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Biomedical subjects

K Imai

Publications and source records attributed to K Imai.

At least 1,441 records · Page 80Linked to original sources
PubMed1981

Distribution and molecular characterization of a cell-surface and a cytoplasmic antigen detectable in human melanoma cells with monoclonal antibodies.

The monoclonal antibodies 225.28S and 465.12 to human melanoma-associated antigens have been tested with a large variety of surgically removed skin lesions and malignant tumors as well as with a panel of cultured cell lines in serological and immunochemical assays. The antibody 225.28S reacts with a plasma membrane antigen while the antibody 465.12 detects a cytoplasmic antigen. Both antibodies fail to react with melanocytes from normal skin as well as benign skin lesions but react with nevi, melanoma cells and some skin carcinomas. Analysis with surgically removed tumors and cultured human cell lines indicated that the plasma membrane antigen is restricted to skin lesions whereas the cytoplasmic antigen is synthesized by tumor cells of various histological origins. The plasma membrane antigen is composed of two glyco-polypeptides of 280,000 and greater than 440,000 daltons, while the cytoplasmic antigen consists of 4 glycopolypeptides of 94,000, 75,000, 70,000 and 25,000 daltons. None of these components are bridged by disulfide bonds. The cytoplasmic antigen was readily detected in the spent culture medium of melanoma cell lines in the form of a major 94,000 dalton and a minor 72,000 dalton structure, while the plasma membrane antigen was detectable only after vastly increasing the sensitivity of the assay system.

Antibodies, Monoclonal↗
PubMed1981

Functional abnormalities of hemoglobin Toyoake (142 (H20)beta, Ala leads to Pro).

Oxygen equilibrium of Hb Toyoake (142 (H20)beta, Ala leads to Pro) is characterized by an oxygen affinity 6-times higher than that of Hb A, a slightly decreased alkaline Bohr effect, diminished cooperativity, with Hill's coefficient decreased by 1.2, and reduced response to 2,3-diphosphoglycerate and inositol hexaphosphate. These properties are in qualitative agreement with those shown previously from oxygen equilibrium data for hemolysate containing Hb Toyoake. The heat of oxygenation was -13.5 kcal/mol for Hb Toyoake and -12.9 kcal/mol for Hb A at pH 7.4 in 0.1 M Cl- and they became equal when corrected for the heat of oxygen-linked proton and Cl- release. OxyHb Toyoake autooxidized faster than oxyHb A. The visible absorption spectrum and electron paramagnetic resonance spectrum of oxidized Hb Toyake indicated that oxidation of this hemoglobin, either by autooxidation or by K3Fe(CN)6, is followed by gradual conversion into hemichrome derivatives. The soret peak of deoxyHb Toyoake was lowered compared to that of deoxyHb A and the magnitude of narrow-banded oxy-minus-deoxy difference spectrum around 290 nm was smaller for Hb Toyoake than for Hb A, indicating that the former remains predominantly in the R state upon deoxygenation. The functional abnormalities, including tendency to lose heme groups previously reported, were interpreted in terms of structural disturbance by proline at 142beta of 141 leucine, 143 histidine, 145 tyrosine, and 146 histidine residues of the same beta chain.

Diphosphoglyceric Acids↗
PubMed1981

Mechanism of retention of estramustine in the rat prostate and results of a clinical trial of Estracyt in Japan.

To clarify the mechanism of action of Estracyt, we performed experiments using 3H-estramustine of high specific activity. 3H-Radioactivity accumulated selectively in the ventral prostate of castrated male rats after the administration of 3H-estramustine. Estramustine and its metabolites were retained in the ventral prostate for long time periods. The uptake of 3H-radioactivity was almost totally localized in the cytosol fraction, but not in a purified receptor fraction. The apparent equilibrium dissociation constant of the estramustine binding protein was 18.9 nM, and the apparent equilibrium Bmax value was 0.76 nmoles/mg of cytosol protein. In addition, we wish to report in this paper the results of clinical trials of Estracyt studied by a cooperative research group in Japan from 1977 to 1979. It was concluded that Estracyt was effective in 89% of previously untreated prostatic cancer patients and in 38% of reactivated cancer patients.

Animals↗
PubMed1981

Effect of muramyldipeptide, a synthetic bacterial adjuvant, on enzyme release from cultured mouse macrophages.

Monolayer cultures of macrophages obtained by peritoneal lavage of normal or thioglycollate-stimulated mice spontaneously secreted lysosomal enzymes into the culture medium. When the elicited macrophages were cultured in the presence of muramyldipeptide (MDP), a 20-30% increase in the release of beta-glucuronidase was consistently observed and the intracellular activity decreased to about 45% of that of control cells after 6-8 days' culture. A stimulatory effect of MDP on lysozyme secretion, though less profound, was also observed. In contrast, release of neither enzyme was stimulated in resident macrophages by the addition of MDP. A neutral alpha-glucosidase, which has recently been found to localize also in granules of macrophages, remained inside the cells and neither its activity nor its release was affected by the addition of MDP to either type of macrophages. A large amount of lactic dehydrogenase was released only when the resident, not the elicited, macrophages were cultured for 3-4 days and then phagocytosed zymosan.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1981

ADCC of cultured human melanoma cells: analysis with monoclonal antibodies to human melanoma-associated antigens.

Four monoclonal antibodies to human melanoma-associated antigens (MAA) were found to be able to mediate specific cell-dependent lysis (ADCC) of cultured human melanoma cells. The extent of specific lysis of melanoma cells was influenced by the effector to target cell ratio, the amount of antibody added to the reaction mixture, and the incubation time. Cultured melanoma cells treated for 16 h with puromycin or cycloheximide (final concentration, 1.0 micrograms/ml) displayed increased susceptibility to ADCC even though the cell surface expression of MAA was not changed. On the other hand, treatment of melanoma cells with tunicamycin (final concentration, 1.0 microgram/ml) reduced the expression of MAA but did not affect susceptibility to ADCC. These findings suggest that other properties of the target cell membrane besides antigen density play a role in the outcome of ADCC reaction.

Antibodies, Monoclonal↗
PubMed1981

Properties of the lactose transport system in Klebsiella sp. strain CT-1.

Highly purified [D-glucose-1-14C]lactose has been used to study the transport of lactose by Klebsiella sp. strain CT-1. Strain CT-1 transports lactose by a lactose-inducible system that exhibited an apparent Km of 6 mM lactose and an apparent Vmax of 140 nmol/min per mg of cell protein. Lactose uptake was inhibited competitively by o-nitrophenyl-beta-D-galactoside with a Ki value of 8 mM, but was not inhibited by thio-beta-methyl-galactoside. D-Glucose, D-mannose, 2-deoxyglucose, and alpha-methyl-D-glucoside also inhibited lactose uptake. Phosphoenolpyruvate-dependent hydrolysis of o-nitrophenyl-beta-D-galactoside and lactose-dependent release of pyruvate from phosphoenolpyruvate by benzene-treated CT-1 cells showed that CT-1 transports lactose by a phosphoenolpyruvate:sugar phosphotransferase system. Correlations between the growth rate of CT-1 on lactose and properties of the transport system indicated that transport is the rate limiting step in utilization of lactose.

Biological Transport↗
PubMed1981

[Acute toxicological studies of captopril in rats and mice].

The acute toxicity of captopril, a potential inhibitor of angiotensin converting enzyme, was studied in Sprague-Dawley rats and ICR mice. In the oral administration, a decrease of spontaneous motor activity, lacrimation, salivation and decline of body temperature was noted in the rats and mice. In the mice, tarry stool was also noted. The LD50 was estimated as: 4249 mg/kg in male mice, 5050 mg/kg in female mice, 4336 mg/kg in male rats and 4245 mg/kg in female rats, In the dead animals, a hemorrhagic erosion or ulcer was recognized in the glandular stomach. An intravenous captopril in mice, caused immediate death by dyspnea in some animals within 3 minutes, but delayed death was also occurred within 24 hours showing a decrease of spontaneous motor activity and decline of body temperature. The LD50 was estimated as 3154 mg/kg in male mice and 3225 mg/kg in female mice. A single intravenous administration of captopril in dose of 1600 mg/kg did not cause any death in the rats of both sexes. The mice of both sexes well tolerated a single subcutaneous administration of captopril in a dose of 2400 mg/kg. No death occurred in rats of both sexes received subcutaneously captopril in a dose of 1200 mg/kg. At an injection site, a necrotic ulcer was noted in the skin of rats and mice which received subcutaneously captopril in a dose of 1600 mg/kg or more and 1200 mg/kg, respectively.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1981

[One month studies on the subacute toxicity of captopril in rats].

Subacute toxicity of captopril by daily oral administration at dose levels of 10 mg/kg, 30 mg/kg, 100 mg/kg, 300 mg/kg, 900 mg/kg and 2700 mg/kg for one month was studied in Sprague-Dawley rats. In the 2700 mg/kg group, 13 of 18 males and 17 of 18 females died with marked emaciation and abdominal distension. In the 900 mg/kg group, 1 of 18 males and 3 of 18 females died also during the administration period. In dead animals, a marked dilatation of gastrointestinal tract was noted showing multiple hemorrhagic erosions and/or ulcers in the glandular stomach. The remainder of these groups exhibited polydipsia and polyuria during the dosage period. In the 300 mg/kg and 100 mg/kg groups, all animals survived throughout the entire experimental period showing polydipsia and polyuria. In the 30 mg/kg and 10 mg/kg groups, all animals survived also throughout the entire dosage period without showing any toxic sign. Regarding plasma analysis, the BUN and creatinine concentration was significantly elevated in the group of 100 mg/kg or more. In the hematological examination, there was a decrease of erythrocyte counts, hemoglobin contents and hematocrit values in the group of 300 mg/kg or more. Pathological examinations revealed a marked thickening of the wall in afferent arterioles and interlobular arteries of the kidney in association with hypertrophy and hyperplasia of juxtaglomerular cells in 100 mg/kg, 300 mg/kg, 900 mg/kg and 2700 mg/kg groups. In these groups, multiple hemorrhagic erosions with or without ulcer were also noted in the glandular stomach. In the spleen, a slight increase of extramedullary hematopoiesis and hemosiderosis was noted in the 100 mg/kg, 300 mg/kg, 900 mg/kg and 2700 mg/kg groups, in which an increase of erythropoietic elements was also noted in the bone marrow. From these results, the maximum nontoxic dose was estimated as about 30 mg/kg/day by oral administration of captopril in the rats.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1981

[Twelve month studies on the chronic toxicity of captopril in rats].

The chronic administration of captopril to Sprague-Dawley rats was performed under the barrier system by feeding ad libitum with mixed diet in various concentrations of captopril with 3 months recovery period. The number of animals was 180 female and 180 male including 5 groups of control, 30, 100, 300 and 900 mg/kg/day. The maximum nontoxic dose was estimated as about 30 mg/kg/day for male but a little more than this for female rats. Body weight increase was significantly reduced in male but for the first 3 months in female rats. No death was ascribed to the toxic effect of captopril. Polydipsia and polyuria in male, and the significant increase in values of BUN and inorganic phosphate in both sexes were observed. The reduction in erythrocyte count, values of hemoglobin and hematocrit, hemosiderosis in reticulum cells of the spleen and Kupffer cells in the liver and the increase of erythropoieses indicated hemolytic anemia. Heart weight reduced while kidney weight increased. Pathological examination revealed hypertrophia and hyperplasia of JG cells and thickening of walls of afferent arterioles with hyperplasia of vascular smooth muscle cells and increase of collagen fibers. Thickening of walls extended to walls of the interlobular arteries which remained after withdrawal of captopril for 3 months though JG granules attenuated. The age-related increases of incidences of proteinuria and myocardial fibrosis were attenuated dose-dependently which are probably due to hypotension induced by captopril.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1981

[Three month subacute toxicity of captopril in beagle dogs].

Thirty four beagle dogs, male and female were orally given 10, 30, 100 and 200 mg/kg/day of captopril, an angiotensin converting enzyme inhibitor, for 3 months followed by a recovery test for 4 weeks. One of 4 female dogs which were treated with the highest dose of 200 mg/kg/day throughout the experimental period died of bronchial pneumonia. Hypersalivation and occasionally vomiting was observed in dogs treated with 100 and 200 mg/kg/day. Skin eruption such as erythema and papules was observed mostly at the ventral surface of the neck, chest and upper abdomen in dogs in these two experimental groups. Histological examination of the lesion revealed cellular infiltration with edema and expansion in the dermis and slight hyperkeratosis with parakeratosis and acanthosis. Changes in erythrocyte counts, hematocrit values and hemoglobin contents during the course of administration were variable among dogs but these were obvious in animals treated with higher doses. An increase in erythropoiesis of the bone marrow, extramedullary hematopoiesis and slight hemosiderosis in liver and spleen were revealed by histological examination. Above histological observations suggest that captopril may cause hemolysis. Hypertrophy and hyperplasia of juxtaglomerular cells with increased number of JG granules were shown in the highest dosage group even 4 weeks after suspension of captopril administration. A distinct plasma renin activity supported the morphological changes. From the results of three months administration of captopril to beagle dogs, the maximum non-toxic dose may be around 10 mg/kg/day and toxic dose 100 mg/kg/day.

Angiotensin-Converting Enzyme Inhibitors↗