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138
result(s) for
"Okazaki, Keisuke"
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A Bacterial Biosensor for Oxidative Stress Using the Constitutively Expressed Redox-Sensitive Protein roGFP2
by
Inayat-Hussain, Salmaan H.
,
Okazaki, Keisuke
,
Koutsaftis, Apostolos
in
Bacterial Physiological Phenomena
,
Bioassays
,
Biosensing Techniques
2010
A highly specific, high throughput-amenable bacterial biosensor for chemically induced cellular oxidation was developed using constitutively expressed redox-sensitive green fluorescent protein roGFP2 in E. coli (E. coli-roGFP2). Disulfide formation between two key cysteine residues of roGFP2 was assessed using a double-wavelength ratiometric approach. This study demonstrates that only a few minutes were required to detect oxidation using E. coli-roGFP2, in contrast to conventional bacterial oxidative stress sensors. Cellular oxidation induced by hydrogen peroxide, menadione, sodium selenite, zinc pyrithione, triphenyltin and naphthalene became detectable after 10 seconds and reached the maxima between 80 to 210 seconds, contrary to Cd2+, Cu2+, Pb2+, Zn2+ and sodium arsenite, which induced the oxidation maximum immediately. The lowest observable effect concentrations (in ppm) were determined as 1.0 x 10−7 (arsenite), 1.0 x 10−4 (naphthalene), 1.0 x 10−4 (Cu2+), 3.8 x 10−4 (H2O2), 1.0 x 10−3 (Cd2+), 1.0 x 10−3 (Zn2+), 1.0 x 10−2 (menadione), 1.0 (triphenyltin), 1.56 (zinc pyrithione), 3.1 (selenite) and 6.3 (Pb2+), respectively. Heavy metal-induced oxidation showed unclear response patterns, whereas concentration-dependent sigmoid curves were observed for other compounds. In vivo GSH content and in vitro roGFP2 oxidation assays together with E. coli-roGFP2 results suggest that roGFP2 is sensitive to redox potential change and thiol modification induced by environmental stressors. Based on redox-sensitive technology, E. coli-roGFP2 provides a fast comprehensive detection system for toxicants that induce cellular oxidation.
Journal Article
Alterative expression of the collagenase and adhesion molecules in the highly metastatic clones of human colonic cancer cell lines
1998
Human colonic carcinoma cell lines, KM12C, KM12SM and KM12L4, were previously established and their in vivo metastatic potentials have been well evaluated. The highly metastatic cell lines KM12SM and KM12L4 were derived from the parental low metastatic cell line KM12C in vivo. To evaluate the metastatic behavior of these cell lines in vitro, we examined colony formation on monolayers of the pulmonary arterial endothelial (CPAE) cells. On day 4, the highly metastatic cell lines showed an approximately 2-fold increase in number of colonies on CPAE cell monolayers relative to the parental KM12C cell line. To investigate what evidence is correlated with their metastatic and invasive abilities, Northern blot analysis and flow cytometry were performed in all cell lines. According to the results of Northern blot analysis, the levels of matrix metalloproteinase (MMP)-2 and c-met mRNA expression were increased in highly metastatic cell lines as compared with the parental cell line. We also examined the cell-surface expression of several adhesion molecules by flow cytometry. The levels of expression of sialyl Lewisa antigen (sLe(a)) in KM12SM and KM12L4 were twice higher than that in KM12C. However, the levels of expression of E-cadherin in KM12SM and KM12L4 were decreased to half that in KM12C. The alterative expression of the collagenase and adhesion molecules might contribute to their metastatic/invasive abilities of these cell lines both in vivo and in vitro.
Journal Article
MR4MR: Mixed Reality for Melody Reincarnation
by
Tokui, Nao
,
Kobayashi, Atsuya
,
Okazaki, Keisuke
in
Context
,
Digital computers
,
Helmet mounted displays
2022
There is a long history of an effort made to explore musical elements with the entities and spaces around us, such as musique concrète and ambient music. In the context of computer music and digital art, interactive experiences that concentrate on the surrounding objects and physical spaces have also been designed. In recent years, with the development and popularization of devices, an increasing number of works have been designed in Extended Reality to create such musical experiences. In this paper, we describe MR4MR, a sound installation work that allows users to experience melodies produced from interactions with their surrounding space in the context of Mixed Reality (MR). Using HoloLens, an MR head-mounted display, users can bump virtual objects that emit sound against real objects in their surroundings. Then, by continuously creating a melody following the sound made by the object and re-generating randomly and gradually changing melody using music generation machine learning models, users can feel their ambient melody \"reincarnating\".
Multicentre, retrospective study of the efficacy and safety of nivolumab for recurrent and metastatic salivary gland carcinoma
2020
Although immune-checkpoint inhibitors (ICIs) are effective against various cancers, little is known regarding their role in salivary gland carcinoma (SGC) treatment. Therefore, we evaluated the efficacy and safety of nivolumab monotherapy in patients with recurrent and/or metastatic SGC. In this multicentre retrospective study, nivolumab (240 mg) was administered every 2 weeks. The overall response rate (ORR), progression-free survival (PFS), overall survival (OS), and safety were examined; the correlation between treatment outcomes and clinicopathological factors was analysed. Twenty-four patients were enrolled; the most common histopathology was salivary duct carcinoma. Eleven tumours were PD-L1-positive; no tumour was microsatellite instability-high. The ORR was 4.2%, and the median PFS and OS were 1.6 and 10.7 months, respectively. One patient continued nivolumab for 28 months without disease progression. One patient showed grade 4 increase in creatine phosphokinase levels and grade 3 myositis. Biomarker analysis revealed significantly increased OS in patients with performance status of 0; modified Glasgow prognostic score of 0; low neutrophil-to-lymphocyte ratio, lactate dehydrogenase, and C-reactive protein; and high lymphocyte-to-monocyte ratio and in patients who received systemic therapy following nivolumab. Although nivolumab’s efficacy against SGC was limited, some patients achieved long-term disease control. Further studies are warranted on ICI use for SGC.
Journal Article
Immunohistochemical staining patterns of p53 predict the mutational status of TP53 in oral epithelial dysplasia
2022
Next-generation sequencing of oral squamous cell carcinoma (OSCC) has revealed
TP53
as the most frequently mutated gene in OSCC mutually exclusive with human papillomavirus infection. Oral epithelial dysplasia (OED) is defined as a precancerous lesion of OSCC by the current World Health Organization (WHO) classification; therefore, it is assumed that
TP53
mutations occur in early precancerous conditions such as OED. Here, we conducted an integrated analysis of
TP53
, including whole coding sequencing of
TP53
, FISH analysis of the 17p13.1 locus, and immunohistochemical analysis for p53 (p53-IHC), in 40 OED cases. We detected 20 mutations in 16 (40%) OED cases, and four cases, each harbored two mutations. FISH analysis revealed six of 24 cases (25%) had a deletion on 17p13.1, and four cases had concurrent
TP53
mutations and 17p13.1 deletion (2-hit). Also, the increased frequency of
TP53
mutations in higher degrees of OED implies acquisition of the mutation is a major event toward OSCC. p53-IHC revealed that overall cases could be categorized into four patterns that correlate well with the mutational status of
TP53
. Especially, two patterns, broad p53 expression type (pattern HI) and p53 null type (pattern LS), strongly correlated with a missense mutation and nonsense mutation, respectively. Furthermore, seven of the 40 cases progressed to SCC, and six of these seven cases presented pattern HI or LS. Therefore, patterns HI and LS have a high risk for malignant transformation if excisional treatment is not performed irrespective of the dysplasia grade. Although the current WHO classification mainly focuses on morphological criteria for the diagnosis of OED, interobserver discrepancy appears in some instances of the OED diagnosis. Our immunohistochemical analysis supports a more accurate pathological diagnosis for OED in cases of low dysplastic changes or of differential diagnosis with non-dysplastic lesions.
Journal Article
Determination and analysis of singlet oxygen quantum yields of talaporfin sodium, protoporphyrin IX, and lipidated protoporphyrin IX using near-infrared luminescence spectroscopy
2020
In photodynamic therapy (PDT), singlet oxygen (
1
O
2
) is the main species responsible for promoting tumor cell death. The determination of the quantum yield (Φ
Δ
) of a photosensitizer (PS) is important for dosimetry. The purpose of this paper is to quantify the
1
O
2
generated by the PS by near-infrared spectroscopy (NIRS). The Φ
Δ
of different PS species were measured by the detection of near-infrared
1
O
2
luminescence. From the measurement results, the Φ
Δ
of talaporfin sodium, protoporphyrin IX (PpIX), and lipidated PpIX (PpIX lipid) were measured as 0.53, 0.77, and 0.87, respectively. In addition, the Φ
Δ
values of PpIX in a hypoxic and oxic solution were evaluated, since tumors are associated with regions of hypoxia. The measured Φ
Δ
indicated a same value at high (DO: 20%) and low (DO: 1%) oxygen concentrations. Using the measured Φ
Δ
, the amount of
1
O
2
generated by the PSs was estimated using [
1
O
2
] = D*Φ
Δ
, where D* is the total excited PS concentration. The generated
1
O
2
amounts were little different at the high and the low oxygen concentrations, and the generated
1
O
2
amount for each PS was different depending on each Φ
Δ
. The NIRS measurement determined the Φ
Δ
of talaporfin sodium, PpIX, and PpIX lipid. The quantitative evaluation based on the measured Φ
Δ
will support the development of PDT treatment monitoring and design.
Journal Article
Medial meniscus posterior root repair reduces the extruded meniscus volume during knee flexion with favorable clinical outcome
by
Xue, Haowei
,
Ozaki, Toshifumi
,
Hiranaka, Takaaki
in
Biomedical materials
,
Clinical outcomes
,
Dynamic stability
2021
Purpose
The volume of medial meniscus (MM) extrusion at 10° and 90° knee flexions using three-dimensional (3D) magnetic resonance imaging (MRI) and assessed relevant clinical outcomes at 1-year follow-up were evaluated.
Methods
Twenty-four patients who underwent MM posterior root repair were retrospectively reviewed. At 10° and 90° knee flexions, the meniscal extrusion distance and volume were measured using 3D meniscus models constructed by SYNAPSE VINCENT®. The correlation between Knee Injury and Osteoarthritis Outcome Score, Lysholm, International Knee Documentation Committee scores, Tegner activity, and pain visual analog scales and changes in MM extrusion were assessed.
Results
No significant differences in the MM medial extrusion were observed between 10° and 90° knee flexions postoperatively. MM posterior extrusion (MMPE) decreased significantly at 10° and 90° knee flexions postoperatively. At 90° knee flexion, the meniscus volume at the intra-tibial surface increased at 3 and 12 months postoperatively. The MM extrusion volume increased slightly at 10° knee flexion; however, the volume decreased significantly at 90° knee flexion postoperatively. The change in MMPE significantly correlated with clinical scores. All 12-month clinical scores were significantly improved compared to preoperative scores.
Conclusions
The progression of meniscus posterior extrusion and reduction of its volume at 90° knee flexion can be suppressed by MM posterior root repair. Postoperative clinical scores correlated with reductions of the posterior extrusion. Regarding clinical relevance, the dynamic stability of the meniscus can be maintained by MM posterior root repair, which is an effective therapeutic method for improving its clinical status.
Level of evidence
Level IV.
Journal Article
Accurate placement of a tibial tunnel significantly improves meniscal healing and clinical outcomes at 1 year after medial meniscus posterior root repair
by
Yuki Okazaki
,
Yuya Kodama
,
Keisuke Kintaka
in
Aged
,
Arthroplasty, Replacement, Knee
,
Arthroscopy
2021
Purpose
A medial meniscus posterior root tear results in the loss of meniscal circumferential hoop stress and causes a pathological posteromedial extrusion of the medial meniscus. Although creating a tibial tunnel in the anatomic place improves postoperative medial meniscus posterior extrusion, no studies have evaluated the relationship between tibial tunnel position and clinical outcomes. This study aimed to evaluate how tibial tunnel positioning of medial meniscus posterior root pullout repair affects meniscal healing status and clinical outcomes.
Methods
Sixty-two patients with 64 medial meniscus posterior root tears (mean age 62.8 ± 7.9 years) who had undergone pullout repairs and second-look arthroscopies were included. All 62 patients were Lachman test negative. Three-dimensional computed tomography images of the tibial surface were evaluated using a rectangular measurement grid to assess the tibial tunnel centre and medial meniscus posterior root attachment centre. Spearman’s rank correlation analysis was undertaken to determine displacement distance from the medial meniscus posterior root attachment centre to the tibial tunnel centre and a meniscal healing score, as well as clinical outcomes at 1 year post-repair.
Results
Tibial tunnel centres were located more anteriorly and medially than the medial meniscus posterior root attachment centre (mean distance 5.0 ± 2.2 mm). The mean meniscal healing score was 6.7 ± 1.8 of 10 possible points. The 1-year postoperative clinical scores showed significant improvement compared with preoperative scores for all the items. There was a significant negative correlation in the absolute distance between the medial meniscus posterior root attachment centre and the tibial tunnel centre with the meniscal healing score (
ρ
= − 0.39,
p
= 0.002). Furthermore, there were significant positive correlations between the distance between the medial meniscus posterior root attachment centre and the tibial tunnel centre in the mediolateral direction and patient-based clinical outcomes (
ρ
= 0.25–0.43,
p
< 0.05).
Conclusion
Accurate placement of a tibial tunnel, especially in the mediolateral direction, significantly improved meniscal healing and clinical outcomes at 1 year following medial meniscus posterior root repair. Surgeons should create a medial meniscus posterior root tibial tunnel at the anatomic attachment with particular attention to the mediolateral position.
Level of evidence
Level IV.
Journal Article
Occupational radiation exposure of zoo veterinarians during x-ray procedures: a real-time dosimetry study
2025
Objectives: We used real-time dosimetry for the quantitative evaluation of occupational radiation exposure among zoo veterinarians and animal keepers during x-ray procedures to identify key procedural and contextual determinants of exposure variation.Methods: This retrospective observational study analyzed 251 radiographic procedures at multiple zoological facilities in Japan. Occupational exposure was measured in real time with a semiconductor dosimeter that recorded the personal dose equivalent, Hp(10), at 1-second intervals. Procedural variables included professional role, manual restraint, sedation or anesthesia, equipment type, tube voltage (kVp), and tube current-time product (mAs). Between-group comparisons were conducted using nonparametric tests, and multiple linear regression was used to identify the independent predictors of occupational exposure.Results: The overall median Hp(10) per procedure was 0.35 (IQR: 0.15-0.99) μSv. Veterinarians received significantly higher doses than animal keepers (P = .006). Elevated Hp(10) values were associated with procedures involving large-bodied carnivores, performed without manual restraint or sedation. Multivariate analysis identified 5 significant predictors-professional role (β = −.75), manual restraint (β = −.24), tube voltage (β = .43), tube current-time product (β = .11), and large-animal group (β = .34)-explaining 60.4% of the variance (adjusted R2 = 0.604).Conclusions: Despite the overall low exposure levels, some procedures resulted in Hp(10) values exceeding 10 μSv. A combination of procedural and contextual factors influenced exposure. These findings underscore the importance of comprehensive radiation-protection strategies, including optimized workflows, appropriate use of sedation, and standardized operator protocols, in alignment with international dose-optimization principles.
Journal Article
Iron and Cancer: A Special Issue
2023
Iron is an essential element for all organisms, and iron-containing proteins play critical roles in cellular functions [...].Iron is an essential element for all organisms, and iron-containing proteins play critical roles in cellular functions [...].
Journal Article