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We attempted to produce three dimensional (3D) aero-sponges using liquid silk (LS) extracted from the silk glands of fully grown larvae of Bombyx mori silkworms by combining an ice-crystal-sublimat...

We attempted to produce three dimensional (3D) aero-sponges using liquid silk (LS) extracted from the silk glands of fully grown larvae of Bombyx mori silkworms by combining an ice-crystal-sublimation method and a water-annealing treatment. The pore structure of the 3D LS-aero-sponge was constructed by the branched fibrous substrates and the films with small holes. It was assumed that the branched fibrous structure was mainly comprised of fibroin whereas the films were comprised of the fibroin interacting with the sericin fractions. Most of the WAXD peaks from the as-molded 3D LS-aerosponge could be assigned to the silk1 crystal diffraction peaks of fibroin. The silk1 crystal modification of fibroin formed in the course of the production of the 3D LS-aero-sponge could bring about a good thermal shrinkproof property. Furthermore, a gamma ray irradiation treatment applied prior to the cell proliferation tests of the 3D LS-aero-sponges was found to be effective to form cross-linking in the sericin fractions. As a result, the yield stress in the compression tests of the 3D LS-aero-sponges was increased. The 3D LS-aerosponge exhibited a good living cell proliferation properly in the culture tests using NH3T3 cells (Swiss albino mice embryonic fibroblasts) although that of the 2D LS-cast films was very poor. We suggest the good cell proliferation property of the 3D LS-aerosponge was due to the continuous branched fibrous structure comprised of fibroin.

Islet transplantation is a promising option for the clinical treatment of insulin-dependent diabetes, but a reliable islet cryopreservation/transplantation protocol should be established to overcome the donor shortage. The current study reports that a silk fibroin (SF) sponge disk can be used as a cryodevice for vitrification of large quantity pancreatic islets and the scaffold for subsequent subrenal transplantation in a rat model. The marginal islet mass (550 islet equivalents [IEQs]) on an SF sponge disk was vitrified-warmed and transplanted beneath the kidney capsule of a streptozotocin-induced diabetic rat with or without vascular endothelial growth factor (VEGF). Subrenal transplantation (no scaffold) of 550 IEQ fresh islets and post-warm islets vitrified on a nylon mesh device resulted in achieving euglycemia of recipient rats at 60% and 0%, respectively. Transplantation of 550 IEQ islets vitrified-warmed on an SF sponge disk failed to achieve euglycemia of recipient rats (0%), but the VEGF inclusion in the SF sponge disk contributed to acquiring the euglycemic recipients (33%). All cured recipient rats regained hyperglycemia after nephrectomy, and the histopathologic analysis exhibited a well-developing blood vessel network into the islet engrafts. Thus, an SF sponge disc was successively available as the cryodevice for islet vitrification, the transporter of the angiogenic VEGF, and the scaffold for subrenal transplantation in the rat model.

This work established an energy-saving and straightforward treatment of cellulosic pulp to obtain functional cellulose nanofibers equipping them at the same time with catalytic activity and flame-r...

Minimum volume cooling (MVC) procedure has been successfully applied to vitrify mammalian oocytes, but high skill of capillary pipetting is required to load the oocytes on a cryodevice with a minimal volume (1 μL) of vitrification solution (VS). Here we report a novel cryodevice for bovine oocyte vitrification, silk fibroin (SF) sheet multilayer, of which spontaneous absorption property can eliminate pipette operation for removal of excess VS. Based on physical stability and scanning electron microscopic observation, the SF sheet prepared from 1.5% (wt/vol) fibroin solution was selected and layered around a polypropylene strip (0.1-mm thickness, 0.7-mm width, 10-mm depth). Ten denuded bovine mature oocytes were loaded onto the SF sheet multilayer with 2-3 μL of the VS, and then cooled rapidly by plunging into liquid nitrogen. Nylon mesh (NM) device with square opening 37-μm length of a side and commercially available Cryotop® (CT) device were used as controls, and the minimization of VS volume was performed by paper towel absorption and capillary aspiration, respectively. In SF, NM and CT groups, post-warming oocyte recovery rates were 99.5, 99.1 and 100%, and the morphological survival rates were 99.7, 94.5 and 99.0%, respectively. Subsequent IVF and 8-days IVC resulted in comparable blastocyst yields among the three groups (25.5, 25.0 and 26.1% in SF, NM and CT groups, respectively). These results suggest that SF sheet multilayer is a useful cryodevice for bovine matured oocytes in MVC vitrification because VS volume surrounding the oocytes can be easily minimized through its absorption property.

Decreased swallowing function increases the risk of choking and aspiration pneumonia. Videofluoroscopy and computed tomography allow for detailed observation of the swallowing movements but have radiation risks. Therefore, we developed a method using surface electromyography (sEMG) to noninvasively assess swallowing function without radiation exposure. A 44-channel flexible sEMG sensor was used to measure the sEMG signals of the hyoid muscles during swallowing in 14 healthy young adult and 14 elderly subjects. Muscle synergy analysis was performed to extract the muscle synergies from the sEMG signals, and the three synergies were extracted from the hyoid muscle activities during the swallowing experiments. The experimental results showed that the three synergies represent the oral, early pharyngeal, and late pharyngeal swallowing phases and that swallowing strength is tuned by the strength of the muscle activities, whereas swallowing volume is controlled by adjusting muscle activation timing. In addition, the timing of the swallowing reflex is slower in elderly individuals. The results confirm that the proposed approach successfully quantifies swallowing function from sEMG signals, mapping the signals to the swallowing phases.

A simple method by which the functional peptide of Gly-Arg-Gly-Asp-Ser (GRGDS) is immobilized on the surface of silk fibroin (SF) films via Gly-Ala-Gly-Ala-Gly-Ser (GAGAGS) sequences is proposed. GAGAGS, a repeating amino acid sequence in the crystal region of Bombyx mori SF, performs a key role in interacting with and immobilizing SF molecules. Immobilization by this proposed method involves no chemical reaction, thereby preserving the original properties of the SF molecule. The density of GRGDS peptides existing on SF film was found to be higher in the GAGAGS-bound type than in the non-GAGAGS-bound type. Furthermore, results showed that the amount of immobilized (GAGAGS)GRGDS peptide increased as the β-sheet crystallization was promoted in the SF film. Fibroblasts, which adhered to the surface of the SF film, showed more extensibility because of the (GAGAGS)GRGDS immobilization, which suggests that the cell adhesion activity of RGD is functioning effectively.

The molecular weight (MW) of regenerated silk fibroin (RSF) decreases during degumming and dissolving processes. Although MW and the MW distribution generally affect polymer material processability and properties, few reports have described studies examining the influences of MW and the distribution on silk fibroin (SF) material. To prepare different MW SF fractions, the appropriate conditions for fractionation of RSF by ammonium sulfate (AS) precipitation process were investigated. The MW and the distribution of each fraction were found using gel permeation chromatography (GPC) and SDS-polyacrylamide electrophoresis (SDS-PAGE). After films of the fractionated SFs formed, the secondary structure, surface properties, and cell proliferation of films were evaluated. Nanofiber nonwoven mats and 3D porous sponges were fabricated using the fractionated SF aqueous solution. Then, their structures and mechanical properties were analyzed. The results showed AS precipitation using a dialysis membrane at low temperature to be a suitable fractionation method for RSF. Moreover, MW affects the nanofiber and sponge morphology and mechanical properties, although no influence of MW was observed on the secondary structure or crystallinity of the fabricated materials.

We investigate the mechanical properties and structure of silk resins as potential alternatives to tortoiseshell for producing eyeglass frames and various ornaments. Silk powders are obtained from Bombyx mori and Eri silk waste fibers before the degumming process. The powders are fabricated into resins via simple hot pressing under a pressure of 31.2 MPa at temperatures in the range 150–180 °C. The results indicate that the B. mori resins have higher micro-Vickers hardness, three-point bending strength, and elastic modulus (66 Hv, 122 MPa, and 8.7 GPa, respectively) compared to the Eri silk resins (58 Hv, 95 MPa, and 8.2 GPa, respectively). The better mechanical properties of the fibroin resins are related directly to longer drying times. The optimum drying conditions are found to be at a temperature of 100 °C under a–vacuum of −0.1 MPa for a time of 7 d. ATR-FTIR and XRD results show how the fibroin structure changes after resinification and drying. The morphology and the distribution size of particle of the silk powders and the fractured surfaces of the resins are analyzed from SEM micrographs. The present findings demonstrate that silk resins are suitable materials for developing useful applications because of their favorable mechanical properties.

Introduction: Jaw-opening force (JOF) can be a potential screening tool for dysphagia. However, confounding variables such as comorbidities or physical and oral functions that are associated with the physiology of swallowing have not previously been examined. Adjusting for these variables could reveal the relationship between JOF and dysphagia and indicate whether JOF is an independent factor associated with dysphagia. We therefore aimed to assess the efficacy of using JOF for dysphagia screening in this multi-institutional study. Methods: Community-dwelling older adults over the age of 65 years (N = 403) who visited the university dental hospitals and participated in health surveys (mean age ± standard deviation, 77.1 ± 7.0 years; range, 65–96 years) between November 2018 and January 2020 were included in this study. The JOFs of all participants were measured. The measured JOF was compared with the presence of dysphagia, which was defined using the Functional Oral Intake Scale and the Eating Assessment Tool-10. Results: Multiple logistic regression analysis revealed that the presence of dysphagia was independently associated with JOF, calf circumference, and dependence after adjusting for age and sex. Discussion/Conclusion: Decreased JOF can be a risk factor for dysphagia in older adults.

Recently, bio-based electrospun nanofiber mats (ENMs) have gained substantial attention for preparing polymer-based biomaterials intended for use in cell culture. Herein, we prepared poly(ethylene-glycol 1,4-Cyclohexane dimethylene-isosorbide-terephthalate) (PEICT) ENMs using the electrospinning technique. Cell adhesion and cell viability of PEICT ENMs were checked by fibroblast cell culture. Field emission electron microscope (FE-SEM) image showed a randomly interconnected fiber network, smooth morphology, and cell adhesion on PEICT ENM. Fibroblasts were cultured in an adopted cell culturing environment on the surface of PEICT ENMs to confirm their biocompatibility and cell viability. Additionally, the chemical structure of PEICT ENM was checked under Fourier-transform infrared (FTIR) spectroscopy and the results were supported by -ray photoelectron (XPS) spectroscopy. The water contact angle (WCA) test showed the hydrophobic behavior of PEICT ENMs in parallel to good fibroblast cell adhesion. Hence, the results confirmed that PEICT ENMs can be potentially utilized as a biomaterial.

We report the adaptability of rat islets vitrified-warmed on nylon mesh (NM) device or silk fibroin (SF) sponge disc for the normalization of the blood glucose level in rat models of diabetes. One-hundred rat islets were cryopreserved according to a minimum volume cooling protocol on an NM device or a solid surface vitrification protocol on an SF sponge disc. The recovery rate (97.1% vs. 93.8%), the viability (77.9% vs. 74.4%), and the stimulation index (4.7 vs. 4.2) in glucose-stimulated insulin secretion (GSIS) assay of the post-warm islets were comparable between the NM vitrification and the SF vitrification groups. The viability and the stimulation index of the fresh control islets were identified to be 97.5% and 6.5, respectively. Eight hundred islets from the NM or the SF vitrification group or the fresh control group were transplanted beneath the kidney capsule of a streptozotocin-induced diabetic rat (blood glucose level > 350 mg/dl). Within 3 weeks after transplantation, the acquisition of euglycemia (< 200 mg/dl) was observed in recipient rats (80.0–83.3%). An intraperitoneal glucose tolerance test on Day-30 and Day-60 showed similar 2-h responses to the glucose uptake of cured rats among the compared groups. Moreover, the successful engraftment of transplants was confirmed by the Day-70 nephrectomy through the subsequent diabetes reversal and histological evaluation. Thus, large quantities of rat islets vitrified-warmed on an NM device or an SF sponge disc were proven to be fully functional both in vitro and in vivo, due to the GSIS and syngeneic transplantation, respectively.

Silk fibroin produced by the domesticated silkworm, Bombyx mori, has been studied widely as a substrate for tissue engineering applications because of its mechanical robustness and biocompatibility. However, it is often difficult to precisely tune silk fibroin’s biological properties due to the lack of easy, reliable, and versatile methodologies for decorating it with functional molecules such as those of drugs, polymers, peptides, and enzymes necessary for specific applications. In this study we applied an azido-functionalized silk fibroin, AzidoSilk, produced by a state-of-the-art biotechnology, genetic code expansion, to produce silk fibroin decorated with cell-repellent polyethylene glycol (PEG) chains for controlling the cell adhesion property of silk fibroin film. Azido groups can act as selective handles for chemical reactions such as a strain-promoted azido-alkyne cycloaddition (SPAAC), known as a click chemistry reaction. We found that azido groups in AzidoSilk film were selectively decorated with PEG chains using SPAAC. The PEG-decorated film demonstrated decreased cell adhesion depending on the lengths of the PEG chains. Azido groups in AzidoSilk can be decomposed by UV irradiation. By partially decomposing azido groups in AzidoSilk film in a spatially controlled manner using photomasks, cells could be spatially arranged on the film. These results indicated that SPAAC could be an easy, reliable, and versatile methodology to produce silk fibroin substrates having adequate biological properties.

A Forster/fluorescence resonance energy transfer (FRET)-based molecular tension sensor was originally reported by the fusion of intracellular molecules, which has contributed to the elucidation of cell mechanotransduction. However, it is still unclear whether recombinant tension sensors can detect forces in the extracellular environment. Here, we developed a recombinant FRET-based tension sensor (rFRET-TS) and immobilized it to a glass surface. Fibroblasts seeded onto the surface likely bound to an RGDS peptide fused to one terminal of the rFRET-TS, and intra-molecular FRET was dominantly observed on the sensor-immobilized surface compared to inter-molecular FRET. Time-lapse FRET imaging showed that the rFRET-TS enabled the real-time visualization of forces between cells and material surfaces that stemmed from focal adhesion formation and actin cytoskeletal reorganization. This sensor is expected to be useful for clarifying cell–scaffold mechanical interactions by its insertion between protein molecules of the scaffold, which will provide clues for the control of cell behavior in/on scaffolds.

Silk fibroin (SF), which offers the benefits of biosafety, biocompatibility, and mechanical strength, has potential for use as a good biomedical material, especially in the tissue engineering field. This study investigated the use of SF biomaterials as a wound dressing compared to commercially available collagen materials. After human fibroblasts (WI-38) were cultured on both films and sponges, their cell motilities and gene expressions related to wound repair and tissue reconstruction were evaluated. Compared to the collagen film (Col film), the SF film induced higher cell motility, higher expressions of genes were observed on the SF film. Extracellular matrix production-related genes were up-regulated in WI-38 fibroblasts cultured on the SF sponges. These results suggest that SF-based biomaterials can accelerate wound healing and tissue reconstruction. They can be useful biomaterials for functional wound dressings.

Scientific efforts have been made to study and develop the efficient product to be used beyond conventional antibiotic treatments against bacteria and funguses mainly in the wound dressing. Therefore, in this innovative study, the authors investigated the development of hybrid nanofibers of chitosan/polyvinyl alcohol/nano-hydroxyapatite with the composition of copper nanoparticles for wound dressing potential. Therefore, copper/silver with ratio 1:1, copper nanoparticles and silver nanoparticles were chosen as variable to comparison the biocompatibility and antibacterial properties between copper and silver nanoparticles. The nanoparticle loaded to nanofibers by the in-situ method to prepare the chemical bonding between nanofibers and nanoparticles. All characterization results were appreciable for successful synthesis of nano-hydroxyapatite in the nanofibers matrix and loading metallic nanoparticles with chemical reactions between nanoparticles and nanofibers, due to OH deformation of Cs/PVA/nHA nanofibers and reaction with nano-particles. Although the in-vitro results showed PVA/Cs nanofibers loaded with Cu/Ag nanoparticles, is the most appropriate sample for wound dressings because it has very good inhibition zone against the gram negative and gram positive bacteria. This composite also has the good biocompatibility and no toxicity which is good sign for cell attachment and biocompatibility.

Electrospinning was used to fabricate the different ratio of poly [(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBH)/Poly (vinyl alcohol) (PVA) blend nanofibers. These nanofibers of ratio PHBH/PVA 100/0, 90/10, 70/30, and 50/50 were prepared by using HFIP as solvent. Mixed solvent of HFIP/water was used to prepare for PHBH/PVA 30/70, 10/90 and water was used for pure PVA. The characteristic of morphology, thermal properties, miscibility, wettability, water absorption, and enzymatic biodegradable behaviour of these blend nanofibers have been investigated. The result indicated that PHBH/PVA blend nanofibers are immiscibility in the crystalline phase from DSC analysis with two peaks appear in 137 °C and 230 °C in the blend nanofibers. WAXD pattern of the blend nanofiber also exhibited the decrease of PHBH crystalline intensity with the increase of PVA content. However, FTIR spectra of blend nanofiber displayed the shift of hydroxyl and carbonyl stretching band which indicates the intermolecular interaction in amorphous phase. The water contact angle values increased with the increase of PVA content more than 30%. These showed the surface of blend nanofibers were hydrophobic since WCA value was more than 90°. The increase of WCA value is due to surface morphological change that is the decrease of fiber diameter. Nevertheless, blend nanofibers of PHBH/PVA of 70/30 exhibited the high water absorption more than 350% from initial weight. SEM-photograph of samples after immersing in the water showed that structure of nanofiber did not change in blend ratio of more over 50% PHBH content. These nanofibers of pure PHBH and ratio PHBH/PVA of 90/10, 70/30, and 50/50 will expect to be useful material to have the biocompatibility with cell attachment. In vitro enzymatic biodegradable resulted that degradation rate of blend nanofiber can be greatly improved by ratio of PVA polymer. NIH3T3 cells attached and proliferated well on pure PHBH nanofiber. However, blend nanofibers with PVA-rich content inhibited growth of the NIH3T3 cells.

The objective of this study is to compare the spinnability, morphology, structure, mechanical properties, and cell compatibility of the silk fibroin nanofiber nonwoven electrospun fabrics using aqu...

Objective self-assessment is essential to learning and continued competence in dentistry. A computer-assisted design/computer-assisted manufacturing (CAD/CAM) learning software (prepCheck, Sirona) allows students to objectively assess their performance in preclinical prosthodontics. The aim of this study was to evaluate students' perceptions of CAD/CAM learning software for preclinical prosthodontics exercises. In 2014, all third-year dental students at Harvard School of Dental Medicine (n=36) were individually instructed by a trained faculty member in using prepCheck. Each student completed a preclinical formative exercise (#18) and summative examination (#30) for ceramometal crown preparation and evaluated the preparation using five assessment tools (reduction, margin width, surface finish, taper, and undercut) in prepCheck. The students then rated each of the five tools for usefulness, user-friendliness, and frequency of use on a scale from 1=lowest to 5=highest. Faculty members graded the tooth preparations as pass (P), marginal-pass (MP), or fail (F). The survey response rate was 100%. The tools for undercut and taper had the highest scores for usefulness, user-friendliness, and frequency of use. The reduction tool score was significantly lower in all categories (p

Non-woven mats of Bombyx mori silk fibroin were fabricated using electrospinning with an all aqueous solution at

Wound dressings are the primary barrier between the wound surface and the outer environment. Here we report the fabrication of cellulose acetate (CA)–Manuka honey (MH) composite nanofibrous mats as a biocompatible and antimicrobial wound dressing. CA mats with different quantities of MH were developed by electrospinning. The ATR-FTIR spectra confirm the inclusion of MH in the composite CA-MH nanofibrous mats. The fibers were continuous and bead-free with acceptable mechanical properties. The fiber diameter increased with an increase in MH content. Inclusion of MH in the electrospun composite CA-MH nanofibrous mats shows high efficacy to prevent bacterial growth on the wound surface. The MH loaded CA nanofiber mats showed good antioxidant abilities, while the ability to free radicalize the DPPH was dependent upon the factors of MH content in the fiber and the time of immersion in the DPPH solution. Besides, the nanofibrous mat's high porosity (85–90%) and WVTR values of 2600 to 1950 g/m2/day, suitable for wound breathability and the mats show high cytocompatibility to NIH 3T3 cell line in in vitro testing, proving to be effective for promoting wound healing.

Adequate oral status and functional assessments are important for dysphagia rehabilitation in acute care inpatient settings, especially to establish individualised oral intake. However, the association between food intake levels and oral function has not been elucidated in acute care inpatients. This cross-sectional study clarified the association between oral intake levels and the oral status/function of patients with dysphagia admitted to acute care settings. Admitted patients aged ≥40 years (n = 459; men: 288; mean age: 70.8 ± 12.0) examined at the Department of Dysphagia Rehabilitation at the Iwate Medical University Hospital from April 2007 to March 2014 were included. The oral health status was evaluated by the tongue coating, oral dryness severity, plaque control, posterior occlusal support and a repetitive saliva swallowing test (RSST). Dysphagia severity was determined from the Dysphagia Severity Scale. Oral intake levels were evaluated using the Functional Oral Intake Scale (FOIS) at the time of the initial dental examination (FOIS-I), and they were re-evaluated after the revision of levels according to the participants' general condition and oral health status (FOIS-R). Divergence between FOIS-I and FOIS-R was noted in >40% patients. Multiple regression analysis showed significant associations between FOIS-R and consciousness level, activities of daily living, tongue coating, RSST and posterior occlusal support. Patients with dysphagia in acute care settings require detailed assessments of their oral status and function, including swallowing, to determine the most suitable feeding methods and dental interventions to improve oral intake levels.

The chemical resemblance of HA to natural bone has led to a widespread research approach to use synthetic HA as a bone substitute and replacement in biomedical application. Nanofibrous composites comprised of bioactive HA has been considered as a promising material for bone regeneration. However, the inadequate mechanical performance by HA agglomeration on nanofiber polymer matrix during electrospinning is a demanding challenge. In this study, we fabricated composite nanofibrous scaffold from the blends of PAN, nCB, and HA via electrospinning to observe the effect of nCB on the membrane properties. All the prepared samples were characterized by SEM-EDX, TEM, FTIR, XRD, TGA, water contact angle, swelling, and tensile strength test. Mineralized samples were also characterized by SEM-EDX, FTIR, XRD, and XPS. Incorporation of nCB reduced the average diameter of nanofibers without any significant changes in surface morphology in PAN/nCB scaffold. EDX spectra demonstrated an incremental increase in HA components with an increase in the amount of HA loading. TEM micrographs revealed dispersed nCB on the nanofibrous structure. Significant improvement in mechanical performance was observed in PAN/nCB/HA compared to PAN/HA scaffolds. Although an increase in the amount of HA in PAN/nCB/HA caused a reduction in the tensile strength and Young's modulus, the values were still greater than those without nCB. PAN/nCB/HA composite scaffold showed excellent mineralization of HA (Ca/P = 1.68) with platelet-like clustered protrusions (typical HA morphology) after incubation in SBF. MC3T3-E1 osteoblast cells showed excellent proliferation and adhesion on our prepared membranes. Our findings have demonstrated that nCB can strengthen the HA-based polymeric nanofibers and such biocompatible composites have strong potential to be used as bone and other hard tissue restoring materials.

Large osteochondral defects have been difficult to repair via tissue engineering treatments due to the lack of a sufficient number of source cells for repairing the defect and to the severe mechanical stresses affecting the replacement tissue. In the present study, whole-area osteochondral defects of rabbit patella were covered and wrapped with a fibroin sponge containing chondrocytes, with or without Green Fluorescent Protein (GFP) transgenic marking, on the surface facing the osteochondral defect. Five of eight osteochondral defects that were covered with the chondrocyte-seeded fibroin sponges showed hyaline cartilage-like repair containing no fibroin fragments at 6 weeks after surgery. The repaired tissue showed a layer formation, which showed intensive safranin-O and toluidine blue staining, and which showed positive type II collagen immunostaining. The average surface coverage of the repaired cartilage was 53%. On average, 48% of the cells in the repaired tissue were derived from GFP transgenic chondrocytes, which had been seeded in the fibroin sponge. The fibroin-sponge covering had the potential to allow the early repair of large osteochondral defects. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1474-1482, 2016.

Background Recently, silk fibroin-based biomaterials have received attention for application in tissue engineering and drug delivery systems. The usefulness of heat sterilization methods for silk fibroin-based biomaterials was investigated in this study as all biomaterials are required to undergo a sterilization process when they are used in medical devices. Methods The influence of wet and dry heating on the properties of fibroin molecules in silk fibroin sponges was investigated by measurements of solid-state 13C cross-polarization/magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analyses, strength tests, and cell proliferation/migration assays. Results 13C CP/MAS NMR spectra of wet-heated sponges revealed no changes in the molecular structure below 50 °C. However, above 60 °C, the crystalline structure of the silk proteins transitioned from silk I to silk II; the silk II:silk I ratio increased with temperature. In contrast, dry heating (below 190 °C for up to 180 min) induced no structural changes in the fibroin molecules. These results indicate that, although autoclave sterilization (121 °C for 20 min) induces structural changes in silk fibroin sponges, no such changes are observed with the dry-heat sterilization (180 °C for 30 min). Sterilized sponges with a silk I structure can be obtained using dry-heat method during sterilization. Moreover, the structural differences between the wet- and dry-heated silk fibroin sponges did not influence their interaction with fibroblasts. Discussion This study indicates that both autoclaving and dry heating are acceptable sterilization methods for silk fibroin-based sponges as the scaffold. In particular, dry heating maintains the stability of the secondary structure of the sterilized silk fibroin-based biomaterials.

BACKGROUND There are some clinical reports on dysphagia in patients with chronic obstructive pulmonary disease (COPD); however, its pathophysiology remains largely unknown.Changes in respiratory function occur in patients with COPD causing a decrease in tidal volume and an increase in respiratory rate (tachypnea). In addition, it leads to lack of coordination between respiration and swallowing.A new treatment called nasal high flow (NHF) has been introduced for patients with COPD, replacing the traditional non-invasive ventilation (NIV) procedure. The NHF therapy involves inhalation of high flow of humidified air, which reduces respiratory effort in patients with COPD. Furthermore, NHF therapy facilitates swallowing of saliva even during respiratory management. A recent clinical study reported that high-flow nasal cannula oxygen therapy for 6 weeks improved the health-related quality of life and reduced hypercapnia in patients with stable COPD. Taken together, NHF therapy is gaining attention in the clinical management of patients with COPD.Therefore, in this study, we aim to examine the efficacy of NHF therapy on the coordination between breathing and swallowing of saliva during daytime nap in patients with COPD. METHODS/DESIGN This open-label, investigator-initiated, single center study will evaluate the efficacy of NHF therapy on the coordination between breathing and swallowing of saliva during the daytime nap in COPD patients with forced expiratory volume in 1 second (FEV1%) of

In this study, the physical properties and the biocompatibility of electrospun silicone-modified polyurethane (PUSX) nanofibers were discussed and compared with PUSX films. To investigate the effects of different structures on the physical properties, tensile strength, elongation at break, Young&rsquo, s modulus, water retention, water contact angle (WCA) and thermal conductivity measurements were performed. To prove the in vitro biocompatibility of the materials, cell adhesion, cell proliferation, and cytotoxicity were studied by NIH3T3 mouse embryonic fibroblasts cells following by lactate dehydrogenase (LDH) analysis. As a conclusion, the mechanical properties, water retention, and WCA were proven to be able to be controlled and improved by adjusting the structure of PUSX. A higher hydrophobicity and lower thermal conductivity were found in PUSX nanofibers compared with polyurethane (PU) nanofibers and films. An in vitro biocompatibility evaluation shows that the cell proliferation can be performed on both PUSX nanofibers and films. However, within a short period, cells prefer to attach and entangle on PUSX nanofibers rather than PUSX films. PUSX nanofibers were proven to be a nontoxic alternative for PU nano-membranes or films in the biomedical field, because of the controllable physical properties and the biocompatibility.

To evaluate silk fibroin sponge (SFS) materials as dressings for wound repair in comparison with collagen material, human epidermal keratinocytes (HEKs) were cultured on silk fibroin materials in the absence of differentiation factors. Higher cell motility, which is known to play an important role during wound repair, was observed on silk fibroin than on collagens. More HEKs on the silk fibroin surface were flatter and elongated, indicating a higher migration stage of HEKs than that shown on the other surface. Quantitative RT-PCR results revealed up-regulated gene expression of HEKs to the differentiation stage related to skin reconstruction. We observed higher gene expression profiles of keratinocyte-specific differentiation markers in HEKs cultured on silk fibroin surfaces than those observed on collagen surfaces. Higher gene expression related with wound healing such as granulin (GLN), which is reported as an important growth factor for wound repair, was found by DNA microarray analysis in HEKs cultured on SFS than oncollagen sponge. Scar-formation-related genes at the wound site were expressed in HEKs on SFS less than on collagen sponge. These gene expression results suggest that silk fibroin-based biomaterials used as a wound dressing can hasten skin reconstruction (epithelialization) and wound repair with formation of less scar tissue during wound healing.

This study was designed to investigate whether cryosurvival of rat pancreatic islets can be improved by carboxylated e-poly- l -lysine (CPLL). Islets isolated from Wistar × Brown-Norway F1 rats (101–200 μm in diameter) were cryopreserved in three vitrification solutions containing ethylene glycol (EG; 30%, v/v) and CPLL (0%, 10%, or 20%, v/v) by Cryotop® protocol (10 islets per device). The post-warm survival rate of the islets vitrified in the presence of 20% CPLL (74%), assessed by FDA/PI double staining, was higher than those in 0% and 10% CPLL (65% and 66%, respectively). Decreased EG concentrations (10% and 20%) in the presence of 20% CPLL resulted in impaired post-warm islet survival rates (50% and 64%, respectively). Value of stimulus index (SI) for 20 mM/3 mM glucose-stimulated insulin secretion was 4.1 in islets vitrified-warmed in the presence of 30% EG and 20% CPLL, which was comparable with those in fresh control islets and vitrified islets in 30% EG alone (4.1 and 4.4, respectively). A large number of islets (50 islets per device) could be cryopreserved in the presence of 30% EG and 20% CPLL by using nylon mesh as the device, without considerable loss of post-warm survival (68%) and SI value (3.7). In conclusion, supplementation of antifreeze 20% CPLL was effective in improving the post-warm survival of isolated rat pancreatic islets when vitrification solution containing 30% EG was used.

Transgenic silkworm technology has enabled the biological properties of silk fibroin protein to be altered by fusion to recombinant bioactive proteins. However, few studies have reported the fabrication of genetically modified fibroin proteins into three-dimensional spongy structures to serve as scaffolds for tissue engineering. We generated a transgenic silkworm strain that produces fibroin fused to basic fibroblast growth factor (bFGF) and processed the fibroin into a spongy structure using a simple freeze/thaw method. NIH3T3 mouse embryonic fibroblasts grown on bFGF-fused fibroin sponges proliferated and spread out well, showing half the population doubling time of cells cultured on wild-type fibroin sponges. Furthermore, the number of primary rabbit articular chondrocytes growing on bFGF-fused fibroin sponges was around five-times higher than that of the wild-type control at 3-days post cell-seeding. As the physical properties of wild-type and bFGF-fused fibroin sponges were almost identical, it is suggested that bFGF fused to fibroin retained its biological activity, even after the bFGF-fused fibroin was fabricated into the spongy structure. The bFGF-fused fibroin sponge has the potential for widespread application in the field of tissue engineering, and the method of fabricating this structure could be applicable to other recombinant bioactive fibroin proteins. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 82–93, 2016.

Objective To investigate the effects of wearing complete dentures on pharyngeal shape for swallowing in edentulous older people. Background In the absence of complete dentures, edentulous older people often lose the occlusal support necessary to position the mandible, which leads to an anterosuperior shift of the mandible during swallowing. This may result in pharyngeal shape changes effecting swallowing function in older people. However, the details of this phenomenon are currently unclear. Materials and methods Participants were 17 older edentulous volunteers. Cone-beam computed tomography imaging was performed with the participant in the seated position and wearing (i) both maxillary and mandibular dentures, (ii) maxillary dentures only and (iii) no dentures. During imaging, participants were instructed to keep their mouth closed to the mandibular position determined in advance during swallowing for each denture-wearing condition. The volume, height and average cross-sectional area of the velopharynx and oropharynx were measured, and the positions of the epiglottis and mandible were recorded. Results While the vertical height of the oral cavity and pharynx significantly decreased, the volume and average cross-sectional area of the oropharynx significantly increased when dentures were not worn (p

The influence of autoclaving on the properties of silk fibroin fabrics (SF fab s) was evaluated. High-performance liquid chromatography revealed that the molecular weight (Mw) of the fibroin molecule in SF fab s decreased as the treatment temperature and time increased, which suggests that the fibroin molecule in the fabrics was thermal degraded. Additionally, differential scanning calorimetry experiments revealed a shift of the endothermic peak to higher temperature with increasing treatment temperature and time, which indicates an improvement in the thermal stability of the fibroin molecule in the autoclaved fabrics. Furthermore, 13 C cross-polarization/magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis revealed that the intensity ratios for the β-sheet and random-coil peaks fluctuated during autoclaving. The NMR analysis also revealed the presence of an unknown structure in the autoclaved SF fab s under certain conditions. The changes in the Mws and degradation temperatures for the autoclaved SF fab s are assumed to be induced by the structural changes observed via NMR. Consequently, autoclaving is considered to be an effective technique for modifying the secondary structure and properties of SF fab s with high β-sheet contents using only water and heat without added reagents.