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Biomedical subjects

T Omata

Publications and source records attributed to T Omata.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Basal studies on the model of circular excisional wounds made on the dorsal skin of rats treated with hydrocortisone].

This study was performed to establish a circular excisional wound model treated with hydrocortisone (HC-P) and to estimate the following parameters in this model: wound area, hydroxyproline (Hyp) content, histological characteristics and microscopical measurements of histological sections. HC-P inhibited the reduction of wound area, the increase in Hyp content and proliferation of granulation tissue in a dose-dependent manner. The application of ZnO ointment significantly accelerated the reduction of wound area and the increased Hyp content in rats treated with HC-P. From these results, we concluded that this experimental model is useful for the objective evaluation of the efficacy of drugs that promote wound healing.

Animals↗
PubMed1991

Effects of the new anti-ulcer drug nizatidine on prostaglandins in the rat gastric mucosa.

The effects of nizatidine (N-[2-[[[2-[(dimethylamino)methyl]- 4-thiazolyl]methyl]thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine , CAS 76963-41-2), a new histamine H2-receptor antagonist, on the content of prostaglandins (PGs) in the rat gastric mucosa at doses that inhibit basal gastric acid secretion were compared with those of two other histamine H2-receptor antagonists, cimetidine and ranitidine. Nizatidine did not inhibit basal gastric acid secretion at a dose of 0.4 mg/kg but showed dose-dependent inhibition at doses of 10, 30, and 100 mg/kg. This drug had no effects on the content of PG in the gastric mucosa when subcutaneously administered at doses of 0.4, 10, 30 and 100 mg/kg once daily for 5 days. Cimetidine and ranitidine administered at doses that markedly inhibit basal gastric acid secretion (250 and 100 mg/kg/d, respectively) had no effects on the content of PG in the gastric mucosa. On the other hand, nizatidine, cimetidine, or ranitidine at concentrations of 1-100 mumols/l did not inhibit in vitro PGE2 synthesis using sheep seminal vesicle microsomes. These results suggest that nizatidine did not affect in vitro PGE2 synthesis and even doses that markedly inhibit gastric acid secretion had no effects on the content of PGs in the gastric mucosa.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Effects of successive doses of nizatidine, cimetidine and ranitidine on serum gastrin level and gastric acid secretion.

Nizatidine (N-[2-[[[2-[(dimethylamino)methyl]- 4-thiazolyl]methyl]thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine , CAS 76963-41-2) is a new histamine H2-receptor antagonist which shows suppression of gastric acid secretion and antiulcer activity. In the present experiment, the effects of single s.c. administration of nizatidine, cimetidine and ranitidine on serum gastrin levels were studied in fasted rats. Nizatidine at 100 mg/kg increased serum gastrin level 3 h after administration, which however, returned to basal level 6 h after administration. Cimetidine and ranitidine at respective doses of 250 and 100 mg/kg markedly increased serum gastrin levels 3 and 6 h after administration. In a previous study, the suppressive effect of nizatidine on basal gastric acid secretion was 82.8% at a dose of 100 mg/kg s.c. in rat pylrus-ligated model. On the basis of these findings, changes in basal gastric acid secretion and serum gastrin level after withdrawal of nizatidine, cimetidine and ranitidine administered for 14 consecutive days were studied. One day after withdrawal, nizatidine at 100 mg/kg showed a tendency to increase the basal gastric acid secretion. However, 3 and 7 days after administration, almost no changes were obtained. Cimetidine at 250 mg/kg showed a tendency to increase the basal gastric acid secretion 7 days after withdrawal of the drug. Ranitidine at 100 mg/kg induced no changes in basal gastric acid secretion after withdrawal. No obvious influences of all drugs on serum gastrin level after withdrawals were obtained. These results indicate that consecutive administration of nizatidine may cause only a transient increase of gastric acid secretion but no hypergastrinaemia after its withdrawal.

Animals↗
PubMed1991

[Organized chronic subdural hematoma; report of two cases].

Two cases of organized chronic subdural hematoma were presented. The first case had a one-year history of disorientation and right hemiparesis. CT scan revealed a low density area with linear high density in its medial margin, suggesting chronic subdural hematoma on the left frontal convexity. Surgery was performed expecting to remove the hematoma. There was, however, only a little fluid inside with thick membranous tissue. The second case, who has Crouzon disease, presented a one-year history of pseudobulbar palsy and tetraparesis after surgery for chronic subdural hematoma and hydrocephalus. The diagnosis of organized subdural hematoma was made at the time of reoperation which was performed expecting to remove the recurrent chronic subdural hematoma. Plain CT, done after admission to our hospital, showed homogeneous low density area remaining in the bilateral frontal convexity. Infusion scan revealed marked enhancement of the medial margin of the low density area. The lesion was demonstrated as a low intensity area by T1-weighted magnetic resonance images (MRI). Marked enhancement was noted around the low intensity area after the infusion of Gd-DTPA. Although it is very hard to make a diagnosis of organized chronic subdural hematoma using only the CT scan preoperatively, combination of the CT scan and MRI with Gd-DTPA enhancement seemed to be very useful for this purpose.

Adult↗
PubMed1990

Sequencing and Modification of the Gene Encoding the 42-Kilodalton Protein in the Cytoplasmic Membrane of Synechococcus PCC 7942.

A 42-kilodalton cytoplasmic membrane protein is synthesized when high CO(2)-grown cells of Synechococcus PCC 7942 (Anacystis nidulans R2) are exposed to low CO(2). The structural gene for this protein (cmpA) has been cloned and sequenced and shown to encode a 450 amino acid polypeptide with a molecular mass of 49 kilodalton. A deletion mutant lacking the 42-kilodalton protein was obtained by transformation of Synechococcus PCC 7942 following in vitro mutagenesis of the cloned gene. There were no significant differences between the mutant and wild-type cells in their growth rates under either low or high CO(2) conditions. The activity of inorganic carbon (C(i)) transport in the mutant was as high as that in the wild-type strain. In both types of cells, CO(2) was the main species of C(i) transported and the activities of CO(2) and HCO(3) (-) transport increased when high CO(2)-grown cells were exposed to low CO(2). We conclude that the 42-kilodalton protein is not directly involved in the C(i)-accumulating mechanism of Synechococcus PCC 7942.

Journal Article↗
PubMed1990

[Effects of the anti-ulcer agents on the amine contents and regulating enzyme activity of gastric mucosa during the healing process of acetic acid induced gastric ulcer in rats].

In order to elucidate the action of an H2 blocker (cimetidine) and gastric mucosal protection agents (sucralfate and sofalcone) on the relapse and recurrence of gastric ulcer, the effects of cimetidine, sucralfate and sofalcone on the contents of histamine and serotonin and histidine decarboxylase (HDC) activity in the gastric mucosa were examined in the ulcer region and the intact region at the 10th day after the operation to produce acetic acid-induced gastric ulcer in rats. The following results were obtained: 1) HDC activity in the gastric mucosa of rats treated with cimetidine (100 mg/kg twice daily) tended to increase in the intact region, and it was significantly increased in the ulcer region. 2) Increased HDC activity due to cimetidine treatment was observed at the 10th day after interruption of cimetidine administration. 3) The HDC activity in the gastric mucosa was not changed by the treatment with sucralfate (500 mg/kg/day) and sofalcone (200 mg/kg/day). The results suggest that the increased HDC activity in the gastric mucosa might participate in the relapse and recurrence of gastric ulcer after discontinuation of cimetidine administration.

Acetates↗
PubMed1989

Genetically engineered mutant of the cyanobacterium Synechococcus PCC 7942 defective in nitrate transport.

Nitrate-grown cells of Synechococcus PCC 7942 (Anacystis nidulans R2) contain a 45-kDa protein as a major protein in the cytoplasmic membrane but ammonium-grown cells lack it. A mutant (M45) was constructed by inactivating the gene encoding the 45-kDa protein. M45 did not grow under low concentrations of nitrate but high concentrations of nitrate could support its growth, with the optimal concentration being 40-70 mM. The growth rate of M45 was as high as that of the wild-type cells when ammonium was the nitrogen source. The 45-kDa protein was absent in M45 irrespective of the growth conditions. The activities of nitrate and nitrite reductases were higher in M45 than in wild type. The rate of nitrate-dependent O(2) evolution in wild type measured in the presence of L-methionine D,L-sulfoximine and D,L-glyceraldehyde showed saturation kinetics with respect to nitrate concentration in the external medium. The nitrate concentration required to produce half the maximal rate was 1 muM. In M45, the rate of nitrate-dependent O(2) evolution was nearly zero at nitrate concentrations <1 mM and was linearly increased as the concentration increased. The presumed absence of nitrate transport in M45 demonstrated by these results suggested that the 45-kDa protein is a nitrate transporter.

Journal Article↗
PubMed1989

[Changes in amine contents and regulating enzyme activity of gastric mucosa during the healing process of acetic acid induced ulcer in rats].

Changes in the contents of various amines and histidine decarboxylase (HDC) activity in the gastric mucosa during the healing process of acetic acid induced gastric ulcer in rats were sequentially examined in the ulcer region and intact region at 2, 10, 40, 80, 180 and 365 days after the operation. The following results were obtained: 1) Histamine (HA) content in the ulcer region was decreased as compared with the intact region at 2 and 10 days and returned to the control level in 40 days. After 180 days, the contents in the ulcer region and intact region were also increased as compared with that of the normal control region. 2) Changes in serotonin (5-HT) content as well as HA content were observed. 3) Norepinephrine content in the ulcer region was decreased as compared with the intact region at 2, 10, 80 and 180 days. 4) HDC activity in the ulcer region was decreased as compared with the intact region at 2, 10 and 40 days, and a lower level was maintained still at 180 days. 5) In the relapse and recurrence of gastric ulcer at 365 days, HA and 5-HT contents in the intact region and ulcer region were not different from those in healing rats, but the contents of these amines were higher at 180 days. The results suggest that the change of HA, 5-HT contents and HDC activity in the gastric mucosa may be one of the factors involved in the relapse and recurrence of chronic ulcers.

Acetates↗
PubMed1989

Effect of Z-103 on compound 48/80-induced gastric lesions in rats.

Z-103 (a novel anti-ulcer agent), given p.o. at doses of 30 and 100 mg/kg, significantly prevented gastric lesions induced by compound 48/80 in rats. Z-103 inhibited the histamine release from rat peritoneal mast cells stimulated by compound 48/80 in a dose-dependent manner. Z-103 inhibited the increase in thiobarbituric acid (TBA) reactants induced by a single or repeated administration of compound 48/80 in the gastric mucosa. These observations suggested that the protective effect of Z-103 against compound 48/80-induced gastric lesions may be due to its stabilizing activity toward mast cells and/or an antioxidative effect on the gastric mucosa.

Animals↗
PubMed1989

[Evaluation of gallbladder emptying in patients with chronic liver disease by 99mTc-EHIDA hepatobiliary scintigraphy].

Gallbladder emptying after intramuscular injection of cerulein was investigated by 99mTc-EHIDA hepatobiliary scintigraphy in 23 patients with biliary disease, 55 patients with chronic liver disease, and 21 normal controls. The mean gallbladder ejection fraction in patients with gallstones and liver cirrhosis was significantly reduced compared with normal controls. (gallstones: 56.3 +/- 21.3%, LC with gallstones: 50.8 +/- 29.6%, LC without gallstones: 55.9 +/- 26.7%, vs. normal controls: 74.4 +/- 12.9%, p less than 0.01). The mechanism for sluggish gallbladder emptying in liver cirrhosis is unknown, however impaired emptying with bile stasis provides a potential pathophysiologic basis for the high frequency of pigment stones.

Adult↗
PubMed1987

Adaptation to Low CO(2) Level in a Mutant of Anacystis nidulans R(2) which Requires High CO(2) for Growth.

The mutant E(1) of Anacystis nidulans R(2) requires high CO(2) concentration for growth but was able to adapt to low CO(2) concentration. This was exhibited by the increased ability to accumulate inorganic carbon within the cells and the large increase in the amount of a 42-kilodalton polypeptide located in the cytoplasmic membrane. The adaptation occurred in E(1) cells at an extracellular CO(2) concentration as high as 0.3%, which was 8 times the concentration for maximal adaptation in R(2) cells. The ability of E(1) cells to exhibit low CO(2) characteristics at a higher CO(2) concentration was attributed to lower intracellular CO(2) concentration.

Journal Article↗
PubMed1987

Energization and activation of inorganic carbon uptake by light in cyanobacteria.

The requirement of the inorganic carbon (C(i)) transport system for light in cyanobacteria was investigated in Anabaena variabilis by the filtering centrifugation technique and in a mutant (E(1)) isolated from Anacystis nidulans using a gas exchange system. C(i) transport capability increased with time of preillumination and decreased following darkening. Full activity could not be obtained by operating either photosystem II (PSII) or photosystem I alone. 3(3,4 Dichlorophenyl)-1,1 dimethylurea strongly inhibited C(i) uptake. Very low activity of PSII was sufficient to activate C(i) uptake. However, in the presence of dithiothreitol PSII activity was not required. We conclude that light may be required to activate as well as to energize C(i) uptake in cyanobacteria.

Journal Article↗
PubMed1987

A Mutant of Synechococcus PCC7942 Incapable of Adapting to Low CO(2) Concentration.

Some properties of a mutant (RK1) of Synechococcus PCC7942, which requires high CO(2) for growth, are described. The photosynthetic affinity for inorganic carbon (C(i)) in RK1 was about 40 times lower than that in the wild type (WT) when grown at 3% CO(2) (H-cells) and did not change during 10 hours of exposure to low CO(2) (air containing 0.04% CO(2)). The gas exchange of WT and RK1 cells was measured using an open gas-analysis system. All the measurements were performed at a CO(2) concentration of 400 microliters per liter under the conditions where photosynthetic CO(2) fixation is inhibited. When the suspension of H-cells of WT or RK1 was illuminated, the rate of CO(2) influx from the gas phase into the suspension was low and addition of carbonic anhydrase during illumination released only a small amount of CO(2) from the medium into the gas phase. The rate of CO(2) influx and the amount of CO(2) released by carbonic anhydrase were increased in WT during low CO(2) adaptation. These changes did not occur in RK1 during exposure to low CO(2). Cytoplasmic membrane from H-cells of WT or RK1 contained small amount of 42-kilodalton polypeptide. Exposure of RK1 to low CO(2) did not have significant effect on the amount of 42-kilodalton polypeptide, while the same treatment on WT resulted in a large increase of this polypeptide. The RK1 mutant appears to be defective in its ability to utilize the intracellular C(i) pool for photosynthesis and also to transmit a low CO(2) signal for inducing the functional and compositional changes observed in WT during low CO(2) adaptation.

Journal Article↗
PubMed1987

Interferon induction by transfection of Sendai virus C gene cDNA.

To elucidate the mechanism of interferon (IFN) induction on virus infection, we constructed two types of plasmids by inserting a part of the cDNA of the Sendai virus into a simian virus 40-derived expression vector (pSV2-0). One, pSV2-PC, contained the P + C gene, which codes for the P and C proteins in overlapping reading frames, and the other, pSV2-C, contained only the C gene. After transfecting the plasmids into mammalian cells, we determined the IFN activity in the culture medium. We found that the level obtained with pSV2-PC was significantly positive but very low, whereas that obtained with pSV2-C was as high as or even higher than that observed in the culture medium after Sendai virus infection. By cleaving pSV2-C between the simian virus 40 promotor and the C gene or by inserting a stop codon within the C gene [pSV2-C(stop)], induction of IFN was greatly diminished. In Northern blot analyses of the transcripts obtained from the cells transfected with the plasmids with cDNA to the P + C gene as a probe, the transcript having the expected size was detected with both pSV2-C and pSV2-C(stop), whereas none was detected with cleaved pSV2-C or pSV2-0. The results indicate that both transcription and translation of the C gene seem to be required for IFN induction after Sendai virus infection.

Animals↗
PubMed1987

[Statistical analysis of urolithiasis].

During the 13 years from July, 1971 to August, 1984, 1896 patients were diagnosed as urolithiasis at our University Hospital. These cases were retrospectively analyzed. The male to female ratio was 2.4 to 1. The peak age incidence of urinary calculi occurred in the third decade. The ratio of upper urinary tract stones to lower urinary tract stones was 18 to 1. As to the laterality of the upper urinary tract stones, the ratio of left to right was 1.3 to 1. Analysis of the stone components revealed that the frequency ob calcium oxalate mixed with calcium phosphate and pure calcium oxalate was 80 percent and struvite, uric acid & cystinine were 14.1%, 2.6%, 1.6% respectively.

Adolescent↗
PubMed1986

Sequence of 2,617 nucleotides from the 3' end of Newcastle disease virus genome RNA and the predicted amino acid sequence of viral NP protein.

DNA fragments complementary to the Newcastle disease virus genome (strain D26) were cloned and sequenced. The sequence of 2,617 nucleotides from the 3' end of the genome was determined and an open reading frame (OP-1) consisting of 1,467 nucleotides, most likely encoding NP protein, was found in this region. This was followed by a second unfinished open reading frame (OP-2) of at least 729 nucleotides which continued beyond the 2,617th nucleotide. Another relatively short (312 nucleotides long) open reading frame (OP-2') was found overlapping with OP-2, but its significance is still unclear. The amino acid sequence deduced from the nucleotide sequence of OP-1 showed a moderate homology to that of the NP protein of Sendai virus in the central portion of the peptide. The leader sequence of 53 nucleotides was also identified. The 5' end of mRNAs synthesized in the infected cells was analyzed and found to be m7GpppA, suggesting that the transcription of viral mRNAs starts with A, but not with G residue.

Amino Acid Sequence↗