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Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

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

Determination of 17-oxosteroids in serum and urine by fluorescence high-performance liquid chromatography using dansyl hydrazine as a pre-labeling reagent.

A fluorescence high-performance liquid chromatographic method is described for the determination of 17-oxosteroids in biological fluids. 17-Oxosteroids in urine samples are extracted with dichloromethane after enzymatic hydrolysis (beta-glucuronidase-sulfatase), and dehydroepiandrosterone sulfate in serum samples is solvolysed with sulfuric acid in ethyl acetate. 17-Oxosteroids are labeled with dansyl hydrazine in trichloroacetic acid-benzene solution, and then chromatographed on the microparticulate silica gel column using dichloromethane-ethanol-water (400 : 1 : 2) as the mobile phase. The eluate is monitored by a fluorophotometer at 365 nm (excitation) and 505 nm (emission). Linearities of the fluorescence intensities (peak heights) with the amounts of various 17-oxosteroids were obtained between 60 and 1000 pg. The assay proved satisfactory with respect to sensitivity, precision and accuracy. The results obtained by a radioimmunoassay and this method were in good agreement (r = 0.964, n = 81) for serum dehydroepiandrosterone sulfate. This method is also use for the simultaneous determination of individual 17-oxosteroids in serum and urine.

17-Ketosteroids↗
PubMed1981

The branching and linear portions of poly(adenosine diphosphate ribose) have the same alpha(1 leads to 2) ribose-ribose linkage.

The structure of the branching site of poly(ADP-ribose) was determined as O-alpha-D-ribofuranosyl-(1"' leads to 2")-O-alpha-D-ribofuranosyl-(1" leads to 2')-adenosine-5',5",5"'-tris(phosphate) by gas chromatography, mass spectrometry, and 1H-NMR measurements. Thus the structures of all the ribose-ribose linkages known in poly(ADP-ribose) are uniformly alpha(1 leads to 2)glycosidic bond. This indicates that branching ADP-ribosylation and elongating ADP-ribosylation of poly(ADP-ribose) synthesis are catalyzed by similar alpha(1 leads to 2)-specific ADP-ribosyl transferases or the same enzyme. Poly(ADP-ribose) glycohydrolase, which specifically hydrolyzes the ribose-ribose bonds of poly(ADP-ribose), also cleaves the ribose-ribose-ribose bonds at the site of branching.

Chromatography, Gas↗
PubMed1981

Presence of the phospholipid methylation pathway in mammalian cultured cells.

Stepwise N-methylation of phosphatidylethanolamine to phosphatidylcholine was examined by measuring incorporation of the radioactive methyl group of S-adenosylmethionine into phosphatidyl-N-monomethylethanolamine, phosphatidyl-N,N'-dimethylethanolamine and phosphatidylcholine by membranes of five mammalian cultured cell lines (BHK-21 cells, Chang liver cells, PC-12 h cells, MOPC-31C cells and LM cells). The three successive methylation steps were found in all the cells studied, though the total incorporation and the distribution profile of the radioactivity among the products differed with different cells. Furthermore, increase in the amounts of phosphatidyl-N-monomethylethanolamine and phosphatidyl-N,N'-dimethylethanolamine in the amine and N,N'-dimethylethanolamine, respectively, resulted in increased methylation of phospholipids. This remarkable enhancement of methylation seems to be a characteristic effect of such modification of membrane phospholipids in mammalian cultured cells.

Animals↗
PubMed1981

Pancreatic exocrine secretion and immunoreactive secretin release after intraduodenal instillation of 1-phenyl-1-hydroxy-n-pentane and HCl in rats.

Portal plasma immunoreactive secretin (IRS) concentrations, pancreatic juice flow, and amylase output were simultaneously measured in response to intraduodenal infusion of 1-phenyl-1-hydroxy-n-pentane (PHP), as well as infusion of hydrochloric acid (HCl). These data were compared with those obtained from intravenous bolus injections of synthetic porcine secretin in anesthetized rats. The intraduodenal infusion of PHP or HCl at a rate of 2 ml/min for 2 min produced a dose-related increase in portal plasma secretin concentrations, pancreatic juice flow, and amylase output. However, the mechanism of secretin release by PHP seems to differ from that of HCl. The secretin response to 0.1 N HCl infused at a rate of 0.1 ml/min for 30 min was complete after 10 min, despite continued infusion, while PHP stimulated a secretin release which persisted for 10 min after cessation of infusion. The pH in the second portion of the duodenum, following PHP infusion, remained consistently greater than 6.3. PHP-stimulated pancreatic exocrine secretions were only partially suppressed by somatostatin, while secretin release was almost completely inhibited. However, intraduodenal PHP may stimulate the release of secretin along with other gastrointestinal hormones, and the endogenous release of these hormones may not be inhibited by somatostatin.

Amylases↗
PubMed1981

Clinical evaluation of amylase-creatinine clearance ratio and amylase isoenzyme clearance in chronic renal failure.

Amylase-creatinine clearance ratio (ACCR) and amylase isoenzyme clearance were determined simultaneously in patients with chronic renal failure. ACCR in patients with compensated renal failure (3.5 +/- 0.4%) was not significantly different from normals (2.6 +/- 0.2%), while that in patients with non-compensated renal failure (6.7 +/- 0.4%) was significantly higher than that in normals. Clearance ratio of pancreatic isoamylase (Amylase-1) relative to creatinine clearance (CAmy . 1/Ccr) in patients with both compensated (5.9 +/- 1.0%) and non-compensated (6.8 +/- 0.4%) renal failure was as high as that in patients with acute pancreatitis (6.6 +/- 0.5%). On the other hand, clearance ratio of salivary isoamylase (Amylase-3) relative to creatinine clearance (CAmy . 3/CCr) in patients with compensated renal failure (1.5 +/- 0.3%) was almost the same as that in normals (2.1 +/- 0.1%), while that in patients with non-compensated renal failure was 5.9 +/- 0.7%, which was significantly higher than that in normals. The present study revealed that elevated ACCR in patients with severely impaired renal function was due to the increase of the clearance ratio for both pancreatic and salivary amylase. These facts suggested that glomerular permeability and tubular reabsorption for pancreatic and salivary amylase might play an important role on ACCR in patients with severely impaired renal function.

Amylases↗
PubMed1981

Chemiluminescence enzyme immunoassay of dehydroepiandrosterone and its sulfate using peroxidase as label.

We report a highly sensitive enzyme immunoassay for dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S) using horseradish peroxidase as the label enzyme. Separation of free and bound DHEA-peroxidase conjugate was by insolubilized antibody, prepared by coupling purified IgG of goat anti-rabbit IgG serum with Sepharose 4B or a polystyrene tube. The enzyme activity was measured by the chemiluminescence reaction using luminol and hydrogen peroxide as substrate. The faint chemiluminescence was measured by a photon counter. The sensitivity was 25 pg/assay tube for DHEA and 100 pg/assay tube for DHEA-S. Upon comparison, results obtained by radioimmunoassay and this method showed good agreement ; r = 0.86 for free DHEA, r = 0.92 for acid-hydrolyzed DHEA-S and r = 0.91 for solvolyzed DHEA-S. The present method is applicable in the routine determination of DHEA and DHEA-S in biological fluid.

Dehydroepiandrosterone↗
PubMed1981

Synthesis of seleno- and thioguanine-platinum(II) complexes and their antitumor activity in mice.

Selenoguanine-, selenoguanosine-, thioguanine-, and thioxanthine-platinum(II) complexes were synthesized, and their antitumor activities were studied against L1210 cells in mice and in an in vitro system. These compounds exhibited antitumor activity of medium strength and showed very low toxicity. The effect of the selenoguanine-platinum(II) complex in mice was retained longer than that of the parent compound, selenoguanine, because the selenoguanine-platinum(II) complex very slowly released selenoguanine into the blood.

Animals↗
PubMed1981

Radioimmunoassay of cyclazocine and stereospecificity of antibody.

A new radioimmunoassay, using 3H-cyclazocine, rabbit antiserum and charcoal-dextran separation of bound and free cyclazocine, for the direct analysis of serum cyclazocine is described. This method, which is specific for cyclazocine and has a detection limit of ca. 25 pd/assay tube, was successful in determining the cyclazocine level in the sera of beagles intramuscularly injected with 3 or 10 microgram/kg cyclazocine. The drug half-life was 90 min; the apparent distribution volumes were 4.0 and 5.26 liter/kg, respectively. One of the antisera raised in rabbits immunized with dl-cyclazocine derivative-BSA conjugates was highly specific for l-cyclazocine.

Animals↗
PubMed1981

Pathological changes in laying hens inoculated with the JPA-1 strain of egg drop syndrome-1976 virus.

Rhode Island Red laying hens were inoculated with the JPA-1 strain of egg drop syndrome-1976 virus and examined pathologically 1, 3, 5, 7, 10, 14, 21, 28 and 80 days postinoculation (p.i.). Eggs with a discolored or soft shell or no shell were laid over a period from 10 to 24 days p.i. Egg production failed transiently in some affected birds after 13 days p.i. At autopsy, the uterus revealed remarkable edema and swelling of the mucosal folds together with the deposition of whitish exudate in the cavity 14 days p.i. Microscopically, intranuclear inclusion bodies were found in epithelial cells of the uterus, isthmus and vaginal gland region 10 and 14 days p.i. There were also severe degeneration and desquamation of the epithelial cells, atrophy of the uterine glands and remarkable infiltration of heterophils, lymphocytes and plasmacytes accompanied with extensive edema. Twenty-one days after inoculation, lymphoid follicles were formed in the mucosal folds of some part of the oviduct. Electron microscopic examination revealed various amounts of virus particles 68 approximately 80 nm in diameter mainly in the nuclei of the epithelial cells on the mucosa and in the exudate, and also in the cytoplasm of macrophages in the uterus.

Adenoviridae Infections↗