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Biomedical subjects

B A Bailey

Publications and source records attributed to B A Bailey.

36 records · Page 2Linked to original sources
PubMed1992

Alterations in Nicotiana tabacum L. cv Xanthi Cell Membrane Function following Treatment with an Ethylene Biosynthesis-Inducing Endoxylanase.

An ethylene biosynthesis-inducing xylanase (EIX) produced by the fungus Trichoderma viride elicited enhanced ethylene biosynthesis and leakage of potassium and other cellular components when applied to leaf disks of tobacco (Nicotiana tabacum L. cv Xanthi). Suspension-cultured cells of Xanthi tobacco responded to EIX by rapid efflux of potassium, uptake of calcium, alkalization of the medium, inhibition of ethylene biosynthesis, and increased leakage of cellular components. EIX-treated cell suspensions released 1-aminocyclopropane-1-carboxylate (ACC) into the surrounding medium, resulting in a reduction of cellular pools of ACC. The responses of both cell suspensions and leaf disks were inhibited (50-80%) by the preincubation of the tissues with the calcium channel blocker La(3+). High concentrations of EGTA inhibited the alkalization of the medium by cell suspensions responding to EIX, but EGTA alone caused extensive loss of K(+) and ACC and inhibited ethylene biosynthesis by tobacco cells. Alterations in membrane function appear to be important in the mode of action of EIX in Xanthi cells.

Journal Article↗
PubMed1992

Characteristics of ethylene biosynthesis-inducing xylanase movement in tobacco leaves.

(125)I-Labeled ethylene biosynthesis-inducing xylanase (EIX) was used to study the movement of this protein in tobacco (Nicotiana tabacum) tissues. A biologically active (125)I-labeled EIX was obtained using chloramine-T as the oxidizing agent. Labeled EIX was detected in the far most edges of the leaf 5 min after it was applied to the petiole of a detached leaf. EIX was distributed uniformly throughout the leaf, including the mesophyll area within 5 to 15 min, after which there was only little change in the distribution of radioactivity in the leaf. (125)I-Labeled EIX was extracted from treated leaves, and EIX translocation in the leaf was blocked by preincubation of labeled EIX with anti-EIX antibodies, indicating that the intact peptide moves in the leaf. Injection of anti-EIX antibodies into the intercellular spaces of the leaf mesophyll prevented induction of necrosis by EIX, suggesting the mesophyll as the site of EIX action. EIX was translocated both to upper and lower parts of the plant when applied to a whole plant through the petiole of a cut leaf. Radioactivity was found in all leaves and in the stem, although some leaves accumulated much more EIX than others; EIX was not found in the roots. There was no difference between the accumulation pattern of EIX in fresh and ethylene-treated leaves or between sensitive (Xanthi) and insensitive (Hicks) tobacco cultivars. These data support the hypothesis that intact EIX protein is translocated to the leaf mesophyll, where it directly elicits plant defense responses.

Journal Article↗
PubMed1991

Maize microsomal benzoxazinone N-monooxygenase.

The benzoxazinones occur in hydroxamic acid and lactam forms in maize (Zea mays L.) tissue. The hydroxamic acid forms which possess a N-hydroxyl group are found in the highest concentration while the lactam members which lack the N-hydroxyl group occur in lower concentrations. The hydroxamic acid 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) has as its lactam counterpart 2-hydroxy-1,4-benzoxazin-3-one (HBOA). An enzyme has been identified in maize microsomal preparations which catalyzes the N-hydroxylation of HBOA to form DIBOA. The enzyme is initially observed in seedlings 2 days after imbibition which coincides with the onset of hydroxamic acid accumulation. The enzyme requires NADPH and is inhibited by sulfhydryl reagents, NADP, cytochrome c, cations, carbon monoxide, and nitrogen gas. The effect of nitrogen can be reversed by exposing the enzyme to air, while the effect of carbon monoxide can be reversed by exposing the enzyme to 450 nanometer light during the incubation period. The apparent K(m) values for HBOA and NADPH are 13 and 5 micromolar, respectively. The pH optimum is 7.5 and the temperature optimum for the enzyme is 35 degrees C. A 450 nanometer absorbance peak is observed when reduced microsomal preparations are exposed to carbon monoxide which in combination with other data presented supports the hypothesis that the enzyme is a cytochrome P-450 dependent N-monooxygenase.

Journal Article↗
PubMed1991

Ethylene Biosynthesis-Inducing Endoxylanase Is Translocated through the Xylem of Nicotiana tabacum cv Xanthi Plants.

Ethylene biosynthesis-inducing xylanase (EIX) from the fungus Trichoderma viride elicits enhanced ethylene production and tissue necrosis in whole tobacco (Nicotiana tabacum cv Xanthi) plants at sites far removed from the point of EIX application when applied through a cut petiole. Symptoms develop in a specific pattern, which appears to be determined by the interconnections of the tobacco xylem. Based on results of tissue printing experiments, EIX enters the xylem of the stem from the point of application and rapidly moves up and down the stem, resulting in localized foliar symptoms on the treated side of the plant above and below the point of EIX application. The observation that a fungal protein that elicits plant defense responses can be translocated through the xylem suggests that plants respond to pathogen-derived extracellular proteins in tissues distant from the invading pathogen.

Journal Article↗
PubMed1990

An Ethylene Biosynthesis-Inducing Endoxylanase Elicits Electrolyte Leakage and Necrosis in Nicotiana tabacum cv Xanthi Leaves.

We have previously demonstrated that a protein purified from xylan-induced culture filtrates of Trichoderma viride contains beta-1,4-endoxylanase activity and induces ethylene biosynthesis in tobacco (Nicotiana tabacum cv Xanthi) leaf discs. When the ethylene biosynthesis-inducing xylanase (EIX) was applied to cut petioles of detached tobacco leaves, it induced ethylene biosynthesis within 1 hour and extensive electrolyte leakage and necrosis were observed in tobacco leaf tissue within 5 hours. Ethylene-pretreatment (120 microliters per liter ethylene for 14 hours) of tobacco leaves enhanced ethylene biosynthesis in response to EIX by more than threefold and accelerated development of cellular leakage and necrosis. In intact plants, similar symptoms could be induced in leaves that were distant from the point of the enzyme application. The evidence suggests that EIX is translocated via the vascular system and elicits plant responses similar to those observed in a hypersensitive response.

Journal Article↗
PubMed1990

Effect of experience with nontraditional workers on psychological and social dimensions of occupational sex-role stereotyping by elementary school children.

AngloAmerican and Hispanic boys and girls ages 6 to 11 yr. (N = 219) were exposed to nontraditional workers within their elementary school classrooms. They rated 30 occupations as appropriate for men, women, or both men and women, on a pre- and posttest for a social dimension score (attribution of occupational sex-role stereotypes to others). Pre- and posttest fixed-choice selection of individual career aspirations indicated a psychological dimension score (individual job preference). Traditionality was measured from the child's point of view, not an adult concensus. Analysis shows: (a) When students are exposed to nontraditional role models their attitudes become less sex-typed on the social but not on the psychological dimension. (b) Sex and age affected career choices. (c) Historical-cultural (i.e., women's movement) events appear to have affected the children's attitudes on the social dimension.

Career Choice↗
PubMed1989

Hydroxamic Acid glucosyltransferases from maize seedlings.

Hydroxamic acids occur in several forms in maize (Zea mays L.) with 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) being the predominant form and others including 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) being found at lower concentrations. Two enzymes capable of glucosylating hydroxamic acids were identified in maize protein extracts and partially purified and characterized. The total enzyme activity per seedling increased during the first 4 days of germination and was concurrent with the accumulation of DIMBOA. Purification of the enzymes by ammonium sulfate precipitation followed by Sephadex G-200 and Q-Sepharose gel chromatography resulted in a 13-fold increase in specific activity. The enzymes are initially separated into two peaks (peak 1 and peak 2) of activity by Q-Sepharose gel chromatography. The peak 1 glucosyltransferase had 3.6% of the DIMBOA glucosylating activity when DIBOA was used as substrate, whereas this percentage increased to 57% for the peak 2 enzyme. The enzyme in peak 2 has a K(m) of 174 micromolar for DIMBOA and a K(m) of 638 micromolar for DIBOA; the enzyme in peak 1 has a K(m) of 217 micromolar for DIMBOA and its activity on DIBOA was too low to determine a K(m). The identification of two glucosyltransferases capable of glucosylating hydroxamic acids in vitro serves as an initial step in the characterization of the enzymes involved in production of hydroxamic acids in maize.

Journal Article↗
PubMed1987

A behavioural and neurochemical analysis of chronic and selective monoamine oxidase inhibition.

The effects of clorgyline were compared with the effects of (-)-deprenyl using measures of rewarding hypothalamic self-stimulation, regional monoamine metabolism and monoamine oxidase activity. Male Wistar rats trained to self-stimulate at half-maximal rates with unilateral bipolar lateral hypothalamic electrodes on a continuous reinforcement schedule were implanted subcutaneously with osmotic minipumps which delivered 1 mg X kg-1 drug per day or vehicle for 13 days. A response rate/stimulation frequency (reward summation) function was determined the day before minipump implantation and on days 5 and 13 of drug administration. Only clorgyline induced a shift to the left in the reward summation function at 5 and 13 days, indicating enhancement of reinforcement. Clonidine (50 micrograms X kg-1 IP) probe tests were run on days 2 and 10 to determine the sensitivity of alpha 2-noradrenaline receptors. Clorgyline induced an attenuation of the clonidine response on day 10 relative to day 2. The other groups exhibited no change in response to clonidine. Clorgyline also induced a progressive increase in self-stimulation rates; this effect was not observed with the other groups. The clorgyline effects were accompanied by an increase in regional brain levels of dopamine, noradrenaline and 5-hydroxytryptamine and a reduction of their acid metabolites. Clorgyline selectively inhibited type A monoamine oxidase, whereas (-)-deprenyl selectively inhibited type B monoamine oxidase.

Animals↗
PubMed1987

In vivo release of endogenous dopamine, 5-hydroxytryptamine and some of their metabolites from rat caudate nucleus by phenylethylamine.

The in vivo release of endogenous 3,4-dihydroxyphenylethylamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 3-methoxytyramine (3-MT), and of 5-hydroxytryptamine (5-HT) and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), has been measured in the caudate nucleus of the anesthetized rat. A push-pull cannula was implanted into the brain, and the tissue perfused with artificial CSF or artificial CSF containing 5 X 10(-4) M phenylethylamine. The perfusate was collected and analyzed for DA, 5-HT and their metabolites by high performance liquid chromatography with electrochemical detection (HPLC-ECD). DA was released by phenylethylamine at rates significantly greater than its basal rate. 3-MT and 5-HT were undetectable in perfusates collected under basal conditions, but could be detected readily during phenylethylamine stimulation. DOPAC, HVA and 5-HIAA concentrations were not significantly affected by phenylethylamine. The results suggest (1) that phenylethylamine may exert its behavioural effects through increased release of both DA and 5-HT, and (2) that in vivo measurements of the acid metabolites alone may not be indicative of the release of the amines.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Choice of analog electronic low-pass filters in chromatography.

Butterworth low-pass filters, frequently used to improve signal-to-noise ratios in chromatographic instrumentation, are chosen for their frequency domain characteristics; their time domain response may introduce spurious peaks which are eliminated by use of the Bessel filter which provides improved chromatographic response.

Biogenic Amines↗
PubMed1986

New sensitive high-performance liquid chromatographic method for p-tyrosine aminotransferase assay.

A rapid, sensitive and specific procedure has been developed for the determination of p-tyrosine aminotransaminase activity. The assay is based on high-performance liquid chromatography (HPLC) separation and electrochemical detection of the pyruvate product, which has been derivatized with hydroxylamine to form a stable oxime. Using this method the product at the low pmol level can be measured. A comparison of the kinetic parameters of the rat liver tyrosine aminotransferase and rat brain non-specific aspartate aminotransferase towards p-tyrosine has been made.

Animals↗
PubMed1986

Stereospecific deuterium substitution at the alpha-carbon position of dopamine and its effect on oxidative deamination catalyzed by MAO-A and MAO-B from different tissues.

Stereospecific replacement of deuterium in the alpha-carbon side chain position of dopamine (DA) was achieved by decarboxylation of L-3,4-dihydroxyphenylalanine (L-dopa) using hog kidney aromatic aminoacid decarboxylase. The S[alpha-2H1]DA enantiomer was obtained by decarboxylation of L-[alpha-2H1]dopa in H2O, while the R[alpha-2H1]DA enantiomer was obtained by decarboxylation of unsubstituted L-dopa in 2H2O. An inverse solvent isotope effect of L-dopa decarboxylation was observed in 2H2O. The deaminated aldehyde products of the four DA analogues, i.e. undeuterated DA, [alpha, alpha-2H2] DA, R[alpha-2H1]DA and S[alpha-2H1]DA, have been analyzed by the gas chromatography-mass spectrometry (GC-MS) method. It is evident that monoamine oxidase (MAO) catalyzes the stereochemical removal of only R-deuterium and that S-deuterium was maintained at the alpha-carbon atom of 3,4-dihydroxyphenylacetaldehyde. The steady-state kinetics of the oxidative deamination of undeuterated, [alpha, alpha-2H2], R[alpha-2H1], and S[alpha-2H1] dopamine were assessed by determination of the aldehyde products directly by high performance liquid chromatography (HPLC) using electrochemical detection (ECD). MAO-A from rat liver mitochondria (deprenyl-treated) and from human placenta, as well as MAO-B from rat liver (clorgyline-treated) and from human platelet were used in this study. The apparent isotope effects, i.e. (V/K)H/(V/K)D ratios of [alpha, alpha-2H2]DA and R[alpha-2H1]DA, were quite similar (2.34 and 3.13) with respect to both MAO-A and MAO-B. S[alpha-2H1]DA exhibited a slight secondary isotope effect. Formula: see text.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

High-performance liquid chromatography of aldehydes and acids formed in monoamine oxidase-catalyzed reactions.

A rapid, sensitive, and specific method for the determination of monoamine oxidase (MAO) activities toward different substrates is described. The assay is based on high-performance liquid chromatographic (HPLC) separation and electrochemical detection of the aldehyde or acid products. The aldehyde metabolic intermediates were observed to be quite stable in 0.1 N perchloric acid containing antioxidant and EDTA, and therefore can be used to measure the MAO activity of washed mitochondrial membrane and partially purified or purified MAO. Incomplete conversion of aldehyde to acid was observed when the amine substrates were incubated with the crude enzyme preparations. These aldehydes can be converted to corresponding acids by addition of yeast aldehyde dehydrogenase and beta-NAD and the acid can also be measured by HPLC-electrochemical detection. A deuterium isotope effect in the oxidation of p-[alpha,alpha-2H2]tyramine and [alpha,alpha-2H2]serotonin has been demonstrated by this method.

Acids↗
PubMed1983

Rapid estimation of catecholamines, octopamine and 5-hydroxytryptamine in biological tissues using high-performance liquid chromatography with coulometric detection.

A rapid, convenient procedure is described for the simultaneous determination of catecholamines, monohydroxyphenolamines and 5-hydroxytryptamine in biological tissues. The procedure involves homogenization of tissue in perchloric acid, addition of heparin and centrifugation followed by direct injection of the supernatant onto a C18 reversed-phase high-performance liquid chromatographic column. The mobile phase employed sodium dodecyl sulfate as ion pair reagent with 20% acetonitrile and 10-12% methanol as organic modifier. Eluted fractions were detected electrochemically using dual coulometric electrodes operated in screen mode. The procedure has been applied to the analysis of norepinephrine, epinephrine, dopamine, octopamine, tyramine, 5-hydroxytryptamine and tryptophan in a variety of tissues including mammalian heart and brain and insect nerve cord.

Animals↗
PubMed1978

Line copy presentation slides with Kodalith.

Line copy presentation slides with white letters on a blue background can be produced with a two-step process. The slides are more permanent than diazo slides, and the process is faster and less expensive.

Ophthalmology↗
PubMed1975

The effect of an H2-receptor antagonist on food-stimulated acid secretion, serum gastrin, and gastric emptying in patients with duodenal ulcers. Comparison with an anticholinergic drug.

The purpose of the present series of experiments was to measure and compare the effects of an anticholinergic drug (isopropamide) and an antagonist of the histamine H2 receptor (metiamide) on food-stimulated acid secretion. Patients with duodenal ulcers were stimulated by a steak meal, and acid secretion was measured by in vivo intragastric titration. The largest dose of isopropamide that can be taken clinically without producing intolerable side effects (maximum tolerated dose) suppressed food-stimulated acid secretion by 35%. By contrast, metiamide in a 400-mg dose produced no side effects and almost completely abolished food-stimulated acid secretion. A dose-response curve revealed that a 50-mg dose of metiamide was required to suppress food-stimulated acid secretion by 50%. Further studies showed that metiamide and isopropamide are additive in suppressing food-stimulated acid secretion, and that metiamide has no effect on serum gastrin concentration or on gastric emptying.

Adult↗