Prevention of esophageal stenosis via in situ cross-linkable alginate/gelatin powder in a new submucosal exfoliation model in rats.

Endoscopic submucosal dissection (ESD) for the treatment of esophageal mucosal lesions often leads to postoperative stenosis, causing difficulty in swallowing, known as dysphagia. In this study, we developed an in situ cross-linkable powder composed of alginate, gelatin, transglutaminase (TG), and calcium chloride ions (Ca2+), which can be administered through a 1.5 m-long and 3.2 mm-diameter endoscopic instrument channel. The powdered mixture of alginate and gelatin quickly formed a hydrogel by absorbing body fluids and was cross-linked by TG and Ca2+, which adhered ex vivo to porcine submucosal layers for over 2 weeks. In addition, we developed a new submucosal exfoliation model in rats that induced severe stenosis, similar to the ESD-induced stenosis models in clinical practice. When administered to the new rat model, the powder system effectively reduced the severity of esophageal stenosis based on body weight change monitoring, anatomical findings, and histological analysis. The body weight of the rats was maintained at the initial weight on postoperative day 14 (POD14), and epithelialization on POD7 and 14 improved to almost 100%. Additionally, collagen accumulation and the number of α-SMA-positive cells decreased due to powder administration. Therefore, these findings indicate that the in situ cross-linkable powder can prevent esophageal stenosis after ESD.

Hemostatic Capability of a Novel Tetra-Polyethylene Glycol Hydrogel.

BACKGROUND: TetraStat is a tetra-armed polyethylene glycol (PEG) hydrogel. It is a synthetic sealant that solidifies instantly in response to pH changes. This study aimed to evaluate the hemostatic effect of TetraStat through experiments evaluating future clinical applications. METHODS: We used TetraStat, oxidized regenerated cellulose (SURGICEL®), and fibrinogen and thrombin sealant patch (TachoSil®) using in vitro and in vivo experiments. For the in vitro experiment, a closed circulatory system filled with phosphate-buffered saline under high pressure was used. Needle punctures were created and closed using the various sealants. For the in vivo experiment, rat venae cavae were punctured with 18- and 20-gauge (G) needles, and hemorrhage was allowed to occur for several seconds. A porous PEG sponge soaked with TetraStat was applied as a hemostatic system. Hemostasis outcomes were compared among the various concentrations (40-100 g/L) of TetraStat, SURGICEL, and TachoSil. RESULTS: The punctured holes in the prosthetic graft were successfully sealed with TetraStat in 1 min. The success rate of hemostasis with TetraStat for the punctured holes in the rat vena cava was dose-dependent. TetraStat was effective in sealing the holes created with a 20 G needle at all concentrations; however, the holes created with an 18 G needle could be sealed only when the concentration ≥60 g/L. Hemostasis using SURGICEL or TachoSil was less successful and sometimes required up to 5 min. CONCLUSIONS: TetraStat has a high hemostatic ability. A porous PEG sponge soaked with TetraStat is a useful choice for effective hemostasis during massive hemorrhage.

The feasibility of a novel injectable hydrogel for protecting artificial gastrointestinal ulcers after endoscopic resection: an animal pilot study.

Recently, covering materials for protecting post-endoscopic ulcers are being developed using hydrogels. Existing hydrogels are not ideal coating materials because it is difficult to control their physical properties. Therefore, we conducted an animal pilot study to investigate the protective effect of a novel ulcer coating material, whose physical properties can be easily controlled and designed. We applied the novel injectable hydrogel to artificial ulcers induced on the gastric mucosa of rats. Rats were assigned to the hydrogel or the control group. To measure the protective effect of hydrogel on ulcers, the perforation rate, ulcer diameter, and ulcer area were evaluated 48 h after gel application. As secondary endpoints, we assessed the residual rate of the hydrogel at the bottom of the ulcer, performed histological analysis, and analyzed adverse events associated with hydrogel. The perforation rate was significantly lower (16% vs. 75%) and the mean diameter of ulcers was significantly smaller (5.4 ± 1.8 mm vs. 7.8 ± 2.8 mm) in the hydrogel group. Histopathological findings revealed the inflammatory cell count was significantly higher in the control group. Our novel hydrogel showed a protective effect on artificial gastric ulcers in a rat model.

Preliminary study of eye tracking to investigate the differences in gaze behaviors depending on the experience of neuroendovascular therapy.

BACKGROUND: Neuroendovascular therapy is now the choice for the management of many neurovascular pathologies, and physicians with endovascular skills are in high demand. In addition to the traditional method of practicing hand movements to learn skills, a new strategy of practicing eye movements to learn skills is also attracting attention. This preliminary study explored the differences in gaze behavior depending on experience with endovascular procedures to be facilitated in future skill training in neuroendovascular therapy. METHODS: Four physicians with experience of 3-412 neuroendovascular procedures wore eye-tracking devices during coil embolization of swine cervical arteries. Gaze metrics with direct correlations to the expertise of endovascular procedures were explored. RESULTS: Gaze metrics with a positive direct correlation to experience included the proportion of fixation durations (PFD) in the screen area and the native images. Those with a negative direct correlation included the PFD in the off-screen area and the roadmap images and the average fixation durations in the off-screen and coil areas. During the parent artery occlusion procedure with detachable coils, more experienced operators preferred to look at native images rather than roadmap images and that less experienced operators tended to look down at their hands more frequently. CONCLUSION: This preliminary study demonstrated the feasibility of eye tracking to identify the differences in gaze behavior depending on the experience of endovascular procedures and may guide future eye-tracking studies in neuroendovascular therapy.

Alternative plasticizer, 4-cyclohexene-1,2-dicarboxylic acid dinonyl ester, for blood containers with protective effects on red blood cells and improved cold resistance.

Di (2-ethylhexyl) phthalate (DEHP), a typical plasticizer used for polyvinyl chloride (PVC), is eluted from PVC-made blood containers and protects against red blood cell (RBC) hemolysis. However, concerns have arisen regarding the reproductive and developmental risks of DEHP in humans, and the use of alternative plasticizers for medical devices has been recommended worldwide. In this study, we propose that the use of a novel plasticizer, 4-cyclohexene-1,2-dicarboxylic acid dinonyl ester (DL9TH), could help produce more useful and safe blood containers. PVC sheet containing DL9TH and di (2-ethylhexyl) 4-cyclohexene-1,2-dicarboxylate (DOTH) provides comparable or superior protective effects to RBCs relative to PVC sheet containing DEHP or di-isononyl-cyclohexane-1,2-dicarboxylate (DINCH® , an alternative plasticizer that has been used in PVC sheets for blood containers). The total amount of plasticizer eluted from DOTH/DL9TH-PVC sheets is nearly the same as that eluted from DEHP-PVC sheets. In addition, DOTH/DL9TH-PVC has better cold resistance than DEHP- and DINCH® -PVC sheets. In vitro and in vivo tests for biological safety based on International Organization for Standardization guidelines (10993 series) suggest that the DOTH/DL9TH-PVC sheet can be used safely. Subchronic toxicity testing of DL9TH in male rats in accordance with the principles of Organisation for Economic Co-operation and Development Test Guideline 408 showed that DL9TH did not induce adverse effects up to the highest dose level tested (717 mg/kg body weight/day). There were no effects on testicular histopathology and sperm counts, and no indications of endocrine effects: testosterone, thyroid-stimulating hormone, follicle-stimulating hormone, and 17ß-estradiol were unchanged by the treatment, compared with the control group. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1052-1063, 2018.

Co-lyophilized Aspirin with Trehalose Causes Less Injury to Human Gastric Cells and Gastric Mucosa of Rats.

BACKGROUND: Aspirin is one of the most popular NSAIDs worldwide because of its anti-inflammatory and anticoagulant effects, and however, gastrointestinal injury remains a major complication. We previously reported co-lyophilized aspirin/trehalose (Lyo A/T) decreased the aspirin-induced gastric lesions in dogs. AIM: This study investigated the mechanism of gastroprotective effects of trehalose in vitro and in vivo. METHODS: The apoptotic assays were performed in a human gastric carcinoma cell line, which was treated with aspirin, mixed aspirin/trehalose (Mix A/T) or Lyo A/T. Gastric ulcer severity was examined after oral administration of drugs in rats. In addition, the mucosal tissue apoptotic status in drug-treated rats was evaluated. Molecular dynamics simulations and laser Raman spectroscopy were performed in order to examine the molecular properties of Lyo A/T. RESULTS: DNA fragmentation was detected in AGS cells that were treated with aspirin and Mix A/T, but not in the Lyo A/T-treated cells. There were fewer apoptotic cells in the Lyo A/T-treated cells than in the other cells. Gastric injury was reduced in rats that received oral Lyo A/T compared with the others, while PGE2 synthesis was equally decreased in all groups. TUNEL assay and immunohistochemistry of cleaved caspase-3 in the mucosal tissues also revealed that Lyo A/T treatment induced less apoptosis than the others. The Lyo A/T spectrum showed clear differences in several Raman bands compared with that of Mix A/T. CONCLUSIONS: Our data showed that co-lyophilization of aspirin with trehalose reduced gastric injury, potentially through suppression of aspirin-induced mucosal cell apoptosis while retaining its anti-inflammatory effects.

Messenger RNA delivery of a cartilage-anabolic transcription factor as a disease-modifying strategy for osteoarthritis treatment.

Osteoarthritis (OA) is a chronic degenerative joint disease and a major health problem in the elderly population. No disease-modifying osteoarthritis drug (DMOAD) has been made available for clinical use. Here we present a disease-modifying strategy for OA, focusing on messenger RNA (mRNA) delivery of a therapeutic transcription factor using polyethylene glycol (PEG)-polyamino acid block copolymer-based polyplex nanomicelles. When polyplex nanomicelles carrying the cartilage-anabolic, runt-related transcription factor (RUNX) 1 mRNA were injected into mouse OA knee joints, OA progression was significantly suppressed compared with the non-treatment control. Expressions of cartilage-anabolic markers and proliferation were augmented in articular chondrocytes of the RUNX1-injected knees. Thus, this study provides a proof of concept of the treatment of degenerative diseases such as OA by the in situ mRNA delivery of therapeutic transcription factors; the presented approach will directly connect basic findings on disease-protective or tissue-regenerating factors to disease treatment.

Dermal cell damage induced by topical application of non-steroidal anti-inflammatory drugs is suppressed by trehalose co-lyophilization in ex vivo analysis.

Topical administration of non-steroidal anti-inflammatory drugs (NSAIDs) is generally considered safer than oral administration, although the former can occasionally induce cutaneous irritation. We hypothesized that the cutaneous irritation by topical NSAIDs might be suppressed by trehalose, which has protective effects on biological membranes. Using the three-dimensional cultured human skin model, Living Skin Equivalent-high, we found that cutaneous damage due to NSAIDs was reduced by concomitant use of trehalose and that this effect of trehalose was reinforced by co-lyophilization of NSAIDs with trehalose. The anti-inflammatory effect of co-lyophilized NSAIDs with trehalose was comparable to that seen with NSAIDs alone in a rat model. Our results suggest that co-lyophilization of NSAIDs with trehalose might be a novel procedure that can help prevent NSAIDs-induced skin irritation.

Possible involvement of neuropeptide Y in photo-induced suppression of growth hormone pulses.

It is well established that growth hormone (GH) is secreted in a pulsatile manner. Although the GH pulse-generating mechanism is not fully understood, we have previously reported that neuropeptide Y (NPY) profiles in the cerebrospinal fluid were negatively correlated with serum GH pulses. In addition, it is known that photic stimulation suppresses GH pulses for a certain period of time. In the present study, to investigate the involvement of NPY in regulating GH pulse generation, NPY gene expression in the arcuate nucleus (ARC) of the hypothalamus in rats was analyzed at around the lights on. First, we confirmed that GH pulses did not occur for around 1.5 hr after the start of the light phase. Then, we analyzed the activity of neurons and expression of NPY mRNA 1 hr before and 0.5 and 2 hr after lights on. Both the activity of neurons, which was evaluated by immunohistochemical detection for phosphorylated-cAMP response element binding protein (pCREB), and NPY mRNA levels in the caudal ARC were higher at 0.5 hr after lights on than the other two time points, while pCREB-positive cell numbers in the rostral ARC remained unchanged throughout the experimental period. In addition, NPY immunoreactivity in the periventricular nucleus (PeVN) was also higher at 0.5 hr after lights on than the other time points. These results suggest that NPY neurons in the caudal ARC projecting to the PeVN play a role in inhibiting GH pulses at the commencement of the light phase.

Trehalose treatment suppresses inflammation, oxidative stress, and vasospasm induced by experimental subarachnoid hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) frequently results in several complications, including cerebral vasospasm, associated with high mortality. Although cerebral vasospasm is a major cause of brain damages after SAH, other factors such as inflammatory responses and oxidative stress also contribute to high mortality after SAH. Trehalose is a non-reducing disaccharide in which two glucose units are linked by α,α-1,1-glycosidic bond, and has been shown to induce tolerance to a variety of stressors in numerous organisms. In the present study, we investigated the effect of trehalose on cerebral vasospasm, inflammatory responses, and oxidative stress induced by blood in vitro and in vivo. METHODS: Enzyme immunoassay for eicosanoids, pro-inflammatory cytokines, and endothelin-1, and western blotting analysis for cyclooxygenase-2, inducible nitric oxide synthase, and inhibitor of NF-κB were examined in macrophage-like cells treated with hemolysate. After treatment with hemolysate and hydrogen peroxide, the levels of lipid peroxide and amounts of arachidonic acid release were also analyzed. Three hours after the onset of experimental SAH, 18 Japanese White rabbits received an injection of saline, trehalose, or maltose into the cisterna magna. Angiographic and histological analyses of the basilar arteries were performed. In a separate study, the femoral arteries from 60 rats were exposed to fresh autologous blood. At 1, 3, 5, 7, 10, and 20 days after treatment, cryosections prepared from the femoral arteries were histologically analyzed. RESULTS: When cells were treated with hemolysate, trehalose inhibited the production of several inflammatory mediators and degradation of the inhibitor of NF-κB and also suppressed the lipid peroxidation, the reactive oxygen species-induced arachidonic acid release in vitro. In the rabbit model, trehalose produced an inhibitory effect on vasospasm after the onset of experimental SAH, while maltose had only a moderate effect. When the rat femoral arteries exposed to blood were investigated for 20 days, histological analysis revealed that trehalose suppressed vasospasm, inflammatory response, and lipid peroxidation. CONCLUSIONS: These data suggest that trehalose has suppressive effects on several pathological events after SAH, including vasospasm, inflammatory responses, and lipid peroxidation. Trehalose may be a new therapeutic approach for treatment of complications after SAH.