Evaluation of Antibiotic Penicillin G Activities Based on Electrochemical Measurement of a Tetrazolium Salt.

This study focused on the electrochemical properties of tetrazolium salts to develop a simple method for evaluating viable bacterial counts, which are indicators of drug susceptibility. Considering that the oxidized form of tetrazolium, which has excellent cell membrane permeability, changes to the insoluble reduced form formazan inside the cell, the number of viable cells was estimated based on the reduction current of the tetrazolium remaining in the bacterial suspension. Dissolved oxygen is an important component of bacterial activity. However, it interferes with the electrochemical response of tetrazolium. We estimated the number of viable bacteria in the suspension based on potential-selective current responses that were not affected by dissolved oxygen. Based on solubility, cell membrane permeability, and characteristic electrochemical properties of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium, we developed a method for rapidly measuring viable bacteria within one-fifth of the time required by conventional colorimetric methods for drug susceptibility testing.

Evaluation of Bacterial Activity Based on the Electrochemical Properties of Tetrazolium Salts.

This study focused on the electrochemical properties of tetrazolium salts to develop a simple method for evaluating viable bacterial counts, which are indicators of hygiene control at food and pharmaceutical manufacturing sites. Given that the oxidized form of 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which has excellent cell membrane permeability, changes to the insoluble reduced form of formazan inside the cell, the number of viable cells was estimated by focusing on the reduction current of MTT remaining in the suspension. Dissolved oxygen is an important substance for bacterial activity; however, it interferes with the electrochemical response of MTT. We investigated the electrochemical properties of MTT to obtain a potential-selective current response that was not affected by dissolved oxygen. Real-time observation of viable bacteria in suspension revealed that uptake of MTT into bacteria was completed within 10 min, including the lag period. In addition, we observed that the current response depends on viable cell density regardless of the bacterial species present. Our method enables a rapid estimation of the number of viable bacteria, making it possible to confirm the safety of food products before they are shipped from the factory and thereby prevent food poisoning.

Successful Application of Stereotactic Body Radiation Therapy for Ventricular Tachycardia Substrate in a Patient With Nonischemic Cardiomyopathy.

Cardiac stereotactic body radiotherapy (SBRT) has been gaining attention as a potential treatment for patients with ventricular tachycardia (VT). Here, we describe a nonischemic patient with severe heart failure and VTs originating from the deep anteroseptal substrate that was refractory to standard and bipolar catheter ablations, and was successfully managed with SBRT. In conclusion, anteroseptal VTs resistant to catheter ablation in severe nonischemic heart failure might be an indication for cardiac SBRT as palliative therapy.

One-pot multi-step transformation of D-allose from D-fructose using a co-immobilized biocatalytic system.

In this report, Shinella zoogloeoides NN6 was discovered to produce two rare sugar producing enzymes, D-allulose 3-epimerase (DAE) and L-rhamnose isomerase (LRhI), when cultured with L-rhamnose as the sole carbon source. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of purified DAE and LRhI revealed that the molecular masses of the monomeric subunits are 37 and 43 kDa, respectively, whereas gel filtration analysis showed that purified DAE and LRhI are 148 and 162 kDa, respectively, indicating that both enzymes form tetramers. The activity of DAE was the highest at 80°C in acetate buffer (pH 6.5) with Co2+, whereas LRhI exhibited maximum activity at 60°C in glycine-NaOH buffer (pH 9.0) with Mn2+. A co-immobilized biocatalyst was constructed using DAE (3.2 U) and LRhI (40 U). Activity profile analysis of this co-immobilized biocatalyst revealed that DAE activity was highest at 80°C in acetate buffer (pH 5.5), whereas the highest activity for LRhI was observed at 55°C in sodium phosphate buffer (pH 7.0). D-Allose was produced from 2% (w/w) D-fructose via D-allulose at 60°C and pH 9.0 in a one-pot reaction, providing a mixture of D-glucose, D-fructose, D-allulose and D-allose at a ratio of 1.3:62.7:23.6:12.4. This is the first report describing one-pot D-allose production using LRhI and DAE expressed in a single microorganism.

Development of highly sensitive optical nanoantenna for bacterial detection.

Gold nanoparticles (AuNPs) are chemically stable and serve as excellent labels because their characteristic red coloration based on the localized surface plasmon resonance (LSPR) does not fade. However, it is necessary to control the structure of AuNPs to use them as labels for various analyses, because their optical properties depend strongly on their size, shape, and state of aggregation. In this study, we developed gold nanostructures (AuNSs) by encapsulating many small AuNPs within a polymer for scattering light-based bacterial detection. The AuNSs consisting of many small nanoparticles provided stronger scattered light intensity than a single AuNP of the same particle size. We found that the aggregation of the AuNSs enhanced the scattering light intensity, depending strongly on their aggregation states, and did not affect the wavelength of the scattering light observed under a dark-field microscope. By specifically binding the antibody-introduced AuNSs to the antigen on the bacterial surface, it was possible to label the target bacteria and detect them based on their light scattering characteristics. In addition, to improve the accuracy of the selective identification of the cells of interest, labels based on scattered light should ideally have a fixed wavelength of scattered light with high intensity. From these perspectives, we developed a method of constructing an optical antenna on the surface of target bacterial cells using antibody-introduced NSs.

Influence of PD-L1 expression in immune cells on the response to radiation therapy in patients with oropharyngeal squamous cell carcinoma.

BACKGROUND AND PURPOSE: To investigate influences of proteins involved with tumor immunity on outcomes of radiotherapy for oropharyngeal squamous cell carcinoma (OPSCC). MATERIAL AND METHODS: We performed immunohistochemical staining to examine expressions of p16 and proteins involved with tumor immunity in 92 OPSCC patients treated with radiotherapy. RESULTS: Patients with abundant infiltrating CD8-positive cells had the significantly better overall survival (OS) rate than patients with fewer CD8-positive cells (p = 0.026). Patients with higher PD-L1 expression in tumor cells (TC 1-3) had a better outcome than those with low PD-L1 expression in tumor cells (TC 0) for both OS (p = 0.019) and progression-free survival (PFS) rate (p = 0.032). Patients with high PD-L1 expression in infiltrating immune cells (IC 3) showed significantly better OS (p = 0.009) and PFS (p = 0.011) than those with low PD-L1 expression (IC 0-2). Patients with p16-negative and IC 3 showed similar OS to patients with p16-positive and IC 0-2. P16-positive tumors had a significantly higher CD8-positive cell infiltration and PD-L1 expression in tumor cells than p16-negative tumors. CONCLUSIONS: In addition to tumor p16 expression, PD-L1 expression in TC and IC can be useful for predicting the response of OPSCC to radiotherapy.

Cutaneous-type adult T-cell leukemia/lymphoma presenting as a solitary large skin nodule: a review of the literature.

Adult T-cell leukemia/lymphoma (ATLL) often involves the skin. Cases with skin lesions without either leukemic nor lymph node involvement have been categorized into a cutaneous type. While the clinical manifestations of the cutaneous-type ATLL are variable, including multiple papules, nodules, plaques, or erythroderma, a solitary skin nodule alone is rare, and only 2 cases have been reported in the literature. We present a 58-year-old Japanese patient with cutaneous-type ATLL that presented as a large, solitary skin nodule as the sole clinical feature. The skin tumor was completely resolved after treatment with x-ray and electron beam irradiation.

Analyses of dose-response in radiotherapy for patients with mature T/NK-cell lymphomas according to the WHO classification.

BACKGROUND AND PURPOSE: This study was conducted to analyze the influence of radiotherapy doses and chemotherapy doses and clinical parameters on in-field disease control in order to assess the optimal radiation doses for treatment of mature T/NK-cell lymphomas according to the newly proposed WHO classification. PATIENTS AND METHODS: Subjects consisted of 62 patients with mature T/NK-cell lymphomas treated with radiotherapy at four Japanese institutions between 1983 and 2002. We reevaluated all histopathological specimens of non-Hodgkin's lymphomas (NHL), using the WHO classification. Radiation therapy was usually delivered to the involved field. The majority of patients also received adriamycin-based chemotherapy such as CHOP, modified CHOP, or more intensive chemotherapy. RESULTS: There were no significant differences in radiosensitivity among subtypes of mature T/NK-cell lymphomas, at least between extranodal NK/T-cell lymphomas, nasal type and peripheral T-cell lymphomas, unspecified. There was a radiation dose-response in non-bulky mature T/NK-cell lymphomas, indicating that radiation doses of more than 52 Gy may be required to obtain in-field control. However, it was difficult to obtain local control of bulky T-cell lymphomas, even with high doses of irradiation. CONCLUSIONS: Mature T/NK-cell lymphomas were more radioresistant than B-cell lymphomas such as diffuse large B-cell lymphomas (DLBCL). The chemotherapy including adriamycin did not improve the in-field control of mature T/NK-cell lymphomas. These results were obtained by using non-randomized data and the significance of these results is limited by bias in data. However, our results suggest that the treatment strategy which is usually used for DLBCL, that is, a combined modality of CHOP and around 40 Gy of radiotherapy, may not be sufficiently effective for mature T/NK-cell lymphomas.