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Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 541 records · Page 30Linked to original sources
PubMed1993

Hepatocellular carcinoma: the diagnostic difficulties of ultrasonography and analysis of risk factors in MHTS.

Thirty-nine cases of hepatocellular carcinoma (HCC) out of 55,135 examinees were examined. The diagnostic problems of ultrasonography (US) in detecting HCC and the risk value of 10 factors in HCC were discussed. We also propose the surveillance programs for HCC in Multiphasic Health Testing and Services (MHTS). US will be performed at 3-, or 6 monthly intervals in conjunction with AFP monitoring for the examinees over 50 males and over seventy females with liver dysfunction (GOT > 38 IU/ml) is recommended.

Adult↗
PubMed1993

Clinical evaluation of new cancer-associated antigen CA125 II in epithelial ovarian cancers: comparison with CA125.

With use of monoclonal antibodies (moABs) M 11 and OC125, a sensitive sandwich immunoradiometric assay (IRMA) for CA125 II was developed. CA125 antigen was adsorbed by moAB OC125 and M 11, but horseradish peroxidase-labelled OC125 did not compete with M 11, indicating that although these two moABs recognized CA125 antigen, they reacted with separate antigenic determinants. We also demonstrate that the dual capture technique with OC125 and M 11 antibodies has a larger dynamic range than OC125 alone. This could potentially increase the sensitivity in terms of low CA125 levels. Forty-six patients with ovarian cancer before therapy and a further 20 cases during follow-up were evaluated for the presence of two serum tumor markers: CA125 II and CA125. The overall positive rate for CA125 II was 97.8%, compared with 91.3% with CA125. Serum CA125 II levels were closely correlated with serum CA125 levels (r = 0.918). The mean CA125 II levels before treatment, at response, and at recurrence were 194.3, 19.6, and 103.5 U/mL, respectively. Normalization of serum CA125 II levels at response does not imply absence of microscopic residual disease. CA125 II changes during follow-up suggest recurrence and can be used to monitor individual patients.

Adult↗
PubMed1993

Reduction of the leukemogenic potential of malignant murine leukemic cells by in vivo treatment with recombinant human granulocyte colony-stimulating factor.

We have investigated the effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration on the leukemogenic potential of L-103 murine leukemic cells. Leukemogenic potential was assessed by comparing the regression lines drawn between the number of inoculated leukemic spleen cells and the mean survival time (MST) of the syngeneic recipients. rhG-CSF injected 2.5 micrograms daily for 14 days reduced the leukemogenic potential of spleen cells of the leukemic mice to 1/200 of the control. This phenomenon was not observed with the leukemic spleen cells treated with r-murine granulocyte-macrophage (rmGM)-CSF in vivo. Cytochemical study indicated that morphologically identifiable blast cells were fewer in the rhG-CSF-treated leukemic spleen. Furthermore, leukemic cells in the rhG-CSF-treated spleen were less proliferative than the control in spite of having more clonogenic cells in the leukemic cell preparation. Cytogenetical analysis showed that chromosome abnormalities found in the original leukemic cells were not altered by rhG-CSF administrations. It also showed that the frequency of the abnormal karyotype was reduced in rhG-CSF-treated leukemic spleen (4/17) as compared with the control (8/8), indicating that the mitotic fraction was smaller in the rhG-CSF-treated leukemic cells. These findings indicate that in addition to the reduced number of leukemic cells in the spleen cell preparation, a reduction of the proliferative capacity of the original leukemic cells is involved in the reduction of leukemogenic potential of leukemic cells treated with rhG-CSF in vivo.

Animals↗
PubMed1993

Temporal and spatial localization of steroidogenic enzymes in premenopausal human ovaries: in situ hybridization and immunohistochemical study.

In situ hybridization and immunohistochemical localization of cytochrome P450 cholesterol side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), cytochrome P450 17 alpha-hydroxylase (P450c17) and cytochrome P450 aromatase (P450arom) was performed in 50 morphologically normal human premenopausal ovaries, and correlated these findings with their endometrial phase. In general, mRNA expression of these enzymes examined by in situ hybridization were in good agreement with immunolocalization examined by immunohistochemistry. Expression of P450scc, 3 beta HSD and P450c17 was observed in large-sized preantral follicles, consisting of more than five layers of granulosa cells, preovulatory follicles, corpora lutea, and some degenerating corpora lutea and atretic follicles in all endometrial phases. Several follicles and/or corpora lutea positive for these enzymes were observed in the same ovary. Expression of P450arom was generally observed in only one follicle (antral or preovulatory follicle) or corpus luteum per case in mid proliferative to premenstrual phase, and was not observed in menstrual to early proliferative phase. These findings indicated that (1) expression of steroidogenic enzymes was associated with the continual human ovarian process including follicular development and atresia, and (2) especially, P450arom expression may occur only in a selected antral follicle and may have an important role in dominant follicular development.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

Protective cross-reactive epitope on the nonstructural protein NS1 of influenza A virus.

We reported previously that adoptive immunization with an influenza A virus NS1-specific H-2Ld-restricted, cross-reactive, CTL clone A-11 established by stimulation with A/PR/8/34 virus (H1N1) reduced lung virus titers in mice challenged with virus in vivo (Virology 178:174-179, 1990). Using a set of recombinant vaccinia virus constructs containing truncated portions of the NS gene we have localized this cross-protective CTL epitope to the N-terminal region of the NS1 protein. This region of NS1 is active in inducing CD8+ CTL in vivo because virus-stimulated BALB/c immune spleen cells in bulk cultures also recognized the N-terminal region of the NS1 protein.

Animals↗
PubMed1993

Distribution of tenascin in normal cycling human ovary.

Tenascin is an extracellular matrix glycoprotein, which has been reported to be involved in parenchymal-mesenchymal interactions during morphogenesis, wound healing, and carcinogenesis. Tenascin immunolocalization was performed in 51 specimens of morphologically normal human ovaries by using a specific monoclonal antibody against purified human fibroblast tenascin. In preovulatory follicles, no significant immunoreactivity was detected. In functioning corpora lutea, immunoreactivity was present as a fine border around the periphery. In association with the involution of the corpora lutea, marked diffuse tenascin immunostaining in the intercellular space was observed. These data raise the question of whether tenascin may be involved in luteolysis and may play an important role in the ovarian cycle by regulating the involution of corpora lutea.

Cell Adhesion Molecules, Neuronal↗
PubMed1993

Preparation and optical characteristics of hemoglobin-free isolated perfused rat head in situ.

Using a new cannulation method, which completely prevented interruption of circulation to brain tissue during surgical operations, we could prepare a functionally intact hemoglobin-free isolated perfused rat head in situ. The frequency distribution (8-25 Hz) and amplitude of a spontaneous electroencephalogram, EEG (50 microV), were kept within the normal ranges for up to 4 h after the perfusion was started. Our preparation gave characteristic flash-evoked EEG responses through the eyes. The administration of bicuculline elicited an epileptic seizure similar to that in normal rats. Near-infrared difference spectra of the rat head obtained on an aerobic to anaerobic transition were similar to those of cytochrome oxidase in isolated mitochondria as well as in the purified state. Under the aerobic perfusion conditions, both heme a+a3 and copper in cytochrome oxidase were in the fully oxidized states, showing that normoxia was maintained in the brain tissue. The redox behaviors of these two chromophores in the brain were identical to those observed in isolated mitochondria. The usefulness of brain perfusion for bridging in vitro and in vivo studies is well documented.

Animals↗
PubMed1993

Possible contribution of potassium channels to the endothelin-induced dilatation of rat coronary vascular beds.

The mechanism for the endothelin (ET)-induced vasodilatation of the endothelium-intact rat coronary vascular bed was investigated. Continuous infusion (0.1-1 nM) or bolus injection (1-100 pmol) of ET-1 or ET-3 elicited a dose-related transient decrease, followed by a slight sustained increase, in the coronary perfusion pressure (CPP). The decrease in CPP induced by an injection (10 pmol) of ET-1 or ET-3 was not modified by indomethacin (5 microM). However, oxyhemoglobin (5 mM) shortened the duration of the ET-induced decrease in CPP, although it did not affect the magnitude. The ET-induced decrease in CPP was abolished by raising K+ in the perfusing solution from 5.9 to 16.9 mM. These findings suggest that the ET-induced dilatation of the rat coronary vascular beds may not be mediated by cyclooxygenase products. The ET-induced vasorelaxation may be mediated, at least in part, by endothelium-derived relaxing factor and may be related to opening of K+ channels.

Animals↗
PubMed1993

Comparison of virulence between Seoul virus strain SR-11 and Hantaan virus strain 76-118 of hantaviruses in newborn mice.

Virulence of hantavirus strain of SR-11 Seoul virus and Hantaan 76-118 (HTN) of Hantaan virus were compared. Infections of both strains were lethal in newborn mice. However, inoculum required to cause lethal infection was about 4,000 times higher for strain HTN (1.65 x 10(3) PFU/mouse/LD50) than for strain SR-11 (0.36 PFU). Thus, both strains were considered pathogenic to newborn mice but they possessed different levels of virulence. The assay system used for these strains in newborn mice proved to be useful in the study of hantavirus virulence. Growth curves of the two strains in CV-7 cell cultures were compared. Strain SR-11 was shown to have higher activity of virus replication and virus release into the culture fluids than strain HTN. The possibility of a relationship between replication activity and high levels of virulence in mice was suggested.

Animals↗
PubMed1993

Development of an artificial placenta: survival of isolated goat fetuses for three weeks with umbilical arteriovenous extracorporeal membrane oxygenation.

The purpose of our study was to examine the feasibility of long-term extrauterine incubation of an isolated premature fetus in artificial amniotic fluid with arteriovenous extracorporeal circulation. Two premature goat fetuses (age 120 and 128 days) were incubated in an isothermal artificial amniotic fluid incubator with arteriovenous extracorporeal membrane oxygenation via the umbilical vessels. We administered pancuronium bromide to suppress fetal movement and swallowing because movement and swallowing have been implicated in fetal deterioration during extrauterine fetal incubation. The fetuses maintained stable circulatory and respiratory parameters. The total incubation time was 494 and 543 h. The animals were then removed from the incubator and stimulated to initiate lung respiration. With ventilator support, both animals maintained stable blood-gas exchange and survived for more than 1 week. These results clearly indicate that umbilical arteriovenous extracorporeal membrane can effectively support extended extrauterine incubation of an isolated premature fetus.

Amniotic Fluid↗
PubMed1993

Cytokine induction by extracellular products of oral viridans group streptococci.

During an etiological study of Kawasaki disease (mucocutaneous lymph node syndrome [MCLS]), we found that dominant viridans streptococcal strains on tooth surfaces and in the throat of both MCLS patients and non-MCLS control children formed erythrogenic and biologically active, extracellular products. In this study, we demonstrated that erythrogenic culture supernatant concentrates of representative strains (two Streptococcus mitis and two Streptococcus oralis), when injected intravenously, induced serum tumor necrosis factor alpha, interleukin-6 (IL-6), and gamma interferon in muramyldipeptide- or Propionibacterium acnes-primed C3H/HeN mice. The concentrates also induced tumor necrosis factor alpha, IL-6, and thymocyte-activating factor (essentially IL-1) in murine peritoneal macrophage, human monocyte, and human whole-blood cultures. An erythrogenic, heat-labile extracellular protein fraction (F-1) that was concentrated from the culture supernatants of a representative S. mitis strain exhibited the above-mentioned cytokine-inducing activity. This partially purified F-1 fraction also induced thymocyte-activating factor and IL-6 in human umbilical vascular endothelial cell and gingival fibroblast cultures.

Animals↗
PubMed1993

Oxygen dependence of redox state of copper in cytochrome oxidase in vitro.

To obtain quantitative information about tissue oxygenation from near-infrared signals, the oxygen dependencies of the redox states of both heme a+a3 and copper in cytochrome oxidase of isolated mitochondria were determined at low oxygen concentrations (10(-6)-10(-9) M) using leghemoglobin as an oxygen indicator. The maximum absorbance changes caused by the aerobic-anaerobic transition measured at 830-760 nm of copper in state 3, state 4, and the uncoupled state were 10, 17, and 5% of those at 605-620 nm of heme a+a3, respectively. Thus the relative absorbance ratio of copper to heme a+a3 could be used as a sensitive indicator for the mitochondrial energy state. The oxygen concentrations required for the half-maximal reduction of heme a+a3 varied with the energy state and the respiratory rate and were 7.8 x 10(-8) and 1.6 x 10(-7) M in state 4 and state 3, respectively. In contrast, that of copper was 7.5 x 10(-8) M and was independent of both the energy state and the respiratory rate. The relationship between the percent oxidation of heme a+a3 and copper in the aerobic-anaerobic transition did not show a straight-line relationship. This was referred to as the difference in oxygen affinity between these two chromophores. The deviation from the straight line was larger in state 3 than in state 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗
PubMed1993

Dynamic multichannel near-infrared optical imaging of human brain activity.

The present paper demonstrates functional brain mapping with an optical imaging technique by using tissue-transparent near-infrared light. With a maximal five-channel optical monitoring system, we succeeded in detecting region-specific changes in both the hemoglobin oxygenation state and blood volume during various mental tasks, in addition to visual and auditory stimulation. The time course of increases in blood supply varied with each brain region and depended on the type of internal operations occurring during the mental tasks. Changes in the hemoglobin oxygenation state were also different from region to region. This showed that there were regional variations of the oxygen delivery-oxygen utilization relationship during activation of brain activity. The usefulness of multichannel near-infrared functional imaging was well documented.

Acoustic Stimulation↗
PubMed1993

An enzymological profile of the production of lactic acid in caries-associated plaque and in plaque formed on sound surfaces of deciduous teeth.

Specific activities of lactate dehydrogenase (LDH) and its fructose 1,6-bisphosphate (FBP) dependency in the small amount of plaque formed on deciduous teeth were determined and compared between those from carious lesions and from sound surfaces. Although the caries-associated plaque showed a higher production of lactic acid than the plaque formed on sound surfaces, it occurred only when sufficient FBP was present. The proportion of activity of FBP-dependent LDH relative to that of total LDH varied much more in the caries-associated plaque than in the plaque formed on sound surfaces. Hence, the varying activity of FBP-dependent LDH might be a distinguishing feature of caries-associated plaque compared with plaque formed on sound surfaces.

Child↗
PubMed1993

Relationship between tissue polyamine levels and malignancy in primary brain tumors.

We studied the relationship between tissue polyamine levels and malignancy in 146 primary brain tumors. Astrocytoma showed a consistent rise in levels of N1-acetylspermidine (N1-AcSpd) in tissue with increased grade of malignancy. Furthermore, in astrocytoma, the patients whose tumors contained high levels of N1-AcSpd (> or = 15 nmol/g) in tissue showed a far worse prognosis, a significantly lower recurrence-free survival rate, and a shorter survival rate than did the patients whose tumors contained lower levels of N1-AcSpd (< 15 nmol/g). High-grade astrocytoma contained N1-AcSpd at the level of 15 nmol/g or higher, and most of the benign brain tumors, including low-grade astrocytoma, meningioma, pituitary adenoma, and normal brain tissues contained much lower levels of N1-AcSpd. However, medulloblastoma, hemangiopericytoma, and neurinoma showed an inverse correlation between N1-AcSpd levels in tissue and biological malignancy. These results suggest that levels of N1-AcSpd in tissue can be a promising biochemical marker of malignancy in astrocytoma. In the other primary brain tumors, however, the relationship between levels of N1-AcSpd in tissue and biological malignancy should be examined in each histopathological type.

Adolescent↗
PubMed1993

Synthesis and evaluation of (piperidinomethylene)bis(phosphonic acid) derivatives as anti-osteoporosis agents.

Some (piperidinomethylene)bis(phosphonic acid) derivatives were prepared and their activity to inhibit a rise in serum calcium induced by parathyroid hormone in thyroparathyroidectomised rats was evaluated. Several (4-alkylidene-, 4,4-dialkyl-, or 4-alkyl-4-halopiperidinomethylene)bis(phosphonic acid) derivatives showed considerable inhibitory activity. But compounds having aromatic and polar substituents such as azido, hydroxy, amino and amido on the piperidine ring were generally inactive. In this study, two 4-alkylidene compounds (8a and 8b) and a 4,4-cyclic dialkyl compound (61) showed potent activity when administered either intravenously or perorally.

Animals↗
PubMed1993

Non-invasive monitoring of the redox state of cytochrome oxidase in living tissue using near-infrared laser lights.

A triple wavelength spectrophotometric method was developed to monitor changes in the concentrations of oxygenated and deoxygenated hemoglobin, and in the redox state of cytochrome oxidase in living tissue. Three wavelengths of an NIR (near-infrared) laser beam were used to monitor hemoglobin (780, 805 and 830 nm) and cytochrome (cyt.) oxidase (780, 790 and 830 nm). Algorithms for calculating changes in the concentrations of oxidized cyt. oxidase (aa3), and oxygenated and deoxygenated hemoglobin were developed using NIR spectral analysis of these chromatophores. To assess the ability of these algorithms to measure independent changes in the concentration of oxy-, deoxyhemoglobin and oxidized cyt. oxidase in tissue, experiments involving a fluorocarbon (FC-43) exchange transfusion at very low hematocrits were conducted in anesthetized rats. The observed data indicate that FC-43 circulation at FiO2 1.0 can supply sufficient oxygen to the rat brain to maintain the oxidation state of mitochondrial oxidase (cyt.aa3) near pre-exchange levels. The relationships between changes in oxidized cyt. oxidase and oxyhemoglobin content in response to variations in FiO2 of inspired gas were then examined in the rat brain. These results also confirmed the ability of the triple wavelength algorithms to distinguish changes in the oxidized copper band of cyt.aa3 from those in absorption by oxy- and deoxyhemoglobin. NIR monitoring of skeletal muscle to determine the redox state of cyt. oxidase was performed in a few human cases and the results indicated that these observations can increase our understanding of the process of oxygen transport to tissues.

Algorithms↗