Biomedical subjects

N Ueno

Publications and source records attributed to N Ueno.

At least 181 records · Page 10Linked to original sources

PubMed1995

Efficient expression of a heterodimer of bone morphogenetic protein subunits using a baculovirus expression system.

Recombinant baculoviruses as expression vectors for Xenopus bone morphogenetic protein (xBMP)-2, 4 and 7 were generated. The conditioned medium of insect cells infected with the virus for xBMP-2 or 4 showed strong alkaline phosphatase-inducing activity in a mouse osteoblastic cell line, MC3T3-E1, although a large portion of the activity remained in the infected cells. In contrast, xBMP-7 was preferentially secreted into the medium, but had only weak activity. Conditioned media following simultaneous inoculation with the viruses for xBMP-7 and for xBMP-2 or 4 showed a remarkably increased level of activity. The increased activity was clearly separated from other peaks derived from single infection on a cation-exchange column and was found to arise from the disulfide-linked heterodimer consisting of xBMP-4 and 7 subunits by immunoblot analysis. The heterodimer also augmented osteocalcin production and parathyroid hormone-sensitivity more strongly than the homodimers. These results suggest that our expression system provides a convenient source of heterodimeric BMP with high osteogenic differentiation-inducing activity.

3T3 Cells↗

PubMed1995

Genomic organization and chromosomal location of the mouse type I BMP-2/4 receptor.

We have characterized the structure of a mouse bone morphogenetic protein (BMP) type I receptor gene that can bind both BMP-2 and BMP-4. The mouse BMP-2/4 receptor gene is encoded by 11 exons and spans approximately 38-kb. Most of the intron/exon boundaries are not conserved compared to the kinase domain of the related, activin type II receptor. In addition, whereas the activin type II receptor gene contains large introns (> 40 kb), the largest intron of the BMP-2/4 receptor gene is only 6.4-kb. The BMP-2/4 receptor gene (Bmpr) was mapped to mouse chromosome 14. Bmpr is closely linked to Rbp3 in the region containing pugnose, a mutation that alters bone development. Knowledge of the genomic structure of Bmpr provides important information to create Bmpr-deficient mice.

Amino Acid Sequence↗

PubMed1995

BMP-4 regulates the dorsal-ventral differences in FGF/MAPKK-mediated mesoderm induction in Xenopus.

Recent studies on Xenopus development have revealed an increasingly complex array of inductive, prepatterning, and competence signals that are necessary for proper mesoderm formation. In this study, we establish that fibroblast growth factor (FGF) signals through mitogen-activated protein kinase kinase (MAPKK) to induce mesodermal gene expression. We demonstrate that a partially activated form of MAPKK restores expression of the mesodermal genes Xcad-3 and Xbra, eliminated by the dominant-negative FGF receptor (delta FGFR). Similar to the results reported earlier with delta FGFR, expression of a dominant-negative form of MAPKK (MAPKKD) preferentially eliminates the dorsal expression of Xcad-3 and Xbra. We tested whether the regional localization of bone morphogenetic protein-4 (BMP-4) could explain why both MAPKKD and delta FGFR eliminate the dorsal and not the ventral expression of Xcad-3 and Xbra. We show that ectopic expression of BMP-4 is sufficient to maintain the dorsal expression of Xcad-3 and Xbra in embryos containing delta FGFR and that expression of a dominant-negative BMP receptor reduces the dorsal-ventral differences in delta FGFR embryos. These results indicate that regional localization of BMP-4 is responsible for the dorsal-ventral asymmetry in FGF/MAPKK-mediated mesoderm induction.

Animals↗

PubMed1995

Localized BMP-4 mediates dorsal/ventral patterning in the early Xenopus embryo.

Mesoderm is initially induced in the amphibian embryo by events that occur in the early cleavage stages prior to the midblastula transition (MBT) and morphogenesis. These inductive interactions establish the mesoderm at the equator and create a distinction between the dorsal and the ventral regions. After the MBT, zygotic factors pattern the mesoderm and induce the neuroectoderm on the dorsal side of the embryo. Most previous studies have focused on the effects of signals originating in the dorsal mesoderm. We show that BMP-4 transcripts are localized to the ventral side of the gastrula embryo and provide evidence that localized expression of BMP-4 is important for regulating the expression of mesodermal and neural genes. We show that ectopic expression of BMP-4 inhibits the formation of dorsal and lateral mesoderm and reduces the size of the neural plate. Elimination of BMP-4 signaling with a dominant-negative BMP receptor expands the lateral mesoderm and neural plate without expanding the expression of genes along the dorsal midline. These results suggest that BMP-4 may act to oppose the action of dorsalizing signals and neural-inducing signals that originate in the dorsal organizer region. We suggest that BMP-4 may have an analogous role to the Drosophila gene, dpp, in dorsal/ventral pattern formation.

Animals↗

PubMed1995

Serum-induced collagen gel contraction.

PURPOSE: To understand the molecular events underlying disease-related vitreous gel contraction, the effect of serum components on collagen was investigated. METHODS: Bovine vitreous or dermal collagen was incubated with a mixture of transglutaminase (TG; factor XIIIa) and fibronectin (FN), and the biochemical changes of collagen were monitored by gel electrophoresis. In addition, serum-induced changes in the volume of the collagen gel were monitored. RESULTS: Gel electrophoresis revealed a new high-molecular-weight band (M(r) 240,000) presumably due to intermolecular cross-links of collagen peptides and FN. The serum components also were shown to cause a significant decrease in the volume of the collagen gel. CONCLUSION. Collagen gel contraction could be attributed to the collagen-FN-collagen cross-links catalyzed by TG.

Animals↗

PubMed1995

Assessment of portal vein invasion by bile duct cancer using intraductal ultrasonography.

BACKGROUND AND STUDY AIMS: We recently reported on the contribution of intraductal ultrasonography (IDUS) to the regional staging of bile duct cancer, and we present here the first detailed study of the value of IDUS in assessing the portal vein invasion by bile duct cancer. PATIENTS AND METHODS: Preoperative assessment of portal vein invasion was performed by IDUS via a percutaneous tract or via transpapillary route in 18 patients with extrahepatic bile duct cancer. Various probes, with diameters of 1.4, 2.0, 2.4, 2.6, and 3.2 mm, and frequencies of 7.5, 15, 20, and 30 MHz, were used. All patients additionally underwent endoscopic ultrasonography (EUS) and angiography. In the first six cases, the IDUS and EUS images were analyzed retrospectively without the knowledge of operative results or the other imaging tests. In the remaining 12 cases, IDUS and EUS images were prospectively reviewed prior to surgery, without knowledge of the angiographic findings. The gold standard for the results of IDUS, EUS and angiography was the histopathological findings in 17 resected tumors, and the intraoperative findings in one patient who did not undergo resective surgery. RESULTS: IDUS was able to demonstrate the portal vein in all cases. Its accuracy in diagnosing portal vein invasion was 100% for all locations. EUS was useful in assessing portal vein invasion at the middle and distal bile duct (the accuracy was 91%), but was not useful in assessing invasion at the proximal bile duct (the accuracy was 57%). CONCLUSIONS: IDUS proved useful for assessing the extension of cancer invasion into the portal vein, even in proximal bile duct tumors.

Aged↗

PubMed1995

Assessment of hepatic artery invasion by bile duct cancer using intraductal ultrasonography.

BACKGROUND AND STUDY AIMS: This study was performed to clarify the diagnostic accuracy of intraductal ultrasonography (IDUS) in assessing hepatic artery invasion by bile duct cancer. PATIENTS AND METHODS: Preoperative assessment of hepatic artery invasion was performed by IDUS via a percutaneous tract or the transpapillary route in a total of 22 patients with extrahepatic bile duct cancer. The probes used had a diameter of 1.4, 2.0, 2.4, 2.6, and 3.2 mm, and frequencies of 7.5, 15, 20, and 30 MHz. In the first six cases, IDUS images were analyzed retrospectively with no knowledge of the operative results or of the other imaging tests. In the following 16 cases, the IDUS images were prospectively reviewed prior to surgery without knowledge of the angiographic findings. The diagnostic accuracy of IDUS was compared with angiography in all cases, with the histopathological results in 20 resected cases, and with the intraoperative findings in two cases with only surgical exploration. RESULTS: IDUS was able to demonstrate the right hepatic artery in all cases, and its accuracy in diagnosing right hepatic invasion was 100%. However, IDUS was able to visualize the proper hepatic artery in only four cases (18%), and the left hepatic artery in only three cases (14%), respectively. IDUS could not visualize the area outside of the hepatoduodenal ligament, because of its low penetration depth. CONCLUSIONS: IDUS proved useful for assessing the extension of bile duct cancer invasion into the right hepatic artery. However, IDUS did not sufficiently demonstrate the proper hepatic artery and the left hepatic artery for diagnosing vascular involvement.

Aged↗

PubMed1995

Headache associated with aseptic meningeal reaction as clinical onset of Fabry's disease.

This report concerns an 18-year-old boy who is hemizygote for Fabry's disease. Varying degrees of nonpulsating headache crises, lasting from a few hours to several days, began when he was 16 years of age. Painful crises in the extremities, characteristic of Fabry's disease, were not present. Although only occasional, he had several episodes of throbbing headache with vomiting without aura. The meningeal signs were equivocal, although the patient had noninfectious pleocytosis, intracranial hypertension, delayed radioisotope clearance on cisternography, and multiple old cerebral infarcts. Nonsteroidal anti-inflammatory drugs, antidepressants, carbamazepine, and glycerol were of no benefit for his headache. Although its mode of action remains obscure, prednisolone was effective for treating the headache and the aseptic meningeal reaction.

Adolescent↗

PubMed1995

[Inhibitory effects of hydroquinone-alpha-glucoside on melanin synthesis].

Inhibitory effects of hydroquinone-alpha-glucoside (HQ-alpha-G) on the melanogenesis were investigated and compared with those of arbutin. The levels of inhibitory effects of HQ-alpha-G and arbutin on the tyrosinase activity were nearly the same. Inhibitory effects of both compounds on the melanogenesis, were studied using cultured B16 melanoma cells, and HQ-alpha-G was also found to have a similar effect to that of arbutin without inhibiting cell growth. In this experiment, while HQ-alpha-G hardly inhibited cell growth at 1 mM, arbutin inhibit it significantly at the same concentration. From these results it is suggested that HQ-alpha-G as well as arbutin inhibited the melanogenesis by affecting tyrosinase rather than by killing melanocytes. Furthermore, the melanogenesis of guinea-pigs with brown hair was reduced to about 80% by applying them each compound. The great differences in toxicity to normal human keratinocyte were not recognized between these two glucosides. It is, therefore, considered that HQ-alpha-G is an effective and safe ingredient for cosmetics.

Animals↗

PubMed1995

[A study on button-type alkali-manganese battery in Ringer's solution--limited injury factor on the electric discharge in body].

Many cases of tissue injury caused by a button battery appearing as a foreign body have been reported in the otolaryngology field. However, there have been very few studies on the mechanism of tissue injury by batteries. In this study, we inserted a button-type battery into 4cm3 of Ringer's solution, which is similar to serous fluid, at both room temperature (20 degrees C) and body temperature (37 degrees C), and observed the electro-chemical reactions between the negative and positive terminals over 6 hours. We identified the products of these reactions, measured the remaining electromotive force (EMF), and observed the changes in pH and metallic ion concentrations over time. In conclusion, the following three major groups of factors causing tissue injury were suggested: 1) At the positive terminal the HCl acid and HClO produced broke down, and chlorine gas was dissolved into the solution. 2) At the negative terminal, the OH- radical was produced by reduction of water. 3) Potassium hydroxide (KOH), nickel (Ni2+), manganese (Mnn+), chrome (Crn+), and lead (Pb2+) leaked from the battery at the poles, due to oxidation, and were partially dissolved in the serous fluid. These factors may result in serious tissue injury. In addition, each electro-chemical reaction occurred in a very short time at these relatively high temperatures, and as a result, may be the cause of these tissue injuries.

Electrochemistry↗

PubMed1995

Preoperative staging of extrahepatic bile duct cancer with intraductal ultrasonography.

OBJECTIVE: To evaluate the tumor extension of extrahepatic bile duct cancer by means of intraductal ultrasonography (IDUS). METHODS: IDUS preoperatively assessed the tumor extensions in 25 patients with extrahepatic bile duct cancer. The diagnostic accuracy of IDUS was investigated by comparison with other diagnostic imaging modalities in all cases and with histopathological findings of resected specimens in 18 cases. RESULTS: IDUS proved useful in assessing the extension of cancer invasion to the pancreas parenchyma, portal vein, and right hepatic artery. The limitation of the degree of accuracy, based on the group staging criteria, was 68%. IDUS could not assess tumor invasion to the perimuscular loose connective tissue. Therefore, it could not distinguish stage II from stage I. IDUS could not sufficiently assess epicholedochal lymph node metastases (differential diagnosis between stages II and III) and could not demonstrate distant metastases (differential diagnosis between stages IVA and IVB) because of the inevitable attenuation of the echo itself. IDUS could assess cases of stage IVA correctly in 8/8 (100%) cases. The combination of PTC/ERC and IDUS could assess the horizontal extension correctly in 13/18 (72%) cases. The combination of PTC/ERC, percutaneous transhepatic cholangioscopy (PTCS), and IDUS assessed the horizontal extension in 14/15 (93%) cases. CONCLUSION: 1) IDUS, with a high-frequency probe, was very useful for assessing tumor infiltration in the hepatoduodenal ligament. 2) IDUS could not assess tumor extension outside of the hepatoduodenal ligament, but conventional ultrasonography and angiography could compensate for it. 3) The combination of PTC/ERC, PTCS, and IDUS could assess horizontal extension correctly.

Aged↗

PubMed1995

[Changes in vitreous structure caused by oxygen free radicals].

Vitreous liquefaction in humans is considered to be part of the normal ocular aging process and is associated with vitreoretinal pathology. Because hyaluronic acid (HA), one of the main components of the vitreous gel structure, is degraded by reactive oxygen species (ROS) including oxygen free radicals, the structural changes in the vitreous may be caused by ROS. To investigate the effect of ROS on the vitreous gel structure, we treated animal vitreous with ROS, which was generated from various sources. Using riboflavin as a photosensitizer, calf vitreous was irradiated with visible light (two 15-W fluorescent lamps) and found to be considerably liquefied. The liquefaction resulted from HA depolymerization induced by ROS. Because of the small amount of riboflavin naturally present in the vitreous, a riboflavin-sensitized photochemical reaction may contribute to age-related vitreous liquefaction. Hematoporphyrin (HP), which is similar in chemical structure to heme in blood, was also used as a photosensitizer. Irradiation with HP destroyed the calf vitreous gel structure and caused liquefaction. A HP-sensitized photochemical reaction may contribute to vitreous liquefaction observed after vitreous hemorrhage. Because metal ions, including Fe2+ and Cu2+, can catalyze to generate ROS, liquefaction occurred when we treated calf vitreous with Fe2+ or Cu2+ at 4 degrees C. Adding ascorbic acid to the vitreous during the reaction increased the rate of liquefaction. Therefore, metal ion catalyzed ROS may also contribute to vitreous liquefaction, such as that found in an injured eye with siderosis. To investigate the relation between inflammatory cell mediated ROS and vitreous liquefaction, an endotoxin-induced uveitis model was created in the rabbit eye. Upon inflammation, the vitreous gel contracted and released a water-like liquid. Because superoxide dismutase can suppress the liquefaction, the destruction of the vitreous gel structure resulted from ROS generated from inflammatory cells. Although many unknown factors contribute to vitreous liquefaction, ROS may be the main cause of vitreous structure alterations. To prevent or delay the progress of vitreous liquefaction in the normal aging process or vitreous pathology, a new therapeutic procedure based on clear scientific studies is needed.

Aging↗

PubMed1994

Cloning of an isoform of mouse TGF-beta type II receptor gene.

A variant of transforming growth factor-beta type II receptor (TGF-beta RII) cDNA was isolated from a mouse brain cDNA library. The predicted receptor is identical to previously reported mouse TGF-beta RII except that the isoform has an insertion sequence of 25 amino acids in the predicted ligand-binding domain. By the use of reverse transcription-polymerase chain reaction (RT-PCR), transcripts for both isoforms were detected in all tissues and developing embryos examined. The isoform transiently expressed in COS cells showed a similar ligand-binding specificity to authentic TGF-beta RII. These results suggest that the mouse TGF-beta RII gene generates multiple isoforms, possibly by alternative splicing, as reported for activin type IIB receptor; and an isoform which has the extra sequence in the ligand-binding domain is also involved in the TGF-beta signal transduction.

Alternative Splicing↗

PubMed1994

A truncated bone morphogenetic protein receptor affects dorsal-ventral patterning in the early Xenopus embryo.

Bone morphogenetic proteins (BMPs), which are members of the transforming growth factor beta (TGF-beta) superfamily, have been implicated in bone formation and the regulation of early development. To better understand the roles of BMPs in Xenopus laevis embryogenesis, we have cloned a cDNA coding for a serine/threonine kinase receptor that binds BMP-2 and BMP-4. To analyze its function, we attempted to block the BMP signaling pathway in Xenopus embryos by using a dominant-negative mutant of the BMP receptor. When the mutant receptor lacking the putative serine/threonine kinase domain was expressed in ventral blastomeres of Xenopus embryos, these blastomeres were respecified to dorsal mesoderm, eventually resulting in the formation of a secondary body axis. These findings suggest that endogenous BMP-2 and BMP-4 are involved in the dorsal-ventral specification in the embryo and that ventral fate requires induction rather than resulting from an absence of dorsal specification.

Amino Acid Sequence↗

PubMed1994

A truncated bone morphogenetic protein 4 receptor alters the fate of ventral mesoderm to dorsal mesoderm: roles of animal pole tissue in the development of ventral mesoderm.

The biological effects of endogenous bone morphogenetic protein 4 (BMP-4), a member of the transforming growth factor beta family, on embryonic development of Xenopus laevis were investigated by using a functionally defective mutant of the BMP-4 receptor (delta mTFR11), which blocks the BMP signaling pathway. Injection of delta mTFR11 RNA into either the animal pole area or ventral marginal cells at the two-cell stage induced a dorsal phenotype in the explant of ventral mesoderm with animal pole tissue from stage 10+ embryo, even though the normal fate of this explant is a "mesenchymal ball" containing blood cells. These explants with the dorsal phenotype contained muscle, neural tissue, eye capsule, and cement gland. Northern blot analysis showed an increase of cardiac alpha-actin mRNA and a decrease of T alpha-globin mRNA expression, providing further evidence of a conversion from ventral to dorsal phenotype. Although injection of delta mTFR11 RNA did not induce mesoderm in an animal cap culture, the same tissue injected with delta mTFR11 RNA can alter the differentiation fate of uninjected ventral mesodermal explant from ventral to dorsal type, suggesting specific interaction of animal pole tissue and prospective ventral mesoderm in vivo.

Animals↗

PubMed1994

Cloning of a Drosophila melanogaster homologue of the mouse type-I bone morphogenetic proteins-2/-4 receptor: a potential decapentaplegic receptor.

The Drosophila melanogaster (Dm) decapentaplegic (dpp) gene product plays an essential role during several stages of Dm development. The DPP protein is a member of the transforming growth factor-beta (TGF-beta) superfamily and an orthologue of mammalian bone morphogenetic proteins (BMP-2 and -4). Recently, a cDNA clone encoding the mouse Ser/Thr kinase receptor specific for BMP-2/-4 (mTFR11) was isolated. Here, we describe the deduced primary structure, the cytogenetic position and expression pattern of the Dm homologue of mTFR11 (DTFR), a putative DPP receptor. The cytogenetic position of the Dm dtfr gene was mapped to 25D. DTFR has striking homology to mTFR11, especially in the cytoplasmic domain (approx. 63%), including a Ser + Gly-rich box that is characteristic of type-I receptors for the TGF-beta superfamily. Although the amino acid (aa) sequence of the extracellular domain is less conserved than that of the cytoplasmic domain, the extracellular domains of these two molecules were more homologous (approx. 27%) to each other than any other receptors for the TGF-beta superfamily. The spacing of Cys residues in the extracellular domain, which is considered crucial to ligand specificity, is highly conserved in these two receptors. During Dm embryonic development, its expression pattern changes in a dynamic fashion with high levels of expression in mesoderm and midgut, with some relation to dpp mutant phenotypes.

Amino Acid Sequence↗

PubMed1994

Comparison of kinetic properties between MSS4 and Rab3A GRF GDP/GTP exchange proteins.

The kinetic properties of MSS4 are studied in comparison with those of Rab3A GRF. MSS4 stimulates the dissociation of [3H]GDP from the lipid-modified and lipid-unmodified forms of Rab3A to the same extent, although Rab3A GRF is more effective on the lipid-modified form than on the lipid-unmodified form. Both MSS4 and Rab3A GRF are inactive on other Rab/Sec/Ypt family members including at least Rab2, Rab5, and Rab11. Rab GDI inhibits the MSS4 and Rab3A GRF effects on the lipid-modified form of Rab3A, but the doses of Rab GDI necessary for this inhibitory effect on Rab3A GRF are lower than those on MSS4. Moreover, Rab GDI slightly inhibits the Rab3A GRF effect on the lipid-unmodified form of Rab3A, but does not affect the MSS4 effect on the lipid-unmodified form of Rab3A. These results suggest that MSS4 and Rab3A GRF are different GDP/GTP exchange proteins for Rab3A.

GTP-Binding Proteins↗

PubMed1994

Localization of thymosin beta 4 to the neural tissues during the development of Xenopus laevis, as studied by in situ hybridization and immunohistochemistry.

Thymosin beta 4, a polypeptide of 5 kDa, is known to have capacity to regulate actin polymerization by binding to an actin monomer. Distribution of Xenopus laevis thymosin beta 4 (XT beta 4) in the developing Xenopus larva was examined by means of in situ hybridization and immunohistochemistry. Analysis with in situ hybridization revealed that XT beta 4 mRNA becomes gradually localized to the neural tissues, notochord and inner epidermis during neurula stages. Intense accumulation of XT beta 4 mRNA was observed in the ganglions of cranial nerves and in the dorsal region of the spinal cord from stage 26 and onwards. XT beta 4 immunoreactivity (XTI) was observed in larvas at all developmental stages later than stage 26, tail bud embryo. Immunoreactivity was initially distributed to the ganglion of cranial nerve V and Rohon-Beard cells. As the development progressed, the XTI appeared in other neuronal groups. By late tadpole stages (stages 42-47) the XTI was found in the pineal body, oculomotor and trochlear motoneurons of the midbrain, various neurons in the rhombencephalon, ganglions of cranial nerves V, VII/VIII and IX/X. In the spinal cord the XTI was observed in Rohon-Beard cells, dorsal root ganglion cells, motoneurons and other spinal cord neurons. Immunoreactivity was seen in both cell bodies and axons of the neurons. These findings suggest that thymosin beta 4 plays a role in the development of neurons, especially of sensory neurons.

Amino Acid Sequence↗