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Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 307 records · Page 17Linked to original sources
PubMed1990

Partial purification and characterization of human megakaryocyte colony-stimulating factor (Meg-CSF).

Megakaryocyte colony-stimulating factor (Meg-CSF) in urinary extracts from patients with aplastic anemia was partially characterized and purified. Using Meg-CSF-enriched fractions, we established that the moiety has the following characteristics: 1) portions of the molecules having Meg-CSF activity have sialic acid, probably with a biantennary structure, and beta-galactose residues as the terminal and penultimate sugars; 2) disulfide residues are an essential chemical group of the molecule and are located on its surface; and 3) Meg-CSF activity is stable in n-propanol, but not in acetonitrile with trifluoroacetic acid. Partial purification of Meg-CSF by a four-step procedure of ethanol precipitation, CM Affi-Gel Blue chromatography, wheat germ agglutinin-sepharose chromatography, and high-resolution hydroxyapatite chromatography, yielded a concentrate with a 430- to 630-fold increase in specific activity. The partially purified Meg-CSF fractions stimulated both human and murine megakaryocytopoiesis in vitro (CFU-meg). When analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreduced conditions, Meg-CSF activity was recovered in the 29-34 kDa molecular weight fractions. We have also shown that Meg-CSF, purified from the urine of aplastic anemia patients, stimulated murine megakaryocytopoiesis and platelet production in vivo. Final purification of human urinary Meg-CSF is currently in progress.

Anemia, Aplastic↗
PubMed1990

Enhancing effect of S-(1,2-dicarboxyethyl)glutathione on epidermal growth factor-stimulated DNA synthesis in primary cultures of adult rat hepatocytes.

A tripeptide S-(1,2-dicarboxyethyl)glutathione (DCE-GS) has been reported to be present in the lens, liver, and heart. Effects of DCE-GS and its derivatives and analogues on hepatocyte deoxyribonucleic acid (DNA) synthesis were examined using primary cultures of adult-rat hepatocytes. DCE-GS alone had no effect on DNA synthesis of hepatocytes. However, when DCE-GS was added with epidermal growth factor (EGF), the tripeptide effectively enhanced EGF-stimulated DNA synthesis of hepatocytes under the culture conditions of low cell density, but not high cell density. On the other hand, some esters and amides of DCE-GS and DCE-GS analogues showed a suppressive effect on DNA synthesis of hepatocytes in the absence of EGF. The derivatives and analogues together with EGF had no effect or rather a suppressive effect on stimulation of hepatocyte DNA synthesis by EGF. Therefore, the two carboxy groups in the substituent probably play an important role in the stimulative activity of DCE-GS. In addition, it seems likely that one of in vivo physiological roles of DCE-GS is related to liver regeneration.

Animals↗
PubMed1990

Oblique tibial osteotomy for rotational and varus deformities in children.

A technique of oblique tibial osteotomy is described which is effective in correcting varus and medial rotational deformities in young children. The oblique cut in one plane corrects both elements of the deformity at the same time. We have used the method on both legs in four children and satisfactory results were obtained.

Child, Preschool↗
PubMed1990

Measurement of blood flow in rabbit bone transplants.

The rate of blood flow in free bone grafts in rabbits was monitored for 8 weeks after transplantation using the hydrogen washout technique. Blood flow was present at 2 weeks in both autografts and allografts, although the rate was significantly lower in the allograft compared to the autograft. Autografts showed a rapid increase from 2 to 3 weeks and a maximum flow 4 weeks after transplantation, whereas in allografts the rate of increase was slower. This study has demonstrated that the hydrogen washout technique is a useful method of monitoring blood flow and can be applied to clinical investigations.

Animals↗
PubMed1990

Anti-thoracic duct lymphocyte globulin stimulates human megakaryocytopoiesis in vitro.

Anti-thoracic duct lymphocyte globulin (ALG) therapy is effective in patients with aplastic anemia. We examined the effect of ALG on human megakaryocyte progenitor cells (colony-forming unit-megakaryocyte, CFU-Meg) in vitro. Normal human bone marrow mononuclear cells (MNC) were cultured in plasma clots with varying concentrations of ALG or non-immunized horse IgG. After 12 days of culture, significant megakaryocyte colony formation was observed in cultures containing ALG but not in cultures containing non-immunized horse IgG. The peak stimulatory effect seemed to occur with 10-25 micrograms/ml of ALG. When marrow MNC, depleted of adherent and T cells, were cultured in plasma clots with ALG, its stimulatory effect on megakaryocytopoiesis decreased markedly. Finally, it was demonstrated that ALG stimulated marrow MNC to produce a factor stimulatory for CFU-Meg. The in vitro megakaryocytopoietic stimulatory effect of ALG may be related to its clinical efficacy in some patients with aplastic anemia.

Antilymphocyte Serum↗
PubMed1990

Humoral immune responses in experimental gingivitis in rats.

Serum IgG, IgM, and IgA antibody levels to extracts of rat dental plaque and five oral bacteria (Haemophilus actinomycetemcomitans Y-4, Bacteroides gingivalis 381, Bact. intermedius ATCC 25261, Capnocytophaga sp. M-12, Eikenella corrodens ODU) were determined by ELISA. In addition, the presence of rat dental plaque and oral bacterial components in the inflamed gingival tissue was studied using immunofluorescence techniques. Serum and gingival tissue samples were obtained from ODU plaque-susceptible and plaque-resistant rats. In several susceptible rats, IgG, IgM, and IgA antibodies against dental plaque and oral bacteria were detected. There was a correlation between the levels of IgG antibody to dental plaque and pocket probing depth, but not between pocket probing depth and the levels of IgM and IgA. Furthermore, components of rat dental plaque and oral bacteria were detected in the inflamed gingival tissue.

Animals↗
PubMed1990

Leucocyte function in rats with naturally occurring gingivitis.

The severity of gingivitis in relation to abnormal macrophage chemotaxis and superoxide (O2-) production was investigated in rats with naturally occurring gingivitis (plaque-susceptible rats). Macrophage chemotaxis was measured by the membrane filter method; zymosan-activated serum was used as a chemo-attractant. O2- production was measured by the reduction of cytochrome c method. Opsonized zymosan, phorbol myristate acetate and calcium ionophore A23187 were used as stimulants. The macrophage chemotaxis and O2- production in the plaque-susceptible rats with deep pockets were significantly lower than those in the susceptible rats with shallow pockets or the normal group. In addition, there was a negative correlation between the severity of gingivitis in plaque-susceptible rats and macrophage chemotaxis or O2- production. These findings suggest that impairement of the host defence mechanisms due to the reduction in macrophage chemotaxis and O2- production is related to the progression of periodontal disease in plaque-susceptible rats.

Animals↗
PubMed1990

Clinicopathological study of kidneys from patients on chronic dialysis.

Kidneys removed from 58 pediatric patients at renal transplantation (except 3 cases), who had developed chronic renal failure and were maintained on dialysis, were investigated histopathologically, and the clinical profiles were taken into account. The patients ranged in age from 2 to 24 years, with an average of 11.2 years. The duration of dialysis ranged from 0.5 to 63 months, with an average of 12.6 months. The kidneys, which were conventionally prepared for histological observation, were subjectively divided into three groups depending on the degree of remaining nephrons. Patients with completely atrophic type (type 1), incompletely atrophic type (type 2), and mixed type of atrophy and hypertrophy (type 3) had a duration of dialysis of 20.0, 12.3, 6.3 months, respectively (Type 1 greater than Type 3, P less than 0.01). A correlation between histology and function was demonstrated, since urinary output was more than 200 ml/day in most of the type 3 patients, and less than 20 ml/day in all of the patients with type 1. The findings suggest that the functioning nephrons that remained at the beginning of dialysis generally become atrophic within one year after the initiation of dialysis. The ratio of kidney weight to body weight showed a significant negative correlation with both the duration of dialysis and that of illness. The histopathological changes seen in kidneys of patients on dialysis were reviewed. The findings suggested that certain changes, unusual epithelial proliferations an oxalate deposition, are associated with persisting renal function rather than the duration of dialysis.

Adolescent↗
PubMed1990

Pathogenesis of Vibrio parahaemolyticus: intraperitoneal and orogastric challenge experiments in mice.

It has been noted that V. parahaemolyticus isolated from patients with food poisoning are almost always thermostable direct hemolysin (TDH)-positive, whereas, isolates from foods or environmental sources are usually TDH-negative. The virulence of V. parahaemolyticus in mice was examined by using intraperitoneal and orogastric challenge models, where the strains used were those isolated from patients and foods with food poisoning and included TDH-positive and -negative. The LD50 in mice was estimated to be approximately 10(7) in the former and 10(8) in the latter challenge model. In the mice killed by challenge, either intraperitoneal or orogastric, the following pathological changes were almost always observed: swelling, redness and fluid accumulation in the small intestine, particularly the upper part of it. Histologically, congestion, edema, and vacuolation were observed in mucosal and submucosal tissues; furthermore, ulceration at tips of some villi was noticed. The lethality and pathological finding in mice due to V. parahaemolyticus were demonstrated similarly in both challenge models and irrespective of the TDH phenotype of the strain used. It will be suggested that the findings in challenged mice may be attributed to enteropathogenic factor(s) other than TDH of V. parahaemolyticus.

Animals↗
PubMed1990

The influence of spacers on forces exerted on the abutment teeth of complete mandibular overdentures.

The avoidance of lateral forces on overdenture retainers is essential to prevent pathological change in the supporting tissues of the root abutment. In this study, the influence of spacer thickness on the vertical and lateral forces exerted on overdenture abutments was examined clinically. Two subjects with an edentulous maxilla, two canines and a left first premolar remaining in the mandible were selected for the experiment. The anchor type attachment was embedded in the left canine portion of the denture base. The transducer used for the previous study (Ogata et al., 1990), was embedded in this left canine portion. The transducer could detect the magnitude and direction of lateral forces exerted on an abutment tooth parallel to the Camper's plane. The other transducer was embedded in the left first mandibular premolar area, and could detect vertical forces exerted on the abutment tooth perpendicular to the Camper's plane. Furthermore, the transducer could change the space between a denture base and an abutment tooth to 1.5 mm, 0.6 mm or 0.3 mm. Therefore measurements could be made in the same way as if three experimental dentures had been used with a different thickness spacer. Recordings of forces were taken during food chewing, using each spacer on the day of denture insertion and twice at intervals of 1-2 weeks thereafter. The results demonstrated that as spacer thickness decreased, the magnitude of the lateral forces decreased, while the magnitude of the vertical forces increased. These findings suggest that a large part of the lateral component of forces exerted on an abutment tooth could be converted into a vertical component by using a thinner spacer.

Bite Force↗
PubMed1990

Occlusal force distribution in lower complete overdentures.

A space between the denture base and a root cap can effectively control the distribution ratio of occlusal force to abutment teeth and an alveolar ridge. The purpose of this study on abutments was to analyse the effect of variation in space (0 mm (no space), 0.3 mm and 0.6 mm) on the above ratio. Six subjects, 38-65 years of age, each with an edentulous maxilla and several teeth remaining in the mandible, were selected for this experiment. The lower experimental denture had embedded a transducer which could detect a change in the vertical force applied to the experimental tooth. This transducer was capable of changing the vertical space between a denture base and an experimental tooth. Each subject was asked to increase the occlusal force applied to the denture from zero to the maximum loading rate of 5 kgf s-1. The occlusal force and the force exerted on the experimental tooth were recorded in each space 1 month after insertion of new dentures. The following results were obtained: (i) when the occlusal force was applied to the artificial tooth just above the abutment tooth, the mean ratio in the 0 mm space was 60% of the force applied to the denture, the ratio in the 0.3 mm space was 50%, and the ratio in the 0.6 mm space was 30%; (ii) if the occlusal force was applied to the point 10 mm distant from the point just above the experimental tooth, the magnitude of the ratio was decreased by 60-80%.

Adult↗
PubMed1990

Isolation of multiple cytomegalovirus strains from a patient with adult T cell leukemia.

A 66-year-old male with adult T cell leukemia had an ulcer on the left medial thigh. The biopsy of the skin lesion revealed enlarged endothelial cells with acidophilic intranuclear inclusion bodies, suggesting cytomegalovirus (CMV) infection. At autopsy, CMV was isolated from a nodular skin lesion of the scrotum. The urine constantly tested positive for CMV. Restriction endonuclease cleavage analysis of DNA of the isolates from the skin and urine indicated that this patient was infected with two different strains of CMV.

Aged↗
PubMed1990

[A transducer for the measurement of torque transmitted to abutment teeth of removable partial dentures].

A transducer for the measurement of torque transmitted to abutment teeth of removable partial dentures was newly developed. The transducer was composed of a right cylinder (12.0 mm x 3.5 mmø) made of phosphor bronze as the torsion bar, to the surface of which two strain gauges (KFC-2-D2-11, KYOWA) are adhered symmetrically about the axis of the bar. Torque transmitted to the transducer was detected and evaluated as tensile strain and compressive strain on the torsion bar surface by means of strain gauges. The transducer was small enough to be easily applied to removable partial dentures for the measurement of torque transmitted to crowns of abutment teeth, and showed satisfactory precision (The instrumental error in measurement was within 3%). In the present study, the newly developed transducer was revealed to be useful for the measurement of torque transmitted to crowns of abutment teeth by removable partial dentures.

Dental Abutments↗
PubMed1990

[Diverse hemostatic abnormalities in a patient with biclonal multiple myeloma].

A 58-year-old female was referred to us because of M-proteinemia and anemia. Bone marrow showed normal cellularity with 14.8% of atypical plasma cells. Serum electrophoresis on cellulose acetate membrane revealed a single M-peak (56.9%). Immunoelectrophoresis showed large M-bows against anti-IgA and anti-lambda, together with small M-bows against anti-IgG and anti-kappa of the same electrophoretic mobility. In the urine, lambda type Bence Jones protein was found. The skull X-ray showed multiple punched out lesions. APTT was 61 seconds, fibrinogen 118 mg/dl, factor VIII clotting activity 25% with normal factor VIII related antigen, and factor IX clotting activity 38%. Circulating anticoagulants were not detected. These hemostatic abnormalities were thought ascribable to the interference of clotting activities by paraproteins. On the 33rd hospital day, she suffered from intracerebral hemorrhage, which was possibly due to these hemostatic abnormalities.

Blood Coagulation Disorders↗
PubMed1990

[Treatment of four cases of B-cell lymphoma].

Four cases of B cell lymphoma, seen at the Department of Dermatology, Miyazaki Medical College, for the previous approximately 10 years, were reviewed. Case 1 was characterized by a localized tumours lesion on the head; the histologic picture was of the follicular, medium sized cell type. Complete remission for 8 years has been obtained after electron beam therapy and surgical removal of the tumor. Cases 2 and 3 had a histologic picture of diffuse, large cell type and were assumed to have a bad prognosis with standard chemotherapy. In addition to conventional chemotherapy, they were placed on noncross-resistant alternating combination chemotherapy with medium dosages of MTX, VP-16, VDS, PCZ MXT, PEP and ACR, so as not to develop cross resistance. Case 2 has been in complete remission for 11 months and case 3 for 7 months. Case 4 was a nodal lymphoma with skin lesions. This patient was treated mainly by local radiation therapy, but later died with leukemic changes and renal failure. Cutaneous B cell lymphoma should be treated vigorously and carefully, since it has a poorer prognosis than that of lymphoma of lymph node origin.

Aged↗
PubMed1990

[Studies of CT images of bronchial tuberculosis, in reference to its pathogenesis].

CT images of 18 patients with bronchial tuberculosis were studied and pathogenesis of the disease was analyzed on the basis of CT findings. Characteristic CT findings, observed in 15 cases, were thickening of bronchial wall and/or swelling of adjacent pulmonary arteries in peripheral part of bronchial tuberculosis lesion. In 11 of these 15 cases, observed pulmonary cavity and/or large tuberculosis lesions at the periphery of the above-mentioned CT findings, were considered to develop to the direct extension from parenchymal tuberculosis. Other 4 cases showed the above-mentioned characteristic CT findings, but without parenchymal lesions, the pathogenesis of the disease remained undetermined. In remaining 3 cases, neither characteristic CT findings nor remarkable parenchymal lesion was noticed. One of them was clarified by bronchoscopic examination.

Adult↗
PubMed1990

Three stages of differentiation in mouse megakaryocyte progenitor cells (CFU-Meg).

Mouse megakaryocyte colonies developed in a fibrin clot culture system were morphologically classified into three types: immature homogeneous (IH), heterogeneous (H), and mature homogeneous (MH) colonies. The colony size (number of megakaryocytes per colony), the ploidy distribution of megakaryocytes in colonies, and the ratios of their progenitors (megakaryocyte colony-forming units, CFU-Meg) in the S-phase of the cell cycle were compared among the three types. Also, morphological changes in colonies were examined in time sequence. The mode of the number of megakaryocytes per colony on day 6 of culture was greater than 64, between 17 and 32, and between 4 and 8, in IH, H, and MH colonies, respectively. The mean DNA content of megakaryocytes was 3.1N, 4.2N, and 7.2N on day 6 of incubation, in IH, H, and MH colonies, respectively, these values being significantly different from each other (p less than 0.001). The mean proportion of CFU-Meg synthesizing DNA was 21.9%, 26.0%, and 48.6% for CFU-Meg forming IH, H, and MH colonies, respectively (p less than 0.01; IH- versus MH-CFU-Meg and H- versus MH-CFU-Meg). Successive observation of the colony morphology from days 5 to 11 of culture suggested a transformation of the colony types from IH colony to MH colony through H colony. These observations indicate that the three types of megakaryocyte colonies classified on the basis of their morphological features reflect various stages of differentiation of mouse CFU-Meg.

Animals↗