[Tradition or dogma of the apex beat].
Explore the source record for details and available documents.
Electrocardiography↗
Biomedical subjects
T Sakamoto
Publications and source records attributed to T Sakamoto.
[The limitation of synchronization of pressure support ventilation (PSV) in ARDS].
PSV has been increasingly used as a partial ventilatory support for various types of respiratory failure. We experienced premature breath termination and double triggering in a patient with ARDS during PSV, and investigated the cause of this phenomenon using respiratory muscle pressure (Pmus). The analysis confirmed that the respiratory muscles and the ventilator did not coordinate synchronously in the patient with very low compliance of the respiratory system. The limitation of synchronization was attributable to fixed flow termination criteria in the present PSV algorithm. When dissynchronization is not manageable, other ventilatory modes (eg, APRV, PCV) allowing spontaneous ventilation should be considered as an alternative.
Aged↗
Characterization of an HDV ribozyme which consists of three RNA oligomer strands.
Properties of a mutant hepatitis delta virus (HDV) ribozyme which consists of three RNA oligomer strands (Fig. 1c) are described. Effects of the MgCl2 concentration, pH and temperature on the cleavage reaction were examined. The dependence on these conditions did not resemble those of the published data for other HDV ribozymes (the parent) which consist of single-strand RNA of about 90 nt. The highest cleavage for the mutant was observed at 35-40 degrees C, while the parent ribozymes show higher activity at around 60 degrees C than at 40 degrees C. Thus we suppose that the most of the parent ribozymes are in inactive conformation at 40 degrees C and high temperature is needed to change the equilibrium between the inactive and active conformations. Since the Tm of the mutant was around 50 degrees C, these results suggest that the most of the mutant ribozyme complex molecules are in active conformation at 40 degrees C.
Base Sequence↗
Structure of translation initiation region of c-myc mRNA and thermostability of the c-myc mRNA/antisense ODN complex.
We enzymatically synthesized c-myc mRNA fragment containing the translation initiation (TI) region (36mer) and examined the structure by CD, 1H-NMR and RNaseV1 digestion. These study demonstrated that the c-myc mRNA fragment forms a hairpin structure at 37 degrees C. Six 15-mer antisense oligodeoxynucleotides(ODNs), which hybridize to the c-myc mRNA fragment were designed, and synhesized. Thermostabilities of the antisense ODNs-mRNA fragment complexes were examined. Antisense A (complementary to the c-myc mRNA from -9 to +6)-c-myc mRNA fragment complex had the highest melting temperature(Tm), and Antisense D (complementary to the c-myc mRNA from +1 to +15)-c-myc mRNA fragment complex had the most different Tm from a predicted Tm. Furthermore, Antisense D exhibited high inhibitory effect on HL60 cell proliferation, whereas Antisense A did not. The results suggest that the difference in the antisense effect is not simply due to the complex thermostability.
Cell Line↗
Purification and characterization of a rhamnogalacturonase with protopectinase activity from Trametes sanguinea.
In a culture filtrate of Trametes sanguinea IFO 6490, we found a protopectin-solubilizing enzyme, protopectinase-T, that did not degrade polygalacturonic acid. The enzyme was purified to homogeneity with hydrophobic, cation-exchange, anion-exchange, and size-exclusion chromatographies. It had an apparent molecular mass of 55 kDa by SDS/PAGE and 39 kDa by size-exclusion chromatography on Superose 12. The isoelectric point was at pH 8.1. Protopectinase-T was stable from pH 3.0 to 6.0 and at temperatures up to 50 degrees C. The optimum pH for enzyme activity was 4.0 at 37 degrees C, and the optimum temperature was 50 degrees C at pH 5.0. Protopectinase-T catalyzed the release of highly polymerized pectin from lemon peel protopectin.
Chromatography, Gel↗
delta 9 Acyl-lipid desaturases of cyanobacteria. Molecular cloning and substrate specificities in terms of fatty acids, sn-positions, and polar head groups.
In cyanobacteria, the biosynthesis of unsaturated fatty acids is initiated by delta 9 acyl-lipid desaturase which introduces the first double bond at the delta 9 position of a saturated fatty acid that has been esterified to a glycerolipid. We have cloned genes, designated desC, for delta 9 acyl-lipid desaturases from two cyanobacteria, namely Anabaena variabilis and Synechocystis sp. PCC 6803. These desaturases, when expressed in Escherichia coli, desaturated stearic acid to yield oleic acid at the C-1 positions of phosphatidylethanolamine and phosphatidylglycerol, but did not desaturate palmitic acid, palmitoleic acid, and cis-vaccenic acid. These results indicate that the delta 9 acyl-lipid desaturases are specific to stearic acid esterified at the C-1 position of a glycerolipid and are nonspecific with respect to the polar head group of the glycerolipid. The deduced amino acid sequences of the delta 9 acyl-lipid desaturases are similar in part to those of stearoyl-CoA desaturases of the rat, the mouse, and Saccharomyces cerevisiae, but not to those of acyl-(acyl-carrier-protein) desaturases of higher plants.
Amino Acid Sequence↗
IL-1 beta regulates the expression of the Gi2 alpha gene via lipid mediators in guinea pig tracheal muscle.
When isolated guinea pig muscle preparations were incubated with human recombinant IL-1 beta, mRNA level of Gi2 alpha but not of Gs alpha increased in a time and dose dependent manner. The increase was partially blocked by inhibitors of lipoxygenase (NDGA) and cyclooxygenase (indomethacin) and PAF antagonist (SC47014A), while U46619 (thromboxane A2 mimetic), LTD4, 15-HETE and PAF partially mimicked it. The IL-1 beta induced Gi2 alpha expression was almost completely inhibited by anti-phospholipase A2 antiserum, whereas preimmune serum had no apparent effects. From these observations, we suggest that IL-1 beta first induces the synthesis and release of Type II inflammatory phospholipase A2, which in turn stimulates the expression of Gi2 alpha gene via production of various lipid mediators.
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
Isolation, characterization and structural organization of the gene and pseudogene for the dihydrolipoamide succinyltransferase component of the human 2-oxoglutarate dehydrogenase complex.
In the present study, the dihydrolipoamide succinyltransferase gene of the 2-oxoglutarate dehydrogenase complex was isolated from a human genomic DNA library and its entire nucleotide sequence was determined. This gene was approximately 23 kbp in size with 15 exons and 14 introns. All of the donor and acceptor splice sites of this gene conformed to the GT/AG rule. A guanine residue 43 bases upstreams of the ATG initiating translation codon was the transcription initiation site of the human dihydrolipoamide succinyltransferase mRNA. Sequence analysis of the promoter-regulatory region showed the presence of a CAAT-box-like sequence but the presence of a TATA-box-like sequence was not evidenced. Also located in this region were sequences resembling glucocorticoid-responsive and cAMP-responsive elements, and an Sp1 binding site. No nucleotide sequence corresponding to the E3-binding and/or E1-binding domain was found in any region of the gene. Therefore, the exon coding for the E3-binding and/or E1-binding domain may have been lost from the gene during evolution. Moreover, a processed pseudogene of dihydrolipoamide succinyltransferase was isolated and sequenced. The nucleotide sequence of the pseudogene is 93% similar to the sequence of the human dihydrolipoamide succinyltransferase cDNA, but the pseudogene is not functional for base changes, deletions and insertions of the pseudogene. Southern-blot analysis showed the presence of a single copy of this gene and a single copy of a pseudogene in the human genome. In addition, a possible relationship between dihydrolipoamide succinyltransferase and familial Alzheimer's disease is discussed.
Acyltransferases↗
Dopamine inhibits TRH-induced MAP kinase activation in dispersed rat anterior pituitary cells.
We recently reported the existence of two separate pathways for thyrotropin-releasing hormone (TRH)-induced mitogen-activated protein (MAP) kinase activation in GH3 pituitary tumor cells. To test the role of MAP kinase in TRH action, we examined the effect of dopamine (DA) on TRH-induced MAP kinase in primary cultures of rat anterior pituitary cells. 1 microM of DA attenuated 1 microM TRH-induced MAP kinase activity and phosphorylation. 100 ng/ml of islet-activating protein (IAP) blocked these inhibitory effects of DA. These results suggest that crosstalk exists between the DA signaling pathway and the TRH-stimulated MAP kinase activating pathway in rat anterior pituitary cells.
Adenosine Triphosphate↗
Protopectinase-T: a rhamnogalacturonase able to solubilize protopectin from sugar beet.
Protopectinase-T (PPase-T), isolated from the culture broth of Trametes sanguinea, was able to release pectic substances from sugar beet by degrading rhamnogalacturonan. The smallest polysaccharide (SPS) that can serve as a substrate for PPase-T was prepared from sugar beet pulp by extraction with NaOH and digestion with alpha-L-arabinofuranosidase, alpha-L-arabinase, and beta-(1-->4)-D-galactanase. The reaction products of SPS with PPase-T were isolated by chromatography on DEAE-Toyopearl 650M and Toyopearl HW40-S columns, and analyzed by labeling the reducing ends with [3H]NaBH4 and by 13C NMR spectroscopy. The results indicated that PPase-T cleaved galactopyranosyluronic-rhamnopyranosyl linkages in SPS. Moreover, it was confirmed that the chemical structure of SPS contains a backbone based on units of [-->4)-alpha-D-GalpA-(1-->2)-alpha-L-Rha p-(1-->].
Carbohydrate Conformation↗
The transition of alpha-helix to beta-structure of poly(L-lysine) induced by phosphatidic acid vesicles and its kinetics at alkaline pH.
Static and dynamic circular dichroism (CD) measurements were carried out for poly(L-lysine) in suspensions of dilauroylphosphatidic acid (DLPA) vesicles at alkaline pH (8-11.5). The static experiments demonstrated that the alpha-helix of poly(L-lysine) induced by deprotonation in alkaline solutions is transformed to beta-structure by the addition of DLPA vesicles. Stopped-flow CD measurements for such order-to-order transition revealed that the rate determining step is the unfolding process of alpha-helix to random coil. Previously, we have reported the conformational change of poly(L-lysine) induced by DLPA vesicles at neutral pH, where the beta-structure transition from random coil was observed. Thus two types of transition of poly(L-lysine) are observed depending on bulk pH, i.e., from random coil to beta-structure and from alpha-helix to beta-structure. So far the phospholipid-induced conformations of poly(L-lysine) were interpreted in terms of counterbalance between the positively charged terminals of the lysyl chains and the negative headgroups of the phospholipid in vesicle. However, present work indicates the direct interaction other than electrostatic interaction between the lysyl chain and phosphate groups of the lipid.
Circular Dichroism↗
Dermatome mapping in the rat hindlimb by electrical stimulation of the spinal nerves.
In rats treated with Evans blue (i.v.), electrical stimulation of the lumbar spinal nerves produced an extravasation zone in the skin. Stimulation of L1 produced extravasation in the lower abdomen; that of L2, in the cranial region of the hindlimb; that of L3, in the ventral region of the hindlimb and the medial paw; that of L4, in the lateral region of the hindlimb and the middle paw; that of L5, in the caudal region of the hindlimb and the lateral paw; and that of L6, in the caudal region of the hindlimb and the scrotum. Since the substance P antagonist FK224 inhibited the extravasation caused by stimulation of the sciatic nerve, the extravasation zones appeared to be related to antidromic activation of afferent C-fibers. Thus, a dermatome of afferent C-fibers was revealed in rats.
Afferent Pathways↗
Effect of a bradykinin receptor antagonist, HOE 140, against bradykinin- and vagal stimulation-induced airway responses in the guinea-pig.
We have investigated the effect of inhaled HOE 140, a novel bradykinin B2 receptor antagonist, against bradykinin- and vagal stimulation-induced airway microvascular leakage and bronchoconstriction in anesthetized guinea-pigs. Lung resistance was measured for 6 min after challenge, followed by measurement of extravasation of Evans blue dye into airway tissues, used as an index of airway microvascular leakage. Bradykinin was given by inhalation (1 mM, 45 breaths) and bilateral vagus nerves were stimulated electrically during a 5-min period (3 and 10 Hz, 5 V, pulse width of 5 ms), both of which caused a significant increase in lung resistance and leakage of dye in the airway. HOE 140 (20 and 200 microM, 60 breaths) completely abolished both the airway effects induced by bradykinin, whereas even the higher dose of HOE 140 had no effect against those induced by electrical vagal stimulation. In conclusion, airway microvascular leakage and bronchoconstriction induced by inhaled bradykinin are mediated by activation of bradykinin B2 receptors in the guinea-pig. In contrast, mechanisms via bradykinin B2 receptors do not play an important role in the acute airway responses induced by vagal stimulation.
Administration, Inhalation↗
Production of interleukin-1 by primary cultured parenchymal liver cells (hepatocytes).
The production of interleukin-1 (IL-1) by cultured parenchymal liver cells was revealed by a biological assay with an IL-1-dependent cell line, Northern blot analysis, and in situ hybridization. Inhibition experiments on the IL-1 activity with anti IL-1 alpha antibody also support the presence of IL-1 alpha in the supernatant of cultured parenchymal liver cells. Based on these results, we discuss the possibility of IL-1 production by parenchymal liver cells in vivo.
Animals↗
Subretinal neovascularization in the rat induced by IRBP synthetic peptides.
The present study was undertaken to develop a new animal model of subretinal neovascularization that does not involve traumatic manipulation of the eye. Using this model, the mechanism of subretinal neovascularization and its penetration through Bruch's membrane, and the various factors that contribute to this process were then examined. Male Lewis rats were immunized with interphotoreceptor retinoid binding protein (IRBP) peptide R-4, and the eyes histologically examined at various times up to 45 days after immunization. On day 12 after immunization, inflammatory cells were identified primarily in the anterior segment of the eye, with scattered cells in the retina and choroid. The inflammation was most prominent on day 14, by which time many eyes showed serous retinal detachment. By day 18 the inflammation had declined in intensity, but branches of the retinal vessels were seen extending into the choroid. Examination on day 30 revealed even fewer inflammatory cells but an accumulation of retinal pigment epithelial cells and mononuclear cells was present in the subretinal space. Examination on day 45 revealed no appreciable inflammation, but typical new vessels were found in the eyes from five of the 13 rats (38%) examined at that point. Mild inflammation of the retinochoroidal tissue can induce subretinal new vessels in rats, and this model will be useful for further study of subretinal new vessel formation.
Amino Acid Sequence↗
Identification of conserved domains in the delta 12 desaturases of cyanobacteria.
Cyanobacterial genes for enzymes that desaturate fatty acids at the delta 12 position, designated desA, were isolated from Synechocystis PCC6714, Synechococcus PCC7002 and Anabaena variabilis by cross-hybridization with a DNA probe derived from the desA gene of Synechocystis PCC6803. The genes of Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis encode proteins of 349, 347 and 350 amino acid residues, respectively. The transformation of Synechococcus PCC7942 with the desA genes from Synechocystis PCC6714, Synechococcus PCC7002 and A. variabilis was associated with the ability to introduce a second double bond at the delta 12 position of fatty acids. The amino acid sequence of the products of the desA genes revealed the presence of four conserved domains. Since one of the conserved domains was also found in the amino acid sequences of omega 3 desaturases of Brassica napus and mung bean, this domain may play an essential role in the introduction of a double bond into fatty acids bound to membrane lipids.
Amino Acid Sequence↗
Cloning of omega 3 desaturase from cyanobacteria and its use in altering the degree of membrane-lipid unsaturation.
Cyanobacteria respond to a decrease in temperature by desaturating fatty acids of membrane lipids to compensate for the decrease in membrane fluidity. Among various desaturation reactions in cyanobacteria, the desaturation of the omega 3 position of fatty acids is the most sensitive to the change in temperature. In the present study, we isolated a gene, designated desB, for the omega 3 desaturase from the cyanobacterium, Synechocystis sp. PCC 6803. The desB gene encodes a protein a 359 amino-acid residues with molecular mass of 41.9 kDa. The desB gene is transcribed as a monocistronic operon that produced a single transcript of 1.4 kb. The level of the desB transcript in cells grown at 22 degrees C was 10 times higher than that in cells grown at 34 degrees C. In order to manipulate the fatty-acid unsaturation of membrane lipids, the desB gene in Synechocystis sp. PCC 6803 was mutated by insertion of a kanamycin-resistance gene cartridge. The resultant mutant was unable to desaturate fatty acids at the omega 3 position. The desA gene, which encodes the delta 12 desaturase of Synechocystis sp. PCC 6803, and the desB gene were introduced into Synechococcus sp. PCC 7942. Whilst the parent cyanobacterium can only desaturate membrane lipids at the delta 9 position of fatty acids, the resultant transformant was able to desaturate fatty acids of membrane lipids at the delta 9, delta 12 and omega 3 positions. These results confirm the function of the desB gene and demonstrate that it is possible to genetically manipulate the fatty-acid unsaturation of membrane lipids in cyanobacteria.
Amino Acid Sequence↗
Transforming growth factor-beta regulates human retinal pigment epithelial cell phagocytosis by influencing a protein kinase C-dependent pathway.
BACKGROUND: Transforming growth factor-beta (TGF-beta) plays an important role in the pathogenesis of many ocular diseases, including proliferative vitreoretinopathy. We examined the effect of TGF-beta on the phagocytosis of rod outer segments by retinal pigment epithelium (RPE), which is a major function of RPE, and investigated the dependence of this effect on the protein kinase C (PKC) pathway. METHODS: Phagocytotic uptake of fluoresceinated bovine rod outer segments was determined by flow cytometry. RPE cells were treated with TGF-beta 1 or TGF-beta 2 and their effects on phagocytosis were examined. The effects of various PKC inhibitors (calphostin C, staurosporine, and extended exposure to phorbol 12-myristate 13-acetate, PMA) and a stimulator (brief exposure to PMA) on RPE phagocytosis was evaluated. RESULTS: Both TGF-beta 1 and TGF-beta 2 up-regulated RPE phagocytosis and PMA abolished the up-regulating effect of TGF-beta. In contrast, PKC inhibition by staurosporine and calphostin C resulted in increased phagocytosis. A combination of TGF-beta and PKC inhibitor treatment did not produced any additive effect on phagocytosis. CONCLUSION: We concluded that TGF-beta up-regulates human RPE phagocytosis, but that this effect is counteracted by PKC activation. It is possible that this TGF-beta-induced effect is due, in part, to a negative modulation of the PKC-dependent pathway.
Alkaloids↗