Search PubMed⌕ Search

Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 73 records · Page 4Linked to original sources
PubMed2000

Characterization of the cryptic plasmid pSBO2 isolated from Streptococcus bovis JB1 and construction of a new shuttle vector.

A cryptic plasmid designated pSBO2 (3582 bp) was isolated from Streptococcus bovis JB1. The pSBO2 contained putative sites for a double-strand origin (dso), a small transcriptional repressor protein (Cop), countertranscribed RNAs (ctRNAs), and a replication protein (Rep), which were similar to those from pMV158 and pLS1, which were isolated from S. agalactiae, and pWVO1, isolated from Lactococcus lactis. The putative single-strand origin (sso) of pSBO2 was similar to pER341 and pST1, which were isolated from S. thermophilus. Recombinant plasmid designated pSBE2 was constructed to bind pECM184 vector and the DNA fragment containing sso, dso, Cop, ctRNAs, and Rep of pSBO2. When pSBE2 was introduced into S. bovis 12-U-1 and no8, the plasmids in the transformants had deleted the 160-bp fragment between sso and dso. This plasmid, designated pSBE2A, was capable of transforming Escherichia coli and S. bovis strains 12-U-1 and no8 on high frequency; therefore, pSBE2A is an effective shuttle vector.

Amino Acid Sequence↗
PubMed2000

Phenotypic characterization of polysaccharidases produced by four Prevotella type strains.

Four ruminal Prevotella type strains, P. ruminicola JCM8958T, P. bryantii B 4T, P. albensis M384T, and P. brevis ATCC19188T, were characterized for polysaccharide-degrading activities with the reducing sugar release assay and zymogram analyses. Carboxymethylcellulase, xylanase, and polygalacturonate (PG)-degrading enzyme activities were determined in cultures grown on oat spelt xylan, xylose, arabinose, cellobiose, and glucose as sole growth substrates. P. ruminicola and P. albensis showed carboxymethylcellulase induction patterns. When xylan was supplied as a sole growth substrate, xylanase activities produced by P. bryantii and P. albensis were at least 18- and 11-fold higher, respectively, than during growth on other carbohydrates, suggesting that the regulation of the xylanases was highly specific to xylan. All strains constitutively produced PG-degrading enzymes. The corresponding activity of P. bryantii was more than 40-fold higher than in other strains. Zymogram analyses routinely detected the presence of high-molecular-weight (100-170 kDa) polysaccharide-degrading enzymes in ruminal Prevotella. Characteristics of the polysaccharide-degrading activities showed diversity of ruminal Prevotella species.

Animals↗
PubMed2000

The Double-Water-Film Electrode: A Device for Measuring the Resistance and the Capacitance of the Internode/Node Interface of Chara as Functions of Time and Temperature.

A "double-water-film electrode technique" has been developed for the long-term characterization of the electrical properties across the interface between the nodal (N) and internodal (A or B) cells and the vacuole along the length of an internode of Chara as a function of time and temperature. The electrode unit consisted of a pair of the water-film electrodes described elsewhere (Chilcott 1988; Chilcott and others 1983; Coster and others 1984; Lucas 1985; and Ogata 1983). The distance between two water-film probes was fixed at 1.0 cm. By scanning the electrode unit, the spatial variations in electrical resistance and capacitance along the longitudinal axis of Chara were observed. Analysis was performed by applying an electrical equivalent circuit for the biomembrane (Philippson 1921). Across the internode (-A or -B)/central nodal cells interface, the specific parallel resistance (Rm) and the parallel capacitance (Cm) at 20 degrees C were 30 +/- 5 x 10(-3) Omegam(2) and 1.5 +/- 0.5 x 10(-1)Fm(-2) (at 30 Hz), respectively. And the series resistance, corresponding to the vacuole of the internode was 8 x 10(-3) Omegam(2). Study of temperature dependencies of Rm and Cm suggested that a dynamic homeostatic regulation was operating at the interface where numerous plasmodesmata were observed with an electron microscope (Pickett-Heaps 1967; Spanswick and Costerton 1967). Assuming that the individual cylinder of plasmodesma was filled only with cytoplasm, the number of plasmodesma per interface was estimated at 2.6 x 10(5).

Journal Article↗
PubMed2000

An automatic homology modeling method consisting of database searches and simulated annealing.

We introduce a method of homology modeling consisting of database searches and simulated annealing. All processes involving searches for homologous proteins, alignment, the construction of Calpha atoms, construction of main-chain atoms, and the construction of side-chain atoms are performed automatically. In this method, main-chain conformations are generated from the weighted average of mainchain coordinates in reference proteins. The weight is defined by the local space homology representing the similarity of environmental residues at topologically equivalent positions in reference proteins. Side-chain conformations are generated for constructed main-chain atoms by database searches, and main-chain atoms are optimized for the fixed side-chain conformations. These two processes, i.e., the side-chain generation and main-chain optimization, are repeated several times. This type of construction provides a structure similar to the x-ray structure, in particular, for main-chain and side-chain atoms in the residues belonging to structurally conserved regions (SCRs). The accuracy of our method was evaluated for 14 proteins whose structures are known. The average root mean square deviation between models and x-ray structures was 2.29 A for all atoms, and the percentage of chi1 angles within 30 degrees was 72.6% for SCRs residues. Some models were in good agreement with their respective x-ray structures. Our method, which has the advantage of being automated, gives results similar to, or better than, published results for three widely used test proteins. Our software, FAMS, is available on the World Wide Web.

Amino Acid Sequence↗
PubMed2000

Flow cytometric assessment of CD15+CD117+ cells for the detection of minimal residual disease in adult acute myeloid leukaemia.

There is little information available regarding immunophenotypic monitoring of minimal residual disease (MRD) in acute myeloid leukaemia (AML). We investigated leukaemic cells co-expressing CD15 and CD117 (CD15+CD117+) in 72 adult AML cases at diagnosis. In 22 cases (31%) with various AML subtypes, more than 5% of leukaemic cells showed the CD15+CD117+ phenotype (range 5.22-55.48%). These 22 cases were younger and had a higher complete remission (CR) rate than the other AML cases, but the CD15+CD117+ cell percentage at diagnosis showed no correlation with the CR duration among the 72 cases. The CD15+CD117+ cell percentage showed a range of 0.00-0.08% in bone marrow cells from 10 haematologically normal subjects. We also investigated CD15+CD117+ cells in sequential bone marrow samples from 17 AML patients who achieved CR and who had had more than 5% CD15+CD117+ leukaemic cells at diagnosis. Because the CD15+CD117+ cell percentage varied among these AML cases, we calculated the percentage of MRD ¿MRD% = [CD15+CD117+ cells (%) in each sequential marrow sample] / [CD15+CD117+ cells (%) at diagnosis of the corresponding case] x 100¿. A high MRD% after 10 months of CR was significantly associated with a short CR duration (P = 0.0004), whereas continuation of a well-reduced MRD% was associated with a long CR duration. The leukaemic cells conserved the CD15+CD117+ phenotype in all of the eight cases who relapsed. Flow cytometric monitoring of CD15+CD117+ cells is simple and can be applied to a substantial fraction of AML cases. This monitoring may be useful for predicting relapse of adult AML.

Adult↗
PubMed2000

Some properties and the possible role of intrinsic ATPase of rat liver 80S ribosomes in peptide bond elongation.

The properties and role in peptide elongation of ATPase intrinsic to rat liver ribosomes were investigated. (i) Rat liver 80S ribosomes showed high ATPase and GTPase activities, whereas the GTPase activity of EF-1alpha and EF-2 was very low. mRNA, aminoacyl-tRNA, and elongation factors alone enhanced ribosomal ATPase activity and in combination stimulated it additively or synergistically. The results suggest that these translational components induce positive conformational changes of 80S ribosomes by binding to different regions of ribosomes. Translation inhibitors, tetracyclin and fusidic acid, inhibited ribosomal ATPase with or without elongational components. (ii) Two ATPase inhibitors, AMP-P(NH)P and vanadate, did not inhibit GTPase activities of EF-1alpha and EF-2 assayed as uncoupled GTPase, but they did inhibit poly(U)-dependent polyphe synthesis of 80S ribosomes. (iii) Effects of AMP-P(NH)P and ATP on poly(U)-dependent polyphe synthesis at various concentrations of GTP were examined. ATP enhanced the activity of polyphe synthesis even at high concentrations of GTP, suggesting a specific role of ATP. At low concentrations of GTP, the extent of inhibition by AMP-P(NH)P was very low, probably owing to the prevention of the reduction of the GTP concentration. (iv) Vanadate inhibited the translocation reaction by high KCl-washed polysomes. These findings together indicate that ribosomal ATPase participates in peptide translation by inducing positive conformational changes of mammalian ribosomes, in addition to its role of chasing tRNA from the E site.

Adenosine Triphosphatases↗
PubMed2000

Backbone dynamics of the c-Myb DNA-binding domain complexed with a specific DNA.

The DNA-binding domain of c-Myb consists of three imperfect tandem repeats, R1, R2, and R3. Each repeat contains three helices. The minimal DNA-binding domain is an R2R3 fragment. Here, we have examined the backbone dynamics of R2R3 in its DNA-bound form by NMR. Upon binding to DNA, the N- and C-termini, and the linker between R2 and R3 become less flexible. In the free form the third helix of R2 exhibits slow conformational exchange fluctuations owing to a cavity in the hydrophobic core of R2. Upon binding to DNA, the conformational exchange contributions in R2 are reduced but remain significant in NMR relaxation measurements. Upon binding to DNA, the third helix of R3 comes to exhibit significant chemical exchange contributions. These findings suggest that the orientations of the third helices of both R2 and R3 as to DNA are being chemically exchanged. In the DNA-bound form both R2 and R3 exhibit similar dynamical characters, except for amino acids Trp 95, Thr 96, and Val 103 of R2, which are located around the cavity of the unbound form. Upon binding to DNA, since Trp 95 moves into the cavity to fill it up, the local conformational exchange contributions seem to be still observable around the filled cavity.

Amino Acid Sequence↗
PubMed2000

An ATPase center of rat liver 30S-5SRNP particles.

Treatment of 30S-5SRNP with 1 M Cs(2)SO(4) at 2 degrees C overnight followed by sucrose density-gradient centrifugation yielded particles smaller than 30S-5SRNP, designated as CsS-particles. CsCl density-gradient centrifugation of CsS-particles showed the homogeneity of the particles containing about half the amount of proteins in 30S-5SRNP particles. The particles contained 18SrRNA, 5SRNP and about half the number of proteins in 30S-5SRNP. The ATPase activity of freshly prepared CsS-particles was about half the original 30S-5SRNP level although it was unstable even at 2 degrees C. Poly(U) slightly enhanced the activity, and phe-tRNA(phe) stimulated it concentration-dependently. EF-1a alone enhanced it, and in combination with poly(U) and phe-tRNA(phe) stimulated it markedly. EF-2 alone markedly increased it. The activity with the full components for elongation described above became very high, being comparable to that of the original 30S-5SRNP and twice that of 40S subunits. A two-dimensional electrophoretogram of the protein in CsS-particles revealed 9 small subunit protein species, in addition to L5, which included proteins interacting with mRNA and two elongation factors. Taken together with the results of our preceding study indicating the participation of ATPase of 80S ribosomes in peptide elongation, the present results indicate CsS-particles may be a part of the ATPase centre of 80S ribosomes.

Adenosine Triphosphatases↗
PubMed2000

Studies on ATPase(GTPase) intrinsic to E. coli ribosomes.

(1) Escherichia coli 70S ribosomes showed intrinsic ATPase and GTPase activities, although they were much lower than those of rat liver ribosomes. The latter activity was higher than the former one. (2) The ATPase activity was inhibited by GTP and GMP-P(NH)P, and the GTPase activity was inhibited by ATP and AMP-P(NH)P, indicating a close relationship between the two enzymes. (3) Elongation components alone or in combination enhanced the ATPase activity, indicating the possible correlation of ribosomal ATPase with elongational components. (4) Vanadate at the concentrations that did not inhibit the GTPase activities of EF-Tu and EF-G, depressed the poly(U)-dependent polyphe synthesis, suggesting that ribosomal ATPase (GTPase) participates in peptide elongation by inducing positive conformational changes of ribosomes required for the attachment of elongational components.

Adenosine Triphosphatases↗
PubMed2000

Effects of a cane on floor reaction force and center of force during gait.

In comparative studies of various gait patterns of 20 healthy subjects who used a cane, the vertical reaction forces and the center of force on the foot were measured and recorded by a force recording and analyzing device. The results indicated that when a cane was used in the ipsilateral hand, the center of force did not shift significantly compared with normal gait. When a cane was used in the contralateral hand, the center of force shifted medially compared with normal gait. In analysis of the vertical floor reaction force acting on the foot, the most efficient way to use a cane was to control the pacing so that the tip of the cane and the foot touched the ground simultaneously. By doing so, the cane could share as much as 34.3% of force at heel strike, 25.3% at midstance, and 29.7% at toeoff of the stance phase of the gait cycle. When prescribing use of a cane for a patient with varus gonarthritis, the patient should be instructed to use the cane in the ipsilateral hand so as not to shift the center of force medially; for a patient with valgus gonarthritis, the cane should be used in the contralateral hand to shift the center of force medially. Patients should be taught to control pacing so that the tip of the cane and the foot touch the ground simultaneously.

Canes↗
PubMed2000

[Influenza virus surveillance in Tama, Tokyo--viral examinations in 1996/97, 1997/98, 1998/99, and 1999/2000 seasons].

During the 1996/97, 1997/98, 1998/99, and 1999/2000 seasons, isolations of influenza virus and/or confirmations of hemagglutinin gene of virus from the throat swab of patients in 9 medical institutions in Tama, Tokyo were carried out by RT-PCR and tissue culture with MDCK cells. In 1996/97 and 1997/98 seasons, type A (H3N2) was the predominant type of influenza virus, which was 85% in the 1996/97 and 97% in the 1997/98, but small-scale outbreaks with type B virus was also confirmed in the 1996/97 season (during the 8th and 10th week). On the other hand, in the other two seasons, 2 different kinds of types of virus were discovered, which was type A (H3N2) and type B in 1998/99 season, and H3N2 and H1N1 of type A virus in 1999/2000 season. In the 1998/99 season, type A (H3N2) prevailed in the first half, and type B gradually replaced type A (H3N2) after the 5th week in 1999, whereas 2 different kinds of type A in the 1999/2000 mixed during the outbreak. From the presented data, the difference of mode by age groups and year could be explained. Namely, most specimens and positive cases in 1996/97 and 1997/98 seasons were those from low age groups (fifteen years of age and below). In 1998/99 and 1999/2000 seasons, the number of specimens from high age groups (sixteen years of age or over) accounted for above 50%, and about 70% of type A (H3N2)-positive cases. Contrary, the frequency of type B virus in 1998/99 season and type A (H1N1) in 1999/2000 season was higher in the low age groups than the high ones.

Hemagglutination, Viral↗
PubMed2000

Effect of thrombopoietin on proliferation of blasts from patients with myelodysplastic syndromes.

Thrombopoietin (TPO), a major cytokine involved in megakaryocytopoiesis/thrombopoiesis, may be effective for treatment of the thrombocytopenia associated with myelodysplastic syndromes (MDS). However, it has been unclear whether TPO stimulates proliferation of MDS blasts, as observed in de novo acute myeloid leukemia. This study examined this concern. When marrow cells from 37 MDS cases were cultured with or without recombinant human PEGylated TPO, TPO increased the blast number (stimulation index > or =1.5) in 9 of 16 high-risk MDS cases (refractory anemia with excess blasts [RAEB] and RAEB in transformation) and 4 of 10 cases with MDS transformed to acute leukemia (MDS-AL), but none of 11 cases with low-risk MDS (RA and RA with ringed sideroblasts). When the cell cycle of cultured cells was determined by three-color flow cytometry, TPO activated the cell cycle of MDS cells (causing a decrease in G(0)-phase cells) in most of the cases whose blast number increased in response to TPO. Reverse transcriptase-polymerase chain reaction analysis detected TPO receptor messenger RNA in purified blasts from all six cases examined, irrespective of the response of their blasts to TPO in culture. Analysis of the patients' characteristics identified a high-serum lactate dehydrogenase (LDH) value as being associated with blast proliferation in high-risk MDS cases (p = 0.0036). We conclude that TPO stimulates in vitro proliferation of blasts from a fraction of MDS patients. High-risk MDS patients, especially those who have a high-serum LDH value, and MDS-AL patients should be monitored with particular care in clinical trials of TPO for MDS.

Adult↗
PubMed2000

[Psychiatric distress and related risk factors of family caregivers who care for the demented elderly at home].

The objectives of our study were to assess psychiatric distress of caregivers who had been caring for the demented elderly at home and to examine the association of caregivers' psychiatric distress with putative risk factors. Subjects were 294 caregivers living in Amakusa, Kumamoto Prefecture of Japan, whose spouses, parents or other family members were registered at Amakusa Public Health Center as demented elderly. In 1998, Survey on Caregivers' Mental Health was conducted using the General Health Questionnaire (GHQ12) as a measurement for general psychiatric state of caregivers. Two hundred and eighty-two caregivers responded to interviews with complaints of the following psychological symptoms: feelings of unhappiness (55.7%), of stress (41.8%), insomnia (29.4%) and depressed mood (29.1%). Seventy-six caregivers (27.2%) were identified as being above the cut-off point 4 for psychiatric distress caseness. Multivariate logistic regression analysis indicated caregivers' psychiatric distress was statistically associated with caregivers' age, the caregivers' perception of the severity of dementia, the number of years devoted to caregiving at home and perceived financial state. Being 50 to 69 years (OR = 0.37, 95% CI: 0.17-0.81) and being 70 years or older (OR = 0.35, 95% CI: 0.14-0.83) were negatively associated with caseness as compared to being 20 to 49 years. Caseness was positively related to the severity of the elderly's demented state (OR = 6.93, 95% CI: 1.99-24.19), 1 year to 2 years devoted to caregiving at home (OR = 3.26, 95% CI: 1.02-10.38), no family or social support (OR = 2.99, 95% CI: 1.12-7.96) and lower perceived financial state (always OR = 6.99, 95% CI: 2.77-17.64, sometimes OR = 2.41, 95% CI: 1.19-4.85). Reduction of caregivers' psychiatric distress is important for not merely the enhancement of quality of care for demented elders and caregivers' life but for the prevention of elder abuse or neglect. Our study suggests that a comprehensive assessment and intervention program is needed for the demented elderly and their caregivers, in order for caregivers to be able to adapt well to the challenges of caregiving and find personal meaning through caregiving.

Aged↗
PubMed2000

Low proportion of G0-phase cells during induction chemotherapy correlates with subsequent remission in acute myeloid leukemia.

Kinetic resistance is assumed to be one of the main mechanisms of drug resistance in acute myeloid leukemia (AML), but the relationship between cell cycle status at diagnosis and achievement of complete remission (CR) is controversial. Based on the possibility that the cell cycle data after starting induction chemotherapy are more important than the pretreatment data, we used 3-color flow cytometry to examine the cell cycle (G0, G1, S, and G2/M phases) of AML cells on days 0, 5, and 9 of the first induction chemotherapy in 20 patients. Cell cycle data at these 3 time points were compared in the patients who achieved CR (CR cases) and in the patients who had persistent leukemia (non-CR cases) after the induction chemotherapy. In the CR cases, there was a tendency for the percentages of G0-phase AML cells on days 5 and 9 to be smaller than that on day 0, while the opposite tendency was observed in the non-CR cases. When cell cycle data were compared between the CR and non-CR cases, the percentage of G0-phase AML cells on day 9 differed significantly (CR cases 6.9% +/- 10.9%, non-CR cases 50.1% +/- 38.4%; P = .0024). This significance remained when the patients' AML subtype was taken into consideration. None of the other cell cycle data at each time point or the hematologic parameters, which may be related to CR achievement, showed differences between the CR and non-CR cases. We emphasize the importance of cell cycle analysis after initiating therapy and suggest that such analysis can identify refractory AML subjects. The identified subjects may be candidates for clinical trials of cell cycle modulators.

Acute Disease↗
PubMed2000

[MVP for MR associated with extensive calcification of the mitral valve annulus].

We experienced two surgical cases of MR associated with extensive calcification of the mitral valve annulus. For two cases we performed MVP which consisted of valve repair and annular remodeling. Annular remodeling was performed only on the annulus without calcification using 3 mm Gore-tex graft, because calcified annulus did not contribute to annular dilatation and would not dilate in the future. Both patients recovered uneventfully. Postoperative echocardiography revealed no MR in both cases.

Aged↗
PubMed2000

Thrombopoietin and myelodysplastic syndromes.

Thrombopoietin (TPO), a major cytokine involved in megakaryocystopoiesis/thrombopoiesis, may be effective for the treatment of thrombocytopenia associated with myelodysplastic syndromes (MDS). We reviewed the available data relating to the therapeutic potential of TPO for MDS and found the following. The endogenous TPO level is elevated in MDS patients, especially in those with refractory anemia (RA). In RA patients, but not in patients with RA with excess blasts (RAEB) or RAEB in transformation (RAEB-t), both the platelet and megakaryocyte counts correlate inversely with the endogenous TPO level. This scenario indicates that the physiological mechanism for regulating the endogenous TPO level is conserved, at least in part, in RA patients. The number of TPO receptors (TPO-R) expressed on platelets and CD41+ and/or CD34+ cells in MDS is reduced to nearly half the number present in normal subjects. This is consistent with the finding that TPO-induced in vitro megakaryocytopoiesis is not uniformly observed in MDS. Meanwhile, in some patients with RAEB, RAEB-t, or chronic myelomonocytic leukemia, blasts have the TPO-R mRNA and probably TPO-R protein. This fact may explain the lack of correlation between the endogenous TPO level and the platelet and megakaryocyte counts in RAEB and RAEB-t and suggests that TPO may induce blast proliferation in some cases. These findings may be of use when designing a clinical trial of TPO for MDS.

Anemia, Refractory↗
PubMed1999

A small cryptic plasmid from Ruminobacter amylophilus NIAH-3 possesses functional mobilization properties.

The complete nucleotide sequence of a small cryptic plasmid designated pRAO1, from the Gram-negative ruminal bacterium Ruminobacter amylophilus NIAH-3, was determined. The plasmid is a circular DNA molecule, 2140 bp in size, with a GC content of 40%. Computer-assisted analysis identified three open reading frames (ORFs), one of which, ORF3 (347 amino acids), displayed a high degree of amino acid identity with the Mob proteins involved in conjugative mobilization and interplasmid recombination of plasmids from Gram-positive bacteria. We proved the mobilization properties of pRAO1 in the Escherichia coli system using the coresident IncW broad-host-range conjugative plasmid R388. These data demonstrated, for the first time, the mobilization properties of small cryptic plasmids from Gram-negative inhabitants of the rumen.

Amino Acid Sequence↗