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Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 235 records · Page 13Linked to original sources
PubMed1994

Interleukin-6 and erythropoietin act as direct potentiators and inducers of in vitro cytoplasmic process formation on purified mouse megakaryocytes.

Mouse megakaryocytes were purified using a rabbit antimouse platelet serum, and magnetic beads were conjugated with an antirabbit IgG antibody. The purified cells were 95.8 +/- 1.2% megakaryocytes, and the recovery and viability of the megakaryocytes were 70 +/- 18.4%, and 80 +/- 13.4%, respectively. The effects of recombinant erythropoietin (Epo), interleukin-6 (IL-6), and IL-1 beta on these purified megakaryocytes were studied. Epo and IL-6 significantly increased DNA synthesis in these cells, but IL-1 beta did not. Similarly, both Epo and IL-6, but not IL-1 beta, increased the acetylcholinesterase (AchE) activity in the megakaryocytes. Epo and IL-6 stimulated the megakaryocytes to form cytoplasmic processes, which are considered to represent in vitro proplatelet formation. This process formation was inhibited by the addition of colchicine to the cultures. It was concluded that Epo and IL-6 are not only direct potentiators of megakaryocytes, but also inducers of in vitro cytoplasmic process formation on megakaryocytes.

Acetylcholinesterase↗
PubMed1993

Sexual dimorphism in the trigeminal motor neurons innervating the mouse masseter muscle.

The extrafusal and intrafusal muscle fibers in the masseter muscle are innervated by motoneurons in the trigeminal motor nucleus (Mo 5). In the present study, we found that the number of trigeminal motor neurons in the male mouse was significantly larger than that in the female. However, we could not detect any significant difference between male and female mice in the number of sensory neurons in the trigeminal mesencephalic nucleus (Me 5). This is the first report on sexual dimorphism in masticatory motoneurons of mammals.

Animals↗
PubMed1993

Recognition of specific DNA sequences by the c-myb protooncogene product: role of three repeat units in the DNA-binding domain.

The DNA-binding domain of c-Myb consists of three homologous tandem repeats of 52 amino acids. The structure of the third (C-terminal) repeat obtained by NMR analysis has a conformation related to the helix-turn-helix motif. To identify the role of each repeat in the sequence recognition of DNA, we analyzed specific interactions between c-Myb and DNA by measuring binding affinities for systematic mutants of Myb-binding DNA sites and various truncated c-Myb mutants. We found that specific interactions are localized unevenly in the AACTGAC region in the consensus binding site of c-Myb: The first adenine, third cytosine, and fifth guanine are involved in very specific interactions, in which any base substitutions reduce the binding affinity by > 500-fold. On the other hand, the interaction at the second adenine is less specific, with the affinity reduction in the range of 6- to 15-fold. The seventh cytosine involves a rather peculiar interaction, in which only guanine substitution abolishes the specific binding. The binding analyses, together with the chemical protection analyses, showed that the c-Myb fragment containing the second and third repeats covers the AACTGAC region from the major groove of DNA in such an orientation that the third repeat covers the core AAC sequence. These results suggest that the third repeat recognizes the core AAC sequence very specifically, whereas the second repeat recognizes the GAC sequence in a more redundant manner. The first (N-terminal) repeat, which covers the major groove of DNA only partially, is not significant in the sequence recognition, but it contributes to increase the stability of the Myb-DNA complex. The presence of an N-terminal acidic region upstream of the first repeat, which is important for the activation of c-myb protooncogene, was found to reduce the binding affinity by interfering with the first repeat in binding to DNA.

Base Sequence↗
PubMed1993

High-performance liquid chromatographic determination of histatins in human saliva.

A simple method for the assay of histatins in human saliva by high-performance liquid chromatography has been developed. The histatins in saliva were extracted with 0.1 M HCl-methanol, and histatins 1, 3, 5, and 6 were separated and concentrations were determined by reversed-phase chromatography. This simple method enabled the determination of levels of individual histatins from the saliva of normal subjects. The average concentration of histatins 1, 3, 5, and 6 in parotid saliva collected from 26 healthy volunteers aged from 20 to 30 years were 11.25 +/- 5.65, 8.15 +/- 3.08, 7.67 +/- 3.12, and 1.56 +/- 0.53 mumol/l (mean +/- S.D.), respectively.

Adult↗
PubMed1993

Thermal stability of the DNA-binding domain of the Myb oncoprotein.

The DNA-binding domain of the c-myb protooncogene product consists of three homologous tandem repeats of 51-52 amino acids (denoted as R1, R2, and R3 from the N-terminal side). In order to analyze conformational and thermodynamic characteristics of the homologous repeats, we have examined the DNA-binding domain by circular dichroism (CD) and differential scanning calorimetry (DSC). The CD spectra for the three individual repeats are significantly different in the fine profiles, indicating subtle differences in their conformations. The melting analyses for the fragments show that the thermal stability of each fragment is different from one another, with the following order of stability: R1(Tm = 61 degrees C) approximately greater than R3(57 degrees C) >> R2(43 degrees C), where R2 is much less stable than the other repeats. The denaturing process for the whole DNA-binding domain, measured by DSC, is characterized by a very broad transition ranging from 30 to 80 degrees C. The denaturation curve can be fit well by a three-state transition with one intermediate state. The transition temperature for the native-to-intermediate transition coincides with the melting temperature of R2, indicating that the intermediate state corresponds to the unfolding of unstable R2. The CD spectrum of the whole domain is almost identical to the sum of the individual spectra. Thus, these results suggest that the individual repeats in the whole DNA-binding domain behave independently in terms of conformation and stability. The addition of DNA to the DNA-binding fragment drastically changed the melting profile, in which the broad transition curve was replaced by a sharp peak at 58 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Metabolic characteristics of rat liver cytosolic 5SRNA.

5SRNA were purified from the cytosol, ribosomes, nucleoli and nucleoplasm of rat liver. The 5'-terminal and 3'-terminal sequences of these 5SRNA species were shown to be the same. The time course of changes in specific activities of these 5SRNA in rat liver, 20 min to 16 h after intraperitoneal injection of [14C]orotic acid, were investigated. The specific activity of cytosolic 5SRNA increased almost linearly for 3 h, without a lag, to a high value, then decreased rapidly. The specific activity of cytosolic 5SRNA was much higher than the specific activities of 5SRNA from the other cellular components over 45 min to 6 h after intraperitoneal injection, although at 20 min the specific activity was similar to that of nucleoplasmic 5SRNA. Thus, cytosolic 5SRNA of rat liver is characterized by a high rate of turnover, which was shown to be comparable to that of heterogeneous nuclear RNA. The specific activity of 5SRNA, 45 min to 6 h after intraperitoneal injection, was as follows; cytosolic > nucleoplasmic > nucleolar > ribosomal 5SRNA. The specific activity of nucleoplasmic RNA that migrated slightly slower than nucleoplasmic 5SRNA on PAGE was much higher than that of cytosolic 5SRNA or nucleoplasmic 5SRNA, and so may be the precursor of nucleoplasmic 5SRNA. Together, these results indicate that cytosolic 5SRNA is transferred from the nuclei to the cytosol immediately after maturation of the precursor of nucleoplasmic 5SRNA without entering the nucleoplasmic pool of 5SRNA.

Animals↗
PubMed1993

Phosphatidic acid-induced superoxide generation in electropermeabilized human neutrophils.

The ability of phosphatidic acid to induce O2- generation was examined in intact and electropermeabilized neutrophils. In intact cells, after a long lag (approximately 11 min), 1,2-didecanoylphosphatidic acid (PA10, 10 microM) elicited O2- generation (30-40 nmol/min/10(7) cells at maximum) which lasted for 8-9 min. Electropermeabilization facilitated the response by shortening the lag (within 30 s) and enhancing the maximal rate (120-130 O2- nmol/min/10(7) cells). The induction by PA10 was concentration-dependent and the half-maximal concentrations for intact and permeabilized cells were 11 and 3 microM, respectively. In permeabilized cells, the rate of O2- release by PA10, which was similar to that by fMet-Leu-Phe or phorbol myristate acetate, was not enhanced by addition of dioctanoylglycerol. Also, the response was unaffected by propranolol, an inhibitor of phosphatidate-phosphohydrolase that converts phosphatidic acid to diacylglycerol. Phosphatidic acids with longer acyl chains (C12-C14) also activated the permeabilized cells, although the degree of activation decreased as the chain length was increased. These results indicate the ability of phosphatidic acid to induce respiratory burst independently of diacylglycerol and support the idea that phosphatidic acid can be an activator of NADPH oxidase in human neutrophils.

Cell Membrane Permeability↗
PubMed1993

Patellar metastases. A report of two cases.

Primary bone tumours and metastases of the patella are rare. We report two cases of metastases, one from a carcinoma of the salivary gland which was bilateral and the other from extramammary Paget's disease with invasive carcinoma.

Adult↗
PubMed1993

Chemotherapy for minimally differentiated acute myeloid leukemia (AML-M0). A report on five cases and review of the literature.

With the objective of establishing the optimal therapy for minimally differentiated acute myeloid leukemia (AML-M0), we examined the therapeutic results of five AML-M0 cases and reviewed the literature. In a series of 63 patients with newly diagnosed acute leukemia who were admitted to the Main Hospital of Nippon Medical School, five patients fit the criteria for AML-M0: negative myeloperoxidase (MPO) and Sudan black B reaction by light microscopy, negative for B- and T-lineage markers, and positive for myeloid markers. They were treated by means of AdVP [adriamycin, vincristine, and prednisolone (PSL)] therapy and/or BHAC-DMP [behenoylcytosine arabinoside (BHAC), daunorubicin (DNR), 6-mercaptopurine (6-MP), and PSL] therapy. The AdVP therapy was unsuccessful in the two patients who received it, while a complete remission (CR) was achieved with the BHAC-DMP therapy in three of four patients. Although one patient treated with BHAC-DMP did not achieve CR, his blasts were apparently sensitive to the therapy. In assessable cases in the literature where leukemic blasts were MPO-negative, myeloid marker-positive and B- and T-lineage marker-negative, CR was achieved in 54.5% and 44.4% with anti-acute myeloid leukemia therapy and anti-acute lymphocytic leukemia therapy, respectively. Five cases in the literature were treated with a chemotherapeutic regimen containing BHAC [or cytosine arabinoside (Ara-C)], DNR, and 6-MP, and all achieved CR. The regimen containing BHAC (or Ara-C), DNR, and 6-MP may be useful as induction chemotherapy for AML-M0.

Adult↗
PubMed1993

Effects of interleukin 2 on myelodysplastic syndromes.

To evaluate the clinical usefulness of interleukin 2 (IL-2) on myelodysplastic syndromes (MDS), the serum IL-2 level, the effect of IL-2 on the proliferation of blasts, and the cell-mediated cytotoxic effect of IL-2 on blasts were examined in MDS patients. Of 18 patients, 2 patients had an increased serum IL-2 level. Although the proliferation of blasts in most cases, including the two patients having a high serum IL-2 level, was not stimulated by IL-2, the blasts of one case apparently proliferated in response to IL-2. It was also clearly shown that IL-2-stimulated normal peripheral blood mononuclear cells (PBMNC) showed cytotoxicity against MDS blasts, whereas the PBMNC of the advanced stages of MDS were usually defective in regard to this IL-2-dependent cytotoxicity. The therapeutic usefulness of IL-2 or lymphokine-activated killer cells for MDS was not established by the present study.

Cell Division↗
PubMed1993

Extracorporeal life support for patients undergoing prolonged external cardiac massage.

From November 1987 to February 1992, extracorporeal life support (ECLS) was used for four patients undergoing prolonged external cardiac massage following cardiac arrest. Their underlying diseases consisted of acute pulmonary embolism, pulmonary arterial thrombosis due to protein C deficiency, acute inferior left ventricular infarction accompanied by right ventricular infarction and thoracic contusion. After the initiation of ECLS, hemodynamic variables and metabolic acidosis improved in all of the cases. The case of pulmonary embolism and the case of acute myocardial infarction were successfully weaned from ECLS without complications. They were later discharged ambulatory from the hospital. The patient with pulmonary arterial thrombosis, who was comatose, became alert after the initiation of ECLS. However the patient finally died due to diffuse and massive pulmonary arterial thrombosis, which was probably related to protein C deficiency. The patient with thoracic contusion was also comatose before ECLS. He did not recover from the coma and died soon after the disconnection of ECLS. The latter two cases were suspected to have had irreversible organ failures not responsive to mechanical support of both circulation and respiration. We conclude that ECLS is a very useful method for patients requiring prolonged cardiac massage following cardiac arrest.

Adult↗
PubMed1993

Longitudinal study on forces transmitted from denture base to retainers of lower distal-extension removable partial dentures with conus crown telescopic system.

The purpose of this study was to perform longitudinal measurement of forces transmitted from the denture base to retainers of lower distal-extension removable partial dentures with a conus crown telescopic system. The experimental denture was embedded with a force-detecting unit which could detect a change in lateral and vertical forces transmitted from denture base to retainers at the same time. Forces were measured during chewing of food on several separate occasions from the insertion of new dentures to about 3 months after. Max.ver (maximal mean value of vertical force) and Max.lat (maximal mean value of lateral force) were calculated from the peak level of all strokes of chewing of food at the minimum of the interocclusal distance. The results are summarized as follows: (i) There were no significant changes of Max.ver and Max.lat; (ii) There were no significant differences of Max.ver between subjects the value of which was about 20 N; (iii) There were significant differences of Max.lat between subjects the value of which was less than 15 N.

Bite Force↗
PubMed1993

Longitudinal study on torque around the sagittal axis in lower distal-extension removable partial dentures.

The purpose of this study was to examine the longitudinal changes of torque around the sagittal axis in lower distal-extension removable partial dentures. The torque transmitted from the denture base to retainers was measured on several separate occasions from the insertion of new dentures to about 2 months after it. The maximal mean value of torque (Max.MT) was calculated from the magnitude of all chewing strokes of the minimum of the interocclusal distance. The integration values of torque (I) and time (T) from initiation of chewing to swallowing were obtained and then the average value of torque (Ave.T) was calculated (Ave.T = I/T). Subjects could be divided into two groups. Max.MT and Ave.T were almost constant in one group while they were remarkably decreased in another. After 1 month of insertion of new dentures the value of both groups was within the range of less than 3 x 10(-3) kgm (1 kgm = 9.8 Nm) of Max.MT and less than 1 x 10(-3) kgm ss-1 of Ave.T.

Adult↗
PubMed1993

Longitudinal study on torque transmitted from denture base to an abutment tooth of lower distal-extension removable partial dentures with conus crown telescopic system.

The purpose of this study was to make a longitudinal analysis of torque transmitted to a direct abutment tooth of a lower distal-extension removable partial dentures constructed with the conus crown telescopic system. Torque around the vertical and lateral axes of the tooth were measured during chewing of food at the time of insertion of the new dentures to about three months after. The maximal mean value of torque (Max.MT) was calculated from the peak level of all chewing strokes at the minimum of the interocclusal distance. The integration values of torque (I) and time (T) from initiation of chewing to swallowing were obtained, then the average value of torque (Ave.T) was calculated (Ave.T = I/T). The results are summarized as follows: (a) There were no remarkable changes of Max.MT around the both axes; (b) Max.MT around the lateral axis was 7-47 x 10(-3) kgm (mean: 25 x 10(-3) kgm) (1 kgm = 9.8 Nm) in the downward direction and Ave.T around the lateral axis was 6-14 x 10(-3) kgm ss-1 (mean: 10 x 10(-3) kgm ss-1) in the downward direction; (c) There were marked differences of Max.MT and Ave.T around the vertical axis between subjects. Max.MT around the vertical axis was less than 24 x 10(-3) kgm and Ave.T around the vertical axis was less than 6 x 10(-3) kgm ss-1.

Aged↗
PubMed1993

Longitudinal study on occlusal force distribution in lower distal-extension removable partial dentures with conus crown telescopic system.

The purpose of this study was to examine longitudinal changes of the occlusal force distribution in lower distal-extension removable partial dentures with the conus crown telescopic system. Occlusal force applied to the denture and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 3 months after. The occlusal force distribution ratio to the retainers was calculated when a load of 20 N was applied to the denture. The results are summarized as follows: (i) The more posterior the loading point of occlusal force, the smaller was the ratio. When the occlusal force was applied to the most anterior artificial tooth, the ratio was 65-100% of the occlusal force. (ii) As the denture wearing time proceeded, the ratio was decreased. The smaller the ratio, the greater was the rate of its decrease.

Aged↗
PubMed1993

Mycobacterium avium-M. intracellulare binds to the integrin receptor alpha v beta 3 on human monocytes and monocyte-derived macrophages.

Mycobacterium avium-M. intracellulare is an intracellular pathogen responsible for the highest incidence of disseminated bacterial infection in patients with AIDS. Treatment of the infection is difficult and has been of limited efficacy. Attachment of the organism to macrophages is a critical early step in the establishment of the disease. In the present study, we isolated and identified a receptor that mediates attachment of M. avium-M. intracellulare to human peripheral blood monocytes and monocyte-derived macrophages. On Western blotting, (immunoblotting), the receptor was found to cross-react with antibodies against a human vitronectin receptor (alpha v beta 3). The receptor could be purified from monocyte extracts by using monoclonal antibodies (MAbs) against the alpha v subunit of vitronectin receptor coupled to CNBr-Sepharose 4B, as well as with the adhesive tripeptide sequence arginine-glycine-aspartic acid (RGD) coupled to CNBr-Sepharose 4B. Surface-bound MAbs directed against alpha v beta 3 were found to inhibit the attachment of M. avium-M. intracellulare to monocyte-derived macrophages in an in vitro inhibition assay, while MAbs directed against CD14, CD18, alpha 2 beta 1 and platelet glycoprotein gpIIb/IIIa receptors did not inhibit this attachment. These observations suggest that alpha v beta 3 on the surface of human monocytes and monocyte-derived macrophages may function as a receptor for M. avium-M. intracellulare. Identification of a receptor for M. avium-M. intracellulare on macrophages may offer new approaches to the prevention and control of M. avium-M. intracellulare infection at the cellular level.

Amino Acid Sequence↗