Biomedical subjects

Takuya Hirata

Publications and source records attributed to Takuya Hirata.

6 recordsLinked to original sources

PubMed2006

Mucosal acid causes gastric mucosal microcirculatory disturbance in nonsteroidal anti-inflammatory drug-treated rats.

The mechanism by which nonsteroidal anti-inflammatory drugs (NSAIDs) suppress gastric mucosal blood flow is not fully understood, although the depletion of mucosal prostaglandin E2 has been proposed as one possible explanation. We investigated the role of gastric acid on gastric mucosal blood flow in NSAID-treated rats. A rat stomach was mounted in an ex vivo chamber, and gastric mucosal blood flow was measured sequentially in a 5-mm2 area of the gastric corpus using a scanning laser Doppler perfusion image system. Results showed that diclofenac (5 mg/kg s.c.) and indomethacin (10 mg/kg s.c.) did not affect gastric mucosal blood flow, although both strongly decreased mucosal prostaglandin E2 when saline was instilled into the gastric chamber. On replacement of the saline in the chamber with 100 mM hydrochloric acid, these drugs caused a decrease in gastric mucosal blood flow levels within 30 min. The specific cyclooxygenase (COX)-2 inhibitors celecoxib (50 mg/kg s.c.) and rofecoxib (25 mg/kg s.c.) did not affect mucosal prostaglandin E2 level, nor did they decrease gastric mucosal blood flow, even when hydrochloric acid was added to the chamber. Furthermore, measurement of vasoconstrictive factors present in the mucosa showed that endothelin-1 levels increased after administration of diclofenac s.c. in the presence of intragastric hydrochloric acid. This indicates that the presence of mucosal hydrochloric acid plays an important role in the NSAID-induced decrease in gastric mucosal blood flow, while the COX-1-derived basal prostaglandin E2, which is unlikely to control gastric mucosal blood flow itself, protects microcirculatory systems from mucosal hydrochloric acid.

Animals↗

PubMed2005

Sonographic shift of hypervascular liver tumor on blood pool harmonic images with definity: time-related changes of contrast-enhanced appearance in rabbit VX2 tumor under extra-low acoustic power.

We elucidated the features of the time-related contrast-enhanced ultrasound appearance of hypervascular liver tumor using Definity, which has no accumulation activity in the liver. Ten rabbits with VX2 tumors broadcast into the liver were used. Changes in contrast-enhanced sonograms were evaluated by real-time observation (FR 15 Hz) of harmonic imaging under extra-low MI (MI 0.065) with Definity, and their intensity changes were analyzed. Hepatic angiography (4/10) and histopathological examination (10/10) were performed to investigate the tumor vascularity. VX2 tumors were hypervascular on angiogram (4/10) and histology (10/10). They showed time-related sonographic appearance changes from hyperechoic to hypoechoic, which were confirmed by quantitative intensity analysis. Hypervascular VX2 tumors showed characteristic time-related shift on contrast-enhanced sonograms in real-time and extra-low MI harmonic images with Definity. These findings may be useful for the ultrasound diagnosis of human hypervascular liver tumor like hepatocellular carcinoma with blood-pool contrast agent.

Acoustics↗

PubMed2005

Thrombopoietin in the cerebrospinal fluid of patients with aseptic and bacterial meningitis.

Despite the recent evidence of the localization of thrombopoietin (TPO) and its receptor in the central nervous system (CNS), TPO protein concentrations in the cerebrospinal fluid (CSF) remained to be clarified. We previously reported that serum TPO is increased in children with meningitis. To determine changes in TPO concentrations in the CSF by meningitis and to explore the relationship between serum and CSF TPO concentrations, we measured TPO concentrations in 110 CSF samples and 33 serum/CSF pairs from 11 bacterial meningitis, 49 aseptic meningitis, and 50 nonmeningitis children. In only 12% (13 of 110) of CSF samples (0 bacterial meningitis, 8 aseptic meningitis, and 5 controls), TPO concentrations could be determined (24.1 +/- 29.0 pg/ml). CSF TPO concentrations did not significantly differ among the three groups and did not correlate with age. TPO concentrations in all serum samples were detectable, and mean concentrations in bacterial meningitis (510.6 +/- 237.0 pg/ml) were significantly higher than those in aseptic meningitis (136.6 +/- 71.6, p < 0.01) and controls (181.3 +/- 88.3, p < 0.01). These findings suggest that TPO is not produced in the CNS of patients with meningitis and that TPO did not cross the blood-brain barrier even during meningeal infection.

Adolescent↗

PubMed2005

[Childhood acute lymphoblastic leukemia with t(1;19) lacking E2A-pBX1 chimeric transcripts].

We present a pediatric case of acute lymphoblastic leukemia (ALL) with chromosomal translocation 1;19 lacking E2A-PBX1 chimeric transcripts. On admission, the patient showed remarkable splenomegaly. Laboratory findings demonstrated that WBC was 12900/microl with blasts 61.5%. Bone marrow examination revealed 1282 X 10(3)/microl of the nucleated cell count with 95.5% lymphoblasts. Surface marker analysis showed an early pre-B lineage immunophenotype (CD10+, CD19+, CD34+, surface Ig-). Although G-banding chromosomal analysis showed 46,XY,der(19)t(1;19)(q23;p13), E2A-PBX1 chimeric transcripts and E2A gene rearrangement were not detected with the polymerase chain reaction method and Southern blot analysis, respectively. The patient was assigned to high-risk ALL according to the criteria of the Japan Association of Childhood Leukemia Study. His clinical response to prednisolone monotherapy for the initial 7 days and subsequent multidrug chemotherapy was excellent, and he achieved complete remission on day 15, which has lasted for more than 30 months. We reviewed the bibliography of the clinical and biological features of 17 children with t(1;19)+E2A-PBX1- ALL including this case. The two prominent characteristics included an early pre-B immunophenotype (11/13) and hyperdiploid (>50 chromosomes) chromosome abnormality (8/14). However, there was substantial heterogeneity in the demographic features and prognosis. Further accumulation of such patients will facilitate the determination of the appropriate treatment for childhood t(1;19)+E2A-PBX1- ALL.

Adolescent↗

PubMed2004

Age-dependent changes in the incidence and etiology of childhood thrombocytosis.

To determine the incidence and etiology of childhood thrombocytosis, over 15,000 platelet counts in 7,539 patients performed at a single regional hospital were reviewed. When thrombocytosis was defined as > or =500 x 10(9)/l of platelet counts, the condition could be diagnosed in 6.0% (456 cases) of the patients. All patients were classified as having secondary thrombocytosis. The incidence of thrombocytosis dramatically changed throughout child development; it was 12.5% in neonates, peaked to 35.8% in 1-month-old infants and then returned to 12.9% in 6- to 11-month-old infants. Thereafter, it gradually decreased with age to only 0.6% in 11- to 15-year-old children. Frequent causes of thrombocytosis included infection (67.5%), Kawasaki disease (9.4%), prematurity (7.7%) and iron deficiency anemia (6.4%). Thrombocytosis was an incidental finding in a substantial population of early infants. Thrombocytosis as a reaction to several types of infection and Kawasaki disease was more common in children under 7 years old, while autoimmune disease and tissue damage were major causes in children aged 11-15 years. No child had thromboembolic complications. These findings indicate that childhood thrombocytosis is a benign condition and its incidence and etiology seem to depend on age.

Adolescent↗

PubMedDate not supplied

Acute lymphoblastic leukemia with coexpression of CD56 and CD57: case report.

The authors present the clinical profile of a 6-year-old girl with an unusual immunophenotype of acute lymphoblastic leukemia (ALL). At the initial presentation, massive hepatosplenomegaly developed. The leukemic cells were myeloperoxidase-negative and morphologically lymphoblastic. These cells were positive for B-precursor-cell (CD10, CD19) antigens and natural killer cells (CD56, CD57). Rearrangements of both immunoglobulin heavy chain alleles and monoallelic rearrangement of T-cell receptors (TCRs)-beta and -delta genes, but not that of TCR-gamma gene, were detected, suggesting that these cells being of B-precursor origin. The patient received chemotherapy for extremely high-risk ALL with a good response. To the authors' knowledge, this is the first pediatric case describing coexpression of CD56 and CD57 on B-lineage ALL.

Antigens, CD↗