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Biomedical subjects

K Negishi

Publications and source records attributed to K Negishi.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Vena caval flow patterns in patients with constrictive pericarditis: analysis by catheter-tip Doppler flowmetry].

Changes in superior and inferior vena caval flow patterns were analyzed in 5 patients with constrictive pericarditis and were compared with those of 10 normal control subjects. Caval flows were measured using catheter-tip Doppler flowmeters. The normal controls showed biphasic M-shaped flow patterns; the peaks of the first forward flow (S wave) and of the second forward flow (D wave) appeared coincident with mid-systole and mid-diastole, respectively. Reverse flows fell during the atrial contraction period (A wave) and late systole (V wave). In the normal controls, the ratios of the S wave to the D wave (S/D ratio) and the A wave to the S wave (A/S ratio) were 2.15 +/- 0.41 and 0.18 +/- 0.10, respectively, and there was a disproportionate respiratory variation in the S and D waves in the normal controls. In constrictive pericarditis, superior and inferior vena caval flow velocities were lower than those in the normal controls. The S/D and A/S ratios were 1.46 +/- 0.27 (p < 0.05 vs control) and 0.66 +/- 0.15 (p < 0.01 vs control), respectively, with the A wave increasing in proportion to the severity of constrictive pericarditis. In addition, there was only a minimal respiratory variation in constrictive pericarditis. In conclusion, recognition of the patterns of the superior and inferior vena caval flow velocities may be useful for diagnosing constrictive pericarditis.

Adult↗
PubMed1991

Inhibition of DNA chain elongation by a phosphotriester linkage in template oligodeoxyribonucleotides.

We synthesized two oligodeoxyribonucleotides bearing an isopropyl phosphotriester at defined positions using new phosphorobisamidite chemistry. Diastereomers were separated with HPLC and their template properties were analyzed. Priming oligodeoxyribonucleotides labeled with 32P at the 5'-end were annealed to the modified oligodeoxyribonucleotides and elongated with DNA polymerase I large fragment from Escherichia coli. Results show that the phosphotriester inhibits the DNA chain elongation partially and the extents of the inhibition are remarkably different between the two diastereomers.

Base Sequence↗
PubMed1991

Permanganate oxidation of nucleic acid components: a reinvestigation.

KMnO4 consumption in solution by nucleoside added at an excess was measured to explore any possible oxidative interactions between these molecules. Thymidine, 5-methyldeoxycytidine and deoxycytidine rapidly decomposed KMnO4 with the pseudo-first-order kinetics (thymidine greater than 5-methyl-deoxycytidine greater than deoxycytidine), while deoxyguanosine showed only a very slow consumption and deoxyadenosine did not decompose KMnO4 at all under the conditions employed (0.16 mM KMnO4, 0.80 mM nucleoside, at 27 degrees C and pH 4.3, 7.4 and 8.6, up to 60 min). UV absorption spectra of KMnO4-treated nucleosides also indicated modification of the pyrimidine nucleosides but not of the purine nucleosides. These results are consistent with the original report of Hayatsu and Ukita published in 1967 on the KMnO4 oxidation of nucleosides, and provide difficulty in understanding the mechanism of recently reported formation of 8-hydroxypurines on treatment of DNA with KMnO4.

Manganese↗
PubMed1991

[Real-time coronary blood flow measurement in patients with atrial fibrillation: a study using a catheter-tip Doppler velocimeter].

To clarify the influence of changes in the cardiac cycle length (R-R) and aortic pressure on the coronary blood flow, a catheter-tip Doppler velocimeter was applied for 16 patients with chronic atrial fibrillation (11 with valvular heart disease, 2 with coronary artery disease, 2 with cardiomyopathy and one with atrial septal defect). An area under the coronary flow velocity curve during systole (integral of S), diastole (integral of D) and one cardiac cycle (integral of T) for the proximal portion of the left anterior descending artery (LAD: 12 cases) or the right coronary artery (RCA: 10 cases) was calculated in beat-by-beat. Then, the correlations between each area and the R-R, systolic period (S), diastolic period (D) and aortic pressure were assessed. In both the LAD and RCA, prolongation of R-R associated with prolonged D increased integral of D, which caused an increase of integral of T. Integral of D correlated with D (p < 0.05), but integral of S did not correlate with S, and the degree of change in integral of S or S was much less than that in integral of D or D. R-R or D of the preceding beat correlated inversely (p < 0.05) with integral S in 11 of 12 LAD cases. In the RCA, positive correlations between R-R or D of the preceding beat and integral of S were observed in cases with mitral stenosis (n = 6) or coronary heart disease (n = 1), but not in other cases; a case with aortic regurgitation or hypertrophic cardiomyopathy, negative, and dilated cardiomyopathy, no correlation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Early histogenesis of the teleostean retina: studies using a novel immunochemical marker, proliferating cell nuclear antigen (PCNA/cyclin).

Immunoreactive proliferating cell nuclear antigen or cyclin (ir-PCNA), detected by immunofluorescence using a human autoantibody, was used as a marker for proliferating neuroblasts during early development of the teleostean retina. In a killifish (Medaka) and a cyprinid (goldfish), ir-PCNA was present in all retinal cells at the monolayer stage (embryonic day 2 in Medaka, days 3-4 in goldfish). Subsequently ir-PCNA was lost, as neuroblasts became postmitotic in a centre-to-periphery and proximal-to-distal (ganglion cells first, photoreceptors last) sequence. In late larvae and adults, neuronal ir-PCNA was confined to the ring of proliferating neuroblasts at the retinal margin and scattered rod precursors in the outer nuclear layer. The changes in localization of ir-PCNA during development parallel closely the changes in localization of [3H]thymidine incorporation, reported previously.

Animals↗
PubMed1990

Emergence and development of immunoreactive cells in teleostean retinas during the perinatal period.

We have used light-microscopical immunohistochemistry to investigate developmental changes of several neurochemical indicators in retinas of perinatal killifish and goldfish. Immunoreactive proliferating cell nuclear antigen (ir-PCNA/cyclin, a marker for replicating cells) was present in nuclei of all neuroblasts in the early monolayer stage, but was lost progressively in central-to-peripheral and proximal-to-distal order as the layers and cells of the mature retina appeared. The loss of ir-PCNA was slightly prior to the appearance of ir-TH (tyrosine hydroxylase), GAD (glutamic acid decarboxylase) and GS (glutamine synthetase) at the 4th embryonic day (E4) in both fish. Since hatching was earlier in goldfish (E5) than in killifish (E7), neurochemical maturation was evident at 2-3 days before hatching in killifish but not until around hatching in goldfish. Two markers, ir-somatostatin and protein kinase C, were detected by the 1st postnatal day (H1) in goldfish, but not in perinatal or adult killifish retinas. Thus the course of development of killifish and goldfish retinas is similar, but not identical. The validity of ir-PCNA as a marker for proliferating cells is confirmed by the coincidence of its disappearance with the appearance of neurochemical markers for mature, postmitotic retinal cells.

Aging↗
PubMed1990

Close tip-to-tip contacts between dendrites of transient amacrine cells in carp retina.

In isolated retinas of the carp (Cyprinus carpio) placed receptor side up in a plastic chamber, a subclass of amacrine cells, generating a fast ON-OFF transient response to spot and annular light stimuli, were intracellularly recorded and injected with a fluorescent dye, Lucifer yellow (LY). After brief fixation of the same preparations in aldehyde solution, the retinas were wholemounted vitreous side up in a tissue chamber. Under a fluorescence microscope, one LY-injected cell and several dye-coupled cells were seen; these cells belonged to type Fnd, having a fusiform soma, narrow dendritic field and bistratified dentrites in the inner plexiform layer (IPL). To reveal the interconnections between dendrites, one of such dye-coupled cells was further injected with LY. Close tip-to-tip contacts were predominantly found between dendrites of neighboring type Fnd cells in sublaminae a and b of the IPL, respectively.

Animals↗
PubMed1990

2-(p-Nitrophenyl)-2'-deoxyadenosine, a new type of mutagenic nucleoside.

A crude preparation of 2-phenyladenosine was found to be mutagenic in the Ames Salmonella assay. In the purification of this preparation, it was revealed that 2-phenyladenosine itself was nonmutagenic but that 2-(m- and p-nitrophenyl)-adenosines (5m,p) contaminating the sample were the mutagenic principles. A structure-activity relationship study was carried out, and it was found that 5p, 2-(p-nitrophenyl)-adenine (7p), and 2-(p-nitrophenyl)-2'-deoxyadenosine (15p) were strongly mutagenic toward S. typhimurium TA98 and TA100 without metabolic activation, the potency being in the order 15p greater than 7p greater than 5p. The potency of 15p in TA98 was one order of magnitude greater than that of 4-nitroquinoline N-oxide. 15p also showed mutagenicity in the mouse cell line FM3A in culture.

Adenosine↗
PubMed1990

Sequential course of uptake of intravitreal 5,7-dihydroxytryptamine by carp retinal cells.

The sequential course of uptake by retinal cells of intravitreally injected 5,7-dihydroxytryptamine (5,7-DHT) together with dopamine (DA) was investigated in juvenile carp retinas, which were removed at various intervals (1-24 h) after injection. The cells taken up 5,7-DHT were visualized immunohistochemically with anti-serotonin (5-HT) antibody and FITC-conjugated IgG. After a mixture of 5,7-DHT and DA (2.5, 10 or 20 micrograms each) was given, large-sized indoleamine (IA) amacrine cells first (1-4 h), and then small-sized indoleamine-accumulating amacrine amacrine (IAA) cells (4-12 h), bipolar cells (8-12 h) and in some cases photoreceptor cells (12-24 h) were sequentially observed, and finally the immunoreactive structures almost disappeared around 24 h after injection. When the mixture of 5,7-DHT and DA (10 micrograms each) was injected into the eyes of reserpinized fish, the same sequential uptake of 5,7-DHT was seen in a faster time course, but additionally various classes of retinal cells (horizontal, ganglion and Müller cells) became visible as irregular clusters. However, DA cells were never visualized at any stages of all the experiments, indicating that DA cells do not take up 5,7-DHT in the carp retina, which was further confirmed by double labeling of 5-HT- and tyrosine hydroxylase-like immunoreactive cells. Double labeling also revealed that 5,7-DHT-accumulating bipolar cells appear to represent a subclass different from that of protein kinase C-like immunoreactive bipolar cells.

5,7-Dihydroxytryptamine↗
PubMed1990

Gliotoxic effects of alpha-aminoadipic acid isomers on the carp retina: a long term observation.

The glutamate analogue, alpha-aminoadipic acid was intravitreally administered in the D-, DL- and L-forms to carp (Cyprinus carpio) retina in vivo. To make a quantitative assessment of its gliotoxic action, the activity of glutamine synthetase, whose localization was confirmed in glial Müller cells by an immunohistochemical technique, was examined at various intervals over one month. Intravitreal injection of 8 mumol alpha-aminoadipic acids reduced the glutamine synthetase activity within 4 h and maximally by 24 h. The maximum reduction evoked by L-, DL- and D-forms was about 65, 45 and 28% in reduction, and their minimum effective dose was 0.8, 1.5 and 2.0 mumol, respectively. At three to four days after alpha-aminoadipic acids injection, sodium dodecyl sulphate gel electrophoresis suggested that some retinal proteins including glutamine synthetase were significantly reduced, whilst others were increased. These biochemical changes were fully reversed one to two weeks after administration of the D- or DL-forms, but not until one month with the L-form. The electroretinographic b-wave, reflecting glial activity, was completely blocked by 8 mumol alpha-aminoadipic acids within 4 h. The electroretinographic b-wave was recovered first in the case of D- and then of DL-form at two to three weeks after injection, but only 50% recovery was seen in the case of L-form even two months later. A high dose of DL-alpha-aminoadipic acid (16 mumol) induced as long lasting a suppression in the glutamine synthetase and electroretinographic b-wave activities as 8 mumol L-alpha-aminoadipic acid. Therefore, the gliotoxic efficacy of L-alpha-aminoadipic acid at micromol orders was two-fold higher than that of DL-alpha-aminoadipic acid. Differences in the time-course of recovery of the suppression of glutamate synthetase and electroretinographic b-wave activities induced by alpha-aminoadipic acids are discussed in terms of its gliotoxicity.

2-Aminoadipic Acid↗
PubMed1990

Neurotoxic effects of L-alpha-aminoadipic acid on the carp retina: a long term observation.

The hypothesis has been tested that the enantiomers of alpha-aminoadipic acid have different target effects; the L-isomer has both glio- and neurotoxic actions, while the DL-isomer has a gliospecific action in the CNS. Electrophysiological and morphological studies were carried out on the retina of the carp (Cyprinus carpio) for one to two months after intraocular injection with alpha-aminoadipic acids at various doses. Intracellular recording from horizontal cells and extracellular recording of spike discharges from ganglion cells in isolated retinal preparations were made from control and pretreated retinas at various intervals after intraocular injection with the enantiomers. In control retinas, application of 15 mM L-alpha-aminoadipic acid in the superfusate resulted in hyperpolarization of all horizontal cells and in a decrease in amplitude of their light responses (S-potentials). In the retinas pretreated with L-alpha-aminoadipic acid (8 mumol), low amplitude S-potentials were seen during an early phase 2-4 h after ocular injection, but the normal appearance of S-potentials was restored one day after injection. In control retinas, a brief period of iontophoretic application of L-alpha-aminoadipic acid resulted in a slight activation of the spontaneous spike firing of ganglion cells but a slight decrease in the rate of light-induced firing. In retinas pretreated with intraocular L-alpha-aminoadipic acid (4 mumol) 4 h prior to eye removal, however, light-induced spike discharges were abolished from nearly all spontaneously firing ganglion cells (greater than 90%). Their unresponsiveness to light stimuli lasted for more than two months after injection, and was accompanied by insensitivity to iontophoretically applied putative neurotransmitters.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Aminoadipic Acid↗
PubMed1990

Dopamine release via protein kinase C activation in the fish retina.

Calcium-dependent phospholipid-sensitive protein kinase [protein kinase C (PKC)] was partially purified from the carp (Cyprinus carpio) retina through DE 52 ion exchange and Cellulofine gel filtration chromatography. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) activated PKC in the nanomolar range. A major 38-kDa protein in the retinal supernatants (105,000 g) was phosphorylated in vitro by PKC during a short period (3 min). Other phosphoproteins also appeared during a further prolonged period (greater than 15 min). Rod-bipolar and dopamine (DA) interplexiform cells in the fish retina were immunoreactive to a monoclonal antibody to PKC (alpha/beta-subtype). The PKC antibody recognized a 78-kDa native PKC enzyme by means of an immunoblotting method. Subsequently, the effects of two kinds of PKC activators were investigated on [3H]DA release from retinal cell fractions containing DA cells that had been preloaded with [3H]DA. A phorbol ester (TPA) induced a calcium- and dose-dependent [3H]DA release during a short period (2 min), with the minimal effective dose being approximately 1 nM. Other phorbols having no tumor-promoting activity, such as 4 beta-phorbol and 4 alpha-phorbol 12,13-didecanoate, were ineffective on [3H]DA release. A synthetic diacylglycerol [1-oleoyl-2-acetylglycerol (OAG)], which is an endogenous PKC activator, was also able to induce a significant release of [3H]DA. Furthermore, TPA was found to release endogenous DA from isolated fish retina by a highly sensitive HPLC with electrochemical detection method. The OAG- or TPA-induced [3H]DA or DA release was completely blocked by inhibitors of PKC, such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) and staurosporine.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1990

[Molecular mechanism of N4-aminocytidine mutagenesis].

N4-Aminocytidine is strongly mutagenic towards E. coli, S. typhimurium, B. subtilis and coliphages phi X174 and M13mp2. It also causes mutations in mammalian cell lines and somatic cell mutations in D. melanogaster. The sequence analysis of deoxyribonucleic acid (DNA) from mutated phages revealed that N4-aminocytidine induces both adenine-thymine (AT) to guanine-cytosine (GC) and GC to AT transitions. No transversions are detectable. When E. coli and the mammalian cells were cultured in the presence of [3H]-N4-aminocytidine, [3H]-N4-aminodeoxycytidine was found in their DNA. It is likely that N4-aminocytidine is metabolized within the cells into N4-aminodeoxy-cytidine 5'-triphosphate (dCamTP), which is then incorporated into DNA, thereby causing base-pair transitions. To prove this hypothesis, we studied the incorporation of dCamTP into polynucleotides in the in vitro DNA synthesis catalyzed by E. coli DNA polymerase I large fragment (Klenow enzyme) and DNA polymerase alpha from a mouse cell line. Both polymerases catalyze incorporation of dCamTP into DNA efficiently in place of dCTP opposite guanine, and less efficiently, but to a significant extent, in place of dTTP opposite adenine. These observations prove the erroneous nature of dCamTP as a substrate for DNA synthesis. DNA containing N4-aminocytosine was prepared by the incorporation of dCamTP into single-stranded phage DNA annealed to complementary oligonucleotides. The DNA was transfected to E. coli cells. The analysis of progeny phages indicates that N4-aminocytosine residue in DNA causes A to G or G to A mutation in the position opposite to the site where N4-aminocytosine should be incorporated.

Animals↗
PubMed1990

Probing salt-induced and supercoiling-induced B-Z junctions in DNA by bisulfitemethoxyamine.

Salt-induced and supercoiling-induced B-Z junctions in pWR756, a plasmid containing (GC)16, were probed with bisulfite-methoxyamine, a modification reagent specific for single-stranded nucleic acids. The modification sites were analyzed with S1 nuclease and the modified cytosines were determined from termination sites of DNA chain elongation by DNA polymerase. The results showed that most accessible cytosines are the same for both types of B-Z junctions.

DNA, Single-Stranded↗
PubMed1990

MHC class II molecules (Ia-antigens) on macrophages in BB/W rats.

The percentage, absolute number and expression of Ia-antigen of macrophages (Mø) in peripheral blood cells (PBC) and splenocytes from Bio-Breeding/Worcester (BB/W) rats were evaluated. The percentage of Mø in PBC and splenocytes from BB/W rats was significantly higher than those in normal Wistar rats from Clea Japan Inc. (NW/C) and Charles River Japan Inc. (NW/CR). The percentage of Ia-positive Mø in PBC and splenocytes from BB/W rats was significantly increased compared with that in NW/C rats. On the other hand, there was no significant difference in the percentage of Ia-positive Mø of PBC between BB/W and NW/CR rats, and the percentage of Ia-positive Mø in the spleen from BB/W rats was significantly lower than those in NW/CR rats. Thus, the quantity of MHC class II molecules on circulating Mø is not related to the pathogenesis of diabetes mellitus in BB/W rats.

Animals↗
PubMed1989

A new hypoglycemic agent, midaglizole, blunts diabetic platelet aggregation: a possible role of alpha 2 blockade.

A newly developed alpha 2 blocker, midaglizole (DG-5128, 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylethyl] pyridine dihydrochloride sesquihydrate) has been shown to have a hypoglycemic action in healthy controls as well as in diabetics. Since human platelets are rich in alpha 2 receptors, the effects of midaglizole on platelet aggregation were investigated. In normal controls, ADP- or epinephrine-induced platelet aggregation was significantly inhibited 2 h after oral administration of 300 mg midaglizole. Midaglizole also suppressed diabetic platelet aggregation stimulated by 10 or 100 microM epinephrine and delayed the initiation of collagen-induced aggregation at 30 micrograms/ml. In vitro addition of midaglizole at 9 or 90 microM significantly inhibited epinephrine-induced platelet aggregation. Furthermore, long-term administration of midaglizole suppressed diabetic platelet aggregation induced by 0.5-1 microM ADP or 1 microM epinephrine. These results suggest that alpha 2 blockade not only blunts diabetic epinephrine-induced platelet aggregation but also affects ADP- or collagen-stimulated platelet aggregation, indicating that this alpha 2 blocker may offer a new approach to the treatment of diabetic microangiopathy.

Adrenergic alpha-Antagonists↗
PubMed1989

Dendritic morphology of retinal dopamine cells in carp of different sizes.

The dendritic morphology of dopamine (DA) cells in the inner plexiform layer of the retina of different-sized carp (8.6-33.6 cm in body length) was investigated by identifying their fluorescent cell bodies in isolated, aldehyde-fixed flatmounts and injecting them iontophoretically with Lucifer yellow (LY) under microscopic control. DA cells for LY injection were chosen in an intermediate region between the optic disc and the retinal margin, and their spatial parameters (cell density, nearest neighbor distance, dendritic field size and dendritic coverage) were compared between retinas of different sizes to explore whether this region is simply stretched by tissue expansion during retinal growth. It was shown that as the fish grow larger the dendritic field size of DA cells increases while the cell density is sharply reduced and the dendritic coverage gradually decreases. Differences in the dendritic coverage of DA cells between certain fish groups with different sizes were statistically significant. Further, the irregularity in cell distribution appeared to increase as the fish became larger. These results suggest that the dendritic tree of individual DA cells in the intermediate region is developed not only by tissue expansion but also by other unknown factors.

Animals↗