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Biomedical subjects

T Yamamura

Publications and source records attributed to T Yamamura.

At least 325 records · Page 18Linked to original sources

Radioimmunoassay of cholecystokinin in plasma.

A sensitive and specific radioimmunoassay for cholecystokinin (CCK) has been developed. Synthetic unsulfated carboxy-terminal fragment, CCK-8, was radioiodinated by the conventional Chloramine-T method. Antibodies were raised against sulfated CCK-8 covalently coupled to bovine thyroglobulin via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. By purification, highly immunoreactive 125I-labeled CCK-8 was obtained. The antiserum was highly avid, and plasma could be assayed directly. The detection limit of the assay was 5 pmol of sulfated CCK-8 per liter. The assay measured fragments CCK-8, CCK-33, and CCK-39 with equimolar potency. CCK-4, gastrin, and vasoactive intestinal polypeptide were not detected, even at higher concentrations. The concentration of CCK, as the sum of these CCK peptides, in plasma during fasting was low (10.5 +/- 2.1 pmol/L, mean +/- SEM) but still detectable in all normal subjects examined (range, 6.4-20.1 pmol/L). After ingestion of a test meal, CCK in plasma increased rapidly, peaking at 41.3 (SEM 5.7) pmol/L at 40 min and remaining high for 3 h after the meal. This supports the concept that CCK has important roles in digestion and absorption.

Adult↗

Multiple bidirectional alterations of phenotype and changes in proliferative potential during the in vitro and in vivo passage of clonal mast cell populations derived from mouse peritoneal mast cells.

Mouse peritoneal mast cells (PMC) express a connective tissue-type mast cell (CTMC) phenotype, including reactivity with the heparin-binding fluorescent dye berberine sulfate and incorporation of [35S] sulfate predominantly into heparin proteoglycans. When PMC purified to greater than 99% purity were cultured in methylcellulose with IL-3 and IL-4, approximately 25% of the PMC formed colonies, all of which contained both berberine sulfate-positive and berberine sulfate-negative mast cells. When these mast cells were transferred to suspension culture, they generated populations that were 100% berberine sulfate-negative, a characteristic similar to that of mucosal mast cells (MMC), and that synthesized predominantly chondroitin sulfate [35S] proteoglycans. When "MMC-like" cultured mast cells derived from WBB6F1-+/+ PMC were injected into the peritoneal cavities of mast cell-deficient WBB6F1-W/Wv mice, the adoptively transferred mast cell population became 100% berberine sulfate-positive. In methylcellulose culture, these "second generation PMC" formed clonal colonies containing both berberine sulfate-positive and berberine sulfate-negative cells, but exhibited significantly less proliferative ability than did normal +/+ PMC. Thus, clonal mast cell populations initially derived from single PMC exhibited multiple and bidirectional alterations between CTMC-like and MMC-like phenotypes. However, this process was associated with a progressive diminution of the mast cells' proliferative ability.

Animals↗

Immunohistochemical determination of immunosuppressive acidic protein in reactive and neoplastic diseases of macrophage.

Immunosuppressive acidic protein (IAP), a substance purified from cancer ascitic fluid, is released into the culture medium of macrophages and neutrophils, and is supposed to suppress an immune function of the host. Elevation of serum IAP in cancer patients has been reported. In the current study, presence of IAP in proliferating diseases of macrophage was examined. Macrophages in reactive proliferation, histiocytosis X, and neoplastic proliferation gave positive reaction for IAP. Diffuse cytoplasmic staining was usual, but dot-like or globular and surface staining also were observed. Proliferating cells in malignant fibrous histiocytoma were more sensitively stained by IAP than by other ordinary used markers for macrophage. These findings provide useful information to understand the mechanism of elevation of serum IAP in cancer patients.

Histiocytoma, Benign Fibrous↗

Immunosuppressive acidic protein in true histiocytic lymphoma.

Serum immunosuppressive acidic protein (IAP) was determined in patient with true histiocytic lymphoma. The change of serum level of IAP correlated well with the clinical course, i.e., increased at relapse and decreased during remission. Immunohistochemistry showed IAP was present in the cytoplasms of normal granulocytes and histiocytes but not in neoplastic histiocytes.

Aged↗

Differences between muscular receptors and neural receptors for cholecystokinin-octapeptide in the guinea-pig gallbladder.

To investigate the differences between muscular and neural receptors for cholecystokinin-octapeptide (CCK-OP) in the guinea-pig gallbladder, we studied the effects of dibutyryl cyclic GMP (dbc GMP) on CCK-OP-evoked contraction and [3H]acetylcholine (ACh) release. 10(-3) M dbc GMP significantly reduced CCK-OP (10(-8) M)-evoked contractions without affecting the peptide-induced [3H]ACh release. It is suggested that there are two types of CCK-OP receptors in the guinea-pig gallbladder (dbc GMP-sensitive muscular receptors and dbc GMP-insensitive neural receptors).

Acetylcholine↗

Adenosine 5'-triphosphate release evoked by electrical nerve stimulation from the guinea-pig gallbladder.

The endogenous release of adenosine 5'-triphosphate (ATP) from strips of guinea-pig gallbladder during transmural stimulation (TS) was measured with a firefly luciferine-luciferase reaction. TS (15V, 1 ms, 0.5-5 Hz, for 1 min) caused a rapid and marked increase of ATP release in a frequency-dependent manner. Both ATP release and contractions evoked by TS (15 V, 5 Hz, 1 ms) were completely abolished in Ca-free medium. BaCl2 (3 X 10(-3) M), a direct muscle stimulant, produced almost the same degree of contractile tension as TS (15 V, 5 Hz, 1 ms) while the ATP release induced by BaCl2 was significantly reduced to about 60 percent of that induced by TS. Atropine (10(-6) M) significantly reduced TS-evoked contraction without affecting ATP release. It was suggested, therefore, that some of the ATP release induced by TS was of neural origin. Theophylline (a P1-purinoreceptor antagonist) 10(-6) M, quinidine (a non-specific P2-purinoreceptor antagonist) 10(-6) M and apamin (a potassium channel blocking agent) 10(-8) M had no effects on TS-evoked contraction and ATP release, suggesting the absence of a presynaptic autoregulatory mechanism of ATP release in the guinea-pig gallbladder.

Adenosine Triphosphate↗

Experimental allergic encephalomyelitis mediated by murine encephalitogenic T cell lines specific for myelin proteolipid apoprotein.

T cell lines specific for bovine myelin proteolipid apoprotein (PLP) were established from SJL/J mice. The line cells bore surface phenotypes of T helper/inducer cells (Lyt-1+, Lyt-2-, L3T4+) and responded well to bovine, rat, and guinea pig PLP but not to myelin basic protein. One line responded to major PLP, and another responded to both major PLP and DM-20, which are the two major intrinsic membrane proteins of the central nervous system (CNS) myelin. Intraperitoneal inoculation of 4 to 30 X 10(6) PLP-activated line cells followed by injection of pertussis vaccine induced acute inflammatory disease of the CNS, with typical clinical signs of EAE mostly in a week in recipient mice that had been treated with low-dose irradiation. Almost all animals recovered completely, and two of the 12 animals relapsed 42 or 75 days after inoculation. The lesions were restricted to the CNS and were characterized by perivascular and parenchymal infiltration of inflammatory cells, fibrin deposit, and demyelination. In the severe lesions, axons were also damaged. These observations suggest that PLP is a definite encephalitogen, and PLP-sensitized effector T cells induce inflammatory demyelination in the CNS.

Animals↗

Choledochal cyst. Its possible autonomic involvement in the bile duct.

The properties of the choledochal cyst were compared with those of the normal common bile duct. Cholecystokinin-octapeptide and a high concentration of acetylcholine produced smaller contractions in the strips of the narrow portion of the cyst than in the strips of the dilated portion and the normal common bile duct. Nicotine did not cause contractions in the strip of the narrow portion of the cyst. gamma-Aminobutyric acid (GABA) induced atropine-sensitive, tetrodotoxin-sensitive contractions in the bile ducts through bicuculline-sensitive, furosemide-sensitive GABAA receptors located on the postganglionic cholinergic neuron. The GABA did not induce contractions in the narrow portion of the cyst. The number of ganglion cells was decreased markedly in the same portion. These findings suggest that the choledochal cyst has postganglionic neural dysfunction. This character may be one of the causes of cyst formation.

Acetylcholine↗

SEM-EPMA observation of three types of apatite-containing glass-ceramics implanted in bone: the variance of a Ca-P-rich layer.

The progressive changes of a Ca-P-rich layer between bone and three types of apatite-containing glass-ceramics of the same chemical composition: MgO 4.6, CaO 44.9, SiO2 34.2, P2O5 16.3, CaF2 0.5 (in weight ratio) were examined. Plates (15 mm X 10 mm X 2 mm, mirror surface) containing apatite (35 wt%) (designated A-GC), apatite (35 wt%) and wollastonite (40 wt%) (designated A.W-GC), and apatite (20 wt%), wollastonite (55 wt%), and whitlockite (15 wt%) (designated A.W.CP-GC) were prepared. They were implanted into the tibia of mature male rabbits for 5 days, 10 days, 20 days, 30 days, 60 days, 6 months, and 12 months. All three types of glass-ceramics showed direct bonding to the bone 30 days after implantation. It was observed by SEM-EPMA 30 days after implantation that Si and Mg content decreased, P content increased, and Ca content did not change across the reactive zone from the glass-ceramics to bone. The level of P and Si in the A.W.CP-GC changed five days after implantation. In A.W-GC and A-GC, a little change in P and Si levels was observed between 10 and 20 days after implantation. The width of reactive zone was narrowest with A-GC, wider with A.W-GC, and widest with A.W.CP-GC. The dissolution of glass-ceramics stopped 6 months after implantation. This phenomenon shows that the glass-ceramics may be suitable for clinical use.

Animals↗

Progesterone inhibits the contractile motility of the guinea pig gallbladder.

We studied the effects of progesterone on the contractile motility of the guinea pig gallbladder in vitro. Carbachol (10(-6) M) induced contractions were reduced by the pretreatment with progesterone (10(-8)-10(-6) M) in a dose-dependent manner. Concentration-response curves for carbachol, histamine and CCK-OP showed inhibition by progesterone (5 X 10(-7) M). These results suggest that progesterone has a direct inhibitory effect on gallbladder smooth muscle. Contractile responses to potassium (10-60 mM) or calcium (0.4-3.2 mM), which were thought to activate the contractile machinery by increasing the influx of extracellular calcium, were not affected by the pretreatment of progesterone. The direct inhibitory effects of progesterone on gallbladder smooth muscle might be explained by the inhibition of calcium release from the intracellular storage sites.

Animals↗

Dual action of cholecystokinin-octapeptide on the guinea pig antrum.

We examined the mechanism of action of cholecystokinin-octapeptide (CCK-OP) on longitudinal strips of the lesser and greater curvatures of the guinea pig antrum. In the strips of the lesser curvature, CCK-OP produced a concentration-dependent tonic contraction, which was significantly reduced by atropine, but not by tetrodotoxin. In contrast, CCK-OP caused a relaxation of the preparation of the greater curvature in a concentration-dependent manner. The relaxation induced by the peptide was enhanced by atropine, whereas it was blocked by tetrodotoxin. Propranolol, phentolamine, desensitization to adenosine-5'-triphosphate, and desensitization to vasoactive intestinal polypeptide had no effect on CCK-OP-induced relaxation. Cholecystokinin-octapeptide evoked the release of acetylcholine from strips of both sides, and it was not blocked by tetrodotoxin. These findings indicate that the mechanism of action of CCK-OP on the lesser curvature differs from that on the greater curvature. The peptide seems to act directly on smooth muscle cells and to stimulate cholinergic neural activity by sodium channel-independent mechanisms. Additionally, nonadrenergic inhibitory neurons appear to be activated by CCK-OP in the greater curvature.

Animals↗

Suppression of experimental allergic encephalomyelitis by 15-deoxyspergualin.

15-Deoxyspergualin (DSG), a novel antitumor antibiotic, was tested for treatment of acute experimental allergic encephalomyelitis (EAE) in Lewis rats. Clinical and histologic signs of EAE by active sensitization with myelin basic protein were profoundly inhibited by prophylactic administration of DSG in a dose-dependent manner. By the treatment during the inductive phase, the onset of EAE was significantly delayed. Antigen-specific proliferation of lymph node cells and the ability of spleen cells to transfer EAE were suppressed but concanavalin A-induced lymphocyte proliferation was not altered. Passive EAE induced with an encephalitogenic T cell line was also prevented by DSG-treatment, although DSG did not suppress but rather augmented the activation of T cells in vitro. Taken together, DSG is not a non-specific lymphocyte toxin but a unique immunomodulator that can suppress both inductive and effector phases of EAE.

Animals↗