Real-time assay for exosome membrane fusion with an artificial lipid membrane based on enhancement of gramicidin A channel conductance.

We report that the channel activities of gramicidin A in a supported lipid bilayer (SLB) were modulated by membrane fusion with exosomes. The mechanism of the modulation was an increase in the number of exosomes inserting into the SLB membrane, rather than enhancements of the single channel activity of gramicidin A. The modulation of apparent channel activities was applicable to the exosome fusion assay. This assay revealed that the membrane fusion of HEK-293 and MCF-7 exosomes was enhanced at pH 6.0, and the initial rates of membrane fusion for MCF-7 exosomes were higher than those for HEK-293 cells.

A Planar Bilayer Lipid Membrane Sensor Using a Miniaturized Auto-patch System.

A bilayer lipid membrane sensor was constructed with a miniaturized auto-patch system. The performance of the patch system was optimized to obtain an analytically relevant signal. A biosensor based on an anti-BSA-antibody as a receptor and gramicidin as a signal transduction element was demonstrated. The sensor for BSA exhibited a detection limit of pg/mL level for BSA.

Comparison of Geriatric Nutritional Risk Index scores on physical performance among elderly patients with chronic obstructive pulmonary disease.

OBJECTIVES: The Geriatric Nutritional Risk Index (GNRI) is a new prognostic indicator for nutritional status-related complications and mortality among the elderly. Here we aimed to compare 6-min walk distance (6MWD) between high and low GNRI groups for patients with COPD. METHODS: We enrolled 63 elderly men with COPD. These subjects were divided into two groups based on their GNRI scores: high GNRI group (≥92 points; n = 44) and low GNRI group (n = 19); we compared 6MWD between these groups. RESULTS: The subjects' characteristics between the high and the low GNRI groups were similar, except for BMI and serum albumin levels. 6MWD were significantly lower in the low GNRI group (279.5 ± 112.3 m versus 211.1 ± 125.3 m; p = 0.03). CONCLUSIONS: The GNRI has a more close relation with exercise tolerance and may be a useful nutritional assessment scale for elderly patients with COPD.

Effect of terfenadine and pentamidine on the HERG channel and its intracellular trafficking: combined analysis with automated voltage clamp and confocal microscopy.

The effects of terfenadine and pentamidine on the human ether-a-go-go related gene (hERG) channel current and its intracellular trafficking were evaluated. Green fluorescent protein (GFP)-linked hERG channels were expressed in HEK293 cells, and the membrane current was measured by an automated whole cell voltage clamp system. To evaluate drug effects on channel trafficking to the cell membrane, the fraction of channel present on the cell membrane was quantified by current measurement after drug washout and confocal microscopy. Terfenadine directly blocked the hERG channel current but had no effect on trafficking of hERG channels to the cell membrane after application in culture medium for 2 d. In contrast, pentamidine had no direct effect on the hERG channel current but reduced trafficking of hERG channels. The two drugs inhibited hERG channel function through different mechanisms: terfenadine through direct channel blockade and pentamidine through inhibition of channel trafficking to the cell membrane. Combined use of automated voltage clamp and confocal microscopic analyses would provide insights into the mechanisms of drug-induced QT-prolongation and arrhythmogenesis.

Planar lipid bilayers containing gramicidin A as a molecular sensing system based on an integrated current.

The channel activity of gramicidin A in free-standing planar lipid bilayers with different charges of polar head groups and various lengths of hydrocarbon tails were analyzed in terms of the channel conductance, the lifetime of channel events and the magnitude of integrated currents. The channel activity of gramicidin A in lipid bilayers is tunable by adjusting the membrane composition. The in situ coupling of the anti-BSA antibody as a model protein to the amine moiety of phosphatidylethanolamine (PE) in a lipid bilayer by the amine coupling method allowed us to design an antigen (BSA)-sensitive interface, in which the integrated current, rather than the frequency of channel event, can be used as an analytical signal. The potential of the present system for highly sensitive and selective detection of BSA at 10(-9) g/mL level is demonstrated.

[Studies on digital watermark embedding intensity against image processing and image deterioration].

In order to apply digital watermarking to medical imaging, it is required to find a trade-off between strength of watermark embedding and deterioration of image quality. In this study, watermarks were embedded in 4 types of modality images to determine the correlation among the watermarking strength, robustness against image processing, and image deterioration due to embedding. The results demonstrated that watermarks which were embedded by the least significant bit insertion method became unable to be detected and recognized on image processing even if the watermarks were embedded with such strength that could cause image deterioration. On the other hand, watermarks embedded by the Discrete Cosine Transform were clearly detected and recognized even after image processing regardless of the embedding strength. The maximum level of embedding strength that will not affect diagnosis differed depending on the type of modality. It is expected that embedding the patient information together with the facility information as watermarks will help maintain the patient information, prevent mix-ups of the images, and identify the test performing facilities. The concurrent use of watermarking less resistant to image processing makes it possible to detect whether any image processing has been performed or not.