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Yoshihiko Murakami

Publications and source records attributed to Yoshihiko Murakami.

8 recordsLinked to original sources
PubMed2007

A novel synthetic tissue-adhesive hydrogel using a crosslinkable polymeric micelle.

We prepared a novel tissue-adhesive hydrogel by using a polymeric micelle consisting of an aldehyde-terminated poly(ethylene glycol)-poly(D,L-lactide) (PEG-PLA) block polymer. A Schiff base is chemically formed between the amino groups in a polyallylamine and the aldehyde groups on the surface of polymeric micelles. The hydrogel was formed in approximately 2 s when the polymeric micelle solution and polyallylamine solution are mixed in vitro. The hydrogel was rapidly formed in vivo, and it adhered to a tissue surface. Our novel tissue-adhesive hydrogel creates no risk of infectious contaminations, because it consists of only synthetic materials. Further, PEG and PLA are known to be biocompatible and noncytotoxic. The results obtained in the present study show that a hydrogel prepared by the formation of a Schiff base between aldehyde and amine groups will potentially address the need for novel tissue-adhesive materials.

Cross-Linking Reagents↗
PubMed2006

Temporal bone histopathologic abnormalities associated with mitochondrial mutation T7511C.

OBJECTIVES: We previously reported a mitochondrial T7511C mutation in the tRNA gene in a Japanese family with nonsyndromic hearing loss (HL). However, the temporal bone histopathology associated with T7511C has not been reported. The aim of the present study is to report histopathologic findings of a temporal bone from a patient in the Japanese family with this mutation. STUDY DESIGN: Single case study. METHODS: A temporal bone was obtained from the right ear of a male subject with progressive HL from 5 years of age and who died at 60 years of age from cerebral infarction. The bone was embedded, sectioned, and stained with hematoxylin-eosin for light microscopic study. Graphic reconstruction of the cochlea was performed using the method described by Schuknecht to determine loss of the stria vascularis and neurosensory elements including hair cells and spiral ganglion neurons. RESULTS: The most significant histopathologic finding was severe loss of spiral ganglion cells in all turns of the cochlea. Severe loss of neuronal filaments in Rosenthal's canal was also observed. The organ of Corti showed scattered loss of inner and outer hair cells in the basal turn. Partial atrophy of the stria vascularis was observed in all turns of the cochlea. CONCLUSION: Our results suggest that severe loss of spiral ganglion cells was the main cause of sensorineural HL associated with the T7511C mutation.

Atrophy↗
PubMed2005

[Temporal bone histopathology in a patient suspected of inner ear extension of otitis media].

We report the histopathological findings in the temporal bone of a 30-year-old female who died of cervical esophageal carcinoma. The temporal bone sections revealed severe bilateral suppurative labyrinthitis and otitis media that presumably occurred immediately before her death. Many inflammatory cells were present in the middle ear, particularly around the stapes and the round window niche. They had also infiltrated the inner ear via the annular ligament of the stapes and the round window membrane. Inflammatory cell accumulation was also observed in the peri- and endolymphatic spaces, and it was most severe in the basal turn. Most of the inner and outer hair cells were preserved, but some had degenerated or were missing. Numerous round cells were observed in the modiolus, and some of the spiral ganglion cells had degenerated. On the basis of these findings, we concluded that bacterial otitis media had extended in to the inner ear via the oval window and round window membrane and had resulted in suppurative labyrinthitis. These findings are consistent with those of stage II suppurative labyrinthitis according to the classification of Schuknecht.

Adult↗
PubMed2004

[Temporal bone histopathology exhibiting cochleosaccular degeneration in a patient with profound deafness].

We herein report the histopathological findings of the temporal bone taken from a patient with unilateral profound deafness since early childhood. The patient was a 72-year-old male who died of lung cancer and extensive metastases including the tongue. The patient had a history of profound hearing loss in his left ear since childhood. The histopathological finding of the left temporal bone revealed a severe atrophy of the organ of Corti, a detached and rolled-up tectorial membrane, a moderate loss of the stria vascularis, and a severe loss of spiral ganglion cells. In addition, the macula of the saccule was severely degenerated. The marked degeneration in the inner ear indicated a cochleosaccular disorder, which is a typical temporal bone finding in cases of viral labyrinthitis and hereditary hearing impairment. The present patient was suspected to have suffered cochleosaccular degeneration as a result of an inner ear viral infection during childhood because the number of spiral ganglion cells was significantly reduced because of secondary neural degeneration.

Aged↗
PubMed2003

Acoustic trauma.

Explore the source record for details and available documents.

Aged↗
PubMed2003

Novel gene assay by probe-regulated simultaneous separation using capillary electrophoresis (CE-PRESS).

A novel methodology, a probe-regulated simultaneous separation using capillary electrophoresis (CE-PRESS), was developed for simultaneous assay of multiple genes. The single-stranded (ss) DNA-polymer conjugate-probes were placed in a capillary, and then a mixture of target ssDNAs was injected. These ssDNAs were hybridized with corresponding complementary ssDNA-polymer conjugate-probes after charging the capillary. Two resulting double-stranded (ds) complexes of ssDNAs and ssDNA-polymer conjugate-probes were detected at different migration times. We found that the electrophoretic mobilities of two ssDNA-poly(acrylamide) conjugate-probes [-(5'-GCCACCAGC-3')m-AAm(n)- and -(5'-ACCTTCACT-3')p-AAm(q)-; AAm, acrylamide] obtained by copolymerizing 5'-methacryloyl-modified ssDNA and AAm were different, depending on their molar fraction of ssDNA, although the ssDNAs chain lengths were the same. Two ssDNAs (5'-GCTGGTGGC-3' and 5'-AGTGAAGGT-3') having the same chain length were successfully separated with our novel system, although the separation of these ssDNAs is impossible in conventional capillary electrophoresis systems.

Journal Article↗
PubMedDate not supplied

DNA-responsive hydrogels that can shrink or swell.

Molecule-responsive hydrogels are reputed to be smart materials because of their unique properties. We recently reported that hydrogels containing directly grafted single-stranded (ss) DNA or ssDNA-polyacrylamide conjugate in a semi-interpenetrating network (semi-IPN) manner that "only shrunk" by the addition of ssDNA samples. To date, however, no DNA-responsive hydrogels have been reported capable of "swelling" in response to specific DNAs. Smart materials capable of both shrinking and swelling in response to specific DNAs would be very useful in biochemical and biomedical applications. Here, we show a novel "shrinking or swelling" DNA-responsive mechanism. Novel hybrid hydrogels containing rationally designed ssDNA as the cross-linker were capable of shrinking or swelling in response to ssDNA samples and recognizing a single base difference in the samples. On the basis of the results presented in this paper, it is envisioned that these novel hybrid hydrogels could function and have potential in applications such as DNA-sensing devices and DNA-triggered actuators.

Acrylic Resins↗