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Biomedical subjects

N D Brown

Publications and source records attributed to N D Brown.

At least 37 records · Page 2Linked to original sources
PubMed1985

Unexpected increase in catecholamines in adrenals of rats treated with 3-deazaadenosine.

Using electrochemical detection, 3-deazaadenosine, a proximal inhibitor of methylation via the inhibition of S-adenosylhomocysteine hydrolase, perturbed the metabolism of catecholamines in the adrenals of rats. In adrenals of rats treated with 3-deazaadenosine, both norepinephrine and epinephrine increased significantly by about two-fold. 3-Deazaadenosine may inhibit the release of catecholamines from the adrenals by affecting membrane functions of the adrenals.

Adenosylhomocysteinase↗
PubMed1985

Ornithine decarboxylase inhibition and the malaria-infected red cell: a model for polyamine metabolism and growth.

The addition of DL-alpha-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, to human Plasmodium falciparum-infected red cells in continuous culture decreased both parasite growth and intracellular polyamine concentrations. Growth of P. falciparum in infected red cells was assessed by parasite counts and by assays for macromolecular syntheses of protein, DNA and RNA. Polyamine concentrations were measured by an automated high-performance liquid chromatography method. Concentrations of DL-alpha-difluoromethylornithine greater than 0.3 mM decreased intracellular levels of putrescine and spermidine, reduced ornithine decarboxylase activity and inhibited growth and maturation of the intracellular parasite at the trophozoite stage. There was a concomitant decrease in the synthesis of protein and nucleic acids in the infected cells. The use of this parasitized red cell model system together with polyamine inhibitors provide means of studying polyamine synthesis and cell growth in the design of new antimalarial therapy.

Cells, Cultured↗
PubMed1984

Mediastinal pancreatic pseudocyst.

Among previous cases of mediastinal pseudocyst requiring surgical decompression, all but one had been found at surgery to occupy a position both in the mediastinum and in the upper abdomen. In the present case, although preoperative ultrasound and CT scans suggested that the pseudocyst was straddling the diaphragm, an abdominal portion could not be found at surgery, and the pseudocyst was drained successfully through the diaphragm by a Roux-en-Y loop of jejunum. Because ultrasound and CT scan may not be able to determine the precise relationship of a mediastinal pseudocyst to the diaphragm and the availability of the lower portion of the pseudocyst for surgical decompression, an endoscopic retrograde cholangiopancreatography is strongly recommended as part of the preoperative evaluation.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1983

Inhibition of adenosylmethionine decarboxylase and perturbation of polyamine metabolism by 3-deaza-(+/-)aristeromycin.

3-Deaza-(+/-)aristeromycin, previously known mainly as a potent inhibitor of adenosylhomocysteine hydrolase, can also inhibit the activity of adenosylmethionine decarboxylase. The release of [14C]CO2 from HeLa cells labeled with [carboxyl-14C]methionine was inhibited by more than 70% after 4 hours in the presence of 4 microM 3-deaza-(+/-)aristeromycin. Concomitant with this inhibition, there was a significant increase in the amount of putrescine in the HeLa cells. Adenosylmethionine decarboxylase isolated from HeLa cells could also be inhibited by 3-deaza-(+/-)aristeromycin and 3-deazaadenosine, 3-deazaadenosylhomocysteine, and 3-deaza-(+/-)aristeromycinylhomocysteine.

Adenosine↗
PubMed1982

Femtomolar ion-pair high-performance liquid chromatographic method for determining Dns-polyamine derivatives of red blood cell extracts utilizing an automated polyamine analyzer.

An ultra-sensitive automated method for the determination of polyamines in red blood cell extracts by ion-pair reversed-phase high-performance liquid chromatography is described. The 5-dimethylaminonaphthalene-1-sulfonyl derivatives of putrescine, 1,6-diaminohexane, spermidine, and spermine are separated on a muBondapak C18 column using 1-heptanesulfonic acid and acetonitrile as the mobile phase. All compounds are eluted within 28 min subsequent to the initial injection. The method has a lower detection limit of 25 fmoles on column. Because of the simplicity and ease of operation, the method is applicable for use in either the research or clinical laboratory.

Chromatography, High Pressure Liquid↗
PubMed1979

Determination of 5-dimethylaminonaphthalene-1-sulfonyl derivatives of urinary polyamines by ion-pair high-performance liquid chromatography.

A sensitive and specific method for the determination of diamines and polyamines by ion-pair high-performance liquid chromatography is described. The 5-dimethylaminonaphthalene-1-sulfonyl derivatives of putrescine, 1,6-diaminohexane, spermidine and spermine are separated on a muBondapak C18 reversed-phase column with 1-heptanesulfonic acid and acetonitrile as the mobile phase. All compounds are eluted within 30 min using a programmed solvent gradient system. The method has a lower detection limit of 1 pmole on column. Because of the simplicity of the method, its application provides a better means for closely monitoring patients undergoing treatment for various types of genito-urinary neoplastic diseases.

Chromatography, High Pressure Liquid↗
PubMed1978

Ion-pair high-performance liquid chromatographic separation of a multicomponent anticholinergic drug formulation.

N,N'-Trimethylene-bis-(pyridinium-4-aldoxime)dibromide, 4-pyridine aldoxime, atropine sulfate, benactyzine hydrochloride, methyl paraben and propyl paraben are separated by ion-pair high-performance liquid chromatography. The method is specific for detecting and quantifying each compound in a complex mixture without solvent extraction or pretreatment. Levels as low as 1 ng on column are quantifiable by the procedure. All components are eluted within 9 min subsequent to the initial injection. Because of the simplicity of the method, the procedure is suitable for routinely monitoring the stability of the various compounds in the formulation during storage.

Atropine↗
PubMed1977

Determination of "true" serum creatinine by high-performance liquid chromatography combined with a continuous-flow microanalyzer.

We coupled a high-performance liquid chromatograph with a continuous-flow microanalyzer to produce a system for specifically determinig "true" creatinine in urine and serum specimens. A selective microbore pellicular cation-exchange column and a single eluting sodium citrate buffer are used to separate the noncreatinine but Jaffé-positive constituents from the creatinine in normal and experimental specimens. The effluent is analyzed continuously, on-line, the alkaline picrate complex being developed and measured in the microanalyzer. Physiological samples, reference standards, and internal control specimens are assayed in 6-min intervals subsequent to the initial injection. The relationship between concentration and peak are is linear for creatinine standards between 5 and 10 mg/liter. Specimen volumes ranging from 1 to 25 microliters, and containing creatinine in amounts exceeding 5 ng per injected sample, can be assayed with this system.

Chromatography, High Pressure Liquid↗
PubMed1976

A study of the Bratton and Marshall hydrolysis procedure utilizing high performance liquid chromatography.

Most analytical methods for conjugated aromatic amines require hydrolysis to free the amine group. The rate of conversion of N-acetyl-p-aminohippuric acid to its deacetylated and deglycinated derivatives is directly related to the hydrolysis reaction time and the concentration of hydrochloric acid used in the reaction. Variations in methodology involving either of these hydrolysis parameters produced artifacts which were not detectable by the standard colorimetric procedures. High performance liquid chromatography offers an improved tool for detecting and quantitating the changes produced during hydrolysis.

Amines↗