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Biomedical subjects

T Hiratsuka

Publications and source records attributed to T Hiratsuka.

At least 37 records · Page 2Linked to original sources
PubMed1999

Deletion of the myopathy loop of Dictyostelium myosin II and its impact on motor functions.

One of the putative actin-binding sites of Dictyostelium myosin II is the beta-strand-turn-beta-strand structure (Ile(398)-Leu-Ala-Gly-Arg-Asp(403)-Leu-Val(405)), the "myopathy loop, " which is located at the distal end of the upper 50-kDa subdomain and next to the conserved arginine (Arg(397)), whose mutation in human cardiac myosin results in familial hypertrophic cardiomyopathy. The myopathy loop contains the TEDS residue (Asp(403)), which is a target of the heavy-chain kinase in myosin I. Moreover, the loop contains a cluster of hydrophobic residues (Ile(398), Leu(399), Leu(404), and Val(405)), whose side chains are fully exposed to the solvent. In our study, the myopathy loop was deleted from Dictyostelium myosin II to investigate its functional roles. The mutation abolished hydrophobic interactions of actin and myosin in the strong binding state during the ATPase cycle. Association of the mutant myosin and actin was maintained only through ionic interactions under these conditions. Without strong hydrophobic interactions, the mutant myosin still exhibited motor functions, although at low levels. It is likely that the observed defects resulted mainly from a loss of the cluster of hydrophobic residues, since replacement of Asp(403) or Arg(402) with alanine generated a mutant with less severe or no defects compared with those of the deletion mutant.

Actins↗
PubMed1999

ATP-induced opposite changes in the local environments around Cys(697) (SH2) and Cys(707) (SH1) of the myosin motor domain revealed by the prodan fluorescence.

To obtain a consistent view of the nucleotide-induced conformational changes around Cys(697) (SH2) and Cys(707) (SH1) in skeletal myosin subfragment-1 (S-1), the two thiols were labeled with the same environmentally sensitive fluorophore, 6-acyl-2-dimethylaminonaphthalene group, using 6-acryloyl-2-dimethylaminonaphthalene (acrylodan, AD) and 6-bromoacetyl-2-dimethylaminonaphthalene (BD), respectively. The resultant fluorescent derivatives, AD-S-1 and BD-S-1, have the same fluorophore at either SH2 or SH1, which was verified by inspections of changes in the ATPases and the localization of fluorescence after tryptic digestion and CNBr cleavage for the two derivatives. Especially, AD was found to be a very useful fluorescent reagent that readily reacts with only SH2 of S-1. Measurements of the nucleotide-induced changes in fluorescence emission spectra of AD-S-1 and BD-S-1 suggested that during ATP hydrolysis the environment around the fluorophore at SH2 is very distinct from that around the fluorophore at SH1, being defined as that the former has the hydrophobic and closed characteristics, whereas the latter has the hydrophilic and open ones. The KI quenching study of the fluorescence of the two S-1 derivatives confirmed these results. The most straightforward interpretation for the present results is that during ATP hydrolysis, the helix containing SH2 is buried in hydrophobic side chains and rather reinforced, whereas the adjacent helix containing SH1 moves away from its stabilizing tertiary structural environment.

2-Naphthylamine↗
PubMed1999

[A study of human beta-defensin-1 and human beta-defensin-2 in airway mucosal defense].

Human beta-defensin-1 (hBD-1) and human beta-defensin-2 (hBD-2) are new members of the defensin family. In this study, we investigated their gene expressions in the respiratory epithelial surface of the human lung and their bactericidal activities against Escherichia coli. Both hBD-1 and hBD-2 gene transcripts were detected in human lung tissue and cellular component of bronchoalveolar lavage fluid by reverse transcription-polymerase chain reaction. Synthetic hBD-1 and hBD-2 had dose-dependent bactericidal activities against E. coli. The concentration for the 50% colony reduction of hBD-2 was 0.46 nmol/ml, that for HNP-1 2.15 nmol/ml, and hBD-1 99.3 nmol/ml under conditions nearly the same as in human bronchial airway surface liquid. We prepared an antiserum against hBD-2 and established a highly sensitive radioimmunoassay and quantified plasma hBD-2 concentrations in normal subjects and patients with pneumonia. The plasma concentration of hBD-2 in normal individuals was 8.3 +/- 0.9 fmol/ml (mean +/- SE). The mean hBD-2 plasma concentration for the 12 patients with bacterial pneumonia in the acute stage was 34.2 +/- 3.4 fmol/ml, significantly higher than normal individuals, and returned to the normal range after recovery. The presence of hBD-1 and hBD-2 in the airway tract and their bactericidal activity suggest that they function in innate airway mucosal defense.

Adult↗
PubMed1999

Association between HLA-DRB1*15 and Japanese patients with rheumatoid arthritis complicated by renal involvement.

We performed serological phenotyping of HLA antigens in 175 patients with rheumatoid arthritis (RA) with (n = 41) and without (n = 134) renal involvement (RI), and DNA typing of HLA class II alleles in 75 patients. Among the patients with RA, the frequency of serologically determined HLA-DR4 was found to be significantly increased (odds ratio: 1.8, confidence interval: 1.3-2.5, p = 2.4x10(-4)). In the patients without RI, the frequency of serological DR4 significantly increased (odds ratio: 2.2, confidence interval: 1.6-3.3, p = 2. 6x10(-5)). On the other hand, among the patients with RI, a serological determinant, DR15, did significantly increase (odds ratio: 2.7, confidence interval: 0.9-8.4, p = 1.2x10(-3)) in comparison to the controls. At the DNA level, we found that the association of Japanese RA patients with serological HLA-DR4 was based on that with a genotype of HLA-DRB1*0405 (odds ratio: 2.4, confidence interval: 1.5-4.0, p = 4.4x10(-4)) and also found an association of HLA-DRB1*1501 (odds ratio: 2.8, confidence interval: 1.2-6.6, p = 0.017) with RA patients having RI. Our results confirmed the association of HLA-DRB1*04 with RA over the ethnic barrier at the DNA level. Our results also suggested a distinct genetic effect of HLA-DRB1*1501 in the aspect of the susceptibility of RI in RA.

Aged↗
PubMed1999

An investigation of the relationship between duct system and A cell-rich and PP cell-rich pancreatic islets in the canine pancreas.

The pancreata of four six-month-old dogs of the same mother, two with both the pancreatic and accessory pancreatic ducts (X-type) and two with only the accessory pancreatic duct (Y-type), were examined in this study. To clarify the relationships between the type of pancreatic duct system and the composition of pancreatic endocrine cells, the pancreata were examined immunohistochemically using antiserum against four types of pancreatic hormones (glucagon, insulin, somatostatin and pancreatic polypeptide). In all areas of the X- and Y-type duct system pancreata, B cells accounted for 52-82% of the total number of islet cells, and D cells accounted for 4-15%. In the X-type ducts system, the percentages of A and PP cells in the right and left lobes of the pancreas differed greatly. It was found that A and PP cells appear in inverse proportion to each other and that there exist A cell-rich and PP cell-rich pancreatic islets. The A cell-rich pancreatic islets appeared in the left lobes along the accessory pancreatic duct, while the PP cell-rich pancreatic islets were observed in the right lobes along the pancreatic duct. The body of the pancreas contained both A cell-rich and PP cell-rich pancreatic islets. In the Y-type duct systems, A cell-rich pancreatic islets appeared in the right lobes. These findings indicate that the composition of A and PP cells in pancreatic islets is closely related to the type of duct system.

Animals↗
PubMed1998

Identification of human beta-defensin-2 in respiratory tract and plasma and its increase in bacterial pneumonia.

Human beta-defensin-2 (hBD-2), a novel antimicrobial peptide, was originally isolated from human skin. We found that synthetic hBD-2 has high bactericidal activity against Escherichia coli under conditions nearly the same as in human bronchial airway surface liquid. We prepared an antiserum against hBD-2 and established a highly sensitive radioimmunoassay (RIA). Reverse-phase high-performance liquid chromatography coupled with the RIA showed that hBD-2 in patients with human lung, bronchoalveolar lavage flid, and plasma. The plasma concentration of hBD-2 in patients with bacterial pneumonia was 32.1 +/- 3.7 fmol/ml (mean +/- SE), 3.9-fold that of normal individuals. By reverse transcription-polymerase chain reaction, the hBD-2 gene transcript was detected in the respiratory epithelial surface of human lung. Human beta-defensin-2 seems to function in airway mucosal defense. Our findings provide a clue to elucidate its pathophysiological significance in respiratory infection.

Adult↗
PubMed1998

Prodan fluorescence reflects differences in nucleotide-induced conformational states in the myosin head and allows continuous visualization of the ATPase reactions.

The noncovalent fluorescent probe 6-propionyl-2-(dimethylamino)naphthalene (prodan) binds stoichiometrically to myosin subfragment-1 (S-1) without affecting the ATPase and actin-binding properties of S-1. Neither ATP nor actin interferes with the prodan binding. Free prodan exhibits a green emission peak at 520 nm. However, the prodan bound to S-1 and the S-1.ADP complex shows blue emission peaks at 460 and 450 nm, respectively, which allow easy separation of the fluorescence contributions from the free and bound probes. In the S-1.ADP.Pi state, the blue emission peak is further shifted to 445 nm with a large (4.5-fold) fluorescence enhancement. Thus, prodan in the presence of S-1 exhibits predominantly blue fluorescence only during ATP hydrolysis, and so visualizes the ATPase reaction continuously. The initial velocities of the steady state of the Mg2+-, Ca2+-, and actin-activated ATPases can be conveniently calculated from the blue fluorescence changes. The ability of different nucleoside triphosphates (NTP) to enhance the blue fluorescence of prodan follows the order ATP > CTP > UTP > ITP > GTP. This order agrees with those of the extent of hydrophobicity near the ribose of the corresponding nucleoside diphosphates (NDP) trapped to S-1 with orthovanadate (Vi) [Hiratsuka, T. (1984) J. Biochem. (Tokyo) 96, 155-162] and the ability of different NTPs to support force production in muscle fibers [Regnier, M., et al. (1993) Biophys. J. 64, A250]. The rate of formation of the corresponding S-1.NDP.Vi complex also follows this order, whereas the NTPase rate follows the reverse order. These results indicate that nucleotide-induced changes in prodan fluorescence correspond to the nucleotide-induced conformational states of S-1. Thus, the use of prodan in studies of the myosin ATPase offers a new and promising approach not only to monitoring the ATPase reaction but also to investigating the structural changes during ATP hydrolysis.

2-Naphthylamine↗
PubMed1998

[Severe bronchorrhea accompanying alveolar cell carcinoma: treatment with clarithromycin and inhaled beclomethasone].

We report the efficacy of oral clarithromycin and inhaled beclomethasone against severe bronchorrhea in a patient with alveolar cell carcinoma. A 54-year-old man produced about 500 to 900 ml of clear and egg-white-like sputum each day. Anti-cancer chemotherapy and erythromycin therapy did not reduce the volume of sputum. After administration of clarithromycin and inhaled beclomethasone, sputum volume decreased to about 300 nl each day and the patient's ability to perform daily activities improved. Two months later, clarithromycin was stopped and the patient was treated with inhaled beclomethasone alone. Sputum volume did not increase for 6 months, although the chestroentgenographic findings gradually worsened. Then the sputum volume gradually increased. Five months after the sputum volume began to increase, he was producing about 2 liters of sputum each day and died of respiratory failure. Although the levels of CA 19-9, SLX, and CEA in serum were all within the normal range, the sputum contained high levels of CA 19-9 (1,133,620 U/ml), SLX (3,000 U/ml), and CEA (283 ng/ml). In patients with bronchorrhea, measurement of tumor markers in sputum may be useful for the diagnosis of alveolar cell carcinoma.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1997

Monitoring the myosin ATPase reaction using a sensitive fluorescent probe: pyrene-labeled ATP.

A pyrene-labeled ATP (Pyr-ATP) in which a pyrene fluorophore is linked to the ribose moiety of ATP with a butyryl chain has been synthesized, together with the corresponding analog of ADP. The spectroscopic properties of two fluorescent analogs were found to be similar to those of 1-pyrenebutyric acid, making them photostable and highly sensitive probes for detecting changes in conformations around the nucleotide binding sites of proteins. Binding of Pyr-ADP to myosin subfragment-1 (S-1) resulted in a fluorescence quenching of about 70%. This binding was tight, with a dissociation constant (0.9 microM) similar to that of ADP itself. Formation of the stable ternary complex of Pyr-ADP with S-1 and orthovanadate could be monitored from the quench in pyrene fluorescence with a rate constant of 0.01 s-1. The final fluorescence intensity was about 20% of that for Pyr-ADP alone. Pyr-ATP was hydrolyzed by S-1 1.3 times faster than was ATP. Hydrolysis of Pyr-ATP was accompanied by an initial quenching of pyrene fluorescence with a subsequent recovery of the fluorescence. The fluorescence changes could be used to monitor the hydrolysis reaction continuously and measure the turnover rates of the analog. The fluorescence assay was sensitive, particularly under single turnover conditions, allowing hydrolysis reactions to be monitored at concentrations of S-1 and the analog as low as 50 nM.

Adenosine Diphosphate↗
PubMed1997

Morphological study of bovine pregnant corpus luteum cells.

The bovine pregnant corpus luteum was examined morphologically, to clarify the appearance and properties of the intramitochondrial bodies (IMB) in mitochondria of the large luteum cell (LLC). The incidence and diameter of the IMB (200-900 nm) showed a tendency to increase with the advance of pregnancy. Histochemically, the IMB reacted positively with protein, and immunohistochemically, they reacted IMB with 11 alpha-hydroxyprogesterone-1-11 succinyl-bovine serum albumin (P-BSA). The IMB seemed to combine with protein, and these granules did not undergo exocytosis. The cytoplasm of LLC contained another type of small electron-dense granules that were 150-200 nm in diameter, had an orifice for secretion, and reacted with relaxin. Small luteum cells (SLC) revealed crystalline-like inclusions. It is suggested that these inclusion cells participate in the synthesis of steroids.

Animals↗
PubMed1997

[Serum-soluble adhesion molecules in patients with idiopathic pulmonary fibrosis and acute respiratory distress syndrome].

We measured the concentrations of soluble adhesion molecules in serum obtained from healthy volunteers and from patients with idiopathic pulmonary fibrosis (IPF) and the acute respiratory distress syndrome (ARDS). The concentrations of soluble intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), E-selectin, and P-selectin were significantly higher in serum from the patients than in serum from the healthy volunteers. In patients with IPF, the concentration of soluble ICAM-1 in serum was inversely related to the vital capacity (expressed as a percent of the predicted value). The concentrations of L-selectin in serum from patients with ARDS were significantly lower than those in serum from healthy volunteers and from patients with IPF. These data suggest that serum-soluble adhesion molecules may be useful as markers of disease activity, severity, and prognosis in ARDS and IPF.

Aged↗
PubMed1996

Immunohistochemical analysis of the endocrine cells in the pancreatic islets of cattle.

The distribution of endocrine cells and the areas of islets in the bovine pancreas were investigated by immunohistochemical methods. The islets in the A-region, which consisted of the left lobe, the ventral portion of the body, and the ventral and distal portions of the right lobe, contained a central core of insulin-containing (B-) cells surrounded by glucagon containing (A-) cells, a few somatostatin-containing (D-) cells and sporadic pancreatic polypeptide-containing (PP-) cells. The islets in the B-region, which consisted of the uncinate process, and the dorsal and proximal portions of the body and the right lobe, contained a central mass of B-cells, and peripheral cells which were predominantly PP-cells with a few D-cells but no A-cells. The areas of islets in the B-region were small as compared with those in the A-region. From these findings it is suggested that A- and PP-cells have a complementary relationship to one another. In view of this hypothesis, two types of islet, A-cell-rich and PP-cell-rich islets, were identified. The A-region contained A-cell-rich islets derived from the dorsal pancreatic primordium, while the B-region contained PP-cell-rich islets that originated from the ventral primordium. In the bovine pancreas, the areas containing PP-cell-rich islets are greater than those in previously examined species.

Animals↗
PubMed1995

Association of DQB1*0302 alloantigens in Japanese pediatric patients with steroid-sensitive nephrotic syndrome.

We identified human leukocyte alloantigens (HLA) class II alleles in 24 Japanese children with steroid-sensitive nephrotic syndrome (SSNS) by deoxyribonucleic acid (DNA) typing. The DQA1 and DQB1 alleles were identified using sequence-specific oligonucleotide probes for DQA and DQB. The frequency of DQB1*0302 was significantly higher in the patients than in the controls (54.0 vs. 16.0%, respectively; relative risk, RR = 6.2; pc < 0.00009. We also found that the frequency of DQA1*0103 in the patients was significantly lower than in the controls (RR = 0.194, pc < 0.04). Several studies have identified an association between certain HLA by serotyping. In the present study, we investigated the HLAs of Japanese patients with SSNS by DNA typing and observed a significant increase in the frequency of DQB1*0302 in patients with the disease. HLA-DQ3, which was proven to be associated with SSNS, consists of HLA DQ7, 8 and 9. DQB1*0302 is a component of HLA-DQ8. So we proposed the increase of DQ3 was due to an increase in DQ8.

Adolescent↗
PubMed1995

Fine structure of podocytes in the bovine renal corpuscle.

Thick primary processes issued from the hemispherical or plate-like cell bodies of podocytes in bovine renal corpuscles. These processes branched into secondary and tertiary ones, but no fine pedicels were observed on the outer surface of the podocytes by scanning electron microscopy, because each primary process closely interdigitated with those of adjacent cells. Many pedicels, however, were observed under the processes by using the freeze-fractograph and a transmission electron microscope.

Aging↗
PubMed1995

Microvascular changes in the bovine corpus luteum during pregnancy.

The microvasculature of bovine corpora lutea during pregnancy was studied by scanning electron microscopy using corrosion casts. Only one spiral arteriole branched directly from the ovarian artery entered the blood vascular bed of the pregnant corpora lutea. The bed consisted of numerous lobular sinusoidal capillary plexuses during pregnancy, and were characteristic to the microvasculature of a large corpus luteum. At the late stage of pregnancy, arteriovenous anastomoses were situated within the lobular sinusoidal capillary plexus composed of thin sinusoidal capillaries. These anastomoses may induce a decrease in blood flow to the lobular sinusoidal capillary plexus, suggesting that they may have an important role to induce the initial degeneration of the bovine pregnant corpora lutea.

Animals↗