Biomedical subjects

Yoko Nagata

Publications and source records attributed to Yoko Nagata.

8 recordsLinked to original sources

PubMed2006

Novel molecular and mechanical properties of egg case silk from wasp spider, Argiope bruennichi.

Araneoid spiders use specialized abdominal glands to produce up to seven different protein-based silks/glues that have various mechanical properties. To date, the fibroin sequences encoding egg case fibers have not been fully determined. To gain further understanding of a recently reported spider silk protein gene family, several novel strategies were utilized in this study to isolate two full-length cDNAs of egg case silk proteins, cylindrical silk protein 1 (CySp1, 9.1 kb) and cylindrical silk protein 2 (CySp2, 9.8 kb), from the wasp spider, Argiope bruennichi. Northern blotting analysis demonstrated that CySp1 and CySp2 are selectively expressed in the cylindrical glands. The amino acid composition of raw egg case silk was closely consistent with the deduced amino acid composition based on the sequences of CySp1 and CySp2, which supports the assertion that CySp1 and CySp2 represent two major components of egg case silk. CySp1 and CySp2 are primarily composed of remarkable homogeneous assemble repeats that are 180 residues in length and consist of several complex subrepeats, and they contain highly homologous C-termini and markedly different N-termini. Our results suggest a possible link between CySp1 and CySp2. In addition, comparisons of stress/strain curves for dragline and egg case silk from Argiope bruennichi showed obvious differences in ultimate strength and extensibility, and similarities in toughness.

Amino Acid Sequence↗

PubMed2006

The presence of high concentrations of free D-amino acids in human saliva.

Free neutral D-amino acids have previously been detected in human plasma, usually accounting for less than 2% of the total free amino acid concentration (D-amino acid ratio) [Nagata, Y., Masui, R., Akino, T., 1992a. The presence of free D-serine, D-alanine and D-proline in human plasma. Experientia 48, 986-988. Nagata, Y., Yamamoto, K., Shimojo, T., 1992b. Determination of D- and L-amino acids in mouse kidney by high-performance liquid chromatography. Journal of Chromatography 575, 147-152. Nagata, Y., Yamamoto, K., Shimojo, T., Konno, R., Yasumura, Y., Akino, T., 1992c. The presence of free D-alanine, D-proline and D-serine in mice. Biochimca et Biiophysica Acta 1115, 208-211]. In the present study to search for the source of free D-amino acids, D- and L-enantiomers of the major non-essential amino acids, i.e., the free form of serine, alanine, proline, aspartate and glutamate were analyzed by HPLC in human saliva, submandibular glands and oral epithelial cells. The D-enantiomer ratios to total of free alanine or proline were 35% and 20%, respectively, in saliva. The ratios of the other D-amino acids were less than 11%. The effect of ingested food and oral bacteria on the saliva amino acid levels was suggested to be insignificant. D-Alanine and d-aspartate were also detected in the submandibular gland in ratios up to 5%, and D-alanine and d-proline were found in oral epithelial cells in ratios of 18% and 5%, respectively. The submandibular gland and oral epithelial cells are suggested to be possible sources of the saliva D-alanine and D-aspartate.

Adult↗

PubMed2006

Large cell neuroendocrine thymic carcinoma coexisting within large WHO type AB thymoma.

Large cell neuroendocrine carcinoma (LCNEC) is a rare type of thymic epithelial tumor. It is recognized as a different entity from other thymic tumors on account of it having a more aggressive biologic behavior and poor prognosis. We report an extremely rare case of a very small, "large cell neuroendocrine thymic carcinoma" coexisting within a large thymoma that could not be detected by usual biopsy. Surgery as the initial treatment has the significance of definitive diagnosis and curative treatment for LCNEC of the thymus. To make a successful differential diagnosis, application of detailed immunohistochemical stains may be of aid, since thymic epithelial tumor is not always morphologically homogenous.

Antineoplastic Agents↗

PubMed2005

Unique molecular architecture of egg case silk protein in a spider, Nephila clavata.

We describe a unique silk protein secreted from the cylindrical silk glands of the spider Nephila clavata. This silk is primarily composed of three proteins, whose transcripts of approximately 16.0, 14.5 and 13.0 kb are homologous to one another in two termini and repetitive units, as determined on Northern blotting. Its overall organization shows that it is similar to other characterized silk proteins, including in the mainly central repetitive region as well as the non-repetitive N-terminal (166 residues) and C-terminal (176 residues) parts. However, up to 90% of the protein consists of highly ordered repetitive structures that are not found in other silks. The repetitive region mainly consists of several types of complexes and remarkably conserved polypeptide repeats. The assembled repeat units (A1B1) contain a high proportion of Ala (30.41%), Ser (25.15%), and residues with hydrophobic side chains (22.22% for Gly, Leu, Ile, Val and Phe combined). The presence of Ser-rich and GVGAGASA motifs suggests the formation of a beta-sheet. The repetitive region is characterized by alternating arrays of hydrophobic and hydrophilic blocks. The results suggested that this egg case silk is an exceptional protein when compared with previously investigated spider silks.

Amino Acid Motifs↗

PubMed2004

[Are tuberculosis advisory committees well-functioning?].

PURPOSE: To evaluate the function status of TB advisory committee to assess treatments of tuberculosis. OBJECT AND METHOD: Estimate by questionnaire sheets to public health nurses attending to seminars on tuberculosis at Research Institute of Tuberculosis. RESULT: 137 answers are available for analysis. Of these, 57 (41.6%) TB advisory committees are estimated not to assess treatments of tuberculosis at all and/or to assess treatments without necessary informations on drug sensitivity in more than around half of the cases. In 13 (16.3%) committees of the other 80, many cases are in fact self-assessed. Number of committees that are estimated to functioning well is only 44 (32.1%). CONCLUSION: Many TB advisory committees are estimated to be malfunctioning from the stand point of assessments of treatment. As TB advisory committee is one of key agency to control drug-resistant tuberculosis, its reform and revitalization are urgently needed.

Advisory Committees↗

PubMed2003

L-Serine, D- and L-proline and alanine as respiratory substrates of Helicobacter pylori: correlation between in vitro and in vivo amino acid levels.

Helicobacter pylori whole cells showed high rates of oxygen uptake with L-serine and L-proline as respiratory substrates, and somewhat lower rates with D-alanine and D-proline. These respiratory activities were inhibited by rotenone and antimycin A at low concentrations. Since pyruvate was produced from L-serine and D- and L-alanine in whole cells, the respiratory activities with these amino acids as substrates occurred via pyruvate. Whole cells showed 2,6-dichlorophenolindophenol (DCIP)-reducing activities with D- and L-proline and D-alanine as substrates, suggesting that hydrogen removed from these amino acids also participated in oxygen uptake by the whole cells. High amounts of L-proline, D- and L-alanine, and L-serine were present in H. pylori cells, and these amino acids also predominated in samples of human gastric juice. H. pylori seems to utilize D- and L-proline, D-alanine and L-serine as important energy sources in its habitat of the mucous layer of the stomach.

2,6-Dichloroindophenol↗

PubMed2002

Rhizoid differentiation in Spirogyra: position sensing by terminal cells.

Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal position in a filament. In the present study, we have analyzed the mechanism for position sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in position sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd(3+) or decrease in extracellular Ca(2+) resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in position sensing by terminal cells.

Calcium↗

PubMed2002

[Identification of familiar people viewed from a variety of viewpoints].

We investigated the visual information used to recognize human head from a variety of viewpoints. Subjects' task was to identify three familiar people from five different views (from the frontal face to the back of the head in steps of 45 degrees). The mean reaction time (RT) was not affected with changing head angles when the image was original face version. RT significantly decreased when the images contained in high spatial frequency (SF) component. Moreover, there was an effective SF range in recognition from each viewpoint, which was the middle range for the frontal face and the higher range for the back of the head. For the profile, there was no change in RT across the ranges of SF. These results suggest that different view-specific information was used on each view for identification, and the recognition of the profile might be unique on familiar face processing.

Adult↗