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Biomedical subjects

H Seki

Publications and source records attributed to H Seki.

At least 307 records · Page 17Linked to original sources
PubMed1982

Induction of E-rosette-promoting factor in human plasma by levamisole: an assessment in a patient with partial DiGeorge syndrome.

A male infant with partial DiGeorge syndrome responded to weekly administration of levamisole (2.5 mg/kg of body weight) with an increase of circulating E-rosette-forming T cells. Thymic hormone activity in plasma appeared to be elevated to a near-normal level of 11.6 ng thymopoietin equivalent/ml after levamisole administration. The in vitro incubation studies indicated that levamisole by itself had no E-rosette-promoting ability, but a dialysable and relatively heat-stable plasma factor induced by levamisole both in the patient and in healthy individuals had E-rosette-promoting activity for the patient's lymphocytes. Such a plasma factor, however, could not be induced in all four thymectomized myasthenic subjects examined, suggesting a thymus-dependent nature of the plasma factor. These results suggest that levamisole might mediate an increased secretion of humoral factor(s) with E-rosette-promoting activity, even from such a rudimentary thymus as in the partial DiGeorge syndrome.

DiGeorge Syndrome↗
PubMed1982

Development of a new peroral cholangioscope (FDS-CP).

We have developed a new fibercholangioscope (FDS-CP), which is introduced into the common bile duct via the sphincterotomized papilla of Vater under the rope-way guidance of a balloon catheter. The scope was successfully inserted into the common bile duct in all 12 cases tried and was proved efficient for clinical use. The time required for introduction was 5 min on the average for a balloon catheter and 8 min for the scope to be introduced into common bile duct. The instrument has made it possible to perform precise observations and accurate biopsy of the common bile duct and parts of the main hepatic duct. It is also possible to perform therapeutical trials of removing stones located in the extrahepatic and intrahepatic bile ducts.

Adenocarcinoma↗
PubMed1981

The oxidation of ferrocytochrome c by Br2-, (SCN)2-, N3 and OH radicals studied by pulsed-electron and gamma-ray radiolysis.

The reactions of ferrocytochrome c with Br2-, (SCN)2-, N3 and OH radicals were followed by measuring the change in the optical spectra of cytochrome c on gamma-irradiation as well as the rate of change of absorbance upon pulse irradiation. Ferrocytochrome c is oxidized to ferricytochrome c by Br2-, (SCN)2- or N3 radical with an efficiency of about 100% through a second-order process in which no intermediates were observed. The rate constants in neutral solutions at I = 0.073 are 9.7 . 10(8) M-1 . s-1, 7.9 . 10(8) M-1, 1.3 . 10(9) M-1 . s-1 for the oxidation by Br2-, (SCN)2- and N3 radicals, respectively. The rate constants do not vary appreciably in alkaline solutions (pH 8.9). The ionic strength dependence was observed for the rate constants of the oxidation by br2- and (SCN)2-. Those rate constants estimated on the assumption that the radicals react only with the amino acid residues with the characteristic steric correction factors were less than one-tenth of the observed ones. These results suggest that the partially exposed region of the heme is the probable site of electron transfer from ferrocytochrome c to the radical. Hydroxyl radicals also oxidize ferrocytochrome c with a high rate constant (k greater than 1 . 10(10) M-1 . s-1), but with a very small efficiency (5%).

Animals↗
PubMed1981

Experimental hemorrhagic thalamic infarction in the dog.

As we have previously reported, a focus of cerebral infarction confined to the anterior half of the thalamus can be produced in the dog by simultaneously occluding four main arteries at the base of the brain. This knowledge was the basis of an investigation of hemorrhagic infarction following recirculation. In the animals after 6- to 12-hour occlusion, a high incidence of hemorrhagic infarction was found following recirculation. In brains autopsied 1 hour after recirculation, hemorrhagic infarction was seen in all of the dogs. The changes in regional cerebral blood flow and in computerized tomographic scans in this hemorrhagic infarction focus were also investigated.

Animals↗
PubMed1981

[Effect of mannitol on rCBF in canine thalamic ischemia-an experimental study (author's transl)].

We already reported in our experimental studies that mannitol acts to inhibit cerebral infarction. The purpose of this study was to investigate the efficacy of mannitol as assessed in terms of rCBF. The experiments were carried out with the thalamic infarction model in dogs, an experimental model developed and reported by us previously. The rCBF in the thalamus was measured by the initial slope method of hydrogen clearance curves. Following administration of 20% mannitol (2 g/kg) over a period of 10 minutes, slight increases in rCBF occurred during arterial occlusion. However the effect was more pronounced in mild than in severe ischemia. The length of time required for rCBF to return to its premedication level was almost 60 minutes.

Animals↗
PubMed1981

[Suppression of infarctic changes with mannitol and fluorochemicals--an experimental study].

We have developed and previously reported a canine model for diffuse, incomplete cerebral hemisphere infarction produced by simultaneously occluding the following 5 arteries unilaterally at the base of the brain: the A2 portion of the anterior cerebral artery, the A1 portion of the anterior cerebral artery at the bifurcation of the ethmoidal artery, the internal carotid artery, the posterior cerebral artery at the bifurcation of the posterior communicating artery and the anterior cerebellar artery. After 6 hours of occlusion, recirculation was allowed, and sequential observation was made on the degree of brain swelling. Investigation was made on whether or not administration of 20% mannitol or fluorocarbon emulsion (20% fluosol DA) following vascular occlusion is effective in suppressing such swelling. It was found that brain swelling could be prevented using by mannitol and fluorocarbon emulsion together, but not mannitol and fluorocarbon emulsion alone. Based on these results, we found that mannitol administered together with fluorocarbon emulsion has a protective effect for cerebral infarction following 6 hours vascular occlusion.

Animals↗
PubMed1981

Dimer formation in radiation-irradiated aqueous solution of lysozyme studied by light-scattering-intensity measurement.

The reaction of lysozyme with OH., Br.-2 and e-aq, produced in an aqueous solution by pulsed electrons and gamma-rays, were investigated. Irradiated enzymes showed an increase in the light scattering intensity (LSI) which is proportional to the absorbed dose. Results obtained from SDS gel electrophoresis confirm dimerization of lysozyme, which is considered to be responsible for the increase in LSI. It was found that the rate constant of the dimerization of protein radicals produced in the reaction with OH. is 2K=(1.0 +/- 0.3) X 10(6)M-1 s-1 and the yield of the dimerization is 0.6 in G. The enzymatic activity of the dimer is shown to be reduced to about 30 per cent of that of the intact enzyme. It is concluded that the radiation-induced inactivation of lysozyme is largely due to dimerization.

Electrons↗
PubMed1980

Acute lead poisoning of the pigeon induced by single, intraperitoneal administration of lead acetate.

A single dose of lead acetate (either 30 mg/kg or 150 mg/kg) was intraperitoneally (i.p.) administered to adult feral pigeons, Columba livia var and the effects of calcium disodium ethylenediamine tetraacetate (CaNa2EDTA), (0, 150, 300, 600 mg/kg), administered i.p. twice a week in the ensuing period were observed. Lead acetate caused dose related mortality and decreases in weight, hematocrit and delta-aminolevulinic acid dehydratase activity (ALA-D). Acute toxicity of lead acetate in the pigeon, when given intraperitoneally, appeared approximately equivalent to that in the rat and mouse in terms of LD50. Blood lead (blood Pb) levels observed during the lethal stage were five to ten times less than those reported for chronic oral lead poisoning in the pigeon. Biological implications of elevated levels of blood Pb observed in the feral pigeon in the urban Tokyo area are discussed. CaNa2EDTA induced dose related recovery in ALA-D in 30 mg/kg group, and reduction of blood Pb levels in the group dosed with 150 mg/kg of lead acetate.

Animals↗
PubMed1980

Recirculation in the acute period of cerebral infarction: experimental research on brain swelling and its suppression by using mannitol or glycerol.

Using our previously published "incomplete cerebral hemispheric infarction model in dogs" (produced by simultaneous ipsilateral occlusions of the anterior cerebral artery at the branching of the ethmoidal artery from its A1 portion, the A2 portion, the internal carotid artery, the posterior communication artery, the posterior cerebral artery, and the anterior cerebellar artery), two, four, or six hours occlusion of blood flow was undertaken. Observations were then made on the degree of brain swelling following recirculation due to administration of mannitol or glycerol solutions. Furthermore, the leakage of Evans blue was investigated to determine the damage to the blood brain barrier. 1. In the animals given mannitol or glycerol, brain swelling was suppressed, following two hours occlusion, In the animals given mannitol, however, brain swelling was not suppressed after four or six hours occlusion. 2. After two hours occlusion in the animals given mannitol, leakage of Evans blue was slight compared with the untreated group. In the six hours occlusion groups, severe leakage of Evans blue was seen in both the untreated animals and the mannitol-treated. After two hours occlusion, in some animals which had been given glycerol, severe leakage of Evans blue was seen, even when there was little brain swelling.

Animals↗