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Biomedical subjects

N Sugimoto

Publications and source records attributed to N Sugimoto.

At least 199 records · Page 11Linked to original sources
PubMed1989

Effects of substrate structure on the kinetics of circle opening reactions of the self-splicing intervening sequence from Tetrahymena thermophila: evidence for substrate and Mg2+ binding interactions.

The self-splicing intervening sequence from the precursor rRNA of Tetrahymena thermophila cyclizes to form a covalently closed circle. This circle can be reopened by reaction with oligonucleotides or water. The kinetics of circle opening as a function of substrate and Mg2+ concentrations have been measured for dCrU, rCdU, dCdT, and H2O addition. Comparisons with previous results for rCrU suggest: (1) the 2' OH of the 5' sugar of a dinucleoside phosphate is involved in substrate binding, and (2) the 2' OH of the 3' sugar of a dimer substrate is involved in Mg2+ binding. Evidently, the binding site for a required Mg2+ ion is dependent on both the ribozyme and the dimer substrate. The apparent activation energy and entropy for circle opening by hydrolysis are 31 kcal/mol and 50 eu, respectively. The large, positive activation entropy suggests a partial unfolding of the ribozyme is required for reaction.

Animals↗
PubMed1989

Isolation and purification by high performance liquid chromatography of a tetanus toxin fragment (fragment [A-B]) derived from mildly papain-treated toxin.

Fragment [A-B] of tetanus toxin was highly purified by combination of gel permeation chromatography, adsorption chromatography in an HPLC and immunoadsorption chromatography using anti-Fragment [C] as a ligand. The purified Fragment [A-B] (200 micrograms) elicited a peculiar toxicity, 'hypoactivity' or 'weakness', and killed the mice in ca. 73 hr and 88 hr when it was injected i.v. and i.m., respectively. However, contamination by the whole toxin was not detectable, in the purified fragment preparation, when up to 600 micrograms was tested by the mouse toxicity assay.

Animals↗
PubMed1989

Blocking effects of tetanus toxin and its fragment [A-B] on the excitatory and inhibitory synapses of the spinal motoneurone of the cat.

A highly purified fragment [A-B] preparation (5.5 micrograms of protein in 5 or 10 microliters which is far less than the minimal lethal dose), free from contamination with the whole toxin, was injected intraspinally into the neighbouring area of the gastrocnemius motoneurone pool (eight cats). Tetanus toxin (27 micrograms protein, about 100 LD50) in 5 or 10 microliters (four cats) and 10 microliters of Ringer's solution (four cats) were injected in the same way. Fragment [A-B] depressed both the monosynaptic reflex (MSR) of the gastrocnemius motoneurone pool and its inhibition by conditioning stimulus on the antagonistic peroneal nerve almost simultaneously in the individual cats, in contrast to the whole toxin which blocked first the inhibition of the MSR and later the MSR itself. The effects of fragment [A-B] appeared late, at about the time when the whole toxin blocked the MSR. The cats injected with fragment [A-B] did not die by intoxication. Fragment [A-B] at high doses (up to 120 micrograms) injected intramuscularly into the rat had no effect on neuromuscular transmission. The results clearly showed a blocking action of fragment [A-B] on inhibitory and excitatory synapses of the spinal motoneurones.

Animals↗
PubMed1989

Isolation, purification, and characterization of fragment B, the NH2-terminal half of the heavy chain of tetanus toxin.

Fragment B, the N-terminal half of the heavy chain, an important domain of the tetanus neurotoxin molecule, was isolated for the first time. Tetanus toxin (composed of three domains, A, B, and C) was prepared from culture filtrates. Fragment A-B, derived from the toxin treated mildly with papain, was used for the isolation of fragment B. Fragment A-B obtained was dissociated into fragments A and B by reduction with 100 mM dithiothreitol and treatment with 2 M urea. Fragment B was separated from fragment A by ion-exchange column chromatography on a Mono Q column equilibrated with 20 mM Tris hydrochloride buffer (pH 7.6), containing 1 mM dithiothreitol and 2 M urea, in a fast-protein liquid chromatography system by elution with a linear gradient of 0 to 0.5 M NaCl. Fragment B was obtained in two forms having molecular weights of 48,000 +/- 2,000, which were indistinguishable by sodium dodecyl sulfate-gel electrophoresis or antigenic specificity, but distinguishable on polyacrylamide gel electrophoresis without sodium dodecyl sulfate and on isoelectric focusing (pI 6.7 and 7.3). The recovery of fragment B was 50 to 72% of that of fragment A-B on a molar basis. Purified fragment B was not toxic to mice on intravenous or intramuscular injection at doses of up to 100 micrograms, but was found to form channels (ca. 2.3 pS) in a lipid bilayer membrane by a patch clamp technique. The role of domain B of the tetanus toxin molecule in the mechanism of action of the toxin is discussed.

Amino Acid Sequence↗
PubMed1989

[Granuloma formation in mice by liposomes of new glycolipid containing mycolic acids, "trehalose 2,3,6'-trimycolate"].

After intravenous administration of liposomes containing a novel glycolipid, trehalose 2,3,6'-trimycolate, isolated from Rhodococcus aurantiacus, the granuloma formation was observed distinctively in the lungs, spleen and liver of ICR mice. The concentration of the glycolipid in liposomes influenced profoundly on the inducibility for granulomas and the liposomes containing 10 mol% of trehalose 2,3,6'-trimycolate showed the highest activity for the granuloma formation in mice without a significant loss of body weight of mice with a less toxicity. EggPC liposomes are of more highly inducible for the granuloma formation in mice than eggPC:PS (7:3, mol ratio) liposomes or eggPC:Chol (9:1, mol ratio) liposomes, suggesting that cholesterol in liposomes was not necessarily essential for inducing granulomas in mice. Among the various PC liposomes, synthetic dimyristoyl-phosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) liposomes were of highly inducible, although a high responsiveness was also observed with natural lecithines such as egg or soy PC. However, distearoylphosphatidylcholine (DSPC) liposomes did not show any activity for the granuloma formation in any organs of mice. Organ responsiveness differed significantly in the micelle forms injected. Glycolipid entrapped with eggPC-Chol liposomes showed a lower lung index below 1.0, in contrast to w/o/w micelles containing Freunds' incomplete adjuvant, which showed a higher granuloma formation in the lungs. It was also noted that the toxicity of glycolipid containing liposomes was comparatively lower than the toxicity of glycolipid containing w/o/w micelles, indicating that the liposomes appeared to be more suitable for the induction of the immunomodifying activities of mycolic acid-containing glycolipids than w/o/w micelles.

Animals↗
PubMed1989

[An immune adjuvant activity of mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate, derived from Gordona aurantiaca].

A mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate (GaGM), derived from Gordona aurantiaca, an acid-fast bacterium closely related taxonomically to Mycobacterium, was investigated for its immune adjuvant activity on cell-mediated responses in the mouse. I.V. injection of liposomes containing GaGM enhanced the generation of cytotoxic T-lymphocyte (CTL) against syngeneic and allogeneic tumor cells. In addition, the injection of GaGM augmented the natural killer (NK) activity and the antibody-dependent cellular cytotoxicity (ADCC). These results suggest that the injection of GaGM induces the production of interleukin-2 (IL-2), since such effector cells as CTL, NK and K cells have been shown to require IL-2 for their development.

Adjuvants, Immunologic↗
PubMed1989

[In vitro activation of immune cells by a mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate, derived from Gordona aurantiaca].

A mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate (GaGM), derived from Gordona aurantiaca, an acid-fast bacteria closely related taxonomically to Mycobacterium, was investigated for its immune adjuvant activity in vitro. The liposomes containing GaGM showed strong mitogenic effects on murine spleen cells at the doses used (25-100 micrograms/ml), but not on T-cell-depleted spleen cells or macrophage-depleted spleen cells. These results suggest that the mitogenic property of liposomes containing GaGM differs from that of such as lipopolysaccharide, a B-cell mitogen and that its mitogenic effects depend on the presence of macrophages. In addition, liposomes containing GaGM augmented the mixed lymphocyte reaction (MLR) and in vitro induction of cytotoxic T-lymphocytes (CTLs) against allogeneic tumor cells. These results suggest that liposomes containing GaGM have immune adjuvant properties in vitro and the adjuvant activity may be related to such cytokines as interleukin-1 and -2.

Adjuvants, Immunologic↗
PubMed1989

[Clinicopathologic investigation of 63 cases of pituitary adenoma--special reference to immunohistochemical study of hormone production].

We have referred 63 cases of pituitary adenoma during past 10 years at department pathology of Hokkaido University Hospital. The mean age at diagnosis was 38 years, with a range from 13 to 73 years. 35 patients complained of non-hormonal sign (head ache, disturbance of vision, disturbance of consciousness, fatigability), 32 patients presented with hormonal sign (acromegaly, troubles of menstruation, galactorrhoea, cushing syndrome) and 7 patients had both signs. Immunohistochemically, GH cell adenoma was 16 cases, Prolactine cell adenoma was 11 cases, ACTH cell adenoma was 4 cases, Non-functioning adenoma was 19 cases and Mixed type was 10 cases.

Adenoma↗
PubMed1989

Electrostatic interaction in the reaction between porphyrin and DNA.

The association of tetrakis(4-N-methylpyridyl)porphine with salmon testes DNA in solution has been investigated in the presence of ethanol at 25 degrees C. It was found that the association constant was 1.14 x 10(6) M-1 and it increased with increasing the mole fraction of added ethanol. The behavior was very different from that in the case of usual intercalaters.

Animals↗
PubMed1989

[A case of acute myeloblastic leukemia associated with multiple intracerebral hematomas].

A case of acute myeloblastic leukemia associated with multiple intracerebral hematomas is presented. A 19-year-old woman with a two week's history of mild fever suddenly lost consciousness, and was afflicted right severe hemiparesis, left mild hemiparesis and motor aphasia. A CT scan revealed bilateral thalamic hyperdense lesions and paraventricular small hematoma in the right hemisphere. Hematology showed marked leukocytosis (450,000/mm3), mild anemia and no coagulopathy including disseminated intravascular coagulation syndrome. Cytology showed myeloblasts with positive stain in peroxidase and negative in esterase both in cerebrospinal fluid and blood. These findings indicated M 1 type, myeloblastic leukemia without maturation, according to FAB (French-American-British Co-operative group) classification. CT scan on the second day demonstrated expansion of the hematoma in the right thalamus, and nine brand-new small hematomas in different locations. The patient deteriorated into brain death soon after this examination. The pathology of this case was supposed to be "hyperleukocytosis", which is defined as a leukocyte count greater than 100,000/mm3. Severe leukostasis due both to dense leukocytes and lack of mobility of the myeloblast brought about an increase in permeability because of local impairment of nutrition to the walls of the vessels. As a result, the following histological changes occurred: 1) cellular exudation into Virchow-Robin space, 2) the appearance of leukemic nodule, admixtures of leukemic cells and erythrocytes, 3) mechanical compression of the capillaries and venules by the enlarging mass of the leukemic nodules. CT scan showed these characteristics as follows: 1) multiplicity, 2) small-size, 3) cerebral hemisphere, especially in white matter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Enterotoxin of Clostridium perfringens type A forms ion-permeable channels in a lipid bilayer membrane.

The enterotoxin of Clostridium perfringens type A was found to form ion-permeable channels in a lipid bilayer. A patch clamp technique was used to detect channel activities in an asolectin bilayer with incorporated enterotoxin. About 20% of the lipid bilayer patches examined showed rectangular or stepwise shift of membrane current. The shifts indicated the gating of ion-permeable channels in the patches. The channels showed high conductance (40-450 pS), no rectification in current-voltage curves and occasional long-lasting events. The significance of these findings is discussed in relation to the mechanism of action of the toxin.

Clostridium perfringens↗
PubMed1988

Kinetics for reaction of a circularized intervening sequence with CU, UCU, CUCU, and CUCUCU: mechanistic implications from the dependence on temperature and on oligomer and Mg2+ concentrations.

The self-splicing intervening sequence from the rRNA precursor in Tetrahymena thermophila produces a covalently closed, circularized form (C IVS). Reaction rates for reverse cyclization (linearization) of C IVS by the covalent addition of the oligoncleotides CU, UCU, CUCU, and CUCUCU have been measured. The dependence of the observed rates on oligomer and Mg2+ concentrations indicates the presence of intermediates that are generated by separate binding steps for both oligomer and Mg2+. Linearization of C IVS by OH- hydrolysis is suppressed in the presence of oligomer, suggesting oligomer binds near the active site. The binding constants derived for CU at 30 degrees C in 1 and 10 mM Mg2+ are 5 X 10(3) and 2.5 X 10(4) M-1, respectively. These are roughly 4 orders of magnitude larger than expected for simple Watson-Crick base pairing. The binding constants derived for UCU, CUCU, and CUCUCU at 30 degrees C in 10 mM Mg2+ are 1.2 X 10(5), 4 X 10(5), and greater than 10(7) M-1, respectively. The free energy increments for binding of UCU and CUCU relative to CU are similar to those expected from a nearest-neighbor model for addition of base pairs. This indicates the factors responsible for the unusually strong binding of CU to C IVS are restricted to two nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗