Biomedical subjects

Y Amemiya

Publications and source records attributed to Y Amemiya.

At least 37 records · Page 2Linked to original sources

PubMed1999

Somatolactin in the white sturgeon and African lungfish and its evolutionary significance.

Somatolactin (SL) is a newly characterized pituitary hormone belonging to the growth hormone-prolactin family. Until now SL has been identified only in teleosts, the most highly derived ray-finned fishes. We report here the cloning of SL cDNAs from two species of bony fish, the white sturgeon (Acipenser transmontanus) and the African lungfish (Protopterus annectens). Overlapping partial cDNA clones corresponding to teleost SLs were amplified by polymerase chain reaction (PCR) from either single-strand or double-strand cDNA from pituitary glands. Excluding the poly(A) tail, the sturgeon SL cDNA is 881 base pairs (bp). This is comparable to 1.0 kb estimated by Northern blot analysis. It contains a 696-bp open reading frame encoding a prehormone of 232 amino acids (aa) with a signal peptide of 24 aa and a mature protein of 208 aa. Excluding the poly(A) tail, the lungfish SL cDNA is 938 bp. This is comparable to 1.1 kb estimated by Northern blot analysis. It contains a 696-bp open reading frame encoding a prehormone of 232 aa with a signal peptide of 26 aa and a mature protein of 206 aa. The deduced aa sequences of sturgeon and lungfish SLs show 76-60% and 65-54% identity with teleost SLs, respectively. These values are significantly higher than the 30% identity with nonteleostean growth hormones and prolactins. Immunostaining of sturgeon pituitary with anti-salmon SL serum demonstrated that the SL cells were localized in the pars intermedia, as in teleosts. The present results demonstrate that the SL gene is present in two divergent lineages, the Actinopterygii (Chondrostei: white sturgeon) and the Sarcopterygii (Dipnoi: African lungfish).

Amino Acid Sequence↗

PubMed1999

A newly characterized melanotropin in proopiomelanocortin in pituitaries of an elasmobranch, Squalus acanthias.

Proopiomelanocortin (POMC) is a precursor for corticotropin (ACTH), three or fewer molecular types of melanotropin (MSH), and beta-endorphin. This protein is thought to have evolved by duplication of MSH genomic segments. Here we report that the POMC in the dogfish, an elasmobranch, contains a fourth type of MSH in addition to classical alpha-, beta-, and gamma-MSH. POMC cDNA was amplified by PCR from double-strand cDNA prepared from dogfish pituitary and ligated into lambdaZAP II. The POMC cDNA is composed of 1315 bp without a poly(A) tail. Northern blot analysis detected a 1.4-kb signal of dogfish POMC mRNA. An open reading frame of the POMC cDNA encodes 320 amino acids, including a signal peptide of 26 amino acids. The dogfish POMC includes gamma-MSH, ACTH, alpha-MSH, beta-MSH, and beta-endorphin at positions 50-61, 115-153, 115-127, 239-256, and 259-294, respectively. In addition to these classical peptides, a newly discovered MSH, which we have termed delta-MSH, is present in dogfish POMC at position (184-195). The four dogfish MSHs can be separated into two groups based on their sequence identities: one pair consists of alpha-MSH and gamma-MSH, and the other consists of beta-MSH and delta-MSH, suggesting that gamma-MSH and delta-MSH may have been duplicated evolutionarily from alpha-MSH and beta-MSH, respectively. gamma-MSH might first have appeared in early gnathostomes because it is absent in the most primitive vertebrate group, the agnathans. delta-MSH, which at this time is found only in chondrichthians, might have appeared after the divergence of chondrichthians from a lineage leading to osteichthyans and tetrapods.

Amino Acid Sequence↗

PubMed1999

Isolation and cDNA cloning of somatolactin in rabbitfish (Siganus guttatus).

We report the isolation and cDNA cloning of somatolactin (SL) from rabbitfish, Siganus guttatus. Rabbitfish SL was isolated from an alkaline extract of the pituitary glands by gel filtration chromatography on Sephadex G-100 and reversed-phase high-performance liquid chromatography. SL was monitored by immunoblotting with flounder SL antiserum. The preparation (yield: 0.86 mg/g wet tissues) contained two immunoreactive bands of 24 and 28 kDa on SDS-PAGE. Overlapping partial cDNA clones corresponding to teleost SLs were amplified by PCR from single-strand cDNA from pituitary glands. Excluding the poly(A) tail, rabbitfish SL cDNA is 1605 bp long. It contains a 693-bp open reading frame encoding a signal peptide of 24 amino acids (aa) and a mature protein of 207 aa. Rabbitfish SL has two possible N-glycosylation sites at positions 11 and 121 and seven half Cys residues. The deduced amino acid sequence shows over 80% identity with those of advanced teleosts like sea bream, red drum, and flounder, 76% with the salmonids, 57% with the eel, and 46% with the goldfish SL.

Amino Acid Sequence↗

PubMed1999

Molecular cloning of lungfish proopiomelanocortin cDNA.

To investigate the evolution of proopiomelanocortin (POMC) from fish to tetrapods, nucleotide sequence of POMC cDNA from a lobe-finned fish, the African lungfish, was determined. POMC cDNA was prepared from lungfish pituitary glands. The POMC cDNA is composed of 1114 bp, excluding a poly-A tail, and encodes 255 amino acids (aa) including a signal peptide of 25 aa. The lungfish POMC contains the segment corresponding to gamma-melanotropin (MSH), corticotropin, alpha-MSH, beta-MSH, and beta-endorphin at positions (50-61), (108-146), (108-120), (178-194), and (197-230), respectively. The lungfish POMC shows greater sequence identity on average with amphibian (62%), ancient ray-finned fishes including acipenseriformes and semionotiformes (62%), and mammalian POMC (52%) than with teleostean (49%), elasmobranch (46%), and agnathan POMC (31%). Thus, the overall structural feature of lungfish POMC is close to the tetrapod POMCs which contain gamma-MSH and the ancient ray-finned fishes POMCs containing gamma-MSH-like sequence. However, amino acid sequence of lungfish beta-endorphin exhibits properties which are specifically observed in the ray-finned fishes and the elasmobranchs.

Adrenocorticotropic Hormone↗

PubMed1999

[Anti IgA antibody].

Explore the source record for details and available documents.

Antibodies, Anti-Idiotypic↗

PubMed1998

The compactness of ribonuclease A and reduced ribonuclease A.

The compactness of ribonuclease A with intact disulfide bonds and reduced ribonuclease A was investigated by synchrotron small-angle X-ray scattering. The Rg values and the Kratky plots showed that non-reduced ribonuclease A maintain a compact shape with a Rg value of about 17.3 A in 8 M urea. The reduced ribonuclease A is more expanded, its Rg value is about 20 A in 50 mM Tris-HCl buffer at pH 8.1 containing 20 mM DTT. Further expansions of reduced ribonuclease A were observed in the presence of high concentrations of denaturants, indicating that reduced ribonuclease A is more expanded and is in neither a random coil [A. Noppert et al., FEBS Lett. 380 (1996) 179-182] nor a compact denatured state [T.R. Sosnick and J. Trewhella, Biochemistry 31 (1992) 8329-8335]. The four disulfide bonds keep ribonuclease A in a compact state in the presence of high concentrations of urea.

Animals↗

PubMed1998

High-Resolution X-ray Diffraction of Muscle Using Undulator Radiation from the Tristan Main Ring at KEK.

High Energy Accelerator Research Organization (KEK), Tsukuba, Japan.High-resolution X-ray diffraction studies on striated muscle fibres were performed using a hard X-ray undulator installed in the Tristan main ring at KEK, Tsukuba, Japan. The performance of the undulator, along with an example experiment which exploited the unique characteristics of undulator radiation, are reported. The vertical divergence angle of the first harmonic of the undulator was approximately 10 micro rad under 8 GeV multi-bunch operating conditions and the peak photon flux density was estimated to be approximately 3 x 10(16) photons s(-1) mrad(-2) (0.1% bandwidth)(-1) (10 mA)(-1). The well collimated X-ray beam from the undulator made it possible to resolve clearly, with high angular resolution ( approximately 700 nm), the closely spaced diffraction peaks on the meridional axis in the X-ray patterns arising from the thick filaments of a striated muscle under static conditions. By fitting the meridional intensity pattern, a model for the molecular arrangement of the constituent proteins in the thick filaments is proposed. These studies of muscle demonstrate the promise of undulator radiation from third-generation sources for high-resolution diffraction studies.

Journal Article↗

PubMed1998

Structure changes in the sol-gel systems of hydrated oxides.

This work was undertaken partly with financial support of the RBRF of the Ministry of Science of the Russian Government (N95-03-09682a) and partly with financial support of the Ministry of Education, Science, Sports and Culture (MONBUSHO) of the Government of Japan.Sols of hydrated aluminium oxide, hydrated zirconium oxide and their mixtures were investigated during the xerogel-amorphous-product-crystalline-product transition by SAXS using synchrotron radiation. In the different temperature regions certain changes in structure and morphology were observed. Some correlation between the characteristics of the initial sols and their mixtures (the size and shape of the pores) was observed. In the temperature region 298-1173 K the characteristics of the mixed sol are defined by the characteristics of the initial sols.

Journal Article↗

PubMed1998

Ti/Al multilayer zone plate and Bragg-Fresnel lens.

By using a helicon plasma sputtering technique, a one-dimensional Ti/Al multilayer zone plate with an outermost layer width of 76 nm has been successfully fabricated. A Bragg-Fresnel lens has been made by combining this zone plate with a Ge(422) crystal. Comparison of the Ti/Al multilayer zone plate with the Ag/Al zone plate is discussed in terms of focusing efficiency.

Journal Article↗

PubMed1998

Object library for a new generation of experiment-controlling applications under the UNIX operating system.

The Interface Object Library based on the Motif extension of the X Windows system and on the ESONE SVIC-VCC Library is presented. Some features of the applications for controlling a synchrotron radiation experiment are discussed. The Interface Object Library is written in the object-oriented C++ language. The library class-hierarchy structure is presented and discussed. Several interfaces were realized in the Interface Object Library: the Windows interface, the CAMAC interface and the interface for supporting the experiment. The behaviour of the objects describing the CAMAC crate and CAMAC block is discussed. The application of these protocols for controlling the fast one-coordinate position-sensitive X-ray detector OD3 is presented.

Journal Article↗

PubMed1998

Transmission-type X-ray linear polarizer with perfect crystals.

Even though conventional X-ray polarizers with multiple-reflection channel-cut structures perform well, they suffer from the disadvantage that the polarized beam is non-stationary as the energy is scanned. In this paper the possibility of using a thin Bragg reflector as a polarizing filter is investigated, so that the transmitted beam (rather than the Bragg-reflected beam) is used. Consequently, the position and direction of the transmitted beam are unchanged as the energy is changed, or even when the polarization direction to be filtered out is changed. Theoretical considerations as well as experimental results on the performance characteristics of the proposed transmission-type X-ray linear polarizer are presented. A polarization ratio, defined as I(H)/I(V), higher than 10(5) was obtained.

Journal Article↗

PubMed1998

X-ray triple refraction and triple absorption in a cobalt-complex crystal.

X-ray triple refraction and triple absorption have been quantitatively measured for the first time. The samples were (100)-, (010)- and (001)-oriented plates of a cobalt-complex monoclinic crystal. The apparatus used was an energy-tunable X-ray polarimeter with a phase retarder. The X-ray energy was scanned over a range of 150 eV near the cobalt K-absorption edge. Both the spectra of ellipticity and rotation of polarization were completely different for each crystal plate, which revealed that the biaxial crystal had three refractive indices and three absorption coefficients in the X-ray region. The Kramers-Kronig relation between the real and imaginary parts of the dielectric anisotropy has been quantitatively confirmed for all three different orientations.

Journal Article↗

PubMed1998

X-ray linear birefringence and linear dichroism in a cobalt crystal measured with a tunable X-ray polarimeter.

X-ray linear birefringence and linear dichroism spectra have been measured simultaneously and quantitatively for the first time. The sample was a hexagonal cobalt single-crystal foil. The apparatus used was an energy-tunable X-ray polarimeter, consisting of a polarizer, a phase retarder and an analyser. The X-ray energy was scanned over a range of 350 eV near the K-absorption edge. The Kramers-Kronig relation between the refraction and absorption anisotropy has been confirmed on an absolute scale. The phase-difference sensitivity of the polarimeter as a polarization inferometer is as small as 2pi/10000, which is about 100 times smaller than that of the Bonse-Hart inferometer.

Journal Article↗

PubMed1998

Molecular structural changes in human fetal tissue during the early stages of embryogenesis.

Low-angle synchrotron X-ray diffraction studies of human fetal extensor tendon and skin collagen, centred in time about the period of first major movement by the fetus, indicate that alignment of the tendon collagen fibrils occurs about this time. At this stage there appears to be no detectable structural difference between tendon and dermis. By three weeks post-partum, marked differences between these tissues can be detected. The distribution of the intermediate filament diameters for all fetal tendons investigated was unimodal (mean 41.2 +/- 0.4 nm) in contrast with that for post-partum tendon which is multimodal. Equatorial periodicities of 353 +/- 3 nm and 32.1 +/- 0.1 nm, consistent with the presence of type IV collagen, were obtained from all fetal samples examined. Neither of these periodicities were observed in post-partum normal tendon and only the larger were observed in post-partum normal skin. The consistency of the results suggest that low-angle X-ray diffraction could be used for the identification of fetal-like tissues found in pathological tissues.

Collagen↗

PubMed1998

Kinetic refolding of beta-lactoglobulin. Studies by synchrotron X-ray scattering, and circular dichroism, absorption and fluorescence spectroscopy.

beta-Lactoglobulin (beta LG) is a predominantly beta-sheet protein with a markedly high helical propensity and forms non-native alpha-helical intermediate in the refolding process. We measured the refolding reaction of beta LG with various techniques and characterized the folding kinetics and the structure of the intermediate formed within the burst phase of measurements, i.e. the burst-phase intermediate. Time-resolved stopped-flow X-ray scattering measurements using the integral intensity of scattering show that beta LG forms a compact, globular structure within 30 ms of refolding. The averaged radius of gyration within 100 ms is only 1.1 times larger than that in the native state, ensuring that the burst-phase intermediate is compact. The presence of a maximum peak in a Kratky plot shows a globular shape attained within 100 ms of refolding. Stopped-flow circular dichroism, tryptophan absorption and fluorescence spectroscopy show that pronounced secondary structure regains rapidly in the burst phase with concurrent non-native alpha-helix formation, and that the subsequent compaction process is accompanied by annealing of non-native secondary structure and slow acquisition of tertiary structure. These findings strongly suggest that both compaction and secondary structure formation in protein folding are quite rapid processes, taking place within a millisecond time-scale. The structure of the burst-phase intermediate in beta LG refolding was characterized as having a compact size, a globular shape, a hydrophobic core, substantial beta-sheets and remarkable non-native alpha-helical structure, but little tertiary structure. These results suggest that both local interactions and non-local hydrophobic interactions are dominant forces early in protein folding. The interplay of local and non-local interactions throughout folding processes is important in understanding the mechanisms of protein folding.

Animals↗

PubMed1998

Analysis of C-KIT, TIE and HTK expression on leukemic cells using flow cytometry: a preliminary report.

C-KIT, TIE and HKT expression on leukemic cells from patients were simultaneously analyzed using flow cytometry. Consistent with previous reports, leukemic cells from most patients with de novo acute myeloid leukemia (AML) were C-KIT-positive (28/35), while those from patients with B-lineage acute lymphoid leukemia (B-ALL) were C-KIT-negative (0/9). In the B-ALL patients, leukemic cells trom seven patients had one or more myeloid antigen such as CD13, CD15 and CD33. In contrast to C-KIT expression, leukemic cells from only one patient with acute monocytic leukemia were TIE-positive. Similarly, leukemic cells from only two patients (one, B-ALL with t(4;11)(q21;q23) and one, essential thrombocythemia in myeloblastic transformation (ET-MBT)) were HTK-positive. These results suggest that among the three receptor tyrosine kinases, C-KIT is the most useful marker for identifying AML.

Antibodies, Monoclonal↗

PubMed1998

Expression profiles of I and sialosyl-I antigens on blood cells: the sialosyl-I antigen is expressed along the monocytic differentiation.

Expression of I and sialosyl-I antigens was examined using specific monoclonal antibodies. The anti-I antibody C6 reacted with monocytes (24%), T cells (55%), B cells (80%) but not with neutrophils (4%), bone marrow (BM) CD34+ cells (2%) or mobilized peripheral blood (PB) CD34+ cells (1%). The anti-sialosyl-I antibody NUH2 reacted with monocytes (38%) and BM CD34+ cells (41%) but not with T cells (2%), B cells (0%) or neutrophils (1%) and it hardly reacted with mobilized PB CD34+ cells (8%). Flow cytometric analyses of CD34+ cells enriched from BM showed that most of the sialosyl-I cells expressed CD13, CD33, CD117, and HLA-DR. Sialosyl-I+ CD34+ cells isolated from BM produced a large number of granulocyte-macrophage colonies and macrophage colonies. Therefore, sialosyl-I+ CD34+ cells are suggested to be colony-forming units granulocyte-macrophage (CFU-GM) and colony-forming units macrophage (CFU-M). BM CD34+ cells cultured in medium containing cytokines produced I+ CD14+ monoblasts and sialosyl-I+ CD14+ monoblasts. Leukemic cells from patients with acute myeloid leukemia were I-negative (32/32) and sialosyl-I-positive (one/32). Leukemic cells from patients with acute lymphoid leukemia were I-positive (four/ten) and sialosyl-I-negative (ten/ten). These results indicate that (1) the I antigen is broadly expressed by monoblasts, monocytes, lymphocytes, and leukemic lymphoblasts, and (2) the sialosyl-I antigen is expressed along the normal differentiation of CFU-GM to monocytes.

Antibodies, Monoclonal↗

PubMed1998

Analysis of peripheral blood CD34+ cells mobilized with granulocyte colony-stimulating factor (G-CSF) using a long-term culture system.

G-CSF administered to healthy volunteers at a dose of 3 microg/kg for 5 days mobilized colony-forming units granulocyte-macrophage (CFU-GM), burst-forming units-erythroid (BFU-E), and long-term culture-initiating cells (LTC-IC) to a maximal level on day 4 or 5. To determine the number of primitive hematopoietic progenitors in the peripheral blood, mononuclear cells (MNCs) or CD34+ cells were cultured in a long-term culture (LTC) system. We defined the colonies produced by cells during LTC at week 2 as differentiated progenitors and those at week 5 as primitive progenitors. G-CSF administered to healthy volunteers increased the number of differentiated progenitors from day 4 and primitive progenitors on days 3-5. Enriched CD34+ cells from healthy volunteers treated with G-CSF (PB-G) or without it (PB-SS), and patients treated with chemotherapy plus G-CSF (PB-CG) were subjected to LTC for 7 weeks. PB CD34+ cells from PB-G contained less primitive progenitors than those from PB-CG. Therefore, in healthy donors administered G-CSF at a dose of 3 microg/kg, the number of PB CD34+ cells should be harvested as much as possible to perform allogeneic peripheral blood stem cell transplantation (PBSCT).

Antigens, CD34↗