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Biomedical subjects

M Iwata

Publications and source records attributed to M Iwata.

At least 505 records · Page 28Linked to original sources
PubMed1987

Characterization of histamine receptors in isolated rabbit veins.

Veins were isolated from 16 sites of the rabbit venous tree and responses to histamine and histamine receptor agonists were studied to characterize the histamine receptors. Isometric contraction and relaxation of ring segment preparations were recorded. Histamine produced concentration-dependent contractions in all veins in the resting state. Both the maximum response and pD2 value varied remarkably from vein to vein and regional differences in sensitivities to histamine varied considerably from previous findings in dog veins. Also in the precontracted state with a vasoconstricting agent, histamine predominantly contracted the veins. The contractile responses to histamine, in both resting and precontracted states, were antagonized competitively by the histamine H1-receptor antagonist, mepyramine. On the other hand, histamine relaxed the precontracted veins, in the presence of mepyramine. Selective H2-receptor agonists, dimaprit and impromidine, relaxed the precontracted veins even in the absence of mepyramine. These responses to histamine were antagonized competitively by the H2-receptor antagonist, cimetidine or ranitidine. The present study provides quantitative and systematic data regarding histamine receptors in rabbit veins. We propose that: 1) there are both vasoconstrictor H1-receptors and vasodilator H2-receptors, 2) histamine generally contracts rabbit veins through predominant H1-receptors and that 3) the H2-receptor-mediated relaxation does not depend on the presence of the endothelium.

Animals↗
PubMed1986

Neutrophils biosynthesize leukotoxin, 9, 10-epoxy-12-octadecenoate.

An epoxy derivative of linoleate, 9,10-epoxy-12-octadecenoate, was demonstrated to be biosynthesized by neutrophils from various sources such as canine and human blood, and guinea-pig peritonea. It was nominated as leukotoxin from its 'toxic' activity onto mitochondrial respiration. From the reaction mixture of leukocytes with linoleate, an isomer of leukotoxin, 12,13-epoxy-9-octadecenoate, and a 'non-toxic' hydroxy derivative of linoleate, 9-hydroxy-12-octadecenoate, were detected. Such a cascade reaction of linoleate by leukocytes was discussed. Biosynthesis of leukotoxin by neutrophils was substantially enhanced by the presence of calcium ion and calcium-ionophore, A23187. Neutrophils contained leukotoxin, ca. 7 f moles/cell, which was extractable by 60% ethanol, but little of the isomer.

Animals↗
PubMed1986

Biosynthesis of leukotoxin, 9,10-epoxy-12 octadecenoate, by leukocytes in lung lavages of rat after exposure to hyperoxia.

In lung lavages of rat after pure oxygen breathing, a toxic linoleate peroxide, 9,10-epoxy-12-octadecenoate, and its isomer, 12,13-epoxy-9-octadecenoate were detected by HPLC analyses. The epoxide(s) was demonstrated to be biosynthesized by incubating linoleate with leukocytes collected from lung lavages, thus nominated to be leukotoxin. The chemical structures of leukotoxin and its isomer were determined by gas-chromatography/mass spectrometry and nuclear magnetic resonance measurements. Leukotoxin showed a potent uncoupling activity to rat liver mitochondrial respiration and a dose-dependent relaxation of rat stomach smooth muscle. These findings were discussed with 'oxygen toxicity' on the lung.

Animals↗
PubMed1986

Relationship between chlordane and its metabolites in blood of pest control operators and spraying conditions.

Chlordane has been widely used to protect soil and house foundations against termite infestation. Pest control operators (PCOs) are occupationally exposed to chlordane. The relationship between chlordane and its metabolites in blood of PCOs and spraying conditions were investigated. Chlordane and its metabolites were detected in the blood of some chlordane-exposed PCOs, but not in that of the controls. Trans-nonachlor and the metabolites oxychlordane and heptachlor epoxide were detected in the blood of PCOs. Total concentration of chlordane and its metabolites in blood (trans-nonachlor + oxychlordane + heptachlor epoxide) was less than 5.6 ppb (mean: 0.89 ppb). The concentration of chlordane and its metabolites in blood of chlordane-exposed PCOs was significantly correlated with the number of spraying days and the amount of chlordane sprayed, particularly with a large correlation coefficient (r = 0.81, P less than 0.001) with the spraying days in the three months prior to the medical examination. The concentration of chlordane and its metabolites in blood is considered to be a useful indicator of biological monitoring for chlordane exposed workers (PCOs).

Adult↗
PubMed1986

Spinocerebellar degeneration with prominent involvement of the motor neuron system: autopsy report of a sporadic case.

A sporadic case of spinocerebellar degeneration with prominent involvement of the motor neuron system is reported. A Japanese male without contributing family history, developed cerebellar ataxia at the age of 52, followed by generalized amyotrophy and ophthalmoplegia, and died aged 58. The clinical findings were pathologically verified as degeneration of the spino-ponto-cerebellar system and the motor neuron system, the latter almost identical to those of amyotrophic lateral sclerosis. Additional subclinical changes were found in the dentate nucleus and substantia nigra. Brain-stem nuclei subserving eye movements were well preserved, suggesting a supranuclear basis for the ophthalmoplegia. This unusual combination of system degenerations has on rare occasions been reported in the heredofamilial cerebellar disorders. As a sporadic case, however, this may be the first autopsy case of spinocerebellar degeneration with severe concurrent involvement of the motor neuron system.

Autolysis↗
PubMed1986

A large calcium-binding protein associated with the larval spicules of the sea urchin embryo.

A tissue-specific, high molecular weight, calcium-binding protein from the sea urchin embryo is described. This protein, designated as CBP 180, has a molecular weight of 180,000 under reducing conditions, and is extractable with 1% Triton X-100. It accumulates rapidly during development, starting roughly at the onset of spiculogenesis. When embryos are cultured in the presence of inhibitors of spicule formation, such as tunicamycin and zinc ions, accumulation of CBP180 is depressed or stopped. By immunofluorescence technique and by using an antibody specifically generated against this protein, CBP180 is mainly localized in primary mesenchyme cells and spicular syncytium of the pluteus larva. Little or none is detectable in ectoderm, endoderm or blastocoelar extracellular matrix. These results suggest that the protein is involved in calcium sequestration in the differentiation of larval spicules.

Animals↗
PubMed1986

Epidermolysis bullosa acquisita: clinical response to plasma exchange therapy and circulating anti-basement membrane zone antibody titer.

Epidermolysis bullosa acquisita has been recognized as a rare autoimmune mechanobullous disorder since the detection of immunoglobulin and complement deposits along the basement membrane zone. A circulating anti-basement membrane zone antibody has also been detected in some cases. We are reporting a case of epidermolysis bullosa acquisita in which clinical symptoms were well correlated with the circulating anti-basement membrane zone antibody titers. Although the patient initially responded very well to corticosteroid therapy, remission could not be maintained without increasing the dosage. Other therapies, including azathioprine, dapsone, vitamin E, and gold sodium thiomalate, produced no beneficial effects. Although a high dose of oral corticosteroid and cyclophosphamide decreased the antibody titer and blister formation, this therapy had to be terminated because of side effects. Plasma exchange therapy in combination with corticosteroid and low-dose cyclophosphamide resulted in a marked decrease of the anti-basement membrane zone antibody titer and clinical improvement. Thus plasma exchange therapy may be a useful adjunct to conventional treatments for patients with epidermolysis bullosa acquisita.

Autoantibodies↗
PubMed1986

Anatomical distribution and immunological characteristics of epidermolysis bullosa acquisita antigen and bullous pemphigoid antigen.

A Japanese patient with epidermolysis bullosa acquisita (EBA) was autopsied, and direct immunofluorescence (DIF) testing was performed. Using this patient's serum (EBA serum) and three bullous pemphigoid (BP) sera, the anatomical distribution and immunological characteristics of EBA antigen and BP antigen were investigated by indirect immunofluorescence (IIF). EBA antigen showed the same anatomical distribution as BP antigen in DIF and IIF studies; both antigens were limited to the skin, tongue, oesophagus, trachea, cornea and bladder. EBA antigen was located on the dermal side of both NaCl and PBS-separated skin, whereas BP antigen was limited to the epidermal side. Ethanol fixation abrogated the antigenic stability of BP antigen, but not that of EBA antigen. No difference was found when acetone or formalin fixation was used. The separation methods and prefixation in ethanol could be useful techniques applicable to the classification of the bullous disorders which manifest circulating anti-BMZ antibodies.

Animals↗
PubMed1986

Effect of human immunoglobulin preparations on experimental Bordetella pertussis infection in mice.

The effects of four kinds of human immunoglobulin preparations for intravenous use [pH-4-treated (IG-100), polyethyleneglycol-treated (PEG-G), sulfonated (S-G) and pepsin-treated (Pep-G)] on intracerebral (i.c.) Bordetella pertussis infection in mice, and on B. pertussis vaccine-induced leukocytosis-promoting factor (LPF) and histamine-sensitizing factor (HSF) were compared with those of human immunoglobulin preparation for intramuscular use (GGN). A prophylactic potential against i.c. B. pertussis challenge was demonstrated in IG-100, PEG-G and GGN. A prophylactic potential was also demonstrated in S-G and Pep-G, although to a lesser extent. Neutralizing activity for LPF was in the following order: GGN = IG-100 = PEG-G greater than S-G = Pep-G; for HSF it was as follows: IG-100 greater than PEG-G greater than GGN = S-G greater than Pep-G. There were no significant differences in antibody titers of the various preparations against B. pertussis antigens. These results suggest that the Fc part of the immunoglobulin molecule is important for protecting against i.c. B. pertussis infection and for neutralizing B. pertussis toxins.

Animals↗
PubMed1986

Opsonic and complement-dependent bactericidal activities of various immunoglobulin preparations for intravenous use.

Some effector functions of various immunoglobulin (IgG) preparations have been compared. Tests for opsonic activity were performed in vitro with human peripheral blood leukocytes and in vivo with mice. The augmentation effects on luminol-dependent chemiluminescence were investigated with human leukocytes. The complement-dependent bactericidal activities were tested with Escherichia coli. Five IgG preparations: pH 4-treated preparation (IG-100), polyethyleneglycol-treated preparation (PEG-G), sulfonated preparation (S-G), pepsin-treated preparation (Pep-G) and a preparation for intramuscular use (GGN) were studied. The results were as follows: (1) IG-100 and PEG-G exhibited strong activities in all test systems; (2) GGN showed a strong opsonic activity; (3) S-G showed relatively weak activities in all test systems, but the revertant S-G preparation exhibited somewhat stronger activities in all systems, and (4) Pep-G showed weak or no activity in all systems. These results suggest that the IgG molecules in IG-100 and PEG-G preparations have satisfactory effector functions. On the other hand, IgG molecules in S-G and Pep-G preparation may have significant deficiencies in their biological functions.

Animals↗
PubMed1986

Protoplast fusion of Lactobacillus fermentum.

Tetracycline-resistant (Tetr) erythromycin-resistant (Eryr) fusants of Lactobacillus fermentum 604 carrying a 10-megadalton Tetr plasmid and L. fermentum 605 carrying a 38-megadalton Eryr plasmid were obtained by means of polyethylene glycol-induced protoplast fusion.

Drug Resistance, Microbial↗
PubMed1986

Partial disconnection syndrome following penetrating stab wound of the brain.

A case of callosal disconnection syndrome caused by a penetrating stab wound of the brain is reported. A portion of the genu and the inferior splenium of the corpus callosum were sectioned by an ice pick without any other significant cerebral damage. We could detect incomplete disconnection left visual alexia by tachistoscopy. It would now appear that the inferior part of the splenium has a significant functional role in transmitting visual verbal codes from the right to the left cerebral hemisphere, but the remaining superior fibers of the splenium may carry some information, albeit less efficiently than the intact structure.

Adult↗
PubMed1986

Distribution of fibronectin, microtubules and microfilaments in the melanophore of the medaka, Oryzias latipes.

Distributions of fibronectin, microtubules and microfilaments in the melanophore of the medaka, Oryzias latipes, were studied using immunofluorescence. We found fluorescent fibers of fibronectin running from the central region to the periphery of the melanophore, but patterns differed depending on whether melanophores had been treated with methanol. Fibrous structures were present in methanol-treated melanophores, whereas only diffuse fluorescence was seen in untreated ones. These fibrous structures, thought to be microtubules, were arranged radially. Actin fibers also showed a radial arrangement, but were not as well organized. In addition, granules with actin immunofluorescence were present.

Actin Cytoskeleton↗