Biomedical subjects

T Masuda

Publications and source records attributed to T Masuda.

At least 181 records · Page 10Linked to original sources

PubMed1999

Subarachnoid hemorrhage and myocardial damage clinical and experimental studies.

Subarachnoid hemorrhage (SAH) due to aneurysmal rupture is frequently complicated by cardiopulmonary episodes, including sudden death. We investigated the pathogenesis of cardiopulmonary complications from clinical observation of 715 cases with SAH. There was transient left ventricular asynergy in 9.4% (67/715) of the cases, which consisted of mechanical heart failure and myocardial necrosis. Plasma catecholamine concentration was higher in these patients compared with those without left ventricular asynergy. Transient left ventricular asynergy was considered to result from myocardial derangement: "a panic myocardium," due to a sudden burst of catecholamine. Concerning arrhythmia in SAH, cases with life-threatening arrhythmia, such as ventricular tachycardia or ventricular fibrillation, had higher concentrations not only of plasma catecholamine but also of serum CK-MB, myosin light chain and troponin T, compared with patients who had no ventricular arrhythmia. This implies that life-threatening arrhythmia in SAH would result from myocardial damage due to catecholamine. We devised a novel animal model of SAH in order to clarify the relation between sympathetic nervous activity and myocardial damage immediately after the onset of SAH. The animal experiments showed that sympathetic nervous activity as well as cardiac contractility were transiently elevated, but cardiac function subsequently declined. Serum CK-MB was increased from the onset of SAH and a high value was maintained throughout the entire experimental period. In conclusion, extraordinary transient enhancement of sympathetic nervous activity induces myocardial damage resulting from what is characterized by "a panic myocardium."

Adult↗

PubMed1999

Growing and differentiating characterization of aortic smooth muscle cell line, p53LMAC01 obtained from p53 knock out mice.

Recently we have established an aortic smooth muscle cell line, p53LMAC01 obtained from p53 knockout mice. This cell line showed some differentiated properties which were accelerated by 5-azacytidine treatment [1]. In this study, further characterization of p53LMAC01 cell line was investigated according to cell growth and differentiation, and especially focused into the changes of cell feature, actin filaments' formation, and changes of intracellular calcium concentrations to sympathetic nerve transmitter, norepinephrine. While the cell feature was changed from flattened shape to extended form during 4 days, actin filaments were developing, arranging in parallel to longitudinal direction, and gathering under the surface membrane. In 11 days many cells died and detached from substrate, while actin filaments became poor except for the surface membrane in the remained cells. Appearance of calcium response to noradrenalin needed several days after passage as well as a morphological change of the cells for the extended form and development of actin filaments. The calcium response was maintained on 11 days, which coincided with the result that the cells hold actin filaments under the surface membrane. These results suggest that p53LMAC01 cell line maintains several differentiated characters of adult smooth muscle cell and that their expression needs several days after passage.

Animals↗

PubMed1999

[Changes of arterial blood pressure and heart rate during induction of anesthesia with propofol--efficacy of propofol titration using bispectral index as an indicator].

Bispectral index (BIS) is a processed EEG parameter that measures the hypnotic effects of anesthetic and sedative agents on the brain. We studied whether propofol titration using BIS allows us to prevent hemodynamic changes during induction of anesthesia and endotracheal intubation. Thirty patients without hypertension and obesity were studied. In the titration group (n = 15), BIS was maintained at 40 during induction of anesthesia with propofol. In the bolus group, anesthesia was induced with a bolus infusion of propofol 2 mg.kg-1 (n = 15). Arterial blood pressure and heart rate were recorded before induction of anesthesia, during induction of anesthesia, immediately after, and 1 min, 2 min, and 3 min after intubation. Diastolic blood pressure and heart rate increased significantly after endotracheal intubation in both groups. Systolic blood pressure significantly increased immediately after intubation in the bolus group, but was unchanged in the titration group. These results suggest that BIS is useful to prevent significant increases in systolic blood pressure associated with endotracheal intubation during induction of anesthesia with propofol.

Adolescent↗

PubMed1999

Blood-flow route from the hepatic artery and portal vein to the sinusoid in normal human liver observed by confocal laser scanning microscopy.

OBJECTIVE: To observe the microvasculature in normal human liver. STUDY DESIGN: Four autopsy livers cut into 50-micron-thick sections were observed by confocal laser scanning microscopy. Immunofluorescence was performed using anti-alpha smooth muscle actin (alpha-SMA) antibody. In addition, double immunofluorescence was performed on the other sections using antilysozyme antibody. The routes from the portal vein branches and hepatic artery branches to the sinusoids were defined as follows: portal venule, septal branch, inlet venule, hepatic arteriole and terminal hepatic arteriole. RESULTS: The reactivity of the walls of septal branches and inlet venule was positive for alpha-SMA. Lysozyme-positive cells (Kupffer cells) were dense in the sinusoids but were sparse in the septal branches and absent from the inlet venules. Terminal hepatic arterioles were observed along the septal branch, and the anastomoses between them were observed at the peripheral portion. No routes opening directly from the terminal hepatic arteriole into the sinusoids or arterioportal anastomoses in the portal tract were observed on alpha-SMA-stained sections. CONCLUSION: Regulation of the microcirculation in human liver may be performed by the smooth muscle layer of both peripheral portal and hepatic arterial routes.

Actins↗

PubMed1999

Swelling and flow properties of tubular poly(vinyl alcohol) gels.

Swelling and flow properties of tubular poly(vinyl alcohol) (PVA) hydrogels prepared with the cooling method were investigated using an inflation testing method. When the tubular hydrogel in liquid paraffin was inflated by using liquid paraffin as a pressure transmitting medium, namely in the case that the liquids inside and outside the gel are both liquid paraffin (P/P combination), the gel showed a slight volume change determined by Poisson's ratio of the gel. When the gel in water was inflated by liquid paraffin (P/W combination), the gel swelled to large extent compared with the case of P/P. The hydrogel in W/W combination, namely in the situation that the gel was immersed in water and also inflated by water, showed a very large volume change if the comparison was done at the same pressure. The origin of the volume change in P/P, P/W and W/W combinations is discussed. The volume change in P/P was governed by the Poisson ratio as a material constant (mu 0) of the PVA gels, and the gels swelled by the change in the application of pressure (or deformation) in P/W. The volume change in W/W was closely related to the flow of solvent in the gel.

Gels↗

PubMed1998

Protective actions of 5'-n-alkylated curcumins on living cells suffering from oxidative stress.

To elucidate the roles of 5'-n-alkyl chains of curcumin derivatives in their protective actions on cells against oxidative stress, we compared the efficacy of curcumin and 5'-alkylated curcumins to inhibit the peroxidation of linoleic acid and to protect rat thymocytes suffering from H2O2-induced oxidative stress with their permeation into cells. The inhibitory action of 5'-n-alkylated curcumins on lipid peroxidation increased as the length of hydrocarbon chains of 5'-n-alkylated curcumins was prolonged. This potency order was not confirmed for the protective actions of 5'-n-alkylated curcumins on cells against oxidative stress. Among 5'-alkylated curcumins, the most potent protective action was observed for 5'-n-C3H7-curcumin because it had the greatest permeation into the cells. Further increases in the length of hydrocarbon chains (up to n-C19H39) of 5'-n-alkylated curcumins greatly attenuated their protective actions by reducing their permeation into the cells.

Animals↗

PubMed1998

Changes in lymph vessels and portal veins in the portal tract of patients with idiopathic portal hypertension: a morphometric study.

Little is known about the effects of the pathological process associated with idiopathic portal hypertension (IPH) on hepatic lymph vessels or lymph flow. We used morphometric analysis to examine IPH-associated changes in lymph vessels and branches of the portal vein, with use of immunohistochemical staining for alpha smooth muscle actin. We also quantitated these changes using an image analysis system. The study was conducted with use of liver wedge biopsy material from 10 patients with advanced IPH and 10 control samples from patients with gastric carcinoma without liver disease. The number of lymph vessels, identified by a lack of smooth muscle layer in the wall, and the ratio of the total area of these vessels to that of the portal tract were higher in IPH samples than in the control samples, but the ratio of the area of a single lymph vessel to that of the portal tract in IPH samples was not different from control samples. The number of portal vein branches, characterized by hypertrophy of the smooth muscle layer in IPH samples was not different from control samples. The ratio of the total area of these branches to that of the portal tract, and the ratio of a single portal vein branch to that of the portal tract, were lower in IPH samples than in the control samples. Our results suggest that these morphometric changes in IPH may be associated with a reduction in portal blood flow and increased lymph flow, and that the latter may in turn reduce the high portal vein pressure in idiopathic portal hypertension.

Adult↗

PubMed1998

Inhibitory effect of troglitazone on diabetic neuropathy in streptozotocin-induced diabetic rats.

Free-radical scavengers and inhibitors of tumour necrosis factor-alpha (TNF-alpha) such as N-acetylcysteine and pentoxifylline have been shown to inhibit the development of peripheral neuropathy in streptozotocin(STZ)-induced diabetic rats. In this study we examined the effect of troglitazone, an anti-diabetic thiazolidinedione, on diabetic neuropathy, since it also is a free-radical scavenger and a TNF-alpha inhibitor. Rats were fed powder chow mixed with troglitazone at 0.5% and 0.125% ad libitum. Although blood glucose concentrations were remarkably higher and body weight lower in diabetic than in nondiabetic rats, troglitazone had no effect on these throughout the 24-week experiment. Serum lipoperoxide concentrations, tibial nerve lipoperoxide content and serum TNF-alpha activity induced by lipopolysaccharide was increased in diabetic rats, but inhibited in troglitazone-treated rats. Motor nerve conduction velocity (MNCV) of the tibial nerve slowed in diabetic rats, compared with that in nondiabetic rats. On the other hand, the slowed MNCV was (p < 0.05-0.01) inhibited after weeks 12 and 16 of the experiment in diabetic rats treated with high and low doses of troglitazone, respectively. Morphometric analysis showed that troglitazone suppressed the decrease of the myelinated fibre area (p < 0.05), axon/myelin ratio (p < 0.01) and fascicular area (p < 0.05) and suppressed the increase of myelinated fibre density (p < 0.001) in diabetic rats. These results indicate that troglitazone has a beneficial effect on peripheral neuropathy in STZ-induced diabetic rats irrespective of blood glucose concentrations.

Animals↗

PubMed1998

Electron microscopic examination of oligocilia in naevus of Ota.

The structure of the cilia present in dermal melanocytes of 14 patients with naevus of Ota was examined by electron microscopy. Cilia and basal bodies were found in 10 and 9 lesions, and in 39 and 18 dermal melanocytes, respectively. In each case, 1-12 cells with a single cilium or multiple cilia were observed. In a total of 3 dermal melanocytes from 2 cases, two cilia per cell were observed. The cilia contained 7, 6, 5 and 4 pairs of doublet microtubules in the periphery and no central microtubule. Another pattern with several pairs of doublet microtubules in the periphery and one or two centrally located doublet microtubules were also observed. The latter were not bona fide central microtubules but one and two doublets, which seemed to be displaced to the centre from the periphery of the cilium.

Adolescent↗

PubMed1998

Angiographic follow-up of internal thoracic artery for free bypass grafting.

BACKGROUND: The use of free internal thoracic artery (ITA) grafts in patients with smaller body surface areas has been questioned because of technical difficulties and inadequate graft flow. METHODS: To evaluate postoperative changes in the diameter of free ITA grafts, we performed coronary angiography immediately after coronary artery bypass grafting and then again at a mean of 42 +/- 6 months later. In 20 consecutively treated patients, 21 free ITAs were used as bypass conduits. Two ITA grafts that were patent at the time of the first angiography had closed at the second angiography. Postoperative changes in ITA graft diameter were measured in the 19 patent ITA grafts. RESULTS: At the first angiography, the mean diameters of the proximal, middle, and distal ITA grafts were 2.28 +/- 0.45 mm, 2.34 +/- 0.39 mm, and 2.12 +/- 0.38 mm, respectively. At the second angiography, the mean diameters of the proximal, middle, and distal ITA grafts were 2.85 +/- 0.50 mm, 2.89 +/- 0.53 mm, and 2.72 +/- 0.53 mm, respectively. All segments of the ITA grafts had dilated significantly between the first and second angiographic evaluations (p < 0.01). The percentage change in graft diameter was greater when the initial ITA diameter was less than 2.3 mm (32.0% +/- 28.0%) than when it was 2.3 mm or more (18.8% +/- 11.3%) (p < 0.05). CONCLUSIONS: The postoperative increase in free ITA graft diameter depends on coronary blood flow requirements.

Adult↗

PubMed1998

Gliclazide inhibits diabetic neuropathy irrespective of blood glucose levels in streptozotocin-induced diabetic rats.

N-acetylcysteine and pentoxifylline, free radical scavengers and inhibitors of tumor necrosis factor-alpha (TNF-alpha) production, inhibit the development of peripheral neuropathy in streptozotocin (STZ)-induced diabetic rats. This study was designed to elucidate the effect of gliclazide, an oral hypoglycemic sulfonylurea, on diabetic neuropathy, because it has been indicated to be a free radical scavenger and TNF-alpha inhibitor. Rats were fed with powder chow mixed with gliclazide or glibenclamide as a control ad libitum. Blood glucose levels and body weight were remarkably higher and lower in diabetic than in nondiabetic rats, respectively, while gliclazide and glibenclamide had no effect on these in both diabetic and nondiabetic rats throughout a 24-week experiment. Serum lipoperoxide levels and lipopolysaccharide (LPS)-induced serum TNF-alpha activities were significantly increased in diabetic rats, whereas these were significantly inhibited in gliclazide-treated rats. Motor nerve conduction velocity (MNCV) of the tibial nerve significantly slowed in diabetic rats compared with nondiabetic rats. On the other hand, the slowed MNCV was significantly inhibited in gliclazide-treated diabetic rats after 16 experimental weeks. Morphometric analysis showed that gliclazide prevented decreased myelinated fiber area (P < .05), increased fiber density (P < .001), and decreased axon/myelin ratio (P < .05) in diabetic rats. Glibenclamide treatment did not affect serum lipoperoxide, TNF-alpha, MNCV, or nerve morphology in this experiment. These results indicate that gliclazide has a beneficial effect on peripheral neuropathy in STZ-induced diabetic rats, irrespective of blood glucose levels.

Animals↗

PubMed1998

Association of the missense Glu298Asp variant of the endothelial nitric oxide synthase gene with myocardial infarction.

OBJECTIVES: We examined the possible association between the missense Glu298Asp variant of the endothelial nitric oxide synthase (eNOS) gene and myocardial infarction (MI). BACKGROUND: Endothelium-derived nitric oxide (NO) plays a key role in the regulation of vascular tone. Recently, we reported that a missense Glu298Asp variant in exon 7 of the eNOS gene is a possible genetic factor involved in the pathogenesis of coronary spasm. Endothelium-derived NO also has vasoprotective effects by suppressing platelet aggregation, leukocyte adhesion and smooth muscle cell proliferation. METHODS: We screened 285 patients with an MI and 607 control subjects in Kumamoto Prefecture, Japan. Genotypes were determined by polymerase chain reaction-restriction fragment-length polymorphism analysis. RESULTS: The frequency of the missense Glu298Asp variant was significantly higher in the MI group than in the control group (21.1% vs. 13.3%, p = 0.003, odds ratio 1.73 for the dominant effect of the eNOS T allele). Multiple logistic regression analysis showed that the missense Glu298Asp variant was an independent risk factor for MI, as was diabetes mellitus, hypertension, cigarette smoking, hypercholesterolemia and body mass index. CONCLUSIONS: There was a significant association of the missense Glu298Asp variant of the eNOS gene with MI. This marker-disease association may be due to the impaired effects of NO on the cardiovascular system: dysregulation of vascular tone, platelet aggregation and leukocyte adhesion and smooth muscle cell proliferation, all of which promote coronary atherosclerosis and thrombosis.

Adolescent↗

PubMed1998

Synthesis of (+/-)-cassumunins A and B, new curcuminoid antioxidants having protective activity of the living cell against oxidative damage.

A chemical synthesis of cassumunins A (1) and B (2), natural curcuminoid antioxidants, was developed. The synthesis was started from o-vanillin and after nine reaction steps resulted in 20% and 26% overall yields of 1 and 2, respectively. The synthetic cassumunins showed stronger protective activity than curcumin against oxidative cell death induced by hydrogen peroxide in a rat thymocyte system.

Animals↗

PubMed1998

Nuclear magnetic resonance and biosynthetic studies of neoantimycin and structure elucidation of isoneoantimycin, a minor metabolite related to neoantimycin.

In preparation for biosynthetic studies on the 3,4-dihydroxy-2, 6-dimethyl-5-phenylvaleric acid portion of neoantimycin (1), the 1H and 13C NMR signals of 1 were assigned unambiguously by means of 2D correlation spectroscopy and NOE experiments. The previously undetermined absolute stereochemistry at C-15 and C-16 was deduced as (S) and (S). The structure of isoneoantimycin (2) was also elucidated. The methyl groups of methionine and propionate were incorporated stereospecifically into C-13 and C-12 of 1, respectively, and the configuration of the methyl group of methionine is inverted in the process. The results also suggest the intervention of phenylpyruvate as an actual precursor.

Anti-Bacterial Agents↗

PubMed1998

Differential localization of Th1 and Th2 cells in autoimmune gastritis.

The vast majority of CD4+ T cells infiltrating into gastric mucosa (GM) and in the draining (gastric) lymph node (GLN) shows an activated/memory phenotype, CD45RB(low) L-selectin(low) CD44(high), in neonataly thymectomized BALB/c mice bearing autoimmune gastritis (AIG), indicating that these cells are actively involved in this disease. CD4+ T cells sort-purified from GLN expressed mRNAs encoding for both IFN-gamma and IL-4. However, those infiltrating into GM expressed very low levels of IL-4 mRNA, even though they strongly expressed IFN-gamma mRNA. Among CD4+ T cells separated from AIG mice expressing detectable levels of either IFN-gamma or IL-4 by intracellular staining, less than one-seventh expressed IL-4 and thus most of them expressed IFN-gamma in GM, whereas roughly half and one-third expressed IL-4 in GLN and spleen respectively. These findings indicate that the Th1 cells predominantly infiltrate into autoimmune lesions and Th2 cells are mainly resident in the regional LN. We further set up an in vitro model system of transendothelial migration using a murine endothelial cell line, F-2, and found that Th1 cells in CD4+ T cells separated from lymphoid tissues of AIG mice preferentially passed through the monolayer of endothelial cells while only a small portion of Th2 cells did so. This differing ability of transendothelial migration and localization might explain the dominance of Th1 cells destroying the tissue in focal lesions without inhibition by the Th2 cells, in spite of both subsets being simultaneously activated in AIG mice, and the functions of each T cell subset seems to be mutually exclusive.

Animals↗

PubMed1998

Purification of a novel type of SDS-dependent protease in maize using a monoclonal antibody.

A protease which was activated by SDS was purified to homogeneity from maize leaves. On the basis of its proteolytic activity towards ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) or a synthesized peptide, the purification was carried out using immunoaffinity chromatography with a monoclonal antibody raised against a partially purified enzyme by native gradient PAGE. The purified protease showed three bands at 40, 15, and 13 kDa on SDS-PAGE, indicating that it was composed of heterogeneous subunits. The protease was specifically activated by SDS (optimum = 0.4% for Rubisco proteolysis), but not by poly-L-lysine, fatty acids, or ATP. The protease had a pH optimum around 4.9. beta-Mercaptoethanol stimulated the activity only in the presence of SDS. The proteolytic activity was sensitive to E-64 and leupeptin but was resistant to EDTA, suggesting that the enzyme was an SH-protease. Thus, this enzyme is a novel type of SDS-dependent protease which differs from proteasome, matrix metalloproteinase, and other proteases reported in many organisms.

Animals↗

PubMed1998

Cloning and expression of the soybean chlH gene encoding a subunit of Mg-chelatase and localization of the Mg2+ concentration-dependent ChlH protein within the chloroplast.

From the soybean cDNA library, we isolated and analyzed the chlH gene encoding a subunit of Mg-chelatase. The subunit was a polypeptide of 1,383 amino acids with a molecular mass of 153,491 Da, which shared 90% identity with the olive gene from Antirrhinum majus. The regulation of the expression of chlH was investigated in photomix-otrophic soybean suspension cells (SB-P). The expression was light-inducible, and the induction was more rapid than those of chlI and cab2. Furthermore, the levels of the transcripts and products of chlH appeared to be regulated by a circadian oscillation. The subchloroplastic localization of ChlH was investigated by immunoblot analyses with antiserum against recombinant ChlH. Depending on the concentration of Mg2+ in the lysis buffer, the localization of ChlH protein migrated between the stroma and the envelope membrane; ChlH was localized on the envelope membrane, a major site of chlorophyll biosynthesis, when the Mg2+ concentration of the lysis buffer was high (above 5 mM). These results indicated that the activity of Mg-chelatase was regulated by modulation of the expression and subchloroplastic localization of ChlH protein.

Amino Acid Sequence↗

PubMed1998

Growth, pigmentation, and expression of the puf and puc operons in a light-responding-repressor (SPB)-disrupted Rhodobacter sphaeroides.

We previously cloned a trans-repressor, SPB, for the puf operon of Rhodobacter sphaeroides (Shimada et al. 1996) and revealed that SPB was a putative genetic counterpart to HvrA in Rhodobacter capsulatus, a trans-activator for the puf and puh operons (Mizoguchi et al. 1997). In this study we constructed a spb-disrupted R. sphaeroides, strain L-7, to elucidate the function of SPB. This disruption of the spb gene increased the photosynthetic growth rate and the cellular levels of photopigments under low-intensity light conditions. The disruption also derepressed the expression of the puf and puc operons under high-intensity light conditions. In strain L-7, however, strong illumination still reduced the cellular levels of photopigments as it did in the wild strain, suggesting that SPB did not directly affect the formation of photopigments. These results support our previous suggestion that SPB functions as a high-light repressor for puf operon in R. sphaeroides in striking contrast to HvrA, which is a low-light activator for puf and puh operons in R. capsulatus, even though SPB and HvrA are highly homologous. Disruption of spb gene had no effect on the oxygen-mediated regulation of the pigmentation or the expression of puf and puc operons.

Bacterial Proteins↗