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Biomedical subjects

M Miwa

Publications and source records attributed to M Miwa.

At least 145 records · Page 8Linked to original sources
PubMed1993

A method to estimate the ratio of absorption coefficients of two wavelengths using phase-modulated near infrared light spectroscopy.

Near infrared spectroscopy is a very useful tool for monitoring the oxygen saturation of living tissue noninvasively. We can calculate the hemoglobin oxygen saturation within tissue, using the ratio of the absorption coefficients (mua) at two different wave lengths of light. Biological tissue has a very high effective scattering factor (mu's), which elongates an optical path length and makes it difficult to compute the mua by the conventional method using continuous light. Phase-modulated spectroscopy (PMS) measures the path length which is a complex function of the mua and mu's. To obtain the ratio for mua, we have to eliminate the effects of the mu's from the obtained value by the PMS method. In this report, we present a theory and an experimental result which show that the inverse of the squared ratio of two phase angle differences at two different separations obtained by two different light wavelengths provides a good estimate of the ratio at these wavelengths.

Algorithms↗
PubMed1993

Characterization of absorption and scattering properties of small-volume biological samples using time-resolved spectroscopy.

With time-resolved spectroscopy, we develop an experimental approach by sample substitution to measure the absorption (mu a) and reduced scattering (mu's) coefficients of small-volume biological samples. To investigate the method, small-volume control samples are substituted into a large-size host medium during increases in the absorber (or scatterer) concentration of the host. By characterizing the deviation of the spectra taken with and without the sample, we determine the matching points where the sample and surrounding medium are optically identical. We show that this method can result in correct values of the mu a and mu's for the sample within 6% error if the matching conditions for both the mu a and mu's are fully realized. The results also indicate that this method can give approximate values of the mu a and mu's in a reasonable range if either the mu a or the mu's matching between the two media is realized. This method has been applied to the studies of absorption properties of a human finger and of scattering properties of yeast.

Absorption↗
PubMed1993

Temperature-dependent antimutagenic activity of acrolein in Escherichia coli.

The effect of temperature on the antimutagenic activity of acrolein was investigated using UV-irradiated E. coli B. When incubated at lower temperatures (30 degrees C or 37 degrees C), acrolein greatly reduced the mutation frequency in WP2 (wild-type strain), but no such effect was observed with WP2s and ZA159 (excision repair-deficient strains). The antimutagenic activity of acrolein increased when cells were incubated at higher temperatures (40 degrees C or 42 degrees C). Particularly in excision repair-deficient strains, the antimutagenic activity was observed only at higher temperatures. In heat shock response-deficient background, however, the antimutagenic activity was observed at 30 degrees C even in the excision repair-deficient strains.

Acrolein↗
PubMed1993

Eisenin (L-pyroGlu-L-Gln-L-Ala), a new biological response modifier.

Eisenin (L-pyroGlu-L-Gln-L-Ala), a tripeptide extracted from a brown marine alga (Eisenia bicyclis Setchell) showed the immunological activity to augment natural cytotoxicity of peripheral blood lymphocytes (PBLs) in humans. This activity could be seen when it was added directly to 51Cr release assay, and also when PBLs alone were incubated with this compound for 0.5-1 h before addition to the 51Cr release assay. The resulting augmented cytotoxicity can be attributed to natural killer cells because treatment of eisenin-stimulated PBLs with anti-Leu 11b monoclonal antibody (mAb) plus complement completely abolished the augmented cytotoxicity, and, moreover, deletion of Leu 19-positive cells with anti-Leu 19 mAb (mouse IgG1) and anti-mouse IgG-coated magnetic beads showed the same effect. Eisenin could not augment natural cytotoxicity of Sephadex G-10 column-eluted cells. Eisenin rendered K-562 target cells resistant to lysis by PBLs stimulated by eisenin. Both amino acids, L-pyroglutamic acid and L-alanine, as well as a mixture of the three component amino acids of eisenin could augment the natural cytotoxicity. Therefore, it is considered that the structure responsible for the augmentation of natural cytotoxicity by eisenin may be that of the amino acids.

Alanine↗
PubMed1993

Cross-talk between Ca2+ influx and phosphoinositide hydrolysis by extracellular adenosine triphosphate in rat PC12 pheochromocytoma cells.

In rat PC12 pheochromocytoma cells, extracellular ATP stimulated 45Ca2+ influx even in the presence of nifedipine, a Ca2+ antagonist that inhibits the voltage-dependent L-type Ca2+ channel, and stimulated the formation of inositol trisphosphate (IP3). The effect of ATP on 45Ca2+ influx was more potent than that on the formation of IP3 at a dose lower than 0.1 mM. 12-O-Tetradecanoylphorbol-13-acetate, a protein kinase-C (PKC)-activating phorbol ester, which by itself had little effect on 45Ca2+ influx, significantly reduced the ATP-induced 45Ca2+ influx in a dose-dependent manner in the range between 1 nM and 0.1 microM. However, 4 alpha-phorbol 12, 13-didecanoate, a PKC-nonactivating phorbol ester, had little effect on the 45Ca2+ influx induced by ATP. Staurosporine, an inhibitor for PKC, significantly enhanced the ATP-induced 45Ca2+ influx. Pertussis toxin inhibited the ATP-induced formation of IP3 in a dose-dependent manner in the range between 0.1 ng/ml and 1 microgram/ml. On the other hand, pertussis toxin significantly enhanced the ATP-induced 45Ca2+ influx. These results strongly suggest that extracellular ATP-induced Ca2+ influx is autoregulated due to the activation of PKC resulting from pertussis toxin-sensitive GTP-binding protein-coupled phosphoinositide hydrolysis in PC12 pheochromocytoma cells.

Adenosine Triphosphate↗
PubMed1993

[Relationship between lymphocyte subsets of the peripheral blood and noise induced hearing loss].

Biochemical examination and two-color flow cytometric analysis of lymphocyte subsets of the peripheral blood were carried out in 107 healthy males working in high noise environments. The level of hearing disorder was compared with these results. By audiometry at six frequency levels, 51 of the 107 healthy males showed hearing loss. Their mean value of hearing ability was 30 dB and/or above. Among the peripheral lymphocyte subsets, helper T cells of CD4+CD45R- were significantly increased and the CD4/CD8 ratio tended to be elevated. CD20 that indicate B cells were reduced. These results suggested a relationship between susceptibility to acoustic trauma and cell-mediated immunity.

Adult↗
PubMed1993

[Efficacy of the treatment of gastric cancer as neo-adjuvant chemotherapy of 48 hour continuous intravenous infusion of 5-fluorouracil (5-FU) with leucovorin (LV)].

A 51-year-old female with inoperable gastric cancer and with infiltration of pancreatic tail diagnosed by abdominal CT was treated with leucovorin (LV) and 5-fluorouracil (5-FU). The regimen was: LV 30 mg/body/24 hr prior to 5-FU 1,000 mg/m2/day for 48 hrs. This treatment was repeated 6 times. After treatment, the size of tumor decreased so that the patient was able to be operated (Total gastrectomy with partial distal pancreatico-splenectomy). During the treatment, patient showed no side effect except for slight nausea. This neo-adjuvant chemotherapy might be a recommendable treatment of advanced gastric cancer.

Adenocarcinoma↗
PubMed1993

[Effect of nitroprusside on gap junctions of single tracheal smooth muscle cells excised from rats].

To investigate the effect of nitroprusside on gap junctions of tracheal smooth muscle cells, we ionophoretically injected sodium nitroprusside into single tracheal smooth muscle cells excised from rats. The input resistance of the tracheal smooth muscle cells increased after the injection of nitroprusside. This results suggests that nitroprusside blocks gap junctions of tracheal smooth muscle cells.

Animals↗
PubMed1993

PAF-releasing factor in human serum and inflammatory exudate.

A factor responsible for releasing PAF produced in stimulated human polymorphonuclear leukocytes, which had been previously reported in human serum (Miwa et al. (1992) J. Immunol. 148, 872-880), was also confirmed to be present in inflammatory exudate. PAF-releasing factor, partially purified from human serum, was shown to possess higher affinity for PAF than for triacylglycerol, cholesterol ester, fatty acid or phosphatidylcholine. PAF bound to this factor aggregated washed rabbit platelets to the same extent as that bound to BSA, but was difficult to be hydrolyzed using PAF acetylhydrolase. These observations strongly suggest that PAF-releasing factor functions as a PAF carrier in blood and in the inflammatory response.

Carrier Proteins↗
PubMed1993

[A modification of the Aulhorn flicker test with results of physiological and pathological conditions].

The Aulhorn flicker test measures the subjective brightness of various frequencies of flickering light. We modified an Aulhorn flicker test with light emitting diode (LED) and the results of 21 normal eyes and 18 affected eyes (7 eyes with idiopathic optic neuritis, one eye with rhinogenous optic neuropathy (ethmoid sinus mucocele), two eyes with preoperative pituitary tumor, one eye with empty sella, one eye with anterior ischemic optic neuropathy, one eye with syphilitic optic neuritis, five eyes with primary open angle glaucoma) were presented. All normal eyes showed the Brücke-Bartley effect which refers to an enhanced subjective brightness at lower frequencies. Six eyes with idiopathic optic neuritis and one eye with rhinogenous optic neuropathy in the acute stage demonstrated the Aulhorn effect which refers to a reduced subjective brightness at lower frequencies. Four eyes with the Aulhorn effect that were followed up showed less prominent Aulhorn effect. One eye with idiopathic optic neuritis and 10 eyes with other conditions did not show the Aulhorn effect. It was suggested that the modified Aulhorn flicker test with LED is a useful method for diagnosis of optic neuritis in the acute stage.

Adult↗
PubMed1992

The exposure of carcinogen-initiated primary neonatal rat hepatocytes to tumor promoters modulates both the transcripts and the enzymatic activity of nuclear poly(ADP-ribose) polymerase.

Four tumor promoters, i.e. PB, TPA, NAF, and DDT, added singly to a calcium-deprived synthetic medium, elicited early and late mitogenic effects and concurrent surges of nuclear poly(ADP-ribose) polymerase (pADPRP) activity in primary neonatal rat hepatocytes mutagenized with an intra-uterine dose of DMN. These actions were fully abated by the pADPRP inhibitor 3-MBA. Conversely, EGF only acted as a full mitogen when medium's calcium was at physiological levels, and its effects could not be blocked by 3-MBA. The same tumor promoters, but not EGF, also evoked a swift and lingering amplification of pADPRP transcripts in DMN-initiated hepatocytes kept in low-calcium medium. Hence, a coordinated modulation of both pADPRP transcripts and activity by xenobiotics is likely to be involved in the clonal expansion of early preneoplastic hepatocytes.

Animals↗
PubMed1992

Increase of poly(ADP-ribose) polymerase mRNA levels during TPA-induced differentiation of human lymphocytes.

The non-mitogenic stimulation of human peripheral blood mononuclear cells (PBMC) with low concentrations of the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) caused a progressive increase in the percent fraction of the cells that were positive for the early activating antigen CD69. At the same time, it caused a progressive increase in the steady-state levels of poly(ADP-ribose) polymerase (pADPRP) transcripts. A further increase in TPA concentration, while inducing the maximal expression of the levels of CD69 activating surface antigen, both in the presence or in the absence of proliferative activity, did not evoke any additional hightening of pADPRP mRNA levels. Time course of PBMC stimulation with a non-mitogenic dose of TPA showed an early increase in the accumulation of pADPRP mRNA, which changed at 8-16 h, and remained high for several days thereafter. On the basis of these data, we suggest that the increase in pADPRP mRNA may be associated with the commitment of human lymphocytes from a quiescent (G0) to an activated (G1) state.

Blotting, Northern↗
PubMed1992

Release of newly synthesized platelet-activating factor (PAF) from human polymorphonuclear leukocytes under in vivo conditions. Contribution of PAF-releasing factor in serum.

The behavior of platelet-activating factor (PAF) produced in stimulated human polymorphonuclear leukocytes (PMN) was investigated in the presence of serum under conditions close to those existing in vivo. When the cells were stimulated in the presence of the serum obtained from a PAF acetylhydrolase (PAF-AH)-deficient Japanese subject, over 60% of synthesized PAF was detected in the extracellular medium by bioassay, scintillation proximity RIA and selected ion monitoring/gas chromatography/mass spectrography analysis. The release of PAF from PMN after stimulation with FMLP and A23187 was also observed in the presence of normal serum treated with acid to inactivate PAF-AH. The heterogeneity of the molecular species of extracellular PAF was similar to that of intracellular PAF produced in stimulated PMN in the presence of PAF-AH-deficient serum, ruling out the possibility that a specific molecular species of PAF was preferentially released from the cells in the presence of the serum. As these data suggested the occurrence of PAF-releasing factor(s) in the serum, an attempt was made to partially purify this factor from PAF-AH-deficient serum and acid-treated normal serum by ammonium sulfate fractionation and column chromatography with DEAE-Cellulofine and Sepharose CL-6B. The molecular mass of PAF-releasing factor revealed on a TSK gel G3000 SW HPLC column was 240 kDa, which was different from that of albumin. The binding assay, newly developed for this study, revealed that the PAF-binding activity of PAF-releasing factor is stronger than that of albumin, and that the PAF-releasing factor forms a complex with PAF at low concentration (10(-9) M). PAF bound to this factor was difficult to be hydrolyzed by serum PAF-AH. On the other hand, the PAF/PAF-releasing factor complex had aggregatory activity toward washed rabbit platelets. These observations suggest that certain protein(s) releases and carries the PAF newly synthesized by PMN in blood plasma/serum. Thus it appears that PAF functions as an autacoid in vivo, along with other mediators.

Calcimycin↗
PubMed1992

Influence of poly(ADP ribose) polymerase depletion on promotion of liver carcinogenesis.

In previous studies we demonstrated that liver poly(ADP ribose) polymerase (pADPRP) activity was lost in animals exposed to N-2-acetylaminofluorene (2AAF) according to the Teebor and Becker experimental model (Cancer Res 31:1-3, 1971). In addition, we used the resistant hepatocyte model of Solt and Farber (Nature 263:702-703, 1976) to further investigate pADPRP activity during the multistep process of liver carcinogenesis. A marked depletion of the catalytic protein was evidenced after 2AAF exposure, confirming previous results and indicating a specific effect of 2AAF on this nuclear enzyme that controls conformational changes of chromatin and regulates several catalytic activities in the nucleus. The levels of pADPRP mRNA, measured by northern blot analysis using both experimental models, indicate that the enzyme depletion is not due to a loss of transcript. Moreover, these data indicate that pADPRP depletion, caused by 2AAF, was also maintained during liver compensatory growth, which is known to induce a rapid and marked increase in pADPRP activity and protein level. Treatment of 2AAF-exposed animals with N-acetyl-L-cysteine not only efficiently protected against DNA damage, but also prevented a rapid depletion of the catalytic protein. Interestingly, these data indicate that the marked loss of liver pADPRP occurred during the promotion step induced by 2AAF feeding and that this loss was observed using different models for experimental hepatocarcinogenesis. This phenomenon can be ascribed to a highly defective transcript that cannot be correctly translated into the specific protein or to a rapid degradation of the translated protein.

2-Acetylaminofluorene↗
PubMed1992

Cross-talk regulation between cyclic AMP production and phosphoinositide hydrolysis induced by prostaglandin E2 in osteoblast-like cells.

In cloned osteoblast-like MC3T3-E1 cells, PGE2 stimulated both cAMP accumulation and the formation of inositol trisphosphate (IP3) dose dependently. The cAMP accumulation showed the peak value at 5 min and decreased thereafter, whereas the IP3 formation reached a plateau almost within 10 min and sustained it up to 30 min. The effect of PGE2 on cAMP accumulation (EC50 was 80 nM) was more potent than that on IP3 formation (EC50 was 0.8 microM). 12-O-Tetradecanoyl-phorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, reduced the PGE2-induced cAMP accumulation, whereas 4 alpha-phorbol 12,13-didecanoate, a PKC-nonactivating phorbol ester, had little effect on the cAMP accumulation. 1-Oleoyl-2-acetyl-glycerol, a specific activator for PKC, inhibited PGE2-induced cAMP accumulation. TPA had little effect on cAMP accumulation induced by forskolin or NaF, a GTP-binding protein activator. So, the effect of TPA is presumed to be exerted at the point between the PGE2 receptor and Gs. On the other hand, forskolin and dibutyryl cAMP had little effect on the IP3 formation stimulated by PGE2. H-7, a PKC inhibitor, enhanced the PGE2-induced cAMP accumulation in comparison with HA1004, a control for H-7. Our data suggest that PGE2 regulates cAMP production through self-induced activation of PKC. These results strongly suggest that there is an autoregulatory mechanism in PGE2 signaling, and PGE2 modulates osteoblast functions through a cross-talk interaction between cAMP production and phosphoinositide hydrolysis in osteoblast-like cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Activation of protein kinase C inhibits 45Ca-accumulation in cultures of osteoblast-like cells: possible involvement of insulin-like growth factor-I.

In a previous report, we have demonstrated that exogenous insulin-like growth factor-I (IGF-I) stimulates 45Ca-accumulation into extracellular matrix in long-term cultures of osteoblast-like MC3T3-E1 cells and that 45Ca-accumulation occurs even in the cultures without exogenous IGF-I. In this study, effects of protein kinase C (PKC) on IGF-I secretion and 45Ca-accumulation into extracellular matrix were examined in 6-week cultured MC3T3-E1 cells. The MC3T3-E1 cells secreted IGF-I spontaneously. The PKC activator, 12-O-tetradecanoylphorbol-13-acetate (TPA) suppressed IGF-I secretion in a dose-dependent manner. 4 alpha-Phorbol 12,13-didecanoate (4 alpha-PDD), which is inactive for PKC, had little effect on the secretion. 1-Oleoyl-2-acetylglycerol, a specific activator for PKC, also suppressed the IGF-I secretion dose dependently. H-7, a PKC inhibitor, recovered the inhibitory effect of TPA. On the other hand, TPA inhibited the 45Ca-accumulation into extracellular matrix in cultures of these cells dose dependently, whereas 4 alpha-PDD was ineffective in this capacity. The TPA-induced inhibition of 45Ca-accumulation was recovered almost to the control level by H-7. Exogenous IGF-I recovered the inhibitory effect of TPA on 45Ca-accumulation. In spite of the inhibitory effects of TPA as above, TPA had little effect on DNA synthesis in these cells. These results suggest that the activation of PKC inhibits calcification via suppression of IGF-I secretion in osteoblast-like cells.

Animals↗
PubMed1992

Autoregulation of prostaglandin E2-induced Ca2+ influx in osteoblast-like cells: inhibition by self-induced activation of protein kinase C.

In cloned osteoblast-like MC3T3-E1 cells, prostaglandin E2 (PGE2) stimulated 45Ca2+ influx even in the presence of nifedipine, a Ca2+ antagonist that inhibits voltage-dependent Ca2+ channel, in a dose-dependent manner, attaining a maximum at 0.5 microM. Dose of PGE2 above 0.5 microM caused less than maximal stimulation. While PGE2 stimulated the formation of inositol trisphosphate dose dependently in the range between 1 nM and 10 microM. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, which by itself had little effect on 45Ca2+ influx, significantly suppressed the 45Ca2+ influx induced by PGE2 in a dose-dependent manner between 1 nM and 1 microM. 4 alpha-Phorbol 12,13-didecanoate, a phorbol ester which is inactive for PKC, showed little effect in this capacity. Staurosporine, a PKC inhibitor, enhanced the PGE2-induced 45Ca2+ influx. On the other hand, dibutyryl cAMP had little effect on the 45Ca2+ influx induced by PGE2. Our data suggest that PGE2 regulates Ca2+ influx through self-induced activation of PKC. These results indicate that there is an autoregulatory mechanism in signal transduction by PGE2, and PGE2 modulates osteoblast functions through the interaction between Ca2+ influx and phosphoinositide hydrolysis in osteoblast-like cells.

Animals↗