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Biomedical subjects

M Iwama

Publications and source records attributed to M Iwama.

At least 73 records · Page 4Linked to original sources
PubMed1989

Stabilization of blood platelet microtubular system by staurosporine.

The stimulative effects of phorbol myristate acetate (PMA) on rabbit platelet shape change and platelet adhesion were completely inhibited by staurosporine (STS)-pretreatment. When the platelets were observed by whole mount immuno transmission electron microscopy (TEM), STS was found to stabilize platelet microtubular cytoskeleton. Electrophoretic analysis of the isolated marginal bundles of cytoskeleton after STS-PMA treatment revealed a newly formed 200 K high molecular weight protein band accompanied with heavy losses of tubulin monomers. These bundles of STS-treated platelets as observed in immuno TEM responded poorly to the anti alpha- or beta-tubulin antibody as compared with those of the control platelets. The results suggest that sts favour the specific assembly of tubulin bundles with a possible involvement of the microtubular associated proteins (MAPs). The resultant tight marginal bundles (MB) of cytoskeleton will stabilize the platelets and resist the effects of exogeneously added stimulants such as PMA.

Alkaloids↗
PubMed1989

Primary structure of a ribonuclease from bullfrog (Rana catesbeiana) liver.

A pyrimidine base-specific ribonuclease was purified from bullfrog (Rana catesbeiana) liver by means of CM-cellulose column chromatography and affinity chromatography on heparin-Sepharose CL-6B, which gave single band on SDS-slab electrophoresis. The primary structure of the bullfrog liver RNase was determined. It consisted of 111 amino acid residues, including 8 half-cystine residues. From the sequence, it was concluded that three disulfide bridges in RNase A were conserved in the bullfrog RNase, that a disulfide bridge in RNase A [Cys65-Cys126 (RNase A numbering)] was deleted, and that a new disulfide bridge was created in the C-terminal part of the enzyme. In this frog RNase, the amino acid residues thought to be essential for catalysis in bovine pancreatic RNase A were conserved except for Asp121 (RNase A numbering). The sequence homology of the bullfrog liver RNase with bovine pancreatic RNase A was 30.6%. The sequence of bullfrog liver RNase was very similar to those of lectins obtained from bullfrog egg by Titani et al. [Biochemistry (1988) 26, 2189-2194] and R. japonica egg by Kamiya et al. [Seikagaku (in Japanese) (1989) 60, 733; and personal communication from Kamiya, Y., Oyama, F., Oyama, R., Sakakibara, F., Nitta, K., Kawauchi, H., and Titani, K.]. The sequence homology between the bullfrog liver RNase and the two lectins was 70.2 and 64.8%, respectively.

Amino Acid Sequence↗
PubMed1989

[Brain stem projections of afferent fibres form the salivary gland].

The sensory nerve fibres and terminals exist in the salivary gland. However, the projection sites of these sensory fibres have not been clarified. The present study was examined electrophysiologically the projection site of the afferent fibres in the brain stem in urethane-chloralose anesthetized cats. The sensory fibres from the sublingual and submandibular glands were passing through the trigeminal nerve. The afferent fibres projected to the caudal end of subnucleus interpolaris of trigeminal spinal tract nucleus, then send the secondary neurons to the lateral and medial of bulbar reticular formation and pontine reticular formation. The sensory afferents from the salivary gland would control the salivary secretion and other autonomic functions.

Afferent Pathways↗
PubMed1989

[Reset of masticatory rhythm evoked by stimulation of the cortical masticatory area].

The rhythmical jaw movement can be evoked by repetitive electrical stimulation of the cortical masticatory area in various animals. However, the relationship between evoked jaw movement and each stimulus pulse applied to the cortical masticatory area has not been clarified. The present study examined the effects of each stimulus pulse for evoked masticatory rhythm in urethan anesthetized rabbits. The repetitive electrical stimulation applied to the cortical masticatory area not only evoked rhythmic jaw movement but reset the rhythmic cycle. The application of stimulus pulses till about 70 msec after starting point of the cycle in 4.1 Hz stimulation and till 50 msec in 8.2 Hz stimulation did not reset the cycle length. After these non resetting time, the first stimulus pulse reset the cycle length, and the following any stimulus pulse did not reset the cycle length. When the stimulus pulse reset the cycle length, the length from the applied point of stimulus to the end of cycle was stable: about 184 msec in 4.1 Hz stimulation and 199 msec in 8.2 Hz stimulation. Therefore, the length of basic cycle would be about 250 msec (184 msec + 70 msec = 254 msec in 4.1 Hz stimulation, 199 msec + 50 msec = 249 msec in 8.2 Hz stimulation). This basic cycle length coincided with the shortest cycle length of the rhythmical jaw movement evoked by the most effective stimulation of the cortical masticatory area.

Animals↗
PubMed1988

Amino acid sequence of the nonsecretory ribonuclease of human urine.

The amino acid sequence of a nonsecretory ribonuclease isolated from human urine was determined except for the identity of the residue at position 7. Sequence information indicates that the ribonucleases of human liver and spleen and an eosinophil-derived neurotoxin are identical or very closely related gene products. The sequence is identical at about 30% of the amino acid positions with those of all of the secreted mammalian ribonucleases for which information is available. Identical residues include active-site residues histidine-12, histidine-119, and lysine-41, other residues known to be important for substrate binding and catalytic activity, and all eight half-cystine residues common to these enzymes. Major differences include a deletion of six residues in the (so-called) S-peptide loop, insertions of two, and nine residues, respectively, in three other external loops of the molecule, and an addition of three residues at the amino terminus. The sequence shows the human nonsecretory ribonuclease to belong to the same ribonuclease superfamily as the mammalian secretory ribonucleases, turtle pancreatic ribonuclease, and human angiogenin. Sequence data suggest that a gene duplication occurred in an ancient vertebrate ancestor; one branch led to the nonsecretory ribonuclease, while the other branch led to a second duplication, with one line leading to the secretory ribonucleases (in mammals) and the second line leading to pancreatic ribonuclease in turtle and an angiogenic factor in mammals (human angiogenin). The nonsecretory ribonuclease has five short carbohydrate chains attached via asparagine residues at the surface of the molecule; these chains may have been shortened by exoglycosidase action.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1988

Primary structure of a non-secretory ribonuclease from bovine kidney.

The primary structure of a non-secretory ribonuclease from bovine kidney (RNase K2) was determined. The sequence determined was VPKGLTKARWFEIQHIQPRLLQCNKAMSGV NNYTQHCKPENTFLHNVFQDVTAVCDMPNIICKNGRHNCHQSPKPVNLTQCNFIAGRYPDC RYHDDAQYKFFIVACDPPQKTDPPYHLVPVHLDKYF. The sequence homology with human non-secretory RNase, bovine pancreatic RNase, and human secretory RNase are 46, 34.6, and 32.3%, respectively. The bovine kidney RNase has two inserted sequences, a tripeptide at the N-terminus and a heptapeptide between the 113th and 114th position of bovine pancreatic RNase; on the other hand, it is deleted of the hexapeptide consisting of the 17th to the 22nd amino acid residue of RNase A. The amino acid residues assumed to be the constituents of the bovine pancreatic RNase active site are all conserved except F120 (L in RNase K2).

Amino Acid Sequence↗
PubMed1985

Alterations in glycosaminoglycans of the aorta of vitamin E-deficient rats.

To elucidate whether or not a vitamin E-deficient diet affects the rat aorta extracellular matrix, we examined the alterations in glycosaminoglycans (GAGs), as one of the components of the extracellular matrix of the aorta. The total amount of uronic acid, as an index of GAG, decreased significantly in the aorta of vitamin E-deficient rats. The components of GAG were identified as hyaluronic acid (HA), heparan sulfate (HS), dermatan sulfate (DS) and chondroitin sulfate (CS) by electrophoresis together with enzymic digestion. The amount of sulfated GAGs, especially the amount of DS and CS, decreased in the aorta of vitamin E-deficient rats. The biosynthetic activity of GAG was determined by using [3H]glucosamine and [35S]sulfate. The total biosynthetic activity of GAG and the incorporation of [3H]glucosamine into HA, HS, DS and CS decreased markedly in the aorta of vitamin E-deficient rats. The decrease in the production of sulfated GAGs, especially DS, which is involved in the potent antithrombogenic activity, could be related to the lower anticoagulant activity in the aorta of vitamin E-deficient rats.

Animals↗
PubMed1985

Modification of a minor glucoamylase from Aspergillus saitoi with 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide metho p-toluenesulfonate.

In order to elucidate the structure-function relationship of glucoamylases [EC 3.2.1.3, alpha-D-(1-4)-glucan glucohydrolase] from Aspergillus saitoi, the reaction of a minor component, Gluc M2 with 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide metho p-toluenesulfonate (CMC) was studied at pH 4.5. Inactivation of Gluc M2 with [14C]CMC proceeded with the incorporation of about 5 CMC moieties. From the results of analyses of amino acid and sulfhydryl contents of CMC-modified Gluc M2 and the hydroxylamine treatment of the CMC-modified Gluc M2 at pH 7.0, it was concluded that the sites of CMC-modification were carboxylic acids of Gluc M2. In the presence of maltose, when Gluc M2 was treated with [14C]CMC, ca. 4 CMC moieties were incorporated with a simultaneous decrease in activity (30%). The Gluc M2 modified in the presence of maltose was re-modified with CMC after elimination of maltose. The CMC-modified Gluc M2 (70% activity) was inactivated completely with the further incorporation of ca. 2 CMC moieties. The logarithm of the half-life of the inactivation of Gluc M2 by CMC was a linear function of log[CMC] indicating that one carboxyl group among the modified ones was crucial for the inactivation of Gluc M2. From the results of these modification reactions, it was concluded that one or two carboxylic acids in Gluc M2 were crucial for the catalysis of glucoamylase from A. saitoi. Based on the analysis of the pH-profile of CMC inactivation of Gluc M2, the participation of a carboxylic acid having pKa 5.7 in the active site is proposed.

Amino Acids↗
PubMed1985

Modification of a ribonuclease from Rhizopus sp. with 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide p-toluenesulfonate.

The carboxyl group in a ribonuclease from Rhizopus sp. (RNase Rh) was modified by a water-soluble carbodiimide, 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide p-toluenesulfonate (CMC). From the relation between the extent of modification and the enzymatic activity, it was concluded that at least the modification of two carboxyl groups seemed to induce the loss in enzymatic activity. In the presence of 1 M cytidine, RNase Rh activity was protected from the CMC-modification. Under conditions in which the enzyme was inactivated to 20% activity, about 70% of the enzymatic activity was retained in the presence of cytidine. The inactivation of the RNase Rh pre-treated with CMC in the presence of cytidine with [14C]CMC indicated that the RNase Rh lost its enzymatic activity with the incorporation of about one [14C]CMC. Therefore, it could be concluded that one carboxyl group is involved in the active site of RNase Rh. The binding of the CMC-modified RNase Rh with 2'-AMP was studied spectrophotometrically. The affinity of the modified RNase Rh towards 2'-AMP decreased markedly upon CMC modification.

Adenosine Monophosphate↗
PubMed1985

Inhibition of glucoamylases from a Rhizopus sp. and Aspergillus saitoi by aminoalcohol derivatives.

The mechanism of inhibition of the two glucoamylases from a Rhizopus sp. and Aspergillus saitoi by aminoalcohol derivatives was investigated. Hydrolysis of maltose by the glucoamylases was inhibited competitively by aminoalcohols at pH 5.0, and tris(hydroxymethyl)aminomethane, 2-amino-2-ethyl-1,3-propanediol and 2-aminocyclohexanol were relatively good inhibitors of the glucoamylases among the aminoalcohol derivatives tested. One hydroxyl group and an amino group in these inhibitors were indispensable for the inhibitory action, and the addition of other hydroxyl, amino or ethyl groups was enhancing. With an increase in pH from 4.0 to 6.0, the Ki values of the aminoalcohols decreased. This result suggested the participation of a carboxyl group, which was related to the glucoamylase activity and had a pKa of 5.7, in the binding of aminoalcohols. The UV difference spectra induced on binding of the aminoalcohol analogues with the glucoamylases may indicate a change of the environment of tryptophan residues to a slightly higher pH on inhibitor binding. The influence of aminoalcohols on the fluorescence intensity due to tryptophan residues and the CD-spectra of the glucoamylases was less than that of maltitol. Thus, the interaction of aminoalcohols with tryptophan residues in the glucoamylases might be less pronounced than that in the case of substrate analogues. The modes of binding of the aminoalcohols with the two glucoamylases were very similar. Therefore, the phenomenon might be a common feature of glucoamylases in general.

Amino Alcohols↗
PubMed1985

[Anti-inflammatory activity of the dry distillation tar of delipidated soybean (Glyteer) (1)].

The anti-inflammatory activity of the dry distillation tar of delipidated soybean (GL, 0.1 approximately 10%) was investigated by its topical application to mice, rats and guinea pigs; and the effects were compared with those of betamethasone 17-valerate (BV, 0.12%), ibuprofen (IP, 5%), phenylbutazone (PB, 5%) and flufenamic acid (FA, 5%), which were all prepared with the same ointment base. GL (1 approximately 10%) showed a concentration-dependent inhibition of the increased vascular permeability induced by histamine and bradykinin in guinea pigs. GL significantly inhibited rat paw edema induced by carrageenin, but in serotonin-induced paw edema, GL showed only a weak effect. GL also inhibited the erythema formation induced by ultra-violet rays, and the activity was equal to that of PB. The inhibitory potency of GL against the erythema formation induced by arachidonic acid in guinea pigs was equal to that of IP. It is suggested from these results that the mode of action of GL is similar to that of other acidic non-steroidal anti-inflammatory drugs. However, GL did not inhibit paper disk granuloma in rats. Furthermore, GL markedly inhibited the delayed-type hypersensitivity induced by picryl chloride, and the activity was stronger than that of IB, PB and FA. Here GL showed the mode of action seen with steroidal anti-inflammatory drugs. The present data provide evidence that GL applied externally possesses a potent effect as an anti-inflammatory drug.

Administration, Topical↗
PubMed1985

[Central alveolar hypoventilation as a complication of massive intracerebellar hemorrhage: report of a case treated by diaphragm pacing].

The author reported a case of central alveolar hypoventilation (Ondine's curse) which was treated by diaphragm pacing. A 59-year-old man was admitted because of sudden deep coma and tetraparesis. Neurological examination on admission showed miotic pupils with absent light reaction, no oculocephalic reflex, no corneal reflex and tetraparesis. Glasgow scale was evaluated to be E-1 V-1, and M-3 with total of 5 points. Computed tomography confirmed a large hematoma in the cerebellum with ventricular rupture. Immediately, a suboccipital craniectomy was performed and the hematoma was evacuated. His neurological condition was improved gradually within a month after the operation. He responded to verbal orders and moved all his limbs against gravity. His respiration, however, was irregular with a pattern of so-called "cluster breathing" followed by prolonged apnea, that was more pronounced in night. He was suffered from hypoxic hypercapnea and recurrent pneumonia. Therefore, authors decided to employ diaphragm pacing for management of central alveolar hypoventilation. A diaphragm pacemaker (radiofrequency induction) was implanted. A cuff electrode was put around the right phrenic nerve in the right thorax, and the receiver installed subcutaneously in the right anterior chest. Postoperative respiratory study showed ventilation on pacing with satisfactory blood gas and he became able to move around using a wheel chair. In 1966 Glenn demonstrated a new technique to move the diaphragm paced by a receiver through the phrenic nerve, triggered by radio wave from external device.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebellar Diseases↗
PubMed1984

Modification of glucoamylases from Rhizopus sp. with 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide.

To investigate the role of carboxyl groups of glucoamylases [EC 3.2.1.3] from a Rhizopus sp. (Gluc1 and Gluc2), the modification of Gluc1 and Gluc2 with a water-soluble carbodiimide, 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide metho-p-toluenesulfonate (CMC), was studied. The inactivation of Gluc1 proceeded with the incorporation of about 3 CMC moieties. In the presence of maltose, the modification of about 2.2 carboxyl groups of Gluc1 proceeded with a slight loss of enzymatic activity. In the re-modification of Gluc1 modified in the presence of maltose, Gluc1 was inactivated by further modification of about 1.3 carboxyl groups. Therefore, one carboxyl group, which was protected by maltose, was thought to be a crucial one. The inactivation of Gluc2 proceeded similarly to that of Gluc1, but the number of CMC moieties incorporated was about one less than in the case of Gluc1. Thus, it was suggested that one of the reactive carboxyl groups of Gluc1 was located in the N-terminal part of Gluc1, which is deficient in Gluc2. From the results of kinetic studies on CMC-modified Gluc1, it was suggested that the hydrolysis mechanism of malto-oligomers differs somewhat from that of PNPG.

CME-Carbodiimide↗
PubMed1983

Radioimmunoassays for two types of human urinary ribonucleases: differential determination of ribonucleases in human serum.

We developed radioimmunoassays for two types of human urinary ribonucleases. The assays are sensitive, reproducible and specific. One human urinary ribonuclease (RNase UL) showed strong immunological identity with human pancreatic ribonuclease, and the other ribonuclease (RNase Us) showed strong immuno cross-reactivity with human liver ribonuclease. There was no immuno cross-reactivity between these two urinary ribonucleases. Serum immunoreactive RNase UL was eluted as four peaks on phosphocellulose chromatography, whereas immunoreactive RNase US was eluted as a single peak. Serum content of immunoreactive RNase UL was 354 +/- 105 ng/ml (mean +/- SD) in normal individuals, and that of immunoreactive RNase Us was 15.9 +/- 5.7 ng/ml (mean +/- SD). No correlation was demonstrated between these two ribonuclease contents in serum.

Adult↗
PubMed1983

Modification of a major ribonuclease from Aspergillus saitoi with 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide.

In order to investigate the role of carboxyl groups of a base non-specific ribonuclease from Aspergillus saitoi [EC 3.1.27.1] (RNase M, molecular weight 36,000), the modification of RNase M with a water-soluble carbodiimide, 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide(CMC), was studied. The inactivation of RNase M proceeded almost linearly with the incorporation of about 9.5 CMC moieties. The peptide backbone structure of the modified RNase M was practically the same as that of the native RNase M, as assessed from the CD spectra in the region of 200-250 nm. In the presence of competitive inhibitors, adenosine, and cytidine, inactivation of RNase M by CMC was partially inhibited. In the presence of cytidine (1 M), the modification of about 4 carboxyl groups of RNase M proceeded with a slight loss of enzymatic activity (ca. 20%). Further modification inactivated RNase M with the incorporation of ca. 4-5 CMC without any detectable intramolecular peptide bond formation. Therefore, it was concluded that carboxyl groups responsible for enzymatic activity were included among these carboxyl groups protected by cytidine. The logarithm of the half-live of the inactivation of RNase M by CMC was a linear function of log[CMC] with a slope of minus one, indicating that at least one carboxyl group among the modified ones may be essential for catalysis. The digestion of CMC-modified RNase M with carboxypeptidase A eliminated the carboxyl terminal group from the site of CMC modification.

Amides↗
PubMed1983

Alterations of glycosaminoglycans synthesized by chick embryo cartilage treated with 6-amino-nicotinamide.

Treatment of day-4 chick embryos with 6-aminonicotinamide (6-AN) impairs limb chondrogenesis and produces micromelia. However, treatment of day-10 chick embryos with 6-AN does not produce micromelia. In the present study, the glycosaminoglycan (GAG) biosynthesis in the cartilage isolated from the day-10 chick embryos treated with 6-AN in vitro and in the cartilage from the day-11 chick embryos treated with 6-AN in ovo at day-10 was examined. In the epiphyseal cartilage treated in vitro, the radioactivity incorporated into the GAG fraction was significantly decreased and the 35S/3H ratio in the GAG fraction and the molecular size of GAG chain were also decreased. However, the percent distribution of delta Di-0S was almost unchanged. In the epiphyseal and diaphyseal cartilage treated in ovo at day-10, the alteration in GAG biosynthesis was not observed except the reduction of the molecular size of GAG in epiphyseal cartilage. Furthermore, the biosynthetic activity of GAG in the process of recovery/repair was also examined using the micromelial cartilage isolated from day 11-chick embryos given 6-AN in ovo at day-4. In the diaphyseal cartilage, the radioactivity incorporated into the GAG fraction and the 35S/3H ratio were increased, whereas the percent distribution of delta Di-0S was almost unchanged. These results indicate that treatment of day-4 chick embryos with 6-AN produces the rebound phenomena in the diaphyseal cartilage isolated at day-11.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Aminonicotinamide↗
PubMed1983

Limb deformity induced in chick embryo by hydroxyurea.

After a dose of 800 micrograms of hydroxyurea (HU) was administered to day-4 chick embryos in ovo, the limb deformity including micromelia was observed. We examined the teratogenic mechanism of the action for HU by using histochemical and biochemical techniques. The present study provides histological evidence for the cell death and the depression of cell proliferation just after the treatment with HU and the retardation in periosteal ossification during the process of repair and/or recovery from cell death. On the other hand, the incorporation of [3H]glucosamine and [35S]sulfate into glycosaminoglycan was inhibited at day-7 and day-9, when the embryos are in the process of repair and/or recovery. The cartilage specific proteoglycan, an index of chondrogenesis, appeared at day-7, but the ratio of cartilagenous proteoglycan/noncartilagenous proteoglycan in the treated limbs was depressed. These results suggest that the slight retardation in chondrogenesis and/or the incomplete function of chondrocyte were induced by the treatment with HU in chick embryos. It is considered from above observation that the retardation in chondrogenesis and osteogenesis caused during the repair and/or recovery process of cell death brought about the limb deformity; shortening, thinning and bending of hind limbs.

Animals↗