Development of a Remote Displacement Measuring Laser System for Bridge Inspection.

Measuring displacement is essential for assessing the safety of bridges. Non-contact sensors such as vision sensors can precisely measure displacement but may be expensive or incapable of micro-scale measurement at a low cost, unlike contact displacement sensors, which are economical but challenging to install. This study proposes an economical, remote non-contact sensor system. The system comprises a laser beam transmitter and a light receiver, deriving the displacement based on the position where the laser beam is irradiated to the light-receiving surface. To measure this, the light receiver was installed at the measurement point and included a wireless communicator to transmit the displacement data. A displacement experiment was conducted to evaluate the performance. The results confirmed that precise displacement measurements were possible at a resolution of 100 µm. For bridge load tests, a light receiver under a bridge was installed, laser beams irradiated to the light-receiving surface from a distance, and the displacement was measured for each test and compared with the values measured by a conventional contact sensor. The results were highly consistent with those of the existing sensor, indicating that the proposed sensor system applies to bridge loading tests and the safety diagnosis for various structures.

Loss of SP-A in the Lung Exacerbates Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a devastating and common chronic lung disease that is pathologically characterized by the destruction of lung architecture and the accumulation of extracellular matrix in the lung. Previous studies have shown an association between lung surfactant protein (SP) and the pathogenesis of IPF, as demonstrated by mutations and the altered expression of SP in patients with IPF. However, the role of SP in the development of lung fibrosis is poorly understood. In this study, the role of surfactant protein A (SP-A) was explored in experimental lung fibrosis induced with a low or high dose of bleomycin (BLM) and CRISPR/Cas9-mediated genetic deletion of SP-A. Our results showed that lung SP-A deficiency in mice promoted the development of fibrotic damage and exacerbated inflammatory responses to the BLM challenge. In vitro experiments with murine lung epithelial LA-4 cells demonstrated that in response to transforming growth factor-ß1 (TGF-ß1), LA-4 cells had a decreased protein expression of SP-A. Furthermore, exogenous SP administration to LA-4 cells inhibited the TGF-ß1-induced upregulation of fibrotic markers. Overall, these findings suggest a novel antifibrotic mechanism of SP-A in the development of lung fibrosis, which indicates the therapeutic potential of the lung SP-A in preventing the development of IPF.

Protective effects of therapeutic hypothermia on renal injury in an asphyxial cardiac arrest rat model.

Cardiac arrest (CA) is a leading cause of mortality worldwide. Most of post-resuscitation related deaths are due to post-cardiac arrest syndrome (PCAS). After cardiopulmonary resuscitation (CPR), return of spontaneous circulation (ROSC) leads to renal ischemia-reperfusion injury, also known as PCAS. Many studies have focused on brain and heart injuries after ROSC, but renal failure has largely been ignored. Therefore, we investigated the protective effects of therapeutic hypothermia (TH) on asphyxial CA-induced renal injury in rats. Thirty rats were randomly divided into five groups: 1) the control group (sham); 2) the normothermic CA (nor.); 3) a normothermic CA group that received TH immediately within 2 h after CPR (Hypo. 2 hrs); 4) a normothermic CA group that received TH within 4 h after CPR (Hypo. 4 hrs); and 5) a normothermia CA group that received TH within 6 h after CPR (Hypo. 6 h). One day after CPR, all rats were sacrificed. Compared with the normothermic CA group, the TH groups demonstrated significantly increased survival rate (P < 0.05); decreased serum blood urea nitrogen, creatinine, and lactate dehydrogenase levels; and lower histological damage degree and malondialdehyde concentration in their renal tissue. Terminal deoxynucleotidyl transferase dUTP nick end labeling stain revealed that the number of apoptotic cells significantly decreased after 4 h and 6 h of TH compared to the results seen in the normothermic CA group. Moreover, TH downregulated the expression of cyclooxygenase-2 in the renal cortex compared to the normothermic CA group one day after CPR. These results suggest that TH exerts anti-apoptotic, anti-inflammatory, and anti-oxidative effects immediately after ROSC that protect against renal injury.

Correction: Akanda, M.R., et al., Anti-Inflammatory and Gastroprotective Roles of Rabdosia inflexa through Downregulation of Pro-Inflammatory Cytokines and MAPK/NF-κB Signaling Pathways. Int. J. Mol. Sci. 2018, 19, 584.

The authors wish to make the following corrections to this paper [...].

Anti-Inflammatory and Gastroprotective Roles of Rabdosia inflexa through Downregulation of Pro-Inflammatory Cytokines and MAPK/NF-κB Signaling Pathways.

Globally, gastric ulcer is a vital health hazard for a human. Rabdosia inflexa (RI) has been used in traditional medicine for inflammatory diseases. The present study aimed to investigate the protective effect and related molecular mechanism of RI using lipopolysaccharide (LPS)-induced inflammation in RAW 246.7 cells and HCl/EtOH-induced gastric ulcer in mice. We applied 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), nitric oxide (NO), reactive oxygen species (ROS), histopathology, malondialdehyde (MDA), quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry (IHC), and Western blot analyses to evaluate the protective role of RI. Study revealed that RI effectively attenuated LPS-promoted NO and ROS production in RAW 246.7 cells. In addition, RI mitigated gastric oxidative stress by inhibiting lipid peroxidation, elevating NO, and decreasing gastric inflammation. RI significantly halted elevated gene expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), inducible nitric oxide synthetase (iNOS), and cyclooxygenase-2 (COX-2) in gastric tissue. Likewise, RI markedly attenuated the mitogen-activated protein kinases (MAPKs) phosphorylation, COX-2 expression, phosphorylation and degradation of inhibitor kappa B (IκBα) and activation of nuclear factor kappa B (NF-κB). Thus, experimental findings suggested that the anti-inflammatory and gastroprotective activities of RI might contribute to regulating pro-inflammatory cytokines and MAPK/NF-κB signaling pathways.

The effect of feedback in attention training on Attention Bias to Threat in individuals with Sluggish Cognitive Tempo.

BACKGROUND AND OBJECTIVES: This study was conducted to identify the characteristics of attentional bias of individuals with Sluggish Cognitive Tempo (SCT) and how Attention Bias to Threat (ABT) changes when feedback was provided in attention training. METHODS: First, a dot probe task was conducted to confirm the ABT of the SCT feedback group (N = 27) and SCT no feedback group (N = 25), and healthy control group (N = 30) before intervention. Thereafter, a VR-based attention training was conducted three times with feedback or no feedback. Finally, a dot probe task was executed again. RESULTS: The SCT groups showed a higher ABT than the healthy control group. A result of the attention training, the reaction time of disengage was significantly reduced when provided feedback. In addition, it was confirmed that the ABT of the SCT group that received feedback, was significantly reduced. LIMITATIONS: First, the only stimulus used to examine the ABT was the angry face, and the reaction time to other threatening facial expressions was not confirmed. Second, attention training was conducted three times, but further studies are needed on the effect of the duration of training on the magnitude of effect. CONCLUSIONS: This study identified ABT associated with internalizing symptoms of SCT and suggests that attention training with immediate and continuous feedback is needed to reduce ABT.

A cancer-specific variant of the SLCO1B3 gene encodes a novel human organic anion transporting polypeptide 1B3 (OATP1B3) localized mainly in the cytoplasm of colon and pancreatic cancer cells.

OATP1B3 is a member of the OATP (organic anion transporting polypeptides) superfamily, responsible for mediating the transport of numerous endogenous and xenobiotic substances. Although initially reported to be exclusively expressed in the liver, several studies reported that OATP1B3 is frequently expressed in multiple types of cancers and may be associated with differing clinical outcomes. However, a detailed investigation on the expression and function of OATP1B3 protein in cancer has been lacking. In this study, we confirmed that colon and pancreatic cancer cells express variant forms of OATP1B3, different from OATP1B3 wild-type (WT) expressed in the normal liver. OATP1B3 variant 1 (V1), the most prevalent form among the variants, contains alternative exonic sequences (exon 2a) instead of exons 1 and 2 present in OATP1B3 WT. The translated product of OATP1B3 V1 is almost identical to OATP1B3 WT, with exception to the first 28 amino acids at the N-terminus. Exogenous expression of OATP1B3 V1 revealed that OATP1B3 V1 undergoes post-translational modifications and proteasomal degradation to a differing extent compared to OATP1B3 WT. OATP1B3 V1 showed only modest transport activity toward cholecystokin-8 (CCK-8, a prototype OATP1B3 substrate) in contrast to OATP1B3 WT showing a markedly efficient uptake of CCK-8. Consistent with these results, OATP1B3 V1 was localized mainly in the cytoplasm with a much lower extent of trafficking to the surface membrane compared to OATP1B3 WT. In summary, our results demonstrate that colon and pancreatic cancer cells express variant forms of OATP1B3 with only limited transport activity and different subcellular localization compared to OATP1B3 WT. These observed differences at the molecular and functional levels will be important considerations for further investigations of the biological and clinical significance of OATP1B3 expression in cancer.

Development of peptide-based reversing agents for p-glycoprotein-mediated resistance to carfilzomib.

Carfilzomib is a novel class of peptidyl epoxyketone proteasome inhibitor and has demonstrated promising activity in multiple clinical trials to treat patients with multiple myeloma and other types of cancers. Here, we investigated molecular mechanisms underlying acquired resistance to carfilzomib and a potential strategy to restore cellular sensitivity to carfilzomib. H23 and DLD-1 cells (human lung and colon adenocarcinoma cell lines) with acquired resistance to carfilzomib displayed marked cross-resistance to YU-101, a closely related proteasome inhibitor, and paclitaxel, a known substrate of Pgp. However, carfilzomib-resistant cells remained sensitive to bortezomib, a clinically used dipeptide with boronic acid pharmacophore. In accordance with these observations, carfilzomib-resistant H23 and DLD-1 cells showed marked upregulation of P-glycoprotein (Pgp) as compared to their parental controls, and coincubation with verapamil, a Pgp inhibitor, led to an almost complete restoration of cellular sensitivity to carfilzomib. These results indicate that Pgp upregulation plays a major role in the development of carfilzomib resistance in these cell lines. In developing a potential strategy to overcome carfilzomib resistance, we as a proof of concept prepared a small library of peptide analogues derived from the peptide backbone of carfilzomib and screened these molecules for their activity to restore carfilzomib sensitivity when cotreated with carfilzomib. We found that compounds as small as dipeptides are sufficient in restoring carfilzomib sensitivity. Taken together, we found that Pgp upregulation plays a major role in the development of resistance to carfilzomib in lung and colon adenocarcinoma cell lines and that small peptide analogues lacking the pharmacophore can be used as agents to reverse acquired carfilzomib resistance. Our findings may provide important information in developing a potential strategy to overcome drug resistance.

The effect of feedback in virtual attention training on orienting attention in individuals with sluggish cognitive tempo.

OBJECTIVE: This study was conducted to assess the effectiveness of feedback in a virtual attention training program to improve the attentional characteristics of sluggish cognitive tempo (SCT). METHOD: The SCT group (N = 60) and control group (N = 30) were identified, and the attention network test-revised (ANT-R) was performed to measure attention characteristics. Based on this result, a virtual reality (VR) feedback attention training program was developed to improve the efficiency of engagement and disengagement of attention in SCT. Sixty participants with SCT were recruited and grouped into two conditions: VR feedback (n = 30) and no-feedback (n = 30) conditions. RESULTS: The results show that the VR attention training program with feedback significantly improves the attention-orienting network. CONCLUSION: This suggests that it is necessary to provide immediate feedback for effective attention training for SCT and continuous intervention may be possible when feedback is provided together.

Therapeutic hypothermia effect on asphyxial cardiac arrest-induced renal ischemia/reperfusion injury via change of Nrf2/HO-1 levels.

The present study aimed to investigate the renoprotective effect of therapeutic hypothermia (TH) on renal ischemia-reperfusion injury (RI/RI) induced by asphyxial cardiac arrest (CA) in rats. A total of 48 male rats were randomly divided into five groups: i) Sham (n=6); ii) Normothermia + CA (Normo.) (n=14); iii) Normo. and 2 h of TH after return of spontaneous circulation (ROSC) (n=12); iv) Normo. and 4 h of TH after ROSC (n=9); and v) Normo. and 6 h of TH after ROSC (n=7). All rats except the Sham group underwent asphyxia CA and were sacrificed 1 day after ROSC. The survival rate increased from 42.8% in the Normo. group to 50, 66.6 and 85.7% in the groups with 2, 4 and 6 h of TH after CA, respectively. TH attenuated the histopathological changes of the renal tissues following ROSC and the levels of blood urea nitrogen, serum creatinine and malondialdehyde in renal tissues. On immunohistochemistry, the relative optical density of nuclear erythroid-related factor-2 (Nrf2) and heme oxygenase (HO-1) expression in renal tissues increased in the Normo. group compared with that in the Sham group and exhibited further significant increases at 6 h of TH after ROSC. In conclusion, TH attenuated renal injury and increased the expression of Nrf2 and HO-1 in a TH treatment time-dependent manner.

Electrochemical fabrication of Pt-Au-WO3 electrodes for direct methanol fuel cell.

Pt-Au-WO3 ternary electrodes with various compositions were synthesized by electrochemical method from a mixture of H2PtCl6 aqueous solution, HAuCl4 aqueous solution, and W-peroxo complex. Their electrocatalytic activities for methanol oxidation were investigated. Film composition was controlled by varying the concentration of each component in electrolytes. Morphology and compositional analyses of the synthesized films were performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The catalytic activity and initial behavior of current density for methanol oxidation of the synthesized films were measured using cyclic voltammetry (CV) and chronoamperometry (CA) in a mixture of 0.5 M H2SO4 and 0.5 M CH3OH solution. Electrocatalytic activity for CO oxidation was also evaluated in 0.5 M H2SO4 solution. The activities of various electrodes for methanol oxidation were found to be strongly dependent on film composition. Pt-Au-WO3 electrodes exhibited higher activity for CO oxidation than pure Pt. The addition of proper amount of Au and WO3 significantly improved catalytic activity for methanol oxidation.

Fabrication of mesoporous cobalt oxide (Co3O4) film by electrochemical method for electrochemical capacitor.

Mesoporous cobalt oxide (Co3O4) films were deposited on ITO coated glass substrates by electrodeposition from an aqueous CoSO4 solution using CTAB (cetyltrimethylammonium bromide) as the templating agent. The structures of the synthesized films were characterized by X-ray diffraction, and X-ray photoelectron spectroscopy. The presence of mesoporosity was confirmed by transmission electron microscopy and small angle X-ray diffraction analyses. The mesoporous structures of the synthesized films were found to be strongly dependent on the deposition conditions, such as deposition voltage, deposition time, temperature and concentration of templating agent. Cyclic voltammetry and discharging curves were used to examine the electrochemical properties as a capacitor. The mesoporous films prepared with CTAB templating showed a much higher specific capacitance and current density than the nonporous electrode prepared without CTAB templating.

A high mobility group B-1 box A peptide combined with an artery wall binding peptide targets delivery of nucleic acids to smooth muscle cells.

The TAT-high mobility group box-1 A box peptide (TAT-HMGB1A) has been reported previously to be able to deliver DNA into cells without cytotoxicity. In this study, an artery wall smooth muscle cell-targeting carrier was developed using TAT-HMGB1A combined with an artery wall binding peptide (ABP). For the production of ABP linked TAT-HMGB1A (TAT-HMGB1A-ABP), pET15b-TAT-HMGB1A-ABP was constructed by inserting the ABP cDNA into pET15b-TAT-HMGB1A. TAT-HMGB1A-ABP was expressed in E. coli and purified by Nickel chelate chromatography. Gel retardation assays showed that TAT-HMGB1A-ABP formed a complex with the plasmid at or above a 5:1 weight ratio (peptide:plasmid). At a 20:1 weight ratio, the zeta-potential was approximately 25 mV and the particle size was approximately 120 nm. TAT-HMGB1A-ABP had the highest transfection efficiency in A7R5 smooth muscle cells at a weight ratio of 20:1. TAT-HMGB1A-ABP exhibited higher transfection efficiency in A7R5 cells than PLL or TAT-HMGB1A, while TAT-HMGB1A-ABP had lower transfection efficiencies in Hep3B hepatoma, 293 kidney, NIH3T3 fibroblast, and Raw264.7 macrophage cells compared with PLL. Together, these results suggest that the ABP moiety of the peptide increased transfection efficiency specifically in smooth muscle cells. In a competition assay, the transfection efficiency of TAT-HMGB1A-ABP in A7R5 cells was reduced by the addition of free ABP. MTT assays showed that TAT-HMGB1A-ABP did not produce any cytotoxicity in A7R5 cells. Therefore, TAT-HMGB1A-ABP may be useful for a targeting gene delivery to smooth muscle cells.

Augmentation of erythropoietin enhancer-mediated hypoxia-inducible gene expression by co-transfection of a plasmid encoding hypoxia-inducible factor 1alpha for ischemic tissue targeting gene therapy.

Therapeutic angiogenesis with gene encoding vascular endothelial growth factor (VEGF) is a potential treatment for ischemic diseases. However, VEGF expression should be tightly regulated to avoid side effects such as tumor growth. Previously, our group developed the erythropoietin (Epo) enhancer-SV40 promoter system for hypoxia-specific gene expression. In the present study, the activity of the Epo enhancer-SV40 promoter system was further enhanced without significant decrease in its specificity by co-transfection of the hypoxia-inducible factor 1alpha (HIF1alpha) gene. pSV-HIF1alpha was constructed by the insertion of the HIF1alpha cDNA into pSI. At a 1:1 ratio, co-transfection of pSV-HIF1alpha and pEpo-SV-Luc increased the promoter activity of the Epo enhancer-SV40 promoter system, showing at least three times higher gene expression under hypoxia as compared with the pEpo-SV-Luc single-plasmid transfection. Furthermore, co-transfection showed significant hypoxia specificity. Also, co-transfection of pEpo-SV-VEGF with pSV-HIF1alpha showed the enhanced VEGF expression without loss of hypoxia specificity, as compared with pEpo-SV-VEGF single-plasmid transfection. Furthermore, pSV-HIF1alpha induced the endogenous hypoxia-responsive genes such as angiopoietin-1, which would be beneficial for therapeutic angiogenesis. Therefore, with hypoxia specificity and higher gene expression, co-transfection of pSV-HIF1alpha and pEpo-SV-VEGF may be useful for ischemia targeting gene therapy.

Purification of antibody fragments for the reduction of charge variants using cation exchange chromatography.

Recently, antibody fragments have been studied as therapeutic agents because they lack Fc effector function while having affinity similar to their original monoclonal antibody and can be produced using E. coli. Antibody fragments can be purified using affinity chromatography in the capture step, although they need a polishing step because of product-related impurities, mainly charge variants. Unlike monoclonal antibodies, few studies exist regarding the separation of charge variants in antibody variants. In this study, an efficient separation of charge variant method was assessed using a cation exchange chromatography resin with salt and a pH gradient. The SP ImpRes resin and pH gradient exhibited the most effective separation potency using combinations of resin and the separation method. The antibody fragment that did not undergo the charge variant separation process exhibited a difference in the tertiary structure of the protein and in vivo pharmacokinetics. However, the antibody fragment was similar to the reference protein when the charge variant separation process was performed. These results are expected to support efficient charge variant separation of antibody fragments and to be applied to the industrial production of therapeutic antibody fragments.

Fibronectin-Derived Oligopeptide Stimulates Osteoblast Differentiation Through a Bone Morphogenic Protein 2-Like Signaling Pathway.

BACKGROUND: In previous studies by the authors, it was demonstrated that a fibronectin (FN)-derived oligopeptide, termed F20, stimulates osteoblast differentiation in vitro and bone formation in vivo. However, the fundamental molecular mechanism by which F20 stimulates osteogenesis remains unknown. Therefore, in this study the molecular mechanism underlying the effect of F20 in osteoblast differentiation is investigated. METHODS: The role of F20 in osteoblast differentiation was examined using mouse bone-marrow-derived ST2 cell line. The effect of Smad1/5 was determined following small interfering RNA knockdown. Runt-related transcription factor (Runx) 2, alkaline phosphatase (Alp), and osteocalcin (Oc) mRNA levels were determined by quantitative real-time polymerase chain reaction, and their transcriptional activation was assessed using luciferase reporter assays. Extracellular signal-regulated kinase (ERK) phosphorylation was visualized via immunoblotting. RESULTS: Synthetic oligopeptide F20 stimulated expression of bone marker genes Runx2, Alp, and Oc in ST2 cells via Smad and ERK or mitogen-activated protein kinase signaling pathways as did bone morphogenic protein 2 (BMP2). Furthermore, Runx2 acted as a transcription factor during F20-induced osteoblast differentiation. CONCLUSIONS: Collectively, these results indicate that F20 induces osteoblast differentiation with a pattern similar to that mediated by BMP2 signaling pathway. The authors' previous data also showed that FN-derived oligopeptide improved wound healing, and it is suggested that F20 might serve as a therapeutic biomolecule to facilitate periodontal tissue regeneration.

Electrospinning of chitin nanofibers: degradation behavior and cellular response to normal human keratinocytes and fibroblasts.

An electrospinning method was used to fabricate chitin nanofibrous matrices for biodegradability and cell behavior tests. The morphology of as-spun chitin nanofibers (Chi-N) and commercial chitin microfibers (Beschitin W; Chi-M) was investigated by scanning electron microscopy. From the image analysis, the average diameters of Chi-N and Chi-M were 163 nm and 8.77 microm, respectively. During in vitro degradation for 15 days, the degradation rate of Chi-N was faster than that of Chi-M, likely due to higher surface area of Chi-N. Chi-N that was grafted into rat subcutaneous tissue had almost degraded within 28 days, and no inflammation could be seen on the nanofiber surfaces or in the surrounding tissues (except in the early stage wound). To assay and compare the cytocompatibility and cell behavior with Chi-N and Chi-M, cell attachment and spreading of normal human keratinocytes and fibroblasts seeded on chitin matrices and the interaction between cells and chitin fibers were studied. Relatively high cell attachment and spreading of all the cells tested were observed on Chi-N in comparison to Chi-M, and Chi-N treated with type I collagen significantly promoted the cellular response. Our results indicate that the Chi-N, alone or with extracellular matrix proteins (particularly type I collagen), could be potential candidates for the cell attachment and spreading of normal human keratinocytes and fibroblasts. This property of Chi-N might be particularly useful for wound healing and regeneration of oral mucosa and skin.

Biomimetic Approach to Stimulate Osteogenesis on Titanium Implant Surfaces Using Fibronectin Derived Oligopeptide.

Our previous studies demonstrated that a recombinant fibronectin (FN)-derived oligopeptide that we named F20 stimulated osteoblast adhesion, proliferation, and differentiation in vitro and in vivo. In the present study, we used a synthetic oligopeptide and investigated the osteogenic potential of F20 coating on titanium discs, to stimulate superior osseointegration for dental implant surface modification. Surface characteristic analysis of titanium was performed by confocal laser scanning microscopy (CLSM) observation. Synthetic F20 was coated onto the machined or SLA titanium discs by an adsorption procedure. ST2 cells were seeded on the titanium discs. We evaluated cell adhesion with SEM and CLSM observation, cell proliferation with picogreen assay, and osteoblast differentiation with real-time PCR, ALP activity assay, immunoblot assay and ALP staining. FITC-labeled F20 coating on the discs was detected by fluorescence, showing good F20 adsorption and different coating patterns according to the surface roughness. In the SEM and CLSM observations, cells were well attached on the machined surface and greater stress fiber formation was seen on discs coated with F20 than on other discs. F20 stimulated cellular proliferation, as well as osteoblast differentiation through the extracellular signalregulated kinase (Erk) signaling pathway. These cellular responses to F20 were slightly better on the machined titanium surface than the SLA surface. These results suggest that F20 promotes osteogenesis through the Erk pathway and is a suitable biomolecule for surface modification of dental implants for improved osseointegration.

Self-expandable covered metallic esophageal stent impregnated with beta-emitting radionuclide: an experimental study in canine esophagus.

PURPOSE: A specially designed self-expandable covered metallic stent impregnated with the beta-emitting radioisotope 166Ho (166Ho, energy: 1.85 and 1.76 MeV, T12: 26.8 h) was developed at our institute for the purpose of intraluminal palliative brachytherapy, as well as for treating malignant esophageal stricture and swallowing difficulty. The aim of this study was to evaluate the tissue response to brachytherapy and the safety of the radioactive metallic stent with regard to the normal canine esophagus before clinical application. METHODS AND MATERIALS: 166Ho was impregnated into the polyurethane membrane (50 micron thickness) covering the outer surface of a self-expandable metallic stent (diameter, 18 mm; length, 40 mm). Stents with radioactivity 4.0-7.8 mCi (Group A, n = 15), 1.0-1.8 mCi (Group B, n = 5), and 0.5-0.7 mCi (Group C, n = 5) were placed in the esophagi of 25 healthy beagle dogs, and the stents were tightly anchored surgically to prevent migration. The estimated radiation dose calculated by Monte Carlo simulation was 194-383 Gy in Group A, 48-90 Gy in Group B, and 23-32 Gy in Group C. The dogs were killed 8-12 weeks after insertion of the stents, and histologic examinations of the esophageal walls were performed. RESULTS: In Group A, 3 of 15 dogs died of wound infection, so specimens were obtained from only 12 dogs; all 12 cases showed esophageal stricture with mucosal ulceration. Microscopically, severe fibrosis and degeneration of the muscular propria were found in 3 dogs, complete fibrosis of the entire esophageal wall was found in 7 dogs, and esophageal fibrosis with radiation damage within periesophageal soft tissue was found in 2 dogs. However, esophageal perforation did not develop, despite extremely high radiation doses. In Group B, glandular atrophy and submucosal fibrosis were found, but the muscular layer was intact. In Group C, no histologic change was found in 3 dogs, but submucosal inflammation and glandular atrophy with intact mucosa were found in 2 dogs. CONCLUSIONS: A radioactive, self-expandable covered metallic stent can be used as an alternative therapeutic modality for the palliative treatment of malignant esophageal stricture.

166Ho-coated balloon for vascular brachytherapy.

A simple procedure was developed for coating the surface of a conventional percutaneous transluminal coronary angioplasty balloon angioplasty catheter with 166Ho. The absorbed dose delivered by the surface-coated catheter is twice that of a similar catheter filled with a solution containing the same activity of 166Ho. Leakage tests show that <0.6% of the coated activity is removable from the surface of the catheter. The coated catheter removes the risk of release of the 166Ho into the body as a result of rupture of the balloon, and also reduces the radiation exposure to staff.