Unwillingness to cooperate with COVID-19 contact tracing in Japan.

OBJECTIVES: Contact tracing for COVID-19 relies heavily on the cooperation of individuals with authorities to provide information of contact persons. However, few studies have clarified willingness to cooperate and motivation to provide information for contact tracing. This study sought to describe willingness to cooperate and motivation to report contact persons for COVID-19 contact tracing among citizens in Japan, and to assess any associated sociodemographic factors. STUDY DESIGN: Cross-sectional study. METHODS: This was an online-based survey using quota sampling. Participants were asked about their willingness to cooperate in reporting contacts for COVID-19 contact tracing if they tested positive. Participants also responded to questions regarding their reasons for cooperating or not cooperating and provided sociodemographic data. Multiple logistic regression analysis was performed to clarify associations between sociodemographic factors and willingness to cooperate. RESULTS: This study included 2844 participants. The proportion of participants who were not willing to cooperate in reporting contacts was 27.6%, with their main reasons being concerns about causing trouble for the other person and being criticised for revealing their names. Willingness to cooperate was lower among men, young adults and those with an educational level less than a university degree. CONCLUSIONS: To improve the effectiveness of contact tracing, educational campaigns, such as reducing the fear and stigma associated with COVID-19, may be important. Furthermore, it is essential to understand that individuals may have contacts whom they do not wish to disclose to others and to be considerate when handling such situations.

Different changes in the biomarker C-terminal telopeptides of type II collagen (CTX-II) following intra-articular injection of high molecular weight hyaluronic acid and oral non-steroidal anti-inflammatory drugs in patients with knee osteoarthritis: a multi-center randomized controlled study.

OBJECTIVES: We previously reported, based on a multicenter randomized-control study, that the efficacy of intra-articular injections of hyaluronic acid (IA-HA) was not inferior to that of oral non-steroidal anti-inflammatory drugs (NSAIDs) in patients with knee osteoarthritis (OA). However, the molecular effects on the pathophysiology of knee OA remain unclear. C-terminal telopeptides of type II collagen (CTX-II) is reported to primarily originate from the interface between articular cartilage and subchondral bone, which is a site of potential remodeling in OA. We performed a predefined sub-analysis of the previous study to compare the changes of urinary CTX-II (uCTX-II) in response to IA-HA to those in response to NSAID for knee OA. DESIGN: A total of 200 knee OA patients were registered from 20 hospitals and randomized to receive IA-HA (2,700 kDa HA, 5 times at 1-week intervals) or NSAID (loxoprofen sodium, 180 mg/day) for 5 weeks. The uCTX-II levels were measured before and after treatment. RESULTS: The uCTX-II levels were significantly increased by IA-HA treatment (337.7 ± 193.8 to 370.7 ± 234.8 ng/µmol Cr) and were significantly reduced by NSAID treatment (423.2 ± 257.6 to 370.3 ± 250.9 ng/µmol Cr). The %changes of uCTX-II induced by IA-HA (11.6 ± 29.5%) and NSAID (-9.0 ± 26.7%) was significantly different (between-group difference: 20.6, 95% confidence intervals: 10.6 to 30.6). CONCLUSIONS: While both IA-HA and NSAID improved symptoms of knee OA, uCTX-II levels were increased by IA-HA and reduced by NSAIDs treatment, suggesting these treatments may improve symptoms of knee OA through different modes of action.

Aerotaxis and aerokinesis of Dictyostelium discoideum under hypoxic microenvironments.

Although spatiotemporal changes of oxygen in a microenvironment are known to affect the cellular dynamics of various eukaryotes, the details are not fully understood. Here, we describe the aerotaxis and aerokinesis of Dictyostelium discoideum (Dd), which has long been employed as a model organism for eukaryotic cells. We developed a microfluidic device capable of time-lapse observation of cultured cells while controlling oxygen concentrations in microchannels. Migratory behaviors of Dd were observed and quantitatively evaluated under an oxygen concentration gradient from 0% to 21% O2, as well as in various uniform oxygen conditions. In a hypoxic region within the oxygen concentration gradient, Dd migrated toward regions of higher oxygen concentration at increased velocity, which was independent of cell density. Observed under uniform oxygen concentrations of 1%, 2%, 3%, and 21%, the migration velocity of Dd increased significantly in hypoxic environments of 2% O2 or less. Thus, Dd shows aerotaxis, directed by the oxygen concentration gradient, and simultaneously shows aerokinesis, changing the migration velocity according to the oxygen concentration itself.

Association of residual gastric acid secretion with persistent symptoms in gastroesophageal reflux disease patients receiving standard-dose proton pump inhibitor therapy.

BACKGROUND: Although a third of gastroesophageal reflux disease (GERD) patients are refractory to proton pump inhibitor (PPI) therapy, the underlying mechanism of the refractoriness remains unclear. We compared the level of gastric acid suppression during PPI treatment between responders and non-responders by directly measuring gastric acid secretion in GERD patients taking PPIs. METHODS: Seventy-five consecutive patients receiving standard-dose PPI therapy for GERD were prospectively recruited, irrespective of persistent GERD symptoms. They were asked about their GERD symptoms using a validated questionnaire, and simultaneously underwent both a routine endoscopic examination and a gastric acid secretory testing using an endoscopic gastrin test. Associations between residual gastric acid secretion during PPI treatment and persistent GERD symptoms were analyzed by a logistic regression analysis. RESULTS: Overall, 26 of 75 (34.7%) patients were judged to be positive for persistent GERD symptoms. The patients with and without persistent symptoms showed similar gastric acid secretion levels (1.3 [1.3] mEq/10 min vs. 1.4 [2.0] mEq/10 min). Sufficient gastric acid suppression, defined as < 0.6, was not significantly associated with persistent GERD symptoms (odds ratio 1.1, 95% confidence interval 0.40-3.5). CONCLUSIONS: This study provided solid evidence to support that the gastric acid suppression level during PPI treatment does not differ between patients with and without persistent GERD symptoms. The insignificant role of residual gastric acid in the persistent GERD symptoms suggests that the use of medications other than those that enhance gastric acid inhibitory effects would be an essential approach for the management of PPI-refractory GERD.

Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution.

The near-Earth asteroid (162173) Ryugu is thought to be a primitive carbonaceous object that contains hydrated minerals and organic molecules. We report sample collection from Ryugu's surface by the Hayabusa2 spacecraft on 21 February 2019. Touchdown images and global observations of surface colors are used to investigate the stratigraphy of the surface around the sample location and across Ryugu. Latitudinal color variations suggest the reddening of exposed surface material by solar heating and/or space weathering. Immediately after touchdown, Hayabusa2's thrusters disturbed dark, fine grains that originate from the redder materials. The stratigraphic relationship between identified craters and the redder material indicates that surface reddening occurred over a short period of time. We suggest that Ryugu previously experienced an orbital excursion near the Sun.

Outcome of maintenance systemic chemotherapy with drug-free interval for metastatic urothelial carcinoma.

OBJECTIVE: Aiming to achieve long-term disease control, maintenance systemic chemotherapy (MSC) with a 1-3-month drug-free interval is continued in selected patients. We report our experience of MSC for metastatic urothelial carcinoma (UC). METHODS: Of 228 metastatic UC patients treated with systemic chemotherapy, 40 (17.5%, 40/228) had continuously undergone MSC. Data on the regimen, cycle number, and reason for the discontinuation of MSC were also collected. We analyzed OS from the initiation of MSC until death or the last follow-up, using the log-rank test to assess the significance of differences. RESULTS: The median number of cycles of chemotherapy was 6, and the responses were CR in 6, PR in 20, SD in 13, and PD in 1 before MSC. Gemcitabine plus CDDP or carboplatin was mainly performed as MSC (70%, 28/40). MSC was repeated quarterly in 30 (75%, 30/40), every two months in 8 (20%, 8/40), and with other intervals in 2 (5%, 2/40). Overall, a median of 3.5 cycles (range: 1-29) of MSC was performed. The reason for the discontinuation of MSC was PD in 24 (60%, 24/40), favorable disease control in 9 (22.5%, 9/40), and myelosuppression in 3 (7.5%, 3/40), and for other reasons in 2 (5%, 2/40). MSC was ongoing in 2 (5%, 2/40). The median OS was 27 months from the initiation of MSC. PS0 (P = 0.0169), the absence of lung metastasis (P = 0.0387), and resection of the primary site (P = 0.0495) were associated with long-term survival after MSC. CONCLUSIONS: In selected patients, long-term systemic chemotherapy could be performed with a drug-free interval. Our maintenance strategy with cytotoxic drugs may become one of the treatment options for long-term disease control.

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes.

The near-Earth carbonaceous asteroid 162173 Ryugu is thought to have been produced from a parent body that contained water ice and organic molecules. The Hayabusa2 spacecraft has obtained global multicolor images of Ryugu. Geomorphological features present include a circum-equatorial ridge, east-west dichotomy, high boulder abundances across the entire surface, and impact craters. Age estimates from the craters indicate a resurfacing age of [Formula: see text] years for the top 1-meter layer. Ryugu is among the darkest known bodies in the Solar System. The high abundance and spectral properties of boulders are consistent with moderately dehydrated materials, analogous to thermally metamorphosed meteorites found on Earth. The general uniformity in color across Ryugu's surface supports partial dehydration due to internal heating of the asteroid's parent body.

Kidney enlargement and multiple liver cyst formation implicate mutations in PKD1/2 in adult sporadic polycystic kidney disease.

Distinguishing autosomal-dominant polycystic kidney disease (ADPKD) from other inherited renal cystic diseases in patients with adult polycystic kidney disease and no family history is critical for correct treatment and appropriate genetic counseling. However, for patients with no family history, there are no definitive imaging findings that provide an unequivocal ADPKD diagnosis. We analyzed 53 adult polycystic kidney disease patients with no family history. Comprehensive genetic testing was performed using capture-based next-generation sequencing for 69 genes currently known to cause hereditary renal cystic diseases including ADPKD. Through our analysis, 32 patients had PKD1 or PKD2 mutations. Additionally, 3 patients with disease-causing mutations in NPHP4, PKHD1, and OFD1 were diagnosed with an inherited renal cystic disease other than ADPKD. In patients with PKD1 or PKD2 mutations, the prevalence of polycystic liver disease, defined as more than 20 liver cysts, was significantly higher (71.9% vs 33.3%, P = .006), total kidney volume was significantly increased (median, 1580.7 mL vs 791.0 mL, P = .027) and mean arterial pressure was significantly higher (median, 98 mm Hg vs 91 mm Hg, P = .012). The genetic screening approach and clinical features described here are potentially beneficial for optimal management of adult sporadic polycystic kidney disease patients.

Effect of brefelamide on proliferation of 1321N1 human astrocytoma cells induced by glial cell line-derived neurotrophic factor.

Malignant gliomas are highly resistant to chemotherapy and radiation and more effective options for treatment are urgently needed. We reported previously that the aromatic amide brefelamide, which is isolated from methanolic extracts of the cellular slime molds Dictyostelium giganteum and D. brefeldianum, hinders cellular proliferation in a glioma model utilizing 1321N1 human astrocytoma cells. Herein, we examined the mechanisms underlying the inhibition of 1321N1 cell proliferation by brefelamide. Glial cell line-derived neurotrophic factor (GDNF) was found to enhance the rate of proliferation of serum-free cultured 1321N1 cells, but did not affect proliferation in PC12 cells. Brefelamide pretreatment inhibited GDNF-induced cell proliferation and expression of rearranged during transfection (RET). GDNF enhanced the phosphorylation of extracellular signal-regulated kinase (ERK), AKT, and c-jun-N-terminal kinase (JNK); however, brefelamide pretreatment inhibited these effects. Brefelamide also reduced the expression of GDNF mRNA and GDNF secretion. Together, the findings from this study indicate that brefelamide inhibits the proliferation of 1321N1 cell via several mechanisms including reduced GDNF receptor expression and GDNF secretion, and reduced phosphorylation of ERK, AKT, and JNK.

Alkaloids from aerial parts of Annona senegalensis against Streptococcus mutans.

Antimicrobial potential of medicinal plants have been explored extensively these days. This study was carried out to evaluate the antibacterial potential from aerial parts of plant, called 'Annona senegalensis' and its constituents. Bioassay guided fractionation led to the isolation of four metabolites, (+)-catechin (1), (-)-anonaine (2), (-)-asimilobine (3) and (+)-nornantenine (4). This is the first report on the isolation of compounds 1, 3 and 4 from this plant. Compounds 2 and 4 showed good activity, whereas 1 and 3 displayed weak inhibition against Streptococcus mutans (ATCC 25175). The results showed that compound 2 and 3 showed significant activity with a minimum inhibition concentration (MIC) of 0.12 and 0.25 mg/mL, respectively. The present study reports for the first time the antibacterial activity of the extract of A. senegalensis and its constituents. As S. mutans is a rather resistant bacteria, the MIC obtained during the present study is significant.

A giant polymer lattice in a polymer-stabilized blue phase liquid crystal.

Ultrasmall-angle synchrotron X-ray scattering measurements showed that a three-dimensional polymer lattice of a few 100 nm order with body-centered cubic O(8-) symmetry was formed in a polymer-stabilized blue phase liquid crystal. We obtained clear experimental evidence that the polymer chains condensed selectively in the disclinations within the blue phase during photo-polymerization of monomers in the blue phase.

MR imaging of subcallosal artery infarct causing amnesia after surgery for anterior communicating artery aneurysm.

BACKGROUND AND PURPOSE: During surgery to treat an aneurysm in the anterior communicating artery, injury to the subcallosal artery, a perforator of the anterior communicating artery, may lead to infarction that produces basal forebrain amnesia after surgery. Our purpose was to examine whether 3D MR imaging can detect subcallosal artery infarction in patients with amnesia after surgery for an anterior communicating artery aneurysm. MATERIALS AND METHODS: We evaluated 3D-T2-weighted MR images obtained a median of 4 months after treatment of anterior communicating artery aneurysm for the presence of infarcted foci in 10 consecutive patients with postoperative amnesia. Because the subcallosal artery and its neighboring perforator, the recurrent artery of Heubner, were considered the most easily affected vessels during that surgery, we focused mainly on 8 regions of the subcallosal artery territory per hemisphere and 5 regions of the recurrent artery of Heubner territory per hemisphere. RESULTS: All 10 patients had infarcts in the territory of the subcallosal artery (median, 9 regions per patient), and most were bilateral (9 of 10 patients). Five patients had additional infarcted foci in the territory of the recurrent artery of Heubner (median, 1 region per patient), all unilateral. Among the regions perfused by the subcallosal artery, the column of the fornix was involved in all patients; the anterior commissure, in 9; and the paraterminal gyrus, in 8 patients. CONCLUSIONS: 3D MR imaging revealed subcallosal artery infarction, the distribution of which was mostly bilateral, presumably owing to the unpairedness of that artery, in patients with postoperative amnesia after anterior communicating artery aneurysm repair.

MyD88 is essential for alveolar bone loss induced by Aggregatibacter actinomycetemcomitans lipopolysaccharide in mice.

Aggregatibacter actinomycetemcomitans is a Gram-negative bacteria highly associated with localized aggressive periodontitis. The recognition of microbial factors, such as lipopolysaccharide from A. actinomycetemcomitans ((Aa)LPS), in the oral environment is made mainly by surface receptors known as Toll-like receptors (TLR). TLR4 is the major LPS receptor. This interaction leads to the production of inflammatory cytokines by myeloid differentiation primary-response protein 88 (MyD88) -dependent and -independent pathways, which may involve the adaptor Toll/interleukin-1 receptor-domain-containing adaptor inducing interferon-ß (TRIF). The aim of this study was to assess the involvement of MyD88 in alveolar bone loss induced by (Aa)LPS in mice. C57BL6/J wild-type (WT) mice, MyD88, TRIF or TRIF/MyD88 knockout mice received 10 injections of Aa LPS strain FDC Y4 (5 µg in 3 µl), in the palatal gingival tissue of the right first molar, every 48 h. Phosphate-buffered saline was injected in the opposite side and used as control. Animals were sacrificed 24 h after the 10th injection and the maxillae were removed for macroscopic and biochemical analyses. The injections of Aa LPS induced significant alveolar bone loss in WT mice. In the absence of MyD88 or TRIF/MyD88 no bone loss induced by (Aa)LPS was observed. In contrast, responses in TRIF(-/-) mice were similar to those in WT mice. Diminished bone loss in the absence of MyD88 was associated with fewer TRAP-positive cells and increased expression of osteoblast markers, RUNX2 and osteopontin. There was also reduced tumor necrosis factor-α production in MyD88(-/-) mice. There was less osteoclast differentiation of hematopoietic bone marrow cells from MyD88(-/-) mice after (Aa)LPS stimulation. Hence, the signaling through MyD88 is pivotal for (Aa)LPS-induced osteoclast formation and alveolar bone loss.

Body fat percentage as a marker of new-onset diabetes mellitus after kidney transplantation.

BACKGROUND: New-onset diabetes after transplantation (NODAT) is a serious metabolic complication that can follow kidney transplantation. Several risk factors, including obesity, have been related to NODAT development. Obesity is defined as an excessive accumulation of body fat, and body fat percentage (BF%) has been commonly measured by different techniques, including bioelectrical impedance analysis. However, the correlation between an increase in BF% and the development of NODAT during outpatient follow-up has not yet been explored. We aimed to elucidate the association between BF% changes and the development of NODAT. METHODS: We performed a retrospective study involving 45 patients without diabetes who underwent kidney transplantation in our hospital between March 2008 and December 2010. We compared the BF% and demographic variables of patients who did and did not develop NODAT during follow-up. RESULTS: Four patients (8.9%) developed NODAT during a mean follow-up period of 30.3 months. The post-transplantation increase in BF% was much higher in NODAT+ patients than the NODAT- patients. Univariate analysis indicated that the rate of increase in BF% was a risk factor for NODAT (hazard ratio [HR], 1.08 [1.02-1.18]; P < .005). CONCLUSIONS: A large increase in BF% may be a risk factor for NODAT. These findings underline the importance of routine BF% measurements in medical practice.

Outcomes of renal transplantation after end-stage renal disease due to diabetic nephropathy: a single-center experience.

BACKGROUND: Diabetic nephropathy is the most common cause of end-stage renal disease (ESRD) worldwide. However, data on renal transplantation outcomes in diabetic nephropathy among Japanese remain inadequate. This retrospective study was conducted to summarize our renal transplantation experience in diabetic ESRD patients. METHODS: We retrospectively studied 462 patients who underwent kidney transplantation between 1989 and 2011, including 23 with diabetic ESRD (DM group) and 439 with nondiabetic ESRD (NDM group). We compared demographic and clinical variables between these 2 groups. RESULTS: Mean age was higher in the DM group (48.0 vs 38.2 years; P < .001), and there was no significant difference in gender or donor source. The 1-, 3-, and 5-year graft survival rates in the DM and NDM groups were 100% vs 98.3% (ns), 82.4% vs 94.9% (P < .05), and 66.7% vs 90.3% (P < .01), respectively. The 1-, 3-, and 5-year patient survival rates were 95.0% vs 96.5% (ns), 88.2% vs 95.2% (ns), and 84.6% vs 92.9% (ns), respectively. One patient (4.3%) in the DM group and 6 (1.4%) in the NDM group died from cardiovascular disease during the follow-up period (ns). The incidence of rejection did not differ between the DM and NDM groups. There were no significant differences in the total infection rate or the urinary tract infection rate. CONCLUSIONS: Renal transplantation in diabetic ESRD patients yields good results in terms of patient survival and complications, suggesting that renal transplantation can be performed in these patients and should become a more established treatment option.

Severity-based treatment for Japanese patients with MPO-ANCA-associated vasculitis: the JMAAV study.

We (JMAAV [Japanese patients with MPO-ANCA-associated vasculitis] Study Group) performed a prospective, open-label, multi-center trial to evaluate the usefulness of severity-based treatment in Japanese patients with myeloperoxidase-anti-neutrophil cytoplasmic antibodies (MPO-ANCA)-associated vasculitis. Patients with MPO-ANCA-associated vasculitis received a severity-based regimen according to the appropriate protocol: low-dose corticosteroid and, if necessary, cyclophosphamide or azathioprine in patients with mild form; high-dose corticosteroid and cyclophosphamide in those with severe form; and the severe-form regimen plus plasmapheresis in those with the most severe form. We followed up the patients for 18 months. The primary end points were the induction of remission, death, and end-stage renal disease (ESRD). Fifty-two patients were registered, and 48 patients were enrolled in this study (mild form, n = 23; severe form, n = 23; most severe form, n = 2). Among the 47 patients who received the predefined therapies, 42 achieved remission within 6 months, 5 died, and 1 developed ESRD. Disease flared up in 8 of the 42 patients with remission during the 18-month follow-up period. The JMAAV trial is the first prospective trial for MPO-ANCA-associated vasculitis to be performed in Japan. The remission and death rates were comparable to those in several previous clinical trials performed in western counties. The regimen employed in this trial was tailor-made based on patients' disease severity and disease type, and it seems that standardization can be consistent with treatment choices made according to severity.

Phylogenetic study of the species within the family Streptomycetaceae.

Species of the genus Streptomyces, which constitute the vast majority of taxa within the family Streptomycetaceae, are a predominant component of the microbial population in soils throughout the world and have been the subject of extensive isolation and screening efforts over the years because they are a major source of commercially and medically important secondary metabolites. Taxonomic characterization of Streptomyces strains has been a challenge due to the large number of described species, greater than any other microbial genus, resulting from academic and industrial activities. The methods used for characterization have evolved through several phases over the years from those based largely on morphological observations, to subsequent classifications based on numerical taxonomic analyses of standardized sets of phenotypic characters and, most recently, to the use of molecular phylogenetic analyses of gene sequences. The present phylogenetic study examines almost all described species (615 taxa) within the family Streptomycetaceae based on 16S rRNA gene sequences and illustrates the species diversity within this family, which is observed to contain 130 statistically supported clades, as well as many unsupported and single member clusters. Many of the observed clades are consistent with earlier morphological and numerical taxonomic studies, but it is apparent that insufficient variation is present in the 16S rRNA gene sequence within the species of this family to permit bootstrap-supported resolution of relationships between many of the individual clusters.

Br-DIF-1 accelerates dimethyl sulphoxide-induced differentiation of P19CL6 embryonic carcinoma cells into cardiomyocytes.

BACKGROUND AND PURPOSE: Stem cell transplantation therapy is a promising option for treatment of severe ischaemic heart disease. Dimethyl sulphoxide (DMSO) differentiates P19CL6 embryonic carcinoma cells into cardiomyocyte-like cells, but with low differentiation capacity. To improve the degree of this differentiation, we have assessed several derivatives of the differentiation-inducing factor-1 (DIF-1), originally found in the cellular slime mould Dictyostelium discoideum, on P19CL6 cells. EXPERIMENTAL APPROACH: P19CL6 cells were cultured with each derivative and 1% DMSO for up to 16 days. Differentiation was assessed by measuring the number of beating and non-beating aggregates, and the expression of genes relevant to cardiac tissue. The mechanism of action was investigated using a T-type Ca(2+) channel blocker. KEY RESULTS: Of all the DIF-1 derivatives tested only Br-DIF-1 showed any effects on cardiomyocyte differentiation. In the presence of 1% DMSO, Br-DIF-1 (0.3-3 µM) significantly and dose-dependently increased the number of spontaneously beating aggregates compared with 1% DMSO alone, by day 16. Expression of mRNA for T-type calcium channels was significantly increased by Br-DIF-1 + 1% DMSO compared with 1% DMSO alone. Mibefradil (a T-type Ca(2+) channel blocker; 100 nM) and a small interfering RNA for the T-type Ca(2+) channel both significantly decreased the beating rate of aggregates induced by Br-DIF-1 + 1% DMSO. CONCLUSIONS AND IMPLICATIONS: Br-DIF-1 accelerated the differentiation, induced by 1% DMSO, of P19CL6 cells into spontaneously beating cardiomyocyte-like cells, partly by enhancing the expression of the T-type Ca(2+) channel gene.

Endoscopic management of malignant biliary obstruction by means of covered metallic stents: primary stent placement vs. re-intervention.

BACKGROUND AND STUDY AIMS: Recent progress in chemotherapy has prolonged the survival of patients with malignant biliary strictures, leading to increased rates of stent occlusion. Occlusion of covered metallic stents now occurs in about half of all patients with malignant biliary strictures. The removal of metallic stents followed by placement of a second stent has been attempted, but outcomes remain controversial. The aim of the current study was to evaluate the effectiveness and safety of the primary placement and secondary placement (re-intervention) of covered metallic stents and to assess the feasibility and safety of stent removal. PATIENTS AND METHODS: The study included 186 patients with unresectable malignant biliary strictures who underwent primary stent placement between October 2001 and March 2010.  Covered biliary self-expandable metal stents (SEMSs) were removed in 39 of these patients, and 36 underwent re-intervention. The patency times, occlusion rates of the first stent and re-intervention, success rates of stent removal, and complications were investigated. RESULTS: Covered SEMSs were placed in 186 patients. The median patency time of the first stent was 352 days. Stent occlusion occurred in 48.9 % of the patients and was mainly caused by debris or food residue (37 %), dislocation (19 %), and migration with hyperplasia (19 %). Stent removal was attempted in 50 patients and was successful without complication in 39 (78 %). Most of the patients in whom stent removal was unsuccessful had migration with hyperplasia. The median patency time of the second stent was 263 days. The stent patency time did not significantly differ between the first and the second stent. CONCLUSIONS: Covered SEMSs could be safely removed at the time of stent occlusion. Patency rates were similar for initial stent placement and re-intervention.