Biomedical subjects

Kenji Yamada

Publications and source records attributed to Kenji Yamada.

24 records · Page 2Linked to original sources

PubMed2003

High serum levels of menatetrenone in male patients with ossification of the posterior longitudinal ligament.

STUDY DESIGN: This work was performed to investigate the role of vitamin K (VK) in the pathogenesis of ossification of posterior longitudinal ligament (OPLL), by analyzing the biochemical markers of the blood samples of OPLL patients and responses of ligament cells derived from OPLL lesion to VK2. OBJECTIVES: The pathogenesis of OPLL, classified as a form of diffuse idiopathic skeletal hyperostosis, is still unclear. In this study, we investigated the role of menaquinone (VK2) in patients with OPLL (OPLL patients) and the effects of VK2 on ligament cells isolated from OPLL lesion. METHODS: Serum levels of intact osteocalcin, glu-osteocalcin, MK-4, -7 (VK2 variants) and other minerals in spot blood samples were measured in 24 OPLL patients and in 24 age-matched control patients (non-OPLL patients). The cultured cells isolated from an OPLL patient were treated with MK-4. Alkaline phosphatase (Al-p) activity and osteocalcin release were measured after 2 weeks of culture. RESULTS: In the clinical study, the serum MK-4 in male OPLL patients was significantly higher than that in male non-OPLL patients. However, among female patients, the difference was not significant. Although the serum osteocalcin in females was significantly higher than that in males, there was no significant difference between the OPLL and non-OPLL groups. In in vitro study, MK-4 did not increase Al-p activity in the ligament cells isolated from nonossified region of OPLL patient. Osteoblastic activity of the cultured cells was not stimulated by MK-4. CONCLUSION: From these results and previous reports, we propose the possibility of the impediment in VK2 metabolism in OPLL patients. The results also implicate the gender tendency in OPLL, because the difference of serum level of MK-4 in OPLL patients was significant only in male.

Aged↗

PubMed2003

Vacuolar processing enzymes are essential for proper processing of seed storage proteins in Arabidopsis thaliana.

The proprotein precursors of storage proteins are post-translationally processed to produce their respective mature forms within the protein storage vacuoles of maturing seeds. To investigate the processing mechanism in vivo, we isolated Arabidopsis mutants that accumulate detectable amounts of the precursors of the storage proteins, 12 S globulins and 2 S albumins, in their seeds. All six mutants isolated have a defect in the beta VPE gene. VPE (vacuolar processing enzyme) is a cysteine proteinase with substrate specificity toward an asparagine residue. We further generated various mutants lacking different VPE isoforms: alpha VPE, beta VPE, and/or gamma VPE. More than 90% of VPE activity is abolished in the beta vpe-3 seeds, and no VPE activity is detected in the alpha vpe-1/beta vpe-3/gamma vpe-1 seeds. The triple mutant seeds accumulate no properly processed mature storage proteins. Instead, large amounts of storage protein precursors are found in the seeds of this mutant. In contrast to beta vpe-3 seeds, which accumulate both precursors and mature storage proteins, the other single (alpha vpe-1 and gamma vpe-1) and double (alpha vpe-1/gamma vpe-1) mutants accumulate no precursors in their seeds at all. Therefore, the vegetative VPEs, alpha VPE and gamma VPE, are not necessary for precursor processing in the presence of beta VPE, but partly compensates for the deficiency in beta VPE in beta vpe-3 seeds. In the absence of functional VPEs, a proportion of pro2S albumin molecules are alternatively cleaved by aspartic proteinase. This cleavage by aspartic proteinase is promoted by the initial processing of pro2S albumins by VPE. Our overall results suggest that seed-type beta VPE is most essential for the processing of storage proteins, and that the vegetative-type VPEs and aspartic proteinase complement beta VPE activity in this processing.

Amino Acid Sequence↗

PubMed2003

The ER body, a novel endoplasmic reticulum-derived structure in Arabidopsis.

Plant cells develop various endoplasmic reticulum (ER)-derived structures with specific functions. The ER body, a novel ER-derived compartment in Arabidopsis, is a spindle-shaped structure (approximately 10 microm long and approximately 1 microm wide) that is surrounded by ribosomes. Similar structures were found in many Brassicaceae plants in the 1960s and 1970s, but their main components and biological functions have remained unknown. ER bodies can be visualized in transgenic Arabidopsis expressing the green fluorescent protein with an ER-retention signal. A large number of ER bodies are observed in cotyledons, hypocotyls and roots of seedlings, but very few are observed in rosette leaves. Recently nai1, a mutant that does not develop ER bodies in whole seedlings, was isolated. Analysis of the nai1 mutant reveals that a beta-glucosidase, called PYK10, is the main component of ER bodies. The putative biological function of PYK10 and the inducibility of ER bodies in rosette leaves by wound stress suggest that the ER body functions in the defense against herbivores.

Arabidopsis↗

PubMed2003

Effect of 2,5-dimethylpyrazine on uterine contraction in late stage of pregnant female rats.

Effect of 2,5-dimethylpyrazine (2,5-DMP) on oxytocic agent-induced late pregnant uterine contraction in female rats was studied. Oxytocic agents induced-hypercontraction in the late phase of pregnant uterine movements were inhibited by administration of 2,5-DMP. The inhibition of uterine contraction was obtained more strengthening by presence of a low dose of ritodrine hydrochloride than 2,5-DMP alone. These results suggests that 2,5-DMP has an inhibitory action on uterine hypercontraction induced by oxytocic agent through the beta2-adrenoceptor in the pregnant uterus and supports the applicability of relaxing drugs for oxytocic agent-induced accidents.

Animals↗

PubMed2002

S-RNases from self-incompatible and -compatible apple cultivars: purification, cloning, enzymic properties, and pollen tube growth inhibitory activity.

Four S-RNases (RNase associated with self-incompatibility) were purified from the styles of two apple cultivars (Malus domestica), a self-incompatible cv., Starking Delicious (SD), and a self-compatible cv., Megumi (MG). Each cultivar produced two S-RNases and their enzymatic properties such as specific activity, pH optimum, thermal stability, and molecular mass, were characterized. The four S-RNases inhibited the tube growth of apple pollen in an in vitro bioassay at 25 microg/ml (1.0 microM), but did not distinguish self from non-self pollen. The cDNAs of four S-RNases were cloned, and the nucleotide and deduced amino acid sequences were analyzed. The nucleotide sequence of SD-Se RNase was a new one and the other was identical to that of Sc-RNase of cv. Fuji. In MG one was identical to the sequence of SD-Sc RNase and the other to that of Sa-RNase of cv. Golden Delicious except for one base. From results of the isolation amounts and the Western blot analysis for stylar crude extracts the amount of S-RNases in MG was apparently less than that in SD.

Amino Acid Sequence↗

PubMed2002

[A case of subacute transient cerebral dysfunction in a osteosarcoma patient following high-dose methotrexate].

Subacute transient cerebral dysfunction following high-dose methotrexate occurred during neo-adjuvant chemotherapy for an eighteen-year-old male with osteosarcoma in his right femur. The variety of symptoms including hemiparesis and hesitancy of speech occurred 8 days after an administration of high-dose methotrexate (10 g/m2). Evaluations including CT scan of the brain, hemogram and blood chemistry revealed no abnormal findings. The patient found it difficult to sit, speak and eat, but was not confused. He improved in a few days without any specific treatment or residual sequelae. This syndrome was transient and did not recur when he had two additional HD-MTX treatments. The cause of this syndrome remains unknown and does not seem to be predictable. It is, thus, necessary for oncologists to take due care with regard to this syndrome in HD-MTX chemotherapy.

Adolescent↗