Publications by authors named "Kohei Muto"

6 Publications

  • Page 1 of 1

A novel COL4A1 variant associated with recurrent epistaxis and glioblastoma.

Hum Genome Var 2021 May 14;8(1):18. Epub 2021 May 14.

Department of Neurology, Tokushima University Graduate School of Biomedical Sciences, Tokushima, Japan.

COL4A1-related disorders are characterized by a higher incidence of cerebral hemorrhage than other hereditary cerebral small vessel diseases. Accumulating data have shown broad phenotypic variations, and extracerebral hemorrhages have been linked to these disorders. Moreover, the coexistence of neural tumors has been described. Here, we report a Japanese family with a novel COL4A1 variant, including a patient with recurrent epistaxis and glioblastoma.
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http://dx.doi.org/10.1038/s41439-021-00150-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8121905PMC
May 2021

Memory B cell resurgence requires repeated rituximab in myasthenia gravis.

Neuromuscul Disord 2017 Oct 21;27(10):918-922. Epub 2017 Jun 21.

Department of Clinical Neuroscience, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan.

The immunologic effects of rituximab (RTX) in myasthenia gravis (MG) remain to be explored. We aimed to clarify immunologic reactions and their association with response to RTX in MG. Regulatory T cell and B cell profiles of MG patients were monitored. Two patients presenting with generalized MG with anti-acetylcholine receptor antibodies were treated with RTX. The treatment led to sustained clinical improvement, discontinuation of intravenous immunoglobulin or plasma exchange, and reduction of prednisolone and other drugs. One patient was in remission for more than one year, whereas the other patient exhibited deterioration of symptoms within one year. Disease activity was associated with the repopulation of IgDCD27 and IgDCD27 memory B cells. Clinicians should be aware of the possibility that MG ranges in the duration of B cell depletion and additional RTX should be prescribed upon resurgence of memory B cells.
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http://dx.doi.org/10.1016/j.nmd.2017.06.012DOI Listing
October 2017

Ultrastructure and motility of the spermatozoa of Polypedates leucomystax (Amphibia, Anura, Rhacophoridae).

Cytoskeleton (Hoboken) 2013 Mar 26;70(3):121-33. Epub 2012 Nov 26.

Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.

Sperm morphology is thought to be shaped by evolutionary pressure from the fertilization environment. Rhacophoridae (Amphibia, Anura) include both foam-nesting and nonfoam-nesting species and exhibit a variety of sperm morphologies. Here, we examine the sperm morphology and motility of a foam-nesting Rhacophoridae frog, Polypedates leucomystax. Their spermatozoa have a sickle-shaped head and a thick tail containing two axonemes with their doublet microtubule ones (Db1s) facing one another. These two axonemes are surrounded by hundreds of satellite microtubules that form a hexagonal lattice structure. The spermatozoa move spirally by directly converting their tail movements into propulsion force, similar to the movement of the sickle-shaped spermatozoa of Xenopus laevis. By comparing the spermatozoa of P. leucomystax to those of other foam-nesting Rhacophoridae frogs, Rhacophorus and Chiromantis, and to the nonfoam-nesting Rhacophoridae frog, Buergeria buergeri, we found the following: (i) Spermatozoa of foam-nesting Rhacophoridae share common morphological features, a pair of axonemes and crystallized satellite microtubules. (ii) Spermatozoa of nonfoam-nesting Rhacophoridae do not exhibit these features. (iii) Sperm motility in foam-nesting Rhacophoridae is adapted to viscous environments. (iv) A diversity of sperm morphology and motility exists even among foam-nesting Rhacophoridae frogs. (v) The spermatozoa of Rhacophorus are more adapted to the foam nest than the spermatozoa of Polypedates.
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http://dx.doi.org/10.1002/cm.21092DOI Listing
March 2013

Quantitative determination of colored oily soil adhering to metal surface using digital image data.

J Oleo Sci 2011 ;60(10):505-13

Graduate School of Environment and Information Sciences, Yokohama National University, Japan.

A method for calculating the amount of colored soil on a flat metal surface from digital image data was examined. Round samples cut out of SUS tape were soiled with oily soil mixed with sudan III, placed in sample bottles, and washed using a tube rotator. Images of the samples before and after the washing process were captured using a CCD camera and the image data were processed by a computer. The shine from the metallic surface was controlled by using indirect lighting. It was necessary to diminish the effect of the substrate's color, and to this end, we attempted to apply linear and non-linear color correction procedures. We found that the use of gamma correction after linear correction to remove the effect of the metal surface color was the most accurate quantitative method. Additionally, we conducted a washing test with commercial detergents using this quantitative method for image data and found that the removal process for the greasy soil from the metal surface could be expressed as a first-order reaction.
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http://dx.doi.org/10.5650/jos.60.505DOI Listing
June 2012

Ultrastructural analysis of spermiogenesis in Rhacophorus arboreus (Amphibia, Anura, Rhacophoridae).

J Morphol 2011 Dec 20;272(12):1422-34. Epub 2011 Jul 20.

Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 6068502, Japan.

The spermatozoa of the Japanese green tree frog, Rhacophorus arboreus (Amphibia, Anura, Rhacophoridae), have a characteristic corkscrew-shaped head and a thick tail that extends perpendicular to the longitudinal axis of the head. We examined the process of spermatogenesis in Rh. arboreus, particularly spermiogenesis, using light and transmission electron microscopy. Spermiogenesis was categorized into the early, mid, and late stages based on the spermatid morphology and their location within the cyst. Early spermatids had a round nucleus and two independent flagella that elongated from a pair of parallel centrioles. The centrioles became embedded in centriolar adjunct material and attached to the nucleus. Then, the flagella were covered with a mantle-like cytoplasm that contained many microtubules. An acrosome appeared on the pointed side of the slightly elongated nucleus. Mid spermatids had an elongated rod-like head. As the nucleus elongated, the chromatin fibers became thicker and were arranged parallel to the elongation axis. An elongated acrosome was attached helically along the lateral side of the elongated nucleus. The biflagellate spermatids transformed into monoflagellate spermatids with two axonemes through a process in which the plasma membrane of each flagellum expanded. Late spermatids had a coiled or corkscrew-shaped head. An acrosome was located on the inside of the coiled cone composed of a nucleus. Parallel microtubules were connected in rows, and then became crystallized in the tail. The present report contains the first morphological description of spermatogenesis in Rhacophorus and suggests that spermiogenesis evolved to adapt to the fertilization environment.
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http://dx.doi.org/10.1002/jmor.10994DOI Listing
December 2011

A novel mechanism of sperm motility in a viscous environment: corkscrew-shaped spermatozoa cruise by spinning.

Cell Motil Cytoskeleton 2009 May;66(5):281-91

Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan.

Fertilization of the green tree frog, Rhacophorus arboreus, occurs in the viscous environment of a foam nest, which is laid on vegetation. Their spermatozoa have a characteristic corkscrew-shaped head and a thick tail that extends perpendicularly to its longitudinal axis. However, it is unclear how these corkscrew-shaped spermatozoa move in this highly viscous environment. Here, we found that the spinning of the corkscrew-shaped head, caused by winding and unwinding of the tail, enables the spermatozoa to move through the highly viscous environment of a foam nest, like a corkscrew rotating into a cork. We suggested that dislocations observed in the matrix of satellite microtubules surrounding two axonemes, reflected the planes of sliding of the axonemes, and dyneins on doublets two and six of each axoneme were active during winding and unwinding, respectively. These results provide a novel mechanism for sperm movement that is adapted specifically to a viscous fertilization environment.
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http://dx.doi.org/10.1002/cm.20358DOI Listing
May 2009