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Biomedical subjects

M Arai

Publications and source records attributed to M Arai.

At least 559 records · Page 31Linked to original sources
PubMed1987

Measurement of the alpha 2 component of a novel oncodevelopmental antigen by a rapid electroimmunoassay.

A method was required for the quantification of a novel oncodevelopmental antigen which increases in the serum of pregnant women as well as patients with ovarian cancer. The native antigen is composed of two components having alpha 2 and beta electrophoretic mobilities. An assay method, involving electroimmunodiffusion according to Laurell, was developed for the measurement of the alpha 2 component of the antigen. The method is sufficiently sensitive to determine significant differences in the levels of antigen in the serum of non-pregnant and pregnant subjects, and patients with ovarian cancer. In addition to routine quantitation, the technique will also be an indispensable analytical tool in the purification of the protein.

Antibody Specificity↗
PubMed1987

Self-catalyzed inactivation of cytochrome P-450 during microsomal metabolism of cannabidiol.

When cannabidiol (CBD) was incubated with hepatic microsomes of mice in the presence of an NADPH-generating system, a significant decrease of cytochrome P-450 content was observed by measuring its carbon monoxide difference spectra. The decrease of cytochrome P-450 by CBD required NADPH and molecular oxygen. The effect was partially inhibited by SKF 525-A but not by various scavengers of active oxygen species, superoxide anion, hydroxyl radical and singlet oxygen. The incubation of CBD with hepatic microsomes did not affect total heme but decreased significantly free sulfhydryl contents in the microsomes. The derivatives of CBD modified in the resorcinol moiety, CBD-monomethyl- and dimethylethers, almost lost the effect on cytochrome P-450, whereas those modified in the terpene moiety, 8,9-dihydro- and 1,2,8,9-tetrahydro-CBDs exhibited some potency to inactivate cytochrome P-450. The inactivation of cytochrome P-450 by CBD and related compounds led to the inhibition of hepatic microsomal p-nitroanisole O-demethylase and aniline hydroxylase activities. These results suggest that the resorcinol moiety of CBD plays some role in the inactivation of cytochrome P-450 by the cannabinoid.

Animals↗
PubMed1987

Primary structure of Paim I, an alpha-amylase inhibitor from Streptomyces corchorushii, determined by the combination of Edman degradation and fast atom bombardment mass spectrometry.

Paim I, a protein alpha-amylase inhibitor, inhibits animal alpha-amylases from pig, dog, cow, horse, etc. but has no activity against human salivary and pancreatic amylases. The primary structure of Paim I has been determined by Edman degradation and fast atom bombardment mass spectrometry (FABMS). This protein is a single-chain polypeptide of 73 amino acid residues with a calculated molecular weight from the sequence data of 7415.3 (monoisotopic molecular weight) and 7420.2 (average molecular weight). The sequencing strategy chosen for Paim I consists of four steps. First, the accurate molecular weights of the intact and tetra-S-carboxymethylated Paim I are determined by fast atom bombardment mass spectrometry. Second, the primary fragments generated by Staphylococcus aureus V8 protease are isolated by reversed-phase high-performance liquid chromatography. The molecular weights of these subpeptides are determined by FABMS. The peptides that must be sequenced are selected by the molecular weights of these subpeptides and the tetra-S-carboxymethylated Paim I. Third, these subpeptides and the whole protein are sequenced by automated Edman degradation. Finally, the primary structure of tetra-S-carboxymethylated Paim I is confirmed by the combination of tryptic, chymotryptic, and S. aureus V8 protease digestion and FABMS. The sequence of Paim I is compared with those of Haim II, Hoe-467A, Z-2685, and AI-3688 because they have different alpha-amylase inhibition spectra against mammalian alpha-amylases but belong to a family of related proteins.

Amino Acid Sequence↗
PubMed1987

Neurotensin receptors on the rat liver plasma membranes.

Neurotensin (NT) is now classified as a brain-gut peptide in the central nervous system and gastrointestinal tract. In the present study, we characterized the NT receptors on the rat liver plasma membranes. The specific binding of [3H]NT was time dependent, reversible, and saturable. Scatchard analysis of the specific binding data yielded two classes of binding sites, a high affinity site and a low affinity site. The average maximum number of binding sites (Bmax) amounted to 13.3 +/- 1.1 fmol/mg protein at high affinity site and 122.3 +/- 21.5 fmol/mg protein at low affinity site, respectively. The dissociation constant (Kd) had values of 0.39 +/- 0.01 nM at high affinity site and 8.1 +/- 1.1 nM at low affinity site, respectively. The amount of specifically bound [3H]NT was significantly reduced in the presence of mono and divalent cations, EDTA, EGTA and a peptidase inhibitor bacitracin, NT1-13 competed with [3H]NT for its binding site with an IC50 of 0.19 nM at high affinity site (0.2 nM concentration of [3H]NT) and 0.7 nM at low affinity site (4.0 nM concentration of [3H]NT). Xenopsin, a NT analogue separated from the skin of Xenopus laevis, was equipotent (IC50 0.75 nM) with NT1-13 at 4.0 nM concentration of [3H]NT. C-terminal sequence of NT contains the structure necessary for interaction with NT binding sites whereas N-terminal sequence had no binding activity. Since NT has a hyperglysemic and a hypercholesterolemic effects in rats, these NT receptors on the rat liver plasma membranes may be involved in the hyperglycemia and/or hypercholesteroremia induced by NT.

Amino Acid Sequence↗
PubMed1987

Murine monoclonal antibodies to the myelin-associated glycoprotein (MAG) recognize Leu-7-reactive molecules on human mononuclear cells.

It is known that the antibody to human myelin-associated glycoprotein (MAG) reacts with a subset of human mononuclear cells (MNC) mediating a natural killer (NK) activity. The properties of the target molecule of the anti-MAG antibody, however, have not yet been elucidated. Three (GC-J4, MC-P2, and MC-P4) of five murine monoclonal antibodies (mAb) to MAG bound to human MNC. Moreover, MC-P2 and MC-P4 inhibited the binding of 125I-labeled anti-Leu-7 to MNC in a dose-dependent fashion. Conversely, anti-Leu-7 inhibited the binding of MC-P2 and MC-P4 to MNC, but did not inhibit the binding of GC-J4. Therefore, it is possible that MC-P2 and MC-P4 bind directly to or close to the Leu-7 epitope, and that GC-J4 binds to the epitope which is distinct from the Leu-7 epitope. The electrophoretic patterns of immunoprecipitates with GC-J4, MC-P2 and anti-Leu-7 from detergent lysates of surface-labeled human MNC were very similar. The target molecules of anti-Leu-7 and anti-MAG mAb have apparent m.w. of 205, 170, 150, 135, 110, 85, 65, and 55 kDa. All of the molecules precipitated by these mAb are monomeric or noncovalently associated proteins, because the electrophoretic mobilities of the proteins remained unchanged whether the samples were reduced or not. MC-P4 may have a higher affinity for the 65 kDa molecule than the other mAb, and precipitates the 58 kDa molecule as well. Therefore, the fine antigenic specificity of MC-P4 is slightly different from those of anti-Leu-7 or MC-P2. The implication of these results is that mAb, whose specificity is directed to the carbohydrate part of human MAG, reacts with the Leu-7 reactive molecules on human MNC, and that at least two epitopes detected by anti-MAG mAb coexist on the surface molecules with various apparent m.w.

Animals↗
PubMed1987

Neurotensin-like immunoreactivity (NTLI) concentration in the cerebrospinal fluid of children and its alteration in a febrile aseptic meningitis.

Neurotensin-like immunoreactivity (NTLI) concentrations in the cerebrospinal fluid (CSF) of normal children and patients with febrile aseptic meningitis, aged 7 months to 15 years, were studied. The NTLI concentrations in CSF of 27 children with normal CSF findings were 160.1 +/- 54.6 pg/ml (mean +/- S.D.). The NTLI concentration in CSF of 26 patients in an acute phase of aseptic meningitis was 110.6 +/- 51.1 pg/ml which was significantly (P less than 0.01) lower than the controls. These patients had a mean temperature of 101.4 +/- 1.5 degrees F which remained elevated for an average of 3.5 days. The NTLI concentrations in CSF of 23 patients in a recovery phase (after blood and CSF findings became normal with no fever) were 166.5 +/- 57.8 pg/ml, which did not differ significantly from the normal. There were no statistical correlations between the NTLI concentration in CSF and the protein concentration or total cell count in CSF. These results suggest that NTLI concentration changes during a febrile aseptic meningitis and that it may be associated with thermoregulation.

Adolescent↗
PubMed1987

A case of "myopathy with tubular aggregates" with increased muscle fibre sensitivity to caffeine.

A 23-year-old man with "myopathy with tubular aggregates" had suffered from exercise-induced muscle cramps for 1 year. His general and neurological findings were normal. Laboratory investigations were within normal limits except for a slightly elevated serum creatine kinase level. Muscle biopsy showed some small angular fibres and scattered type 2B fibres with prominent tubular aggregates originating from the sarcoplasmic reticulum. Since the muscle fibres contracted at a lower concentration of caffeine, increased muscle fibre sensitivity to caffeine is probably related to muscle cramps in this disorder. Tubular aggregates are then secondarily formed in the muscle fibres.

Adult↗
PubMed1987

An ovarian cancer-associated antigen that crossreacts with a pregnancy-associated protein.

The presence of an ovarian ascitic antigen that crossreacts with a placental antigen was demonstrated in ascitic fluid from patients with advanced ovarian cancer, and the antigen was partially purified. Immunodiffusion and immunoelectrophoresis were employed to confirm the existence of the reactive antigen and to determine the relationships between the antigens from various sources. On double immunodiffusion, the ovarian ascitic antigen was found to be immunologically completely identical with a placental antigen against monospecific antisera raised against an ovarian ascitic and a placental antigen, respectively. On gel filtration on Sephadex G-200, the antigenic activity was eluted in two regions corresponding to different molecular sizes. The two preparations of the larger and smaller forms showed complete identity on double immunodiffusion, but dissimilar mobilities on immunoelectrophoresis. Preliminary characterization of the antigen revealed that it is distinct from several cancer-related antigens so far described.

Antigens, Neoplasm↗
PubMed1987

Interaction of insulin-like growth factor I with porcine thyroid cells cultured in monolayer.

The interaction of insulin-like growth factor I (IGF-I) with porcine thyroid cells cultured in monolayer was studied. Specific binding of [125I]iodo-IGF-I to thyroid cells was a reversible process dependent on the time and temperature of incubation. A steady state was achieved in 18 h at 4 C and averaged 14.2 +/- 2% (mean +/- SD)/10(6) cells. Binding of [125I]iodo-IGF-I was inhibited by unlabeled IGF-I; half-maximal inhibition occurred at concentrations of 2-5 ng/ml. Multiplication-stimulating activity (rat IGF-II) and pork insulin had relative potencies of 1:20 and 1:300 compared with IGF-I. Scatchard analysis of binding data revealed a single class of IGF-I receptors with a Ka of 4.3 X 10(10) M-1, 49,000 binding sites were estimated per cell. Affinity cross-linking and autoradiography demonstrated the presence of type I IGF receptors. Thyroid cells also had specific receptors for insulin, but specific binding of [125I]iodoinsulin (2.03 +/- 0.03%/10(6) cells) was much lower than that of [125I]iodo-IGF-I. Preincubation of thyroid cells with IGF-I or insulin caused a concentration-dependent decrease in [125I]iodo-IGF-I binding due to an apparent loss of receptors. Preincubation with epidermal growth factor, fibroblast growth factor, platelet-derived growth factor, or TSH did not alter subsequent binding of [125I]iodo-IGF-I. Low concentrations of IGF-I stimulated DNA synthesis and proliferation of thyroid cells and acted synergistically with epidermal growth factor. Multiplication-stimulating activity and insulin had relative potencies in stimulating DNA synthesis comparable to their abilities to inhibit the binding of [125I]iodo-IGF-I to thyroid cells, suggesting that their effects are mediated primarily by IGF-I receptors. Preincubation with IGF-I did not alter cAMP responsiveness to TSH. We, thus, demonstrated the presence of functional and regulated IGF-I receptors on porcine thyroid cells.

Animals↗
PubMed1987

In vivo effects of tetrahydrocannabinols and their eight monooxygenated metabolites of the hepatic microsomal drug-metabolizing enzyme systems of mice.

In vivo effects of tetrahydrocannabinols (THCs) and their eight monooxygenated metabolites on the hepatic microsomal drug-metabolizing enzymes in mice were studied. delta 8-THC and its metabolites (7 alpha-hydroxy-, 7 beta-hydroxy- and 7-oxo-delta 8-THC, and 8 alpha, 9 alpha- and 8 beta, 9 beta-epoxyhexahydrocannabinol) tended to increase the enzyme contents or activities except for 7 beta-hydroxy-delta 8-THC which affected the microsomal enzymes in a different manner between the single and subchronic treatments. Single administration (5 mg/kg, i.v.) of 7-oxo-delta 8-THC, 8 alpha, 9 alpha- and 8 beta, 9 beta-epoxyhexahydrocannabinol led to the significant increase in hepatic microsomal p-nitroanisole O-demethylase and aniline hydroxylase activities accompanying a significant increase in cytochrome P-450 content in hepatic microsomes. The same results were obtained with subchronic treatment of mice with these metabolites (5 mg/kg/d, i.v. for 7 d), although the effect of 8 beta, 9 beta-epoxyhexahydrocannabinol on cytochrome P-450 was not statistically significant. 7 beta-Hydroxy-delta 8-THC significantly increased nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductase and aniline hydroxylase activities by single administration, while the metabolite significantly decreased the contents of cytochrome b5 and P-450 and p-nitrophenol uridine diphosphate-glucuronyltransferase activity by the subchronic treatment. In contrast, delta 9-THC and its metabolites (8 alpha-hydroxy-, 8 beta-hydroxy- and 8-oxo-delta 9-THC) did not significantly affect the microsomal enzymes by both treatments except that the single administration of 8 alpha-hydroxy-delta 9-THC and the subchronic treatment of delta 9-THC significantly decreased NADPH-cytochrome c reductase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Biological activities of human growth hormone and its derivatives estimated by measuring DNA synthesis in Nb2 node rat lymphoma cells.

Nb2 cell is a rat lymphoma cell line that responds to lactogens such as prolactin and human growth hormone (hGH) with an increased rate of proliferation. We explored the relationship between the biochemical events induced by hGH and its derivatives and their receptor binding activities. hGH stimulated RNA, DNA and protein synthesis of Nb2 cells as a function of time. Stimulation of RNA and protein was maximal at 2-3 h and 12 h, respectively, after the addition of hGH. DNA synthesis, measured by the rate of [3H]thymidine incorporation, reached a maximum after 18-h incubation with hGH. Stimulation of DNA synthesis was elicited by hGH in a dose-dependent manner between 0.45 and 45 pmol/l. The activity of the 20 K hGH variant in stimulating DNA synthesis was approx 30% of that of hGH. In contrast, S1-hGH, which lacks a sequence of ten amino acids (140-149) of hGH, showed a 3.2-fold greater activity than hGH. F1 (amino-terminal sequence 1-134 of hGH) was only 0.06% as active as hGH, and the activity of F2 (C-terminal 42 amino acid residue of hGH) was less than 0.01%. Both fragment 1-15 and 32-46 were without effect. The relative potencies of these hGH derivatives in stimulating DNA synthesis were similar to their relative abilities to inhibit [125I]hGH binding to lactogenic receptors on Nb2 cell. Nb2 cells provide a suitable model to study the relationship between receptor binding and the biochemical events induced by lactogens.

Animals↗