Insights into the action of phylogenetically diverse microbial expansins on the structure of cellulose microfibrils

BACKGROUND

Microbial expansins (EXLXs) are non-lytic proteins homologous to plant expansins involved in plant cell wall formation. Due to their non-lytic cell wall loosening properties and potential to disaggregate cellulosic structures, there is considerable interest in exploring the ability of microbial expansins (EXLX) to assist the processing of cellulosic biomass for broader biotechnological applications. Herein, EXLXs with different modular structure and from diverse phylogenetic origin were compared in terms of ability to bind cellulosic, xylosic, and chitinous substrates, to structurally modify cellulosic fibrils, and to boost enzymatic deconstruction of hardwood pulp.

RESULTS

Five heterogeneously produced EXLXs (Clavibacter michiganensis; CmiEXLX2, Dickeya aquatica; DaqEXLX1, Xanthomonas sacchari; XsaEXLX1, Nothophytophthora sp.; NspEXLX1 and Phytophthora cactorum; PcaEXLX1) were shown to bind xylan and hardwood pulp at pH 5.5 and CmiEXLX2 (harboring a family-2 carbohydrate-binding module) also bound well to crystalline cellulose. Small-angle X-ray scattering revealed a 20-25% increase in interfibrillar distance between neighboring cellulose microfibrils following treatment with CmiEXLX2, DaqEXLX1, or NspEXLX1. Correspondingly, combining xylanase with CmiEXLX2 and DaqEXLX1 increased product yield from hardwood pulp by ~ 25%, while supplementing the TrAA9A LPMO from Trichoderma reesei with CmiEXLX2, DaqEXLX1, and NspEXLX1 increased total product yield by over 35%.

CONCLUSION

This direct comparison of diverse EXLXs revealed consistent impacts on interfibrillar spacing of cellulose microfibers and performance of carbohydrate-active enzymes predicted to act on fiber surfaces. These findings uncover new possibilities to employ EXLXs in the creation of value-added materials from cellulosic biomass.

Deaggregation of cellulose macrofibrils and its effect on bound water

The purpose of this study was to determine how to control and measure the hierarchical swelling in pulp fibers via electrostatic interactions and localized osmotic pressure. A eutectic solvent system was used to systematically increase phosphate groups in the cell wall. Increase in fiber charge led to an increase in swelling properties, as expected. At a charge value around 180-200 μmol/g the macrofibrils were found to deaggregate. This led to a large jump in mesoscale swelling, from 0.9 to 2.5 mL/g, and surface area, from 400 to 1000 m2/g. This deaggregation was confirmed with X-ray scattering and solute exclusion. A novel thermoporosimetry method was used in the study. This involved splitting the nonfreezing water into two subfractions, thus allowing a more complete analysis of pore structure and surface area. The hydrated surface area for the samples was in the range 1200-1400 m2/g, which agreed well with simulations of aggregated microfibrils. Adding charge to the pulp fibers had a nonlinear effect on handsheet strength properties. This suggests that hierarchical control of fiber swelling may be a useful approach to improve important property pairs such as strength/density in packaging and other commercially important fiber products.

Degradation of cellulose polymorphs into glucose by HCl gas with simultaneous suppression of oxidative discoloration

As cellulose is the main polysaccharide in biomass, its degradation into glucose is a major undertaking in research concerning biofuels and bio-based platform chemicals. Here, we show that pressurized HCl gas is able to efficiently hydrolyze fibers of different crystalline forms (polymorphs) of cellulose when the water content of the fibers is increased to 30-50 wt%. Simultaneously, the harmful formation of strongly chromophoric humins can be suppressed by a simple addition of chlorite into the reaction system. 50-70 % glucose yields were obtained from cellulose I and II polymorphs while >90 % monosaccharide conversion was acquired from cellulose III_II after a mild post-hydrolysis step. Purification of the products is relatively unproblematic from a gas-solid mixture, and a gaseous catalyst is easier to recycle than the aqueous counterpart. The results lay down a basis for future practical solutions in cellulose hydrolysis where side reactions are controlled, conversion rates are efficient, and the recovery of products and reagents is effortless.

Spatioselective surface chemistry for the production of functional and chemically anisotropic nanocellulose colloids

Maximizing the benefits of nanomaterials from biomass requires unique considerations associated with their native chemical and physical structure. Both cellulose nanofibrils and nanocrystals are extracted from cellulose fibers via a top-down approach and have significantly advanced materials chemistry and set new benchmarks in the last decade. One major challenge has been to prepare defined and selectively modified nanocelluloses, which would, e.g., allow optimal particle interactions and thereby further improve the properties of processed materials. At the molecular and crystallite level, the surface of nanocelluloses offers an alternating chemical structure and functional groups of different reactivity, enabling straightforward avenues towards chemically anisotropic and molecularly patterned nanoparticles via spatioselective chemical modification. In this review, we will explain the influence and role of the multiscale hierarchy of cellulose fibers in chemical modifications, and critically discuss recent advances in selective surface chemistry of nanocelluloses. Finally, we will demonstrate the potential of those chemically anisotropic nanocelluloses in materials science and discuss challenges and opportunities in this field.

Effect of Moisture on Polymer Deconstruction in HCl Gas Hydrolysis of Wood

The HCl gas system previously used to produce cellulose nanocrystals was applied on Scots pine wood, aiming at a controlled deconstruction of its macrostructure while understanding the effect on its microstructure. The HCl gas treatments resulted in a well-preserved cellular structure of the wood. Differences in wood initial moisture content (iMC) prior to HCl gas treatment played a key role in hydrolysis rather than the studied range of exposure time to the acidic gas. Higher iMCs were correlated with a higher degradation of hemicellulose, while crystalline cellulose microfibrils were not largely affected by the treatments. Remarkably, the hydrogen-deuterium exchange technique showed an increase in accessible OH group concentration at higher iMCs, despite the additional loss in hemicelluloses. Unrelated to changes in the accessible OH group concentration, the HCl gas treatment reduced the concentration of absorbed D₂O molecules.

Experimental and Simulation Study of the Solvent Effects on the Intrinsic Properties of Spherical Lignin Nanoparticles

Spherical lignin nanoparticles (LNPs) fabricated via nanoprecipitation of dissolved lignin are among the most attractive biomass-derived nanomaterials. Despite various studies exploring the methods to improve the uniformity of LNPs or seeking more application opportunities for LNPs, little attention has been given to the fundamental aspects of the solvent effects on the intrinsic properties of LNPs. In this study, we employed a variety of experimental techniques and molecular dynamics (MD) simulations to investigate the solvent effects on the intrinsic properties of LNPs. The LNPs were prepared from softwood Kraft lignin (SKL) using the binary solvents of aqueous acetone or aqueous tetrahydrofuran (THF) via nanoprecipitation. The internal morphology, porosity, and mechanical properties of the LNPs were analyzed with electron tomography (ET), small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and intermodulation AFM (ImAFM). We found that aqueous acetone resulted in smaller LNPs with higher uniformity compared to aqueous THF, mainly ascribing to stronger solvent–lignin interactions as suggested by MD simulation results and confirmed with aqueous 1,4-dioxane (DXN) and aqueous dimethyl sulfoxide (DMSO). More importantly, we report that both LNPs were compact particles with relatively homogeneous density distribution and very low porosity in the internal structure. The stiffness of the particles was independent of the size, and the Young’s modulus was in the range of 0.3–4 GPa. Overall, the fundamental understandings of LNPs gained in this study are essential for the design of LNPs with optimal performance in applications.

Hyponatremia associates with poor outcome in metastatic renal cell carcinoma patients treated with everolimus: prognostic impact

BACKGROUND

The prognostication of metastatic renal cell carcinoma (mRCC) is based on Memorial Sloan Kettering Cancer Center (MSKCC) and International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk classifications. Research has shown that hyponatremia is associated with worse prognosis in cancer. We analyzed the association of hyponatremia and outcome in everolimus-treated mRCC patients.

PATIENTS AND METHODS

Baseline and on-treatment (≤12 weeks) sodium in 233 mRCC patients was analyzed using Kaplan-Meier, Cox regression and logistic regression. Baseline sodium was correlated with baseline thrombocyte and neutrophil values.

RESULTS

65 (28%) and 41 (18%) patients had sodium < lower limit of normal (LLN) at baseline and on-treatment, respectively. Baseline sodium < LLN was associated with shorter overall survival (OS) (6.1 vs. 10.3 months; p < .001) and progression-free survival (PFS) (2.8 vs. 3.5 months; p = .04). On-treatment sodium < LLN was associated with shorter OS (5.4 vs. 9.9 months; p < .001) and PFS (2.8 vs. 4.0 months; p < .001). In multivariate analyses adjusted for IMDC factors, baseline and on-treatment sodium < LLN were significantly associated with shorter OS (adjusted HR 1.46 (95% CI 1.04-2.05); p = .02; adjusted HR 1.80 (95% CI 1.23-2.61); p = .002; respectively). On-treatment sodium < LLN was significantly associated with progressive disease (OR 0.23 (95% CI 0.10-0.56); p = .001). A landmark analysis demonstrated that on-treatment hyponatremia was significantly associated with shorter OS and PFS (p = .01 and p = .03, respectively). On-treatment normalization of hyponatremia was associated with improved OS (unadjusted HR 0.61 (95% CI 0.35-0.98); p = .04), as compared to patients with sustained hyponatremia throughout follow-up.

CONCLUSIONS

Hyponatremia associates with poor outcome in mRCC patients treated with everolimus. On-treatment normalization of hyponatremia to normal sodium values associates with favorable outcome.

Arthroscopic ultrasound technique for simultaneous quantitative assessment of articular cartilage and subchondral bone: an in vitro and in vivo feasibility study

Traditional arthroscopic examination is subjective and poorly reproducible. Recently, we introduced an arthroscopic ultrasound method for quantitative diagnostics of cartilage lesions. Here we describe our investigation of the feasibility of ultrasound arthroscopy for simultaneous measurements of articular cartilage and subchondral bone. Human osteochondral samples (n = 13) were imaged using a clinical 9-MHz ultrasound system. Ultrasound reflection coefficients (R, IRC), the ultrasound roughness index (URI) and the apparent integrated backscattering coefficient (AIB) were determined for both tissues. Mechanical testing, histologic analyses and micro-scale computed tomography imaging were the reference methods. Ultrasound arthroscopies were conducted on two patients. The ultrasound reflection coefficient correlated with the Mankin score and Young's modulus of cartilage (|r| > 0.56, p < 0.05). Ultrasound parameters (R, IRC, AIB) for subchondral bone correlated with the bone surface/volume ratio (|r| > 0.70, p < 0.05) and trabecular thickness (|r| > 0.59, p < 0.05). Furthermore, R and subchondral bone mineral density were significantly correlated (|r| > 0.65, p < 0.05). Arthroscopic ultrasound examination provided diagnostically valuable information on cartilage and subchondral bone in vivo.

111In-labelled bleomycin complex for the differentiation of high- and low-grade gliomas

The aim of this study was to evaluate 111In-labelled bleomycin complex (111In-BLMC) SPET in the differentiation of high- and low-grade gliomas. Nineteen glioma patients, 14 with high-grade and five with low-grade tumours, were studied 1, 4 and 24 h after the injection of 111In-BLMC. In the high-grade glioma group, there was significant uptake of 111In-BLMC in 12 patients and no uptake in two patients based on the visual classification of SPET images at 4 and 24 h. In the low-grade glioma group, one patient had low uptake at 4 and 24 h, but the other four patients showed no visible uptake. The mean tumour to extracerebral circulation activity ratio (T/Cr) at 4 h was 0.13 +/- 0.10 (n = 5) in low-grade gliomas and 1.7 +/- 1.0 (n = 14) in high-grade gliomas. At 24 h the T/Cr ratios were 0.56 +/- 0.21 and 3.4 +/- 1.7, respectively. The mean tumour to contralateral normal brain activity ratios (T/Br) were 5.0 +/- 3.9 (4 h) and 3.0 +/- 2.8 (24 h) in low-grade gliomas, and 37.2 +/- 37.3 (4 h) and 8.3 +/- 8.2 (24 h) in high-grade gliomas. These higher T/Br ratios did not, however, result in improved differentiation between the two groups of gliomas; at 4 h the T/Cr and T/Br ratios were of equal value, as two high-grade gliomas would have been misclassified as low-grade, but at 24 h the T/Br ratio resulted in more misclassifications. Our results show that 111In-BLMC can be used in the differentiation of high- and low-grade gliomas and that the selection of the reference area for calculating tumour to non-tumour ratios is important.

Radioimmunotherapy with 90Y-labeled monoclonal antibodies in a nude mouse ovarian cancer model

Tumor stroma contains much fibrin, and so monoclonal antifibrin antibody can accumulate in tumors. We treated nude mice bearing human ovarian carcinoma xenografts with 90Y-labeled monoclonal antifibrin antibody Fab fragments administered intratumorally. The survival time vs. a control group was significantly prolonged and tumor growth rate was decreased. Another group of animals was treated with 90Y-labeled OC 125-monoclonal antibody; these mice received the antibodies intratumorally, intraperitoneally or intravenously. The survival time was longest in the intratumorally treated group. There was no significant difference in survival between 90Y-labeled OC 125 and antifibrin in the intratumorally treated animal groups. The tissue activity distribution studies revealed that bone marrow is the critical organ. Intratumorally injected monoclonal 90Y-antifibrin antibodies were retained at least 36 h (up to 50% of injected activity per gram tumor tissue) in the xenograft after one treatment, causing cell death. Beta-camera imaging and immunohistochemistry were performed for studies of the correlation between 90Y activity and fibrin distribution in tumor specimens. These results were in concordance. In conclusion, intratumoral administration seems suitable for radioimmunotherapy, with an antibody that targets stromal structures. The accumulation can be successfully monitored by a beta-camera.

Plasma exchange therapy reduces the nursing care needed in Guillain-Barré syndrome

The authors compared the effect of plasma exchange therapy on the need for nursing care for 26 patients with acute idiopathic Guillain-Barré syndrome. The patients were randomized either to a plasma exchange (PE) or conservative treatment group. The need for nursing care and the need for specialist nursing services was assessed daily by the nurses at the Department of Neurology. At first, the average need for care was the same for the two groups of patients, but the pattern of care over time was different, with the PE group needing more care at the beginning and then very much less care, whilst the conservative group needed a more uniform amount of care over the entire stay at hospital. In the PE group the need for specialist nursing services increased markedly, and the need for nursing care decreased rapidly after the first 2 weeks to a level lower than that needed by control group patients, probably because PE increased muscle forces of patients. This study suggests that PE treatment is useful in reducing patients' needs for nursing care, especially after the first 2 weeks following the treatment.