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Biomedical subjects

Kensaku Mori

Publications and source records attributed to Kensaku Mori.

At least 19 recordsLinked to original sources
PubMed2006

A case of metastatic testicular cancer complicated by tumour lysis syndrome and choriocarcinoma syndrome.

A 26-year-old man was referred to our hospital for treatment of metastatic testicular cancer. The pathological diagnosis was choriocarcinoma with seminoma. Sequential computerized tomography examinations revealed rapidly progressing bulky liver metastases and a lung metastasis. Chemotherapy with bleomycin, etoposide and cisplatin (BEP) was started on the day of admission. Subsequently, the patient suffered from tumour lysis syndrome (TLS) and massive haemorrhage at metastatic sites. The latter complication is also called choriocarcinoma syndrome. To our knowledge, this is the first case report of testicular cancer complicated with both critical conditions. Intensive care and radiological intervention barely prevented a fatal outcome. The urological oncologist should be aware of the potential complications TLS and choriocarcinoma syndrome in cases of rapidly progressive and high-volume choriocarcinoma.

Adult↗
PubMed2006

Schnurri-2 mutant mice are hypersensitive to stress and hyperactive.

The bone morphogenetic protein (BMP)/transforming growth factor-beta (TGF-beta)/activin superfamily regulates development of the nervous system during embryogenesis and is also suggested to be involved in adult brain function. However, how BMP/TGF-beta/activin signals modulate neuronal function remains unknown. Schnurri is a transcription factor that contains two metal finger regions. Mammalian Shn-2 enters the nucleus from the cytoplasm in response to BMP-2 stimulation and plays an important role in BMP-dependent adipogenesis. To investigate whether mammalian Shn plays a role in adult brain function, we examined the behaviors of mutant mice lacking Shn-2 (Shn-2(-/-)). Shn-2(-/-) mice exhibited hypersensitivity to stress accompanied by anxiety-like behavior. Consistent with this, stress-induced corticosterone levels were significantly higher in Shn-2(-/-) mice compared to wild-type controls. Interestingly, Shn-2(-/-) mice were more active than wild-type mice in a familiar environment. The basal and stress-induced expression levels of the immediate early genes, including c-Fos, were decreased in Shn-2(-/-) mice compared to wild-type mice. Thus, Shn-2 plays a critical role in locomotion and anxiety-like behavior.

Animals↗
PubMed2006

A leucine-rich repeat membrane protein, 5T4, is expressed by a subtype of granule cells with dendritic arbors in specific strata of the mouse olfactory bulb.

Segregation of neuron-type-specific synaptic connections in different strata is a characteristic feature shared by the olfactory bulb (OB) and retina. In the mammalian OB, mitral cells form dendrodendritic synapses with granule cells (GCs) in the deep stratum of the external plexiform layer (EPL), whereas tufted cells form dendrodendritic synapses in the superficial stratum. In the search for membrane proteins with strata-specific expression patterns, we found that a leucine-rich repeat membrane protein (5T4 oncofetal trophoblast glycoprotein) was expressed selectively by a subset of superficial GCs. The somata of 5T4-positive GCs were localized in or near the mitral cell layer, and their apical dendrites ramified preferentially in the superficial stratum of the EPL, where tufted cell dendrites ramified. Strata-specific expression of 5T4 was found also in the retina: 5T4 was expressed selectively by rod-bipolar cells and a subset of amacrine cells whose dendrites ramified in a specific sublamina of the inner plexiform layer. During the perinatal and postnatal development of the OB, 5T4 expression paralleled in time the formation of dendrodendritic synapses in the EPL. Odor deprivation during the first postnatal month selectively reduced the thickness of the superficial stratum of the EPL and the number of 5T4-positive GCs. Because 5T4 is known to interact with actin cytoskeleton, these observations suggest that 5T4 is involved in the formation or maintenance of strata-specific dendritic ramification or synaptic connection of subsets of local interneurons.

Amacrine Cells↗
PubMed2006

A transcriptional enhancer that directs telencephalon-specific transgene expression in mouse brain.

Telencephalin (TLCN, intercellular adhesion molecule-5 [ICAM-5]) is a cell adhesion molecule belonging to the immunoglobulin superfamily, which plays important roles in dendritic morphogenesis and synaptic plasticity. The expression of TLCN is restricted to neurons in the most rostral brain segment, telencephalon. Here, we examined a transcriptional regulatory mechanism underlying the telencephalon-specific expression of TLCN. TLCN gene is located in the ICAM gene cluster containing ICAM-1, ICAM-4, and TLCN (ICAM-5) within 30 kb on the mouse chromosome 9. The nucleotide sequence of the 5'-flanking region of mouse TLCN gene is highly homologous to that of human and dog orthologs, suggesting the presence of important regulatory elements for its transcription. To determine the telencephalon-specific enhancer region, we generated several lines of transgenic mice that harbor transgenes consisting of different length of the 5'-flanking region of mouse TLCN gene (3.9, 1.5, 1.1, and 0.2 kb) fused to humanized renilla green fluorescent protein cDNA as a fluorescent reporter. Consequently, we identified a crucial region between 1.1 and 0.2 kb upstream of the transcription start site that directs the telencephalon-specific expression. This enhancer was applied to the Cre/loxP-mediated conditional expression system to generate several transgenic lines with different patterns of recombination in the telencephalon and will be further used as a powerful tool for genetic manipulation in the telencephalic neurons.

5' Flanking Region↗
PubMed2006

Telencephalin slows spine maturation.

Dendritic filopodia are highly dynamic structures, and morphological maturation from dendritic filopodia to spines is intimately associated with the stabilization and strengthening of synapses during development. Here, we report that telencephalin (TLCN), a cell adhesion molecule belonging to the Ig superfamily, is a negative regulator of spine maturation. Using cultured hippocampal neurons, we examined detailed localization and functions of TLCN in spine development and synaptogenesis. At early stages of synaptogenesis, TLCN immunoreactivity gradually increased and was present in dendritic shafts and filopodia. At later stages, TLCN tended to be excluded from mature spine synapses in which PSD-95 (postsynaptic density-95) clusters were apposed to presynaptic synaptophysin clusters. To elucidate the function of TLCN in spine maturation, we analyzed the dendrite morphology of TLCN-overexpressing and TLCN-deficient neurons. Overexpression of TLCN caused a dramatic increase in the density of dendritic filopodia and a concomitant decrease in the density of spines. Conversely, TLCN-deficient mice showed a decreased density of filopodia and an acceleration of spine maturation in vitro as well as in vivo. These results demonstrate that TLCN normally slows spine maturation by promoting the filopodia formation and negatively regulating the filopodia-to-spine transition. In addition, we found that spine heads of mature neurons were wider in TLCN-deficient mice compared with wild-type mice. Thus, the preservation of immature synapses by TLCN may be an essential step for refinement of functional neural circuits in the telencephalon, that take charge of higher brain functions such as learning, memory, and emotion.

Animals↗
PubMed2006

Detection of hepatic metastases using ferucarbotran-enhanced MR imaging: feasibility and diagnostic accuracy of three-dimensional sensitivity-encoding water-excitation multishot echo-planar sequence (3D-SWEEP).

PURPOSE: To evaluate the diagnostic accuracy of a ferucarbotran-enhanced three-dimensional sensitivity-encoding water-excitation multishot echo-planar sequence (3D-SWEEP) for detecting hepatic metastases compared to a T2*-weighted fast field-echo (FFE) sequence. MATERIALS AND METHODS: Twenty-five consecutive patients with hepatic metastases underwent ferucarbotran-enhanced MRI on a 1.5-T unit before hepatic resections. Eighty-two foci of metastases were confirmed by histopathology or intraoperative ultrasonography (US). Signal-intensity decay (SID), tumor-to-liver contrast (TLC), and image quality were compared between T2*-weighted FFE and 3D-SWEEP. Three independent observers reviewed three imaging sets: set 1, without 3D-SWEEP or T2*-weighted FFE; set 2, with T2*-weighted FFE; and set 3, with 3D-SWEEP. The mean values of areas under alternative free response receiver operating characteristic curves (Az) and sensitivities were compared among the three sets. RESULTS: SID and TLC were significantly greater for 3D-SWEEP than T2*-weighted FFE, although 3D-SWEEP had poorer image quality. The mean Az and sensitivity were significantly greater for set 3 compared to set 1 for detecting overall lesions, and compared to sets 1 and 2 for detecting lesions of 1-2 cm in diameter. CONCLUSION: Despite relatively prominent artifacts, ferucarbotran-enhanced 3D-SWEEP was more sensitive and accurate than T2*-weighted FFE for detecting hepatic metastases.

Aged↗
PubMed2006

Trends in oncological CT imaging: clinical application of multidetector-row CT and 3D-CT imaging.

Computed tomography (CT) plays an essential role in oncological imaging as the modality of screening for malignancies, mapping out the treatment strategy at staging, assessing response to the treatment, and following up patient outcome after the treatment. The advent of multidetector-row CT (MDCT) has brought about dramatic changes in clinical oncological imaging. The very superior temporal and spatial resolution of MDCT has transformed CT imaging from a transaxial cross-sectional technique into an isotropic volume-imaging technique. MDCT facilitates multiphasic contrast-enhanced study for a wide range of body scanning in a single examination, as well as providing flexibility of multidirectional reconstruction and high-quality three-dimensional imaging. With increases in the number of detector rows year by year, systems with 64-detector rows have become commercially available in 2006. The purpose of this article is to review the status of CT imaging in oncological imaging: (1) to outline the impact of MDCT, focusing on oncological imaging and (2) to review the clinical applications of oncological CT imaging with MDCT.

Humans↗
PubMed2006

Evaluation of a prostate biopsy strategy for cancer detection using a computer simulation system with virtual needle biopsy for three-dimensional prostate models.

AIM: We evaluated a prostate biopsy strategy for cancer detection using a computer simulation system with virtual needle biopsy for three-dimensional (3D) prostate models. METHODS: Two 3D prostate models with a volume of 25 cc or 50 cc were constructed from computed tomographic images of radical prostatectomy specimens. The peripheral zone (PZ) and transition zone (TZ) were arranged in the prostate models according to the anatomical information. Four thousand patterns of cancer lesions were automatically inserted into each prostate model with a proportion of 75% in PZ and 25% in TZ. Average hit rates (AHR) in prostate models were evaluated both with an increased number of biopsy cores and various angles of virtual needle biopsy. The influence of adding secondary tumors for hit rates was also evaluated. RESULTS: For both sizes, the laterally angled biopsy in 4-8 core biopsy schemes showed higher AHR than the vertical plane biopsy, while the vertical plane biopsy in 10-18 core biopsy schemes showed higher AHR than the laterally angled biopsy. A higher number of biopsy cores increased the AHR of secondary tumors. CONCLUSIONS: Our results suggest that it is important in prostate cancer detection to change the needle placement according to the number of biopsy cores and the size of the prostate.

Biopsy, Needle↗
PubMed2006

Maps of odorant molecular features in the Mammalian olfactory bulb.

The olfactory bulb (OB) is the first relay station of the central olfactory system in the mammalian brain and contains a few thousand glomeruli on its surface. Because individual glomeruli represent a single odorant receptor, the glomerular sheet of the OB forms odorant receptor maps. This review summarizes the emerging view of the spatial organization of the odorant receptor maps. Recent studies suggest that individual odorant receptors are molecular-feature detecting units, and so are individual glomeruli in the OB. How are the molecular-feature detecting units spatially arranged in the glomerular sheet? To characterize the molecular-feature specificity of an individual glomerulus, it is necessary to determine the molecular receptive range (MRR) of the glomerulus and to compare the molecular structure of odorants within the MRR. Studies of the MRR mapping show that 1) individual glomeruli typically respond to a range of odorants that share a specific combination of molecular features, 2) each glomerulus appears to be unique in its MRR property, and 3) glomeruli with similar MRR properties gather together in proximity and form molecular-feature clusters. The molecular-feature clusters are located at stereotypical positions in the OB and might be part of the neural representation of basic odor quality. Detailed studies suggest that the glomerular sheet represents the characteristic molecular features in a systematic, gradual, and multidimensional fashion. The molecular-feature maps provide a basis for understanding how the olfactory cortex reads the odor maps of the OB.

Animals↗
PubMed2006

A method for bronchoscope tracking by combining a position sensor and image registration.

This paper describes a method for tracking a bronchoscope by combining a position sensor and image registration. A bronchoscopy guidance system is a tool for providing real-time navigation information acquired from pre-operative CT images to a physician during a bronchoscopic examination. In this system, one of the fundamental functions is tracking a bronchoscope's camera motion. Recently, a very small electromagnetic position sensor has become available. It is possible to insert this sensor into a bronchoscope's working channel to obtain the bronchoscope's camera motion. However, the accuracy of its output is inadequate for bronchoscope tracking. The proposed combination of the sensor and image registration between real and virtual bronchoscopic images derived from CT images is quite useful for improving tracking accuracy. Furthermore, this combination has enabled us to achieve a real-time bronchoscope guidance system. We performed evaluation experiments for the proposed method using a rubber phantom model. The experimental results showed that the proposed system allowed the bronchoscope's camera motion to be tracked at 2.5 frames per second.

Artificial Intelligence↗
PubMed2005

Critical period for sensory experience-dependent survival of newly generated granule cells in the adult mouse olfactory bulb.

Granule cells in the olfactory bulb (OB) are continually produced and added into the neuronal circuit in the adult brain. Sensory input to the OB plays a key role in the survival of newly generated granule cells. Here, we examined in the adult mice whether there is a time window after the generation of new granule cells when their survival is strongly influenced by sensory input. New granule cells were labeled by BrdUrd injection, and the mice were deprived of sensory input unilaterally by naris cauterization. During the initial 14 days after BrdUrd labeling, the number of BrdUrd-positive granule cells was similar for deprived and undeprived OBs. At 28 days or later, the BrdUrd-positive cell number remarkably decreased in the deprived OB. Cauterization at days 14-28 effectively reduced the number of BrdUrd-positive granule cells, whereas 2-week cauterization before or after this period produced little effect. Administration of diazepam, a GABAA receptor modulator, decreased the number of BrdUrd-positive granule cells. The diazepam administration was most effective at days 14-28. Histochemical examination showed that activation of caspase-3 was accompanied by apoptotic cell death of granule cells that was induced by sensory deprivation or diazepam administration. Double labeling with activated caspase-3 and BrdUrd indicated that granule cells at days 14-20 were most susceptible to cell death. These results indicate that there is a critical period when the survival of new granule cells is determined in a sensory experience-dependent manner and that the pharmacological manipulation can mimic the effect of sensory deprivation.

Animals↗
PubMed2005

State-dependent sensory gating in olfactory cortex.

Sensory systems show behavioral state-dependent gating of information flow that largely depends on the thalamus. Here we examined whether the state-dependent gating occurs in the central olfactory pathway that lacks a thalamic relay. In urethane-anesthetized rats, neocortical EEG showed a periodical alternation between two states: a slow-wave state (SWS) characterized by large and slow waves and a fast-wave state (FWS) characterized by faster waves. Single-unit recordings from olfactory cortex neurons showed robust spike responses to adequate odorants during FWS, whereas they showed only weak responses during SWS. The state-dependent change in odorant-evoked responses was observed in a majority of olfactory cortex neurons, but in only a small percentage of olfactory bulb neurons. These findings demonstrate a powerful state-dependent gating of odor information in the olfactory cortex that works in synchrony with the gating of other sensory systems. They suggest a state-dependent switchover of signal processing modes in the olfactory cortex.

Animals↗
PubMed2005

A novel phenylalanine-based targeting signal directs telencephalin to neuronal dendrites.

Neurons sort out a variety of functional molecules to appropriate subcellular destinations. Telencephalin (TLCN; intercellular adhesion molecule-5) is a cell adhesion molecule specifically localized to somatodendritic membranes in the telencephalic neurons. Here, we established a new in vivo strategy to analyze neuronal sorting mechanisms by ectopic expression of molecules of interest in the cerebellar Purkinje cells of transgenic mice. By using this system, we identified a novel dendritic targeting determinant in the cytoplasmic tail region of TLCN. A full-length TLCN ectopically expressed in the Purkinje cells was localized exclusively to dendrites but not to axons. In contrast, a deletion of cytoplasmic C-terminal 12 amino acids (residues 901-912) or a point mutation of Phe905 to Ala abrogated the dendrite-specific targeting with appearance of the truncated and point-mutated TLCN in both axons and dendrites. Furthermore, an addition of the C-terminal 17 amino acids (residues 896-912) of TLCN to an unrelated molecule (CD8) was sufficient for its specific targeting to dendrites in several types of neurons. Because the C-terminal region of TLCN does not contain any canonical dendritic targeting sequences such as the tyrosine-based motif or the dileucine motif, this study suggests a novel mechanism of protein trafficking to the dendritic compartment of neurons.

Amino Acid Motifs↗
PubMed2005

Development of a navigation-based CAD system for colon.

We propose a navigation-based computer aided diagnosis (CAD) system for the colon. When diagnosing the colon using virtual colonoscopy (VC), a physician makes a diagnosis by navigating (flying-through) the colon. However, the viewpoints and the viewing directions must be changed many times because the colon is a very long and winding organ with many folds. This is a time-consuming task for physicians. We propose a new navigation-based CAD system for the colon providing virtual unfolded (VU) views, which enables physicians to observe a large area of the colonic wall at a glance. This system generates VU, VC, and CT slice views that are perfectly synchronized. Polyp candidates, which are detected automatically, are overlaid on them. We applied the system to abdominal CT images. The experimental results showed that the system effectively generates VU views for observing colon regions.

Algorithms↗
PubMed2005

Automated nomenclature of bronchial branches extracted from CT images and its application to biopsy path planning in virtual bronchoscopy.

We propose a novel anatomical labeling algorithm for bronchial branches extracted from CT images. This method utilizes multiple branching models for anatomical labeling. In the actual labeling process, the method selects the best candidate models at each branching point. Also a special labeling procedure is proposed for the right upper lobe. As an application of the automated nomenclature of bronchial branches, we utilized anatomical labeling results for assisting biopsy planning. When a user inputs a target point around suspicious regions on the display of a virtual bronchoscopy (VB) system, the path to the desired position is displayed as a sequence of anatomical names of branches. We applied the proposed method to 25 cases of CT images. The labeling accuracy was about 90%. Also the paths to desired positions were generated by using anatomical names in VB.

Algorithms↗
PubMed2005

Hybrid bronchoscope tracking using a magnetic tracking sensor and image registration.

In this paper, we propose a hybrid method for tracking a bronchoscope that uses a combination of magnetic sensor tracking and image registration. The position of a magnetic sensor placed in the working channel of the bronchoscope is provided by a magnetic tracking system. Because of respiratory motion, the magnetic sensor provides only the approximate position and orientation of the bronchoscope in the coordinate system of a CT image acquired before the examination. The sensor position and orientation is used as the starting point for an intensity-based registration between real bronchoscopic video images and virtual bronchoscopic images generated from the CT image. The output transformation of the image registration process is the position and orientation of the bronchoscope in the CT image. We tested the proposed method using a bronchial phantom model. Virtual breathing motion was generated to simulate respiratory motion. The proposed hybrid method successfully tracked the bronchoscope at a rate of approximately 1 Hz.

Algorithms↗
PubMed2005

Three-dimensional computed tomographic images of pelvic muscle in anorectal malformations.

PURPOSE: The anatomy of the pelvic flower muscles based on investigation of gross section slides of a specimen does not always correspond with those described by Pena. Therefore, we restudied the anatomy with 3-dimensional (3D) images of the pelvic muscle produced with computed tomography. METHODS: Thirty-eight patients with anorectal malformations before anorectoplasty were investigated with a multi-detector row helical computed tomography (MRH-CT). Images of the pelvic part were obtained with a slice thickness of 1 mm and a reconstruction pitch of 0.5 mm. A 3D reconstruction was made with the volume rendering method. Lateral views of the 3D CT reconstructed images of the pelvic muscle were compared with the same views of the type corresponding to Pena's schematic drawings in the literature. RESULTS: Study of the 3D reconstructions demonstrated that the pelvic muscles of each type were less uniform than the ones described by Pena. There was a great difference even in the same type of anatomy. The differences between the 3D image and the description by Pena were most notable in the high type and particularly in the description of the vertical fibers and the parasagittal muscles. CONCLUSIONS: A 3D image with MRH-CT can provide useful preoperative information about the anatomy of the pelvic flower muscles in each case.

Abnormalities, Multiple↗