Efficient Sensor Node Selection for Observability Gramian Optimization.

Optimization approaches that determine sensitive sensor nodes in a large-scale, linear time-invariant, and discrete-time dynamical system are examined under the assumption of independent and identically distributed measurement noise. This study offers two novel selection algorithms, namely an approximate convex relaxation method with the Newton method and a gradient greedy method, and confirms the performance of the selection methods, including a convex relaxation method with semidefinite programming (SDP) and a pure greedy optimization method proposed in the previous studies. The matrix determinant of the observability Gramian was employed for the evaluations of the sensor subsets, while its gradient and Hessian were derived for the proposed methods. In the demonstration using numerical and real-world examples, the proposed approximate greedy method showed superiority in the run time when the sensor numbers were roughly the same as the dimensions of the latent system. The relaxation method with SDP is confirmed to be the most reasonable approach for a system with randomly generated matrices of higher dimensions. However, the degradation of the optimization results was also confirmed in the case of real-world datasets, while the pure greedy selection obtained the most stable optimization results.

Evaluation of the depiction ability of similar subtraction images using digital chest radiographs of different patients.

The temporal subtraction (TS) technique requires the same patient's chest radiographs (CXRs) acquired on different dates, whereas the similar subtraction (SS) technique can be used in patients who have no previous CXR, using similar CXRs from different patients. This study aimed to examine the depiction ability of SS images with simulated nodules in comparison with that of TS images with 2- and 7-year acquisition intervals. One hundred patients were randomly selected from our image database. The most recently acquired images of the patients were used as target images for subtraction. The simulated nodule was superimposed on each target image to examine the usefulness of the SS technique. The most (Top 1) and ten most (Top 10) similar images for each target image were identified in the 24,254-image database using a template-matching technique, and used for the SS technique. SS and TS images were obtained using a previously developed nonlinear image-warping technique. The depiction ability of SS and TS images was evaluated using the contrast-to-noise ratio (CNR). The proportion of Top 1 SS images showing higher CNR than that of the TS images with 2- and 7-year acquisition intervals was 28% (28/100) and 33% (33/100), respectively. Moreover, the proportion of cases that had any of the Top 10 SS images with higher CNRs than those of TS images with 2- and 7-year acquisition intervals was 56% (56/100) and 72% (72/100), respectively. Our study indicates that the SS technique can potentially be used to detect lung nodules on CXRs.

Quantitative Photodeprotection Assessment of Caged Resveratrol by Fluorescence Measurement.

For monitoring the regenerated bioactivity of a masked bioactive compound, resveratrol (a luciferase inhibitor) was selected to target such a compound. Caged resveratrol, masked by thiochromone-type photolabile-protecting groups was synthesized in the study. Each caged resveratrol showed lower bioactivity when compared to that shown by the original molecule. After photoirradiation, the original bioactivity was found to be regenerated. Furthermore, the fluorescent compound derived from the thiochromone-type photolabile-protecting groups was generated simultaneously. A linear correlation was observed between the regenerated bioactivity and generated fluorescence intensity. Thus, we quantitatively monitored the recovered bioactivity successfully by measuring the fluorescence.

Intracellular trafficking of bio-nanocapsule-liposome complex: Identification of fusogenic activity in the pre-S1 region of hepatitis B virus surface antigen L protein.

Bio-nanocapsules (BNCs) are a hollow nanoparticle consisting of about 100-nm liposome (LP) embedding about 110 molecules of hepatitis B virus (HBV) surface antigen (HBsAg) L protein as a transmembrane protein. Owing to the human hepatocyte-recognizing domains on the N-terminal region (pre-S1 region), BNCs have recently been shown to attach and enter into human hepatic cells using the early infection mechanism of HBV. Since BNCs could form a complex with an LP containing various drugs and genes, BNC-LP complexes have been used as a human hepatic cell-specific drug and gene-delivery system in vitro and in vivo. However, the role of BNCs in cell entry and intracellular trafficking of payloads in BNC-LP complexes has not been fully elucidated. In this study, we demonstrate that low pH-dependent fusogenic activity resides in the N-terminal part of pre-S1 region (NPLGFFPDHQLDPAFG), of which the first FF residues are essential for the activity, and which facilitates membrane fusion between LPs in vitro. Moreover, BNC-LP complexes can bind human hepatic cells specifically, enter into the cells via clathrin-mediated endocytosis, and release their payloads mostly into the cytoplasm. Taken together, the BNC portion of BNC-LP complexes can induce membrane fusion between LPs and endosomal membranes under low pH conditions, and thereby facilitate the endosomal escape of payloads. Furthermore, the fusogenic domain of the pre-S1 region of HBsAg L protein may play a pivotal role in the intracellular trafficking of not only BNC-LP complexes but also of HBV.

[Patient with massive hemothorax due to blunt trauma saved by transcatheter arterial embolization (TAE)].

A 78-year-old man who fell from a step ladder was transported to our hospital by ambulance under the diagnosis of multiple rib fractures and right hemothorax. Since he was in shock on arrival, endotracheal intubation and tube thoracotomy were immediately performed. Though 2 liters of blood was evacuated, persistent hemorrhage was observed, requiring continuous rapid infusion and blood transfusion. Emergency thoracic arteriography revealed active bleeding from a branch of the right internal thoracic artery. Transcatheter arterial embolization (TAE) was performed using vascular embolization coils and porous gelatin particles. These procedures successfully controlled active hemorrhage from the chest. Intrathoracic hematoma was evacuated through the 2nd large chest tube. Chest tubes were removed on the 7th day. He was discharged on the 17th day without any complications.

Computerized image-searching method for finding correct patients for misfiled chest radiographs in a PACS server by use of biological fingerprints.

We have developed an automated image-searching method based on biological fingerprints for identifying correct patients in misfiled chest radiographs in a picture archiving and communication system (PACS) server. We used five biological fingerprints including distinctive anatomic structures in a misfiled chest radiograph of an unknown patient to find another image of the same patient stored with correct patient information in a PACS server. The correlation values were determined for the corresponding biological fingerprints in all images in the image server. The correlation indices as a measure of the overall similarity of the two images were determined from the summation of five correlation values and the combination of correlation values with the weighting factors. Finally, the correct patient was identified automatically by the image with the highest correlation index. By use of the summation of five correlation values as the correlation index, 78.0% (156/200) of the 200 patients for misfiled images were correctly identified in the database. When we applied the weighting factors for each biological fingerprint to determine the correlation index, the performance in identifying the correct patient was improved to 87.5% (175/200). An additional 5.0% (10/200) of images were included in the Top 10 ranking of the correlation index in the database. These cases could be identified manually by radiology personnel. We conclude that the automated image-searching method based on biological fingerprints with weighting factors would be useful for identification of the correct patient in the case of misfiled chest radiographs in a PACS server.

Data management solution for large-volume computed tomography in an existing picture archiving and communication system (PACS).

Multidetector row computed tomography (MDCT) creates massive amounts of data, which can overload a picture archiving and communication system (PACS). To solve this problem, we designed a new data storage and image interpretation system in an existing PACS. Two MDCT image datasets, a thick- and a thin-section dataset, and a single-detector CT thick-section dataset were reconstructed. The thin-section dataset was archived in existing PACS disk space reserved for temporary storage, and the system overwrote the source data to preserve available disk space. The thick-section datasets were archived permanently. Multiplanar reformation (MPR) images were reconstructed from the stored thin-section datasets on the PACS workstation. In regular interpretations by eight radiologists during the same week, the volume of images and the times taken for interpretation of thick-section images with (246 CT examinations) or without (170 CT examinations) thin-section images were recorded, and the diagnostic usefulness of the thin-section images was evaluated. Thin-section datasets and MPR images were used in 79% and 18% of cases, respectively. The radiologists' assessments of this system were useful, though the volume of images and times taken to archive, retrieve, and interpret thick-section images together with thin-section images were significantly greater than the times taken without thin-section images. The limitations were compensated for by the usefulness of thin-section images. This data storage and image interpretation system improves the storage and availability of the thin-section datasets of MDCT and can prevent overloading problems in an existing PACS for the moment.

Clinical usefulness of temporal subtraction method in screening digital chest radiography with a mobile computed radiography system.

The temporal subtraction image which is obtained by subtraction of a previous image from a current image of the same patient can enhance interval changes. In this study, we applied the temporal subtraction method for lung cancer screening and evaluated the clinical usefulness by comparing the review time and the detection accuracy of lung cancers without and with subtraction images. Since 1996, we have been performing screening chest radiography for a mass survey of lung cancers in the Iwate Prefecture, Japan, by using a van equipped with a computed radiography system and a digital archive system. During the 12 years from 1997 to 2008, a total of 186,340 examinations were performed, and 121,526 (65.2%) temporal subtraction images were provided in the lung cancer screening. Twenty-four abnormal cases with lung cancer and 270 normal cases were selected from the lung cancer screening. Five radiologists participated in an observer performance study and interpreted previous and current chest radiographs without and with temporal subtraction images. In addition, radiologists interpreted previous and current images with a double-reading method. The average ROC curves demonstrated a significant improvement in the detection accuracy of lung cancers with the temporal subtraction images compared with that without the temporal subtraction images, and that with the double-reading method. Therefore, we believe strongly that the temporal subtraction method is clinically useful for radiologists in the detection of lung cancers in mass surveys.

Increased leukocyte ROCK activity in patients after acute ischemic stroke.

BACKGROUND: Rho-kinase (ROCK) is a downstream effector of Rho GTPase that is known to regulate various pathological processes important to the development of ischemic stroke, such as thrombus formation, inflammation, and vasospasm. Inhibition of ROCK leads to decreased infarct size in animal models of ischemic stroke. This study tests the hypothesis that ROCK activity increases during the acute phase of ischemic stroke. METHODS: Serial blood samples were drawn from 10 patients with acute ischemic stroke presenting within 24 h of symptom onset and with NIHSS scores >or=4. Samples were taken at 24, 48, and 72 h. Leukocyte ROCK activity was determined by immunoblotting leukocyte lysates with antibodies to the phosphorylated form of myosin-binding subunit (P-MBS) of myosin light chain phosphatase (MLCP). MBS and P-MBS contents were normalized to alpha-tubulin, and ROCK activity was expressed as the ratio of P-MBS to MBS. ROCK activities in these 10 patients were compared to baseline ROCK activities in 10 control subjects without acute illness and matched for sex, age, and number of vascular risk factors using a two-tailed Student's t-test. RESULTS: The mean NIHSS score in patients with stroke was 15.4. ROCK activity was significantly increased at 24 and 48 h in patients after acute ischemic stroke when compared to control values, with peak elevations at 48 h after stroke onset. There was no apparent correlation between ROCK activity and stroke severity based on NIHSS. CONCLUSIONS: Leukocyte ROCK activity is increased in patients after acute ischemic stroke with maximal activity occurring about 48 h after stroke onset. These findings suggest that activation of ROCK may play a role in the pathogenesis of ischemic stroke in humans.

A computer-assisted system for diagnostic workstations: automated bone labeling for CT images.

Although accurate information on thoracolumbar bone structure is essential when computed tomography (CT) images are examined, there is no automated method of labeling all the vertebrae and ribs on a CT scan. We are developing a computer-aided diagnosis system that labels ribs and thoracolumbar vertebrae automatically and have evaluated its accuracy. A candidate bone was extracted from the CT image volume data by pixel thresholding and connectivity analysis. All non-bony anatomical structures were removed using a linear discriminate of distribution of CT values and anatomical characteristics. The vertebrae were separated from the ribs on the basis of their distances from the centers of the vertebral bodies. Finally, the thoracic cage and lumbar vertebrae were extracted, and each vertebra was labeled with its own anatomical number by histogram analysis along the craniocaudal midline. The ribs were labeled in a similar manner, based on location data. Twenty-three cases were used for accuracy comparison between our method and the radiologist's. The automated labeling of the thoracolumbar vertebrae was concordant with the judgments of the radiologist in all cases, and all but the first and second ribs were labeled correctly. These two ribs were frequently misidentified, presumably because of pericostal anatomical clutter or high densities of contrast material in the injected veins. We are confident that this system can contribute usefully as part of a picture archiving and communication system workstation, though further technical improvement is required for identification of the upper ribs.

Demonstration of elevation and localization of Rho-kinase activity in the brain of a rat model of cerebral infarction.

Evidence that Rho-kinase is involved in cerebral infarction has accumulated. However, it is uncertain whether Rho-kinase is activated in the brain parenchyma in cerebral infarction. To answer this question, we measured Rho-kinase activity in the brain in a rat cerebral infarction model. Sodium laurate was injected into the left internal carotid artery, inducing cerebral infarction in the ipsilateral hemisphere. At 6 h after injection, increase of activating transcription factor 3 (ATF3) and c-Fos was found in the ipsilateral hemisphere, suggesting that neuronal damage occurs. At 0.5, 3, and 6 h after injection of laurate, Rho-kinase activity in extracts of the cerebral hemispheres was measured by an ELISA method. Rho-kinase activity in extracts of the ipsilateral hemisphere was significantly increased compared with that in extracts of the contralateral hemisphere at 3 and 6 h but not 0.5 h after injection of laurate. Next, localization of Rho-kinase activity was evaluated by immunohistochemical analysis in sections of cortex and hippocampus including infarct area 6 h after injection of laurate. Staining for phosphorylation of myosin-binding subunit (phospho-MBS) and myosin light chain (phospho-MLC), substrates of Rho-kinase, was elevated in neuron and blood vessel, respectively, in ipsilateral cerebral sections, compared with those in contralateral cerebral sections. These findings indicate that Rho-kinase is activated in neuronal and vascular cells in a rat cerebral infarction model, and suggest that Rho-kinase could be an important target in the treatment of cerebral infarction.

Potential usefulness of biological fingerprints in chest radiographs for automated patient recognition and identification.

RATIONALE AND OBJECTIVES: The purpose of this study was to demonstrate the potential usefulness of "biological fingerprints" in chest radiographs for automated patient recognition and identification. MATERIALS AND METHODS: Thoracic fields, cardiac shadows, the superior mediastinum, lung apices, a part of the right lung, and the right lower lung that includes the costophrenic angle were used as biological fingerprints in chest radiographs. Each of the biological fingerprints in a current chest radiograph was used as a template for determination of the correlation value with the corresponding biological fingerprint in a previous chest radiograph for patient recognition and identification. The overall performance of the method developed was examined in terms of receiver operating characteristic curves. RESULTS: Receiver operating characteristic curves obtained with different biological fingerprints, except for the part of the right lung, indicated a high performance in identifying patients. These results showed that a new concept of biological fingerprints in radiologic images would be useful in patient recognition and identification. The low performance with the part of the right lung seems to be related to a general observation that this region does not usually include features unique to a specific patient. The performance of the artificial neural networks by use of a combination of five biological fingerprints was higher than results obtained with each biological fingerprint. CONCLUSION: The use of automated patient identification based on biological fingerprints in chest radiographs is promising for helping to discover misfiled patient images, especially in a picture archiving and communication system environment.

A quantitative study of the facial nerve in mice prenatally exposed to ethanol.

Pregnant ICR mice were given 20% ethanol intraperitoneally twice on day 13 of gestation and allowed to give birth to offspring. The offspring were killed at 56 days of age and the motor root of their facial nerve was examined histologically and morphometrically. The cross-sectional area of the facial nerve of mice prenatally exposed to ethanol was significantly smaller than that of the control mice. There was no significant difference in the total number of myelinated axons or the mean axonal diameter between control and ethanol-exposed mice, but the mean diameter of myelinated fibers (axon + myelin sheath) and the thickness of myelin sheath were significantly decreased in the treated group. These results suggest that prenatal exposure to ethanol disturbs myelination of the motor root of the facial nerve and may cause permanent neurological effects.

[Evaluation of clinical usefulness of Web-based results on distribution of brain MRI].

We evaluated clinical usefulness of MD online Image Match with the clinical images of 70 intracranial lesions. Total diagnostic accuracy and image similarity between the clinical image and search results was better with enhanced-T1WI. In all sequence, localization was matched precisely in more than 90% of cases. MDOL Image Match was thought to be useful for enhancing the quality of brain MRI diagnosis.