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Biomedical subjects

T Matsuda

Publications and source records attributed to T Matsuda.

At least 181 records · Page 10Linked to original sources
PubMed2000

Detailed motion analysis of the left ventricular myocardium using an MR tagging method with a dense grid.

Detailed analysis of myocardial deformation through a whole cardiac cycle was accomplished using a tagging method with a high-density grid. Four sets of tagged images with a 4-mm-spacing grid were measured by generating four tagging pulses arranged at regular intervals in the cardiac cycle. Through each set of images, tag intersections were tracked semi-automatically. The estimated motions of tag intersections were concatenated so that sequential positions of myocardium were connected through a whole cardiac cycle. In vitro evaluation of the precision of this technique showed that the mean error of tracked 4-mm tag intersections was less than 0.47 +/- 0.17 mm, even on the quite low-contrast images, and the concatenation error caused by double concatenation was comparable to the interpolation error in the subendocardial area obtained with 8-mm tag intersection motion. The small difference between the two mean distance curves of the in vivo evaluation indicated that the method is useful for analyzing heart wall abnormalities. Magn Reson Med 44:73-82, 2000.

Algorithms↗
PubMed2000

Semi-quantitative approach to estimating GFR by magnetic resonance imaging.

OBJECTIVE: The purpose of this study was to compare a semi-quantitative approach to estimating glomerular filtration rate (GFR) by magnetic resonance imaging with radionuclide calculation of GFR, and to investigate whether spin echo or gradient echo is more suitable for estimating GFR. METHODS AND PATIENTS: Fourteen kidneys of seven patients (GFR ranging from 26 to 57 ml/min) were studied. Spin echo and gradient echo sequences interleaving each other at every excitation were used. After intravenous injection of gadopentetate dimeglumine, serial scans were performed. The signal intensities measured in the regions of interest were converted to time-transverse relaxation rate changes for both spin echo (DeltaR2) and gradient echo (DeltaR2*). The areas under the time-DeltaR2 and time-DeltaR2* curves were calculated as a semi-quantitative index of GFR for both spin echo and gradient echo images, and the results were compared by GFR measured by radionuclide imaging. RESULTS: The semi-quantitative index of the GFR calculated from spin echo images showed a significant correlation with the GFR measured by radionuclide imaging (r=0.85, P<0.001). On the other hand, the semi-quantitative index of the GFR calculated from gradient echo images showed no such correlation (r=0.46, P=0.10). CONCLUSION: Spin echo sequences may be more suitable than gradient echo sequences for the evaluation of GFR.

Adult↗
PubMed2000

Significant regional heterogeneity of coronary flow reserve in paediatric hypertrophic cardiomyopathy.

Previous studies have indicated that cardiac events in young patients with hypertrophic cardiomyopathy (HCM) are related to ischaemia rather than to arrhythmia. We measured coronary flow reserve in paediatric HCM and compared the values with those in adult HCM. We studied 12 patients with HCM including six paediatric (<20 years old; mean 13 years) and six adult patients (>20 years old: mean 62 years), and six healthy young adults (mean 29 years) as controls. Every patient underwent magnetic resonance imaging (MRI) for anatomical assessment. Myocardial blood flow at rest and after dipyridamole infusion was measured with dynamic nitrogen-13 ammonia positron emission tomography (PET). Partial volume effect was corrected for using the anatomical data obtained with MRI. In adult patients with HCM, coronary flow reserve in the hypertrophied septal region was not significantly different from that in the non-hypertrophied lateral wall (1.38+/-0.29 vs 1.77+/-0.39, respectively). In the paediatric patients, coronary flow reserve in the hypertrophied septal region was significantly lower than in the non-hypertrophied lateral wall (0.84+/-0.33 vs 2.74+/-0.90, respectively, P<0.01). In addition, coronary flow reserve in adult patients was lower than in control subjects both in the septal wall (1.38+/-0.29 vs 2.94+/-0.35, respectively, P<0.0001) and in the lateral wall (1.77+/-0.39 vs 2.85+/-0.69, respectively, P<0.05). In contrast, coronary flow reserve in paediatric patients was not significantly different from that in control subjects in the lateral wall (2.74+/-0.90 vs 2.85+/-0.69, respectively), while absolute reduction of myocardial blood flow was noted after pharmacological vasodilatation in the hypertrophied septal region. In conclusion, significant regional differences of coronary flow reserve were present in the paediatric patients with HCM. These results suggest that paediatric patients with HCM intrinsically have the potential to experience significant regional ischaemia even in the absence of coronary stenosis.

Adolescent↗
PubMed2000

Future of urologic laparoscopy.

Laparoscopy has become increasingly popular in urology, reducing the invasiveness of treatment and shortening the period of convalescence. Adrenalectomy is one of the procedures most widely accepted for urologic laparoscopy. During the twenty-first century, most urologic operations will likely be performed laparoscopically, benefiting from advancements in medical engineering. The development of new tissue approximation methods, tissue retrieval systems, microlaparoscopic instruments, sensor technology, and telerobotics, as well as virtual reality, will contribute to the establishment of safe, easy laparoscopic urologic surgery.

Humans↗
PubMed2000

Successful treatment of B-cell lymphoma associated with hemophagocytic syndrome using autologous peripheral blood CD34 positive cell transplantation followed by induction of autologous graft-versus-host disease.

A 56-year-old man who presented with persistent high fever and abdominal pain was diagnosed as having a B-cell lymphoma associated with hemophagocytic syndrome (B-LAHS). As post-remission therapy, the patient was treated with high-dose chemoradiotherapy followed by infusion of autologous CD34+ cells that had been isolated from the peripheral blood buffy coat. Cyclosporin and interferon (IFN)-gamma were administered to induce autologous graft-versus-host disease (GVHD). Hematopoietic recovery promptly occurred and skin GVHD developed on day 26 after CD34+ cell transplantation. The patient has been in complete remission without therapy for 20 months since transplant. Autologous CD34+ cell transplantation in combination with induction of autologous GVHD may be efficacious in obtaining a cure for B-LAHS.

Antigens, CD34↗
PubMed2000

Decreased expression of mouse Rbm3, a cold-shock protein, in Sertoli cells of cryptorchid testis.

Physiological scrotal hypothermia is necessary for normal spermatogenesis and fertility in mammals. Human RNA binding motif protein 3 (RBM3) is structurally highly similar to the cold-inducible RNA-binding protein (Cirp), and both mRNAs are induced in human cells at the scrotal temperature (32 degrees C). We report here the cloning of mouse Rbm3 cDNA, which encoded an 18-kd protein with 94% identity in amino acid sequence to that of human RBM3. In the testis of adult mice, Rbm3 mRNA and protein were detected in Sertoli cells, but not germ cells, of seminiferous tubules at all stages. The expression was not observed in Sertoli cells of fetuses, but was observed in newborn and older mice. In the TAMA26 mouse Sertoli cell line, the Rbm3 expression level was increased or decreased within 12 hours after temperature shift from 37 degrees C to 32 degrees C or 39 degrees C, respectively. In contrast to Cirp, the cold-induced growth suppression of TAMA26 cells was not affected by suppression of the Rbm3 expression. When mouse testis was exposed to heat stress by experimental cryptorchidism, the level of Rbm3 was decreased in Sertoli cells. Rbm3 may play important roles distinct from those played by Cirp in spermatogenesis and cryptorchidism by regulating the gene expression in Sertoli cells.

Amino Acid Sequence↗
PubMed2000

Possible requirement of phosphonate moiety for efonidipine effects on the sino-atrial node action potential.

The effects of efonidipine, a 1,4-dihydropyridine phosphonate, and structurally related compounds on rabbit sino-atrial node action potential were examined with microelectrodes. 3NIC5NZ has a phosphonate moiety identical to that of efonidipine at the C5 position of the dihydropyridine ring and a side chain identical to nicardipine at C3, while 3NZ5NIC has C5 and C3 side chains identical to nicardipine and efonidipine, respectively. All four compounds decreased the slope and prolonged the early and late phases of pacemaker depolarization. The selectivity for the late phase against the early phase was in the order of efonidipine > 3NIC5NZ >> nicardipine > 3NZ5NIC. Thus, the phosphonate moiety at C5 position of the may be important for the characteristic prolongation of the late phase pacemaker depolarization by efonidipine.

Action Potentials↗
PubMed2000

No involvement of lipid mediators in a guinea pig model of ultrasonically nebulized distilled water-induced bronchoconstriction.

An inhalation of ultrasonically nebulized distilled water (UNDW) induces bronchoconstriction only in asthmatics, but the mechanism underlying the response is not fully understood. We have reported that bronchoconstriction occurs immediately after UNDW is inhaled 20 min after an antigen challenge in guinea pigs. Our aim was to examine the role of lipid mediators in this response. Passively sensitized guinea pigs were anesthetized and artificially ventilated. A sulfidopeptide leukotriene receptor antagonist, KCA-757, and platelet-activating factor antagonists, Y-24180 and E6123, were administered i.v. 15 min after an aerosolized antigen challenge, and UNDW was inhaled 5 min later. KCA-757, Y-24180, or E6123 did not, significantly alter the UNDW-induced bronchoconstriction. Together with our previous data that thromboxane A2 receptor antagonists did not influence the UNDW-induced bronchoconstriction, the present results suggest that lipid mediators are not involved in the UNDW-induced bronchoconstriction in our guinea pig model.

Animals↗
PubMed2000

Introduction of a specific binding domain on myoglobin surface by new chemical modification.

A new myoglobin, reconstituted with a modified zinc protoporphyrin, having a total of four ammonium groups at the terminal of the two propionate side chains was constructed to introduce a substrate binding site. The protein with a positively charged patch on the surface formed a stable complex with negatively charged substrates, such as hexacyanoferrate(III) and anthraquinonesulfonate via an electrostatic interaction. The complexation was monitored by fluorescence quenching due to singlet electron transfer from the photoexcited reconstituted zinc myoglobin to the substrates. The binding properties were evaluated by Stern-Volmer plots from the fluorescence quenching of the zinc myoglobin by a quencher. Particularly, anthraquinone-2,7-disulfonic acid showed a high affinity with a binding constant of 1.5 x 10(5) M(-1) in 10 mM phosphate buffer, pH 7.0. In contrast, the plots upon the addition of anthraquinone-2-sulfonic acid at different ionic strengths indicated that the complex was formed not only by an electrostatic interaction but also by a hydrophobic contact. The findings from the fluorescence studies conclude that the present system is a useful model for discussion of electron transfer via non-covalently linked donor-acceptor pairing on the protein surface.

Anthraquinones↗
PubMed2000

Transient treatments with L-glutamate and threo-beta-hydroxyaspartate induce swelling of rat cultured astrocytes.

We characterized swelling of rat cultured astrocytes induced by L-glutamate and its analogues. Among L-glutamate receptor agonists, L-glutamate, L-aspartate, L-cysteic acid, DL-homocysteic acid, quisqualate and (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) increased astrocytic intracellular volume (3H-OMG space), while kainate, and N-methyl-D-aspartate did not. Threo-beta-hydroxyaspartate (TBHA), D-aspartate and L-trans-pyrrolidine-2,4-dicarboxylic acid, high-affinity substrates for Na+-dependent L-glutamate transporters, increased astrocytic 3H-OMG space. L-Glutamate (0.5 mM) increased astrocytic 3H-OMG space to 300% of control in 40-60 min. The increase in 3H-OMG space by 1 mM TBHA was comparable to the L-glutamate-induced one. After a 10 min-exposure to 0.5 mM L-glutamate, astrocytic 3H-OMG space was further increased to 200% even in the absence of L-glutamate. Astrocytes transiently exposed to L-glutamate did not increase their cell volume in K+-free medium and in the presence of 1 mM ouabain, a Na+-K+ ATPase inhibitor. The increase after a transient exposure was also observed by a treatment of 1 mM TBHA, but not by 0.5 mM quisqualate. These results suggest that the volume increases after a transient treatment are mediated by activation of Na+-dependent L-glutamate transporter.

3-O-Methylglucose↗
PubMed2000

Endothelins increase tyrosine phosphorylation of astrocytic focal adhesion kinase and paxillin accompanied by their association with cytoskeletal components.

Astrocytic endothelin receptors are involved in the appearance of activated astrocytes upon injury of the brain [Ishikawa N. et al. (1997) Eur. J. Neurosci. 9, 895-901; Koyama Y. et al. (1999) Glia 26, 268-271]. To clarify signal transduction triggered by endothelin receptors, we examined the effects of endothelins on protein tyrosine phosphorylation in cultured rat astrocytes. Endothelin-1 (1 nM) increased tyrosine phosphorylation of focal adhesion kinase and paxillin. The tyrosine phosphorylation was also induced by endothelin-1 (1 nM) and Ala(1,3,11,15)-endothelin-1 (10nM), an endothelin-B receptor agonist. BQ788 (100 nM), an endothelin-B receptor antagonist, inhibited the effects of endothelin-3. Orthovanadate (VO(4)(3-)), a tyrosine phosphatase inhibitor, but not bradykinin (1 microM), angiotensin II (100 nM), A23187 (5 microM) and phorbol 12-myristate 13-acetate (100 nM), increased tyrosine phosphorylation of focal adhesion kinase and paxillin. The tyrosine phosphorylation by endothelin-3 was not prevented by pertussis toxin, Ca(2+) chelation, protein kinase C inhibitors (calphostin C and staurosporine) or wortmannin. Immunocytochemical staining showed that endothelin-3 and VO(4)(3-) induced redistribution of focal adhesion kinase and paxillin to focal adhesions concomitant with stress fiber formation in dibutyryl cyclic-AMP-treated astrocytes. Treatment with endothelin-3 and VO(4)(3-) increased focal adhesion kinase and paxillin associated with astrocytic cytoskeletal fraction. In the presence of cytochalasin B, an actin disrupting agent, endothelin-3 and VO(4)(3-) did not phosphorylate focal adhesion kinase and paxillin. Application of cytochalasin B after treatment with endothelin-3 and VO(4)(3-) stimulated dephosphorylation of focal adhesion kinase and paxillin. These results suggest that the associations of focal adhesion kinase and paxillin with cytoskeletal components are required in the endothelin-induced tyrosine phosphorylation of the astrocytic proteins.

Androstadienes↗
PubMed2000

Transperitoneal anterior laparoscopic adrenalectomy: the easiest technique.

Four laparoscopic methods have been developed to approach the adrenal gland: anterior or lateral transperitoneal approaches, and lateral or posterior retroperitoneal approaches. The advantages and disadvantages of these methods were reviewed during a workshop held by the Japanese Society of Endourology and ESWL in 1997. The transperitoneal anterior approach, when combined with a lateral approach for the left side, is the easiest for small adrenal tumors, and discloses the adrenal vein early in the procedure. For large tumors over 5 cm in diameter, the transperitoneal lateral approach is the most feasible bilaterally. Regardless of the methods of approach, laparoscopic adrenalectomy has already become the standard procedure for adrenal tumors, because it minimizes the operative morbidity and postoperative hospital stay.

Adrenalectomy↗
PubMed2000

Complications of laparoscopic and retroperitoneoscopic adrenalectomies in 370 cases in Japan: a multi-institutional study.

A total of 370 laparoscopic adrenalectomies, including 311 transperitoneal (TP) and 59 retroperitoneal (RP) approaches, were performed in nine urologic centers, where the laparoscopic adrenalectomy was first begun independently in Japan, and their affiliated hospitals between January 1992 and September 1996. The clinical diagnoses of those 370 adrenal diseases were primary aldosteronism in 155 patients, Cushing's syndrome in 61. preclinical Cushing's syndrome in 21. pheochromocytoma in 16, nonfunctioning adenoma in 87, complicated cyst in ten, myelolipoma in nine, adrenal cancer in four and other diagnoses in eight (table 1). There was no mortality in this series. Intraoperative complication rate was 33/370 (9%) in total: 26/311(8%) in the TP procedures and 7/59 (12%) in the RP procedures (table 11). Postoperative complication rate was 24/370 (6%) in total: 22/311 (7%) in the TP procedures and 2/59 (3%) in the RP ones (table 111). Conversion rates to open surgery in total, in the TP and in the RP procedures were 13/370 (3.5%), 10/311 (3.2%) and 3/59 (5.1 %). respectively (table IV). Although the RP procedure has a lower morbidity rate compared to the TP procedure, more skill is required to overcome the drawback of the narrow working space and fewer anatomical landmarks.

Adenoma↗
PubMed2000

Hemodynamic responses to photic stimulation in neonates.

A three-channel near-infrared monitoring system was used to evaluate the regional hemodynamic responses to photic stimulation during spontaneous sleep in seven healthy neonates. Three pairs of parallel light guides, separated by 15 mm each, were placed over a 450-mm(2) occipital region of the head. Increases in oxygenated and total hemoglobin were observed during photic stimulation only in one channel, and no change or decreases in oxygenated, deoxygenated, and total hemoglobin were observed in the other two channels. The change in the direction of deoxygenated hemoglobin accompanying the increases in oxygenated and total hemoglobin (usually a decrease in adults) differed in each subject and also varied with each measurement even in the same subject. An increase, decrease, and no change were observed. The results imply that an increase in regional cerebral blood flow occurs because of stimulation specific to the visual cortex and that the increase in deoxygenated hemoglobin observed in the visual cortex of the neonatal brain is attributable to venous dilation.

Cerebrovascular Circulation↗
PubMed2000

Supplemental glutamine augments phagocytosis and reactive oxygen intermediate production by neutrophils and monocytes from postoperative patients in vitro.

The energy substrate for neutrophils has been believed to be glucose. However, a recent investigation has demonstrated that neutrophils use glutamine (Gln) as well as glucose. Nevertheless, little is known about the effects of Gln on neutrophil function. Thus, this study was designed to investigate the effects of Gln on phagocytosis and reactive oxygen intermediate (ROI) production by neutrophils from postoperative patients in vitro. Eleven patients who had undergone major gastrointestinal surgery were randomly selected. Peripheral blood was drawn before surgery and on postoperative days (PODs) 1, 3, and 7. The blood was washed with medium to remove plasma. Washed whole blood was incubated in RPMI 1640 medium containing neither Gln nor glucose for 24 h at 37 degrees C. The medium was supplemented with Gln at a concentration of 0, 500, 1000, or 2000 microM. Whole blood was then assessed for phagocytosis by flow cytometry using fluorescent beads. ROI production by phagocytes was measured by flow cytometry using dihydrorhodamine 123. In each assay, the neutrophil population was gated and analyzed. Serum amino acids were also measured. Postoperative serum Gln level decreased significantly until POD 7. Phagocytosis by neutrophils on PODs 3 and 7 was significantly greater at 2000 microM Gln than at other Gln concentrations. Neutrophil ROI production was significantly greater at 2000 microM Gln than at 0 microM Gln at each time point. In conclusion, supplemental Gln enhances both phagocytosis and ROI production by neutrophils from postoperative patients in vitro.

Aged↗
PubMed2000

Tyk2 plays a restricted role in IFN alpha signaling, although it is required for IL-12-mediated T cell function.

Janus kinases (Jaks) play an important role in signal transduction via cytokine receptors. Tyk2 is a Janus kinase, and we developed tyk2-deficient mice to study the requirement for tyk2 in vivo. Tyk2-deficient mice show no overt developmental abnormalities; however, they display a lack of responsiveness to a small amount of IFNalpha, although a high concentration of IFNalpha can fully transduce its signal even in the absence of tyk2. Furthermore, IL-12-induced T cell function is defective in these mice. In contrast, these mice respond normally to IL-6 and IL-10, both of which activate tyk2 in vitro. These observations demonstrate that tyk2 plays only a restricted role in mediating IFNalpha-dependent signaling while being required in mediating IL-12-dependent biological responses.

Animals↗
PubMed2000

Hepatitis viral infection in Behçet's disease.

To elucidate the role of hepatitis viruses in the pathogenesis of Behçet's disease (BD), we measured hepatitis viral markers (anti-hepatitis A (anti-HA), HBsAg, anti-HBs, anti-HBc) and viral nucleic acids (hepatitis B virus (HBV)-DNA, hepatitis C virus (HCV)-RNA, GB virus C (GBV-C)-RNA, TT virus (TTV)-DNA) in the sera of 68 BD patients along with 76 blood donors matched for age and sex. Positivity of anti-HA in patients with BD (36.8%) was lower than that in blood donors (68.0%). Both anti-HCV and HCV-RNA were detected in only one (1.5%) patient with BD and in none of the blood donors. The prevalence ratios of HBsAg, anti-HBs, anti-HBc in both groups were similar (2.9:0, 16.2:15.8 and 17.7:19.7%, respectively). However, serum HBV-DNA was detected more frequently in BD patients (8/68; 11.8%) than in blood donors (2/76; 2.6%) (P<0.05). The prevalence of GBV-C-RNA was also higher in patients with BD (4/68; 5.9%) compared with blood donors (0%). However, characteristics and clinical features are similar between GBV-C-RNA-positive and -negative groups. With respect to the prevalence of TTV-DNA, there was no significant difference between BD patients (23.5%) and blood donors (30.3%). Our study indicates that HBV and GBV-C infection might be related to BD, although the role of these viruses remains to be investigated.

Journal Article↗