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Biomedical subjects

T Sakai

Publications and source records attributed to T Sakai.

At least 577 records · Page 32Linked to original sources
PubMed1997

Remarkable growth of the internal mammary artery used for systemic-to-pulmonary artery shunt in a patient with cyanotic heart disease.

The left internal mammary artery-to-the left pulmonary artery shunt was created in a 16-year-old boy with single ventricle, severe pulmonary stenosis palliated by Glenn shunt at the age of two. Four years follow-up angiogram demonstrated a significant increase of the diameter of the left internal mammary artery from 4 to 7 mm. The internal mammary artery is a good alternative conduit for a systemic-to-pulmonary artery shunt for a cyanotic heart disease because of its growth potential.

Abnormalities, Multiple↗
PubMed1997

Ammonia inhibits proliferation and cell cycle progression at S-phase in human gastric cells.

Helicobacter pylori (Hp) has strong urease activity and produces a large amount of ammonia in the stomach. In animal studies, ammonia was shown to accelerate cell kinetics of gastric mucosa, and long-term exposure of the stomach to ammonia leads to mucosal atrophy. To understand this process, we examined the effects of ammonia on the growth and cell cycle progression of human gastric cancer cell lines (HGC-27, MKN1, MKN45) using flow-cytometric analysis. In each cell line, ammonia inhibited the cell growth in a dose-dependent manner and caused significant accumulation of S-phase cells at a cytostatic dose. DNA synthesis of HGC-27 cells treated with ammonia was also suppressed to about 50% of that of the untreated cells. Similar effects were observed on addition of ammonium chloride at the same concentration, while adjusting the pH of the media with NaOH alone to that with the cytostatic dose of ammonia did not affect the cell cycle progression. These observations indicate that ammonia induces S-phase arrest in gastric cells independently of pH.

Adenocarcinoma↗
PubMed1997

Effect of antipsychotic drugs on the gene expression of NMDA receptor subunits in rats.

It has been hypothesized that glutamatergic neurons play an important role in clinical manifestations of schizophrenia and that the therapeutic effect of antipsychotic drugs is related to glutamatergic neurotransmission. To elucidate the effect of antipsychotic drugs on glutamatergic transmission, we examined gene expressions of NMDA receptor subunits R1, R2A, R2B and R2C in the whole brains of rats after acute and chronic administrations of haloperidol and sulpiride, using the Northern blot technique. The levels of NMDAR2B mRNAs decreased after the acute administration of haloperidol, but showed no change after the chronic administration. The levels of NMDAR2A and R2B mRNAs decreased after the acute administration of sulpiride, whereas the levels of R2A and R2B increased following the chronic administration. Neither haloperidol nor sulpiride influenced NMDAR1 mRNA levels. These data support differential expression of NMDA receptor subunits in rats upon treatment with haloperidol and sulpiride. The results imply that NMDAR2 subunits may be crucial in the regulation and modification of antipsychotic drugs.

Animals↗
PubMed1997

Ischemia/reperfusion injury in the rat colon.

This study investigated metabolic and biochemical consequences of colonic ischemia/reperfusion (I/R) in the rat and evaluated whether antioxidants prevent I/R-induced functional damage in the rat colon. The surgical preparation involved a 10 cm segment of the colon and occlusion of the superior mesenteric artery (SMA) to induce I/R. Arterial blood from the aorta and venous blood from the superior mesenteric vein (SMV) was collected to measure blood gases, lactic acid (LA) and arachidonic acid (AA) metabolites. Tissue xanthine oxidase (XO) and thiobarbituric acid (TBA) derivatives were measured before and after reperfusion. In addition, vascular and mucosal permeability, and the effect of MDL 73404 (a water soluble vitamin E analog) and 5-aminosalicylic acid on LA, AA, XO and TBA was measured. After ischemia, the colon displayed a metabolic shift from aerobic to anaerobic course by increasing lactic acid production in the colon (183% increase in SMV lactate level compared 87% in the SMA; p < 0.03). After 10 minutes of reperfusion, circulating 6-keto-prostaglandin F1 alpha increased by 3.85 fold (p < 0.001) and thromboxane B2 increased by 2 to 3 fold. An Ischemia time longer than 60 minutes was required to cause changes in tissue XO levels. Tissue TBA levels showed a good dose response corresponding with I/R time. I/R (60 minutes) caused a three and 16 fold increase (p < 0.01) in vascular and mucosal permeability, respectively. MDL 73404 and 5-aminosalicylic acid significantly inhibited the vascular permeability and decreased LA, AA, XO and TBA. These observations provide the first direct experimental evidence for I/R-induced damage in the colon and some of its effects can be reversed by conventional and novel antioxidants.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

A monoclonal antibody, DL10, which recognizes a sugar moiety of MHC class I antigens expressed on NK cells, NK+ T cells, and granulocytes in humans.

One mAb, DL10, was established from mice injected with dolphin lymphocytes. In addition to its reactivity against all dolphin lymphocytes, it reacted with some human leukocytes, including NK cells, NK+ T cells, and granulocytes. When its reactivity was examined in various animals, bovine, ovine, and equine leukocytes were DL10+. Murine, rat, and canine leukocytes were DL10-. Although the reactivity of DL10+ was similar to those of CD56 and CD57 antigens in humans, the actual molecules it recognized were different. Thus, all reactivity of DL10 disappeared after treatment of cells with glycopeptidase or after culture of cells with tunicamycin. Furthermore, the immunoprecipitation method revealed that DL10 indirectly recognized the heavy chain (45kD) of MHC class I antigen in humans and animals. Considering data from analysis of the N-terminal amino acid sequence of the DL10 molecule and the HLA typing of reactive cells, DL10 recognized a sugar moiety of some monomorphic MHC antigens and polymorphic MHC antigens such as HLA-B60 and -B61. If the donors are HLA-B60- and -B61 (> 80% in Japan and > 95% in the United States), DL10 would appear to be a very useful agent for the detection of pan-NK+ T cells.

Amino Acid Sequence↗
PubMed1997

Sodium azide induces relaxation of the canine gastric body by activating a guanylate cyclase-dependent pathway.

In order to study the inhibitory mechanism by which sodium azide eliminates smooth muscle contraction in vivo and in vitro, gastrointestinal motility was monitored via chronically implanted force transducers in the stomach and duodenum of conscious dogs. Circular smooth muscle strips with myenteric plexus from the canine gastric body were used for in vitro measurement of isometric tension. In conscious dogs, sodium azide (50 micrograms kg-1, i.v.) abolished both the spontaneously occurring phase III contractions and postprandial motility. Exogenous motilin (100 ng kg-1)- and bethanechol (50 micrograms kg-1)-induced contractions were also abolished by sodium azide. In vitro, sodium azide and electrical field stimulation (EFS) caused a concentration- or frequency-dependent nonadrenergic noncholinergic relaxation in the gastric body strips. The relaxation induced by EFS, but not sodium azide, was abolished by tetrodotoxin. NG-nitro-L-arginine and oxyhaemoglobin failed to attenuate the relaxant effect of sodium azide, but strongly inhibited EFS-induced relaxation. Methylene blue inhibited both sodium azide- and EFS-induced relaxation. cGMP concentrations in muscle strips were markedly increased by sodium azide. These findings indicate that sodium azide induces relaxation in the canine gastric body through a direct action on smooth muscle, by activating a guanylate cyclase-dependent pathway; endogenous NO synthesis does not participate in this inhibitory mechanism.

Adrenergic alpha-Antagonists↗
PubMed1997

Effect of 5-hydroxytryptamine on gastrointestinal motility in conscious guinea-pigs.

Many studies have suggested that 5-hydroxytryptamine (5HT, serotonin) plays an important role in the control of gastrointestinal motility. However, most of these studies have been carried out on guinea-pig ileum in vitro. Therefore, we investigated the mechanisms of action of 5HT on gastrointestinal motility in conscious guinea-pigs. In order to investigate the effects of 5HT on gastrointestinal motility, extraluminal force transducers were sutured onto the serosal surfaces of the gastric antrum, duodenum and ileum and 5HT was infused intravenously. One of three types of 5HT antagonist or atropine was given before a 5HT infusion of 3.0 micrograms kg-1 min-1 was started. Regular cyclic patterns were observed from the gastric antrum to the ileum in both the fasted and fed states. 5HT increased the contraction amplitudes at all sites. 5HT-induced contractions in the gastric antrum and duodenum were significantly inhibited by methysergide, ondansetron and atropine, but not by ketanserin. In the ileum, only atropine inhibited 5HT-induced contractions. These results suggest that 5HT increases the gastrointestinal contraction amplitude mainly via a cholinergic pathway. 5HT3 receptors and 5HT1-like and/or 5HT2C receptors appear to be responsible for 5HT-induced gastric antral and duodenal contractions, but 5HT receptors other than 5HT1-like, 5HT2A, 5HT2C and 5HT3 receptors induce ileal contractions.

Animals↗
PubMed1997

On the morphology of the brachial plexus of the platypus (Ornithorhynchus anatinus) and the echidna (Tachyglossus aculeatus).

Four forelimbs of 3 platypuses and 3 forelimbs of 2 echidnas were examined to study the precise form of the brachial plexus and to clarify the structural characteristics of the brachial plexus in phylogeny. The spinal components contributing to the plexus (C4-T2) and the formation patterns of the 3 trunks of the plexus were the same as those generally observed in mammals. In the cranial half of the brachial plexus from C4, 5 and 6 in monotremes, division into the ventral bundle (lateral cord) and dorsal bundle (axillary nerve) is clear, as in other mammals. However, for monotremes, in the caudal half of the plexus from C7 and T1 (+T2) and the nerves arising from the caudal plexus there is no definite division into the ventral and dorsal bundles, which distribute to the flexor and extensor parts of the forelimbs, respectively. The lower trunk of the monotreme brachial plexus forms a cord which contains both ventral and dorsal components. This characteristic diverges from the generally accepted idea that the tetrapod limb plexus is divided clearly into 2 layers: a dorsal layer for extensors and a ventral layer for flexors of the limb. Considering the incomplete dorsoventral division of forelimb nerves in some reptiles and urodeles, the caudal half of the monotreme brachial plexus has characteristics in common with those of lower tetrapods.

Animals↗
PubMed1997

Clinical efficacy of lactulose in cirrhotic patients with and without subclinical hepatic encephalopathy.

Seventy-five cirrhotic patients with hyperammonemia in the past or at the time of the study were randomly divided into two groups (treated with lactulose or nontreated) in 14 hospitals in Japan. Thirty-six cirrhotic patients were diagnosed as having subclinical hepatic encephalopathy (SHE), and 39 were diagnosed as non-SHE. SHE was diagnosed when the results of all three of the quantitative psychometric tests used (number connection test, and symbol digit and block design tests of the Wechsler adult intelligence scale [revised]) were abnormal as compared with age-matched normal values. The mean number of abnormal psychometric test results and the prevalence of SHE were used for a quantitative evaluation of the efficacy of the lactulose treatment. Twenty-two of the SHE patients were treated with lactulose (45 mL/d) for 8 weeks, and the other 14 SHE patients did not receive lactulose. In the SHE patients administered lactulose, the results of the quantitative psychometric evaluation were significantly improved at 4 and 8 weeks after the beginning of the lactulose administration. The SHE had disappeared in 10 (50%) of the 20 treated patients at week 8, but it persisted in 11 (85%) of the untreated 13 patients. We concluded that lactulose treatment in cirrhotic patients with SHE is effective with respect to psychometric tests.

Administration, Oral↗
PubMed1997

Increase in serum creatine phosphokinase concentrations after suxamethonium during sevoflurane or isoflurane anaesthesia in children.

We have studied whether sevoflurane or isoflurane anaesthesia modulates the effect of suxamethonium on serum concentrations of enzyme markers of skeletal muscle function in paediatric patients. Eighty patients undergoing bilateral tonsillectomy, aged 5-12 yr, were allocated randomly to receive anaesthesia with either sevoflurane and nitrous oxide or isoflurane and nitrous oxide. Serum creatine phosphokinase (CK), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) concentrations were measured before, and at 30 min and 20 h after induction of anaesthesia. Mean CK concentrations increased from 97.0 (SD 17.3) to 478 (170) iu litre-1 in the sevoflurane group and from 86.9 (22.4) to 628 (223) iu litre-1 in the isoflurane group, 20 h after induction of anaesthesia. Mean peak serum CK concentration in the sevoflurane group (478 (170) iu litre-1) was significantly less (P < 0.05) than that in the isoflurane group (628 (223) iu litre-1). Mean serum AST concentration increased from 17.5 (4.9) to 31.7 (3.5) iu litre-1 in the sevoflurane group and from 17.3 (2.4) to 34.8 (5.7) iu litre-1 in the isoflurane group, 20 h after induction of anaesthesia. Mean peak serum AST concentrations in the sevoflurane group were significantly lower (P < 0.05) than those in the isoflurane group. There were no significant differences in serum ALT or LDH concentrations between the groups either before or after anaesthesia. We conclude that administration of suxamethonium during either sevoflurane or isoflurane anaesthesia caused a marked increase in serum CK concentrations in paediatric patients. The clinical significance of this finding is uncertain.

Anesthetics, Inhalation↗
PubMed1997

Monochloramine-induced cell growth inhibition and apoptosis in a rat gastric mucosal cell line.

Recent studies have indicated that monochloramine (NH2Cl), a reaction product of NH3 and hypochlorous acid, is involved in the pathogenesis of Helicobacter pylori-associated gastric mucosal damage, but how NH2Cl contributes to lesions is unclear. In the present study, the effects of NH2Cl on mucosal cell growth and the cell cycle were evaluated in vitro using a normal rat gastric mucosal cell line RGM-1. Cell viability was assessed by the Trypan Blue dye exclusion test and cell cycle patterns were determined by DNA labeling with propidium iodide and flow cytometric quantification. NH2Cl inhibited the growth of RGM-1 cells in a concentration-dependent manner. Exposure of cells to NH2Cl caused a time- and dose-dependent loss of G1-phase cells with accumulation of G2/M-phase cells, and produced a fraction of subdiploid cells with oligonucleosomal DNA degradation characteristic of apoptosis. NH2Cl-induced apoptosis was confirmed by fluorescent microscopy with Hoechst 33342 and propidium iodide. These results suggest that NH2Cl inhibits gastric mucosal cell growth and induces apoptosis in RGM-1 cells, events that may be important in gastric mucosal damage or atrophy induced by H. pylori infection.

Animals↗
PubMed1997

Recovery of pancreatic tissue perfusion and ATP tissue level after reperfusion in canine pancreas grafts preserved by the two-layer method.

We examined whether pancreas grafts preserved by the two-layer method maintained adenine nucleotides pool as substrates for ATP synthesis before reperfusion and had the ability to recover pancreatic tissue perfusion and synthesize ATP promptly after reperfusion. After preservation by the two-layer cold storage method using EC for 48 h (group 1) or simple cold storage in EC for 48 h (group 2), canine pancreas grafts were autotransplanted. In controls (group 3), canine pancreas grafts were autotransplanted without preservation. Tissue adenine nucleotide concentrations were measured using high-performance liquid chromatography, and pancreatic tissue perfusions were measured using the hydrogen gas clearance method. Graft survival rates were five of five, zero of five, and five of five in groups 1, 2, and 3, respectively. Total adenine nucleotide levels before reperfusion in group 1 were almost the same as in group 2. Furthermore, ATP tissue levels in group 1 before reperfusion were also the same as in group 2. However, tissue ATP levels in group 1 after 2 h of reperfusion (6.71 +/- 1.19 mumol/g dry weight) were significantly higher than group 2 (4.51 +/- 0.51 mumol/g dry weight; p < 0.05). On the other hand, pancreatic tissue perfusions in grafts preserved by the two-layer method (group 1) after 2 h of reperfusion were significantly higher than in group 2. We conclude that oxygenation of pancreas grafts during preservation by the two-layer method allows for ATP synthesis and leads to maintenance of the grafts' ability to recover ATP levels and tissue perfusions after reperfusion.

Adenine Nucleotides↗
PubMed1997

A thymic hormone protects mice from enteropathy during acute graft-versus-host disease.

We have previously reported that a nonapeptide thymic hormone, facteur thymique serique (FTS), is involved in the differentiation and activation of intestinal intraepithelial lymphocytes (i-IEL) in mice. In this study, we examined the effect of FTS treatment on enteropathy in a murine model for acute graft-vs.-host disease (GVHD) induced by injection of parental C57BL/6 splenocytes into unirradiated (C57BL/6 x DBA/2) F1 hybrids. FTS treatment significantly protected mice from developing acute GVHD as assessed by mortality rate, splenomegaly and enteropathy. The infiltration of donor-derived TCR alpha beta i-IEL bearing CD8 alpha beta was significantly inhibited in the small intestine of FTS-treated mice, and the frequencies of apoptosis of crypt cells in the intestinal mucosa were decreased in these mice during acute GVHD. These results suggest that FTS treatment contributes to protection against enteropathy of acute GVHD. Thus, FTS may provide a useful approach to control acute GVHD after blood transfusion or bone marrow transplantation.

Animals↗
PubMed1997

Paracentric inversion of chromosome 9 with schizoaffective disorder.

A 36-year-old man with schizoaffective disorder was found to have a de novo 46 XY inv (9) (q31.2q34.3). Phenotypical abnormalities are short stature, depressed nasal bridge, hypertelorism and slender shoulders. Paracentric inversion of chromosome 9 is a rare chromosome aberration. This case suggests a new candidate region related to schizoaffective disorder.

Adult↗
PubMed1997

A chance SPECT study of ictal aphasia during simple partial seizures.

We report obtaining an ictal single photon emission computed tomographic (SPECT) scan in a right-handed 51-year-old man who had an astrocytoma in the left cerebral hemisphere and simple partial seizures characterized by aphasia. An epileptic seizure producing loss of speech and right-sided facial twitching occurred by chance during a SPECT scan. During the attack, he was unable to speak, but auditory comprehension and writing were intact. Ictal SPECT showed an area of increased perfusion in the left frontal cortex, with the area of highest perfusion involving the left frontal operculum to the inferior part of the left precentral gyrus. Interictal SPECT showed hypoperfusion in the same area. These SPECT findings suggest that the frontal operculum of the dominant hemisphere is one of the regions that can give rise to epileptic aphasia.

Astrocytoma↗
PubMed1997

Haematological findings in captive dolphins and whales.

OBJECTIVE: To examine haematological features in five species of healthy, captive marine mammals. ANIMALS: Twenty bottlenose dolphins (Tursips truncatus), seven Pacific white-sided dolphins (Lagenorhynchus obliquidens), five Risso dolphins (Grampus griseus) and five false killer whales (Pseudorca crassidens). RESULTS AND CONCLUSION: The red blood cell count was 4.21 x 10(12)/L in bottlenose dolphins, 5.32 x 10(12)/L in Pacific white-sided dolphins, 4.35 x 10(12)/L in Risso dolphins and 4.43 x 10(12)/L in false killer whales. The haemoglobin concentration was 1.51 g/L and packed cell volume 44.7% in bottlenose dolphins; the corresponding values were 1.71 g/L and 48.9% in Pacific white-sided dolphins, 1.72 g/L and 49.4% in Risso dolphins, and 1.52 g/L and 47.8% in false killer whales. The white blood cell count was 7.097 x 10(9)/L in bottlenose dolphins, 5.928 x 10(9)/L in Pacific white-sided dolphins, 5.001 x 10(9)/L in Risso dolphins and 7.921 x 10(9)/L in false killer whales. There were no significant differences in these values among bottlenose dolphins and Pacific white-sided dolphins. The proportion of eosinophils in the differential leukocyte count ranged from 10.3% to 11.5% in bottlenose dolphins, Pacific white-sided dolphins and false killer whales, but was only 0.4% in Risso dolphins. The eosinophilic granules were larger in Risso dolphins and false killer whales than in bottlenose and Pacific white-sided dolphins.

Animals↗
PubMed1997

Duration of chronic HCV infection and efficacy of interferon in chronic hepatitis C patients with a history of blood transfusion. The Study Group for Treatment of Hepatitis in the Kyushu Area.

To investigate correlations between the interval between blood transfusion and the start of IFN therapy, and IFN efficacy, we studied chronic hepatitis C patients with a history of blood transfusion. The subjects were 122 patients with chronic hepatitis C and a history of blood transfusion at 64 institutions. The patients were treated with high or low-dose IFN. High-dose therapy consisted of intramuscular injection of human lymphoblastoid interferon (HLBI), 6 x 10(6) IU daily for 2 weeks, then 3 times a week for 22 weeks, and low-dose interferon therapy of intramuscular injection of HLBI, 6 x 10(6) IU daily for 2 weeks, then 3 x 10(6) IU 3 times a week for 22 weeks. Normal serum ALT levels for 6 months or more after completing IFN (complete response) were found in 44/122 (36.2%) patients and HCV RNA was no longer detectable after completing IFN therapy in 19/68 (27.9%). Patients in whom the interval between blood transfusion and the start of IFN therapy was less than 20 years had significantly higher rates of HCV RNA-negative complete response than those in whom the interval was 20 years or more (p < 0.039). When chronic HCV infection is caused by blood transfusion, the efficacy of IFN depends on the duration of chronic HCV infection. Since the duration of HCV infection is a factor in predicting efficacy, early IFN therapy may be more effective.

Adult↗