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Biomedical subjects

T Komiyama

Publications and source records attributed to T Komiyama.

At least 109 records · Page 6Linked to original sources
PubMed1988

[Clinical significance of serial monitoring of short-latency somatosensory evoked potential in head injury with special reference to intracranial hypertension].

Short-latency somatosensory evoked potential (SEP) was serially monitored in head-injured patients and its clinical significance was evaluated in relation to auditory brain stem response (ABR), prognosis and other parameters such as intracranial pressure (ICP). SEP, ABR, and ICP were monitored serially and automatically in 16 patients with acute head injury. Glasgow Coma Scale (GCS) score was equal to or less than 8 in 14 cases. High dose barbiturate therapy was performed in 7 cases and intracranial hematoma was removed operatively in 14 cases. SEP was recorded from C3'or C4'-Fz leads on the lesion side following stimulation of the contralateral median nerve, and the difference between the two potentials (N20, N13) defined as central conduction time (CCT) was followed at a basic time interval of 10-20 min. The patients were divided into 3 groups according to N20 finding and the prognosis of each group was analyzed. The final outcome (assessed 6 months after injury) was graded according to Glasgow Outcome Scale as follows: good (good recovery, moderate disability), poor (severe disability, persistent vegetative state), death (death). Three patients with no CCT change showed good recovery (table, 11). Out of 7 patients with no N20 on admission, 5 died due to severely increased ICP and the prognosis for the other 2 cases was poor. The last group consisted of 6 patients in whom CCT varied during hospitalization. In 3 out of these 6 cases N20 finally disappeared due to increased ICP and they died in the acute stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Comparison of spectral and structural properties of three homologous dimeric proteins.

Spectroscopic and structural properties of three homologous dimeric inhibitors of microbial origin, Streptomyces subtilisin inhibitor, alkaline proteinase inhibitor and plasminostreptin, were discussed by comparing the hydropathy maps, the secondary structure contents obtained from the CD analysis, and the Chou and Fasman prediction. The major process of thermal denaturation of these proteins was the two-step transition. The denaturation temperature dropped in the order Streptomyces subtilisin inhibitor greater than alkaline proteinase inhibitor greater than plasminostreptin. Differences in the denaturation temperature were interpreted in terms of differences in the hydropathy scale of side-chains of the alpha 1-helix of these proteins. The lower CD change upon the complex formation of plasminostreptin with subtilisin BPN' than those with of Streptomyces subtilisin inhibitor and alkaline proteinase inhibitor was explained in terms of the large increase in hydrophilicity of the contact region of plasminostreptin with the enzyme.

Amino Acid Sequence↗
PubMed1986

Human prothymosin alpha: amino acid sequence and immunologic properties.

Prothymosin alpha has been purified from human thymus and its amino acid sequence determined, except for a 15 amino acid segment including 10 glutamyl residues near the middle of the molecule. Like prothymosin alpha from rat thymus [A. A. Haritos, R. Blacher, S. Stein, J. Caldarella, and B. L. Horecker (1985) Proc. Natl. Acad. Sci. USA 82, 343-346], human prothymosin contains the thymosin alpha 1 sequence at its NH2-terminus. It contains a total of 109-110 residues compared to 111-112 for rat prothymosin alpha, with deletions corresponding to positions Gln39 and Lys108 of the rat polypeptide. Human prothymosin alpha also differs from rat prothymosin alpha at positions corresponding to residues 87, 92, and 102 of the latter, with substitutions of alanine for proline, alanine for valine, and aspartic acid for glutamic acid, respectively. Human prothymosin is significantly less active than rat prothymosin in protecting mice against infection with Candida albicans and in stimulating release in vivo of migration inhibitory factor. Thus, the differences in amino acid sequences, present mainly the COOH-terminal half of the polypeptides, may determine species specificity in biological properties.

Amino Acid Sequence↗
PubMed1986

Antigenic specificity of a rabbit antiserum raised against the 15-28 segment of thymosin alpha 1.

Thymosin alpha 1, an acidic 28-residue peptide, enhances immune function. We have described a radioimmunoassay for this thymic factor based on a rabbit antiserum raised against a thymosin alpha 1-(15-28) conjugate (Incefy et al., J. Immun. Meth. 1986, in press). The detailed antigenic specificity of this antiserum was determined by measuring the ability of synthetic segments and analogues of thymosin alpha 1 and related peptides to compete with radioiodinated Ac-Tyr-thymosin alpha 1-(15-28) in this radioimmunoassay. The antiserum bound segments Ac-(1-28), (15-28), (20-28) and (21-28) with nearly equal efficiency but failed to bind segments Ac-(1-10), (11-20), (19-24) and (22-28). Thus, the major immunoreactive site seen by the antiserum is the COOH-terminal segment (21-28) (Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH). Immunoreactivity of (21-28) was nearly abolished when the carboxylate groups of Glu-21, Glu-27 and Asn-28 were omitted separately. The antiserum bound to prothymosin alpha and thymosin alpha 11, which lack the alpha-carboxylate group of Asn-28, with 0.9 and 0.2%, respectively, of the efficiency of thymosin alpha 1. But it bound nonspecifically to parathymosin alpha, which contains the internal segment . . . -Glu-Val-Val-Glu-Glu-Glu-Glu-Asn- . . . . Residues Glu-21, Glu-27 and Asn-28 of thymosin alpha 1 may be important features of the antigenic site through their ability to induce helical structure, through the ability of their negatively charged carboxylate groups to bind to specific sites on the antibody or both.

Amino Acid Sequence↗
PubMed1986

The primary structure of rat parathymosin.

Parathymosin has been isolated from rat thymus and from rat liver. Its primary structure is reported as follows: (Sequence; see text). The blocking group at the NH2 terminus was identified by mass spectrometry as acetyl. Regions homologous to amino acid sequences in prothymosin alpha were found to be located between residues 14-20, 23-25, 33-39, 41-43, and 83-87 of parathymosin.

Amino Acid Sequence↗
PubMed1986

Interactions of anticancer quinone drugs, aclacinomycin A, adriamycin, carbazilquinone, and mitomycin C, with NADPH-cytochrome P-450 reductase, xanthine oxidase and oxygen.

The properties of the interactions of anticancer quinone drugs, aclacinomycin A, adriamycin, carbazilquinone, and mitomycin C with nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P-450 reductase and xanthine oxidase under anaerobic and aerobic conditions were studied. Km values of NADPH-cytochrome P-450 reductase for these drugs were in the range of 40-227 microM, and that of deflavo xanthine oxidase in the range of 39-over 200 microM. Under anaerobic conditions, when xanthine was used as an electron donor, deflavo xanthine oxidase catalyzed the reductive glycosidic cleavage reaction of anthracyclines and nicotinamide adenine dinucleotide was ineffective as an electron donor. In the electron spin resonance study, the formation of the semiquinone or free radical state of the quinone drugs in both enzyme systems were evidenced. A weak and symmetric signal was obtained from aclacinomycin A, and a symmetric signal from adriamycin was changed into an asymmetric and strong. The hyperfine structure was obtained from carbazilquinone in the oxidase system. In the studies of ultraviolet-visible spectra of the quinone drugs in the reductase system, the spectra of aclacinomycin A and adriamycin were changed to their 7-deoxylaglycones, and the formation of small amounts of the fully reduced form were observed after long incubations. The spectrum of carbazilquinone was changed to the hydroquinone form and mitomycin C was converted into mitosene analogues. Under aerobic conditions, superoxide radicals and hydrogen peroxide were effectively produced in the presence of anticancer quinone drugs in both enzyme systems. The superoxide-dependent hydroxy radical production, which was measured by ethylene production from methional, was observed in the presence of aclacinomycin A and adriamycin in the deflavo xanthine oxidase system. From these results, the possible reactions in the interactions of anticancer quinone drugs with these enzymes and oxygen are discussed.

Aclarubicin↗
PubMed1986

EMG-reaction time of the biceps brachii in bilateral simultaneous motions.

EMG-RTs of the biceps brachii muscles were measured using electromyogram (EMG) in elbow flexion and forearm supination on 18 right-and 24 left-handed subjects for four tasks, flexion or supination (symmetrical) and flexion of one and supination of the other side (asymmetrical). For both subject groups, the EMG-RTs of flexion for both hands were not prolonged under asymmetrical tasks, but the EMG-RTs of supination were significantly prolonged on both sides. Comparing the coefficients of determination of the EMG-RTs of flexion to those of supination under four different tasks, those of the preferred hand for symmetrical and asymmetrical motions did not differ, but those of the nonpreferred side for asymmetrical motions were smaller than those for symmetrical motions in both subjects. These observations indicated prolongation of EMG-RT on the asymmetrical task was larger on supination than on flexion. It was suggested that the influence of strong timing constraints was greater on the auxiliary function than on the innate function of the biceps (elbow flexor). The steadiness of motor function of the preferred hand was also discussed in regard to hand preference.

Adolescent↗
PubMed1986

Complex of subtilisin BPN' with Streptomyces subtilisin inhibitor. Complex formation concomitant with change in reducibility of disulfide bonds in the inhibitor.

Structure of the complex of Streptomyces subtilisin inhibitor (SSI) with subtilisin BPN' was studied by examining the thermal denaturation and reducibility of disulfide bonds. The denaturation temperature of the complex was significantly higher than that of the enzyme. Two disulfide bonds localized in the inhibitor side were completely reduced in the complex, whereas only one of them was reduced in the free SSI. Gel filtration of the reduced complex solution showed clearly that the main products of reduction of the complex were two peptide fragments of SSI divided at the active site. The resistive disulfide bond in the complexed inhibitor became accessible as a result of a large conformational change due to splitting of the half-reduced inhibitor.

Bacterial Proteins↗
PubMed1985

Enhanced production of ethylene from methional by iron chelates and heme containing proteins in the system consisting of quinone compounds and NADPH-cytochrome P-450 reductase.

The addition of iron chelates or heme containing proteins to the systems consisting of NADPH-cytochrome P-450 reductase and quinone compounds, such as vitamin K3 (menadione), adriamycin, tetrahydropyranyladriamycin, daunomycin, aclacinomycin A, carbazilquinone, and mitomycin C, showed the enhanced production of ethylene from methional. In the vitamin K3 system, the effective iron chlates were Fe(II)-EDTA, Fe(II)-ADP, Fe(II)-bleomycin A2, and hemin, and the effective iron containing proteins were methemoglobin, myoglobin, ferredoxin, and partially purified cytochromes P-450, P-420, and b5, and the reversed effects were observed by horse radish peroxidase and sulfite reductase from yeast. In the system consisting of aclacinomycin A and methemoglobin, the ethylene production was potently inhibited by radical scavengers, such as Tiron, Tris, thiourea, and KI, and weakly inhibited by some other scavengers. In the system containing vitamin K3 and methemoglobin, the ethylene production was potently inhibited by catalase, but partially by superoxide dismutase, KCN, and NaN3. In this system, the absorption spectrum of methemoglobin was immediately changed to oxyform and quenched with time, and catalase protected the decrement of the spectrum. The addition of hydrogen peroxide or cumene hydroperoxide to methemoglobin also produced ethylene from methional.

Aldehydes↗
PubMed1984

A circular dichroism study on thermal denaturation of a dimeric globular protein, Streptomyces subtilisin inhibitor.

Thermal denaturation of Streptomyces subtilisin inhibitor was studied by means of circular dichroism (CD) measurements in the far-UV and near-UV regions. The denaturation was found to be largely reversible; the partial irreversibility was associated with a slight loss of the inhibitory activity. Difference CD spectra in the far-UV region clarified the existence of two distinct steps in the thermal transition of the secondary structure. The first step below 80 degrees C is attributable to a partial conformational change in the alpha-helix portion, whereas the second step between 80 degrees C and 94 degrees C is attributable to a major conformational change involving the beta-sheet portion. On the assumption that the major denaturation involves dissociation of the SSI into its subunits, the enthalpy and entropy changes were determined to be 216 kcal X mol-1 and to be 603 cal X deg-1 X mol-1, respectively.

Bacterial Proteins↗
PubMed1983

Interaction of new anthracycline antibiotics with DNA. Effects on nucleic acid synthesis and binding to DNA.

The effects of various new anthracycline antibiotics on DNA and RNA synthesis were studied using DNA polymerase I (EC 2.7.7.7), RNA polymerase (EC 2.7.7.6) obtained from Escherichia coli and reverse transcriptase obtained from avian myeloblastosis virus. Aclacinomycin A, its analogues, baumycins A1 and A2, adriamycin and daunomycin showed potent inhibitory effects on these polymerases, with calf thymus DNA as template, with IC50 values of 10-30 microM. With poly(rA) x d(pT)10 as template for reverse transcriptase, aclacinomycin A and daunomycin showed IC50 values higher than 500 microM. Baumycins B1, B2, C1, and C2 showed high IC50 values on three polymerases. Addition of excess template DNA to the reaction mixture reversed the inhibitory effect of anthracyclines. Addition of calf thymus DNA to anthracyclines caused a bathochromic and hypochromic change in the visible spectrum. Apparent binding constant for aclacinomycin A, its analogues, and adriamycin were in the range of (1-2) X 10(6) M-1. Aclacinomycin A and adriamycin also bind to heat denatured DNA, but not strongly to yeast RNA. From these results, the structure-activity relationships of new anthracyclines on DNA binding and polymerase reactions are discussed.

Animals↗
PubMed1982

Generation of hydroxyl radical by anticancer quinone drugs, carbazilquinone, mitomycin C, aclacinomycin A and adriamycin, in the presence of NADPH-cytochrome P-450 reductase.

The generation of hydroxyl free radicals in the system consisting of purified NADPH-cytochrome P-450 reductase and anticancer quinone drugs, such as carbazilquinone, mitomycin C, aclacinomycin A and adriamycin, has been confirmed by two methods. In the spin trapping study, using N-tert-butyl-alpha-phenylnitrone as the spin trapping agent, four drugs generated hydroxyl radical-trapped signals, and the formation of the spin adduct was dependent on time and the enzyme concentration. Among the four drugs, the generation time of signal was in the order of carbazilquinone, aclacinomycin A, adriamycin and mitomycin C, but the magnitude of signal intensity was different. In both aclacinomycin A and adriamycin, the signal disappeared in a few minutes. Catalase completely inhibited the formation of the spin adduct, while superoxide dismutase did not significantly inhibit, but effected in some manner. The generation of hydroxyl radical was also confirmed by the ethylene production from methional. Among the four drugs, the order of the magnitude of ethylene production was different from that of signal intensity by ESR study. Catalase potently inhibited the ethylene production, while superoxide dismutase effected in some manner. From these results, the interactions of anticancer quinone drugs with NADPH-cytochrome P-450 reductase and oxygen, and the possible relations of the enzymes to the radical related actions of these drugs are discussed.

Aclarubicin↗
PubMed1980

Fluorescence quenching as an indicator for the exposure of tryptophyl residues in Streptomyces subtilisin inhibitor.

Fluorescence quenching by acrylamide and trichloroethanol of two equivalent tryptophyl residues in Streptomyces Subtilisin Inhibitor (SSI) was studied in several different conformations of the protein. Fluorescence intensity and polarization degree were simultaneously observed, and the relation between fluorescence intensity and lifetime was examined. The quenching profiles showed deviation from the Stern-Volmer plots. In the denatured form, a nonstoichiometric mechanism which differs from the static and dynamic one was found to be applicable to the interpretation of quenching by acrylamide. Quenching by trichloroethanol proceeds via the nonstoichiometric process for both the native (N) and the denatured (D) form. Each quenching constant obtained from SSI in N- or D-form for acrylamide or trichloroethanol quenching was compared with the others or with that from free tryptophan, as an indicator of the relative exposure of tryptophyl residues. The quenching constant of acrylamide for the urea denatured D-form is larger than that for the acid denatured D-form. The urea denatured state has more exposed tryptophyl residues. Temperature dependence of fluorescence quenching by Cs+ was also studied and a structural fluctuation was found around Trp-86 prior to the massive unfolding of the hydrophobic core containing the residue.

Bacterial Proteins↗