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Kaori Yamamoto

Publications and source records attributed to Kaori Yamamoto.

15 recordsLinked to original sources
PubMed2006

Conformation of amyloid fibrils of beta2-microglobulin probed by tryptophan mutagenesis.

Beta2-microglobulin (beta2-m), a protein responsible for dialysis-related amyloidosis, adopts an immunoglobulin domain fold in its native state. Although beta2-m has Trp residues at positions 60 and 95, both are located near the surface of the domain. Hence, beta2-m does not have a conserved Trp common to other immunoglobulin domains, which is buried in close proximity to the disulfide bond. To study the structure of amyloid fibrils in relation to their native fold, we prepared a series of Trp mutants. Trp60 and Trp95 were both replaced with Phe, and a single Trp was introduced at various positions. Among various mutants, W39-beta2-m, in which a Trp was introduced at the position corresponding to the conserved Trp, exhibited a remarkable quenching of fluorescence in the native state, as observed for other immunoglobulin domains. An x-ray structural analysis revealed that W39-beta2-m assumes the native fold with Trp39 located in the vicinity of the disulfide bond. Comparison of the fluorescence spectra of various mutants for the native and fibrillar forms indicated that, while the Trp residues introduced in the middle of the beta2-m sequence tend to be buried in the fibrils, those located in the C-terminal region are more exposed. In addition, the fluorescence spectra of fibrils prepared at pH 2.5 and 7.0 revealed a large difference in the fluorescence intensity for W60-beta2-m, implying a major structural difference between them.

Amino Acid Sequence↗
PubMed2006

Incomplete emptying and urinary retention in multiple-system atrophy: when does it occur and how do we manage it?

Neurogenic urinary retention can be a major cause of morbidity in multiple-system atrophy (MSA). However, the timing of its appearance has not been entirely clear, and neither have the medical and surgical modalities for managing patients. We present the data obtained from our uroneurological assessment and therapeutic interventions at various stages of MSA. We recruited 245 patients with probable MSA. We measured postvoid residuals (PVR) and performed EMG cystometry in all patients. The grand average volume of PVR was 140 mL (range, 0-760) in our patients. The average PVR volume was 71 mL in the first year, increasing to 129 mL in the second year and 170 mL by the fifth year. The percentages of patients with complete urinary retention, acontractile detrusor, and detrusor-sphincter dyssynergia (DSD) also increased. The increase in PVR resulted in a decrease in functional bladder capacity, together with an increase in detrusor overactivity and neurogenic sphincter EMG. Clean intermittent self-catheterization (CISC) was introduced in most patients. Bladder-oriented therapy (cholinergic agents) had a limited value, whereas urethra-oriented therapy benefited patients with DSD (surgery) for up to 2 years, but syncope occurred in a subset of patients (alpha-blockers). MSA patients present with large PVR by the second year of illness, and that large PVR secondarily causes urinary frequency. CISC is the recommended treatment for most patients. Urethra-oriented medication and surgery benefit patients who would have difficulty performing CISC, although careful consideration of the short-term efficacy and potential adverse effects of these alternatives is mandatory.

Adrenergic alpha-Antagonists↗
PubMed2006

Bladder sensation in peripheral nerve lesions.

OBJECTIVE: To present bladder sensory data of three common peripheral nerve lesions (e.g., distal, intermediate/focal, and proximal). METHODS: We measured first sensation (FS) and bladder capacity (BC) (not exceeding 600 ml) in 71 patients with peripheral nerve lesions: 35 diabetic neuropathy (D group), 6 post-pelvic surgery (S), and 27 cauda equina syndrome due to lumbar spondylosis (L). We excluded those with detrusor overactivity or low compliance that might affect bladder sensation. RESULTS: The mean FS was 301.7 ml (D), 271.3 ml (S), and 189.4 ml (L), with the largest being in the D group (P < 0.05); the mean BC was 495.2, 475.4, and 391.4 ml, with the largest being in the D group (P < 0.05); who commonly had less frequent toileting. The mean post-void residual volume was 106.5, 29.0, and 42.0 ml; the values tended to increase along with BC. In the D group, the mean FS in patients with skin hypoalgesia as detected by pin prick and in those without it was 407.8 and 210.0 ml. The percentage of patients with FS < 100 ml was 5.7%, 0%, and 7.4%, respectively, who commonly had urinary urgency and frequency. CONCLUSIONS: Bladder sensation is affected in diabetic neuropathy more severely than in intermediate/proximal lesions, together with somatic sensory disturbance. Bladder sensory disturbance leads to less frequent toileting, resulting in bladder over-distension and large post-void residuals. A small proportion of patients with peripheral nerve lesions develop urinary urgency, presumably reflecting irritation of the afferent nerve fibers or the urothelium.

Aged↗
PubMed2006

Urinary dysfunction and autonomic control in amyloid neuropathy.

Uro-neurological assessment was performed in four patients with small-fiber neuropathy due to amyloidosis (2 transthyretin-type/2 immunoglobulin light-chain-type). Voiding difficulties were due to detrusor weakness and impaired bladder sensation. In two patients cholinesterase inhibition treatment caused urge incontinence, indicating detrusor denervation supersensitivity. The underlying mechanisms of urinary dysfunction seem to involve postganglionic cholinergic and afferent somatic nerves.

Aged↗
PubMed2006

Establishment and characterization of a cell line, MCO-Y4, derived from canine mammary gland osteosarcoma.

A cell line, MCO-Y4, was established from a mammary gland osteosarcoma of a 16-year-old female mongrel dog. Histopathologically the tumor was composed of osteoblastic cells with an osteoid meshwork and chondroid matrix. The mean doubling time of the cells at the 93rd passage was 32.39+/-4.66 hr. Immunohistochemically, the osteoblastic and chondroblastic cells were positive for bone morphogenetic protein (BMP)-2/4 and BMP receptor (BMPR) II. The cultured cells were spindle in shape during the growth and the confluent phases. No tumor matrix was detected in the culture dish by alcian blue staining or von-Kossa silver impregnation. MCO-Y4 cells on the chamber slides showed intense immunoreactivity for BMP-2/4 and BMPR II. Noggin, an antagonist for BMP-2/4, showed the growth inhibition on MCO-Y4 cells. In addition, fibronectin might be potential for stimulating growth of MCO-Y4 cells. When transplanted into severe combined immunodeficiency mice, the cells formed tumors consisting of solid proliferation of osteoblastic and fibroblastic cells with woven-bone trabeculae. These tumor cells were intensely positive for BMP-2/4 and BMPR II. Our results suggested that the cell line might be useful for studying the role of BMPs in canine osteosarcoma and the mechanism of ossification.

Animals↗
PubMed2006

[A case of Prader-Willi syndrome treated by vitrectomy].

BACKGROUND: We report a successful treatment by vitrectomy in an adult case of Prader-Willi syndrome. CASE REPORT: We encountered a case of Prader-Willi syndrome in a 29-year-old male patient with proliferative diabetic retinopathy and cataract. We performed a vitrectomy and a cataract extraction on the patient. Initial examination showed proliferative diabetic retinopathy in both eyes. Funduscopy revealed tractional retinal detachment with atrophic retina in the right eye and retinal detachment in the inferior half of the fundus with vitreous hemorrhage in the left eye. We performed a vitrectomy with a combination of phacoemulsification and intraocular lens implantation only on the left eye. Visual acuity in the left eye increased from counting fingers preoperatively to 0.6(n.c) postoperatively. The right eye was left untreated because the visual prognosis was not expected to improve even if the eye received surgical intervention. The final visual acuity in the right eye was no light perception at the end of the follow-up period. CONCLUSION: Careful follow-up and early treatment are necessary for patients with diabetic retinopathy accompanied by Prader-Willi syndrome as it could develop into blindness.

Adult↗
PubMed2005

Aquaporin 7 deficiency is associated with development of obesity through activation of adipose glycerol kinase.

In adipocytes, hydrolysis of triglycerides results in the release of free fatty acids and glycerol. Aquaporin 7 (AQP7), a member of aquaglyceroporins, is known to permeabilize glycerol and water. We recently generated Aqp7-knockout (KO) mice and demonstrated that such mice have low plasma glycerol levels and impaired glycerol release in response to beta3-adrenergic agonist, suggesting that AQP7 acts as a glycerol gateway molecule in adipocytes for the efficient release of glycerol in vivo. Although there was no difference in body weight between WT and KO mice until 10 weeks of age, here we found that KO mice developed adult-onset obesity. The body weight and fat mass increased significantly in KO mice compared with WT mice after 12 weeks of age. Adipocytes of KO mice were large and exhibited accumulation of triglycerides compared with WT mice. The KO mice developed obesity and insulin resistance even at a young age after consumption of high-fat/high-sucrose diet. We demonstrated the enhanced glycerol kinase enzymatic activity in Aqp7-KO and -knockdown adipocytes. A series of our results indicate that AQP7 disruption elevates adipose glycerol kinase activity, accelerates triglycerides synthesis in adipocytes, and, finally, develops obesity.

3T3-L1 Cells↗
PubMed2005

Synthesis of poly(epsilon-lysine)-grafted dextrans and their pH- and thermosensitive hydrogelation with cyclodextrins.

To give pH sensitivity to a thermoreversible supramolecular-structured hydrogel system, poly(epsilon-lysine) (PL), as a cationic polymer, was grafted to dextran and used for inclusion complexation with alpha-cyclodextrins (alpha-CDs). The synthesized graft copolymer was characterized by 1H NMR spectroscopy, and the hydrogel formation was confirmed by X-ray diffraction and solid-state 13C NMR analysis. The hydrogelation was induced from a phase-separated structure of hydrated dextrans and hydrophobically aggregated inclusion complexes in buffer solution at pH 10.0. The prepared hydrogels showed thermoreversible gel-sol transitions as well as pH-sensitive phase transitions, which were recorded by the changes in UV/Vis transmittance. A rapid phase transition from gel to sol was observed upon decreasing the pH value to 4.0, which resulted from the dissociation process between the protonated guest polymer and alpha-CDs. The stimuli-responsive physical properties of the hydrogels were improved by modulating the degree of substitution of the grafted PL and the combination with alpha-CDs.

Journal Article↗
PubMed2005

[With-time change of hemodynamics in fMRI: linearity consideration after stimulation ends from stimulation beginning].

The BOLD signal responses that occur after a few seconds at the beginning and the end of stimulus are due to hemodynamic delay. A temporary increase of deoxyhemoglobin just after the beginning of stimulus causes an initial dip in the hemodynamic signal (response). After the initial dip, an increase of BOLD signal causes an overshoot. After the overshoot, a decrease of the BOLD signal due to the end of stimulus causes an undershoot. Many reports have examined the period of stimulus, but only a few have described the period after stimulus. This paper reports on a peak between the overshoot and undershoot. After the end of stimulus, the signal does not simply decrease, but shows a peak after some delay. An activated map showed the same tendency as the hemodynamics signal. This peak was termed hemodynamic over-saturation (HOS). Time control in chronological order is important to obtain a hemodynamic change in chronological order and a large, significant difference between the task and rest signal. The entire hemodynamic signal was evaluated by controlling the timing of the scan using an external trigger and by indicating the beginning of the task (rest) period using sound. The timing of the external trigger and sound are built into the sequence design as a program. From the results of the hemodynamic signal, the causal relationship between this signal and the fluctuation in oxyhemoglobin and deoxyhemoglobin can be considered.

Adult↗
PubMed2005

Floratheasaponins A-C, acylated oleanane-type triterpene oligoglycosides with anti-hyperlipidemic activities from flowers of the tea plant (Camellia sinensis).

The methanolic extract and its n-butanol-soluble fraction from the flowers of the tea plant (Camellia sinensis) were found to suppress serum triglyceride elevation in olive oil-treated mice. From the n-butanol-soluble fraction, three new acylated oleanane-type triterpene oligoglycosides, floratheasaponins A-C (1-3), were isolated together with several flavonol glycosides and catechins. The structures of 1-3 were elucidated on the basis of chemical and physicochemical evidence as 21-O-angeloyl-22-O-acetyltheasapogenol B 3-O-[beta-D-galactopyranosyl(1-->2)][beta-D-xylopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1-->3)]-beta-D-glucopyranosiduronic acid, 21,22-di-O-angeloyl-R1-barrigenol 3-O-[beta-D-galactopyranosyl(1-->2)][beta-D-xylopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1-->3)]-beta-D-glucopyranosiduronic acid, and 21-O-angeloyl-22-O-2-methylbutyryl-R1-barrigenol 3-O-[beta-D-galactopyranosyl(1-->2)][beta-D-xylopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1-->3)]-beta-D-glucopyranosiduronic acid, respectively. Floratheasaponins (1-3) showed inhibitory effects on serum triglyceride elevation, with their activities being more potent than those of theasaponins E1 (4) and E2 (5) obtained previously from the seeds of C. sinensis.

Animals↗
PubMed2004

Direct measurement of the thermodynamic parameters of amyloid formation by isothermal titration calorimetry.

Amyloid fibril deposition is associated with over 20 degenerative diseases, including Alzheimer's, Parkinson's, and prion diseases. Although research over the last few years has revealed the morphology and structural features of the amyloid form, knowledge about the thermodynamics of amyloid formation is limited. Here, we report for the first time a direct thermodynamic study of amyloid formation using isothermal titration calorimetry. Beta(2)-microglobulin, a protein responsible for dialysis-related amyloidosis, was used for extending amyloid fibrils in a seed-controlled reaction in the cell of the calorimeter. We investigated the enthalpy and heat capacity changes of the reaction, where the monomeric, acid-denatured molecules adopt an ordered, cross-beta-sheet structure in the rigid amyloid fibrils. Despite the dramatic difference in morphology, beta(2)-microglobulin exhibited a similar heat capacity change upon amyloid formation to that of the folding to the native globular state, whereas the enthalpy change of the reaction proved to be markedly lower. In comparison with the native state, the results outline the important structural features of the amyloid fibrils: a similar extent of surface burial even with the supramolecular architecture of amyloid fibrils, a lower level of internal packing, and the possible presence of unfavorable side chain contributions.

Amyloid↗
PubMed2004

[Evaluation of time resolution of the primary motor cortex by a single paradigm using a stimulation system].

Many researchers are investigating brain function by using a block paradigm in fMRI measurement. However, time resolution has been limited because the block paradigm employed data collection by consecutive image acquisition after stimulation began. Because of this problem, the evaluation of early brain activity was not adequate. Therefore, a system that was able to take imaging from a high time dependence to stimulation in real time was necessary to evaluate early brain activity. It is necessary to obtain controlled image taking by an MRI device with an external trigger by creating a sequence design in the system controlling stimulation and a sequence designed to achieve the above. The execution of a single paradigm by the originally designed sequence thus becomes possible, and arbitrarily setting all processes from stimulation to image taking is possible. It is thought that the practical use of the single paradigm designed by the control system of stimulation enables real-time imaging for stimulation and provides time-dependent data. From this, evaluation of brain activity of the primary motor cortex is possible in the early stage by event-related data collection. In addition, "sank," a relative decrement in PO(2) was also an initial stage of BOLD, that is, an initial dip occurs as a transitory signal change by using a single paradigm that synchronizes with the control system of stimulation for the evaluation of early brain activity. Moreover, it is thought that taking images by a single paradigm that is synchronized with the control system of stimulation is indispensable for time and spatial elucidation of detailed brain activity, to evaluate hyper brain function. Therefore, the brain activity in the primary visual cortex at the early stage was clarified in this study by using a single paradigm designed to synchronize with the control system of stimulation by single-shot EPI.

Adult↗
PubMed2003

Nitrogen-containing bisphosphonates induce S-phase cell cycle arrest and apoptosis of myeloma cells by activating MAPK pathway and inhibiting mevalonate pathway.

Bisphosphonates have been used for the treatment of hypercalcemia associated with malignancies and osteoporosis. It was previously reported that the mevalonate pathway is involved in nitrogen-containing bisphosphonate-induced apoptosis in osteoclasts and myeloma cells. The aim of this study was to determine the effects of two bisphosphonates, incadronate, and newly developed bisphosphonate YM529 on human myeloma cells, U266, RPMI-8226, and HS-Sultan. Both incadronate and YM529 induced S-phase cell cycle arrest and apoptosis in these myeloma cells. Treatment of the myeloma cells with cell-permeable substrates for mevalonate pathways, geranylgeraniol, and farnesol prevented bisphosphonate-mediated growth suppression. Checkpoint kinases, Chk1/2, and MAPK became phosphorylated after stimulation with bisphosphonates in the myeloma cells. Bisphosphonate-induced apoptosis was partially prevented by the pretreatment with MAPK inhibitor. These results demonstrate that incadronate and YM529 suppress the proliferation of myeloma cells through mevalonate pathway and MAPK pathway.

Apoptosis↗
PubMed2002

Sex identification of Japanese black bear, Ursus thibetanus japonicus, by PCR based on amelogenin gene.

A method for sex identification of the Japanese black bear was examined using a polymerase chain reaction (PCR) and sequencing of a part of the amelogenin gene. This gene is located on the X and Y chromosomes, and there are 54 nucleotide deletions on the Y chromosome-specific gene. Forty-seven (26 male and 21 female) DNA samples and 23 (13 male and 10 female) DNA samples, respectively extracted from white blood cells and hairs of Japanese black bears were analyzed. The primers SE47 and SE48 from this X-Y homologous region were used in sex identification by PCR amplification. These primers amplified X- and Y-specific bands, which could be used to discriminate between sexes by a length polymorphism in all samples. We suggest that PCR amplification using the primers SE47 and SE48 is useful for sex determination of the Japanese black bear and could be applied to DNA analysis of small samples such as hairs.

Amelogenin↗