Nanocellulose aerogels as 3D amyloid templates.

Proteins in solution tend to coat solid surfaces upon exposure. Depending on the nature of the surface, the environmental conditions, and the nature of the protein these adsorbed proteins may self-assemble into ordered, fibre-like structures called amyloids. Nanoparticulate surfaces, with their high surface to volume ratio, are particularly favourable to amyloid formation. Most prior research has focussed on either inorganic or organic nanoparticles in solution. In this research, we instead focus on aerogels created from TEMPO-oxidized cellulose nanofibers (TO-CNF) to serve as bio-based, three-dimensional amyloid templates with a tuneable surface chemistry. Previous research on the use of cellulose as a protein adsorption template has shown no evidence of a change in the secondary protein structure. Herein, however, with the aid of the reducing agent TCEP, we were able to induce the formation of amyloid-like 'worms' on the surface of TO-CNF aerogels. Furthermore, we demonstrate that the addition of the TO-CNF aerogel can also induce bulk aggregation under conditions where it previously did not exist. Finally, we show that the addition of the aerogel increases the rate of 'worm' formation in conditions where previous research has found a long lag-phase. Therefore, TO-CNF aerogels are shown to be excellent templates for inducing ordered protein aggregation.

2D foam film coating of antimicrobial lysozyme amyloid fibrils onto cellulose nanopapers.

Amyloid fibrils made from inexpensive hen egg white lysozyme (HEWL) are bio-based, bio-degradable and bio-compatible colloids with broad-spectrum antimicrobial activity, making them an attractive alternative to existing small-molecule antibiotics. Their surface activity leads to the formation of 2D foam films within a loop, similar to soap films when blowing bubbles. The stability of the foam was optimized by screening concentration and pH, which also revealed that the HEWL amyloid foams were actually stabilized by unconverted peptides unable to undergo amyloid self-assembly rather than the fibrils themselves. The 2D foam film was successfully deposited on different substrates to produce a homogenous coating layer with a thickness of roughly 30 nm. This was thick enough to shield the negative charge of dry cellulose nanopaper substrates, leading to a positively charged HEWL amyloid coating. The coating exhibited a broad-spectrum antimicrobial effect based on the interactions with the negatively charged cell walls and membranes of clinically relevant pathogens (Staphylococcus aureus, Escherichia coli and Candida albicans). The coating method presented here offers an alternative to existing techniques, such as dip and spray coating, in particular when optimized for continuous production. Based on the facile preparation and broad spectrum antimicrobial performance, we anticipate that these biohybrid materials could potentially be used in the biomedical sector as wound dressings.

Cocultivation of White-Rot Fungi and Microalgae in the Presence of Nanocellulose.

Cocultivation of fungi and algae can result in a mutualistic or antagonistic interaction depending on the species involved and the cultivation conditions. In this study, we investigated the growth behavior and enzymatic activity of two filamentous white-rot fungi (Trametes versicolor and Trametes pubescens) and two freshwater algae (Chlorella vulgaris and Scenedesmus vacuolatus) cocultured in the presence of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC). The growth of fungi and algae was studied in liquid, agar medium, and 3D-printed nanocellulose hydrogels. The results showed that cocultures grew faster under nutrient-rich conditions than in nutrient-depleted conditions. Key cellulose-degrading enzymes, including endoglucanase and laccase activities, were higher in liquid cocultures of T. versicolor and S. vacuolatus in the presence of cellulose compared to single cultures of fungi or algae. Although similar results were observed for cocultures of T. pubescens and C. vulgaris, laccase production diminished over time in these cultures. Fungi and algae were capable of growth in 3D-printed cellulose hydrogels. These results showed that cellulase enzyme production could be enhanced by cocultivating white-rot fungi with freshwater algae under nutrient-rich conditions with TEMPO-CNF and CNC. Additionally, the growth of white-rot fungi and freshwater algae in printed cellulose hydrogels demonstrates the potential use of fungi and algae in hydrogel systems for biotechnological applications, including biofuel production and bio-based fuel cell components. IMPORTANCE Depending on the conditions used to grow fungi and algae in the lab, they can interact in a mutually beneficial or negative way. These interactions could stimulate the organisms to produce enzymes in response to the interaction. We studied how wood decay fungi and freshwater algae grew in the presence and absence of cellulose, one of the basic building blocks of wood. How fungi and algae grew in 3D-printed cellulose hydrogels was also tested. Our results showed that fungi and algae partners produced significantly larger amounts of enzymes that degraded cellulose when grown with cellulose than when grown alone. In addition, fungi and algae were shown to grow in dense nanocellulose hydrogels and could survive the shear conditions during gel structuring while 3D-printing. These cultures could potentially be applied in the biotech industry for applications like energy production from cellulose, biofuel production, and bioremediation of cellulose material.

Assessment of S values for I131 and Y90 based on the Digimouse voxel phantom.

INTRODUCTION: Most preclinical studies using radiopharmaceuticals have been carried out on mice. In nuclear medicine and radioimmunotherapy procedures, I131 and Y90 have been widely used. For better estimation of doses from these procedures, S value plays a vital role. In this study, we have evaluated S values for major source and target combinations of Digimouse voxel phantom. MATERIALS AND METHODS: We have used the Digimouse voxel phantom which was incorporated in Monte Carlo code FLUKA. Simulation studies were performed using Monte Carlo simulation code FLUKA. Latest publication of International Commission on Radiological Protection (ICRP) report 110 was used for assigning the values of organ compositions and densities. Photon and electron spectra for I131 and Y90 have been taken from the ICRP publication 107. For Digimouse voxel phantom, we have simulated 9 source regions with an assumed uniform distribution of I131 and Y90. RESULTS AND DISCUSSION: S values have been evaluated for I131 and Y90 for different source and target combinations of Digimouse voxel phantom and presented in tabular form. The S values can be applied prospectively or retrospectively to the calculation of radiation doses internally exposed to I131 and Y90, including nuclear medicine and radioimmunotherapy procedures. These S values have been very important for the calculation of absorbed doses for various organs similar in size to present study for mice. CONCLUSION: In this study S value for I131 and Y90 were evaluated for major organs of digimouse voxel phantom. These S values are very important for absorbed dose calculation for various organs of a mouse.

Underdosing of the maxillary sinus for small fields used in newer radiotherapy techniques: Comparison of thermoluminescent dosimeter and Monte Carlo data.

AIMS: To evaluate the underdosing of the maxillary sinus at its distal end produced by air cavity in the path of the 6 MV photon beam. MATERIALS AND METHODS: A cubic solid water slab phantom of dimensions 18 cm × 18 cm × 18 cm with 4 cm × 4 cm × 4 cm air cavity 3 cm away from its anterior surface was used in this study. The percentage depth dose (PDD) for 6 MV X-rays along the central axis of the cubical air cavity was measured using thermoluminescent dosimeter-100 chips. The EGSnrc/DOSXYZnrc Monte Carlo (MC) code was used to estimate the PDD values in both homogeneous and inhomogeneous conditions. The dose data were generated for 1 cm × 1 cm, 2 cm × 2 cm, 3 cm × 3 cm, and 5 cm × 5 cm field sizes. RESULTS: Average percentage dose reductions at 1 mm beyond the distal surface of the maxillary sinus for the field sizes 1 × 1, 2 × 2, and 3 × 3 cm2 are 42.4%, 39.5%, and 29.4%, respectively. However, for 5 cm × 5 cm field size, there is a dose enhancement (i.e., overdosing) at 1 mm from the distal surface of the maxillary sinus and the average percentage dose enhancement is 5.9%. Also, beyond 1 cm from the air-water interface, there is dose enhancement for all the field sizes. CONCLUSION: This study showed that the significant dose reduction occurs near the air-water interface for the treatment techniques using small photon fields such as intensity-modulated radiotherapy or other newer techniques. MC-based treatment planning calculation predicts realistic dose distribution while using small photon fields in the treatment of maxillary sinus.

A clinico-epidemiological study of cognitive function status of community-dwelling elderly.

BACKGROUND: Cognitive decline and dementia are an important problem affecting quality-of-life in elderly and their caregivers. There is regional variation in prevalence of cognitive decline as well as risk factors from region to region. AIM: The aim was to determine the prevalence of dementia and cognitive decline and its various risk factors in the elderly population of more than 60 years in Eastern Uttar Pradesh (India). MATERIALS AND METHODS: A camp-based study was conducted on rural population of Chiraigaon block of Varanasi district from February 2007 to May 2007. Block has 80 villages, of which 11 villages were randomly selected. Eleven camps were organized for elderly people in 11 randomly selected villages on predetermined dates. A total of 728 elderly persons of age >60 years were examined, interviewed and data thus collected was analyzed. Elderly who got Hindi-mini-mental state examination (HMSE) score developed by Ganguli based on the Indo-US Cross-National Dementia Epidemiology Study) score ≤23 were evaluated further and in those with confirmed cognitive and functional impairment, diagnosis of dementia was assigned according to Diagnostic and Statistical Manual for Mental Disorder fourth edition criteria after ruling out any psychiatric illness or delirium. Based on International Classification of Diseases-10 diagnostic criteria sub-categorization of dementia was done. RESULTS: Mean, median and 10(th) percentile of HMSE of the study population were 23.4, 24 and 17, respectively. About 14.6% elderly had scored <17. 42.9% of rural elderly population had HMSE score <23, 70.6% <27 and 27.7% between 23 and 27. Literate people had statistically significant higher mean HMSE score (26.1 ± 3.9) than illiterate people (22.9 ± 4.9). Other risk factors were female gender, malnutrition, and obesity. Prevalence of dementia was 2.74%; in male 2.70% and in female 2.80%. Most common type of dementia was Alzheimer (male 1.5%, female 1.5%) followed by vascular (male 1.2%, female 0.6%) and others 0.6% (male 0%, female 0.6%). CONCLUSIONS: Study showed that a very high percentage of rural elderly attending health camps had poor cognitive function score; though the prevalence of dementia was relatively low. Alzheimer dementia was most common, followed by vascular dementia, which was predominant in males. Illiteracy, age, and under-nutrition were the most important risk factors for poor cognitive function. Our study suggest that cut-off of HMSE score should be 17 (10(th) percentile) for illiterate population.

Fetal warfarin syndrome.

A case of a baby born preterm with an antenatal diagnosis of aortic coarctation for which prostin was electively started at birth. The baby was found to be profoundly anaemic with no clear obstetric cause. Features consistent with antenatal intracerebral haemorrhage were noted on cranial ultrasonography in the context of severe coagulopathy, prompting investigations which confirmed fetal-maternal haemorrhage. It transpired that, following aortic and mitral valve replacements, the mother was anticoagulated with warfarin at conception, having misunderstood her cardiologist's advice that: 'you cannot get pregnant whilst on warfarin'. Following conversion to low molecular weight heparin, she suffered a stroke, thus warfarin was restarted, with an international normalised ratio of 3-4.7 during pregnancy. Following transfer to the paediatric intensive care unit, fetal warfarin syndrome was diagnosed. The coagulopathy and anaemia were corrected and aortic coarctation was excluded. The baby returned to the neonatal intensive care unit for ongoing care and was discharged home in good condition around his due date. At the present time, there is no clinically overt neurological deficit.