PubMed Health⌕ Search

Biomedical subjects

H Azuma

Publications and source records attributed to H Azuma.

At least 289 records · Page 16Linked to original sources
PubMed1980

Stimulatory action of lisuride on dopamine-sensitive adenylate cyclase in the rat striatal homogenate.

Effect of lisuride, an ergot derivative of isolysergic structure, on dopamine-sensitive adenylate cyclase was studied in the homogenate of rat corpus striatum. Stimulatory action of lisuride, similar to the actions of dopamine and apomorphine, on striatal adenylate cyclase was potentiated significantly by guanosine triphosphate (GTP) and by guanyl-5'-yl imidodiphosphate (GMP-PNP), although with lisuride alone, there was only a slight stimulation. The maximal stimulation attained in the presence of GTP corresponded to about 1.4 times the basal rate of cyclic AMP formation in the homogenate and was abolished by an addition of haloperidol. Lisuride at a concentration about 3 microM inhibited stimulation of cyclic AMP formation by dopamine. The effect of lisuride and the extent of potentiation by the guanyl nucleotides were almost comparable to the effects of apomorphine, under corresponding conditions. Thus, lisuride, like apomorphine, acts as a partial agonist-antagonist, and has the ability to stimulate the dopamine-sensitive adenylate cyclase in the rat corpus striatum.

Adenylyl Cyclases↗
PubMed1980

[Biliary transport of organic anions in the isolated hemoglobin-free perfused rat liver (author's transl)].

Mechanisms involved in the biliary excretion of organic anions were investigated in hemoglobin-free perfused rat liver using iotroxic acid as a test substance. The process of biliary excretion in this system can be separated into three elemental processes, i.e. 1) diffusion into hepatocytes, 2) protein-binding with intracellular protein (accumulation) and 3) active transport into bile. Elimination of iotroxic acid from the perfusate into the hepatocytes followed first-order kinetics, indicating the process to be that of passive diffusion. Though the biliary excretion occurred rather rapidly, the amount of iotroxic acid in the hepatocytes increased with increases in the initial concentration in the perfusate and approached a maximal amount of ca. 2.8 mu moles/g wet weight of liver. The maximal values observed for the biliary concentration and the rate of biliary transport were 20-24 mM and 38-48 nmoles/min . g liver, respectively. Bromsulphalein inhibited the diffusion of iotroxic acid into the hepatocytes whereas accumulation of iopodic acid in the hepatocytes produced an inhibition of diffusion into the hepatocytes and transport into the bile. Dexamethasone-21-sulfate (DXMS) was transported rapidly into the bile, but in the presence of iotroxic or iopodic acids, excretion of DXMS into the bile was inhibited, while diffusion into the hepatocytes was inhibited only by iopodic acid. The competition observed with those substances demonstrates the presence of a common mechanism for the biliary transport of organic anions in the liver.

Animals↗
PubMed1980

[Chemical structure biliary excretion of iodine-containing contrast agents in hemoglobin-free perfused rat liver and in vivo (author's transl)].

Pharmacokinetical properties of eight triiodobenzene derivatives, X-ray contrast agents, were studied in the hemoglobin-free perfused rat liver with emphasis on the structural relation to biliary transport. With chemical modification of the basic structure, these agents showed different characteristics in the processes of diffusion into hepatocytes, accumulation in the cells and active transport into the bile, and were separated into four groups; [I]: Iotroxic acid (1), Iodipamic acid (2), Iodoxamic acid (3), and Ioglycamic acid (4) which showed faster rates of diffusion into hepatocytes [(1) greater than or equal to (2) greater than (3) greater (4)] and also of biliary excretion [(1) greater than (2) greater than (4) greater than (3)], [II]: Diatrizoic acid and Metrizamide showed poor diffusion and biliary excretion, [III]: Iopodic acid showed the highest permeability into and accumulation in hepatocytes with little biliary excretion, [IV]: ZK73 215 was slowly transported into the bile, yet, showed little permeation through the cell membrane. Characteristics of (1), (2) and (3) observed in the perfused liver were, in principle, confirmed in the pharmacokinetical profile observed in vivo. However, the fast diffusion of (2) into the hepatocytes appears to be hampered by high binding ability with serum proteins, whereas the relatively poor profile of the biliary excretion of (3) was improved by its low protein-binding in blood in vivo. Superiority of (1) as a cholangiographic agent was demonstrated by the fast biliary excretion in both the case of experimental systems and moderate protein-binding.

Animals↗
PubMed1980

[A histopathological study on aging process of the acetabulum with special reference to the pathogenesis of the acetabular cyst (author's transl)].

This is to report the aging process of the acetabula studied as an aid to the investigation of the pathogenesis and progression of osteoarthritis of the acetabulum. The material consisted of 45 acetabula obtained from 45 fresh cadavers. Regarding the morphological changes of the labrum-cartilage junction of middle and old age groups, marked degenerative changes such as tear, detachment, fissuring and scar formation were observed in many cases at the loaded part of the acetabulum. Among these, a loose connective tissue had invaded into the subchondral space through a fissure in one case, and infusion of the joint fluid into a fissure was observed in another. All of the 3 acetabular cysts were from the middle and old age groups and at the weight-bearing portions of the acetabula. All cysts were found to have communication with the joint cavities through the fissures. The trabeculae surrounding the cysts showed slight destructive changes apparently due to compression by the cysts. The above findings would suggest that the cyst formation as an aging process at the weight-bearing portions is probably due to infusion of the joint fluid into the subchondral space through the fissure at the labrum-cartilage junction or through the fissure at the junction resulting from subchondral plate fracture, although some additional causative factors might also play a role in the process.

Acetabulum↗
PubMed1980

[Aging process of the acetabulum with special reference to the osteophyte formation (author's transl)].

Osteophyte formation at the acetabulum was investigated in connection with aging and osteoarthritis. The materials consisted of 39 specimens of the acetabula obtained from fresh cadavers ranging from 14 to 89 years of age. Of those two of the specimens were in the second decade, two in the third, and others were over 40. Osteophyte appeared at three parts of the acetabula; the peripheral part, the foveal area and the lower portion at the ligamentous attachment. Two types of the peripheral osteophytes were distinguished from their growth direction, and in some sections both types were observed together. Foveal osteophytes were recognized at the rim of the semilunar cartilage in the advanced age group and a double acetabular floor was formed by both the osteophytic projection and the existing foveal trabeculae. In some cases there were small osteophytes formed in the ligamentous tissue at the lower ends of the acetabula. As distribution and growth of the osteophytes in the aging process were in accord with those in osteoarthritis, it would be reasonable to assume that the osteophyte formation in aging might be one of the initial changes of the development of osteoarthritis.

Acetabulum↗
PubMed1978

[Pharmacological properties of N-(3',4'-dimethoxycinnamoyl) anthranilic acid (N-5'), a new anti-atopic agent. (3).--Influence on homologous passive cutaneous anaphylaxis mediated by homocytotropic antibody (author's transl)].

N-5' shows a potent inhibitory action on the homologous passive cutaneous anaphylaxis (PCA) in rats mainly through the inhibition of histamine release from mast cells. The present experiment was an attempt to clarify in detail the pharmacological properties of N-5'. Inhibition of PCA was most potent at 30 or 60 min pretreatment with N-5', and negligible at 240 min pretreatment. Given p.o., N-5' produced a dose-dependent, potent inhibitory action at 30-min pretreatment. On the other hand, disodium cromoglycate (DSCG) had little effect on PCA when given orally. On the case of i.v. administration, N-5' (20 mg/kg) and DSCG (5 mg/kg) showed a most potent inhibition of PCA at 5 min pretreatment. The inhibitory action of DSCG was, however, shorter lasting than that of N-5'. Median effective doses (ED50) of DSCG and N-5' on the PCA were estimated to be 0.79 and 8.8 mg/kg i.v., respectively. Inhibitory activity of N-5' in the adrenalectomized rat did not differ from that in sham operated animals. N-5' had a more potent inhibitory action on the PCA in infant rats than in adults. Inhibitory activity of N-5' in the case of 1, 2, 3 and 4 weeks of successive administration was equipotent to that with a single administration.

Administration, Oral↗
PubMed1976

Pharmacological properties of N-(3',4'-dimethoxycinnamoyl) anthranilic acid (N-5'), a new anti-atopic agent.

1 N-(3'-4'-dimethoxycinnamoyl) anthranilic acid (N-5') exhibited a dose-dependent, potent inhibition of the passive cutaneous anaphylaxis (PCA) mediated by homocytotropic antibodies (HTA), which was hardly affected by anti-inflammatory agents such as phenylbutazone, indomethacin and prednisolone at any dose used. The HTA-induced PCA was significantly inhibited by combined treatment with diphenydramine and cyproheptadine. 2 Doses of N-5' which potently inhibited HTA-induced PCA inhibited only slightly the heterologous PCA produced by anti-bovine serum albumin (BSA) rabbit serum. This heterologous PCA was clearly inhibited by phenylbutazone, indomethacin and prednisolone. Diphenydramine and cyproheptadine, singly or combined inhibited the heterologous PCA only slightly. 3 The increased vascular permeability caused by histamine and 5-hydroxytryptamine was significantly inhibited by diphenyldramine or cyproheptadine, but not by N-5' and the anti-inflammatory agents used. 4 N-5' 150 mg/kg orally inhibited rat paw oedema induced by carrageenin by about 26% while phenylbutazone, indomethacin and prednisolone produced significant inhibition. 5 N-5' at concentrations of 100 and 1000 muM significantly inhibited (by about 52% and 95%, respectively) the histamine release from rat peritoneal cells induced by HTA; 10 muM N-5' had little effect. Histamine release was inhibited by phenylbutazone or indomethacin at 1000 muM but not at 100 muM. Prednisolone had no effect on histamine release at any of the concentrations used. 6 These findings suggest that the inhibition of the HTA-induced PCA by N-5' may be due to inhibition of histamine release and is clearly different from the actions of anti-inflammatory agents such as phenylbutazone, indomethacin and prednisolone.

Animals↗
PubMed1976

Treatment of chronic osteomyelitis by transplantation of autogenous omentum with microvascular anastomosis. A preliminary report.

Free omental transplantation with vascular anastomosis was attempted in three clinical cases as a new method of treatment for chronic osteomyelitis. The bone cavity produced by debridement was completely eliminated by the transplanted omentum. Furthermore, the omentum, because of its biological characteristics, formed good vascular anastomoses with the adjacent bone tissue. Although sufficient time has not yet elapsed to prove the existence of healthy bone regeneration and therefore, further evaluation for a longer period is necessary, this therapeutic method would seem to have considerable potential in the treatment of chronic osteomyelitis.

Adult↗
PubMed1976

[Pharmacological actions of a new antihypertensive drug, olmidine, on the gastrointestinal tract].

It has been reported that dl-2-(3,4-methylenedioxyphenyl)-2-hydroxyacetamide hydrochloride (Olmidine) shows an antihypertensive action through inhibition of the adrenergic transmission. The present experiment was an attempt to investigate the pharmacological actions of olmidine in the alimentary canal of rat, rabbit and guinea pig. We found that the salivary secretion of rabbit was unaffected by olmidine at a dose of 2 mg/kg i.v., but increased by approximately 3 times that of controls with 10 mg/kg i.v.. Volume of gastric juice, concentration of free HCl, total acidity and pH of gastric juice in Shay rats were unaffected by 20 mg/kg i.p. of olmidine while volume and free HCl were significantly reduced at a dose of 100 mg/kg i.p. of the drug. The pH of gastric juice showed an evident increase to 3.33. Total acidity, however, was unaffected. Bile secretion of rat was decreased by olmidine at a dose of 100 or 500 mg/kg i.p. in a dose-dependent manner. Olmidine did not induce any lesion of gastric mucosa of rats at a dose of 200 mg/kg p.o. or less. Movement of charcoal meal in the small intestine of rats was inhibited by olmidine at doses of 20 to 500 mg/kg p.o.. Olmidine caused a biphasic response, that is contraction followed by a relaxation,in the isolated guinea pig gastrointestinal tracts. The contractile response caused by olmidine was completely inhibited by pretreatment with atropine or scopolamine and converted to one of relaxation which was unaffected by a combined treatment with phentolamine and propranolol. Contractile responses caused by transmural stimulation were significantly potentiated by olmidine, while potentiation of the contractile responses caused by exogenously applied acetylcholine was only slight in the isolated gallbladder from guinea pig.

Amidines↗
PubMed1976

Regulation of bacterial motility by cyclic nucleotides and effect of biogenic amines.

When assayed by a newly devised, simple and quantitative method, "motilometry", the motility of E. coli S-26 was found stimulated by cyclic adenosine 3':5'-monophosphate (cyclic AMP) and 8-hydroxy cyclic AMP as well as histamine, catecholamines and inhibited by cyclic guanosine 3':5'-monophosphate (cyclic GMP). The stimulation elicited by cyclic AMP or other biogenic amines was reversed by cyclic GMP. The experimental significance and implicaton of these findings are discussed.

Adenosine↗
PubMed1975

Desferrioxamine B, an inhibitor of Escherichia coli motility, reversing the stimulating effect of cyclic adenosine 3',5'-monophosphate.

A substance inhibiting Escherichia coli motility was isolated by "motilometry" assay from the culture broth of Streptomyces sp. strain NR9GG8 and was found to be identical with desferrioxamine B. Its inhibitory effect was reversed by cyclic adenosine 3',5'-monophosphate (cAMP), while the motility stimulation by cAMP was diminished by this inhibitor. Its effects on various enzymes involved in cAMP metabolism of function of cAMP were examined.

Cyclic AMP↗