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Biomedical subjects

K Imai

Publications and source records attributed to K Imai.

At least 973 records · Page 54Linked to original sources
PubMed1991

Precolumn fluorescence tagging reagent for carboxylic acids in high-performance liquid chromatography: 4-substituted-7-aminoalkylamino-2,1,3-benzoxadiazoles.

Four new 2,1,3-benzoxadiazole amine reagents having different functional groups at the 4- and 7-positions, [4-nitro-7-N-piperazino-2,1,3-benzoxadiazole (NBD-PZ), 4-(N,N-dimethylaminosulphonyl)-7-N-piperazino-2,1,3-benzoxad iazole (DBD-PZ), 4-(N,N-dimethylaminosulphonyl)-7-N-cadaverino-2,1,3-benzoxad iazole (DBD-CD) and ammonium 7-N-piperazino-2,1,3-benzoxadiazole-4-sulphonate (SBD-PZ)] were synthesized as fluorogenic tagging reagents for carboxylic acids in high-performance liquid chromatography. The reagents, except SBD-PZ, reacted with carboxylic acid at room temperature in the presence of activation agents to produce fluorescent adducts. The maximum wavelengths of arachidic acid tagged with DBD-PZ, DBD-CD and NBD-PZ were 569 nm (excitation, 440 nm), 561 nm (excitation, 437 nm) and 541 nm (excitation, 470 nm), respectively. Among various activation agents tested [diethyl phosphorocyanidate (DEPC), diphenyl phosphoroyl azide (DPPA), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-pyridine, 2.2'-dipyridyl disulphide-triphenylphosphine (Mukaiyama A) and 2-chloro-1-methylpyridinium iodide-triethylamine (Mukaiyama B)], DEPC and Mukaiyama A were more effective than the others. When the piperazino reagents (DBD-PZ and NBD-PZ) were used as the tagging reagents, the derivatization reaction in the presence of Mukaiyama A was faster than that in the presence of DEPC. Although the reaction in the presence of Mukaiyama A was completed after 30 min, an unknown peak derived from the activation agent appeared on the chromatograms. The fluorescence peak intensities were compared in the presence of DEPC. The order of the fluorescence peak areas obtained after reaction for 6 h in the presence of DEPC was DBD-PZ greater than DBD-CD greater than NBD-PZ. Thirteen saturated free fatty acids (FFAs) derivatized with DBD-PZ (or DBD-CD) and DEPC (or Mukaiyama A) in acetonitrile were separated completely by linear gradient elution on a reversed-phase ODS column. Eight drugs (ibuprofen, indomethacin, dinoprost, prostaglandin E1, dehydrocholic acid, ursodesoxycholic acid, hydrocartisone succinate and prednisolone succinate) were also tagged with DBD-PZ in the presence of DEPC and separated by isocratic elution. The detection limits (signal-to-noise ratio = 3) of FFAs tagged with DBD-PZ were in the range 3.2-4.7 fmol, whereas those of drugs were in the range 3.9-14 fmol.

Anti-Inflammatory Agents↗
PubMed1991

[The effects of anti-androgen TZP4238 (17 alpha-acetoxy-6-chloro-2-oxapregna-4,6-diene-3,20-dione) and its related compounds on the in vitro formation of androgen-receptor complex].

It was reported that a new steroidal anti-androgen, TZP4238 (17 alpha-acetoxy-6-chloro-2-oxapregna-4,6-diene-3,20-dione), was 10 times stronger than chlormadinone acetate (CMA) as the in vivo anti-androgenic potential. To confirm this result, the effect of TZP4238 and CMA on ventral prostates of intact rats, or castrated ones treated by testosterone, was investigated. Our experiments demonstrated that TZP4238 was 3-5 times stronger than CMA. The effects of this compound on the androgen-receptor complex formation in the human and rat prostates were investigated and compared to the other anti-androgen and related compounds. An aliquot of cytosol or KCl extract from rat or human prostate was incubated with [3H]R1881 in the presence of various tested compounds. By means of dextran coated charcoal assay and sucrose density gradient centrifugation analysis, TZP4238 and TZP4239 showed a stronger inhibitory effect than other compounds except dihydrotestosterone. Judging from all these results, it was estimated that TZP4238 was 2-3 times stronger than CMA. The Scatchard plot analysis revealed that the inhibitory effect of TZP4238 was a competitive type. Between CMA and TZP4238, the difference of in vivo anti-androgenic potential was not identical with that of the inhibitory effect on the androgen-receptor complex formation.

Androgen Antagonists↗
PubMed1991

Genetic susceptibility to squamous cell carcinoma of the lung in relation to cigarette smoking dose.

Cytochrome P450IA1 is responsible for the metabolic activation of benzo(a)pyrene in cigarette smoke; an association of lung cancer with DNA polymorphisms of P450IA1 gene was shown in our previous study. In this paper, we investigated the interindividual difference of genetically determined susceptibility to squamous cell carcinoma of the lung in relation to cigarette smoking dose. We first compared the total amounts of cigarettes consumed over the lifetime of patients and showed that the patients with a "susceptible" P450IA1 gene genotype contracted carcinoma after fewer cigarettes [mean +/- SD, 31.3 +/- 12.8 x 10(4) cigarettes (n = 12)] than those with other genotypes [42.5 +/- 18.2 x 10(4) (n = 33)], with a statistical significance of P less than 0.05. Next, we carried out a case-control study to estimate the odds ratios of susceptible to nonsusceptible individuals in relation to the cumulated cigarette dose. We thus showed that the individuals with the susceptible genotype were at remarkably high risk with an odds ratio of 7.31 (95% confidence interval, 2.13 to 25.12) at a low dose level of cigarette smoking and that the difference in susceptibility between genotypes was reduced at high dose levels.

Adenocarcinoma↗
PubMed1991

Dominant expression of a distinctive V14+ T-cell antigen receptor alpha chain in mice.

A distinctive variable region 14-positive (V14+) alpha chain (V alpha 14+) of the T-cell antigen receptor is predominantly expressed in multiple mouse subspecies. The V alpha 14 family has two members, V alpha 14.1 and V alpha 14.2, which differ by only three amino acids at positions 50-52. Based on the EcoRI restriction fragment length polymorphism of the gene encoding V alpha 14, mice can be divided into three groups: type I with an 11.2-kilobase (kb) fragment, type II with a 2.0-kb fragment, and type III with the 2.0-kb and 11.2-kb fragments. Usage of V alpha 14-J alpha 281, where J alpha 281 is an alpha-chain joining segment, with a one-base N region dominates at the level of 0.02-1.5% of alpha chains in all laboratory strains, Mus musculus castaneus, and Mus musculus domesticus but not in Mus musculus molossinus, Mus musculus musculus, and Mus spicilegus samples. The preferential V alpha 14-J alpha 281 expression seems to be due to positive selection because the V-J junctional region is always glycine, despite the ability of the V alpha 14 gene to associate with J alpha other than J alpha 281. As V alpha 14-J alpha 281 expression is independent of known major histocompatibility complex antigens, including H-2, TLA, Qa, and HMT, the selecting ligand must be a monomorphic molecule of the mouse, expressed in a subspecies-specific manner. Additional observations, such as the expression of homogeneous V alpha 14-J alpha 281 in athymic mice, suggest that the positive selection of V alpha 14+ T cells occurs extrathymically.

Amino Acid Sequence↗
PubMed1991

Oxygen equilibrium properties of highly purified human adult hemoglobin cross-linked between 82 beta 1 and 82 beta 2 lysyl residues by bis(3,5-dibromosalicyl) fumarate.

We investigated oxygen equilibrium properties of highly purified human adult hemoglobin cross-linked between lysine-82 beta 1 and lysine-82 beta 2 by a fumaryl group, which is prepared by reaction of the CO form with bis(3,5-dibromosalicyl) fumarate. The cross-linked hemoglobin preparation isolated by the previous purification method, namely, gel filtration in the presence of 1 M MgCl2 followed by ion-exchange chromatography, was found to be contaminated with about 20% of an electrophoretically silent impurity that shows remarkably high affinity for oxygen. This impurity was separated from the desired cross-linked hemoglobin by a newly developed purification method, which utilizes a difference between the authentic hemoglobin and the impurity in reactivity of the sulfhydryl groups of cysteine-93 beta toward N-ethylmaleimide under a deoxygenated condition. After this purification procedure, the oxygen equilibrium properties of purified cross-linked hemoglobin in the absence of organic phosphate became very similar to those of unmodified hemoglobin with respect to oxygen affinity, cooperativity, and the alkaline Bohr effect. The functional similarity between the cross-linked hemoglobin and unmodified hemoglobin allows us to utilize this cross-linking for preparing asymmetric hybrid hemoglobin tetramers, which are particularly useful as intermediately liganded models. Previous studies on this type of cross-linked hemoglobin should be subject to reexamination due to the considerable amount of the impurity.

Adult↗
PubMed1991

Drug effects on CA125 antigen expression and antibody binding to cancer cells.

CA125 is a high-molecular weight glycoprotein expressed on most serous-type ovarian cancer and some lung adenocarcinoma tissues. The effects of various drugs on the release of CA125 antigen into culture medium and on monoclonal antibody (MAb) binding to cancer cells were studied using 8 human cancer cell lines, all of which expressed CA125 on their cell surfaces. The effect of dexamethasone was seen at as low a concentration as 10(-9) M dexamethasone, and the release of CA125 and the binding of radiolabelled anti-CA125 antibody were completely inhibited after exposure to 10(-7) M dexamethasone. The number of antibody binding sites markedly decreased. In contrast, sodium butyrate increased CA125 expression. These findings were clearly detected in only 3 cancer cell lines and a significant effect was not seen in the 5 other cancer cell lines. Interferon-gamma, examined in 3 cell lines, suppressed in a dose-dependent manner in 2 CA125 expression cell lines, but enhanced it in one line. No apparent effects were seen after exposure to tissue necrosis factor or interleukin-2. These results suggest that drugs may regulate the CA125 antigen expression in some, but not all, cancer cells and may affect the biodistribution of radiolabelled MAbs.

Antibodies, Monoclonal↗
PubMed1991

[Dependency of estramustine binding protein (EMBP) from rat prostate to endogenous androgen].

In this study, we investigated the dependency of estramustine binding protein (EMBP) from rat prostate on endogenous androgen. The EMBP content of the dorsolateral prostate markedly decreased 14 days after castration and increased again after the cessation of the weekly subcutaneous administration of 2 mg of Estradiol-17 beta valerate, in accordance with the recovery of prostate weight and serum testosterone concentration. This result clearly demonstrated that EMBP, which was present in very small quantities in the dorsolateral prostate, had a dependency on endogenous androgen as well as on the ventral prostate EMBP. We investigated the changes in prostate weights, EMBP concentration and serum testosterone level throughout life. The ventral prostate weight began to increase rapidly at 7 weeks of age and showed a broad peak from 11 to 14 weeks of age and then gradually decreased. On the other hand, the dorsolateral prostate weight began to increase rapidly at 7 weeks of age and continued to increase very gradually even after 10 weeks of age. There was a remarkable difference in the changes in EMBP concentration between the ventral prostate and the dorsolateral prostate. In the ventral prostate, EMBP concentration increased markedly from 4 to 9 week of age. Thereafter it continued to increase very gradually. On the other hand, in the case of the dorsolateral prostate, EMBP demonstrated higher and fluctuating concentration from 4 to 15 weeks of age. After 16 weeks of age, EMBP showed lower and stable concentration, although the weight of dorsolateral prostate showed gradual increase. These results suggested that there exist, beside androgens, some factors that participated in the regulation of growth and functional metabolism in the dorsolateral prostate after 16 weeks of age.

Animals↗
PubMed1991

Induction of antigen-specific immune response with use of anti-idiotypic monoclonal antibodies to anti-carcinoembryonic antigen antibodies.

Anti-idiotypic monoclonal antibodies (MoAbs) were prepared in a syngeneic system against anti-carcinoembryonic antigen (CEA) MoAb 5B3 (IgG1), which reacted with a carbohydrate moiety on CEA, and MoAb MA208 (IgG1), which reacted with a peptide on CEA. Anti-idiotypic MoAb T3-503 and T4-202 recognized the private idiotype of MoAb 5B3; anti-idiotypic MoAb M7-049 and M7-625 did so for MoAb MA208. Idiotype mapping showed that MoAb 5B3 has at least two distinct idiotopes at its combining site and MoAb MA208 also has two. Four different anti-idiotypic MoAbs (Ab2) could induce anti-anti-idiotypic antibodies (Ab3) specific to their respective immunizing anti-idiotypic MoAbs. Anti-anti-idiotypic MoAb M7-625 antiserum (at least a part of the antibodies) have the same reactivity as MoAb MA208, since the serum competed with the binding of MoAb MA208 against CEA and contained the antibody population reactive with purified CEA in immunoblotting assay. These results suggest that anti-idiotypic MoAb M7-625 bears the internal image of the antigen (CEA) and induces the anti-anti-idiotypic antibodies specific to CEA. Therefore, an anti-idiotypic antibody bearing the internal image of a tumor associated antigen might be used as a possible tool for vaccination or immunotherapy against malignant tumors as an antigen specific immunomodulator.

Animals↗
PubMed1991

Immunohistochemical and immunoelectron microscopical characterization of cerebrovascular and senile plaque amyloid in aged dogs' brains.

Immunohistochemical and immunoelectron microscopical studies were carried out on 28 aged dogs' brains. Amyloid deposits were seen in the arteries and capillaries in the leptomeninges and in superficial areas of the cortices in 19 (67.9%) of the 28 dogs (10-22 years of age). Immunohistochemically, these amyloid deposits were reactive for anti-beta/A4 antibody. Additionally, a variable number of parenchymal deposits with diffuse beta/A4-immunoreactivity (diffuse plaques) was also noted throughout the cerebral cortex in 24/28 dogs (85.7%). However, these plaque lesions were undetectable in Congo red staining. Electron microscopically, amyloid fibrils, measuring 10 nm in width, were located mainly in the tunica media of the arteries, and in less involved vessels they tended to be present among collagen fibres in the adventitia and smooth muscle cells in the outer layer of the media. The plaque lesions appeared to contain sparse aggregations of amyloid fibrils. In immunoelectron microscopical examinations, all amyloid fibrils in both blood vessels and plaques were selectively labelled by gold particles. These findings indicate that aged dogs can provide a useful experimental model for research into the beta/A4-type of cerebral amyloidosis commonly seen in Alzheimer's disease.

Aging↗
PubMed1991

Effect of radiation on the expression of carcinoembryonic antigen of human gastric adenocarcinoma cells.

The changes of antigenic expression of cultured human gastric adenocarcinoma MKN45 cells caused by irradiation were investigated to elucidate the immune responses to localized irradiation. The expression of carcinoembryonic antigen (CEA) showed remarkable increases in the culture supernatant and on the surface of the membrane of irradiated cells. The expression of major histocompatibility complex Class I antigen on the membrane also was enhanced by irradiation. In addition, the irradiated cell groups, when analyzed using a CEA-specific probe, showed remarkable increases in the CEA mRNA. These enhancements increased in the 10-Gy and 15-Gy irradiated populations compared with the 5-Gy irradiated population. These results suggest that the enhancement of expression of CEA by radiation takes place at the CEA gene expression (mRNA) level but not at the protein level.

Adenocarcinoma↗
PubMed1991

Conformational structure of a monoclonal anti-idiotypic antibody to the monoclonal anti-adenocarcinoma-associated carbohydrate antibody YH206.

The mAb AI206 (IgG1) is an anti-Id antibody of mAb YH206 (IgM) to adenocarcinoma-associated carbohydrate Ag and inhibits the reaction of mAb YH206 to YH206 Ag at low concentrations. By Western blot analysis, mAb AI206 only reacted with unreduced mAb YH206, whereas it did not react with reduced mAb YH206. Furthermore, mAb AI206 reacted with IgM subunit (180 kDa), F(ab')2 (110 kDa), and F(ab) (50 kDa) of pepsin-treated unreduced mAb YH206. Thus, mAb AI206 recognized the structure of F(ab) of mAb YH206. The mAb YH206 reacted with unreduced mAb AI206, F(ab')2 (110 kDa), and F(ab) (50 kDa) of pepsin-treated unreduced mAb AI206. It is presumed that mAb YH206 and mAb AI206 recognize each other in an unreduced condition but not a reduced condition. The recognition of such a conformational Id on F(ab) is important. Because mAb YH206 recognized the carbohydrate on YH206 Ag as well as the peptide on mAb AI206, the conformation on F(ab) of mAb AI206 may mimic the carbohydrate structure on YH206 Ag. In fact, YH206 antibody activity was induced in syngeneic mouse serum immunized with mAb AI206. These observations suggest that the internal image of YH206 carbohydrate Ag is preserved within the conformational Id on F(ab) of mAb AI206.

Adenocarcinoma↗
PubMed1991

Site-directed mutagenesis in haemoglobin. Functional role of tyrosine-42(C7) alpha at the alpha 1-beta 2 interface.

To clarify the functional role of Tyr-42(C7) alpha, which forms a hydrogen bond with Asp-99(G1) beta at the alpha 1-beta 2 interface of human deoxyhaemoglobin, we engineered two artificial mutant haemoglobins (Hb), in which Tyr-42 alpha was replaced by Phe (Hb Phe-42 alpha) or His (Hb His-42 alpha), and investigated their oxygen binding properties together with structural consequences of the mutations by using various spectroscopic probes. Like most of the natural Asp-99 beta mutants, Hb Phe-42 alpha showed a markedly increased oxygen affinity, a reduced Bohr effect and diminished co-operativity. Structural probes such as ultraviolet-region derivative and oxy-minus-deoxy difference spectra, resonance Raman scattering and proton nuclear magnetic resonance spectra indicate that, in Hb Phe-42 alpha, the deoxy T quaternary structure is highly destabilized and the strain imposed on the Fe-N epsilon (proximal His) bond is released, stabilizing the oxy tertiary structure. In contrast with Hb Phe-42 alpha, Hb His-42 alpha showed an intermediately impaired function and only moderate destabilization of the T-state, which can be explained by the formation of a new, weak hydrogen bond between His-42 alpha and Asp-99 beta. Spectroscopic data were consistent with this assumption. The present study proves that the hydrogen bond between Tyr-42 alpha and Asp-99 beta plays a key role in stabilizing the deoxy T structure and consequently in co-operative oxygen binding.

Hemoglobins↗
PubMed1991

Preparation and characterization of monoclonal antibodies specific to synthetic peptide of carcinoembryonic antigen.

Monoclonal antibodies (MAbs) were prepared to a synthetic peptide (PI: 119-140 amino acids) in domain 1 of the carcino-embryonic antigen (CEA) molecule. The majority of the amino acids in peptide PI show a hydrophilic character, and similar sequences are repeated in domains I, II and III of this molecule. These MAbs appear to recognize new epitopes of CEA, since representative conventional MAbs to CEA do not show reactivity to synthetic peptide PI. The resulting MAbs were divided into 2 groups; group 1 (MAb PI-706) reacted with peptide PI, but not with purified CEA preparation, while group 2 (MAb PI-234 and PI-255) reacted with either type of antigen, in the immunoblotting assay using purified CEA and in immunostaining of colonic carcinoma tissues. Furthermore, group-1 MAb PI-706 was reactive to purified CEA after treatment with periodate.

Amino Acid Sequence↗
PubMed1991

Sectional anatomy of the pelvis in the male rat with ultrasound correlations.

Ten-week-old male Wistar rats were used for sectional anatomy and ultrasonic diagnosis of the pelvis. The prostate and the urinary bladder were identified easily on longitudinal section by ultrasound examination. The prostate (ventral, lateral, and dorsal lobes) was located in the midline of the pelvis cavity on transverse sections and the caudal side of the urinary bladder on longitudinal sections. The urinary bladder was positioned at the cranial side of the prostate on longitudinal sections and in the midline of the pelvis cavity on transverse sections. The seminal vesicles were located at right and left positions of the urinary bladder. Ultrasonic diagnosis was estimated to be useful for experimental studies and we hope that ultrasound techniques may reduce the number of rats used for the treatment of prostate and urinary bladder cancers.

Animals↗
PubMed1991

4-(N,N-dimethylaminosulphonyl)-7-fluoro-2,1,3-benzoxadiazole as chemilumigenic reagent for high performance liquid chromatographic peroxyoxalate chemiluminescence detection.

4-(N,N-Dimethylaminosulphonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F), presented as a fluorogenic labelling reagent for amines and amino acids, is preferred for peroxyoxalate chemiluminescence (PO-CL) detection in high performance liquid chromatography. Amino acids and epinephrine derivatized with DBD-F were separated on a reversed phase column and detected at the femtomole level by the PO-CL detection system.

Amino Acids↗
PubMed1991

A new biodegradable copolymer of glycolic acid and lactones with relatively low molecular weight prepared by direct copolycondensation in the absence of catalysts.

Relatively low-molecular-weight copolyesters of glycolic acid (GA) with lactones such as gamma-butyrolactone (BL), delta-valerolactone (VL), and epsilon-caprolactone (CL) were synthesized by copolycondensation without catalysts. The resulting copolyesters are intended as carriers for drug delivery systems. Copolyesters with approximately 85 mol% GA (number-average molecular weight (Mn): 2900 +/- 100) are crystalline and solid and show a parabolic-type in vivo degradation pattern. The in vivo degradation of amorphous-pasty poly (GA/CL) (approximately 50/50 mol%) changed from parabolic-type to linear-type to S-type pattern as their molecular weight increased. A luteinizing hormone-releasing hormone agonist, [D-Leu6, des-Gly10]-LHRH ethylamide monoacetate (LHRH agonist), was incorporated into small cylinders with these copolyesters. An initial burst of LHRH agonist was observed for cylinders prepared with parabolic-type degrading copolyesters, in contrast to a marked delay in LHRH agonist release for cylinders prepared with S-type degrading copolyesters. The resulting daily dose of drug was maintained an approximately constant, though decreasing stepwise with time. For example, the daily amount of LHRH agonist released in vivo from a cylinder prepared with poly(GA/CL) (50/50 mol%; Mn = 4500) was 61 +/- 39 micrograms/day throughout an experimental period of 10 weeks with a corresponding pharmacological effect on the rat prostate.

Animals↗