Biomedical subjects

T Inui

Publications and source records attributed to T Inui.

At least 55 records · Page 3Linked to original sources

PubMed2000

Morphological changes and lysis induced by beta-lactams associated with the characteristic profiles of affinities of penicillin-binding proteins in actinobacillus pleuropneumoniae.

Actinobacillus pleuropneumoniae, which was formerly classified in the genus Haemophilus, is a pathogen causing swine pleuropneumonia. We found that aspoxicillin showed strong activity and that meropenem had better lytic activity against this pathogen. In the present study, we for the first time identified penicillin-binding proteins (PBPs) of A. pleuropneumoniae in order to elucidate the relationship between the antibacterial and lytic activities of beta-lactam antibiotics and affinities of the PBPs. The competitive assay using (3)H-labeled benzylpenicillin revealed seven PBPs in A. pleuropneumoniae; they were determined to be PBPs 1a, 1b, 2, 3, 4, 5, and 6, and the molecular masses of these PBPs were estimated to be 92, 80, 76, 72, 50, 44, and 30 kDa, respectively, by comparison with those of Haemophilus influenzae. Our detailed analysis of the affinities of the PBPs of A. pleuropneumoniae and of the bacterial lysis kinetics for several beta-lactam antibiotics revealed that the strong antibacterial activity of aspoxicillin against this strain could be related to the higher affinity of PBP 3 and that preferential inactivation of PBP 1b could cause rapid lysis.

Actinobacillus pleuropneumoniae↗

PubMed2000

Analysis of prognostic and survival factors related to treatment of low-grade astrocytomas in adults.

Prognostic factors for low-grade astrocytomas have been proposed, but optimal treatment remains controversial. Eighty-eight consecutive adult patients with supratentorial low-grade astrocytomas were retrospectively reviewed to determine specific factors influencing outcome. All underwent craniotomy (43 radical resections, 45 nonradical resections). Sex, age at diagnosis, preoperative Karnofsky performance status (KPS), tumor location, estimated extent of resection, radiation, chemotherapy, histological type, p53 status, MIB-1 staining and the apoptotic index were assessed as parameters for prognostic significance. KPS (p = 0.03), tumor location (p < 0.001), extent of surgical resection (p < 0.001) and radiotherapy (p = 0.01) were significantly associated with longer survival rates by univariate analysis. Multivariate analysis also showed a significant correlation between radiation therapy after surgical removal and survival time (p < 0.001). p53 status was not of importance in determining the necessity for radiotherapy. Radical surgical removal is the most important factor in the management of low-grade astrocytomas. Radiation therapy appears to be effective in improving the prognosis regardless of the extent of surgical resection or the p53 status.

Adult↗

PubMed2000

Effect of polymethylene and phenylene linking groups on the DNA cleavage specificity of distamycin-linked hydroxamic acid-vanadyl complexes.

Two types of distamycin-linked hydroxamic acids (DHA), which contain various lengths of polymethylene chains (PM-DHA) and relatively rigid phenylene ones (Ph-DHA), have been synthesized for the first time. Their DNA cleavage specificities were investigated by an end-labeled fragment cleavage experiment in the presence of vanadyl ion and hydrogen peroxide. The DNA cleavage by the PM-DHA x VO(II) complexes was shown to be very dependent on the length of the chain and the AT sequences. The tetramethylene DHA (1b) complex exhibited highly specific cleavage patterns flanking the 8 and 10 AT sites. Interestingly, the Ph-DHA complexes selectively cleaved the 5' end-labeled strand at the AT sites, but did not cleave the 3' end-labeled strand. The vanadyl complexing moieties and the local sequence conformation of the AT tract are suggested to contribute significantly to the DNA recognition of the PM-DHA x VO(II) complexes.

Animals↗

PubMed2000

[Psychological complexity of the figures and properties of retention in visual short-term memory].

We investigated how the physical variables of complex figures had effects on psychological complexity and recognition of complex figures. Complexity was objectively defined by the amount of convex parts and Perimeter/square root of Area (P/square root of A), which varied with both the number of convex parts and the length of one convex part. In complexity judgments the results showed that the judged complexity was not well predicted by P/square root of A, and that the amount of convex parts rather than P/square root of A had much influence on the judged complexity. In a recognition experiment, the results showed that performance was dependent on both the number of convex parts and the length of one convex part when P/square root of A was held constant. When P/square root of A was low and constant, performance tended to deteriorate with increasing the amount of convex parts. But when P/square root of A was high and constant, performance peaked at a convex parts value of 8, and deteriorated at higher or lower values of convex parts. The results indicated that both the number of convex parts and the length of one convex part were effective in deteriorating retention in visual short-term memory, and that P/square root of A had indirect influence on performance.

Adult↗

PubMed1999

Enhancement of lipocalin-type prostaglandin D synthase enzyme activity by guanidine hydrochloride.

The characterization of unfolding of mouse recombinant lipocalin-type prostaglandin D synthase (L-PGDS) by guanidine hydrochloride (GdnHCl) was carried out. In the presence of low concentrations of GdnHCl (up to 0.75 M), enhancement of the enzyme activity was observed. However, above a 1 M concentration of GdnHCl, the enzyme activity was reduced in a concentration-dependent manner. The maximum enzyme activity induced by GdnHCl was approximately 1. 5-fold compared with the activity under physiological conditions without GdnHCl. The ellipticity in circular dichroism (CD) spectrum of the L-PGDS at 218 nm, reflecting the beta-sheet content, was decreased by GdnHCl (up to 0.75 M), and the minimum ellipticity was observed at 0.5 M GdnHCl. The fluorescence quenching of the intrinsic tryptophan of L-PGDS due to the binding of bilirubin in the presence or absence of GdnHCl was measured. The K(d) values obtained in the presence and absence of 0.5 M GdnHCl were 447 and 115 nM, respectively, indicating lower affinity of the L-PGDS for bilirubin with GdnHCl than without it. Further, an NMR study revealed that the reorganization of hydrogen-bond network in the L-PGDS was observed in the presence of 0.5 M GdnHCl. These results, taken together, indicate that the enzyme activity of L-PGDS is enhanced by the conformational change, especially by the change in the secondary structure.

Animals↗

PubMed1999

The role of the posterior parietal cortex in human object recognition: a functional magnetic resonance imaging study.

The mechanisms involved in visual object recognition from non-canonical viewpoints were investigated using functional magnetic resonance imaging (fMRI). We used a passive observation task and found three areas activated more strongly in the non-canonical viewing condition compared with the canonical viewing condition. First, it was found that the fusiform gyrus and posterior part of the inferior temporal cortex were involved in the processing of shape information. Next, it was found that the posterior parietal cortex, mainly the superior parietal lobule and the ventral part of premotor area were involved in visuospatial processing and accessing sensorimotor knowledge. These results may indicate that recognition from non-canonical viewpoints is supported by using functional properties of the object, which require more real-time processing for object manipulation.

Adult↗

PubMed1999

Structure-activity relationships of calcicludine and dendrotoxin-I, homologous peptides acting on different targets, calcium and potassium channels.

Calcicludine (CaC) and dendrotoxin-I (DTX-I) possess high homology of their primary structures despite their different biological activities acting on calcium and potassium channels, respectively. In order to elucidate the channel specificity displayed by these toxins, their three-dimensional structures were compared by NMR. These analyses revealed that their overall conformations are similar except for the structure at the N-terminus. To demonstrate the significance of this N-terminal, chimeric peptides, CaC(1-30)/DTX-I(31-60) and DTX-I(1-30)/CaC(31-60), were synthesized. The CD spectra and receptor-binding measurements of chimeric peptides indicated that the contribution to the overall conformation and to the affinity of the N-terminal part of molecule seem to be more important than that of the C-terminal one. These results suggest that the N-terminal part may participate in distinguishing between calcium and potassium channels.

Amino Acid Sequence↗

PubMed1999

Matrix metalloproteinases and lysosomal cysteine proteases in osteoclasts contribute to bone resorption through distinct modes of action.

The effects of inhibitors of matrix metalloproteinases (MMPs) and lysosomal cysteine proteases on osteoclastic pit formation in dentine slices were investigated. A nonspecific cysteine protease inhibitor, E-64, inhibited pit formation on naked slices in a concentration-dependent manner, and at 10 microM E-64 reduced the pit volume by 70%. However, up to 10 microM of the MMP inhibitor, BB-94, did not show any inhibition of pit formation. On the other hand, on slices coated with reconstituted basement membrane, both BB-94 and E-64 at 10 microM showed a marked decrease in pit volume by 73% and 68%, respectively. By a combination of treatment with both BB-94 and E-64, pit formation could be completely suppressed. These results suggest that MMPs are necessary for the migration of precursor and/or immature osteoclasts to bone surface through basement membranes, while cysteine proteases are essential for the osteoclastic degradation of bone collagen.

Animals↗

PubMed1999

A functional magnetic resonance imaging study of listening comprehension of languages in human at 3 tesla-comprehension level and activation of the language areas.

Passive listening comprehension of native and non-native language was investigated using high resolution functional magnetic resonance imaging (fMRI) at a static magnetic field strength of 3 tesla. Wernicke's area was activated by comprehensive and non-comprehensive languages indicating that this area is associated with common phonological processing of language. The task with comprehensive but non-native language activated Broca's area and angular gyrus most frequently. The activations in these areas may be related to demand in semantic and syntactic processing in listening comprehension. Supplementary motor area and pre-motor area were activated by comprehensive languages but not by non-comprehensive language. These motor controlling areas may be involved in semantic processing. Listening to comprehensive but non-native language seems to demand more networked co-processing.

Adult↗

PubMed1999

Polyethylene glycol augments thyroid cAMP responses by fragments from protease-digested TSAb or TSBAb-IgG.

In the previous reports, we have demonstrated (1) that polyethylene glycol (PEG)(5%) augmented TSAb (thyroid stimulating antibody)-stimulated cAMP responses of porcine thyroid cells, and (2) that fragments from papain-digested TSBAb (thyroid stimulation blocking antibody) could stimulate thyroid cAMP synthesis. Thus, we studied the effect of 5% PEG on cAMP responses stimulated by the protease-digested TSAb- or TSBAb-fragments. Stimulatory effect of 5% PEG on cAMP production by Fab fragment (Mr 50 KDa) and the retarded fraction (Mr 20 KDa) from the gel-filtration on Sephadex G-100 using papain-digested TSAb-IgG unbound to Protein A-Sepharose was observed. Similar stimulatory effect of 5% PEG on the second fraction (Fc with trace amounts of Fab) in the gel-filtration on Sephadex G-100 using papain digested TSAb-IgG bound to Protein A-Sepharose was observed. Stimulatory effect of PEG on the second fraction was derived from Fab fragment. PEG (5%) also showed stimulatory effect on cAMP production by F(ab')2 fragment (Mr 100 KDa) from the gel-filtration on Sephadex G-100 using pepsin-digested TSAb-IgG unbound to Protein A-Sepharose. PEG (5%) augmented cAMP responses by both Fab and the retarded fractions from the gel-filtration using papain-digested TSBAb-IgG unbound to Protein A when these fractions could stimulate cAMP synthesis. In conclusion, PEG (5%) augments cAMP responses stimulated by F(ab')2, Fab and the smaller molecular components (Mr 20 KDa) separated from protease-digested TSAb-IgG. PEG also augments cAMP responses stimulated by Fab and the smaller molecular components with thyroid stimulating activity separated from papain-digested TSBAb-IgG.

Autoantibodies↗

PubMed1999

Computational analysis of disparity modulation sensitivity: an explanation in terms of a Bayesian surface reconstruction.

Sensitivity to binocular disparity modulation has been shown to have a bandpass nature. This paper presents a computational account for the disparity modulation function (DMF) in terms of a Bayesian surface reconstruction. The Bayesian approach suggests that prior assumptions about surface structure will affect the perception of disparity modulation. Taking into account a prior constraint of surface smoothness being imposed on the perceived surfaces, we propose that computing the first derivatives of the surfaces determines the bandpass shape of the DMF. Based on this idea, we derive an analytical prediction of the DMF. It is then shown that the prediction gives a good fit to the empirical data. Implications for possible mechanisms underlying the DMF are discussed.

Depth Perception↗

PubMed1999

Selective activation of excitation-contraction coupling pathways by ET(A) and ET(B) receptors in guinea-pig tracheal smooth muscle.

1. Signalling events responsible for endothelin(A) (ET(A)) and ET(B) receptor-induced contraction were examined in epithelium-denuded guinea-pig tracheal smooth muscle strips. Selective stimulation of each subtype was achieved by a combination of ET-1 (100 nM) and ET(A) and ET(B) receptor-selective antagonists, BQ-123 (10 microM) and BQ-788 (3 microM), respectively. 2. Both ET(A) and ET(B) receptors induced long-lasting contraction that was totally dependent on Ca2+ influx. Stimulation of ET(A) receptor induced both transient and sustained (Ca2+)i increases whereas that of ET(B) receptor induced only a sustained increase. Suppression of the transient (Ca2+)i increase by U73122 (3 microM) did not affect the ET(A)-induced sustained (Ca2+)i increase and tension development. Stimulation of ET(A) receptor, but not ET(B), induced phosphoinositide breakdown and protein kinase C (PKC). The activated PKC contributed to the contraction by increasing the Ca2+ sensitivity of the contractile apparatus. 3. Thus, ET(A) receptor is coupled both with phospholipase C/Ca2+/PKC signalling and Ca2+ influx pathways whereas ET(B) receptor was coupled only with the latter. 4. Stimulation of ET(B) receptor, but not ET(A), caused membrane depolarization measured with a fluorescent indicator, bis-(1,3 dibutylbarbituric acid)-trimethine oxonol. Both nifedipine (1 microM) and verapamil (10 microM) abolished ET(B)-induced Ca2+ influx and contraction, while they barely affected ET(A)-induced responses. 5. Therefore, the Ca2+ influx pathways activated by each subtype appeared to be completely different; ET(A) and ET(B) receptors opens voltage-independent Ca2+ channels and L-type voltage-dependent Ca2+ channels, respectively.

Animals↗

PubMed1999

Effect of prophylactic administration of hyperimmune plasma to prevent Rhodococcus equi infection on foals from endemically affected farms.

The effect on foals of prophylactic administration of hyperimmune plasma to prevent R. equi infection was investigated on three farms at which R. equi infection was endemic. Sixteen foals between 10 and 39 days of age were intravenously given 1-21 of hyperimmune plasma. ELISA antibody titres against R. equi were significantly increased and maintained at high levels for over 30 days in most of the recipient foals. The prevalence of R. equi infection was 6.3% (1/16) in the foals that received the immune plasma, and 26.3% (5/19) in the control foals not given the immune plasma on the three farms. For 2 years before and after this field trial on the three farms, 18 of 64 foals (28.1%) showed clinical signs of respiratory tract infection and four of them died of R. equi pneumonia. Heavy contamination of horses and their environment with virulent R. equi was detected by colony blotting, and plasmid profiles also suggested that foals on the three farms were constantly exposed to virulent R. equi. The results of this field trial support previous observations by some researchers that the administration of hyperimmune plasma to foals in the early days of life promotes prevention of R. equi infection on endemic farms; however, the mechanism of hyperimmune plasma protection remains unclear.

Actinomycetales Infections↗

PubMed1999

Mechanism of the augmentative effect of high polyethylene glycol (PEG) concentrations on the thyroid stimulating activity in TSAb-IgG using a porcine thyroid cell assay.

We previously demonstrated that high polyethylene glycol (PEG) concentrations (5% PEG) significantly augmented cAMP production in response to TSAb-IgG using the porcine thyroid cell (PTC) assay. The mechanism of the stimulatory effect of 5% PEG on cAMP production was examined by a two-step incubation with PTC. TSAb-IgG was preincubated with or without addition of 5% PEG in the PTC assay for 2.5 hr (1st incubation) and separated PTC was re-incubated with fresh Hank's buffer for 5 hr (2nd incubation). cAMP production in the 1st incubation medium by co-incubation of TSAb-IgG and 5% PEG for 2.5 hr was significantly increased (3.3-fold) compared to that without 5% PEG. When the cAMP content in PTC and the incubation medium were compared in the same volume of incubation medium after co-incubation of TSAb-IgG and 5% PEG for 2.5 hr, cAMP contents in PTC were about 7-fold higher than that in the incubation medium, and this ratio did not change in the incubation medium of TSAb-IgG without 5% PEG. Similar increases in cAMP contents in PTC (6.6-fold) compared to the incubation medium were also observed with bTSH, although there was no augmentative effect of 5% PEG on cAMP production by bTSH in either the incubation medium or PTC. When PTC, which had been preincubated with normal-IgG and 5% PEG in the 1st incubation, was re-incubated with TSAb-IgG in the 2nd incubation medium, cAMP production by TSAb-IgG was not stimulated by 5% PEG. The augmentative effect of 5% PEG on cAMP production by TSAb-IgG was observed whenever 5% PEG and TSAb-IgG were co-incubated in either the 1st or 2nd incubation. However, no stimulatory effect of 5% PEG on bTSH was observed. These results suggested the stimulatory effect of 5% PEG on TSAb-IgG-stimulated cAMP production may be due to the increase of binding or incorporation of TSAb-IgG into the membranes of PTC compared to TSH.

Animals↗

PubMed1999

Augmentation of thyroid-stimulating antibody-stimulated cyclic adenosine monophosphate response by polyethylene glycol, polyvinyl alcohol, and dextran; highly sensitive porcine thyroid cell thyroid-stimulating antibody assay.

Previously, we reported that 5% polyethylene glycol (PEG) (6000) augmented thyroid-stimulating antibody (TSAb)-stimulated cyclic adenosine monophosphate (cAMP) production in porcine thyroid cell (PTC) assay. This augmentation by PEG was specific to TSAb-stimulation. In this study we examined the effects of nonionic hydrophilic polymers such as PEG, polyvinyl alcohol (PVA), and dextran (DEX) on TSAb-stimulated cAMP production. We demonstrated that graded doses of PEG, PVA, and DEX augmented TSAb-stimulated cAMP productions; the prominent augmentations were observed with 5% PEG (20,000), 5% PEG (6000), 6% PEG (4000), 10% PVA, 14% DEX T-250, and 14% DEX T-70. PVA did not augment thyrotropin (TSH)-stimulated cAMP synthesis. Five percent PEG (20,000), 14% DEX T-250, and 14% DEX T-70 augmented TSH-stimulated cAMP synthesis very slightly. PEG, PVA, and DEX had no effects on the cAMP synthesis stimulated by GTPgammaS, forskolin, or pituitary adenylate cyclase activating polypeptide (PACAP), which stimulated adenylate cyclase. We also demonstrated that PEG, PVA, and DEX augmented the cAMP responses stimulated by small amounts (50 microL) of sera from Graves' patients; small amounts (50 microL) of sera could be used instead of purified immunoglobulin G (IgG). This may simplify the TSAb assay. We developed a highly sensitive simplified TSAb assay. PEG weakly augmented TSAb binding to isolated TSH receptor (thyrotropin-binding inhibitor immunoglobulin [TBII] increased slightly). The mechanisms of the augmentations of TSAb-stimulated cAMP productions by PEG, PVA, and DEX is not simply explained by increased binding of TSAb to the receptors. Some factors that enhance TSAb action at the receptor site are suggested.

Animals↗

PubMed1999

DNA alterations in human oral squamous cell carcinomas detected by restriction landmark genomic scanning.

Genetic abnormalities in human oral squamous cell carcinomas (OSCC) were examined using restriction landmark genomic scanning (RLGS), a method of two-dimensional gel analysis allowing detection of amplifications and other aberrations in genomic DNA. DNAs from 11 oral tumours as well as from contiguous normal squamous epithelium, were cleaved with the restriction enzyme Not I, [32p] end-labeled and electrophoretically size-fractionated. Following a second digestion employing Hinf I, the further fragmented DNA was again electrophoretically separated. Five fragments/spots were found amplified in at least 64% (7/11) (chromosome nos. 4, 9-12 or 22) of carcinomas, with one of these spots amplified in 100% (chromosome no. 4) of tumour samples. In addition, six other spots were frequently reduced in at least 55% (chromosome nos. 15 or 9-12) of tumour tissues. Further characterization of these common changes is needed to determine if they represent important alterations in OSCC.

Carcinoma, Squamous Cell↗

PubMed1999

Potent bacteriolytic activity of ritipenem associated with a characteristic profile of affinities for penicillin-binding proteins of Haemophilus influenzae.

Ritipenem is highly bacteriolytic against Haemophilus influenzae. Bacterial lysis was shown after treatments with ritipenem and cefsulodin at their MICs and after treatments with fropenem and cefdinir at four times their MICs, indicated by decreases in the culture turbidities and by morphological changes of the destroyed cells. These beta-lactams were preferentially bound to penicillin-binding protein (PBP) 1b. Ritipenem, fropenem, and cefsulodin exhibited poor affinities to PBPs 3a and 3b, but cefdinir showed high affinities to these PBPs. Microscopic examinations revealed that selective PBP 3 inhibitors, such as aztreonam and cefotaxime, inhibited lysis induced by ritipenem. These results suggest that the preferential inactivation of PBP 1b could be essential to induce the lysis of H. influenzae cells and that binding to PBPs 3a and 3b may interfere with lysis.

Bacterial Proteins↗

PubMed1999

Clinical usefulness of TSAb assay with high polyethylene glycol concentrations.

We previously demonstrated the stimulatory effect of polyethylene glycol (PEG) on thyroid-stimulating antibody (TSAb)-IgG-stimulated cAMP production (thyroid stimulating (TS) index) in porcine thyroid cell (PTC) assay. In the present study the clinical usefulness of the practical method using high PEG concentrations was examined. TS activity using PEG 22.5% precipitated fraction (PF) was significantly higher compared to standard TSAb activity using 12.5% PF from TSAb-positive serum, but the maximum TS activity was observed with PEG 12.5% PF + 4% PEG or PEG 22.5% PF + 2% PEG. In all cases of untreated Graves' patients, TSAb activity determined by PEG 22.5% PF was higher compared to standard TSAb activity using PEG 12. 5% PF from test serum, but the highest TSAb activity was observed by PEG 12.5% PF + 4% PEG without increased cAMP production to normal serum. TSAb was positive in 85% (40/47), 98% (46/47) and 100% (47/47) of untreated Graves' patients by the method of PEG 12.5% PF, PEG 22.5% PF and PEG 12.5% + 4% PEG, respectively. Increased TSAb activity by PEG 12.5% PF + 4% PEG method was also observed even if the standard TSAb activity using PEG 12.5% PF method was negative in the euthyroid states of Graves' patients during antithyroid drug therapy. The stimulatory effect of PEG on TS activity was not found in other thyroidal diseases [thyroiditis chronica (with high serum TSH), thyroid stimulation-blocking antibody (TSBAb)-positive sera (with low serum TSH), adenomatous goiter, subacute thyroiditis, and thyroid cancer]. The stimulatory effect of 5% PEG on TS activity produced directly by small amounts of Graves' serum (50 microl) was also found, although the sensitivity was lower than with PEG-precipitated IgG from 0.2 ml serum. The clinical usefulness of the sensitive TSAb assay using PEG-precipitated IgG or direct serum assay in the presence of high PEG concentrations was demonstrated.

Biological Assay↗