High-Performance Liquid Chromatographic Analysis of Synthetic Peptides Using Derivatization with 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate

Antonis, Kathryn M. De; Brown, Phyllis R.; Cohen, Steven A.

doi:10.1006/abio.1994.1572

Cited by 33 publications

(7 citation statements)

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“…Serum levels of SAH and homocysteine were assayed by the method of Capdevila et al11 using the Axis Homocysteine Enzyme Immunoassay Kit (Axis‐Shield Diagnostics, Dundee, Scotland). The serum concentrations of SAM were assayed by reverse‐phase HPLC by a modified method of Wang et al12 Serum methionine levels were measured by the modified method of De Antonis et al13…”

Section: Methodsmentioning

confidence: 99%

Betaine for nonalcoholic fatty liver disease: Results of a randomized placebo-controlled trial

et al. 2009

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Based on animal studies and pilot studies in humans, betaine, a methyl donor for the remethylation of homocysteine, may be a therapeutic agent for nonalcoholic steatohepatitis (NASH). We evaluated the safety and efficacy of betaine for patients with NASH and whether betaine positively modified factors postulated to be "second hits" and underlying mechanisms of NASH. We conducted a randomized placebo-control study of 55 patients with biopsy-proven NASH who received either oral betaine (20 g daily) or placebo for 12 months. Pre-and posttreatment variables were analyzed using the paired t test or Wilcoxon rank test. Treatment groups were comparable at baseline. Of the 35 patients (17 betaine, 18 placebo) who completed the study, 34 patients (16 betaine, 18 placebo) underwent posttreatment liver biopsy. Patients randomized to betaine had a decrease in steatosis grade. No intra-or intergroup differences or changes in nonalcoholic fatty liver disease activity score or fibrosis stage were noted. Elevations of insulin, glucose, and proinflammatory cytokines and the reduced antioxidant status noted in NASH patients did not improve with betaine therapy. The antiinflammatory agent adiponectin was significantly reduced in both groups and did not change with therapy. Lastly, S-adenosylhomocysteine was approximately twice normal and was not reduced by betaine therapy. Conclusion: Compared to placebo, betaine improved hepatic steatosis and may protect against worsening steatosis. High-dose betaine supplementation failed to reduce S-adenosylhomocysteine and did not positively affect any of the second hit mechanisms postulated to contribute to NASH that we studied. Although betaine has been proven effective in treating hepatic steatosis in several animal models, translating novel therapeutic options noted in animal studies to humans with NASH will prove challenging.

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Section: Methodsmentioning

confidence: 99%

Betaine for nonalcoholic fatty liver disease: Results of a randomized placebo-controlled trial

et al. 2009

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“…Pure standards of ammonium, nitrate and nitrite were used to calculate their concentrations in the sugarcane sap. A total of 17 amino acids were separated by high-performance liquid chromatography (HPLC) and quantified by the fluorimetric detection of the 6-aminoquinolyl-N-hydroxy-succinimidyl carbamate derivatives using the Acc Qtag method (De Antonis and Brown, 1994).…”

Section: Analysesmentioning

confidence: 99%

Nitrogen compounds in the apoplastic sap of sugarcane stem: Some implications in the association with endophytes

Tejera

Ortega

Rodés

et al. 2006

Journal of Plant Physiology

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“…Glutamate, aspartate, and citrulline assay Glutamate, aspartate, and citrulline concentrations were measured using 6-aminoquinolyl-N-hydroxysuccinimidyl carbonate (AQC) derivatization and a high-performance liquid chromatography (HPLC)/mass spectroscopy assay modified from DeAntonis et al 23 and Cohen et al 24 Briefly, the derivatizing reagent, AQC, was synthesized according to the method of Cohen et al…”

Section: Drug Administrationmentioning

confidence: 99%

Effect of postinjury intravenous or intrathecal methylprednisolone on spinal cord excitatory amino-acid release, nitric oxide generation, PGE2 synthesis, and myeloperoxidase content in a pig model of acute spinal cord injury

Bernards

Akers

2006

Spinal Cord

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Objectives: To determine whether postinjury methylprednisolone could reduce the generation of known mediators of secondary neurological injury. Methods: Intrathecal microdialysis probes were used to sample cerebrospinal fluid (CSF) for measurement of PGE 2 , glutamate, and citrulline (a byproduct of nitric oxide generation), before and after spinal cord injury in anesthetized pigs. The spinal cord was removed at the end of the study for measurement of myeloperoxidase and methylprednisolone concentrations. Animals were randomly allocated to receive intravenous methylprednisolone (30 mg/kg bolus then 3.4 mg/kg/h), intrathecal methylprednisolone (5 mg bolus then 5 mg/h), or saline, beginning 30 min after the spinal cord was injured by using a modification of the Allen weight drop technique. Results: Spinal cord injury significantly increased the amount of glutamate, PGE 2 , myeloperoxidase, and citrulline, recovered from the CSF dialysates. However, neither intravenous nor intrathecal methylprednisolone administered after injury had any effect on the magnitude of the increase in any of the measured biochemicals. Intrathecal methylprednisolone administration produced a spinal cord methylprednisolone concentration that was eight times greater, and a plasma concentration that was 32 times less, than that achieved with intravenous administration. Conclusions: Contrary to earlier animal studies in which methylprednisolone was administered either before or immediately after spinal cord injury, we found no effect of intravenous or intrathecal methylprednisolone on any of the parameters measured when administered 30 min postinjury.

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High-Performance Liquid Chromatographic Analysis of Synthetic Peptides Using Derivatization with 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate

Cited by 33 publications

References 0 publications

Betaine for nonalcoholic fatty liver disease: Results of a randomized placebo-controlled trial

Betaine for nonalcoholic fatty liver disease: Results of a randomized placebo-controlled trial

Nitrogen compounds in the apoplastic sap of sugarcane stem: Some implications in the association with endophytes

Effect of postinjury intravenous or intrathecal methylprednisolone on spinal cord excitatory amino-acid release, nitric oxide generation, PGE2 synthesis, and myeloperoxidase content in a pig model of acute spinal cord injury

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