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Biomedical subjects

N Ogata

Publications and source records attributed to N Ogata.

At least 127 records · Page 7Linked to original sources
PubMed1996

[Usefulness of contrast-enhanced CT of the peritoneum to evaluate efficacy of neoadjuvant chemotherapy for peritoneal dissemination in an advanced gastric cancer case].

We performed contrast-enhanced CT before and after chemotherapy in a patient with advanced gastric cancer to assess the efficacy of neoadjuvant chemotherapy for peritoneal dissemination. The patient was preoperatively given combined chemotherapy with UFT and CDDP. Hepatic metastatic and peritoneal disseminated foci were markedly reduced on CT. Thus CT proved to be useful for assessing peritoneal dissemination and the efficacy of neoadjuvant chemotherapy.

Aged↗
PubMed1996

FGF receptor 1 expression in experimental choroidal neovascularization.

Fibroblast growth factor (FGF) is an important factor in neovascularization. To clarify the role of FGF, we demonstrated the expression of FGF receptor 1 mRNA in experimentally induced choroidal neovascularization using in situ hybridization. Krypton laser photocoagulation was applied to the posterior retina of colored rats to induce choroidal neovascularization; the eyes were removed at various intervals after photocoagulation. Chorioretinal sections were made, and FGF receptor 1 cDNA fragments were used to make antisense and sense probes for in situ hybridization. In normal chorioretinal tissue, stain indicating FGF receptor 1 mRNA was observed in the ganglion cells and the inner nuclear layer. After photocoagulation, FGF receptor 1 mRNA appeared in the retinal pigment epithelial cells, in melanocytes of the choroid and in the choroidal blood vessel wall of the photocoagulation lesions. This suggests that FGF is involved in the process of neovascularization. Previous studies have reported that the capillary endothelial cells and retinal pigment epithelial cells produce basic FGF in vitro; FGF may affect the cells in an autocrine or paracrine manner.

Animals↗
PubMed1996

Gene expressions of basic fibroblast growth factor and its receptor in healing of rat retina after laser photocoagulation.

Basic fibroblast growth factor (bFGF) stimulates the mitogenesis of various cells and plays a key role in wound repair. Using in situ hybridization, we studied mRNA expressions of bFGF and one of its receptors, FGF receptor 1 (FGFR1), during wound repair of the rat retina after laser photocoagulation. Gene expressions of bFGF and FGFR1 were detected in the ganglion cell and inner nuclear layers of the normal adult rat retina. On day 3 following laser photocoagulation, proliferating retinal pigment epithelial (RPE) cells of the lesion showed intense gene expressions of bFGF and FGFR1. Macrophage-like cells that migrated into the lesion also showed gene expression of bFGF. These gene expressions decreased over time. The finding of elevated gene expressions of bFGF and FGFR1 after laser photocoagulation suggests the bFGF may be a factor in retinal wound repair.

Animals↗
PubMed1995

Long-term repopulation of hematolymphoid cells with only a few hemopoietic stem cells in mice.

A PCR-based assay has been devised for the detection and semiquantitation of cells originating from a few donor hematopoietic stem cells (HSCs) in a background of recipient cells. Upon sequencing a segment of murine Y chromosome contained in the plasmid pY2, oligonucleotide primers were designed for specific amplification of the Y chromosome-restricted segment. The HSCs were isolated from the bone marrow of mice on day 4 following a single i.v. injection of 5-fluorouracil and were readily distinguished from other bone marrow elements by the characteristics of low density, absence of lineage-specific surface markers, lack of expression of transferrin receptor, and a high expression of major histocompatibility complex class I antigen. Injection of as few as four such HSCs was shown to produce donor-derived cells (including lymphoid cells) for at least 8 months after transplantation into syngeneic female recipients. Retransplantation, employing 10(6) bone marrow cells from the initial recipients, also yielded clear evidence of repopulation with detectable levels of male donor cells. On statistical grounds, it is clear that long-term repopulation in vivo may result from even a single HSC having the characteristics defined herein.

Animals↗
PubMed1995

[Current treatment concepts in patients in the acute stage of subarachnoid hemorrhage due to rupture of an intracranial aneurysm].

Subarachnoid hemorrhage (SAH) due to rupture of intracranial aneurysm constitutes almost 10% of all strokes and is a neurosurgical emergency along with head injury and intracerebral hemorrhage. Accurate diagnosis and surgical intervention without time loss are the key factors for successful treatment. Almost 40% of the patients with SAH already die or are in a moribund status at the first bleeding before hospitalization, the rest of the patients (60%) can be transferred to hospitals for further treatment. The factors determining prognosis of SAH involve a direct initial injury to the brain at the time of the rupture, a high rebleeding rate in the acute stage, development of cerebral vasospasms, and hydrocephalus due to stasis of the cerebrospinal fluid. Surgical intervention is intended to eliminate these factors as much as possible. Perioperative intensive medical care in combination with the surgical intervention is essential to achieve best outcome from the surgical treatment. The aim of this article is to make a short review over SAH and to give a current concept of therapy in the acute stage of SAH. The results of treatment of SAH in our institute are also presented and discussed.

Cerebral Angiography↗
PubMed1995

Single-channel analysis of two types of Na+ currents in rat dorsal root ganglia.

The properties of voltage-gated Na+ channels were studied in neurones isolated from rat dorsal root ganglia using the outside-out configuration of the patch-clamp technique. Two types of single-channel currents were identified from the difference in unit amplitudes. Neither type was evoked in the medium in which extracellular Na+ ions were replaced by an equimolar amount of tetramethylammonium ions. The two types of single-channel currents differed in their sensitivity to tetrodotoxin (TTX). The smaller channel current was insensitive to 1 microM TTX (referred to as TTX-I), while the larger channel current was blocked by 1 nM TTX (TTX-S). The unit amplitudes measured during a step depolarization to -30 mV (1.4 mM internal and 250 mM external Na+ concentrations) were 1.16 pA for TTX-S and 0.57 pA for TTX-I, respectively. The slope conductance measured at -30 mV was 16.3 pS for TTX-S and 8.5 pS for TTX-I. TTX-S could be activated by step depolarizations positive to -60 mV, while TTX-I could be activated at potentials positive to -40 mV. When the test pulse was preceded by a depolarizing prepulse, the prepulse positive to -50 mV preferentially inactivated TTX-S with a minimal effect on TTX-I. Activation and inactivation time courses of the averaged ensemble currents computed from TTX-S showed remarkable resemblances to the time courses of the macroscopic TTX-sensitive Na+ current. Similarly, the ensemble currents of TTX-I mimicked the macroscopic TTX-insensitive Na+ current. It was concluded that the two types of Na+ channels in rat dorsal root ganglia differ not only in their sensitivity to TTX, but also in their single-channel conductances.

Animals↗
PubMed1995

Temperature-modulated platelet and lymphocyte interactions with poly(N-isopropylacrylamide)-grafted surfaces.

Temperature-responsive semitelechelic poly(N-isopropylacrylamide) (PIPAAm) bearing a carboxyl end group has been chemically immobilized on aminated polystyrene particle surfaces via condensation reaction. PIPAAm-grafted particles were uniformly suspended in aqueous media at lower temperatures. With increasing temperature, PIPAAm-grafted particles aggregated and precipitated. Such reversible changes in particle colloidal behaviour was correlated to temperature-modulated hydrophilic/hydrophobic changes of particle surfaces modified by PIPAAm hydration/dehydration with temperature changes. Interactions between platelets and PIPAAm-grafted surfaces were studied by monitoring cytoplasmic free Ca2+ concentration ([Ca2+]i) changes in platelets using intracellularly-trapped Ca2+ indicator dye, Fura 2, at various temperatures. Although changes in [Ca2+]i in platelets in contact with PIPAAm-grafted particles were not observed below the critical temperature of PIPAAm, significant changes in [Ca2+]i in platelets were induced by contact with particles above this critical temperature. Furthermore, temperature-modulated cell adsorption/desorption control by PIPAAm-grafted particles was investigated using a particle aggregation assay in the presence of lymphocytes. Below the critical temperature of PIPAAm, mixed suspensions were completely homogeneous due to minimal interaction between lymphocytes and hydrated particles. In contrast, aggregated precipitates were observed by increasing the suspension temperature above the critical temperature of PIPAAm resulting from strong hydrophobic interactions between particles with lymphocytes. These precipitates are reversibly resuspended in cold buffer. The feasibility of cell activation/inactivation or cell attachment/detachment control by temperature-modulated surface changes is attractive for suspension cell culture and drug delivery at targeted sites in vivo.

Acrylic Resins↗
PubMed1995

Prolonged hyperalimentation as a possible cause of renal tubular dysfunction: evaluation of 1,5-anhydro-D-glucitol resorption and N-acetylglucosaminidase excretion in humans.

1. A major polyol found in the sera and other tissues of humans, 1,5-anhydro-D-glucitol, is mainly ingested in the diet and is excreted in urine. We compared the influence of the long-term administration of total parenteral nutrition free of 1,5-anhydro-D-glucitol with that of total enteral nutrition on the serum level of 1,5-anhydro-D-glucitol in 46 patients who could not take food by mouth. 2. The serum concentration of 1,5-anhydro-D-glucitol and its kinetics remained unchanged in the group receiving total enteral nutrition (n = 21) over a period of 12 months. However, after 1 month on total parenteral nutrition (n = 25), the serum level of 1,5-anhydro-D-glucitol decreased, falling to about one-sixth the pretreatment level in the 12th month. Because the serum level of 1,5-anhydro-D-glucitol continued to decline, falling below the limit at which its renal reabsorption is normally activated, this decrease did not seem to be caused directly by a nutritional deficiency of this substance. 3. The urinary excretion of 1,5-anhydro-D-glucitol was closely correlated (r = 0.792) with that of N-acetyl-beta-glucosaminidase; but not with the serum creatinine level or of the urinary excretion of microalbumin or of urinary beta 2-microglobulin. We observed no glucosuria, hyperuricuria or changes in serum electrolytes during total parenteral nutrition. 4. The reduction in the serum level of 1,5-anhydro-D-glucitol and the urinary excretion of N-acetyl-beta-glucosaminidase were correlated with the duration of total parenteral nutrition administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1995

Pharmacokinetics of wood creosote: glucuronic acid and sulfate conjugation of phenolic compounds.

Wood creosote, principally a mixture of non-, alkyl- and/or alkoxy-substituted phenolic compounds, was orally administered to adult male volunteers to determine its metabolites and pharmacokinetic parameters. After a 133-mg single dose, its major constituents (i.e. phenol 15 mg, guaiacol 32 mg, p-cresol 18 mg and creosol 24 mg) were found in peripheral venous blood and urine, mostly as glucuronic acid and, except for creosol, as sulfate conjugates. Low concentrations of unconjugated phenols were also detected. The metabolites in the serum started to increase 15 min after the dose, and they reached their maximum concentrations 30 min after administration. The maximum concentrations of glucuronides were 0.18 +/- 0.07, 0.91 +/- 0.38, 0.33 +/- 0.18 and 0.47 +/- 0.23 mg/l; those of sulfates were 0.16 +/- 0.06, 0.22 +/- 0.09, 0.17 +/- 0.07 and < 0.04 mg/l for phenol, guaiacol, p-cresol and creosol, respectively. The 24-hour urinary recoveries of the sum of each compound and its metabolites were 75 +/- 35, 45 +/- 36, 103 +/- 51 and 74 +/- 36%, in the above order. The presence of guaiacol glucuronide in blood and urine was directly verified by its isolation and structure analyses.

Adult↗
PubMed1995

Effect of MPL 9000 extracorporeal shock wave lithotripsy on renal hemodynamics and urine flow: assessment by 99mTc-DTPA renal scintigraphy.

The effect of extracorporeal shock wave lithotripsy (ESWL) with an MPL9000 lithotriptor on renal hemodynamics and urine flow was investigated by 99mTc-DTPA renal scintigraphy. In the first-pass scintigrams obtained within 1 min after injection of 99mTc-DTPA, there was no significant change in the time to the maximum radioactivity level and the maximum radioactivity ratio at 1 day before ESWL and 1 day or 1 month after ESWL. However, analysis of 30-min scintigrams showed that urinary clearance of radioactivity was delayed in the treated kidney 1 day after ESWL, particularly in the region targeted by shock waves, despite the absence of overt urinary tract obstruction by residual stone fragments. This change was reversible and was no longer noted 1 month after ESWL. These results suggest that ESWL with the MPL9000 lithotriptor induces a focal and temporary decrease in urine flow in the treated kidney, but has little or no effect on renal hemodynamics.

Adult↗
PubMed1995

Endothelial cell differentiation into capillary structures by copolymer surfaces with phenylboronic acid groups.

A ternary copolymer composed of m-acrylamidophenylboronic acid, N,N-dimethylaminopropylmethacrylamide and N-isopropylacrylamide was synthesized. Long-term culture of bovine aortic endothelial cells on this copolymer substrate demonstrated adhesion and proliferation of the cells. After 26 days in culture, endothelial cells spontaneously developed into capillary networks. The interactions between phenylboronic acid groups in copolymer and glycoconjugates on endothelial cell plasma membranes are proposed to regulate the induction of tissue formation, since phenylboronic acid groups are known to specifically form reversible complexes with cis-diol compounds such as glucose. This copolymer is a novel material capable of mediating specific signals analogous to extracellular matrix to promote proliferation of endothelial cells, inducing capillary structures and prompt angiogenesis.

Acrylamides↗
PubMed1995

[Expression of fibroblast growth factor receptor 1 in experimental choroidal neovascularization with in situ hybridization].

Fibroblast growth factor (FGF) is an important factor for neovascularization in vivo. In order to clarify the role of FGF in experimentally produced choroidal neovascularization, we demonstrated mRNA for FGF receptor 1 in situ hybridization. Krypton laser photocoagulation was applied to the posterior retina of colored rats to produce choroidal neovascularization experimentally. These eyes were removed at several different intervals after photocoagulation. Chorioretinal section were used for in situ hybridization. FGF receptor 1 cDNA fragment was used to make antisense and sense probes for in situ hybridization. In normal chorioretinal tissue, staining indicating the existence of FGF receptor 1 mRNA was seen in the ganglion cell layer and inner nuclear layer. After the photocoagulation, the staining was seen in the retinal pigment epithelial cells, melanocytes in the choroid, and choroidal blood vessel wall in the photocoagulated lesions. FGF receptor 1 mRNA was expressed through the development of choroidal neovascularization, and it appears that FGF is necessary for development of choroidal neovascularization. Previous workers showed that the capillary endothelial cells and retinal pigment epithelial cells produce basic FGF in vitro. It seems that FGF effects those cells in an autocrine or paracrine manner in vivo.

Animals↗
PubMed1994

Effect of nerve growth factor on delayed neuronal death after cerebral ischaemia.

We investigated the protective action of nerve growth factor (NGF) on delayed neuronal death, and we also studied the involvement of the 200 kDa neurofilament (NF200) cytoskeletal proteins. Wistar rats were divided into three groups: Group I, in which transient forebrain ischaemia was produced; Group II, ischaemic group which received intraventricular administration of artificial cerebrospinal fluid (CSF); and Group III, ischaemic group which received intraventricular administration of 2 micrograms of 2.5 S NGF. Forebrain ischaemia in these rats was produced by causing transient bilateral occlusion of the common carotid arteries and lowering the mean blood pressure to 50 mmHg for 8 minutes. On the 1st and 7th day after ischaemia we histologically examined neuronal death in the hippocampal CA 1 sector. On the 7th day after ischaemia, mean cell death (degenerative cell number/total cell number) was 87 +/- 9% in group I (n = 7), 51 +/- 36% in group II (n = 7), and 14 +/- 16% in group III (n = 8) (p < 0.05 vs. group II). The concentration of NF200 in the hippocampal homogenate was measured by the Western blotting method on the 1st and 7th day after ischaemia. On the 1st day it was found to be 67 +/- 11% of that in the control group in group I (n = 6), 73 +/- 21% in group II (n = 6), and 84 +/- 7% in group III (n = 6) (p < 0.05 vs. group II). The concentration of NF200 in all groups remained at the same level until the 7th day after ischaemia (each group, n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Clinical significance of urinary enzymes and beta 2-microglobulin following ESWL.

To examine the renal damage caused by shock waves, urinary excretion of enzymes and beta 2-microglobulin were determined before and after ESWL. Urine samples were obtained from 35 patients with renal stone and 26 patients with ureteric stone treated with ESWL. Urinary lactate dehydrogenase (LDH) levels significantly increased on day 0, just after ESWL, in both groups. In the ureteric stone group the kidneys received less shock waves than in the renal stone group. Increased urinary lactate dehydrogenase was considered to have derived from erythrocytes in urine. Elevated urinary N-acetyl-beta-D-glucosaminidase (NAG) levels were also observed on day 0 after ESWL in both groups, due to unknown reasons. Indirect effect of ESWL through the sympathetic nervous system or humoral factors may contribute to increases in the urinary excretion of NAG. No significant increase was found in urinary gamma-glutamyl-transpeptidase (GGTP) levels for 5 days after ESWL. Urinary beta 2-microglobulin (BMG) levels increased on day 0 in the renal stone group alone. In our present study, the clinical significance of urinary enzymes and BMG was not well evaluated, because urinary excretion of these indicators following ESWL were transient and mild.

Acetylglucosaminidase↗
PubMed1994

Temperature modulated solubility-activity alterations for poly(N-isopropylacrylamide)-lipase conjugates.

Chemical modification of proteins by use of functional polymers is expected to endow them with new properties without destroying their native functions, thus providing useful materials for application in different fields. We have synthesized poly(N-isopropylacrylamide) [poly(IPAAm)] co-oligomer with N,N-dimethylacrylamide (DMAAm) and reactive end groups by telomerization of IPAAm. This co-oligomer exhibits a lower critical solution temperature (LCST) at 37 degrees C. Using this temperature-responsive semitelechelic co-oligomer, we prepared polymer-enzyme conjugates of lipase by covalent coupling via carboxyl end-groups. This bioconjugate exhibits a LCST at 37 degrees C, having rapid, reversible hydration-dehydration changes due to highly mobile free polymer end groups. The conjugate retained its native enzymatic activity below this critical temperature, above which it precipitated and its catalytic function was shut off. This conjugate can be readily separated from reaction mixtures as a precipitate by simple temperature changes after reaction and reused in cycles without denaturation. Such a modulated system is attractive for application as a novel bioreactor system.

Acrylic Resins↗