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N Ueno

Publications and source records attributed to N Ueno.

At least 19 recordsLinked to original sources
PubMed1992

A carboxyl-terminal truncated version of the activin receptor mediates activin signals in early Xenopus embryos.

The function of a carboxyl-terminal truncated version of the Xenopus activin receptor, encoded by a previously isolated gene XSTK2, was investigated in early embryos. The transcript corresponding to the truncated receptor gene was detected throughout embryonic development although the temporal expression pattern was different from that of an intact receptor. Injection of XSTK2 mRNA into early embryos resulted in the formation of a duplicated body axis. Mesoderm induction as evaluated by the activation of the alpha-actin gene in presumptive ectoderm (animal cap) treated with exogenous activin was significantly enhanced by the injection of XSTK2 mRNA. These results suggest that the truncated receptor is capable of transmitting the activin signal to the same extent as the native receptor.

Actins↗
PubMed1992

Genes for bone morphogenetic proteins are differentially transcribed in early amphibian embryos.

We have previously demonstrated that activin, a member of the TGF-beta family, has a potent mesoderm-inducing activity in Xenopus embryos. In the course of screening for activin-related genes from Xenopus, we have cloned cDNAs for Xenopus homologue of BMP-2, -4 and -7. Northern blot analysis revealed that these BMP genes are maternally encoded and differentially regulated after fertilization. Alkaline phosphatase-inducing assay using the recombinant BMP proteins has shown that at least BMP-2 and -4 have similar activity to mammalian counterparts.

Alkaline Phosphatase↗
PubMed1992

Multiple genes for Xenopus activin receptor expressed during early embryogenesis.

Four distinct cDNAs for activin receptor designated as XSTK2, 3, 8 and 9 have been cloned from a Xenopus laevis cDNA library. The protein structures deduced from the cDNAs have shown that they all have a putative extracellular ligand-binding domain, a single transmembrane domain and cytoplasmic Ser/Thr kinase domain, except that XSTK2 is extremely similar to the XSTK3 gene but lacks a carboxyl-terminal part of the kinase motif. Northern blot analysis showed that all transcripts are maternally inherited. The levels of transcript for XSTK2, 3 and 8 appeared to fluctuate during early development while those for XSTK9 maintain constant.

Activin Receptors↗
PubMed1992

Immunochemical evidence for the presence of advanced glycation end products in human lens proteins and its positive correlation with aging.

Prolonged incubation of protein with reducing sugar proceeds through a series of reactions involving early stage products to the advanced glycation end products with fluorescence, brown color, and cross-linking. Known collectively as the Maillard reaction, these changes have been suggested as factors in diabetic complications and the aging process. The early stage products have been demonstrated in vivo, but evidence for the presence in vivo of the advanced glycation end products has been limited. We sought to provide immunochemical evidence by the preparation and use of polyclonal and monoclonal antibodies to these end products (Horiuchi, S., Araki, N., and Morino, Y. (1991) J. Biol. Chem. 266, 7329-7332) as probes to identify and quantitate such compounds in human lens crystallins. Neither of the antibodies reacted with extracts from infant lenses, but fractions from adult lenses showed a significant reactivity, correlating with lens age. Our findings provide the first immunochemical evidence that human lens crystallins contain advanced glycation end products and that these products increase with tissue age.

Adult↗
PubMed1992

Expression of thymosin beta 4 gene during Xenopus laevis embryogenesis.

In order to investigate the molecular events which take place during gastrulation, extracts from developing Xenopus embryos were analyzed for temporal peptide distribution by high performance liquid chromatography. One peptide peak which became increasingly dominant after gastrulation was purified and partially characterized. The amino acid sequence of enzymic digests showed the peptide is extremely similar to mammalian thymosin beta 4. The peptide was capable of binding actin monomers like mammalian counterparts. Cloning of the Xenopus thymosin beta 4 cDNA showed that only three amino acid substitutions occurred between amphibian and bovine. Northern blot analysis revealed the mRNA is maternally present at a low level and the transcript becomes abundant after gastrulation, supporting the distribution of the peptide.

Amino Acid Sequence↗
PubMed1992

Functional regulation of osteoblastic cells by the interaction of activin-A with follistatin.

A high number of 125I-activin-A binding sites (an apparent Kd of 260 pM and 5,600 sites/cell) were observed on MC3T3-E1 cells, a well characterized osteoblastic cell line. Activin-A has a mitogenic effect on these cells, with the greatest influence being observed on cells in an undifferentiated state, as well as a suppressive effect on the alkaline phosphatase activity. Northern and ligand blotting analyses revealed that these osteoblastic cells produce follistatin, which was down-regulated by retinoic acid treatment. Because follistatin is an activin-A-binding protein, we suggest that activin-A modulates the function of osteoblastic cells by being regulated by follistatin during differentiation.

Activins↗
PubMed1992

Regulation of activin beta A mRNA level by cAMP.

We demonstrated the presence of five species of the activin beta A mRNA in human placenta and one major RNA associated with two minor RNAs of the activin in the fetal membrane. We investigated the effect of 8-bromo-cAMP (8-Br-cAMP) on accumulation of activin beta A subunit mRNA in human fibrosarcoma HT1080 cells. Although low levels of the activin mRNA were detectable in the untreated cells, the one main RNA species was predominantly accumulated by 8-Br-cAMP. We propose that generation of multiple activin mRNAs in the fetal membrane and cAMP-treated HT1080 cells is presumably due to a cell-specific alternative polyadenylation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Impairment of macrophage activation and granuloma formation by protein deprivation in mice.

Protein-calorie malnutrition predisposes to infection by intracellular pathogens, but the basis for this predisposition is unclear. We studied the effect of protein deprivation on mouse peritoneal macrophage function and on granuloma formation during infection by bacille Calmette-Gueŕin (BCG). Injection of lipopolysaccharide (LPS) to induce inflammation elicited fewer peritoneal cells from mice fed a 2.5% protein diet than from mice fed an isocaloric chow in which protein calories constituted 24% of the total. LPS-elicited macrophages from protein-deprived mice demonstrated a reduction in spreading, total cell protein, cell lactate dehydrogenase, and release of superoxide anion (O2-) in response to stimulation. Priming in vitro by interferon (IFN)-gamma for enhanced release of O2- was also significantly impaired in protein-deprived mice. This defect was reversible by repletion with 24% protein diet for 10 days. Impairment of macrophage function in protein-deprived mice was further evidenced by an impaired capacity to express Ia antigen in response to IFN-gamma and by reduced production of IL-1 activity in response to LPS. Infection by BCG in protein-deprived mice was characterized by impaired granuloma development in liver, lungs, and spleen. Thus, in this model, protein deprivation significantly impaired macrophage activation, as assessed by morphologic, metabolic, and functional criteria. This impairment might compromise immune effector mechanisms dependent on macrophage activation, including rejection of intracellular pathogens.

Animals↗
PubMed1992

The effect of oxygen on melanin precursors released from retinal pigment epithelial cells in vitro.

The autoxidation of dopa to melanin in culture media causes toxicity to retinal pigment epithelial (RPE) cells and endothelial cells. The damage is specific to cell type and to the ambient oxygen concentration. To determine whether RPE cells influence the oxidation of dopa to media, we compared light absorbing dopa derivatives in the media exposed to cells with those found in the media incubated without cells. Dopa was extensively oxidized in the presence of RPE cells, and more light absorbing substances were generated with higher dopa and oxygen concentrations. However, an increase in ambient oxygen concentration decreased the quantity of several dopa derivatives which had been formed. The data provided evidence that RPE modulated dopa metabolism. Quinolic derivatives produced from a tyrosinase reaction and dopa-melanin formation moved the peak absorbance wavelength of dopa into the visible range. The spectrum between the dopa-derived compounds in the media has an absorbance at 240-275 nm and a maximum around 300 nm with a shoulder near 375 nm. Gaussian analysis (peak separation) resolved these spectra into five components: a sharp band at 248 nm, a band at 295 nm, a large band at 359 nm, and two broad bands at 459 and 585 nm.

Animals↗
PubMed1992

Metal ion catalyzed liquefaction of vitreous by ascorbic acid: role of radicals and radical ions.

The effect of Fe2+ and Cu2+ on the intact calf vitreous in the presence or absence of exogenous ascorbic acid was investigated in vitro. Liquefaction of vitreous gel was evident in the presence of either ion. The loss of gel structure was greater in the presence of exogenous ascorbic acid than in its absence. As shown by high-performance liquid chromatography, liquefaction was accompanied by depolymerization of vitreous hyaluronic acid which is degraded by .OH, generated by the metal ion catalyzed oxidation-reduction system. The involvement of .OH in this process was also evident from the significant reduction in liquefaction in the presence of the .OH-specific scavenger mannitol.

Animals↗
PubMed1992

Identification of bone morphogenetic protein-2 in early Xenopus laevis embryos.

Polyclonal antibodies capable of reacting with amphibian bone morphogenetic protein (BMP-2 and -4) were raised in rabbits by immunization with a synthetic 21 amino acid peptide which corresponds to a sequence residing in the mature protein of Xenopus BMP-2 (xBMP-2). The antibodies recognized an embryonic BMP as well as mammalian and bacteria expressed recombinant xBMPs. The antibodies detected, under reducing conditions, a 30 kDa protein in the extract of oocytes and embryos during early development. Interestingly, acidification of the extract from each developmental stage yielded a protein band of smaller molecular weight of 18 kDa, which is similar in size to reduced form of mature BMPs purified from mammalian species. Two-dimensional electrophoresis employed to examine the molecular weight of unreduced forms using the antibody, revealed that both molecular forms are monomeric in the embryos. The result suggests that at least BMP-2 mRNA previously detected in early embryos, is translated into peptide but the dimerization may be incomplete or strictly limited in these embryos.

Amino Acid Sequence↗
PubMed1992

[Hypothyroidism followed by interferon-alpha as adjuvant therapy of renal cell carcinoma: a case report].

A 58-year-old male patient was admitted to the hospital complaining of weight loss. Abdominal computerized tomographic (CT) scan disclosed a mass shadow in the left kidney. From the results of further examination, including drip infusion pyelography (DIP) and angiography, he was preoperatively diagnosed as having a left renal tumor. Left radical nephrectomy was performed on March 15, 1990. The lesion was histologically diagnosed as renal cell carcinoma (clear cell subtype, grade 2) confined by the renal capsule (stage I). No distant metastases were detected. Interferon-alpha was administered every other day as adjuvant chemotherapy. After the patient experienced muscle pain in his thighs and shoulders after exercise on February 11, 1991, the serum creatine phosphokinase (CPK) level progressively increased up to 2,329 U/l. On the basis of the results of various examinations reflecting thyroid gland function, he was diagnosed as having primary hypothyroidism due to Hashimoto's disease. Thyroid function improved after administration of triiodothyronine and thyroxine. Interferon has been reported to influence thyroid function, and, in this case, interferon-alpha therapy may have induced the primary hypothyroidism associated with Hashimoto's disease.

Chemotherapy, Adjuvant↗
PubMed1992

Studies on human lens: I. Origin and development of fluorescent pigments.

Fluorescence spectra of normal mature human lenses have been measured and at least eight species with distinct emission characteristics identified. To determine the specific photochemical and photophysical processes responsible for the origin and development of these fluorophores, emission behavior of the products generated by successive irradiation of young human lenses (3-6 y old) as well as of L-tryptophan solution have been systematically monitored. Fluorescent products that resulted from this irradiation were comparable to many of the fluorophores detected in aged lenses, indicating that light plays a major role in the development of these pigments. In addition to photogenerated species, there are other compounds in human lenses, presumably advanced glycosylated end products, with marked fluorescence properties. Several oxidation products of tryptophan including N-formylkynurenine or its derivatives, beta-carboline or its derivatives, and anthranilic acid have been identified in the mature human lens. The development of several photoproducts also was attributed to endogenous ascorbate-mediated Maillard reaction products, which undergo photoconversion by the visible light. Although some of these chromophores could act as photosensitizers, the sensitizing efficiency of many are low. Conversely, the near-UV filtering capability of these colored compounds conceivably could protect the vitreous and retina from development of any photochemical lesion.

Adult↗
PubMed1992

[Studies on fetal middle cerebral artery blood flow velocity waveforms in the intrapartum period].

The effects of uterine contractions on fetal intracranial circulation were studied by means of two dimensional color doppler flow equipment. The Resistance Index of the Middle Cerebral Artery (MCA-RI) was evaluated and the following results were obtained. 1) The MCA-RI value during uterine contraction was significantly higher than that obtained between contractions and the highest MCA-RI value was noted during the active phase, which may mean that the descending fetal head was subjected to the strongest compression at this time. 2) A significant positive correlation was found between intrauterine pressure and the MCA-RI value at any time during labor the course of labor. 3) A significant negative correlation was noted between MCA-RI and FHR. FHR early deceleration (ED) appeared in 67% of the cases with absent end-diastolic flow velocity (AEFV), and in 100% of cases with reverse EFV. It was thus shown that intracranial hemodynamics changed dramatically in the intrapartum period even in the normal fetus.

Blood Flow Velocity↗
PubMed1992

Hyaluronic acid of human skin and post-burn scar: heterogeneity in primary structure and molecular weight.

Hyaluronic acid (HA) was isolated from the dermis and epidermis of normal human skin and from normal and hypertrophic scar tissue, and the molecular properties of this polysaccharide were studied by circular dichroism (CD) and high performance liquid chromatography. The molecular weights of HA of normal skin and post-burn scar tissue range from 62,000 to 180,000. Hexosamine analysis showed no galactosamine contamination and 0.37 to 2.2 w/w% of protein in the HA sample. Uronic acid analysis suggests a heterogeneous distribution of glucuronic and iduronic acids. The CD profiles of these samples are similar, indicating no significant conformational variations among them. These data suggest that the variation in the molecular properties of HA between skin and scar tissue may be due to diversity of embryonic origin between epidermis HA and dermis HA, and to the diversity of the wound-healing process between normal scar HA and hypertrophic scar HA.

Burns↗
PubMed1991

Presence of activin (erythroid differentiation factor) in unfertilized eggs and blastulae of Xenopus laevis.

Activin A, a member of the transforming growth factor beta superfamily, has recently been found to have potent mesoderm-inducing activity on isolated early Xenopus animal-cap cells. We measured the activin activity of the Xenopus egg extract by using an erythroid-differentiating test with Friend leukemia cells. The results showed that an activin homologue is, indeed, contained in unfertilized eggs and blastulae of Xenopus laevis in a considerable amount. This activity was eluted at the same retention time as human activin A when fractionated by reversed-phase HPLC. Furthermore, the fraction containing erythroid-differentiating factor activity had mesoderm-inducing activity on Xenopus animal-cap cells. The mesoderm-inducing activity of this fraction was suppressed when coincubated with follistatin, an activin-binding protein. These results suggest that an endogenous activin may be a natural mesoderm-inducing factor acting in Xenopus embryogenesis.

Activins↗
PubMed1991

Structure and sequence analysis of the human activin beta A subunit gene.

The cloned genomic DNA containing the human activin beta A subunit gene were analyzed by restriction endonuclease mapping, Southern blotting and DNA sequencing. The activin gene is composed of two exons interrupted by the 9-kb intron. The TATA, CCAAT and CT-stretch sequences were found in the 5'-flanking region of the gene. An intronic sequence contained SV40 enhancer core element in the vicinity of the exon 1. In the 3'-flanking region, we identified eight consensus polyadenylation sequences, five ATTTA motifs, CA element consisting of (CA)14, AP-1 binding site and two SV40 enhancer core elements. A dot matrix analysis revealed the high degree of conservation between the human and rat sequences within the 3'-flanking region, suggesting a possible functional significance.

Activins↗