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Biomedical subjects

T Matsuda

Publications and source records attributed to T Matsuda.

At least 757 records · Page 42Linked to original sources
PubMed1994

Circular dichroism of metaiodopsin II and its binding to transducin: a comparative study between meta II intermediates of iodopsin and rhodopsin.

Through low-temperature absorption and circular dichroism (CD) spectroscopies, and G-protein (transducin) binding experiments, we have investigated molecular properties of the meta II intermediate of iodopsin, a cone visual pigment present in chicken red-sensitive cones. The meta II intermediate of iodopsin (metaiodopsin II, lambda max = 390 nm) displayed a positive CD band at about 390 nm and a large negative CD band below 300 nm. It dissociated into all-trans-retinal and the protein moiety. A long-lived intermediate corresponding to the meta III intermediate of rhodopsin was not observed in iodopsin, under our experimental conditions. Decay of metaiodopsin II was significantly suppressed in the presence of transducin, but not in the presence of both transducin and GTP, indicating that metaiodopsin II can interact with transducin and activate it. Both metaiodopsin II and metarhodopsin II displayed a large negative CD band below 300 nm. This fact suggested that during the formation of both meta II intermediates, some aromatic amino acid residues and/or a disulfide bond are rearranged, which may be important for expression of catalytic activity for exchange of GDP to GTP on transducin. On the other hand, metaiodopsin II decayed more than 10 times faster than metarhodopsin II. This fact may be one of the reasons why cones are less photosensitive than rods.

Animals↗
PubMed1994

Corticotropin-releasing factor stimulates Ca2+ influx in cultured rat astrocytes.

Corticotropin-releasing factor (CRF) increased intracellular Ca2+ concentration in single astrocytes. The effect in increasing intracellular Ca2+ was not observed in Ca2(+)-free solution. Furthermore, CRF at concentrations more than 10 nM stimulated 45Ca2+ uptake in cultured rat astrocytes. The action was blocked by alpha-helical CRF(9-41) in a competitive manner, but not by nifedipine and 3,4-dichlorobenzamil. On the other hand, CRF did not stimulate cAMP formation, cGMP formation and phosphoinositide hydrolysis in astrocytes. These results indicate that CRF increases Ca2+ influx via an activation of CRF receptors in a cAMP-independent mechanism in cultured astrocytes.

1-Methyl-3-isobutylxanthine↗
PubMed1994

[Radiotherapy for advanced carcinoma of the gallbladder: special reference to IORT and hyperthermo-chemo-radiotherapy].

The results of radiotherapy in 37 patients who were treated for carcinoma of the gallbladder from April 1975 to April 1992 are presented. To analyze the treatment results, patients were divided into four groups depending on treatment modality: intraoperative radiotherapy (IORT) with surgical resection in 9 (resection group), IORT with palliative surgery in 5 (palliative surgery group), hyperthermo-chemo-radiotherapy for inoperable cases in 11 (HCR group), external irradiation for inoperable cases in 12 (ExRT alone group). Most of the patients in the resection group received ExRT. The HCR group showed better local response than the groups treated with palliative surgery and ExRT alone. The mean length of survival in the resection, palliative surgery, HCR and ExRT alone groups was 315 days, 144 days, 246 days and 74 days, respectively. Although no statistically significant difference in survival was observed between the resection and HCR groups, the relapse-free interval of the resection group was significantly longer than that of the other groups. The application of IORT for surgically resectable tumors contributed to improved prognosis and better quality of life. Although IORT for patients with unresectable tumors had little effect on survival, it was considered to play a palliative role in improving the quality of life. The HCR group had a significantly longer survival time and relapse-free interval than the palliative surgery and ExRT alone groups. In conclusion, the application of HCR for inoperable carcinoma of the gallbladder contributed to the improvement of prognosis and quality of life.

Adult↗
PubMed1994

Effects of carboxyl methylation of photoreceptor G protein gamma-subunit in visual transduction.

G protein gamma-subunits are isoprenylated and carboxyl-methylated at the C-terminal cysteine, which is indispensable for the function of photoreceptor G protein transducin (T alpha beta gamma). However, the physiological role of the methylation and its reversibility have been unclear. Here we isolated methylated and non-methylated forms of farnesylated T beta gamma, and demonstrated that the methylation remarkably facilitates not only the membrane association of T beta gamma but also the subunit interaction between T alpha and T beta gamma. Consequently, the functional coupling of transducin with light-activated receptor, metarhodopsin II, was stabilized by the methylation, resulting in acceleration of GTP gamma S (guanosine 5'-3-O-(thio) triphosphate) binding to T alpha. An examination of the reversibility of the methylation suggested that T gamma is kept fully methylated in rod outer segments. These observations indicate that the methylation of T gamma plays an important role in the most efficient photon-signal transduction process in rod cells.

Adenosine Diphosphate Ribose↗
PubMed1994

Production and characterization of monoclonal antibodies directed against bovine milk fat globule membrane (MFGM).

Nine hybridomas secreting monoclonal antibodies (mAbs) to bovine milk fat globule membrane (MFGM) were produced from spleen cells of three immunized BALB/c mice. Several MFGM antigens recognized by some mAbs were identified as a 120 kDa protein and 67 kDa (butyrophilin), 57 kDa (PAS-6), 53 kDa (PAS-7), 33 kDa glycoproteins. The other mAbs secreted by four independent hybridoma clones recognized many broad bands ranging from 20 to 200 kDa. The 120 kDa protein and 67 kDa, 57 kDa, 53 kDa glycoproteins were detected by each mAb in the plasma membrane fraction prepared from a lactating bovine mammary gland. Moreover, mammary gland epithelium of a thin section was specifically stained with these mAbs, indicating that these mAbs directed against MFGM recognized membrane proteins and glycoproteins of lactating mammary epithelial cells. Upon heating of the MFGM in phosphate buffer, pH 7.4 at 100 degrees C for 10 min, the antigens still retained most of its reactivity to these mAbs, whereas, proteolytic cleavage by trypsin and chymotrypsin strongly reduced its reactivity to these mAbs by 60% or more except for two mAbs which recognized the 57 and 53 kDa glycoproteins, respectively.

Animals↗
PubMed1994

Cultured rat astrocytes possess Na(+)-Ca2+ exchanger.

Na(+)-Ca2+ exchange activity in its reverse mode was demonstrated in cultured rat astrocytes. Combination of ouabain (1 mM) and monensin (20 microM) caused a marked increase in 45Ca2+ uptake in astrocytes. 45Ca2+ uptake was also stimulated by lowering the external Na+ concentration. Ouabain plus monensin-stimulated 45Ca2+ uptake was blocked by 3,4-dichlorobenzamil (IC50, 16 microM), an inhibitor of Na(+)-Ca2+ exchanger, but not by nifedipine (0.1 microM). The stimulated-45Ca2+ uptake was observed even in K(+)-free medium, and external K+ at 5-10 mM caused a 2.2-fold increase in the uptake. Microspectrofluorimetry using the Ca(2+)-sensitive dye fura-2 showed that ouabain plus monensin increased intracellular Ca2+ concentration in single astrocytes. The Ca2+ signal was dependent on external Ca2+ (EC50, 1.4 mM), and blocked by 20 microM 3,4-dichlorobenzamil, but not by Ca2+ channel blockers (Cd2+, 20 microM; Ni2+, 100 microM). Antiserum of cardiac Na(+)-Ca2+ exchanger recognized 160 and 120-135 kDa proteins on SDS-polyacrylamide gel electrophoresis of astrocyte homogenate. Northern blot analysis revealed the presence of mRNA for the exchanger protein in astrocytes. These findings indicate that Na(+)-Ca2+ exchanger which is modulated by K+ is present in cultured rat astrocytes.

Amiloride↗
PubMed1994

Endothelial injury during extracorporeal circulation: neutrophil-endothelium interaction induced by complement activation.

This study was designed to understand the physiologic intravascular and intradevice events at the cellular level following complement system activation during extracorporeal circulation. The addition of anaphylatoxin C5a or complement-activated serum into neutrophil- or endothelial cell-suspensions resulted in a dose-dependent transmembrane stimulation that was assessed by an intracellular free calcium ion mobilization technique using a calcium-sensitive photoprotein, aequorin. The adhesion and ruffle formation of neutrophils on endothelial cell monolayers were markedly enhanced when both cell types were treated with C5a or activated serum. The significance of complement activation on intravascular events during extracorporeal circulation is emphasized and discussed from the viewpoint of surface-expressed adhesion molecules.

Calcium↗
PubMed1994

Signal transduction through gp130 that is shared among the receptors for the interleukin 6 related cytokine subfamily.

Interleukin 6 (IL-6) and related cytokines, such as leukemia inhibitory factor (LIF), oncostatin M (OSM), ciliary neurotrophic factor (CNTF) and IL-11 exhibit multiple functions and redundancy in biological activities and play important roles in the immune response, hematopoiesis, the nervous system and acute phase reactions. These IL-6 family cytokines exhibit a similar helical structure, and their receptors are structurally similar and constitute a cytokine receptor super family. In addition, a receptor subunit is shared among these IL-6 related cytokine subfamily receptors, contributing to one of the mechanisms of functional redundancy of cytokine activities and suggesting the presence of a common signal transduction pathway among these receptors. In this review, we describe the structure of the receptors for IL-6 and its related cytokine subfamily members. Furthermore, we propose a novel mechanism for the generation of cytokine diversity, i.e. the complex of a cytokine and one of its receptor subunits act as a novel cytokine on the cells that express the other receptor subunit(s) capable of acting as a receptor for the complex. Finally, we describe a Ras-independent novel signal transduction pathway that utilizes Jak tyrosine kinase family, Stat protein family and yet unidentified H-7-sensitive pathway. This signal transduction pathway is commonly generated through the receptors for a wide range of cytokines and growth factors.

Animals↗
PubMed1994

Intra-operative radiation therapy for malignant brain tumors: rationale, method, and treatment results of cerebral glioblastomas.

In radiation therapy for malignant brain tumours, the dose of radiation that can be safely delivered to a tumour is limited by the radiation tolerance of the adjacent normal brain tissue. Among various radiation modalities to produce local tumour eradication without unacceptable complications, we chose a large, single irradiation dose during the operation (intra-operative radiation therapy, IORT). In contrast to X-ray or Cobalt-60 gamma ray irradiation, IORT with a high-energy electron beam delivered by the Shimadzu 20 MeV betatron provides acceptable dose homogeneity with rapid fall-off of the radiation dose beyond the treatment volume. Thus, IORT has the advantage of precise demarcation of the target volume, minimum damage to surrounding normal tissues, and a high absorbed target dose (15-25 Gy in 5-10 min). On the basis of our experience with 170 patients treated by IORT, we established the treatment indications and method in patients with malignant brain tumours. IORT with a dose of 15-25 Gy was delivered to widely resected tumours followed by external radiation therapy. No acute or subacute complications were observed. Treatment results of 30 patients with glioblastoma treated by IORT (mean 18.3 Gy) combined with external radiation therapy (mean 58.5 Gy) resulted in a median survival of 119 weeks and a 2-year survival rate of 61%.

Adolescent↗
PubMed1994

The effect of the neurokinin antagonist FK-224 on the cough response to inhaled capsaicin in a new model of guinea-pig eosinophilic bronchitis induced by intranasal polymyxin B.

Eosinophilic bronchitis without asthma can cause a persistent non-productive cough which is resistant to bronchodilator therapy. To understand the mechanism of the cough in this disorder, an animal model of eosinophilic bronchitis was developed. Guinea-pigs were treated with transnasal administration of polymyxin B or saline twice a week for 3 weeks. The number of eosinophils in bronchoalveolar lavage fluid increased in polymyxin B-treated animals when compared with those treated with saline. In addition, histological examination showed that the number of eosinophils infiltrated into the tracheal epithelium increased; injury to the tracheal epithelium was greater in polymyxin B-treated animals. The numbers of coughs induced by saline and each concentration of capsaicin (10(-18), 10(-16), 10(-14) M) were greater in the polymyxin B-treated animals. FK-224 (a neurokinin receptor antagonist) decreased the heightened cough reflex in this animal model of eosinophilic bronchitis. These findings suggest that neuropeptides, and particularly neurokinins, are involved in the heightened cough receptor sensitivity in eosinophilic bronchitis without asthma. This has implications for better understanding of this disorder and its treatment.

Administration, Inhalation↗
PubMed1994

Distribution of metastatic lymph nodes in colorectal cancer by the modified clearing method.

PURPOSE: The aim of this study was to clarify the distribution of lymph node metastasis in colorectal cancer. We also examined the relationship between the primary tumor (T) and the regional node (N) categories of the TNM (primary tumor, regional nodes, metastasis) classification. METHOD: Lymph nodes of surgical specimens in 311 consecutive patients with colorectal cancer were studied using the modified clearing method. RESULTS: Lymph node metastasis was seen in 59.2 percent of the total cases. The upward metastasis rate was 30.7 percent. In the longitudinal spread, most of the lymph node metastasis was seen within 10 cm. On the oral side in rectal cancer, there was no metastasis beyond 4 cm. The lateral metastasis rate in rectal cancer was 8.8 percent and in the lower rectum, the rate of cancer within 6 cm from the anal verge or beyond pT3 was much higher. CONCLUSION: In the TNM classification, there was no significant difference between colon and rectal cancer except pT1 with rectal cancer. In the lower rectal cancer within 6 cm from the anal verge or beyond pT3, there is a high risk of lateral metastasis, and lateral lymph node dissection or radiation therapy should be performed.

Anus Neoplasms↗
PubMed1994

Surface coating of hydrophilic-hydrophobic block co-polymers on a poly(acrylonitrile) haemodialyser reduces platelet adhesion and its transmembrane stimulation.

Surface design aimed at reduced adhesion and preserved functions of platelets is of great importance for extracorporeal devices. In this study, a coating technique using hydrophilic-hydrophobic block co-polymers on a hydrophobic poly(acrylonitrile) (PAN) haemodialyser was explored. The hydrophilic block of co-polymers was composed of either poly(methoxy polyethylene glycol methacrylate) or poly(dimethyl acrylamide), and the hydrophobic block was poly(methyl methacrylate). The co-polymers were coated on the dialyser membrane by means of a solution coating method. Upon coating, the hydrophobic block of the co-polymers was anchored on a PAN membrane and the hydrophilic block oriented towards the blood-material interface. This was deduced from water wettability measurements. Significantly reduced transmembrane stimulation of platelets was observed, which was evaluated by determining the intracellular calcium ion concentration of platelets eluted through treated hollow fibres. This suppression was enhanced as the relative fraction of the hydrophilic block of the co-polymers increased. Furthermore, the number of platelets adhering to the co-polymer-coated PAN membrane was drastically reduced. Thus, coating of the hydrophilic-hydrophobic block co-polymers provided better biocompatibility on a hydrophobic PAN dialyser.

Acrylamides↗
PubMed1994

Functional role of charybdotoxin-sensitive K+ channels in the resting state of dog basilar artery.

To determine the possible role of Ca(2+)-activated K+ (KCa) channels in the regulation of resting tone of cerebral arteries, the effect of agents which interact with these channels on tension and 86Rb efflux was examined in endothelium-denuded strips of dog basilar artery, and data were compared with findings in the mesenteric artery. The basilar artery maintained a myogenic tone; that is, the resting tone decreased when nifedipine was added. The addition of charybdotoxin, a blocker of large conductance KCa channels, caused a concentration-dependent contraction in the basilar artery but not in the mesenteric artery. In strips preloaded with 86Rb, the basal 86Rb efflux rate constant was significantly greater in the basilar artery than in the mesenteric artery. Nifedipine decreased the basal 86Rb efflux rate constant only in the basilar artery. The basal 45Ca influx in the resting state of the basilar artery was significantly increased when compared with the mesenteric artery and this increase in the basilar artery was reduced by nifedipine. The results suggest that the charybdotoxin-sensitive KCa channels regulate the myogenic tone in the resting state of the basilar artery. The activation of KCa channels in the basilar artery appears to be secondary to the increased transmembrane Ca2+ influx probably via the activation of L-type voltage-dependent Ca2+ channels in the resting state of this artery.

Animals↗
PubMed1994

Post-natal decrease in chronotropic sensitivity to acetylcholine in rat heart.

1. The negative chronotropic effects of acetylcholine and carbachol on isolated rat right atria were examined at 0, 4, 8, and 16 weeks after birth. 2. Acetylcholine produced negative chronotropic responses at all ages and completely abolished spontaneous beating at its maximum effective concentration. 3. The sensitivity to acetylcholine, expressed in terms of ED50 values, was higher at 0 and 4 weeks than at 8 and 16 weeks, ED50 values (microM) at 0, 4, 8 and 16 weeks being 9.5 +/- 1.8 (n = 12), 13.2 +/- 3.4 (n = 11), 59.3 +/- 10.9 (n = 14) and 51.5 +/- 17.5 (n = 5), respectively. 4. Neostigmine produced a leftward shift of the concentration-response curve for acetylcholine both at 4 and 8 weeks after birth. The shift was larger at 8 weeks and no difference in sensitivity to acetylcholine was observed between the two ages in the presence of neostigmine. 5. Further, no developmental changes were observed in the sensitivity to carbachol, which is not hydrolyzed by cholinesterase. 6. We concluded that the chronotropic sensitivity to acetylcholine of rat atria decreases post-natally during the period between 4 and 8 weeks after birth due to increase in cholinesterase activity.

Acetylcholine↗
PubMed1994

Effects of shock waves on the mouse fetus.

Extracorporeal shock wave lithotripsy is contraindicated during pregnancy because its effects on the fetus remain to be ascertained. The purpose of this study was to elucidate the effects of shock waves on fetuses at various stages of pregnancy. Pregnant mice received 100, 250, or 500 shock waves on 8, 10, 12, 14, and 16 days postcoitum. The effect on fetal survival rate and weight was minimal in the early stages of pregnancy. In the later stages of pregnancy, however, the number of viable fetuses decreased in proportion to an increasing number of shock waves, and almost no viable fetuses were found in the group treated with 500 shock waves. Fusion and necrosis were found in many dead fetuses. Histological examination of the fetuses, which was obtained immediately after the shock wave treatment, revealed hemorrhages in the brain, lungs and subcutaneous tissue. This study indicated that shock waves lead to fetal damage and death in the late stage of pregnancy in mice.

Animals↗
PubMed1994

Obstructive azoospermia of unknown origin: sites of obstruction and surgical outcomes.

Although the majority of patients with obstructive azoospermia have medical histories or signs related to seminal tract obstruction, the pathogenesis of the obstruction is unknown in some patients. Of 38 patients with obstructive azoospermia treated at our hospital preoperative data did not indicate causes or sites of obstruction in 6. Operative and pathological findings showed obstruction at the proximal convoluted vas deferens or between the most distal portion of the cauda epididymis and the vas deferens in 8 of 11 blocked seminal tracts. Microsurgical epididymovasostomy resulted in a patent anastomosis in all 6 patients and pregnancy in 2. In patients with obstructive azoospermia of obscure preoperative causes, it is highly probable that the obstruction sites are in the convoluted vas deferens or the transitional region between the cauda epididymis and vas deferens, and that fertility may be restored by microsurgical epididymovasostomy.

Adult↗