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Biomedical subjects

T Kodama

Publications and source records attributed to T Kodama.

At least 685 records · Page 38Linked to original sources
PubMed1990

Effect of endoscopic sclerotherapy and propranolol on the blood flow of esophageal varices.

The blood flow in esophageal varices was measured by endoscopic laser Doppler velocimetry (LDV) in 27 patients histologically or clinically diagnosed as having liver cirrhosis. The effect of endoscopic injection sclerotherapy (EIS), and of intravenous oral administration of propranolol, on the output signal of LDV was evaluated. EIS was performed intravariceally after the measurement, with a 50% glucose solution, human thrombin (1000 U), and Aethoxysclerol as sclerosants.

Adult↗
PubMed1989

Thermostability of cytochrome c-552 from the thermophilic hydrogen-oxidizing bacterium Hydrogenobacter thermophilus.

The denaturation of the c-type cytochrome of the thermophilic bacterium Hydrogenobacter thermophilus cytochrome c-552 by heat and guanidine hydrochloride was studied by measuring the change in circular dichroic spectra. The melting temperature (T1/2) of cytochrome c-552 in the presence of 1.5 M guanidine hydrochloride was 34 degrees C higher than that of the c-type cytochrome of Pseudomonas aeruginosa cytochrome c-551. Hydrogenobacter cytochrome c-552 is a much more stable protein than cytochrome c-551 of the mesophilic bacterium P. aeruginosa, even though their amino acid sequences are 56% identical and they have numerous other similarities. However, notwithstanding these similarities between the sequences of the cytochromes c-552 and c-551 that were compared, it is very likely that these differences in stability could be due to some heretofore undefined differences in their spatial structures. It has been suggested that alpha-helix structure and electrostatic interaction could be the source of the stable spatial structure of cytochrome c-552.

Amino Acid Sequence↗
PubMed1989

[Changes in hepatic circulation after hepatic arterial embolization--an analysis of factors affecting the development of collaterals].

Forty six patients with follow up angiography after hepatic arterial embolization using gelatin sponge particles were analysed to evaluate the factors affecting development of intra- and extrahepatic collaterals. Significant correlation was demonstrated between the grade of embolization and the development of collaterals (p less than 0.001). Also there was significant correlation between development of collaterals and combined use of anticancer drugs with emboli (p less than 0.001). This suggests the possibility of endothelial damages of the arteries caused by anticancer drugs, which may enhance the permanent arterial occlusion and subsequent development of collaterals. No significant correlation was demonstrated between the numbers of embolization therapy and development of collaterals in this study.

Adult↗
PubMed1989

Slow fluctuations of single unit activities of hippocampal and thalamic neurons in cats. I. Relation to natural sleep and alert states.

Spontaneous unit discharges during the natural sleep-wakefulness cycle in two different neuronal groups, the hippocampal pyramidal cells and thalamic ventrobasal neurons, have been analyzed. The results show that both neurons fire with white-noise-like fluctuations during the slow-wave sleep, and with slow fluctuations with power spectral densities inversely proportional to the frequency in the frequency range of 0.02-1.0 Hz, during the paradoxical sleep. This confirms that the characteristics of fluctuations in neuronal activities of the mesencephalic reticular formation observed in our previous study are more general phenomena in the cat's brain. Partly similar behavior of spectral densities is also observed during the alert state. These observations are quantitatively confirmed by the statistical time series analysis of the spike density processes of spontaneous activities.

Action Potentials↗
PubMed1989

Slow fluctuations of single unit activities of hippocampal and thalamic neurons in cats. II. Role of serotonin on the stability of neuronal activities.

A series of experiments was carried out both in the hippocampal pyramidal and thalamic ventrobasal neurons to investigate the effect of serotonin level in the brain on slow fluctuations of neuronal discharges. Single neuronal activities were recorded in the following two pharmacologically treated states: (1) a 5-hydroxytryptamine depleted state by p-chlorophenylalanine administration (PCPA phase) and (2) a 5-methoxy-N,N-dimethyltryptamine administered state under the PCPA pretreatment (5-MeODMT phase). The slow fluctuations of neuronal activities in the frequency range of 0.02-1.0 Hz in both nuclei were prominent during the PCPA phase and were similar to those during the paradoxical sleep. In contrast, slow fluctuations were suppressed during the 5-MeODMT phase and neuronal activities during this phase were similar to those during slow wave sleep (SWS). The results show that serotonin in the brain definitely plays a role in stabilizing single neuronal activities.

Action Potentials↗
PubMed1989

Thickness of Brunner's glands and its clinical significance in peptic ulcer diseases.

The thickness of Brunner's glands was measured using an ocular micrometer in 297 cases of surgically resected peptic ulcer and in 120 autopsy cases (control group). The mean maximum thickness of Brunner's glands in the control group was 1.55 +/- 0.37mm (mean +/- SD) and no difference in thickness was noted for each decade of age. The mean maximum thickness of Brunner's glands in patients with gastric ulcer, duodenal ulcer and gastroduodenal ulcer was 2.34 +/- 1.06, 3.18 +/- 1.07 and 3.24 +/- 1.05mm, respectively. When an ulcer is within the duodenum, Brunner's glands near the ulcer were thicker than those contralateral to it. In patients with gastric ulcer, Brunner's glands were the thickest in the pyloric ulcer group and negative correlation was noted between the thickness of Brunner's glands and the distance to the ulcer from the pyloric ring. Since gastric acidity is supposed to be lower when an ulcer is located more proximally, these results suggest that Brunner's glands become hyperplastic not only with the presence of an ulcer in the duodenum but also by acid hypersecretion of the stomach.

Adult↗
PubMed1989

A case of endoscopic injection sclerotherapy for a bleeding duodenal varix.

A case of bleeding duodenal varix which was treated successfully with endoscopic injection sclerotherapy (EIS) is reported. The patient developed a hemorrhage from a varix in the descending portion of the duodenum two months after EIS for esophageal varices, and hemostasis was achieved using EIS with an intravericeal injection of 1% polidocanol. The duodenal varix decreased in size after EIS. Two months after EIS, a splenectomy was performed. During a 14-month follow up period after the EIS for the duodenal varix, there was no recurrent bleeding.

Adult↗
PubMed1989

Interspecies homology of cytochrome P-450: toxicological significance of cytochrome P-450 cross-reactive with anti-rat P-448-H antibodies in liver microsomes from dogs, monkeys and humans.

The mutagenic activation of various promutagens by liver microsomes from dogs, monkeys and humans was investigated. Dog liver microsomes efficiently catalyzed the mutagenic activation of Trp-P-2 and Glu-P-1 followed by IQ and AAF. Monkey liver microsomes were most active in the activation of IQ followed by Glu-P-1, AAF and Trp-P-2. Although there were remarkable individual differences, human liver microsomes were found to be most active in the mutagenic activation of IQ followed by Trp-P-2, Glu-P-1 and AAF. Antibodies against rat P-448-H inhibited the mutagenic activation of Glu-P-1, Trp-P-2 and IQ in rat and dog liver microsomes, and Glu-P-1 and Trp-P-2 in monkey liver microsomes. The activation of Glu-P-1 and IQ in human liver microsomes was also strongly inhibited by anti-P-448-H antibodies. The amounts of cytochrome P-450 cross-reactive with anti-P-448-H antibodies in human liver microsomes highly correlated with the capacity to activate Glu-P-1, Trp-P-2 and IQ but not AAF.

2-Acetylaminofluorene↗
PubMed1989

Gastrocarcinogen N-methyl-N'-nitro-N-nitrosoguanidine is an antiandrogen.

The present study has investigated comparatively the in vivo effects of physiologic saline drink, N-methylN'-nitro-n-nitrosoguanidine (MNNG) drink, saline-MNNG drink and hydrocortisone treatment in terms of 1 functional parameter (daily liquid consumption) and 3 weight parameters (weights of whole body, forestomach and glandular stomach) using Swiss/ICR mice of both sexes. The results obtained are as follows: 1) The sole use of hydrocortisone treatment significantly increased daily water consumption in mice of both sexes. 2) The promoting effect of the hormone on liquid consumption was further accelerated by concomitant use of physiologic saline. There was no sex difference in the extent of drink increase, but the figure of male mice was more variable than that of female mice. 3) The introduction of the 3rd stressor MNNG significantly reduced the salt-hydrocortisone-linked acceleration of liquid consumption. The extent of MNNG suppression was more marked in male mice than in female mice. 4) The responses of the 3 weight parameters to hydrocortisone were found to be tissue- and sex-specific. The dynamic changes of the above 4 parameters under the influence of the 3 stressors are in agreement with the interpretation that androgen plays a positive role in the salt-hydrocortisone-linked acceleration of liquid consumption, and that MNNG reverses the drink increase by inhibiting the binding of androgen with its receptor.

Androgen Antagonists↗
PubMed1989

Interaction between N-methyl-N'-nitro-N-nitrosoguanidine and 2 steroid hormones in the glandular stomach of mouse. I. Acceleration of hydrocortisone turnover by use of a salt-rich diet and the carcinogen.

The present study has investigated the question of whether or not hydrocortisone as a gene regulator plays a role in the expression of carcinogenic and cocarcinogenic actions of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and NaCl at the gastric epithelium. The interaction of local hydrocortisone, MNNG and NaCl was studied in vitro and in vivo using Swiss/ICR mice of both sexes. MNNG inhibited specific hydrocortisone binding with the cytoplasmic receptor from the glandular stomach of mouse. The intake of both excess NaCl and MNNG induced an increase in hydrocortisone turnover in the glandular stomach of mouse. Likewise, administration of either excess NaCl or MNNG increased the activity of ornithine decarboxylase in the glandular stomach of mouse. Long-term use of a salt-rich diet and MNNG drink induced an irreversible reduction in water consumption without affecting NaCl consumption, a dissociation of the hydrocortisone effect. The aforementioned MNNG effect on water turnover was more marked in female than in male mice. It is suggested that NaCl and MNNG produce a state of corticosteroid stimulation and androgen depression at the glandular stomach epithelium of mouse--a reproduction of the hormonal markers of gastric cancer.

Animals↗
PubMed1989

Interaction between N-methyl-N'-nitro-N-nitrosoguanidine and 2 steroid hormones in the glandular stomach of mouse. II. Retardation of local dihydrotestosterone turnover by use of a rice-rich diet and the carcinogen.

We investigated the question of whether or not N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a gastrocarcinogen with a structural resemblance to the antiandrogenic gastrosuppressant cimetidine, had a similar antiandrogenic activity in the glandular stomach of mouse. Possible influence of a rice-rich diet on the interaction of androgen with the same tissue was also studied in relation to its gastrosuppressive effect. The results obtained were as follows: 1) excess MNNG non-competitively inhibited the specific binding of 3H-dihydrotestosterone (DHT) with the cytoplasmic receptor of the glandular stomach of mouse; 2) the MNNG intake slowed down local 3H-DHT turnover in the glandular stomach of mouse; 3) evidence was presented to indicate that MNNG action was antiandrogenic in nature; 4) a rice-rich diet, exerting a weight-decreasing influence on the glandular stomach, also slowed down the 3H-DHT turnover in the same tissue. It was indicated that both MNNG and a rice-rich diet produced a state of androgen depression in the glandular stomach of mouse by slowing down the turnover of local androgen and/or competing with local androgen for its receptor in the target tissue. The significance of the results was discussed in relation to the etiology of gastric cancer.

Animals↗
PubMed1989

Vaccine protection against simian immunodeficiency virus infection.

Rhesus monkeys were immunized by multiple inoculations with purified, disrupted, noninfectious simian immunodeficiency virus (SIV) in adjuvant. Immunized monkeys developed anti-SIV antibodies detectable by whole-virus ELISA and by immunoblot reactivity; these antibodies had weak neutralizing activity. One week after the last immunization, monkeys were challenged with 200-1000 animal infectious doses of uncloned, live SIV. The same strain of SIV that was used for vaccination was also used for challenge. Anamnestic antibody responses and SIV recovery from peripheral blood were used to evaluate infection following the live virus challenge; two of six vaccinated monkeys showed no evidence of infection following the live virus challenge. Transfusion of 10 ml of whole blood from these two into uninfected, naive rhesus monkeys did not result infection of the recipients, providing further support for the lack of infection in the two previously vaccinated animals. Four of four unvaccinated control monkeys inoculated with these doses of live SIV became infected and three of these died with AIDS 118-258 days after infection. Only one of the six vaccinated monkeys has died to date. In situ hybridization with lymph node biopsy specimens suggested that the virus load was much higher in control macaques than in vaccinated macaques. These results indicate that vaccination with inactivated whole virus can protect macaques against challenge with live SIV. Furthermore, they provide hope that vaccine protection against human AIDS virus infection may be possible.

Animals↗
PubMed1989

Prevalence of antibodies to SIV in baboons in their native habitat.

We have documented rare infection of baboons in their native habitat with simian immunodeficiency virus (SIV). Of 124 sera collected from yellow baboons in central Tanzania, two gave high readings by SIVagm ELISA (greater than 1.0) and moderate by SIVmac ELISA (0.5-1.0). These two sera gave strong reactions to the major SIVagm proteins, including gp130, by western blot analysis; their reactivity to SIVmac protein was considerably weaker. Similar testing of 155 sera from olive baboons of Ethiopia revealed no clearly positive sera. Thus, 2 of 279 baboon sera or 0.7% were positive for antibodies to SIV. The strong reactivity of the two positive yellow baboon sera with SIVagm proteins raises questions about whether these animals may have been infected by green monkeys in their native habitat; baboons occasionally prey upon and eat green monkeys. In addition to these two clearly positive samples, one olive baboon serum and one yellow baboon serum reacted only with major gag protein (p24-p26). Continued study of prevalence and diversity of SIV in primates will be important for understanding the history and evolution of primate lentiviruses and, it is hoped, the origins of viruses that cause AIDS in humans.

Animals↗
PubMed1989

Effects of atelocollagen on the wound healing reaction following palatal gingivectomy in rats.

Collagen membrane preparations have been manufactured with the aim of enhancing wound healing following periodontal surgery. After cross-linking by various processing methods (with ultraviolet radiation or hexamethylenediisocyanate) and to various extents, atelocollagen membranes were applied into dissection sites within palatal gingival tissue. Applied atelocollagen was histopathologically compared with applied lyophilized porcine dermis (LPD) and controls in rats, with regard to the time course of healing. The atelocollagen-applied group showed more satisfactory regeneration of the epithelium and connective tissue in an artificially created gingival defect than did the control group or the LPD-applied group. Epithelial downgrowth along the root surface was significantly suppressed by the use of atelocollagen. In addition, the post-operative inflammatory reaction and foreign body giant cell reaction subsided rapidly after surgery in the atelocollgen-applied group. Our results show that the use of atelocollagen membrane in periodontal wounds should be the method of choice.

Animals↗
PubMed1989

Amino acid sequence of cytochrome c-552 from a thermophilic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus.

The complete amino acid sequence of cytochrome c-552 from an extremely thermophilic hydrogen bacterium, Hydrogenobacter thermophilus TK-6 (IAM 12695), was determined. It is a single polypeptide chain of 80 residues, and its molecular weight, including heme, was calculated to be 7,599. The sequence of cytochrome c-552 from H. thermophilus TK-6 closely resembles that of cytochromes c-551 from Pseudomonas species. Moreover, the tertiary structure of Hydrogenobacter cytochrome c-552 is suggested to be similar to that of cytochrome c-551 from Pseudomonas aeruginosa. The sequence similarity between Hydrogenobacter cytochrome c-552 and that of other bacteria physiologically related to H. thermophilus is not high.

Amino Acid Sequence↗
PubMed1989

Purification and characterization of ATP:citrate lyase from Hydrogenobacter thermophilus TK-6.

ATP:citrate lyase [ATP citrate (pro-3S)-lyase; EC 4.1.3.8] was purified and characterized from the cells of Hydrogenobacter thermophilus, an aerobic, thermophilic, hydrogen-oxidizing bacterium which fixes carbon dioxide by a reductive carboxylic acid cycle. The enzyme was quite stable, even in the absence of sulfhydryl reagents. Optimum pH for reaction was 6.7 to 6.9, and optimum temperature was around 80 degrees C. The molecular weight of native enzyme was estimated to be 260,000 by gel filtration analysis, and that of a subunit was estimated to be 43,000 by sodium dodecyl sulfate-polyacrylamide gel analysis. Km values for reaction components were as follows: citrate, 6.25 mM; ATP, 650 microM; coenzyme A, 40.8 microM; and Mg2+, 8 mM. The enzyme showed citrate synthase activity in the presence of Mg2+, but the reaction rate was very low (less than 1/200 of the lyase activity).

Bacteria↗
PubMed1989

Significance of premature stop codons in env of simian immunodeficiency virus.

The location of the translational termination codon for the transmembrane protein (TMP) varies in three infectious molecular clones of simian immunodeficiency virus from macaques (SIVmac). The SIVmac251 and SIVmac142 infectious clones have premature stop signals that differ in location by one codon; transfection of these DNAs into human HUT-78 cells yielded virus with a truncated TMP (28 to 30 kilodaltons [kDa]). The SIVmac239 infectious clone does not have a premature stop codon in its TMP-coding region. Transfection of HUT-78 cells with this clone initially yielded virus with a full-length TMP (41 kDa). At 20 to 30 days posttransfection, SIVmac239 virus with a 41-kDa TMP gradually disappeared coincident with the emergence of a virus with a 28-kDa TMP. Virus production dramatically increased in parallel with the emergence of a virus with a 28-kDa TMP. Sequence analysis of viral DNAs from these cultures showed that premature stop codons arising by point mutation were responsible for the change in size of the TMP with time. A similar selective pressure for truncated forms of TMP was observed when the SIVmac239 clone was transfected into human peripheral blood lymphocytes (PBL). In contrast, no such selective pressure was observed in macaque PBL. When the SIVmac239 clone was transfected into macaque PBL and the resultant virus was serially passaged in macaque PBL, the virus replicated very well and maintained a 41-kDa TMP for 80 days in culture. Macaque monkeys were infected with SIVmac239 having a 28-kDa TMP; virus subsequently recovered from T4-enriched lymphocytes of peripheral blood showed only the 41-kDa form of TMP. These results indicate that the natural form of TMP in SIVmac is the full-length 41-kDa TMP, just as in human immunodeficiency virus type 1. Viruses with truncated forms of TMP appear to result from mutation and selection during propagation in unnatural human cells.

Amino Acid Sequence↗