Variant centromere lacking specific molecular traits in the Sykes monkey.
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Animals↗
Biomedical subjects
Y Kawamoto
Publications and source records attributed to Y Kawamoto.
PRINS analysis of the telomeric sequence in seven lemurs.
We examined the chromosomal localization of the telomeric sequence, (TTAGGG)n, in seven species of the lemurs and one greater galago, as an outgroup, using the primed in-situ labeling (PRINS) technique. As expected, the telomeric sequence was identified at both ends of all chromosomes of the eight prosimians. However, six species showed a signal at some pericentromeric regions involving constitutive heterochromatin as well. The pericentromeric region of chromosome 1 of Verreaux's sifaka (Propithecus verreauxi verreauxi) was labeled with a large and intense signal. The range of the signal considerably exceeded the area of DAPI positive heterochromatin. On the other hand, in the five lemurs, a large signal was detected also in the short arm of acrocentric chromosomes. Acquisition of the large block of the telomeric sequence into the acrocentric short arm might be interpretable in terms of the tandem growth of the heterochromatic short arm and the reciprocal translocation between heterochromatic short arms involving the telomeric sequence. Subsequently, it was postulated that meta- or submetacentric chromosomes possessing the telomeric sequence at the pericentromeric region could be formed by centric fusion between such acrocentric chromosomes.
Animals↗
Molecular mechanism of activation and superactivation of Ret tyrosine kinases by ultraviolet light irradiation.
The catalytic activities of Ret tyrosine kinases as the products of oncogene RET with multiple endocrine neoplasia type 2A (Ret-MEN2A) or 2B (Ret-MEN2B) mutations and the hybrid gene from c-RET and RFP (Rfp-Ret) were higher than those of c-Ret. We demonstrated that ultraviolet light (UV) irradiation induced activation of c-Ret and superactivation of genetically mutated, and thereby constitutively activated, Ret-MEN2A, Ret-MEN2B, and Rfp-Ret. We found that small proportions of c-Ret and Ret-MEN2B and a large proportion of MEN2A were dimerized due to disulfide bonds and that high kinase activity resided in these fractions. The UV-induced activation of c-Ret and superactivation of Ret-MEN2A and Ret-MEN2B were then shown to be closely associated with promotion of the disulfide bond-mediated dimerization of the Ret proteins. Furthermore, we showed that a large proportion of Rfp-Ret was dimerized or polymerized and that almost all kinase activities resided in the highly polymerized but not dimerized fraction. The UV-induced superactivation of Rfp-Ret was also found to be closely associated with promotion of polymerization but not with dimerization of Rfp-Ret. Further experiments revealed that UV induced intracellular dimerization and activation of the extracellular domain-deleted mutant Ret (Ret-PTC-1). Most importantly, the levels of basal kinase activity and dimerization of Ret-TPC-1-C376A, in which cysteine 376 in the tyrosine kinase domain of Ret-TPC-1 was replaced with alanine, were low and were not increased by UV irradiation. These results suggest that the cysteine at this position works as the primary target of dimerization of Ret proteins inside the cell for both the maintenance of the basal kinase activity and its promotion by UV, possibly in co-operation with the cysteine(s) in the extracellular domain of Ret-MEN2A and Rfp-Ret, which is the target of dimerization and polymerization outside the cell. The potential biological significance of the UV-mediated superactivation of mutant Ret through the newly proposed mechanism in oncogenesis is discussed.
Amino Acid Sequence↗
Chromosomal localization of 18S rDNA and telomere sequence in the aye-aye, Daubentonia madagascariensis.
Chromosomal localization of 18S rDNA and telomere sequence was attempted on the chromosomes of the aye-aye (2n = 30) using fluorescence in situ hybridization (FISH) and primed in situ labeling (PRINS), respectively. The rDNA was localized at the tip or whole of the short arm of acrocentric chromosomes 13 and 14 in all spreads observed. However, post-FISH silver-nitrate (Ag) staining showed that transcriptional activity of the rRNA genes was variable, particularly in chromosome 14, which was most frequently negative in one homologue carrying the smaller copy number of rDNA. This observation supports, at the molecular cytogenetic level, previous data concerning the relationship between the copy number of rDNA and its trancriptional activity. On the other hand, telomere sequence was localized only at the telomeric region of all chromosomes, the so-called telomere-only pattern, a characteristic similar to that of the greater bushbaby. These data may provide information on the chromosomal evolution of the lemur, because locations of rDNA and telomere sequences frequently offer important clues in reconstruction of karyotype differentiation.
Animals↗
Multivariate analysis in skull osteometry of the common tree shrew from both sides of the Isthmus of Kra in Southern Thailand.
The Isthmus of Kra in Southern Thailand consists of a lowland of about 70 km in length. It has been suggested that the Isthmus may sink beneath the sea surface according to the change of level of the sea, and may function as a zoogeographical barrier in land mammals in this region. So, the geographical variation was osteometrically examined in skull of the common tree shrew (Tupaia glis) from the both sides of Isthmus of Kra. The osteometrical examination demonstrated that the skull is larger in southern population than in northern one. In the charts of the principal component analysis, however, the morphological separation between two populations can not be obviously seen in female. While, the results of the discriminant analysis indicated the morphological separation between the two populations. These findings suggest that the zoogeographical barrier of Isthmus of Kra may have influence on the osteometrical variation in the common tree shrew, when the Isthmus was covered with sea.
Animals↗
Osteometrical skull character in the four species of tree shrew.
The skull size and shape were osteometrically examined in the four species of the tree shrews (Tupaia tana, T. javanica, T. minor and T. dorsalis). We suggest that the skull characters were affected by the species specific behavior and terrestrial, arbo-terrestrial and arboreal life, among the genus Tupaia. The neurocranium was laterally narrower in the braincase area, and the splanchnocranium was longer only on dorsal side in T. tana, and these characters were opposite to T. minor. The principal component analysis confirmed the obviously separated clusters among T. tana, T. javanica and T. minor, affected by the adaptation for each behavior. T. dorsalis was considered as terrestrial species from the results of proportion analysis and the principal component analysis.
Animals↗
Sympatric distribution of the two morphological types of the common tree shrew in Hat-Yai districts (South Thailand).
The two color types (grayish northern and reddish southern types) of the common tree shrew (Tupaia glis and Tupaia belangeri) were co-distributed in Hat-Yai region (South Thailand). Although the Isthmus of Kra in South Thailand has been considered as distribution barrier of the two types, the sympatric distribution of both types was confirmed in southern side of the Isthmus. In the principal component analysis, the skull measurement character from Hat-Yai region could also be separated into the northern and southern groups according to the skin color identification of corresponding individuals. We could generally distinguish the common tree shrew into two types by skull morphology as well as external skin color.
Animals↗
Absorption of calcium, magnesium, phosphorus, iron and zinc in growing male rats fed diets containing either phytate-free soybean protein or soybean protein isolate or casein.
The effect of dietary phytate-free soybean protein (PFS) on intestinal mineral absorption and retention was examined in growing male rats using a three-day mineral balance technique. The rats were fed diets containing PFS, soybean protein isolate (SPI) or casein at a 20% level for 5 wk. Total calcium (Ca), magnesium (Mg), phosphorus (P), iron (Fe) and zinc (Zn) contents in diets were adjusted to 0.35, 0.05, 0.7, 0.0035 and 0.003%, respectively, by supplementation of the diet with their salts. Mineral absorption and retention ratios in rats fed the PFS diet were significantly higher than those in rats fed either the SPI or casein diet. These results suggest that PFS may be a promising dietary protein source for improving the mineral bioavailability in humans.
Animals↗
[Myelopathy caused by tentorial dural arteriovenous fistula: a rare case report].
A 51-year-old man with myelopathy due to intracranial dural arteriovenous fistula (dural AVF) is reported. At age 46, the patient experienced subarachnoid hemorrhage caused by rupture of the dural AVF and underwent embolization of the lesion at another hospital. At this time, the patient complained of numbness in his legs and showed paraplegic gait disturbance. MRI scan revealed swelling of the cervical spinal cord. Cerebral angiograms demonstrated the recurrence of tentorial dural AVF fed by bilateral meningohypopheseal trunks and the right posterior inferior cerebellar artery. Arteriovenous shunt (AV shunt) flow was drained into the anterior spinal vein. It seemed that the swelling of the spinal cord and myelopathy was caused by venous hypertension of spinal veins. After surgical interruption of the right petrosal vein which connected dAVF with cerebellar veins, AV shunt was obliterated successfully. Postoperative cerebral angiograms showed disappearance of dural AVF. The patient became ambulant and his cervical spinal cord appeared normal on the postoperative MRI scan. Surgical interruption of the draining vein was simple, effective and essential treatment.
Arteriovenous Fistula↗
[Malignant peripheral nerve sheath tumor with divergent cartilage differentiation from the acoustic nerve: case report].
Malignant peripheral nerve sheath tumors(MPNSTs) of the acoustic nerve are very rare. Only seven cases of MPNST arising from the acoustic nerve have been reported. The authors present a case of MPNST with divergent cartilage and melanotic differentiation of the acoustic nerve. The patient was a 69 year old man admitted to our neurosurgical service in January 1999 complaining of left facial nerve palsy and hearing difficulty of his left ear. The initial CT showed a tumor at the left cerebellopontine angle region. On MRI the tumor was depicted as low intensity on T 1-weighted image and high intensity on T 2-weighted image, the mass was heterogeneously enhanced after administration of Gd-DTPA. The partial removal of the tumor was performed in January 1999. He was discharged February 1999. But he was admitted again because of progressive cerebellar ataxia. MRI showed the rapid regrowth of the residual tumor. In March 1999, complete removal of the tumor was performed. Histopathological analysis revealed a malignant spindle cell neoplasm with divergent cartilage and melanotic differentiation. We review the relevant literature concerning MPNST of the acoustic nerve and discuss the clinical features of malignant eighth cranial nerve tumor.
Aged↗
Immunohistochemical localization of CDK5 activator p39 in the rat brain.
We examined the immunohistochemical localization of p39, the regulatory subunit of cyclin-dependent kinase 5 (Cdk5), in the adult rat brain. Cdk5 requires either p39 or p35 to assume its active form in the mammalian CNS. We developed a specific antibody against p39, and localized p39-immunoreactivity in the rat brain. p39-immunoreactivity was observed in the neuronal somata of the cerebral cortex, hippocampus and basal ganglia, and also in the Purkinje cells. Immunopositive astrocytes and oligodendrocytes were scattered throughout the rat brain. p35 immunoactivity has been observed exclusively in neurons and was never detected in glial cells. The present results suggest that p39 and p35 may have different functional roles in the regulation of Cdk5 in the rat CNS.
Animals↗
Cellular localization of brain-derived neurotrophic factor-like immunoreactivity in adult monkey brain.
Immunohistochemical localization of brain-derived neurotrophic factor (BDNF) in the monkey brain was investigated using a polyclonal anti-BDNF antibody produced in our laboratory. The antibody recognized a single band in monkey brain homogenates, and the estimated molecular weight was approximately 14 kDa, which corresponds well to the molecular weight of BDNF monomer. BDNF-like immunoreactivity was observed in the somata and processes of discrete neuronal subpopulations in the monkey brain. BDNF-positive neurons were widely distributed in various structures of the brain, including the cerebral cortex, hippocampus, basal forebrain, basal ganglia, diencephalon, brainstem and cerebellum. In addition, immunopositive glial cells were found in some brain regions. These data suggest that BDNF may exist widely in the monkey brain, and may be concerned with various types of neurons in the monkey central nervous system.
Age Factors↗
Porous calcium phosphate coating over phosphorylated chitosan film by a biomimetic method.
A porous calcium phosphate coating deposited on chitosan films was studied using scanning electron microscopy, energy-dispersive X-ray analysis, micro-Fourier transform infrared spectroscopy (micro-FTIR) and thin-film X-ray diffractometry (XRD). Chitosan films were first prepared by dissolving chitosan powder in dilute acetic acid and drying in a flat petri dish. The films were phosphorylated using urea and H3PO4 with the P content being 0.1-0.2 wt%. Phosphorylated films soaked in saturated Ca(OH)2 solution for 8 days led to the formation of a calcium phosphate precursor phase over the entire surface. This precursor phase stimulated the growth of a porous coating of calcium-deficient hydroxy apatite when immersed in 1.5 x SBF for more than 20 days. Phosphorylated films not treated with Ca(OH)2 did not show any calcium phosphate growth upon immersion in SBF solution. The precursor phase is thought to be octacalcium phosphate, which nucleates a HAP phase during SBF treatment. Initially, this treatment in SBF results in the formation of a single-layer calcium phosphate particles over the film surface. As immersion time in SBF increases, further nucleation and growth produce a porous HAP coating. The Ca/P ratio of the HAP coating is a function of SBF immersion time.
Absorptiometry, Photon↗
Initial anchoring and proliferation of fibroblast L-929 cells on unstable surface of calcium phosphate ceramics.
Calcium phosphate ceramics constructed from beta-tricalcium phosphate (TCP) and hydroxyapatite (HAP) have been successfully used as implant materials. However, there is a possibility that these materials are responsible for an unwanted inflammatory response during wound healing. Since TCP is soluble in the body, the instability of this material may contribute to this inflammatory response. Using composite ceramics of TCP and HAP that possessed Ca/P molar ratios of 1.50, 1.55, 1.60, 1.64, and 1.67, the effect of surface instability on fibroblast L-929 cells was investigated. The time-dependent variation of the initial anchoring ratio, cell density, and cell viability were measured. In general, the cells were severely damaged and ruptured on the highly soluble thin surface layer of the TCP-HAP ceramics. The initial anchoring ratio for TCP-HAP ceramics was as high as that for the polystyrene dish (Lux, control). However, viability at 6 h decreased to less than 50% of the initial cell density on ceramics with a Ca/P molar ratio of 1.64 (20% TCP-80% HAP), while 85% of the cells were viable on Lux. The viability on 100% TCP, whose surface is the most highly soluble among the TCP-HAP ceramics used in this study, was reduced to 20%. Morphological observation showed that the anchored cells were ruptured when grown in culture medium on the 100% TCP. Although the high solubility of the thin surface layer on the TCP-HAP ceramics of the carrier was found to be the dominant factor in the decreasing cell viability, the initial viability was enhanced by the stabilization of the surface of the TCP-HAP ceramics by pre-incubating the scaffolds in a culture medium containing 10% fetal bovine serum for 3 d.
Journal Article↗
In-vitro calcium phosphate growth over functionalized cotton fibers.
Biomimetic growth of calcium phosphate compound on cotton sheets treated with tetraethoxy silane and soaked in simulated body fluid solution was studied using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), micro-Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). Micro-FTIR and EDAX results show that silicon was coupled to the cotton fiber when cotton was treated with tetra-ethoxy silane (TEOS) at 125 degrees C for 1 h. Calcium phosphate nucleation started to occur on the surface of TEOS-treated cotton fibers upon immersion in 1.5xSBF (simulated body fluid solution) within 3 days and after 20 days, all the fiber surfaces were found covered with a thick and porous coating of calcium phosphate. The Ca and P determined by inductively coupled plasma spectroscopy (ICP) analysis revealed that the Ca/P ratio as well as the amount of calcium phosphate coating depends on the soaking time in SBF solution.
Journal Article↗
Increased brain-derived neurotrophic factor-containing axons in the basal ganglia of patients with multiple system atrophy.
Brain-derived neurotrophic factor (BDNF) has a neurotrophic effect not only on mesencephalic dopaminergic neurons, but also on striatal neurons. To investigate whether the abnormal expression of BDNF occurs in the basal ganglia of patients with Parkinson disease (PD) and multiple system atrophy (MSA), we compared the BDNF levels in the striatum and globus pallidus of patients with PD or MSA to controls using immunohistochemistry. Furthermore, to quantitatively evaluate the immunohistochemical changes in the striatum, image analysis of the putamen was performed. BDNF-positive nerve fiber bundles and fine granular structures were scattered throughout the striatum and globus pallidus of all samples. Most of these granular structures were observed in glial fibrillary acidic protein-positive astrocytes. In addition, BDNF-positive neurites were abundant in the striatum of all MSA patients, and numerous BDNF-positive varicose fibers were found in the globus pallidus of some MSA cases with particularly severe striatal involvement. These observations suggest that the upregulated expression of BDNF may occur as a protective mechanism in the striatum of MSA patients, and that severe striatal degeneration may cause the aberrant accumulation of BDNF in the striatal projection areas of the globus pallidus of MSA patients.
Adult↗
Biological activity profiles of 1alpha,25-dihydroxyvitamin D2, D3, D4, D7, and 24-epi-1alpha,25-dihydroxyvitamin D2.
We have synthesized several 1alpha,25-dihydroxyvitamin D [1alpha,25(OH)2D] derivatives and evaluated their biological activity in terms of their binding affinity for the vitamin D receptor (VDR) and vitamin D-binding protein (DBP), antiproliferative or differentiation-inducing effects on human promyelocytic leukemic HL-60 cells, and transcriptional activity on a rat 25-hydroxyvitamin D3-24-hydroxylase gene promoter, including two vitamin D-responsive elements (VDREs), and human osteocalcin gene promoter, including a VDRE in transfected human osteosarcoma MG-63 cells. Furthermore, human VDR- or retinoic acid X receptor alpha (RXR alpha)-mediated luciferase activities of the derivatives were also measured by a one-hybrid system in human epitheloid carcinoma, cervix HeLa cells and African green monkey kidney CV-1 cells. Binding affinity for VDR, bone-resorbing activity, antiproliferative and cell-differentiating effects, transactivation potencies on target genes and VDR- or RXR alpha-mediated gene regulations of 1alpha,25(OH)2D2 and 1alpha,25(OH)2D4 were almost comparable to the effects of 1alpha,25(OH)2D3 while 24-epi-1alpha,25(OH)2D2 and 1alpha,25(OH)2D7 were much less active than 1alpha,25(OH)2D3 in these respects. This is the first report concerning biological assessment of 1alpha,25(OH)2D2, 1alpha,25(OH)2D3, 1alpha,25(OH)2D4, 24-epi-1alpha,25(OH)2D2 and 1alpha,25(OH)2D7 at the molecular level, especially with regards to the structural differences at the 24R- or 24S-methyl group and a double bond between carbons 22 and 23 in the side chain of 1alpha,25(OH)2D derivatives.
Animals↗
Geographical variation of the skull morphology of the common tree shrew (Tupaia glis).
Geographical variation was examined morphologically in the common tree shrew (Tupaia glis) in some Indochinese and Malayan regions. Osteometrical examination and principal component analysis elucidated the morphological differences among various populations. The populations from southern and western Thailand were distinguished morphologically from the other populations. Variation in males from south Thailand and Kuala Lumpur suggests that the Isthmus of Kra may have an influence on the variation of skull morphology. However, the Isthmus of Kra was not completely considered as a factor of geographical separation in this species, because we could not confirm the separation in skull size and shape between the localities at least in females. While, the Kanchanaburi population in western Thailand was significantly smaller than the other population in skull size, and constituted the morphologically separable group in our study.
Animals↗