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Biomedical subjects

A Ito

Publications and source records attributed to A Ito.

At least 397 records · Page 22Linked to original sources
PubMed1996

Disappearance of coronary artery-ventricular fistulas after a radical operation for tetralogy of Fallot.

A 42-year-old Japanese man was diagnosed as tetralogy of Fallot (TOF). Coronary arteriography demonstrated coronary artery-ventricular fistulas (left coronary artery to left ventricle, right coronary artery to right ventricle). A radical operation for TOF was performed, including a patch closure of the ventricular septal defect, right ventricular muscle resection and a patch enlargement of the right ventricular outflow tract. After the operation, coronary arteriography showed a marked decrease in the shunt flow through the coronary artery-ventricular fistulas. Six months later, the patient was diagnosed as postoperative constrictive pericarditis, while the fistulas had almost completely disappeared. After pericardiectomy, when all hemodynamic variables were normal, the fistulas did not reappear. This is the first report of TOF complicated with multiple coronary artery-ventricular fistulas which completely disappeared after a radical operation. It is conceivable that in our case coronary artery-ventricular fistulas partially compensated for reduced arterial O2 saturation and disappeared after surgical correction with an improvement in hemodynamic variables.

Adult↗
PubMed1996

[Effects of long-term physical training on body composition, cardiovascular function, and serum lipids in mildly obese middle-aged subjects].

To investigate the effects of long-term physical exercise on humans, body composition, cardiovascular function and serum lipids were measured for a training period of 20 months in 8 men and 8 women, aged 36-67 years who were mildly obese. The subjects participated in physical training for 90 minutes about twice a week for 20 months. The intensity of training was at most 60% VO2max for each subject as calculated by karvonen's formula. The results are summarized as follows: (1) Body weight and estimated body fat weight decreased from baseline after the training in both sexes. The percentage decreases in body weight and estimated body fat weight in men were about threefold those in women. (2) Following the training, heart rate, blood pressure and rate pressure product (RPP) at rest had significantly decreased from initial levels in both sexes. (3) Following the training, the physical work capacity at a heart rate of 150bpm significantly increased, and systolic blood pressure at the heart rate of 150bpm significantly decreased from baseline levels in both sexes. (4) Following the training, the serum HDL-cholesterol and HDL-/total-cholesterol ratio significantly increased from baseline, and serum triglycerides and total cholesterol also significantly decreased from baseline levels in both sexes. These results suggest that long-term physical training with moderate intensity improves body composition, cardiovascular function and serum lipids in mildly obese middle-aged men and women, and reduces the risks for coronary heart disease.

Adult↗
PubMed1996

Intestinal ciliates found in the feces of Japanese native Tokara pony, with the description of a new genus and a new species.

The composition of intestinal ciliates excreted in the feces of 20 Tokara native ponies kept in Iriki farm of Kagoshima University was surveyed. Eleven genera consisting of 18 species were identified based on the description of Strelkow. One new genus including a new species, Wolskana tokarensis n. gen., n. sp., of the family Buetschliidae was recognized and described. The average ciliate density of all horses was 13.8 x 10(3)/ml. Those of stallions (n = 5), mares (n = 11) and foals (n = 4) were 3.9, 16.1 and 43.3 x 10(3)/ml respectively. The value of stallions was significantly lower and that of foals higher than that of mares. Brillouin's diversity index of all horses was 1.554 on average. The index of stallions, 1.470, was significantly lower than those of mares, 1.539, and foals, 1.698. The average number of species per host was 11.7.

Aging↗
PubMed1996

Blockade of the estrogen induced increase in progesterone receptor caused by propylthiouracil, an anti-thyroid drug, in a transplantable pituitary tumor in rats.

It is well known that estrogen (E2) induces progesterone receptor (PR) in the uterus and the mammary gland. In MtT/F84, a pituitary tumor, which was established in our laboratory and has been maintained with in vivo passages, we investigated the PR regulation by E2 in relation to the host's thyroidal status. The PR level in the tumor had increased five fold 48 h after an E2 injection. When the host rats were treated with propylthiouracil (PTU), an anti-thyroid drug, the induction of PR after an E2 injection was completely blocked. This result is consistent with our previous findings indicating that E2 responsiveness in the tumor may be under the control of thyroid hormones. The estrogen receptor (ER) level in the tumor treated with PTU was 15% of the control. This low ER level may account for the blocking of PR induction after an E2 injection. When the host animals were continuously treated with various doses of E2, the PR level in the tumor rose in correlation with the E2 doses. PTU administration, however, did not prevent long term induction of PR by continuous E2 treatment. Our findings suggest that PTU lower the ER level and suppresses the short term estrogenic actions such as PR induction after an E2 injection.

Animals↗
PubMed1996

Sequential changes in the harderian gland of rats exposed to high intensity light.

We examined sequential changes in histology, fluorescent microscopy, and porphyrin content in the Harderian glands of 55 male Wistar rats exposed to fluorescent light of 2,500 or 1,600 lux for 12 h a day up to 8 days and of 10 control rats. After exposure for 1 day there was severe necrosis of the glandular cells, with edema and cellular infiltration of the Harderian gland adjacent to the retina. After exposure for 4 and 8 days these changes regressed and glandular cells regenerated. Red fluorescence in frozen sections of glands from control rats was interpreted to be due to porphyrins. The red fluorescence was faint in glandular acini injured by exposure to light for 4 and 8 days, and porphyrin content of the gland decreased after 4 and 8 days. Homogenates of the Harderian glands from five control rats caused marked hemolysis after exposure to sunlight. Thus exposure to high-intensity light induced necrosis of the glandular cells in the Harderian glands. The injury appeared to be a direct effect of light on the glandular cells, probably as a result of photodynamic action on the porphyrins in the gland.(ABSTRACT TRUNCATED)

Animals↗
PubMed1996

The role of fibroblast growth factor-2 in the vascular effects of interleukin-1 beta in porcine coronary arteries in vivo.

OBJECTIVE: We recently demonstrated that chronic treatment with interleukin-1 beta (IL-1 beta), a major inflammatory cytokine found in atherosclerotic lesions, induces coronary arteriosclerotic changes and vasospastic responses to serotonin and histamine in pigs in vivo and that those responses are partially mediated by platelet-derived growth factor (PDGF). This study was designed to examine, first, whether the effects of IL-1 beta are also partially mediated by fibroblast growth factor-2 (FGF-2), which is another important growth factor in atherosclerotic lesions, and, secondly, whether chronic treatment with FGF-2 per se also induces histological and functional changes in porcine coronary arteries in vivo. METHODS: Porcine coronary arteries were aseptically wrapped with cotton mesh absorbing IL-1 beta with or without neutralizing antibody to FGF-2. In a separate series of experiments porcine coronary arteries were chronically treated with FGF-2 itself in the same manner. Coronary vascular responses in vivo and histological changes were examined 2 weeks after the operation. RESULTS: Coronary vasospastic responses to serotonin and histamine and neointimal formation were induced at the site of the coronary artery where IL-1 beta was chronically and locally applied. These responses were significantly suppressed by co-treatment with a neutralizing antibody to FGF-2 but not by that with non-immune IgG. Immunostaining revealed the presence of FGF-2 in the endothelial cells, the thickened intima and the media at the IL-1 beta-treated site. Furthermore, chronic treatment with FGF-2 also induced coronary vasospastic responses to serotonin and histamine and neointimal formation. CONCLUSIONS: These results suggest that the vascular effects of IL-1 beta may also be mediated by FGF-2 in our swine model and that chronic treatment with FGF-2 also causes coronary arteriosclerotic changes and vasospastic responses in vivo.

Animals↗
PubMed1996

Expression of vacuolating cytotoxin in clinical isolates of Helicobacter pylori.

Our objective was to determine whether the prevalence of vacuolating cytotoxin production differed among Helicobacter pylori isolates obtained from patients with chronic gastritis, gastric ulcer, or duodenal ulcer. We examined the vacuolating cytotoxin production of 114 clinical H. pylori isolates in rabbit gastic epithelial cells (RGECs). We also tested two positive control strains (NCTC 11637 and NCTC 11916). Seventy-four of the 114 H. pylori clinical isolates (64.9%) produced intracellular vacuolation in RGEC cells, but there was no significant difference in the prevalence of intracellular vacuolation among the isolates of patients with chronic gastritis, gastric ulcers, and duodenal ulcers. We found no strong correlation between vacuolating cytotoxin production and peptic ulceration.

Animals↗
PubMed1996

[Detectability of simulated nodules on chest phantom by Fuji computed radiography: comparison of different nodule sizes, configurations and tube voltages].

The detectability of simulated nodules placed on a chest phantom and shown on FCR images has been studied. Different tube voltages (130 kVp, 100 kVp), presence or absence of compensation filter, various sites and different sizes (5 mm/10 mm) and configurations (spherical or broad based) of the nodule were examined. 112 FCR chest phantom images were evaluated by ten radiology specialists utilizing ROC analysis. The detection rate for nodules was influenced in general by the site. The detection rate was as follows in decreasing order: intercostal, overlaid with one rib, two ribs, diaphragm and heart. Detection of nodules of 10 mm in height was mainly influenced by the density of the lung where the nodule was located, whereas that of nodules of 5 mm in height was more dependent on the site of the nodule, probably greatly influenced by the amount of structure mottle. Spherical nodules of 5 mm in height were more frequently recognized than the broad-based ones. High kVp (130 kVp) resulted in a higher detection rate for both sizes of nodules than low kVp (100 kVp). Detection of spherical nodules overlying the heart or diaphragm was improved with the use of a compensation filter.

Humans↗
PubMed1995

Analysis of elements in the substrate required for processing by mitochondrial processing peptidase.

We have recently demonstrated that synthetic peptides modeled on the extension peptide of malate dehydrogenase can be a good substrate of mitochondrial processing peptidase and that arginine residues present at positions -2 or -3 and distant from the cleavage point were important for recognition by the enzyme (Niidome, T., Kitada, S., Shimokata, K., Ogishima, T., and Ito, A. (1994) J. Biol. Chem. 269, 24719-24722). We further investigated the elements required for substrates of the protease. To analyze the reaction by a more rapid yet quantitative method, we have developed intramolecularly quenched fluorescent substrates. Using the fluorogenic substrates we demonstrated that at least one of the proline and glycine between the distal and proximal arginine residues was also important while other connecting sequences were dispensable. In addition, the protease showed considerable preference for aromatic and, to a lesser extent, hydrophobic amino acids in the P1'-position. These results together with the previous data suggest that the proximal and distal arginine residues, proline and/or glycine between them, and P1' amino acid could be critical determinants for the specific cleavage of the substrates by the protease.

Amino Acid Sequence↗
PubMed1995

Purification and characterization of a new serine proteinase from Bacillus subtilis with specificity for amino acids at P1 and P2 positions.

A proteinase was purified 230-fold to apparent homogeneity from culture filtrates of Bacillus subtilis by a series of column chromatographies on DE52, DEAE-Toyopearl, Cellulofine GC200M, and Mono-Q, using Boc-Ala-Ala-Pro-Ser-pNA as a substrate. The molecular weight of the proteinase was estimated to be 42,000 by SDS-PAGE in the presence of 2-mercaptoethanol. Studies on the substrate specificity with peptide p-nitroanilides and natural peptides revealed that this proteinase preferentially hydrolyzed the peptide bond on the carboxyl-terminal side of either serine or alanine residues at the P1 position and hydrophobic bulky amino acids at P2. It was most active at pH 9.5 for the hydrolysis of Boc-Ala-Ala-Pro-Ser-pNA. The enzyme was inactivated by diisopropyl fluorophosphate (DFP), but not by tosyl-L-phenylalanine chloromethylketone (TPCK) or by EDTA. Based on the reactivity toward substrates and inhibitors, this enzyme differs from elastase- or subtilisin-like proteinase, hence it is a new type of proteinase with specificity for amino acids at P1 and P2 positions.

Amino Acid Sequence↗
PubMed1995

Chronic inhibition of endothelium-derived nitric oxide synthesis causes coronary microvascular structural changes and hyperreactivity to serotonin in pigs.

BACKGROUND: Endothelium-derived nitric oxide (NO) is believed to regulate myocardial perfusion and structural changes in the vascular wall. Our objective was to determine whether chronic inhibition of NO synthesis causes structural and functional changes in coronary arteries. METHODS AND RESULTS: Coronary vasomotor response was studied in pigs before and after chronic oral administration of the NO synthesis antagonist N omega-nitro-L-arginine methyl ester (L-NAME) 30 mg.kg-1.d-1 for 2 weeks. Chronic L-NAME treatment increased (P < .01) arterial pressure but did not alter baseline coronary blood flow (CBF), epicardial coronary diameter, or heart rate. Chronic L-NAME treatment augmented (P < .01) the decrease in CBF in response to intracoronary serotonin (30 micrograms/kg) from 5 +/- 14% to 40 +/- 5% but did not alter the CBF response to prostaglandin F2 alpha. The serotonin-induced decrease in CBF after acute L-NAME administration was still less before (1.3 +/- 0.4%) than after chronic L-NAME treatment (51 +/- 6%). Chronic L-NAME treatment attenuated the increase in CBF with bradykinin (100 ng/kg) but did not alter the CBF response to nitroglycerin (10 micrograms/kg). Compared with intact pigs without L-NAME treatment, L-NAME-treated pigs had significant thickening of the media in the microvessels (diameter, < 300 microns) but not in the large epicardial vessels. Chronic intracoronary infusion of L-NAME at 3 mg.kg-1.d-1 for 2 weeks, which did not produce arterial hypertension, caused similar microvascular medial thickening. CONCLUSIONS: These results indicate that chronic administration of L-NAME caused coronary microvascular structural changes and hyperreactivity to serotonin in pigs in vivo, suggesting an important role of defective NO synthesis in coronary microvascular disorders.

Animals↗
PubMed1995

D1 cap region involved in the receptor recognition and neural cell survival activity of human ciliary neurotrophic factor.

Human ciliary neurotrophic factor (hCNTF), which promotes the cell survival and differentiation of motor and other neurons, is a protein belonging structurally to the alpha-helical cytokine family. hCNTF was subjected to three-dimensional structure modeling and site-directed mutagenesis to analyze its structure-function relationship. The replacement of Lys-155 with any other amino acid residue resulted in abolishment of neural cell survival activity, and some of the Glu-153 mutant proteins had 5- to 10-fold higher biological activity. The D1 cap region (around the boundary between the CD loop and helix D) of hCNTF, including both Glu-153 and Lys-155, was shown to play a key role in the biological activity of hCNTF as one of the putative receptor-recognition sites. In this article, the D1 cap region of the 4-helix-bundle proteins is proposed to be important in receptor recognition and biological activity common to alpha-helical cytokine proteins reactive with gp130, a component protein of the receptors.

Amino Acids↗
PubMed1995

G protein beta gamma subunit activates Ras, Raf, and MAP kinase in HEK 293 cells.

Using transient transfection of HEK 293 cells, we have studied the activation of Ras, c-Raf, and MAP kinase by G protein-coupled receptors, activated G protein alpha subunit (G alpha), and beta gamma subunits (G beta gamma). The expression of constitutively activated Gs alpha, Gi alpha, and G11 alpha did not have any effect on MAP kinase phosphorylation. In contrast, overexpression of G beta gamma could stimulate the phosphorylation of MAP kinase and enhance the MEK kinase activity of c-Raf. Coexpression of dominant negative Ras inhibited G beta gamma-induced phosphorylation of MAP kinase. Furthermore, the GTP-bound form of Ras was increased by overexpression of G beta gamma. These results strongly suggest that the G beta gamma may play an important role in signaling from G protein-coupled receptors to the MAP kinase pathway, and the activation of Ras and c-Raf may be involved in this signaling cascade in HEK 293 cells.

Cell Line↗