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Biomedical subjects

K Ibaraki

Publications and source records attributed to K Ibaraki.

At least 19 recordsLinked to original sources
PubMed1999

A novel two-site enzyme immunoassay reveals the regional distributions of and developmental changes in GluR1 and NMDAR1 protein contents in the rat brain.

Glutamate receptors, including the alpha-amino-3-hydroxy-4-methylisoxazole-4-propionic acid (AMPA) and NMDA receptors, play an important role in neural development and synaptic plasticity in the brain. To date, it has been difficult to correlate accurately individual biochemical phenomena with quantitative and qualitative changes in receptors occurring in specific neurons or synapses. In the present study, we established a two-site enzyme immunoassay for two key subunits of the AMPA and NMDA receptors. Its sensitivities were extremely high, 30 pg for GluR1 and 15 pg for the NMDAR1 receptor containing the C2 exon [NMDAR1(C2)], which enabled us to measure their contents in a few milligrams of hippocampal tissue. Regional and developmental variations in receptor protein levels were much more marked than those reported for mRNA: The absolute GluR1 protein content was highest in the rat hippocampus, whereas the NMDAR1(C2) content was high in all the forebrain regions examined. GluR1 protein levels increased most markedly during the second and third weeks of postnatal life, whereas NMDAR1(C2) content increased during the first postnatal week. In the adult rat brain, the ratio of GluR1 protein to NMDAR1 protein was markedly lower in neocortical regions (approximately 2%) and the highest in cerebellum (22%). Therefore, this two-site enzyme immunoassay is a specific and unique method that enables us to measure absolute tissue contents of the glutamate receptors and will lead to further important discoveries on the biochemical alterations of these receptors.

Animals↗
PubMed1999

Clarithromycin associated with torsades de pointes.

Two cases of QT prolongation and torsades de pointes (TdP) are presented. The patients had been taking clarithromycin (400 mg/day) for respiratory disease. Although erythromycin is reportedly associated with TdP, this is the first report of clarithromycin associated with TdP in the absence of other drugs already known to produce QT prolongation.

Aged↗
PubMed1998

Mobilization of a congenital proximal radioulnar synostosis with use of a free vascularized fascio-fat graft.

We present the results of a new mobilization procedure for the treatment of a congenital proximal radioulnar synostosis in seven patients. The operative procedure included separation of the synostosis and placement of a free vascularized fascio-fat graft to prevent recurrent ankylosis. The average age at the time of the operation was eight years and two months (range, six years and four months to eleven years and ten months). All of the patients were boys who had no other congenital anomalies. The radial head was dislocated in all seven patients (anteriorly in two and posteriorly in five). The final four index operations included an osteotomy of the radius in order to reduce the dislocated radial head. The average duration of follow-up was three years and eight months (range, two years and four months to four years and five months). Preoperatively, the patients had had difficulty with holding a bowl of soup and accepting objects, such as coins, into the palm. Postoperatively, they were able to perform these activities. None of the patients had recurrent ankylosis or loss of the flap. The average supination was 26 degrees (range, 10 to 45 degrees), and the average pronation was 45 degrees (range, 10 to 80 degrees). The four patients who had had an osteotomy of the radius in addition to the index procedure did not have a dislocation of the radial head and had an average arc of motion of 83 degrees of pronation and supination. The three patients who had not had an osteotomy had a dislocation of the radial head and an average arc of motion of 40 degrees after the index procedure. These findings demonstrate that separation of a congenital radioulnar synostosis with a vascularized fascio-fat graft and osteotomy of the radius can achieve pronation and supination of the forearm.

Adipose Tissue↗
PubMed1996

Ventromedial hypothalamus suppresses splenic lymphocyte activity through sympathetic innervation.

The ventromedial hypothalamic nucleus (VMH) has been proposed to be a locus intimately associated with sympathetic facilitation in peripheral tissues. To investigate a possible role of the VMH in controlling peripheral immune functions, we examined the effects of VMH stimulation on proliferative activity of lymphocytes isolated from the spleen in rats. Electrical stimulation of the VMH (2 s at every 30 s for 30 min) caused a remarkable decrease in the mitogenic response of splenic lymphocytes to Concanavalin A, whereas the stimulation of other hypothalamic regions such as the paraventricular nucleus did not show any significant effects. The suppressive effect of VMH stimulation was not influenced after adrenalectomy, suggesting a minor role of the adrenocortical system. In contrast, pretreatments with a ganglionic blocking agent (chlorisondamine) and a beta-adrenergic receptor antagonist (propranolol) completely reversed the suppressive effect. Surgical severing of the sympathetic nerves entering the spleen also reversed the effect of VMH stimulation. Together with the previous finding that VMH stimulation activates the splenic sympathetic nerves, it is concluded that the VMH suppresses the proliferative activity of splenic lymphocytes through the activation of sympathetic nerves via the beta-adrenergic pathway.

Adrenal Cortex↗
PubMed1995

Identification of four different forms of syntaxin 3.

cDNAs for four different forms of syntaxin 3 were cloned from a mouse brain cDNA library, and the proteins encoded by these clones were named syntaxin 3A (previous syntaxin 3), 3B, 3C and 3D. Syntaxin 3B contained a different sequence in the carboxyl terminal region from that of syntaxin 3A. The amino terminal region of syntaxin 3C contained an 18 amino acid sequence instead of a 34 amino acid sequence present in syntaxins 3A and 3B. Syntaxin 3D consisted of only 86 amino acids and lacked any putative transmembrane segments. These forms of syntaxin 3 are probably generated by alternative splicing of the primary transcript of syntaxin 3 gene. Cytoplasmic portions of syntaxins 3A and 3B but not of syntaxin 3C or 3D bound to Munc-18/n-sec1.

Alternative Splicing↗
PubMed1995

Mouse tetranectin: cDNA sequence, tissue-specific expression, and chromosomal mapping.

Tetranectin is a plasminogen-binding tetrameric protein originally isolated from plasma. Expression of tetranectin appears ubiquitous, although particularly high expression is noted in the stroma of malignant tumors and during mineralization. To dissect the molecular basis of tetranectin gene regulation, mouse tetranectin cDNA was cloned from a 16-day-old mouse embryo library. Sequence analysis revealed a 992-bp cDNA with an open reading frame of 606 bp, which is identical in length to the human tetranectin cDNA. The deduced amino acid sequence showed high homology to the human cDNA with 76% identity and 87% similarity at the amino acid level. Sequence comparisons between mouse and human tetranectin and some C-type lectins confirmed a complete conservation in the position of six cysteines as well as numerous other amino acid residues, indicating an essential structure for potential function(s) of tetranectin. The sequence analysis revealed a difference in both sequence and size of the noncoding regions between mouse and human cDNAs. Northern analysis of the various tissues from mouse, rat, and cow showed the major transcript(s) to be approximately 1 kb, which is similar in size to that observed in human. Although additional minor bands of 1.5 and 3.3 kb were found in Northern blots, RT-PCR (reverse transcription polymerase chain reaction) analysis failed to provide evidence that these minor bands are products of the tetranectin gene. Finally, the genetic map location for this gene, Tna, was determined to be on distal mouse Chromosome (Chr) 9 by analysis of two sets of multilocus crosses.

Amino Acid Sequence↗
PubMed1995

Free vascularized medial plantar flap with functioning abductor hallucis transfer for reconstruction of thenar defects.

We devised a medial plantar flap with a functioning abductor hallucis for simultaneous reconstruction of thenar skin and muscle defects. The anatomy of the flap was studied in five cadaver dissections before surgical attempts were made in patients, who in this series included three men and one woman (average age 38 years, range 26 to 50 years). All patients were followed a minimum of 3 years (average 3 years and 9 months). In all cases, voluntary abduction of the thumb by the transferred abductor hallucis was achieved and confirmed by electromyography. The functioning medial plantar flap provides not only stable skin to the thenar area with sufficient thenar bulk but also satisfactory abduction of the thumb.

Adult↗
PubMed1995

Molecular cloning and sequence of bovine Msx-1 homeobox-containing gene cDNA from a bovine odontoblast library.

Screening of a bovine odontoblast cDNA library from developing incisor with murine Msx-1 and Msx-2 cDNA probes led to the isolation of three positive clones. All of them encoded for a sequence of a protein containing 297 amino acids. The responsible gene was designated as bovine Msx-1 (bMsx-1) due to the high homology with the human MSX-1 and mouse Msx-1 sequences.

Amino Acid Sequence↗
PubMed1994

Cloning and sequence analysis of bovine bone sialoprotein cDNA: conservation of acidic domains, tyrosine sulfation consensus repeats, and RGD cell attachment domain.

We isolated and sequenced a cDNA encoding bovine bone sialoprotein (BSP) using a bovine cDNA library made from mRNA isolated from bone-derived cell cultures and ligated to a phage lambda gt11. One of the cDNA clones isolated from this library had a 1800 base pair long insert and was found to contain the entire protein-encoding region. The deduced protein sequence revealed a 310 amino acid protein containing a signal peptide sequence of 16 hydrophobic amino acids. The protein sequence shows remarkable conservation with previously published human and rat sequences (more than 80% similarity for both species). The potential functional domains of BSP, including three acid amino acid-rich sequences, tyrosine sulfation consensus repeats, and the RGD cell binding sequence, are all present in the bovine sequence. Northern analysis of RNA from different bovine tissues indicated the presence of BSP message in bone but not in other nonmineralized tissues, confirming that bone is the major site of BSP message production.

Amino Acid Sequence↗
PubMed1994

The role of calcitonin gene-related peptide (CGRP) in macrophages: the presence of functional receptors and effects on proliferation and differentiation into osteoclast-like cells.

It has been shown that both calcitonin gene-related peptide (CGRP) and amylin bind weakly to calcitonin (CT) receptors in osteoclast-like cells formed in vitro and inhibit bone resorption by a cAMP-dependent mechanism. Osteoclasts are thought to be derived from cells of the monocyte macrophage lineage, in which CGRP, but not CT, induces cAMP production. In this study, we determined the presence of functional receptors for CGRP in mouse alveolar macrophages and the effects of this peptide on proliferation and osteoclastic differentiation in mouse alveolar and bone marrow-derived macrophages. Human CT did not stimulate cAMP production in macrophages. Human CGRP stimulated cAMP production in mouse alveolar macrophages and bone marrow-derived macrophages dose-dependently. Human amylin, which has 43% homology with human CGRP, also stimulated these macrophages to produce cAMP, but only at a 100-fold higher concentration. The increment in cAMP production induced by human CGRP and amylin was abolished by the addition of human CGRP(8-37), a selective antagonist for CGRP receptors. Specific binding of [125I]human CGRP to alveolar macrophages was detected (dissociation constant, 2.5 x 10(-8) M; binding sites, 1.4 x 10(4)/cell). Amylin, but not CT, displaced the bound [125I]human CGRP from alveolar macrophages, but at a 100-fold higher concentration. No specific binding of [125I]human CT and [125I]human amylin to alveolar macrophages could be detected. Pretreatment with human CGRP for 24 h dose-dependently suppressed DNA synthesis in alveolar macrophages induced by granulocyte-macrophage colony-stimulating factor (GM-CSF). CGRP also suppressed the number of macrophage colonies formed from bone marrow cells induced by macrophage colony-stimulating factor (M-CSF).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A potential role for tetranectin in mineralization during osteogenesis.

Tetranectin is a protein shared by the blood and the extracellular matrix. Tetranectin is composed of four identical, noncovalently bound polypeptides each with a molecular mass of approximately 21 kD. There is some evidence that tetranectin may be involved in fibrinolysis and proteolysis during tissue remodeling, but its precise biological function is not known. Tetranectin is enriched in the cartilage of the shark, but the gene expression pattern in the mammalian skeletal system has not been determined. In the present study we have examined the expression pattern and putative function of tetranectin during osteogenesis. In the newborn mouse, strong tetranectin immunoreactivity was found in the newly formed woven bone around the cartilage anlage in the future bone marrow and along the periosteum forming the cortex. No tetranectin immunoreactivity was found in the proliferating and hypertrophic cartilage or in the surrounding skeletal muscle. Using an in vitro mineralizing system, we examined osteoblastic cells at different times during their growth and differentiation. Tetranectin mRNA appeared in the cultured osteoblastic cells in parallel with mineralization, in a pattern similar to that of bone sialoprotein, which is regarded as one of the late bone differentiation markers. To explore the putative biological role of tetranectin in osteogenesis we established stably transfected cell lines (PC12-tet) overexpressing recombinant tetranectin as evidenced by Northern and Western blot analysis and immunoprecipitation. Both control PC12 cells and PC12-tet cells injected into nude mice produced tumors containing bone material, as evidenced by von Kossa staining for calcium and immunostaining with bone sialoprotein and alkaline phosphatase antiserum. Nude mice tumors established from PC12-tet cells contained approximately fivefold more bone material than those produced by the untransfected PC12 cell line or by the PC12 cells transfected with the expression vector with no insert (Mann Whitney rank sum test, p < 0.01), supporting the notion that tetranectin may play an important direct and/or indirect role during osteogenesis. In conclusion, we have established a potential role for tetranectin as a bone matrix protein expressed in time and space coincident with mineralization in vivo and in vitro.

Animals↗
PubMed1994

Effects of dibutyryl cyclic AMP on hyaluronan and proteoglycan synthesis by retroocular tissue fibroblasts in culture.

Deposition of glycosaminoglycan is one of the histological features of Graves' ophthalmopathy. Although retroocular tissue fibroblasts are considered to be responsible for glycosaminoglycan accumulation, it is not known what is stimulating the fibroblasts. There are studies which are in support of and against the role of anti-TSH receptor antibodies in the pathogenesis of Graves' ophthalmopathy. TSH-receptor antibodies increase cAMP as a second messenger in thyroid cells. We studied the effects of dibutyryl cyclic AMP (Bt2 cAMP) on glycosaminoglycan synthesis by retroocular tissue fibroblasts in order to known whether cAMP can modulate glycosaminoglycan synthesis. Retroocular tissue fibroblasts mainly synthesize hyaluronan, the large chondroitin sulfate proteoglycan and the small chondroitin sulfate proteoglycan as glycosaminoglycan in cell culture. The amount of hyaluronan synthesis was measured as [3H]glucosamine incorporation into macromolecule susceptible to hyaluronidase digestion (from Streptomyces hyaluronlyticus). The amount of proteoglycan synthesis was measured as [35S]sulfate incorporation into macromolecules in medium and cell layer fraction. Proteoglycans in medium were further separated into the large proteoglycan and the small proteoglycan on a Superose 6 column. Bt2 cAMP increased both hyaluronan and proteoglycan synthesis by retroocular tissue fibroblasts, especially stimulating the secretion of the large proteoglycan synthesis by retroocular tissue fibroblasts, especially stimulating the secretion of the large proteoglycan. Effects of Bt2 cAMP on glycosaminoglycan synthesis were then compared with those in adult skin fibroblasts. Although the magnitude of response between the two was indistinct, the stimulation of the large proteoglycan synthesis by Bt2 cAMP was more prominent in retroocular tissue fibroblasts. The results suggest that the regulation of glycosaminoglycan synthesis by retroocular tissue fibroblasts is different from that by adult skin fibroblasts. Although further studies are required to determine its actual role, cAMP stimulates glycosaminoglycan synthesis by retroocular tissue fibroblasts and underlies the mechanism in Graves' ophthalmopathy.

Adult↗
PubMed1994

Analysis of proteoglycan synthesis by retro-ocular tissue fibroblasts under the influence of interleukin 1 beta and transforming growth factor-beta.

Retro-ocular tissue fibroblasts are supposed to be responsible for the deposition of glycosaminoglycan in Graves' ophthalmopathy. We have reported in a preliminary fashion that interleukin 1 beta (IL-1 beta) and transforming growth factor-beta (TGF-beta) increased the rate of [35S]sulfate incorporation into proteoglycans two to five times the control in culture of retro-ocular tissue fibroblasts. The increase in the rate of [35S]sulfate incorporation into proteoglycan will occur as a result of: (a) net increase of proteoglycan synthesis; (b) elongation of glycosaminoglycan chains; (c) increased number of glycosaminoglycan chains; (d) oversulfation of glycosaminoglycan chains; (e) increase in cell number; (f) decreased rate of degradation. We have analyzed which mechanism is important for the increase of [35S]sulfate into proteoglycans observed in human retro-ocular tissue fibroblasts under the influence of cytokines. The last two possibilities (e, f) were ruled out because during the observation period there was no consistent proliferation of the cells and no decrease in the rate of degradation of proteoglycan examined by pulse-chase experiment. Cytokines did not change the size of glycosaminoglycan chains released from proteoglycan as measured by alkaline borohydride treatment, ruling out (b). Disaccharide analysis by HPLC after chondroitin sulfate ABC digestion revealed that glycosaminoglycan mainly contains monosulfated chondroitin disaccharides and that oversulfation was not observed under the influence of IL-1 beta or TGF-beta, ruling out (d). The capacity to synthesize glycosaminoglycan chain in the presence of an artifical acceptor of chain elongation, beta-D-xylodide, was increased significantly by IL-1 beta but not obviously so by TGF-beta.(ABSTRACT TRUNCATED AT 250 WORDS)

Connective Tissue↗
PubMed1993

Partial characterization of a novel 'GGA' factor which binds to the osteonectin promoter in bovine bone cells.

Osteonectin (On)/SPARC (secreted protein, acidic and rich in cysteine) is a highly conserved extracellular matrix protein found in bone and other tissues throughout vertebrate evolution. In previous studies, approximately 500 bp of DNA 5' to the transcription start point (tsp) and a part of exon 1, including homopurine (Rn)/homopyrimidine (Yn)-rich sequences (the 'GGA box' and its complements), was demonstrated to be important in upregulation of On gene expression in a cell-specific manner. The purpose of this study was to decipher the transcriptional regulation of On through its cis- and trans-acting elements. DNase I footprinting analysis indicated protein binding which may be related to the transcriptional factors, AP2, SP1 and a novel 'GGA' factor which binds to the 3' end of the promoter (-286 to +43 to the tsp). Comparisons of footprinting between nuclear extracts of bone (On-expressing) cells and Madin and Darby bovine kidney (MDBK) (nonexpressing) cells indicate that 'GGA' factor binding to a purine GGGGA/GGA-rich sequence is cell-type specific and therefore may be involved in the cell-specific expression of this gene. From ultraviolet (UV)-crosslinking experiments, this 'GGA' factor was demonstrated to be a single 40-kDa protein.

Animals↗
PubMed1993

Packing with high-porosity hydroxyapatite cubes alone for the treatment of simple bone cyst.

In 23 patients, simple bone cysts were treated by curettage followed by packing the cavity with cubes of high-porosity hydroxyapatite (HA). In 22 patients, HA was packed exclusively without autogeneic bone graft. Except in one patient who sustained pathologic fracture at the femoral diaphysis, HA was packed with a fibula strut graft. Each case had an uneventful postoperative course and was followed, on average, two years. Complete healing without cyst recurrence occurred in 18 cases (78%). In three cases--all rapidly growing children--a new cyst appeared between the epiphyseal plate and the HA packing, but the original cysts did not recur. In two multiloculated cysts, the cavities were not filled fully and healing was incomplete, yet there was no cyst recurrence. In the entire group, new bone surrounding HA was roentgenographically evident within an average of 2.3 months. Thus, the result of packing high-porosity HA for simple bone cysts compares favorably with the cure rates reported either with autogeneic bone graft, or topical steroid injection.

Adolescent↗
PubMed1992

Bone matrix mRNA expression in differentiating fetal bovine osteoblasts.

In the accompanying study, we report an in vitro culture system from bovine bone cells that can be applied to investigate bone cell growth and differentiation. In this system, bovine bone cells placed in mineralization medium formed multilayers (days 2-3), began deposition of mineral (days 5-6), and eventually acquired a mineralized matrix sheet (days 14-20) through the stages of mineralizing nodules and trabecular-like structure. In the current study we used this system to investigate the relative expression of bone matrix genes that may play an important role in bone development and metabolism. alpha 1(I)-collagen, alkaline phosphatase, osteonectin, biglycan (PgI), decorin (PgII), osteopontin, and bone sialoprotein mRNA gene expression were measured on days 0, 2, 6, 10, and 20 (date when the cells were placed in mineralization medium as day 0). Total RNA was purified and analyzed by northern blot using radiolabeled cDNA encoding these genes. To comprehend the relationship between gene expression and mineralization, total calcium content in the cultures was also measured. During the culture period we observed several very different gene expression profiles. The expression of both alpha 1(I)-collagen and biglycan increased 3- to 4-fold by day 6 and then returned to basal levels by day 20. The osteonectin gene was highly expressed throughout the culture, with no significant increase in induction found during any time of culture. A significant induction of alkaline phosphatase (13.8-fold) gene expression was observed by day 6. Osteopontin showed a similar profile to that of alkaline phosphatase but had a much greater level of relative expression (26-fold) compared to day 0. Interestingly, downregulation during mineral accumulation seemed a common occurrence among many of the genes measured. In contrast, the bone sialoprotein gene showed a significant and distinct expression pattern, increasing rapidly after the onset of mineralization on day 6 and ultimately reaching 140-fold that of day 0. Decorin (Pg II) showed an increasing pattern, with the final relative level of induction 5-fold on day 20. These data suggest that the development of the mature osteoblastic phenotype, complete with the ability to produce a thick mineralized matrix, requires the differential regulation of a series of genes and their gene products over the culture period.

Alkaline Phosphatase↗
PubMed1992

Effects of non-collagenous proteins on the formation of apatite in calcium beta-glycerophosphate solutions.

The effects of the non-collagenous proteins; osteonectin, bone Gla protein and dentine phosphoprotein, on the formation of apatite were studied in calcium beta-glycerophosphate solutions containing catalytic amounts of alkaline phosphatase under physiological conditions. In the system used, calcium phosphate precipitates de novo at levels of supersaturation precisely determined through the enzymatic hydrolysis of beta-glycerophosphate. At 1.7 mM of calcium beta-glycerophosphate, calcium phosphate precipitated when inorganic phosphate accumulated to about 1.4 mM. In the presence of the proteins, however, a greater accumulation of inorganic phosphate was needed for calcium phosphate to precipitate, suggesting that a higher degree of supersaturation, though still a slight undersaturation with respect to dicalcium phosphate dihydrate, is required for calcium phosphate to precipitate in the presence of the proteins. At the same protein (micrograms/ml) concentration, dentine phosphoprotein was approximately four times as effective as bone Gla protein, which was about twice as effective as osteonectin in delaying precipitation. The proteins also retarded subsequent crystal growth, with apatite formed in the presence of the more inhibitory proteins having the smallest crystals, especially in width.

Alkaline Phosphatase↗