Biomedical subjects

Atsushi Shibuya

Publications and source records attributed to Atsushi Shibuya.

4 recordsLinked to original sources

PubMed2006

Method for calibrating system parameters of a multidirectional interferometers system.

A multidirectional interferometer system has been proposed and developed to measure the position and orientation of a positioning stage. In this method the system parameters, such as positions of the corner-cube reflectors and directions of the rays in the interferometers, must be determined beforehand. However, it is difficult to find ways to determine the system parameters for each different system with necessary accuracy. This paper proposes a systematic method for calibrating the system parameters when the number of the interferometers is larger than the degrees of freedom of the stage. The method is verified for a two-dimensional stage by both simulation and experiment.

Journal Article↗

PubMed2003

Identification of simultaneous mutation of fibrinogen alpha chain and protein C genes in a Japanese kindred.

Afibrinogenaemia usually induces a bleeding tendency during infancy, whereas protein C deficiency increases susceptibility to thrombosis in children or adolescence. Mutations of these genes have been, therefore, established as independent risk factors for coagulation disorders. We describe the homozygous mutation of the fibrinogen alpha chain gene and additional heterozygous mutation of the protein C gene in a male infant who showed prolonged umbilical bleeding after birth. On examination, the plasma fibrinogen was undetectable, and the activity and antigen level of protein C were reduced. The patient showed no fibrinogen Aalpha chain as well as Bbeta and gamma chains by Western blotting. The sequencing analysis showed the homozygous deletion of 1238 bases from intron 3 at position 2008 to intron 4 at position 3245 in the fibrinogen alpha chain gene. Both parents were heterozygous carriers of this mutation. In this patient, an additional mutation was also detected in the protein C gene: the heterozygous deletion of exon 7 at position 6161-6163 or 6164-6166, resulting the deletion of one amino acid (Lys150 or 151). His mother was also a carrier of this mutation. As the simultaneous mutation of the fibrinogen alpha chain and protein C genes has not been previously reported, the influence of the interaction between these two mutations on the clinical manifestations of this patient should be carefully monitored for a long period.

Afibrinogenemia↗

PubMed2002

Successful bone marrow plus cord blood stem cell transplantation in a girl who developed myelodysplastic syndrome from hepatitis-associated aplastic anemia treated with long-term immunosuppressants and growth factors.

A 9-year-old girl who had hepatitis-associated aplastic anemia was treated intermittently with methylprednisolone pulse therapy and growth factors (granulocyte-colony stimulating factor (G-CSF), recombinant human erythropoietin (rhEpo) and cyclosporin A (CyA) for over two years. At this time, there was hematological improvement, but chromosome analysis revealed monosomy 7. After six months, there was progression to myelodysplastic syndrome (MDS) (stage in refractory anemia of excess blasts (RAEB)) with monosomy 7, monosomy 6, marker chromosome and with hematological deterioration. She received bone marrow (1.57 x 10(5) cells kg(-1) (patient body weight)) plus cord blood cell (0.3 x 10(7) cells kg(-1) (patient body weight)) transplantation from her brother, 2 years and 7 months after the diagnosis of hepatitis-associated aplastic anemia. Engraftment was achieved after two weeks, and acute graft-versus-host disease occurred in a mild form after four weeks. Hematological remission has been continuous for 20 months after bone marrow transplantation. Transformation of hepatitis-associated aplastic anemia to MDS with the monosomy 7, monosomy 6 and marker chromosome in this patient was considered to have been related to the administration of high doses of immunosuppressive drugs plus growth factors.

Anemia, Aplastic↗

PubMed2002

Successful reduced-intensity stem cell transplant from one-locus HLA-mismatched unrelated cord blood after rejection of unrelated bone marrow in an infant with myelogenous leukemia.

An 8-month-old girl had acute myelogenous leukemia (EAB M2) that relapsed 5 months after diagnosis during intensive consolidation chemotherapy. She underwent bone marrow transplantation (BMT) from an HLA-A, -B, -C and -DR phenotypically matched, but one locus DRB1 genotypically mismatched unrelated donor, but rejection occurred.Subsequently, she received reduced-intensity transplant (fludarabine/cytosine arabinoside/cyclophosphamide) from one locus HLA-A-mismatched, but DRB1 genotypically matched unrelated cord blood stem cells and remission was induced by acute GVHD (grade II) that progressed to chronic GVHD with involvement of the skin, liver, and gastrointestinal tract. In this case, it seems that remission was induced by an adequate graft-versus-leukemia effect and mild chronic graft-versus-disease due to the HLA-A difference more than DRB1 matched between the patient and the cord blood stem cells.

Bone Marrow Transplantation↗