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Biomedical subjects

S Imamura

Publications and source records attributed to S Imamura.

At least 307 records · Page 17Linked to original sources
PubMed1990

Serotonin metabolism in the arthus reaction.

To better characterize the role of serotonin in the Arthus reaction, we examined the concentration of the amine and the activities of serotonin-metabolizing enzymes, monoamine oxidase (MAO) and serotonin-N-acetyltransferase (NAT), in reaction sites induced in guinea pig skin. The specific activity of total MAO in the intact skin was 108.0 +/- 15.9 pmol/min/mg protein, and consisted of about 92% of type A activity and 8% of type B. The activity of total MAO was about 10 times greater than that of NAT. Total MAO activity increased to 130%-150% of control levels at 2 h after initiation of the reaction and approximated the control level at 3 to 6 h. Subsequently, the activity decreased linearly to 50% at 12 h and to 20% at 24 h. Although the time-dependent changes of MAO type A activity were similar to those of total MAO activity, MAO type B activity increased to 42% at 30 min, remained at 30%-40% until 6 h, and then decreased to 20% at 12 h and to 5% at 24 h. NAT activity in the reaction sites decreased with time to 50% of the control at 30 min and to 35% at 4 h and was stationary until 24 h. The serotonin concentration decreased linearly with time to 16% of the control level at 1 h, increased sharply to 240% at 6 h, and remained at more than 200% until 24 h. This biphasic change in serotonin concentration seems to be related to the dynamic changes in the activities of serotonin-degrading enzymes. In addition, the accumulation of platelets in the reaction sites may increase serotonin concentration and MAO activity subsequent to 1 h after the initiation.

Animals↗
PubMed1990

Distribution of fodrin in the keratinocyte in vivo and in vitro.

Distribution of fodrin in the keratinocyte, both in vivo and in vitro, was examined by immunofluorescence microscopy. In the rat epidermis in vivo, fodrin was localized in the cell periphery of the spinous layer of all the skins studied. In only the basal layer of the thick skin, however, fodrin was seen intensely in the cytoplasm. As in vitro keratinocytes, a mouse cell line (Pam 212) cultured in low (0.06 mM) as well as standard (1.87 mM) Ca2+ was examined. In low Ca2+, fodrin was observed throughout the cytoplasm without marked accumulation irrespective of the cell density. The cytoplasmic labeling in low Ca2+ looked filamentous and became aggregated when cells were treated with cytochalasin B; at least some of the aggregates coexisted with those of F-actin. In contrast, fodrin distribution was not affected with colchicine. On the other hand, in standard Ca2+, the protein became concentrated along the cell periphery and less conspicuous in the cytoplasm as the cells reached confluency. When cells were transferred from low to standard Ca2+, the distribution of fodrin changed accordingly within 180 min. The present results indicate that fodrin in the keratinocyte is likely to be associated with actin filaments and that it takes two different ways of distribution both in vivo and in vitro. The peripheral and the cytoplasmic labeling of in vivo and in vitro cells are likely to correspond. It may be that fodrin changes its localization according to the cell's proliferative activity.

Animals↗
PubMed1990

Sweet's syndrome associated with immunoblastic lymphadenopathy.

Sweet's syndrome arose in a 54-year-old Japanese man who had suffered from general malaise, episodic fever, and lymphadenopathy for ten months. Skin symptoms subsided rapidly, but he died three months later with a postmortem diagnosis of immunoblastic lymphadenopathy.

Humans↗
PubMed1990

Photoprotective effect of topically applied superoxide dismutase on sunburn reaction in comparison with sunscreen.

Photoprotective effect of topically applied superoxide dismutase (SOD) to guinea pig skin was compared with a commercially available sunscreen agent after a single exposure to UVB. While cutaneous SOD activity was remarkably decrease in non-treated control animals, both topical SOD and sunscreen agent significantly reduced the decrease in skin SOD activity after UVB irradiation. However, only the sunscreen agent successfully reduced erythema reaction 24h after irradiation but topical SOD failed. These findings suggest that topical SOD protects skin from photo-oxidative damage without affecting erythema response, and thus, from a practical standpoint, sunscreen agents, when compared with topical antioxidants, seem better at present for daily photoprotection.

Administration, Topical↗
PubMed1990

Subclinical dilatation of dermal sweat ducts.

1,323 biopsied skin specimens were retrospectively investigated. Dilatation of dermal sweat ducts was observed in 18 specimens (1.36%). They included 7 specimens of malignant and benign neoplasms or nevi, 5 of fibrosis and 6 of various inflammations. The face was the favored site, but it was also seen in other areas. Ten out of 18 specimens were taken in the summer. It was speculated that the massive secretion of sweat and the compression of sweat ducts by several tissue components in the dermis played an important role for the dilatation of the sweat ducts.

Biopsy↗
PubMed1990

Local response to cardiac overload on myosin heavy chain gene expression and isozyme transition.

It is uncertain whether the shift of cardiac myosin heavy chain (MHC) during pressure overload can be induced by some intrinsic factors or by the stress imposed directly on the individual myocytes. To study whether the changes in cardiac MHC gene expression produced by one-sided overload are limited to the involved ventricle or extend to the other ventricle, we examined MHC gene expression and isozyme transition in the left and right ventricles in aortic coarctated and pulmonary artery-banded rats. It has been confirmed that the pressure overload is indeed limited to the loaded ventricle. The results showed that, compared with sham-operated rats, there was no significant induction of the beta-MHC messenger RNA and corresponding protein in the unloaded ventricle, whereas significant induction was observed in the overloaded ventricle. These results demonstrated that the changes in MHC gene expression and isozyme produced by one-sided ventricular overload are limited to the involved ventricle. We conclude that the MHC gene regulation during hemodynamic overload may not be induced by intrinsic factors, such as hormones, catecholamine, or atrial natriuretic peptide, but is induced by direct local response to increased load.

Animals↗
PubMed1990

Distribution of catecholaminergic receptors in the rat's pancreas islet.

The effects of noradrenaline, adrenaline, isoproterenol, dopamine, apomorphine and their blockers on biphasic insulin secretion induced by 0.3% glucose were observed by means of a modified Lacy's perifusion method. Noradrenaline and adrenaline completely inhibit biphasic insulin secretion, and their effects disappeared completely after pretreatment with phentolamine. Dopamine inhibited the first phase completely and inhibited the second phase partially, and the inhibitory action of the dopamine disappeared after the pretreatment with phentolamine or propranolol. Isoproterenol had no effect on glucose-induced insulin secretion, whereas after treatment with phentolamine, isoproterenol produced a first-phase type of response. Domperidone blocked the effect of dopamine on the suppression of the first phase response. Apomorphine produced the second phase suppression slightly. It was concluded that the sympathetic alpha receptor and DA1 was distributed on the B-cells, the sympathetic beta 2 receptors on the D-cell and the DA2 on the varicosity of the sympathetic beta 2 neuron.

Animals↗
PubMed1990

Chromosomal translocation t(1;22) and sis oncogene variant with gene amplification in a case of atypical malignant lymphoma.

sis Oncogene amplification and PstI restriction enzyme variant were found in a patient of atypical malignant lymphoma with chromosomal translocation t(1;22). A diagnosis of atypical malignant lymphoma was made because dual rearrangements of both beta chain of T-cell receptor gene and heavy and kappa chains of immunoglobulin genes were observed by DNA analysis extracted from the lymph node. Amplification of sis was estimated to be about fivefold by dot blot. BamHI and EcoRI digested DNA hybridized with sis probe from blood and lymph nodes revealed identical bands. Lymph node DNA digested with PstI showed an extra band when compared with DNA samples extracted from peripheral blood. Other oncogenes, such as myb, abl, and myc showed no variant or amplification. These findings suggest that sis is abnormally rearranged in this lymphoma. One possible role of genes on chromosome 22, including sis oncogene, in the pathogenesis of this atypical malignant lymphoma is discussed.

Blotting, Southern↗
PubMed1990

[Basic investigation using K6 diagnostic system. 3. Fabrication of the apparatus wearing a Sensor Alley and the evaluation of its accuracy].

UNLABELLED: An investigation was undertaken to evaluated the accuracy of Sensor Alley, a mandibular movement analyser: K6 Diagnostic System EX with a newly designed auxiliary apparatus. RESULTS: 1) The errors in the values of the standard Sensor Alley were 4.8 mm for the VER-coordinate, 5.0 mm for the AP-coordinate and 3.0 mm for LA-coordinate. 2) The errors of the AP-coordinate were bigger than those of the VER and LA-coordinates. 3) The errors in the values of the standard Sensor Alley fitted with a newly designed auxiliary apparatus were 0.9 mm for the VER-coordinate, 2.0 mm for the AP-coordinate and 1.1 mm for the LA-coordinate. 4) The results led to the conclusion that this newly designed auxiliary apparatus was useful for various studies on mandibular movement used with the K6 Diagnostic System EX.

Diagnosis, Computer-Assisted↗
PubMed1990

Another mechanism for the defect in type III collagen accumulation in Ehlers-Danlos syndrome type IV: increased intracellular degradation of the procollagen.

The nature of type III collagen was examined in the skin and cultured skin fibroblasts from a patient with Ehlers-Danlos syndrome type IV. Although the culture medium contained a much lower amount of Type III collagen than the controls, the cells contained an apparently normal amount of Type III collagen. The patient's Type III procollagen showed no abnormalities in apparent molecular weight, the peptide length as examined by cyanogen bromide cleavage, the genomic DNA size including its C- and N-propeptide portion, mRNA size, or thermal stability; but a pulse-chase study revealed prolonged retention of the type III collagen in the cells. Degradation of Type III procollagen was induced by cell extracts but did not occur in the extracellular space and was inhibited in intact cells by the addition of ammonium chloride or leupeptin to the culture medium. Fluorescent staining showed a characteristic granular deposition of Type III procollagen in the peripheral region of the cytoplasm but no granular deposition of Type I procollagen. These results offer new insight into the mechanism of the decreased amount of Type III collagen in the tissue of patients with Ehlers-Danlos syndrome type IV.

Ammonium Chloride↗
PubMed1990

[Present status of methicillin-resistant Staphylococcus aureus and susceptibility to antimicrobial agents in 6 hospitals in Okinawa].

During the period from November 1987 to March 1988, 301 strains of S. aureus isolated from clinical specimens were collected from 6 hospitals in Okinawa main island. Thirty seven percent of the strains were resistant to methicillin (MRSA, MIC greater than or equal to 12.5 micrograms/ml). There was a difference in an isolation frequency among the hospitals from 13 to 52%. The strains were isolated from pus, sputum and urine with high frequency. As coagulase typing of MRSA, Type II and III strains predominantly isolated with 54% and 40%, respectively. Among the antimicrobial agents tested, about 90-99% MRSA were resistant to beta-lactam antibiotics and aminoglycosides and no resistant strain was observed to MINO. To IPM/CS and OFLX, 84% and 75% of the strains were sensitive, respectively. MRSA is a hospital strain and may be a causative microorganism for a hospital and opportunistic infection.

Aminoglycosides↗
PubMed1990

[Carcinoma complicating ulcerative colitis. Analysis of 8 Japanese cases].

Eight patients with ulcerative colitis complicated by carcinoma were investigated histopathologically on their resected colorectal specimens. Four patients carried multiple tumors, another four patients a solitary tumor. The age at the onset of the colitis in patients with multiple carcinoma was younger in average (27 years old) than that in the patients with a solitary carcinoma (45 years old). Duration of the disease before surgery exceeded 10 years in six of the eight patients. A total of eight tumors of 10 mm or more in dimension were found in four multiple cases, six of them being located in the rectum. These tumors presented peculiar macroscopic features, such as villous, putty-like, nodular, or flat, and were advanced histopathologically, well or moderately differentiated adenocarcinomas in most cases. Six of the eight accompanied areas of epithelial dysplasia adjacent to the carcinoma, the border between carcinoma and dysplasia being vague in three of the six. All multiple cases showed active changes of ulcerative colitis or chronic inflammatory processes such as thickening of the muscularis mucosa, submucosal fibrosis and Paneth cell metaplasia in the crypts. Furthermore, all multiple cases had minute adenocarcinomas, less than 10 mm in diameter, the tumor being restricted to the mucosa or to the mucosa and submucosa. Four of the nine minute carcinomas coexisted with epithelial dysplasia, suggesting that carcinoma developed from dysplasia. On the contrary, the remaining carcinomas carried no dysplasic area with a possibility that carcinoma developed also from nondysplastic atrophic mucosa. Three of the four solitary tumors were conventional adenocarcinomas associated with chronic inflammatory or dysplastic change in the bowel. The specific stainings by lectins and high-iron-diamine (HID) gave no appreciable help in diagnosing the epithelial dysplasia because of unsettled staining results. A large number of argyrophil cells were present in dysplastic epithelia, although the number of such cells was small in carcinomas.

Adenocarcinoma↗
PubMed1990

Elastolytic cutaneous lesions in myeloma-associated amyloidosis.

Elastolytic cutaneous lesions were the initial manifestation of amyloidosis in two patients with multiple myeloma. The skin of the fingertip was noticeably soft, loose, and redundant. The skin of the fingers was depressed with pressure and remained depressed for an abnormally long period of time. Amyloid deposition in the dermis was demonstrated in both cases. In addition, fragmentation and a decrease of elastic fibers in the dermis were observed. Possible explanations for the pathogenesis of such skin lesions were also discussed.

Aged↗
PubMed1989

Cross-linking of lipocortin I and enhancement of its Ca2+ sensitivity by tissue transglutaminase.

The stimulation of human epidermoid carcinoma A431 cells with the calcium ionophore A23187 resulted in the formation of high-molecular-weight lipocortins I, having apparent molecular weights of 75 kDa and 160 kDa as detected with specific anti-lipocortin I antibody. These immunoreactive proteins were identified to be covalently cross-linked multimers of lipocortin I, since essentially the same cross-linked multimers were observed when purified lipocortin I was incubated with tissue transglutaminase (TGase) in vitro. Classical amine substrates for TGase, such as dansylcadaverine and putrescine, were also incorporated stoichiometrically into lipocortin I. Cross-linking or amine incorporation was not observed with lipocortin II. Des 1-26 lipocortin I did not serve as a substrate for TGase, indicating that the N-terminal region of lipocortin I plays an important role in the formation of lipocortin I multimers. The cross-linking of lipocortin I by TGase resulted in a remarkable enhancement of calcium sensitivity for phospholipid binding; i.e., the free calcium concentration required for the cross-linked lipocortin I to attain 50% maximal binding to phosphatidylserine vesicles was as little as 3 microM, while that required for intact monomeric lipocortin I was 20 microM.

Annexins↗
PubMed1989

Enhancement of calcium sensitivity of lipocortin I in phospholipid binding induced by limited proteolysis and phosphorylation at the amino terminus as analyzed by phospholipid affinity column chromatography.

A phospholipid column was prepared by coating siliconized porous glass beads with phospholipids. The analysis of the Ca2+ requirement of lipocortin I and its derivatives in the binding to phospholipids was carried out with this column. The Ca2+ concentration required for 50% binding to the phospholipid column at room temperature was about 30 microM for lipocortin I, while that was reduced to 15 microM when lipocortin I was phosphorylated by the epidermal growth factor receptor/kinase, and a further reduction in the Ca2+ requirement was observed with proteolytic cleavage at the N-terminal region. Cathepsin D and calpain I (low calcium-requiring form of calcium-activated neutral protease) rapidly cleaved human placental lipocortin I at Trp-12 and Lys-26, respectively. These N-terminal-truncated proteins required only 5 microM Ca2+ for 50% binding to the phospholipid column. This enhancement of Ca2+ sensitivity by limited proteolysis was also observed for porcine lung lipocortin I. Essentially the same results were obtained when the Ca2+ sensitivities of the modified lipocortins I were analyzed using dispersed phospholipid vesicles instead of the phospholipid affinity column. Equilibrium dialysis indicated that the release of the N-terminal region markedly increased the affinity of lipocortin I for Ca2+ in the presence of phosphatidylserine, without any appreciable change of the number of Ca2+-binding sites. Limited proteolysis by endogenous proteases such as calpain may be an important regulatory mechanism for the Ca2+ sensitivity of lipocortin I in phospholipid binding.

Amino Acid Sequence↗