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Biomedical subjects

K Utsumi

Publications and source records attributed to K Utsumi.

At least 109 records · Page 6Linked to original sources
PubMed1996

Functional role of ventral respiratory group expiratory neurons during vocalization.

The activities of expiratory neurons of the caudal ventral respiratory group (cVRG) (n = 31) were recorded extracellularly during vocalization in unanesthetized, decerebrate cats. Vocalization was induced by electrical stimulation (0.2 ms, 20-80 microA, 100 Hz, lasting for 2-5 s) of the periaqueductal gray (PAG). The firing rates of more than two-thirds of the neurons (24/31) increased during periods of vocalization induced by stimulation of the PAG, with an increase in abdominal muscle activities. The axons of most of these neurons (19/24) projected to the contralateral lumbar spinal cord, and one-third of the bulbospinal neurons (6/19) were orthodromically activated by stimulation of the PAG. Even after sectioning of the axons of bulbospinal cVRG neurons by midsagittal lesion between the obex and the C1 spinal cord, stimulation of the PAG still induced adduction of the vocal cords and vocalization. However, activities of abdominal muscles during vocalization were abolished. These results indicate that the efferent signals for vocalization from the PAG may be relayed at the cVRG neurons and converted into adequate activation of these neurons, contributing to the activation of the abdominal muscles for vocalization.

Abdominal Muscles↗
PubMed1996

Genetic engineering of the processing site of D1 precursor protein of photosystem II reaction center in Chlamydomonas reinhardtii.

The D1 protein (D1) of photosystem II (PSII) reaction center is synthesized as a precursor (pD1) and then processed at its carboxyl terminus to establish the function of water cleavage. The amino acid sequence of the carboxyl terminal extension excised by this process is poorly conserved except for a residue after the cleavage site at position of 345. We have constructed a vector for site-directed mutagenesis of the chloroplast psbA gene encoding D1 of the green alga, Chlamydomonas reinhardtii. The vector enables one to transform the chloroplasts of a psbA deletion mutant (Fud7) and directly select transformants for resistance to spectinomycin. Using this transforming vector, we have substituted Ser345 to Gly, Cys, Val and Phe in order to investigate effects of the amino acid side chain at this position on the processing rate. All of the resulting transformants exhibited the PSII activity as wild type and grew normally under photoautotrophic conditions even under strong light where rapid turnover of D1 protein is expected to occur. Western blotting analysis demonstrated that mature D1 accumulates in these transformants at wild type level. Pulse and chase labeling of chloroplast-encoded proteins using [35S] sulfate revealed that the processing of D1 precursor protein occurs in all four transformants as efficiently as in wild type, at least under the experimental conditions examined. The results suggest that either the amino acid side chain at position of 345 (+1 position) is not crucial to the enzymatic cleavage of pD1 in vivo or the apparent rate of processing in vivo is not limited by the enzymatic cleavage.

Animals↗
PubMed1996

Oxygen-dependent-regulation of Ehrlich ascites tumor cell respiration by nitric oxide.

Effects of nitric oxide (NO) on oxygen uptake of Ehrlich ascites tumor cells (EATC) were examined in a study of the biological actions of NO on respiration and energy metabolism at the cellular level. Endogenous respiration of EATC was inhibited reversibly by NO in a dose dependent manner. Oxyhemoglobin, an NO trapping agent, restored the respiration promptly. The inhibitory action of NO also depended on oxygen-concentration, and the duration of suppression was prolonged remarkably at low oxygen tension. Similar inhibition was also observed in the presence of glucose. In this case, both lactate production and glucose consumption were promoted by NOC 18, an NO generating agent, and the activation was enhanced by lowering the oxygen-concentration. Furthermore, the membrane potential of EATC was depolarized transiently by adding NO, and the degree of depolarization was decreased in the presence of glucose. These results suggest that at physiologically low oxygen tension in ascites fluid, NO acts not only as a cytotoxic respiratory inhibitor but also as a regulatory factor in the energy metabolism of EATC.

Animals↗
PubMed1996

Oxygen-dependent reversible inhibition of mitochondrial respiration by nitric oxide.

Effects of nitric oxide (NO) and NO generating agents, on the electron transport system of mitochondria were examined in a study of the mechanism and physiological importance of NO in energy metabolism. In the presence of various substrates, uncoupled respiration was inhibited by NO in manner which was both dose- and oxygen tension-dependent. Simultaneously measuring changes in cytochrome absorption spectra and respiration showed that the site of action of NO is cytochrome oxidase. Similar inhibition was also brought about by 1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene (NOC 18), an NO donor. Electron paramagnetic resonance (EPR) analysis revealed that inhibition of uncoupled respiration occurred only during the presence of NO in the reaction mixture. The inhibitory effect of NO was increased significantly by lowering the concentration of mitochondrial protein. No appreciable inhibition of respiration was observed in the presence of 3-morpholinosydnonimine (SIN-1), a peroxynitrite anion (ONOO-) generating reagent, but inhibition did occur in the presence of superoxide dismutase (SOD). These results indicate that NO reversibly interacts with mitochondria at complex IV thereby inhibiting respiration particularly under physiologically low oxygen tension and that de novo generated ONOO may have no significant effect under the present experimental conditions.

Animals↗
PubMed1996

Inhibition of neutrophil-superoxide generation by alpha-tocopherol and coenzyme Q.

Effects of various derivatives of alpha-tocopherol (VE) and coenzyme Q (CoQ) on superoxide (O2.-) generation of neutrophils and protein kinase C (PKC) activity were examined. VE and CoQ8 inhibited O2.- generation of neutrophils stimulated by a protein kinase C mediated process monitored by cytochrome c reduction and spin trapping methods. The inhibitory action was observed not only with alpha-tocopherol, but also with beta-, gamma-, delta-tocopherols and with tocol which is a chemical similar to VE but lacking methyl groups on the chromanol ring structure and which is not a radical scavenger. By contrast, no inhibition was observed with 2-carboxy-2, 5, 7, 8-tetramethyl-6-chromanol (CTMC, trolox) or 2, 2, 5, 7, 8,-pentamethyl-6-chromanol (PMC) which are water soluble VE derivatives having radical scavenging activity. Compounds having a similar isoprenoid chain, such as CoQ, also have inhibitory activity on PKC-dependent O2.- generation of neutrophils. The inhibitory activity of CoQ derivatives is dependent on the length of the unsaturated isoprenoid chain. CoQ derivatives having 16, 24 and 32 carbon isoprenoid chains corresponding to CoQ4, 6, and 8 inhibited O2.- generation but 4 and 40 carbon isoprenoid chains corresponding to CoQ2 and 10 had no inhibitory activity on O2.- generation. Alpha-tocopherol and CoQ inhibited PKC activity but the ID50 for O2.- generation and PKC activity was different for each compound. However, no direct relationship between VE content and O2.- generation of neutrophils was observed. These results suggest that isoprenoids of VE and CoQ participate in the inhibition of the NADPH oxidase activation system through modulation of the neutrophil membrane probably by the inhibition of PKC.

Animals↗
PubMed1996

Oxygen-dependent inhibition of neutrophil respiratory burst by nitric oxide.

Effect of nitric oxide (NO) on the respiratory burst of neutrophils was examined under different oxygen tensions. Phorbol myristate acetate (PMA) stimulated oxygen consumption and superoxide (O2) generation in neutrophils by a mechanism which was inhibited reversibly by NO. The inhibitory effect of NO increased significantly with a decrease in oxygen tension in the medium. The inhibitory effect of NO was suppressed in medium containing oxyhemoglobin (HbO2), a NO scavenging agent. In contrast, 3-morpholinosydnonimine (SIN-1), a compound that rapidly generates peroxynitrite (ONOO-) from the released NO and O2-, slightly stimulated the PMA-induced respiratory burst. These results suggested that NO, but not ONOO-, might reversibly inhibit superoxide generation by neutrophils especially at physiologically low oxygen tensions thereby decreasing oxygen toxicity particularly in and around hypoxic tissues.

Animals↗
PubMed1996

[Lymphocyte subsets in bronchoalveolar lavage fluid from patients with idiopathic interstitial pneumonia].

Lymphocyte activation may be involved in interstitial inflammatory processes in the lungs. We analyzed lymphocytes in bronchoalveolar lavage fluid obtained from 15 patients with idiopathic interstitial pneumonia (IIP) and from 7 controls. Clinical criterial were used to divide the patients with IIP into two groups: acute (n = 5) and chronic (n = 10). Lymphocytes in the bronchoalveolar lavage fluid were analyzed with a flow-cytometric two-color system. Differential cell counts showed that percentages and numbers of lymphocytes were significantly higher in patients with acute IIP (44.2 +/- 25.2%, 12.3 +/- 8.18 x 10(4)/ml) than in controls (8.31 +/- 3.66%, 0.69 +/- 0.39 x 10(4)/ml, p < 0.05) and in patients with chronic IIP (8.44 +/- 6.11%, 1.58 +/- 1.08 x 10(4)/ml, p < 0.05). In particular, percentages and numbers of CD8+ S6F1+ lymphocytes, which are regarded as activated cytotoxic T lymphocytes were markedly higher in patients with acute IIP (32.3 +/- 16.0%, 39.6 +/- 37.1 x 10(3)/ml), than in controls (6.31 +/- 1.69%, 0.42 +/- 0.25 x 10(3)/ml, p < 0.05) and in patients with chronic IIP (10.6 +/- 6.16%, 1.88 +/- 1.42 x 10(3)/ml, p < 0.05). These data suggest that patients with acute IIP differ from those with chronic IIP in the percentage and the number of lymphocytes in bronchoalveolar lavage fluid, and that activated cytotoxic T lymphocytes may play an important role in the pathogenesis of acute IIP.

Acute Disease↗
PubMed1996

[Sulfamethoxazole-trimethoprim-induced pneumonitis in a patient with hemophilia B who was infected with the human immunodeficiency virus].

Severe cellular immunosuppression developed in a 25-year-old man with hemophilia B who was infected with the human immunodeficiency virus (HIV). Four days after administration of sulfamethoxazole-trimethoprim (SMX-TMP) for prophylaxis against Pneumocystis carinii pneumonia (PCP), diffuse uptake of both lungs was confirmed on a 67Ga scintigram. Reticular shadows were also seen throughout both lung fields on a chest CT scan. These findings were compatible with PCP, according to the guidelines for presumptive diagnosis of the acquired immunodeficiency syndrome, published by the Centers for Disease Control and Prevention. The dose of SMX-TMP was increased, but interstitial pneumonitis worsened and was accompanied by fever, skin rash, and liver dysfunction, which are common in HIV-infected patients receiving SMX-TMP. No evidence of PCP or of any other opportunistic infection was found by bronchoalveolar lavage. Adverse reactions diminished after SMX-TMP administration was stopped. The 67Ga scintigram and chest CT findings also returned to normal. We concluded that the interstitial pneumonitis was induced by SMX-TMP. SMX-TMP is the first choice anti-PCP drug, but a high incidence of adverse reactions in patients with HIV infection has been reported. Therefore the possibility of SMX-TMP-related pulmonary toxicity must be considered in HIV-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed1996

[Relationship between SPECT and pathological alterations in Alzheimer's disease--a study of a case with left-hemisphere dominant lesions].

123I-IMP SPECT (SPECT) has been widely used in clinical neuropsychiatry for establishing the clinical diagnosis, and evaluating the course of the disease. However, little is known about the significance of alterations in SPECT. In this paper, we present comparative study between alterations in SPECT and neuropathological findings in the case of Alzheimer's disease (AD). The patient, a 59-year-old female, began to show memory disturbance and the left hemisphere disturbances, non-fluent aphasia, but right hemisphere disturbances, constructional apraxia, visuo-spatial dysfunctions were not notable at the early stage. The neuroimaging also revealed left-side dominant cerebral atrophy in MRI and left-side dominant hypoactive regions in SPECT (especially in parietal lobe). Memory disturbance and non-fluent aphasia gradually progressed after admission. Then, mirror phenomenon and Bálint's syndrome appeared at the age of 63 years. In the advanced stage, hypoactive regions in SPECT were expanded into temporal and frontal areas. The laterality observed at the early stage became unremarkable. The patient died from heart failure at 64 years. Pathological diagnosis was AD. Eleven ROI (region of interests) were determined on each hemisphere in transverse SPECT image. We calculated ROI% (each ROI count/ROI count at central cerebellum). Neuronal cell count (NCC) and amyloid beta protein deposited areas (BDA) were estimated using 3 serial sections stained with Nissl's method and immunostained for amyloid using monoclonal antibody raised against synthetic A beta, mcAb 90/12. Digitized images based on photographs were analyzed with NIH-image 1.45. NCC decreased in number in frontal, temporal, and parietal lobes. Significant asymmetrical reduction of NCC (lt. < rt.) was observed in orbital, superior temporal and angular gyri (p < 0.01). BDA in superior parietal lobule, superior temporal gyrus and superior, middle, inferior frontal gyri were larger than those in precentral gyrus and visual cortex. Asymmetry of BDA (lt. > rt.) was significant in middle temporal gyrus (p < 0.01). ROI% at the early stage was correlated with corresponding NCC (r = 0.49, p < 0.05) and BDA (r = -0.55, p < 0.01), but at the advanced stage was not significantly correlated with corresponding NCC (r = 0.26) and BDA (r = -0.20). It is evident that SPECT shows good correlation with clinical features and pathological alterations during the course of AD. Our observations imply that the changes in SPECT usually precede the appearance of the clinical symptoms. SPECT is very sensitive in detecting the functional decline in certain regions of the CNS. In the case of AD, the hypoactive regions in SPECT at the early stage may indicate functional decline of the neuronal cells, and at the advanced stage, these may indicate the degree of pathological changes, especially neuronal loss and amyloid beta protein deposition.

Alzheimer Disease↗
PubMed1996

Nitric oxide, a physiological modulator of mitochondrial function.

The effect of nitric oxide (NO) on the energy transfer reactions of mitochondria was examined under different oxygen tensions. Mitochondrial functions, such as respiration, ATP synthesis and regulation of membrane potential, were inhibited by NO in a concentration-dependent manner. In the presence of various substrates, NO also inhibited uncoupled respiration in an oxygen concentration-dependent manner. The inhibited function recovered completely at certain times after adding NO. When added to mitochondrial suspensions, NO disappeared rapidly from the medium and more rapidly at high oxygen tensions than at low oxygen tensions as determined by the formation of methemoglobin and EPR methods. From these results it is concluded that NO might play an important role in the regulation of mitochondrial functions particularly under low oxygen concentrations.

Animals↗
PubMed1995

Inhibition of neutrophil superoxide generation by hypericin, an antiretroviral agent.

We previously reported that phorbol 12-myristate 13-acetate (PMA)-induced superoxide (O2.-) generation of neutrophils was inhibited by hypericin, a photosensitizing pigment found in St. Johnswort (herb Hypericin triquetrifolium Turra), via a mechanism involving protein kinase C (PKC). To obtain further insights into the mechanism of inhibition, the effects of hypericin on stimulation-dependent O2.- generation and related enzymes of neutrophils were investigated. Hypericin inhibited O2.- generation of neutrophils induced by PKC-dependent and -independent stimuli in a light- and concentration-dependent manner. Oxygen was required for the light-dependent inhibition by hypericin. NADPH oxidase activity in a cell-free system and TNF-alpha-induced tyrosyl phosphorylation of neutrophil proteins were also inhibited by hypericin in a concentration- and light-dependent manner. However, tyrosine kinase of p60src, an enzyme not bound to a membrane, was not inhibited either in the light or in the dark. Oxygen uptake of neutrophils by photosensitization with hypericin resulted in the formation of singlet oxygen (1O2), O2.-, and hydroxyl radical (.OH) and enhanced lipid peroxidation. The formation of 1O2 was inhibited by azide, a quencher of 1O2, but not by desferrioxamine (DSF), a ferric ion chelator. By contrast, both generation of .OH and lipid peroxidation were inhibited by DSF but not by azide. Furthermore, PMA-induced O2.- generation inhibited by hypericin partially recovered in the presence of azide but not DSF. These results suggested that the light-dependent inhibition of O2.- generation by hypericin might be due to inhibition of tyrosine kinase, PKC, and NADPH oxidase via an oxygen-dependent mechanism, possibly through both Type I and II photosensitization mechanisms.

Anthracenes↗
PubMed1995

Oxygen-dependent regulation of mitochondrial energy metabolism by nitric oxide.

To elucidate the role of nitric oxide (NO) in the regulation of mitochondrial function, the effect of NO on energy transfer reactions was examined under different oxygen tensions. Mitochondrial respiration was remarkably inhibited by NO resulting in the inhibition of ATP synthesis in a concentration-dependent manner. In the presence of succinate, respiration, respiratory control by ADP, and ATP synthesis recovered completely at certain times after adding NO. The inhibitory action of NO continued significantly longer under physiologically low oxygen concentrations (such as the cytosolic level) than at high concentrations. In the presence of various substrates, such as pyruvate malate, succinate, and ascorbate tetramethyl paraphenylenediamine, NO also inhibited the uncoupled respiration in an oxygen- and concentration-dependent manner. The inhibition of respiration by NO was stoichiometrically suppressed by oxyhemoglobin. When added to a mitochondrial suspension, NO rapidly disappeared from the medium particularly at high oxygen tension. However, the rate of NO disappearance was significantly lower under low oxygen tension. Thus, under cytosolic oxygen concentration, NO might play an important role in the regulation of mitochondrial energy metabolism.

Adenosine Triphosphate↗
PubMed1995

Effect of the antiretroviral agent hypericin on rat liver mitochondria.

The photosensitizing effect of hypericin (HY), an antiretroviral agent, on the functions of isolated rat liver mitochondria has been investigated. The respiratory control ratio (RCR), ADP/O and membrane potential of mitochondria were decreased by HY in a light-dependent manner. Uncoupled respiration of mitochondria in the presence of succinate was also inhibited by HY in a light-dependent manner. The ID50 of hypericin for these inhibitions was approximately 0.5 microM. These inhibitory effects of HY were not observed when photosensitization was conducted under anaerobic conditions and were not affected by desferrioxamine (DSF) or superoxide dismutase (SOD). Upon photosensitization of HY, mitochondria consumed oxygen in the absence of respiratory substrate with concomitant formation of thiobarbituric acid reactive substance (TBARS). The amount of oxygen consumed was 100-times greater than that of TBARS formed. The oxygen uptake was partially inhibited by NaN3, and formation of TBARS was inhibited by DSF. Upon photosensitization of HY in the presence of mitochondrial membranes, the electron spin resonance (ESR) signal of 2,2-dimethyl-5-hydroxy-1-pyrrolidinyloxyl (DMPO/.OH) was increased by a mechanism which was suppressed by DSF. An ESR signal for singlet oxygen bound to 2,5-dimethylfuran, 2,2,6,6-tetramethyl-4-piperidone (TEMP) was also detected under light in the presence of mitochondria. This signal of the TEMP-N-oxyl radical (TEMPO) was decreased by azide, which physically quenches singlet oxygen, but was increased by DSF. These results indicate that HY might inhibit mitochondrial functions by a type II photodynamic mechanism but that lipid peroxidation of biological membranes through an active oxygen-mediated photodynamic mechanism is not involved.

Animals↗
PubMed1995

Okadaic acid increased annexin I and induced differentiation of human promyelocytic leukemia cells.

The differentiation of a cell line of human promyelocytic leukemia, HL-60 cells, triggered by 12-O-tetradecanoyl 13-phorbol acetate (TPA), depends on the phosphorylation of some proteins, such as 17, 27, and 34 kDa proteins, by protein kinase C. For elucidation of the mechanism of ligand-induced differentiation of HL-60 cells, the effects of okadaic acid (OA), a phosphatase inhibitor, on cell differentiation and protein phosphorylation were studied. After treatment with OA, HL-60 cells differentiated into macrophage-like cells; within 16 h, 70% or more of the treated cells adhered to plastic dishes. The adherent cells did not undergo mitosis but began activities such as phagocytosis. OA increased the phosphorylation of 17, 23, 27, and 34 kDa proteins, as did TPA. The amount of annexin I (39 kDa protein) in HL-60 cells caused to differentiate with OA was 7.5-fold that without such treatment. Kinetic analysis showed that increased transcription of annexin I mRNA caused the increase in annexin I in the differentiated cells. Thus, OA and TPA increased cellular levels of annexin I and caused the differentiation of HL-60 cells into macrophage-like cells.

Annexin A1↗
PubMed1995

Photoactivated inhibition of superoxide generation and protein kinase C activity in neutrophils by blepharismin, a protozoan photodynamically active pigment.

Blepharismin is an endogenous photosensitizing pigment found in the protozoan Blepharisma. This pigment inhibited the generation of superoxide anion (O2-.) in neutrophils not only via a diacylglycerol-induced protein kinase C (PKC)-dependent reaction but also by an arachidonate-induced PKC-independent reaction. The inhibition was light and concentration dependent for both reactions. Light-activated inhibition was strong at wavelengths between 520 and 570 nm but not above 610 nm. PKC activity in neutrophils and from rat brain was inhibited by blepharismin in a light- and concentration-dependent manner. Moreover, arachidonate-activated NADPH oxidase activity in a cell-free system was also inhibited by the pigment in a light- and concentration-dependent manner. These results suggest that blepharismin inhibits NADPH oxidase activation through the non-specific inhibition of various membrane-bound enzymes and that this inhibition may also be correlated with that of PKC.

Animals↗
PubMed1995

Progression of hormone-dependent adenocarcinoma cells to hormone-independent spindle carcinoma cells in vitro in a clonal spontaneous rat mammary tumor cell line.

A hormone-dependent, clonal carcinoma cell line, designated RM22-F5, was derived from a malignant mammary mixed tumor spontaneously arising in an outbred old female Wistar rat. These cells expressed keratin and desmosomal protein and formed epithelial monolayers in a growth factor and hormone-supplemented medium (LHC-8) containing 10% fetal bovine serum (E-type cells). Cells subcultured for 6 to 8 passages in RPMI 1640 medium containing 10% fetal bovine serum without supplements appeared to be fibroblastic and expressed vimentin (F-type cells). The shift to a fibroblast-like morphology was associated with a more malignant phenotype which included rapid, hormone-independent growth and invasive sarcoma-like character in nude mice. F-type cells were no longer able to express their original epithelial phenotype in LHC-8 medium. Cytogenetic analysis revealed that both E- and F-type cells had essentially the same karyotype. Analysis of PCR-amplified DNA further demonstrated a point mutation of the H-ras-1 gene at codon 12 and loss of the normal H-ras-1 allele in both cell types. Genetic tagging of E-type cells with the neomycin-resistance gene resulted in the generation of F-type cells with neomycin resistance in RPMI 1640 medium, suggesting that F-type cells are a malignant variant of E-type cells arising during in vitro culture. Somatic cell fusion between E- and F-type cells revealed that with most hybrid clones tested, the fibroblast-like phenotype was greatly suppressed. These results suggest that an irreversible phenotypic transition, representative of tumor progression from hormone-dependent adenocarcinoma to more malignant hormone-independent spindle carcinoma cells, is a recessive event and may involve loss of a suppressor function.

Adenocarcinoma↗
PubMed1995

Light-dependent inhibition of protein kinase C and superoxide generation of neutrophils by hypericin, an antiretroviral agent.

Hypericin, a photosensitizing plant pigment, has antiretroviral activity. When exposed to light, the inhibition of Friend leukemia virus (FLV)-induced splenomegaly by hypericin was increased. The ID50 was decreased to less than 2.5 micrograms/mouse by exposure to tungsten light (29 x 10(-3) W/cm2 for 3 min). This pigment inhibited phorbol 12-myristate 13-acetate (PMA)-activated protein kinase C of rat brain in a light- and concentration-dependent manner. The ID50 of hypericin and the light intensity for inhibition of PKC were 0.1 microM under a constant light of 29 x 10(-3) W/cm2 for 3 min and 5 x 10(-3) W/cm2 in the presence of 1 microM hypericin for 3 min, respectively. The PMA-induced respiratory burst of neutrophils was inhibited in the light but stimulated in the dark by hypericin. The ID50 for inhibition of the respiratory burst was similar to that for inhibition of PKC. These results suggest that hypericin might inhibited PKC-mediated processes of intact cells, including PMA-induced superoxide generation of neutrophils by some light-dependent mechanism, and that this mechanism might underlie its light-dependent inhibition of FLV infection.

Animals↗