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Biomedical subjects

S Kato

Publications and source records attributed to S Kato.

At least 739 records · Page 41Linked to original sources
PubMed1996

A quantification of goldfish behavior by an image processing system.

We developed a computer-image processing system to quantitatively score the goldfish behavior. The system was composed of two CCD cameras, set in the upper and side directions of a water tank, two graphics I/O boards (video interface) and an IBM PC/AT compatible computer. From the top and side views through the two CCD cameras, 2-dimensional or 3-dimensional positional coordinates of fish freely moving in an aquarium were acquired over a long period (60 min). A positional distribution histogram of the goldfish was made by measuring the number of coordinates. Goldfish have a tendency to move at the circumference and bottom of a water tank. The velocity of moving goldfish was calculated from the time and distance. The average velocity of goldfish was in the range of 6-36 mm/s. A directional histogram (go straight and turn right or left) of a moving goldfish in an aquarium was made to measure an angle formed by two vectors, which were defined as three (middle to terminal against initial to middle) points in a unitary length (50 mm) of the path of goldfish. Three directions (go straight, right turn and left turn) were quantified as a percentage (59 +/- 12%, 20 +/- 4% and 20 +/- 4%, respectively) of a 1-h-event of moving goldfish. This image processing system thus can make an easy and quantifiable behavioral analysis of moving goldfish.

Algorithms↗
PubMed1996

Stimulation of acid secretion in rat stomach following exposure to taurocholate in the presence of the nitric oxide synthase inhibitor.

1. The role of nitric oxide (NO) in the acid secretory response of the rat stomach following damage was investigated. A rat stomach was mounted in an ex-vivo chamber, perfused with saline, and the potential difference (PD), luminal pH, acid and HCO3- responses were measured before and after the mucosal exposure to 20 mM taurocholate (TC) for 30 min, with or without pretreatment with NG-nitro-L-arginine methyl ester (L-NAME). 2. Exposure of the stomach to TC caused a reduction of PD, a decrease of acid secretion and an increase in luminal HCO-. Pretreatment with L-NAME did not affect such PD and HCO3- responses, but completely attenuated the decreased acid secretory response and rather enhanced this secretion. 3. These effects of L-NAME were significantly antagonized by the co-administration of L-arginine but not D-arginine. The enhanced acid secretory response in the presence of L-NAME was significantly inhibited by prior administration of cimetidine or FPL-52694 (a mast-cell stabilizer). 4. The mucosal exposure to TC significantly decreased the number of mucosal mast cells and increased the luminal histamine output. 5. Damage in the stomach may activate the histamine-dependent acid stimulatory pathway in addition to the NO-dependent inhibitory mechanism, although the latter effect overcomes the former, resulting in a decrease of acid secretion. L-NAME unmasks the stimulation of acid secretion by suppressing the inhibitory pathway.

Animals↗
PubMed1996

Reactive oxygen species involved in the glutamate toxicity of C6 glioma cells via xc antiporter system.

We recently demonstrated that continuous L-glutamate exposure led to cell death in C6 glioma cells over a period of 24-36 h, due to inhibition of cystine uptake through the cystine/glutamate (XC) antiporter. The antioxidant vitamin E provided protection against this effect, supporting the hypothesis that depletion of glutathione might be responsible, resulting from insufficient cystine uptake. To clarify the content of oxidative stress after glutathione depletion, the present study was done to investigate accumulation and target molecules of reactive oxygen species induced by glutamate treatment. The accumulation of reactive oxygen species was increased three-fold as compared to a control culture. Membrane oxidation, as judged by lipid peroxidation, was increased two-fold after glutamate treatment. Cellular ATP content was significantly reduced by glutamate exposure. For the two cytosolic enzymes examined, activity of glyceraldehyde 3-phosphate dehydrogenase was slightly enhanced by glutamate treatment, while activity of glutamine synthetase was not changed. Impairment of nuclear DNA after glutamate exposure was also revealed by nuclear chromatin condensation with DNA fragmentation. Thus, the multiple targets (membrane, cytoplasm and nuclei) of oxygen radicals in glutamate toxicity through the xc antiporter system were evaluated for the first time. Furthermore, prevention from cell death and from cellular toxicity induced by oxygen radicals could be seen using three specific oxygen radical scavengers, catalase, 3,3,5,5-tetramethyl-pyrroline N-oxide and alpha-phenyl-N-t-butylnitrone, without restoring the glutathione deficit. This indicates that radical scavengers did not interact with the xc antiporter system, but directly scavenged the oxygen radicals. Taken together, the data strongly suggest that O2-, H2O2 and OH accumulate in response to oxidative stress after glutathione depletion, resulting in glutamate cell death of C6 glioma cells.

Adenosine Triphosphate↗
PubMed1996

Malignant hyperthermia during epidural anesthesia.

We anesthesized a patient susceptible to malignant hyperthermia (MH) three different times by epidural anesthesia with different types of local anesthetics. His skinned fiber test showed a marked acceleration of calcium (Ca2+)-induced Ca2+ release (CICR). When ester type local anesthetic was used for ankle contracture repair, MH signs appeared following the release of the tourniquet. CICR test is reliable for diagnosing different types of MH.

Adolescent↗
PubMed1996

Effect of omeprazole in the treatment of refractory acid-related diseases in childhood: endoscopic healing and twenty-four-hour intragastric acidity.

OBJECTIVE: To determine the clinical efficacy of once-daily treatment with omeprazole in refractory acid-related diseases in children. METHODS: Endoscopic healing and 24-hour intragastric pH values were assessed in 13 patients with refractory reflux esophagitis (n = 5), refractory and/or giant duodenal ulcer (n = 6), or giant gastric ulcer (n = 2). The mean dose of omeprazole was 0.6 mg/kg per day (range, 0.3 to 0.7 mg/kg per day). Pharmacokinetic studies of omeprazole were performed in seven patients. RESULTS: The cumulative healing rates at 2, 4, 6, and 8 weeks of treatment were 46%, 85%, 92%, and 92%, respectively. Esophagitis in one patient did not heal despite increases in doses of up to 1.6 mg/kg per day (40 mg/day). The mean intragastric pH of omeprazole-treated patients was 5.2 (range, 3.0 to 6.6) and mean hydrogenion activity was 1.78 mmol/L (range, 0.01 to 10.42 mmol/L). There was wide interindividual variation in the reduction of gastric acid production. Mean intragastric H+ activity in omeprazole-treated patients was significantly lower than that of control subjects (p < 0.005) and that of patients treated with histamine type 2(H2)-receptor antagonists (p < 0.05). Mean intragastric H+ activity was not significantly correlated to the area under the concentration-time curve of omeprazole. No severe adverse effects were reported during treatment or at follow-up. CONCLUSIONS: Omeprazole has a potent antisecretory effect and is a suitable alternative for short-term treatment of refractory acid-related diseases; a relatively low dose (0.6 mg/kg per day) appears to be optimal in most patients. Unhealed esophagitis at 8 weeks of treatment was considered to be refractory to omeprazole.

Anti-Ulcer Agents↗
PubMed1996

Effect of pituitary adenylate cyclase-activating polypeptide on exocrine and endocrine secretion in the ovine pancreas.

The role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the regulation of exocrine and endocrine pancreas was investigated in conscious sheep. Intravenous infusions of PACAP-27 and PACAP-38 (1, 3, and 10 pmol/kg/min) for 10 min during phase II of the duodenal migrating myoelectric complex accelerated pancreatic protein and amylase outputs dose-dependently. The responses in enzyme secretion to both PACAPs at the highest doses were inhibited significantly by atropine infusion (14.4 nmol/kg/min). Vasoactive intestinal polypeptide (VIP) at 3 pmol/kg/min significantly accelerated protein but not amylase outputs, although the response to the highest dose was not significantly influenced by atropine. PACAP-27 and VIP increased pancreatic juice flow and bicarbonate output dose-dependently; however, the responses to the highest dose were not altered significantly by atropine. On the other hand, intravenous injection of PACAP-38 (100 pmol/kg) did not influence basal plasma concentration of insulin, glucagon, and glucose. Moreover, PACAP-38 (1-100 pmol/kg) altered neither pancreatic endocrine response to intravenous infusion of glucose (20 mumol/kg/min) not that to n-butyric acid (33 mumol/kg/min). These results suggest that PACAP contributes to the regulation of exocrine secretion of the ovine pancreas but not to endocrine secretion. PACAP appears to accelerate pancreatic enzyme secretion mostly via the cholinergic nerves.

Animals↗
PubMed1996

Isolation and characterisation of Kasumi-1 human myeloid leukaemia cell line resistant to tumour necrosis factor alpha-induced apoptosis.

Tumour necrosis factor (TNF)-alpha induces apoptosis in a human acute myeloid leukaemia cell line, Kasumi-1. To examine the role of protein phosphorylation in signal transduction of TNF-alpha-induced apoptosis, a variant cell line resistant to TNF-alpha was established by an intermittent challenge of Kasumi-1 cells with increasing concentrations of TNF-alpha for 6 months. The mechanism of resistance to TNF-alpha appears to be in the post-receptor pathway because expression of p55 TNF receptor in the variant cells is increased compared with that of the parental Kasumi-1 cells. In renaturation assays, TNF-alpha induced a rapid activation of different protein kinases of different molecular weights, including the 50 kDa protein kinase (PK50) followed by the 35 kDa protein kinase (PK35), in the parental Kasumi-1 cells. The dose-response of TNF-alpha required to activate PK50 and PK35 was closely related to concentrations of TNF-alpha that induced apoptosis. Treatment of Kasumi-1 cells with ceramide also activated PK35. In TNF-resistant variant cells, activation of PK35 in response to TNF-alpha or ceramide was practically nil. These findings suggest that activation of PK35 through the ceramide pathway may play an important role in signal transduction of TNF-alpha in the Kasumi-1 cell line, while the decreased activation of PK35 may explain the insensitivity of the variant cells towards TNF-alpha.

Apoptosis↗
PubMed1996

Functional coupling of the delta-, mu-, and kappa-opioid receptors to mitogen-activated protein kinase and arachidonate release in Chinese hamster ovary cells.

To examine whether the mitogen-activated protein kinase (MAPK) cascade and phospholipase A2 (PLA2) are involved in the signal transduction mechanism of the opioid receptor, the delta-, mu-, and kappa-opioid receptors were stably expressed from cDNA in Chinese hamster ovary cells. Activation of the delta-, mu-, and kappa-receptors by agonists induced a rapid and transient increase in MAPK activity accompanied by reduced electrophoretic mobility of the 42-kDa isoform of MAPK (p42), probably owing to phosphorylation. The opioid receptor-mediated increase in MAPK activity was suppressed not only by pretreatment with genistein, a tyrosine protein kinase inhibitor, but also by prolonged exposure to phorbol 12-myristate 13-acetate and pretreatment with GF 109203X, a selective protein kinase C (PKC) inhibitor, suggesting the involvement of PKC as well as tyrosine protein kinase. Furthermore, stimulation of the delta-, mu-, and kappa-receptors with opioid agonists in the presence of A23187, a calcium ionophore, resulted in an increase in arachidonate release, suggesting that PLA2 is activated by the opioid receptors when the intracellular Ca2+ concentration is elevated. Both MAPK activation and increase in arachidonate release mediated by the opioid receptors were abolished by pretreatment with pertussis toxin, suggesting that these responses are mediated by Gi or Go types of GTP-binding regulatory proteins.

Animals↗
PubMed1996

Role in nitric oxide in Kupffer cell-mediated hepatoma cell cytotoxicity in vitro and ex vivo.

The metabolic change in tumor cells (AH70, a rat hepatoma cell line) cocultured with isolated rat Kupffer cells were visualized and analyzed by a laser scanning confocal imaging system. When AH70 cells were cocultured with Kupffer cells, fluorescence intensity of rhodamine 123 (Rh123) decreased, indicating the reduction of mitochondrial function. The reduction in Rh123 was eliminated by NG-monomethyl-L-arginine (L-NMMA), an analogue of L-arginine, suggesting the involvement of nitric oxide (NO). Two hour after the cells were cocultured, membrane compromised AH70 cells which were observed as propidium from 2.8% to 25%. This increase was also attenuated by L-NMMA, suggesting that Kupffer cell-mediated injury of tumor cells largely depends on NO. The concentrations of NO-2 + NO-3 in the culture medium markedly increased after coculture of AH70 cells with Kupffer cells. Moreover, NO synthase (NOS) activity in Kupffer cells significantly increased after coculture. These in vitro results suggest that NO mediates Kupffer cell-induced tumor cell damage characterized by reduced mitochondrial function and diminished barrier function. In the ex vivo study of the perfused liver to which AH70 cells were injected via the catheter inserted into the portal vein, some AH70 cells were arrested in the upper stream of sinusoid and the fluorescence intensity of Rh123 in adherent AH70 cells decreased in a time-dependent manner within 2 hours. The number of PI-positive AH70 cells also increased 2 hours after the injection of AH70 cells. These changes were inhibited by either administration of N omega-L-nitroarginine-methylester (L-NAME) to perfusate or pretreatment of the rat liver with GdCl3, which is known to deplete Kupffer cell function. Thus, the present study suggests that NO from Kupffer cells induces mitochondrial dysfunction in tumor cells followed by membrane barrier dysfunction in the liver sinusoid.

Animals↗
PubMed1996

Fructose stimulates shedding of cytoplasmic droplets from epididymal boar spermatozoa.

The aim of the present study was to establish the presence of an inducer(s) for the shedding of cytoplasmic droplets from boar spermatozoa after ejaculation. Cauda epididymal spermatozoa were incubated with seminal plasma, seminal vesicular fluid (SVF) or chemical agents at 39 degrees C for 30 min. After fixation and staining, percentages of spermatozoa without a droplet were determined. In the samples incubated with seminal plasma, SVF and a filtrate of SVF obtained after passage through an ultrafilter (molecular weight cut-off, 10,000), 43%, 60-69% and 43% of the spermatozoa were without a droplet respectively. The percentage of spermatozoa without a droplet after incubation with D-fructose (1.0 mM), which was one of the energy substrates included in SVF, was 76%. Furthermore, percentages increased to 93% and 90% with the addition of caffeine (2.0 mM) and N6, 2'-O-dibutyryl cyclic adenosine 3',5'-monophosphate (1.0 mM), respectively, but decreased to 48% with the addition of imidazole (2.0 mM). Based on these results, it is suggested that the shedding of cytoplasmic droplets from boar spermatozoa is induced by fructose originating from SVF. It also appears that this event is mediated by increasing the concentration of intracellular cyclic adenosine 3',5'-monophosphate.

Animals↗
PubMed1996

Distribution of 7-alkyl-2'-deoxyguanosine adduct levels in human lung.

Human lung tissue is frequently studied as a target organ for DNA damage from carcinogen-DNA adducts. In order to assess the distribution of carcinogen-DNA adducts in human lung, we measured 7-methyl-2'-deoxyguanosine-3'-monophosphate (7-methyl-dGp), 7-ethyl-2'-deoxyguanosine-3'-monophosphate (7-ethyl-dGp) and 4-hydroxy-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts in different lobes. The first two result from exposure to N-nitrosamines, including tobacco-specific nitrosamines, and the latter only from tobacco-specific nitrosamines. Using a chemically-specific 32P-postlabeling assay for 7-alkyl-2'-deoxyguanosines, adducts were measured in eight separate lung segments of ten autopsy donors. 7-Methyl-dGp levels were detected in all eighty samples (range from 0.3 to 11.5 adducts/10(7) dGp; mean 2.5 +/- 2.3 adducts/10(7) dGp). 7-Ethyl-dGp were detected in all but five of the samples (range from <0.1 to 7.1 adducts/10(7) dGp; mean 1.6 +/- 1.7 adducts/10(7) dGp). 7-Methyl-dGp levels were approximately 1.5-fold higher than 7-ethyl-dGp levels, and they were positively correlated with each other in most individuals. There was no consistent pattern of adduct distribution in the different lobar segments. Most individuals, especially those with the lowest levels, had similar levels among the lobes, while those with the highest levels had a widely variable pattern ranging as much as ten-fold. Moreover 7-methyl-dGp and 7-ethyl-dGp levels in all people showed a highly significant inter-individual variation (P = 0.0001). The levels of 7-alkyl-2'-deoxyguanosine among individuals could not be explained by differences in tobacco exposure (measured by serum cotinine), onset of death, gender, age, race, blood ethanol, or ventilation and perfusion variability. In an effort to corroborate 7-alkyl-2'-deoxyguanosine adducts variability among lobes or individuals, we sought to determine a correlation with HPB-releasing DNA adducts as an independent marker of tobacco exposure. However, this tobacco- specific carcinogen-DNA adduct could not be detected in four individuals tested (detection limit: 0.3 adducts per 10(7) dGp). Based upon the lack of 7-alkyl-2'-deoxyguanosine discernible adduct patterns, no conclusions could be drawn regarding a potential relationship to lobar cancer incidence. The results indicate that in studies of carcinogen-DNA adducts, such as 7-alkyl-dGp in human lungs, for most individuals a random lung sample would be representative of other parts of the lungs. Some individuals however might be misclassified due to highly variable 7-alkyl-dGp levels.

Adult↗
PubMed1996

Cloning and expression of cDNA encoding a human ubiquitin-conjugating enzyme similar to the Drosophila bendless gene product.

cDNA encoding a novel human ubiquitin-conjugating enzyme has been cloned from an epidermoid carcinoma KB cDNA library. This clone encodes a protein of 152 amino acids with a calculated M(r) of 17,137. The amino acid sequence showed 80% identity with the Drosophila's bendless gene product (ubiquitin-conjugating enzyme E2). The corresponding transcripts are highly expressed in heart, skeletal muscle, and testis. The product expressed in Escherichia coli exhibited the ability to form a thiol ester linkage with ubiquitin in a ubiquitin-activating enzyme E1-dependent manner. These results suggest that the obtained cDNA encodes a novel human E2 which may be involved in protein degradation mainly in the muscles and testis.

Amino Acid Sequence↗
PubMed1996

Steroid hormones differentially induce transcription of the chicken ovalbumin gene, but stabilize the mRNA with the same half-life.

The stabilization of chicken ovalbumin (OVA) mRNA by different classes of steroid hormones (estrogen, progesterone, glucocorticoid, and androgen) was studied in the oviducts of chicks treated with combinations of four steroids. The combination of estrogen with progesterone, glucocorticoid, or androgen enhanced the induction of the OVA gene more than did estrogen alone. Run-on analysis of the isolated oviduct nuclei to measure the transcription rate of the OVA gene showed that the enhanced induction of the OVA gene by the combined hormone treatments was partly caused by an increased rate of transcription. The half-life of OVA mRNA as determined using a transcription inhibitor (actinomycin D) was estimated to be about 24 h irrespective of the hormone treatment, though the half-life was about 6 h in the absence of hormones. These results suggested that the prolongation of the half-life of OVA mRNA by steroid hormones is constant irrespective of differential transcription rates of the OVA gene.

Animals↗
PubMed1996

Electrophoretic characterization of boar epididymal antiagglutinin.

Boar epididymal antiagglutinin, previously shown to inhibit sperm head-to-head agglutination, was purified from cauda epididymal plasma by precipitation with ammonium sulfate, anion-exchange chromatography, and reverse-phase HPLC, and was characterized by electrophoretic and membrane blotting techniques. Blotting techniques, using the ECL Glycoprotein Detection System (Amersham Life Science, Buckinghamshire, UK) and wheat germ agglutinin (WGA)-peroxidase, established the presence of sialic acid residues on purified antiagglutinin. Removal of sialic acid residues from antiagglutinin greatly reduced its immunoreactivity with the specific antiserum. Further purification by two-dimensional PAGE established the presence of one major and two minor forms that cross-reacted with the antiserum, with only the major form reacting with WGA-peroxidase. Extracts of washed epididymal spermatozoa contained a polypeptide with the same electrophoretic mobility as the major form. Additionally, the antiserum detected cross-reacting material in seminal plasma and in extracts from ejaculated spermatozoa. When spermatozoa were incubated under conditions shown to promote capacitation, the cross-reacting material could not be detected in sperm extracts. These results are consistent with the following conclusions: 1) antiagglutinin contains sialic acid residues that may be related to its immunoreactivity and molecular heterogeneity, and 2) either sperm-bound antiagglutinin is released or its epitope recognized by the antiserum is altered after ejaculation and in vitro capacitation.

Animals↗
PubMed1996

Effect of cholera toxin on glucose absorption and net movements of water and electrolytes in the intestinal loop of sheep.

This study was designed to evaluate the effect of cholera toxin on glucose absorption and net movement of water and electrolytes in the jejunal loop of sheep. Intraluminal perfusion was performed at the rate of 1 ml/min with isotonic 10 mM glucose solution. Osmolality was adjusted by adding NaCl, and the outflow solution was collected every 10 min. After a 30 min control period, cholera toxin was applied intraluminally for 30 min at doses of 30, 60, and 120 micrograms/loop. In the control period, water, sodium and chloride were absorbed, while potassium and bicarbonate were secreted. Cholera toxin reversed the net absorption of water, sodium and chloride to net secretions, and this secretory response to cholera toxin was dose-dependent. Bicarbonate secretion was stimulated dose-dependently by cholera toxin. Potassium secretion was also increased at all doses, though this response was not dose-dependent. The net glucose absorption was decreased dose-dependently by cholera toxin. In conclusion, these results indicate that cholera toxin stimulates water and electrolyte secretion, and inhibits glucose absorption in the jejunal loop of sheep.

Animals↗
PubMed1996

Changes in gastric HCO-3 secretory response to NG-nitro-L-arginine methyl ester in rats following repeated administration.

The effect of repeated administration of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on gastric HCO-3 secretion was examined using ex vivo chambered stomachs of anaesthetized rats. Intravenous administration of L-NAME (5 mg/kg) increased gastric HCO-3 secretion with a concomitant rise in arterial blood pressure (BP). The HCO-3 stimulatory action of L-NAME diminished when rats were pretreated with L-NAME (20 mg/kg, p.o., twice daily) for 1 or 3 days and an inverse relationship was found between the degree of secretory stimulation and the period of pretreatment. The increased BP response to L-NAME was also significantly lessened following repeated pretreatment; basal BP showed a stepwise increase during repeated pretreatment and did not change at all in response to i.v. L-NAME after 3 days pretreatment. When delta HCO-3 output induced by i.v. L-NAME was plotted against delta BP (from basal values) during repeated pretreatment with L-NAME, a significant relationship was found between these two factors. The reduction in the HCO3 secretory response to L-NAME was restored when animals were pretreated with L-arginine (500 mg/kg, i.p., twice daily) together with L-NAME. However, prostaglandin E2 (300 micrograms/kg, i.v.) caused a gastric HCO-3 secretory response similar to L-NAME, regardless of whether rats had been pretreated with L-NAME or not. In contrast, the attenuation by L-NAME of the acid (0.2 nmol/L HCl)-induced gastric hyperaemic response was not influenced by repeated pretreatment with L-NAME. We conclude that repeated p.o. pretreatment with L-NAME reduces the HCO-3 stimulatory action of i.v. L-NAME and that this phenomenon may be explained by the lack of further elevation of BP in response to i.v. L-NAME following repeated pretreatment with this agent. Thus, the stimulation of HCO-3 secretion by i.v. L-NAME may be causally related with increased BP in response to this agent.

Administration, Oral↗
PubMed1996

Acute disseminated encephalomyelitis associated with Mycoplasma pneumoniae infection.

An 8 year old girl with acute disseminated encephalomyelitis (ADEM) is described. Elevated serum antibody titers suggested recent Mycoplasma pneumoniae infection. T2-weighted image of magnetic resonance imaging (MRI) disclosed multiple lesions of high signal intensity in bilateral basal ganglia and thalami as well as in the white matter. Postcontrast T1-weighted image revealed an enhanced lesion in the deep white matter. She showed rapid clinical improvement in response to corticosteroid therapy. The lesions had disappeared completely on MRI performed 10 weeks after the onset. ADEM is believed to be a demyelinating disorder of probable autoimmune etiology. MRI findings in this case may support the hypothesis that the primary pathological event is vascular injury and demyelination occurs only as a secondary phenomenon.

Basal Ganglia↗