loop into the capsular bag is described. This bimanual technique avoids undue stress on the capsular bag and zonules, may be used with all extracapsular techniques, and is suitable for almost all flexible loop intraocular lenses designed for in-the-bag implantation.

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.

Corneal wound healing after excimer laser keratotomy in a human eye.

A pulsed excimer argon-fluorine laser was used to produce corneal incisions in vivo in a human cornea. Fourteen days after the laser surgery, the incisions were examined by light and transmission electron microscopy. There was good initial healing, with no inflammatory or immune reactions in the incisions.

Excimer laser surgery of the cornea: qualitative and quantitative aspects of photoablation according to the energy density.

Using an excimer laser working in the far ultraviolet and cutting fresh corneas of human cadaver eyes, we were able to demonstrate that there is an ideal fluence (joule/cm2/pulse) that allows a maximum tissue ablation depth per shot. Above the threshold of 1 J/cm2/pulse the depth of tissue ablated does not increase and both thermal and mechanical damage appears at the cut edges.

Influence of picosecond and nanosecond YAG laser capsulotomy on intraocular pressure.

To evaluate laser-induced intraocular pressure rise with three YAG lasers, I performed posterior capsulotomies on three groups of patients. Each group contained 100 nonglaucomatous patients who had extracapsular cataract extraction with and without lens implantation. In each group 50 patients were treated with prophylactic medications. The three YAG lasers were (1) a picosecond TEMoo, mode locked, ten-degree cone angle; (2) a nanosecond TEMoo, Q-switched, 16-degree cone angle, delivering the energy in five nanoseconds per pulse; and (3) a Q-switched, 15-degree cone angle, closer to multimode than TEMoo, delivering energy in 14 nanoseconds seconds per pulse. The energy delivered per pulse, the thickness of the lens material, the shape (mode) of the pulse, the optical delivery system, and the width of the shock wave appear to act on intraocular pressure and to be factors influencing the possibility of marking the lens.

Use of a pulsed picosecond Nd: YAG laser in 6,664 cases.

We used a modulated picosecond Nd:YAG laser to perform preoperative anterior capsulotomies and posterior capsulotomies in eyes with and without an intraocular lens, and to cut a variety of cyclitic membranes, iridocapsular adhesions, and vitreous traction bands in more than 6,500 cases. The complications were transient bleeding when vascularized tissues were cut because the laser does not coagulate, temporary anterior chamber inflammation, and transient increased intraocular pressure. The last two were caused by released lens material and shock wave side effects.