Nesbitt D. Brown

Femtomolar ion-pair high-performance liquid chromatographic method for determing 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.

Hydroxychloroquine in human breast milk

SummaryHydroxychloroquine 3.2 µg was detected in breast milk from a woman given 800 mg over 48 hour.

The metabolism of choline by the germfree rat

Abstract Choline chloride, administered intragastrically to normal rats (200 mg./kg. body weight) gave rise to urinary total trimethylamines (TTMA) in yields of 10–66.2% of the administered dose. However, germfree rats given the same dose of choline chloride excreted an average of only 0.6% of the choline as TTMA. Feeding of choline chloride to conventional rats on four successive days gave rise to a daily TTMA excretion comparable with those fed only once; germfree rats fed this way, excreted only a trace of TTMA on any of the 4 days. Neither the conventional nor the germfree rats excreted more than a trace of choline in the urine under any conditions, nor was urinary creatinine affected by choline feeding. On the other hand, ingested trimethylamine was quantitatively excreted by both groups. Tracer studies carried out with methyl-labeled choline-C 14 , showed that labeled urinary TTMA was excreted only when large doses of unlabeled choline were fed with the tracer. The conclusion is drawn that the formation of urinary trimethylamine from choline is brought about by microbial enzymes.

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.

high-performance liquid chromatographic method for the determination ofp-aminobenzoic acid and some of its metabolites

Abstract The development of a relatively simple high-performance liquid chromatographic method for the anlysis of p -aminobenzoic acid and some of its metabolites is reported. The method is specific for detecting and quantifying p -aminohippuric acid. Urine and serum samples can be analyzed directly withou solvent extraction or pretreatment. The method has a lower detection limit of 5 ng on column. All the compounds are eluted within 20 min. The method is suitable for routine clinical determinations.

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.

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.

Stabilization of thymopentin and preservation of its pharmacological properties by 2-hydroxypropyl-β-cyclodextrin

Abstract— Thymopentin prepared in 5, 15, and 20% 2‐hydroxypropyl‐β‐cyclodextrin (HPCD) was able to inhibit guinea‐pig ileum contraction stimulated by anatoxin‐a (3 × 10−6 m) after fourteen months of storage at room temperature. Thus, in contrast to the instability of thymopentin prepared without HPCD, the pharmacological activity was retained and could be stored in a ready‐to‐use solution for extended periods without refrigeration.

Induction of Differentiation of 3T3-L1 Fibroblasts to Adipocytes by 3-Deazaadenosine and Insulin

3-Deazaadenosine (dzAdo), an analog of adenosine, is a potent proximal inhibitor of S-adenosylmethionine-dependent transmethylation reactions (1–3). A variety of transmethylation reactions have been shown to be inhibited by dzAdo because of its ability to act as an alternative substrate and also as an inhibitor of S-adenosylhomocysteine hydrolase, which hydrolyzes S-adenosylhomocysteine to adenosine and L-homocysteine. A unique feature of S-adenosylhomocysteine hydrolase is that it can synthesize a novel S-nucleosidylhomocysteine analog by condensing a nucleoside with L-homocysteine because the equilibrium of the reaction favors the synthetic direction (1–5). When dzAdo is administered to cells or animals, the net result is the accumulation of S-adenosylhomocysteine and S-3-deazaadenosylhomocysteine, both of which are known potent inhibitors of transmethylation reactions (6–11).

Disposition of aprophen in rats

The pharmacokinetics of [14C]aprophen and its distribution were determined after intravenous administration to rats. The drug was distributed rapidly with a t½ (α) of 4 min to highly perfused organs like the brain, kidney and adrenals. An elimination phase was apparent 10 min after injection with a t½ (β) of 23.5 min. The high plasma clearance of the drug was due both to a large volume of distribution and to a high metabolic rate. Aprophen could be hydrolysed to diphenylpropionic acid and diethylaminoethanol in‐vivo and in‐vitro. Diethylaminoethanol competed with [3H]QNB binding to muscarinic receptors of N4TG1 cells, whereas diphenylpropionic acid did not. The lower plasma concentrations and lower binding activity of diethylaminoethanol compared with aprophen indicate that unchanged aprophen is largely responsible for the in‐vivo actions.