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Biomedical subjects

Y Takehara

Publications and source records attributed to Y Takehara.

At least 73 records · Page 4Linked to original sources
PubMed1995

Inhibition of stimulus-specific neutrophil superoxide generation by alpha-tocopherol.

Alpha-tocopherol but not 2-carboxy-2,5,7,8-tetramethyl-6-chromanol (trolox or CTMC) and 2,2,5,7,8 pentamethyl-6-hydroxy chromane (PMC), derivatives of alpha-tocopherol, inhibited the superoxide (O2-.) generation of rat peritoneal neutrophils (RPMN) induced by phorbol 12-myrisate 13-acetate (PMA). ID50 for neutrophils obtained from the peritoneal cavity of rat and guinea pig was about 1microM. This concentration, however, was much lower than that for the inhibition of PMA-activated phospholipid-dependent protein kinase (PKC) (ID50 = 30 microM). The alpha-tocopherol sensitive O2-. generation was also observed in neutrophils induced by dioctanoylglycerol (diC8) and calcium ionophore A23187 but not by formylmethionyl-leucyl-phenylalanine (FMLP), opsonized zymosan (OZ) and sodium dodecyl sulfate (SDS). The pattern of inhibition by alpha-tocopherol was quite similar to that of staurosporine, a specific inhibitor of PKC. The alpha-tocopherol content of RPMN was 12 ng/10(6) cells and a linear increase to 200 ng/10(6) cells by addition of alpha-tocopherol to the cell suspension corresponded with an increased inhibition of O2-. generation. These results indicate that both the chemical structure and the content of alpha-tocopherol might be important factors in O2-. generation by neutrophils.

Animals↗
PubMed1995

[Enhanced delineation of the pancreatic duct in MR cholangiopancreatography (MRCP) with a combined use of secretin].

Magnetic resonance cholangiopancreatography (MRCP) is a method that can depict the main pancreatic duct non-invasively; however, its tendency to overestimate ductal stenosis is being noted. The authors used secretin to stimulate the output of pancreatic juice, which increased the signal of the main pancreatic duct and consequently minimized the occurrence of pseudostenosis artifacts in MRCP. MRCP images of 54 patients suspected of having pancreatic disease were visually evaluated by two observers before and after administration of secretin (1 clinical unit/kg). Improved delineation of the main pancreatic duct (68.5-59.3%, p < 0.05) and its side branches (40.7-29.6%, p < 0.05) was obtained with good interobserver agreement (kappa = 0.71-0.68).

Aged↗
PubMed1995

Protection against alloxan diabetes by low-dose 60Co gamma irradiation before alloxan administration.

We evaluated the protective effects of a single low-dose whole body 60Co gamma irradiation against alloxan-induced hyperglycemia in rats. i) In rats that did not receive alloxan, the superoxide dismutase (SOD) activity in the pancreas significantly increased after irradiation at a dose of 0.5 or 1.0 Gy. ii) In rats that received alloxan, plasma lipid peroxide levels, pancreatic lipid peroxide levels and blood glucose were increased. However, the increase in pancreatic lipid peroxide level was prevented by irradiation at a dose of 0.5 or 1.0 Gy; and the increase in blood glucose, by irradiation at 0.5 Gy. iii) After alloxan administration, degranulation was observed in beta cells, but this was prevented by low-dose irradiation at 0.5 Gy.

Animals↗
PubMed1994

Breath-hold MR cholangiopancreatography with a long-echo-train fast spin-echo sequence and a surface coil in chronic pancreatitis.

PURPOSE: To assess heavily T2-weighted breath-hold magnetic resonance cholangiopancreatography (MRCP) for imaging the pancreatic duct in patients with chronic pancreatitis. MATERIALS AND METHODS: Thirty-nine patients with chronic pancreatitis were examined with a breath-hold fast spin-echo (FSE) sequence employing an echo train length of 32 and with a surface coil. Results were compared with those of endoscopic retrograde cholangiopancreatography (ERCP). RESULTS: MRCP showed the head, body, and tail of the pancreatic duct well in 79%, 64%, and 53% of cases, respectively. Agreement between MRCP and ERCP was 83%-92% in cases of ductal dilatation, 70%-92% in cases of ductal narrowing, and 92%-100% in cases of filling defects. Interobserver variation was low (kappa > 0.5) for most findings. CONCLUSION: Breath-hold MRCP with an FSE technique depicts the pancreatic duct well in patients with chronic pancreatitis and demonstrates narrowing, dilatation, and filling defects with moderate to high accuracy.

Aged↗
PubMed1994

Effect of interleukin-1 beta on ovulation in the in vitro perfused rabbit ovary.

Interleukin-1 (IL-1), a prominent 17-kilodalton member of a group of immune mediators referred to as cytokines, is secreted by a variety of immuno- and nonimmunocompetent cells. As IL-1 is an established mediator of inflammation, and ovulation may constitute an inflammatory-like reaction, consideration may be given to the possibility that IL-1 may play an intermediary role in the ovulatory process. Such a hypothesis is supported by the recent demonstration of the gonadotropin-dependent preovulatory induction of IL-1 transcripts at the level of the murine and human ovary. To date, however, the direct effect of IL-1 beta on the ovulatory process has not been examined. The objective of this study was to investigate the potential role of IL-1 beta in ovulation, oocyte maturation (nuclear and cytoplasmic), and subsequent fertilizability of in vitro ovulated oocytes. Rabbit ovaries perfused in vitro were used for these experiments. Ovarian arteries were cannulated in situ, and the ovaries were excised and perfused in vitro with or without IL-1 beta (18 ng/ml). The ovulatory efficiency of 18 ng/ml IL-1 beta-treated ovaries was 73.1%, similar to that of hCG (71.2%). Recovered oocytes were examined for their maturation and were inseminated in vitro to investigate fertilization, cleavage, and embryonic development. The fertilization rates of the 18 ng/ml IL-1 beta-treated and hCG-treated groups were 65.8% and 95.8% (P < 0.01), respectively. Cleavage rates of the IL-1 beta-treated and hCG-treated groups were 50% and 83.3% (P < 0.01), respectively. Most of the cleaved embryos from the IL-1 beta-treated group arrested at the four-cell stage, and only 2.6% of the fertilized embryos developed into the morula stage, whereas 54.2% of the hCG-treated group developed to the morula stage (P < 0.01). A cytotoxic effect of IL-1 beta is unlikely in this model. A more likely explanation is the induction of other factors by IL-1 beta, which may inhibit cytoplasmic maturation. Taken together, our findings demonstrate that in the absence of an ovulatory gonadotropic trigger, IL-1 beta can induce ovulation and oocyte maturation, facilitate fertilization, and influence subsequent embryonic development. Although fertilization and embryonic development occurred after IL-1 beta treatment, these rates were lower than those after hCG treatment. These observations give credence to the possibility that IL-1 may play an intermediary role in the ovulatory process.

Animals↗
PubMed1994

Occlusion of the posterior humeral circumflex artery: detection with MR angiography in healthy volunteers and in a patient with quadrilateral space syndrome.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of MR angiography in detecting occlusion of the posterior humeral circumflex artery and to determine if the finding is specific for the diagnosis of quadrilateral space syndrome. SUBJECTS AND METHODS: Two-dimensional fast low-angle shot MR angiography was used to image both shoulders of one symptomatic patient and six asymptomatic volunteers (10 posterior humeral circumflex arteries). RESULTS: With the arm in a neutral position, the posterior humeral circumflex arteries appeared normal on MR angiograms of all subjects. However, when the arm was in abduction, occlusion of the posterior humeral circumflex artery was seen both in the symptomatic patient and in 80% of the asymptomatic volunteers. CONCLUSION: Our data show that occlusion of the posterior humeral circumflex artery is common in asymptomatic volunteers. Thus, MR angiography has no value in the diagnosis of quadrilateral space syndrome.

Adult↗
PubMed1994

Dysfunction of mouse liver mitochondria induced by 2,2'-azobis-(2-amidinopropane) dihydrochloride, a radical initiator, in vitro and in vivo.

Mouse liver mitochondria were uncoupled in a time dependent by intraperitoneal injection of a radical initiator, 2,2'-azobis-(2-amidinopropane) dihydrochloride (AAPH) (100 mg/kg). State 3 respiration, ADP/O ratio and respiratory control ratio (RCR) were decreased 30 min after injection but there was no effect on state 4 respiration. Lipid peroxidation was increased and oxidative phosphorylation was uncoupled at one hr after drug injection but gradually recovered to normal levels after 14 hr in vivo. State 3 respiration, RCR and ADP/O ratio but not state 4 respiration of isolated mouse mitochondria were inhibited by short term incubation with AAPH in vitro. This inhibitory action was concentration dependent (ID50 = 5 mM) but was not prevented by alpha-tocopherol. AAPH had no effect on electron transport or the membrane potential of these isolated mitochondria. However, mitochondria were uncoupled via lipid peroxidation and swelling by long term incubation with AAPH. These inhibitory effects of AAPH were reduced by its spontaneous degradation not only in vitro but also in vivo. Thus AAPH induces mitochondrial dysfunction by direct action in the early period of treatment and free radicals produced from AAPH mediate mitochondrial swelling via lipid peroxidation in the late period. From these findings, it is concluded that mitochondrial phosphorylation plays an important role in the pathogenesis of liver injury induced by AAPH and that radicals generated by AAPH might be a source of liver injury and mitochondrial dysfunction in vivo.

Amidines↗
PubMed1994

DNA damage by various forms of active oxygens and its inhibition by different scavengers using plasmid DNA.

The degree of DNA damage by the treatment with various molecular species of active oxygen and its inhibition by pretreatment with different scavengers were evaluated using pUC19 plasmid DNA. DNA damage caused by O2-. generated by xanthine-xanthine oxidase system (X-XOD), .OH by Fenton reactions, and OCl- by NaOCl involved the generation of open circle DNA demonstrating single strand breaks. Catalase (Cat), diethylenetriaminepentaacetic acid (DETAPAC), desferroxiamine (Desferal), dimethyl sulfoxide (DMSO) and ethanol (EtOH) all inhibited 60-80% of DNA damage by the generated O2-.. Superoxide dismutase (SOD) inhibited all DNA damages by O2-.. Cat, DETAPAC and Desferal effectively inhibited DNA break by .OH; complete inhibition of .OH-induced DNA break was achieved by addition of DMSO and EtOH. Desferal and EtOH completely inhibited DNA damage by OCl-. These findings suggested that metal ions are associated with the mechanism of DNA damage by all forms of active oxygen species.

DNA Damage↗
PubMed1994

Expression of antral gastrin and somatostatin mRNA in Helicobacter pylori-infected subjects.

OBJECTIVES: We investigated the gene expression of antral gastrin and somatostatin in Helicobacter pylori-infected subjects. Twelve asymptomatic men with normal endoscopic findings participated in this study, four of whom were infected with H. pylori. METHODS: Biopsy specimens of the gastric mucosa were obtained after subjects had fasted overnight. Serum gastrin levels, antral gastrin and somatostatin content, and antral G- and D-cell densities also were measured. RESULTS: Fasting serum gastrin levels were significantly higher in H. pylori-positive subjects than in H. pylori-negative subjects. There were no differences between groups in antral gastrin content, G-cell density, or gastrin mRNA levels. Antral somatostatin content, D-cell density, somatostatin mRNA levels, and the somatostatin mRNA:D-cell density ratio were significantly decreased in H. pylori-positive subjects. CONCLUSIONS: Our results suggest that in addition to reduced antral D-cell density, a suppression of somatostatin synthesis in D-cells may have contributed to the decrease in antral somatostatin in H. pylori-infected subjects.

Adult↗
PubMed1994

Acute hepatic failure with swollen mitochondria and microvesicular fatty degeneration of hepatocytes triggered by free radical initiator.

BACKGROUND: Reye syndrome and acute fatty liver of pregnancy are characterized by acute hepatic failure associated with characteristic pathologic changes of hepatocytes, i.e., microvesicular fatty degeneration with severe mitochondrial swelling. Several animal models of these conditions have been proposed, although none has demonstrated sufficiently similar laboratory and pathologic features. EXPERIMENTAL DESIGN: A single dose of 2,2'-azobis-(2-amidinopropane) dihydrochloride, a free radical initiator, 100 mg/kg of body weight, injected intraperitoneally to BALB/c mice induced a transient decrease in hepatic energy charge, liver mitochondrial respiratory activity, and succinate dehydrogenase activity and a transient increase in blood ammonia level, suggesting hepatic failure. RESULTS: The hepatocytes displayed microvesicular fatty degeneration with severely swollen mitochondria. CONCLUSIONS: This is the first model of acute hepatic failure with microvesicular fatty degeneration of hepatocytes. It suggests a role of free radicals in the pathogenesis of certain types of acute hepatic failure.

Adenine Nucleotides↗
PubMed1993

[MR cisternography using "long echo train length fast spin echo sequence" for demonstrating the inner ear].

Excellent quality of MR cisternography was acquired using "long echo train length fast spin echo sequence" (TR/TE = 2666/200, ETL = 24, 6 or 8 NEX, 3 mm thickness, 0 mm interslice gap, 19 cm FOV, 512 * 384, 2 DFT method). The inner ear anatomy such as canaliculus cochleae or lamina spiralis ossea were well visualized. The VII, VIII th nerve bundles within the internal auditory canal were detectable as 1 to 4 bundles. The vessels in the cerebellopontine angle or the internal auditory canal were also demarcated from the VII, VIII th nerve bundles because of their flow void. Signal to noise ratio seemed to be better than 3 DFT method, however limited spatial resolution in the cranio-caudal direction might require additional sagittal or coronal scan.

Adult↗
PubMed1993

[Breath hold MR cholangio-pancreatography (MRCP) using long echo train length fast spin echo sequence in combination with surface coil].

To test the feasibility of MR cholangio-pancreatography (MRCP) using long echo train length (32) fast spin echo sequence in combination with shoulder surface coil, 20 patients who had had ERCP were examined. Good correlations were acquired between the findings obtained by two modalities in terms of ductal strictures, dilatations and intraductal lesions. MRCP was considered to be an examination of choice in various kinds of pathologies affecting biliary duct as well as pancreatic duct for its non-invasiveness and reasonable image quality.

Adult↗
PubMed1993

Reversible priming and protein-tyrosyl phosphorylation in human peripheral neutrophils under hypotonic conditions.

Hypotonic shock enhanced both formyl-methionyl-leucyl-phenylalanine (FMLP)-induced superoxide (O2-.) generation and tyrosyl phosphorylation of cellular proteins including 120-, 115-, 83-, 63-, and 54-kDa proteins of human peripheral neutrophils. The time course of the enhancement correlated with that of tyrosyl phosphorylation of the 115-kDa protein. The "primed state" was reversed to the nonprimed resting state by changing the conditions from hypotonic to isotonic, with a concomitant decrease in tyrosyl phosphorylation. Genistein inhibited the increase in both O2-. generation and tyrosyl phosphorylation of the 120-, 115-, 63-, and 54-kDa proteins. These results suggest the involvement of tyrosyl phosphorylation of a cellular protein(s) in hypotonic shock-induced priming of neutrophils.

Amino Acid Sequence↗
PubMed1993

Role of histamine2 receptor in increased expression of rat gastric H(+)-K(+)-ATPase alpha-subunit induced by omeprazole.

Omeprazole is a specific inhibitor in vivo of the functioning gastric acid pump, the H(+)-K(+)-adenosinetriphosphatase (ATPase), in the secretory canaliculus of the parietal cell. It has been shown previously that omeprazole in rats led to an increase in the mRNA for the alpha-subunit of the H(+)-K(+)-ATPase. Omeprazole causes a marked increase in circulating gastrin in this species, which in turn stimulates release of histamine from the enterochromaffin-like cell. The possible role of this pathway was investigated by the in vivo administration of famotidine, a potent H2 receptor antagonist. A single intraperitoneal dose of famotidine, 200 mg/kg, produced a transient hypergastrinemia peaking at 3 h and normalizing at 12 h, inhibition of secretion that lasted for 12 h, but no change in the level of the alpha-subunit mRNA or of beta-actin mRNA. In contrast, a single dose of omeprazole, 100 mg/kg, inhibited acid secretion and produced hypergastrinemia, peaking at 12 h, both effects lasting for the 24-h observation period. Omeprazole elevated the alpha-subunit mRNA transiently by more than threefold at 3 h, with normal levels being restored at 24 h. The administration of famotidine 1 h after omeprazole did not change the effects of omeprazole on acid secretion but elevated the gastrin levels further. There was now no elevation of the alpha-subunit mRNA for the first 6 h, but a small increase at 12 h and a further increase to approximately 2.5-fold at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Case report: MR appearance of a retained surgical sponge.

A case of a retained surgical sponge found in the retroperitoneum is presented with findings on magnetic resonance (MR) imaging, computed tomography (CT), ultrasonography (US) and angiography. Among all the performed modalities, a characteristic internal structure of the gauze granuloma was best visualized on MR imaging. If no radio-opaque marker is seen on plain radiography or CT, the folded fabric inner structure visualized on T2-weighted images can be a most important clue to the correct diagnosis of this iatrogenic mass.

Female↗