Atmospheric pressure chemical ionization-mass spectrometry method to improve the determination of dansylated polyamines

Fentanyl-induced hyperalgesia and analgesic tolerance in male rats: common underlying mechanisms and prevention by a polyamine deficient diet

Opioids are a mainstay of pain management but can induce unwanted effects, including analgesic tolerance and paradoxical hyperalgesia, either of which leads to increased pain. Clinically, however, the relationship between these two phenomena remains elusive. By evaluating changes in mechanical nociceptive threshold in male rats, we found that in contrast to a purely analgesic control response to a single subcutaneous administration of fentanyl (25 μg/kg), in rats subjected to inflammatory pain 2 weeks previously (Day₀), the same test dose (D₁₃) induced a bi-phasic response: initial decreased analgesia (tolerance) followed by hyperalgesia lasting several hours. Both the tolerance and hyperalgesia were further enhanced in rats that had additionally received fentanyl on D₀. The dose-response profiles (5 fg to 50 μg/kg) of pain- and opioid-experienced rats were very different from pain/drug-naive rats. At ultra-low fentanyl doses (<5 ng/kg and <500 ng/kg for naïve control and pain/drug-experienced rats, respectively), solely hyperalgesia was observed in all cases. At higher doses, which now produced analgesia alone in naive rats, reduced analgesia (tolerance) coupled with hyperalgesia occurred in pain/fentanyl-experienced rats, with both phases increasing with dose. Transcriptomic and pharmacological data revealed that an overactivation of the spinal N-methyl-_D-aspartate receptor-inducible NO synthase cascade plays a critical role in both acute tolerance and hyperalgesia, and together with the finding that the magnitudes of analgesia and associated hyperalgesia are negatively correlated, is indicative of closely related phenomena. Finally, a polyamine deficient diet prevented inducible NO synthase transcript upregulation, restored fentanyl's analgesic efficacy and suppressed the emergence of hyperalgesia.

Gender-Related Differences on Polyamine Metabolome in Liquid Biopsies by a Simple and Sensitive Two-Step Liquid-Liquid Extraction and LC-MS/MS

Polyamines are involved in the regulation of many cellular functions and are promising biomarkers of numerous physiological conditions. Since the concentrations of these compounds in biological fluids are low, sample extraction is one of the most critical steps of their analysis. Here, we developed a comprehensive, sensitive, robust, and high-throughput LC-MS/MS stable-isotope dilution method for the simultaneous determination of 19 metabolites related to polyamine metabolism, including polyamines, acetylated and diacetylated polyamines, precursors, and catabolites from liquid biopsies. The sample extraction was optimized to remove interfering compounds and to reduce matrix effects, thus being useful for large clinical studies. The method consists of two-step liquid-liquid extraction with a Folch extraction and ethyl acetate partitioning combined with dansyl chloride derivatization. The developed method was applied to a small gender-related trial concerning human serum and urine samples from 40 obese subjects. Sex differences were found for cadaverine, putrescine, 1,3-diaminopropane, γ-aminobutyric acid, N8-acetylspermidine, and N-acetylcadaverine in urine; N1-acetylspermine in serum; and spermine in both serum and urine. The results demonstrate that the developed method can be used to analyze biological samples for the study of polyamine metabolism and its association with human diseases.

Quantification of free polyamines and their metabolites in biofluids and liver tissue by UHPLC-MS/MS: application to identify the potential biomarkers of hepatocellular carcinoma

Polyamines and their N-acetylated metabolites are potential biomarkers in the diagnosis and therapeutic evaluation of cancer. Thus, we present here an ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of 6 free, 3 monoacetylated, and 2 diacetylated polyamines without derivatization. The major improvement of this method is the use of 0.2 % perfluoroheptanoic acid methanol in the pretreatment step to achieve protein precipitation and 0.0125 % perfluoroheptanoic acid in the mobile phase to achieve analyte separation within 9 min. The established analytical method was validated with plasma, urine, and liver tissue and applied to determine plasma, urine, and liver tissue samples from healthy rats, hepatocellular carcinoma rats, and administrated rats successfully. Results indicated free polyamines such as putrescine mainly existed in liver tissue but more polar N-acetylated metabolites such as N (1),N (12)-diacetylspermine seemed to exist in biological fluid. After carcinogenesis, the levels of polyamines were increased, but the elevated levels of polyamines and their metabolites tended to decrease when administrated with anticancer drug. The method provided a more versatile manner for clinical application in the diagnosis and therapeutic evaluation of hepatocellular carcinoma.

Cucurbit[6]uril is an ultrasensitive (129)Xe NMR contrast agent

A lack of molecular contrast agents has slowed the application of ultrasensitive hyperpolarized (129)Xe NMR methods. Here, we report that commercially available cucurbit[6]uril (CB[6]) undergoes rapid xenon exchange kinetics at 300 K, and is detectable by Hyper-CEST NMR at 1.8 pM in PBS and at 1 μM in human plasma where many molecules, including polyamines, can compete with xenon for CB[6] binding.

A polyamine-deficient diet prevents oxaliplatin-induced acute cold and mechanical hypersensitivity in rats

Background

Oxaliplatin is an anticancer drug used for the treatment of advanced colorectal cancer, but it can also cause painful peripheral neuropathies. The pathophysiology of these neuropathies has not been yet fully elucidated, but may involve spinal N-methyl-D-aspartate (NMDA) receptors, particularly the NR2B subunit. As polyamines are positive modulators of NMDA-NR2B receptors and mainly originate from dietary intake, the modulation of polyamines intake could represent an interesting way to prevent/modulate neuropathic pain symptoms by opposing glutamate neurotransmission.

Methods

The effect of a polyamine deficient diet was investigated in an animal model of oxaliplatin-induced acute pain hypersensitivity using behavioral tests (mechanical and cold hypersensitivity). The involvement of spinal glutamate neurotransmission was monitored by using a proton nuclear magnetic resonance spectroscopy based metabolomic approach and by assessing the expression and phosphorylation of the NR2B subunit of the NMDA receptor.

Results

A 7-day polyamine deficient diet totally prevented oxaliplatin-induced acute cold hypersensitivity and mechanical allodynia. Oxaliplatin-induced pain hypersensitivity was not associated with an increase in NR2B subunit expression or phosphorylation, but with an increase of glutamate level in the spinal dorsal horn which was completely prevented by a polyamine deficient diet. As a validation that the oxaliplatin-induced hypersensitivity could be due to an increased activity of the spinal glutamate system, an intrathecal administration of the specific NR2B antagonist, ifenprodil, totally reversed oxaliplatin-induced mechanical and cold hypersensitivity.

Conclusion

A polyamine deficient diet could represent a promising and valuable nutritional therapy to prevent oxaliplatin-induced acute pain hypersensitivity.

Determination of polyamine metabolome in plasma and urine by ultrahigh performance liquid chromatography-tandem mass spectrometry method: application to identify potential markers for human hepatic cancer

To evaluate the potential relationship between cancer and polyamine metabolome, a UHPLC-MS/MS method has been developed and validated for simultaneous determination of polyamine precursors, polyamines, polyamine catabolite in human plasma and urine. Polyamine precursors including L-ornithine, lysine, L-arginine and S-adenosyl-L-methionine; polyamines including 1,3-diaminopropane, putrescine, cadaverine, spermidine, spermine, agmatine, N-acetylputrescine, N-acetylspermine and N-acetylspermidine; polyamine catabolite including γ-aminobutyric acid had been determined. The analytes were extracted from plasma and urine samples by protein precipitation procedure, and then separated on a Shim-pack XR-ODS column with 0.05% heptafluorobutyric acid (HFBA) in methanol and 0.05% HFBA in water. The detection was performed on UHPLC-MS/MS system with turbo ion spray source in the positive ion and multiple reaction-monitoring mode. The limits of quantitation for all analytes were within 0.125-31.25 ng mL(-1) in plasma and urine. The absolute recoveries of analytes from plasma and urine were all more than 50%. By means of the method developed, the plasma and urine samples from hepatic cancer patients and healthy age-matched volunteers had been successfully determined. Results showed that putrescine and spermidine in hepatic cancerous plasma were significant higher than those in healthy ones, while spermidine, spermine and N-acetylspermidine in hepatic cancerous urine were significant higher than those in healthy ones. The methods demonstrated the changes of polyamine metabolome occurring in plasma and urine from human subjects with hepatic cancer. It could be a powerful manner to indicate and treat hepatic cancer in its earliest indicative stages.

A polyamine-deficient diet opposes hyperalgesia, tolerance and the increased anxiety-like behaviour associated with heroin withdrawal in rats

In humans, hyperalgesia, tolerance and anxiety disorders are common symptoms during heroin withdrawal syndrome. Significant evidence supports a role of NMDA receptors in these phenomena. Because polyamines may positively modulate the functioning of NMDA receptors and mainly originate from dietary intake, one hypothesis is that a polyamine deficient diet (PD diet) may reduce withdrawal symptoms. To address this question, we investigated the ability of a PD diet to prevent or to alleviate some symptoms of withdrawal syndrome as hyperalgesia, and increased anxiety-like behaviour in rats receiving 14 once daily subcutaneous heroin injections. Here, we show that a PD diet has both preventive and curative properties for reducing certain signs of withdrawal such as hyperalgesia, tolerance and increased anxiety-like behaviour observed in rats fed with a standard diet. Moreover, in heroin-withdrawn rats which were returned to basal pain sensitivity level, hyperalgesia following acute analgesia induced by a single heroin dose was observed in heroin-treated rats fed with standard diet, not in rats fed with a PD diet. Similarly, a stress-induced hyperalgesia induced by a non-nociceptive environmental stress session was observed in heroin-treated rats fed with standard diet. In contrast, a stress-induced analgesia was observed in heroin-treated rats fed with a PD diet, as it was observed in non heroin-treated rats. Since a PD diet for several weeks did not induce appreciable side-effects in rats, these preclinical results suggest that a PD diet could be an effective strategy for improving the relief of certain negative emotional states of heroin withdrawal syndrome and to allow reducing other medications generally used, such as opioid maintenance drugs.

Determination of polyamines in human plasma by high-performance liquid chromatography coupled with Q-TOF mass spectrometry

A high-performance liquid chromatography coupled with Q-time of flight mass spectrometry (HPLC/Q-TOF MS) method was developed and validated for the determination of 1, 3-diaminopropane, putrescine, cadaverine, spermidine and spermine in human plasma. The plasma samples were first pretreated by 10% HClO(4) and then derived by benzoyl chloride with 1, 6-diaminohexane as internal standard. The derived polyamines were separated on a C(18) column using a gradient program. The detection was performed on a Q-TOF MS by positive ionization mode. Calibration curve for each polyamine was obtained in the concentration range of 0.4 ~ 200.0 ng • ml(-1), with limit of detection of 0.02 ~ 0.1 ng • ml(-1). The intra- and inter-day RSD for all polyamines were 2.5-14.0% and 2.9 ~ 13.4%, respectively. The method was applied to determine the polyamines in human plasma from cancer patients and healthy volunteers. Results showed that the mean levels of polyamines in the plasma of cancer patients were higher than that of healthy volunteers, which suggested that the plasma polyamines could be employed as cancer diagnostic indicators in clinical testing.

N-Carbamoylputrescine, a citrulline-derived polyamine, is not a significant citrulline metabolite in rats

Citrulline, a key amino acid of the urea cycle, has been shown to play a regulatory role in protein and energy metabolism in mammals. We questioned whether N-carbamoyl-putrescine (NCP), the decarboxylated derivative of citrulline, could play a role in the biological properties of this amino acid. To evidence the presence of NCP in mammalian tissues, we developed a sensitive reverse-phase high-performance liquid chromatography (HPLC) with fluorimetric detection method with precolumn dansyl derivatization and solid-phase extraction for the determination of NCP together with polyamines in biological samples. Dansyl NCP was identified with a 5.85-min retention time. Linearity was obtained in a concentration range of 0.125 to 12.5 μM. Intraday and day-to-day relative coefficients of variation ranged from 8.9% to 12.3% and from 14% to 14.3%, respectively. Recovery rates in serum ranged from 75% to 83%. Thereafter, we used this method to search for the presence of NCP in serum, muscle, liver, jejunum, and ileum in rats after both short-term intraperitoneal injection and long-term oral citrulline supplementation. We failed to detect NCP in these animals. These data suggest that NCP is not a significant citrulline metabolite in rats.

Enhancement of the capabilities of liquid chromatography-mass spectrometry with derivatization: general principles and applications

The integration of liquid chromatography-mass spectrometry (LC-MS) with derivatization is a relatively new and unique strategy that could add value and could enhance the capabilities of LC-MS-based technologies. The derivatization process could be carried out in various analytical steps, for example, sampling, storage, sample preparation, HPLC separation, and MS detection. This review presents an overview of derivatization-based LC-MS strategy over the past 10 years and covers both the general principles and applications in the fields of pharmaceutical and biomedical analysis, biomarker and metabolomic research, environmental analysis, and food-safety evaluation. The underlying mechanisms and theories for derivative reagent selection are summarized and highlighted to guide future studies.

The effect of experimental conditions on the detection of spermine in cell extracts and tissues

The aim of this work was to investigate the effect of experimental conditions on the visibility of polyamines. In solution the chemical shift of the three groups of peaks (at approximately 1.8, 2.1 and 3.1 ppm) were found to be pH dependent. Relaxation times in aqueous solution at pH 7.0, 298 K and 11.74 T were measured to be: putrescine (T(1) = 2.49 s, T(2) = 2.07 s), spermidine (T(1) = 1.27 s, T(2) = 1.05 s) and spermine (T(1) = 1.02 s, T(2) = 0.82 s). Simple spin-echo sequences could not be used to measure T(2) as the spins also experience phase evolution from homonuclear coupling which imposes a modulation on the T(2) decay curve. This modulation is eliminated by using CPMG sequences with an echo spacing of <500 micros. Relaxation times for spermine in solution in presence of metal ions and protein showed that metal ions had little effect on T(2); however, addition of 15 mg/ml bovine serum albumin reduced T(2) of spermine (0.41 s at 298 K and 0.19 s at 277 K) but was not as short as the T(2) of the polyamine peak in prostatic tissue (0.03 s at 277 K). The MR visibility of polyamines in prostate cell extracts, PC-3 xenograft (intact as well as extracted) and intact human prostatic tissues were investigated. Polyamines were not detected in methanol/chloroform extracts, but were visible in perchloric acid extracts of prostate tumour cells. No polyamines were detected in the HR MAS spectra of three samples of whole PC-3 xenograft tissue studied. In summary, the chemical shift of polyamine species is pH dependent, while protein binding causes peak broadening and reduction in T(2). Perchloric acid extraction improves visibility of intracellular polyamines, but whole tissue polyamines are not seen in xenografts without epithelial/ ductal structure.

Determination of dansylated polyamines in red blood cells by liquid chromatography-tandem mass spectrometry

The concentration of polyamines in red blood cells (RBCs) is considered to be an index of cell proliferation. This index has been demonstrated to be of clinical importance for the follow-up and treatment of some cancer patients. The concentration of polyamines in RBCs is usually determined by high-performance liquid chromatography (HPLC) with fluorescence detection. In the current work, we present a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of putrescine, spermidine, and spermine, the three major polyamines in RBCs. The polyamines were dansylated and analyzed by an LC gradient of 20-min duration on a C18 column on-line with a tandem mass spectrometer. An internal standard (1,8-diaminooctane) was used for quantification. This method exhibited excellent linearity for the three polyamines with regression coefficients higher than 0.99. The limits of detection for putrescine, spermidine, and spermine were 0.10, 0.75, and 0.50 pmol/ml, respectively. The intrarun precision values for putrescine, spermidine, and spermine all were better than 10%, and the interrun precision values were 13%, 9%, and 20%, respectively. The LC-MS/MS method is sufficiently simple and reliable enough to replace the currently used HPLC method with fluorescence detection in which putrescine is not always detectable.

Crenarchaeal arginine decarboxylase evolved from an S-adenosylmethionine decarboxylase enzyme

The crenarchaeon Sulfolobus solfataricus uses arginine to produce putrescine for polyamine biosynthesis. However, genome sequences from S. solfataricus and most crenarchaea have no known homologs of the previously characterized pyridoxal 5'-phosphate or pyruvoyl-dependent arginine decarboxylases that catalyze the first step in this pathway. Instead they have two paralogs of the S-adenosylmethionine decarboxylase (AdoMetDC). The gene at locus SSO0585 produces an AdoMetDC enzyme, whereas the gene at locus SSO0536 produces a novel arginine decarboxylase (ArgDC). Both thermostable enzymes self-cleave at conserved serine residues to form amino-terminal beta-domains and carboxyl-terminal alpha-domains with reactive pyruvoyl cofactors. The ArgDC enzyme specifically catalyzed arginine decarboxylation more efficiently than previously studied pyruvoyl enzymes. alpha-Difluoromethylarginine significantly reduced the ArgDC activity of purified enzyme, and treating growing S. solfataricus cells with this inhibitor reduced the cells' ratio of spermidine to norspermine by decreasing the putrescine pool. The crenarchaeal ArgDC had no AdoMetDC activity, whereas its AdoMetDC paralog had no ArgDC activity. A chimeric protein containing the beta-subunit of SSO0536 and the alpha-subunit of SSO0585 had ArgDC activity, implicating residues responsible for substrate specificity in the amino-terminal domain. This crenarchaeal ArgDC is the first example of alternative substrate specificity in the AdoMetDC family. ArgDC activity has evolved through convergent evolution at least five times, demonstrating the utility of this enzyme and the plasticity of amino acid decarboxylases.

Analysis of underivatized polyamines by reversed phase liquid chromatography with electrospray tandem mass spectrometry

A reversed phase liquid chromatography-electrospray ionization-tandem mass spectrometric method (RP-LC-ESI-MS/MS) was developed to separate and detect polyamines with minimal sample pre-treatment and without any derivatization. Prior to MS/MS analysis, a complete chromatographic separation of polyamines was achieved by a linear gradient elution using heptafluorobutyric acid as a volatile ion-pair modifier, and signal suppression was prevented by post-column addition of 75% propionic acid in isopropanol to the column flow. The developed method was successfully applied to the identification of metabolites formed from N(1),N(12)-diethylspermine in the reaction catalyzed by recombinant human polyamine oxidase and to the detection of eight different polyamines in a standard mixture.

Antiproliferative and apoptotic effects in rat and human hepatoma cell cultures of the orally active iron chelator ICL670 compared to CP20: a possible relationship with polyamine metabolism

OBJECTIVE

Iron loading has been observed to have a hyperproliferative effect on hepatocytes in vitro and on tumour cells in vivo; removal of this iron being required to induce antitumour activity.

MATERIAL AND METHODS

Antiproliferative effects of orally active tridentate iron chelator ICL670 (deferasirox) and bidentate iron chelator CP20 (deferiprone), mediated through the chelation of intracellular iron, were compared in rat hepatoma cell line FAO and human hepatoma cell line HUH7.

RESULTS

In FAO cell cultures, we have shown that ICL670 decreased cell viability and DNA replication and induced apoptosis more efficiently than an iron-binding equivalent concentration of CP20. Moreover, ICL670 decreased significantly the number of the cells in G(2)-M phase. In the HUH7 cell cultures, ICL670 and a four-time higher iron-binding equivalent concentration of CP20, decreased cell viability and DNA replication in the same range. CP20 increased the number of the cells in G(2)-M phase. However, ICL670 inhibited polyamine biosynthesis by decreasing ornithine decarboxylase mRNA level; in contrast, CP20 increased polyamine biosynthesis, particularly putrescine level, by stimulating spermidine-spermine N(1)-acetyl transferase activity that could activate the polyamine retro-conversion pathway. By mass spectrometry, we observed that ICL670 cellular uptake was six times higher than CP20.

CONCLUSIONS

These results suggest that ICL670 has a powerful antitumoural effect and blocks cell proliferation in neoplastic cells by a pathway different from that of CP20 and may constitute a potential adjuvant drug for anticancer therapy.

Polyamine deficient diet to relieve pain hypersensitivity

There is a compelling body of evidence that N-methyl-d-aspartate receptors (NMDA-R) play a critical role in the development and maintenance of pain hypersensitivity. However, long-term treatments with NMDA-R antagonists are limited by unacceptable side effects. Since polyamines modulate the functioning of NMDA-R and mainly originate from normal dietary intake and bacterial metabolism in the gut, we developed a nutritional therapy based on dietary polyamine deficiency. Here, we reported that a polyamine deficient diet (PD diet) for 7 days prevented the enhancement of tyrosine phosphorylation of the spinal NR2B subunit-containing NMDA-R associated with inflammation in rats. Based on these data, we studied the ability of PD diet to prevent long-lasting pain hypersensitivity associated with tissue injury on one hind paw by evaluating long-lasting changes in both mechanical nociceptive threshold and weight bearing. A PD diet strongly reduced long-lasting hyperalgesia induced by inflammation or incision, especially in fentanyl-treated rats. Moreover a PD diet also prevented the exaggerated hyperalgesia induced by a second inflammation performed 7 days after the first one. A PD diet also opposed paradoxical hyperalgesia induced by non-nociceptive environmental stress in rats with pain and opioid experiences. A PD diet reversed pain hypersensitivity associated with monoarthritis or neuropathy and restored the analgesic effect of morphine. Since PD diet was devoid of any noticeable side effects, this nutritional therapy could be part of an effective and safe strategy for pre-emptive analgesia and for reducing the transition from acute to chronic pain and its outcomes in various pain syndromes.

The first agmatine/cadaverine aminopropyl transferase: biochemical and structural characterization of an enzyme involved in polyamine biosynthesis in the hyperthermophilic archaeon Pyrococcus furiosus

We report here the characterization of the first agmatine/cadaverine aminopropyl transferase (ACAPT), the enzyme responsible for polyamine biosynthesis from an archaeon. The gene PF0127 encoding ACAPT in the hyperthermophile Pyrococcus furiosus was cloned and expressed in Escherichia coli, and the recombinant protein was purified to homogeneity. P. furiosus ACAPT is a homodimer of 65 kDa. The broad substrate specificity of the enzyme toward the amine acceptors is unique, as agmatine, 1,3-diaminopropane, putrescine, cadaverine, and sym-nor-spermidine all serve as substrates. While maximal catalytic activity was observed with cadaverine, agmatine was the preferred substrate on the basis of the k(cat)/K(m) value. P. furiosus ACAPT is thermoactive and thermostable with an apparent melting temperature of 108 degrees C that increases to 112 degrees C in the presence of cadaverine. Limited proteolysis indicated that the only proteolytic cleavage site is localized in the C-terminal region and that the C-terminal peptide is not necessary for the integrity of the active site. The crystal structure of the enzyme determined to 1.8-A resolution confirmed its dimeric nature and provided insight into the proteolytic analyses as well as into mechanisms of thermal stability. Analysis of the polyamine content of P. furiosus showed that spermidine, cadaverine, and sym-nor-spermidine are the major components, with small amounts of sym-nor-spermine and N-(3-aminopropyl)cadaverine (APC). This is the first report in Archaea of an unusual polyamine APC that is proposed to play a role in stress adaptation.

Polyamine contents in current foods: a basis for polyamine reduced diet and a study of its long term observance and tolerance in prostate carcinoma patients

Polyamine contents were assessed by mass spectrometry in 233 current foods and beverages. In order to reduce gut polyamine uptake, a polyamine reduced diet (PRD) and partial intermittent intestinal tract decontamination (PIITD) with neomycin or nifuroxazide was proposed as nutritional therapy to 33 prostate carcinoma patients, 30 of whom with hormone refractory prostate cancer (HRPC). Mean PRD observance was 22 +/- 19 (median: 16; range: 3-72) months. 10, 8 and 3 patients were respectively on PRD for more than 30, 36 and 64 months. No diet toxicity was observed. 8 patients had moderate intestinal intolerance due to PIITD which was interrupted. No significant differences in body weight, blood counts or serum protein levels were observed during the follow-up of patients under PRD. Performance status and pain scores were relatively stable during the trial with improved pain scores at 6 months. A PRD associated with intermittent PIITD is a safe and well observed nutritional regimen and long term observance is possible.

Pleiotropic role of quorum-sensing autoinducer 2 in Photorhabdus luminescens

Bacterial virulence is an integrative process that may involve quorum sensing. In this work, we compared by global expression profiling the wild-type entomopathogenic Photorhabdus luminescens subsp. laumondii TT01 to a luxS-deficient mutant unable to synthesize the type 2 quorum-sensing inducer AI-2. AI-2 was shown to regulate more than 300 targets involved in most compartments and metabolic pathways of the cell. AI-2 is located high in the hierarchy, as it controls the expression of several transcriptional regulators. The regulatory effect of AI-2 appeared to be dose dependent. The luxS-deficient strain exhibited decreased biofilm formation and increased type IV/V pilus-dependent twitching motility. AI-2 activated its own synthesis and transport. It also modulated bioluminescence by regulating the synthesis of spermidine. AI-2 was further shown to increase oxidative stress resistance, which is necessary to overcome part of the innate immune response of the host insect involving reactive oxygen species. Finally, we showed that the luxS-deficient strain had attenuated virulence against the lepidopteran Spodoptera littoralis. We concluded that AI-2 is involved mainly in early steps of insect invasion in P. luminescens.

Simultaneous liquid chromatography determination of polyamines and arylalkyl monoamines

The diamines putrescine (PUT) and diaminopropane (DAP), the polyamines spermidine (SPD) and spermine (SPM), and the arylalkyl amines phenethylamine (PEA), tyramine (TYR), dopamine (DA), and salsolinol (SAL) were dansylated and baseline separated by LC using a Waters ODS-2 column. The dansyl derivatives were detected by fluorescence (lambda(ex): 337 nm; lambda(em): 520 nm). Besides the amine function, the phenolic OH groups of TYR, DA, and SAL were also dansylated (LC-MS, formation of N,O-didansyl [TYR] and N,O,O'-tridansyl derivatives [DA and SAL]). Calibration curves revealed response factors being appreciably lower for (N,O-didansyl) aminophenol TYR and (N,O,O'-tridansyl) DA and SAL than for N-dansylamines. However, the method is suitable as a cheap alternative to LC-MS for the simultaneous determination of polyamines and arylalkyl amines of large quantities of samples.

The new orally active iron chelator ICL670A exhibits a higher antiproliferative effect in human hepatocyte cultures than O-trensox

By comparing the antiproliferative effect of the iron chelators ICL670A and O-trensox in the human hepatoma cell line HUH7 and human hepatocyte cultures, we have shown that ICL670A decreased cell viability, inhibited DNA replication and induced DNA fragmentation more efficiently than O-trensox. O-trensox and ICL670A induced a cell cycle blockade in G0-G1 and S phases respectively. In parallel, ICL670A inhibited polyamine biosynthesis by decreasing ornithine decarboxylase and spermidine/spermine N(1)-acetyltransferase activities. O-trensox increased polyamine biosynthesis and particularly putrescine level by stimulating spermidine-spermine N(1)-acetyltransferase activity which could activate the polyamine retro-conversion pathway. Moreover, the two chelators exhibit some cytotoxic effect in the two culture models; ICL670A was more cytotoxic than O-trensox and higher concentrations of the two chelators were necessary to induce a cytotoxicity in primary cultures versus hepatoma cells. These results suggested that ICL670A has the most efficient antitumoral effect, blocks cell proliferation by a pathway different of O-trensox and may constitute a potential drug for anticancer therapy.

Regulation of arginase II by interferon regulatory factor 3 and the involvement of polyamines in the antiviral response

The innate antiviral response requires the induction of genes and proteins with activities that limit virus replication. Among these, the well-characterized interferon beta (IFNB) gene is regulated through the cooperation of AP-1, NF-kappaB and interferon regulatory factor 3 (IRF-3) transcription factors. Using a constitutively active form of IRF-3, IRF-3 5D, we showed previously that IRF-3 also regulates an IFN-independent antiviral response through the direct induction of IFN-stimulated genes. In this study, we report that the arginase II gene (ArgII) as well as ArgII protein concentrations and enzymatic activity are induced in IRF-3 5D-expressing and Sendai virus-infected Jurkat cells in an IFN-independent manner. ArgII is a critical enzyme in the polyamine-biosynthetic pathway. Of the natural polyamines, spermine possesses antiviral activity and mediates apoptosis at physiological concentrations. Measurement of intracellular polyamine content revealed that expression of IRF-3 5D induces polyamine production, but that Sendai virus and vesicular stomatitis virus infections do not. These results show for the first time that the ArgII gene is an early IRF-3-regulated gene, which participates in the IFN-independent antiviral response through polyamine production and induction of apoptosis.

Polyamines as clinical laboratory tools

Since their discovery by Antoni van Leeuwenhoek in 1678 until the recent development of transgenic mice expressing proteins altering polyamine levels in a tissue-specific manner, polyamines have been the object of intense research efforts which have shed light on several biological and pathological processes. From the discovery of a particular form of proteasome regulation of the catabolism of the key regulatory enzyme in their synthetic pathway, to the experimental cancer treatment or prevention with polyamine antagonists or inhibitors of the latter enzyme, a whole spectrum of interests can be revealed. Still, many aspects of their functions remain elusive and difficulties inherent in their analysis, which relies on sophisticated high-performance liquid chromatographic (HPLC) methods, and the lack of standardization; have hampered the transit from the research realm to the standard clinical laboratory domain. Their assay in biological fluids has been used for cancer diagnosis and for monitoring anticancer treatment. In this article, we attempt to provide an overview of polyamine structure, nutritional value, metabolism, and physiological roles. Next, we will summarize the main analytical methods on which we count, and finally we will address their role in diagnosis of cancer as well their proposed role as antioxidant and antiglycation agents.

Defining the Molecular Requirements for the Selective Delivery of Polyamine Conjugates into Cells Containing Active Polyamine Transporters

Several N(1)-substituted polyamines containing various spacer units between nitrogen centers were synthesized as their respective HCl salts. The N(1)-substituents included benzyl, naphthalen-1-ylmethyl, anthracen-9-ylmethyl, and pyren-1-ylmethyl. The polyamine spacer units ranged from generic (4,4-triamine, 4,3-triamine, and diaminooctane) spacers to more exotic [2-(ethoxy)ethanoxy-containing diamine, hydroxylated 4,3-triamine, and cyclohexylene-containing triamine] spacers. Two control compounds were also evaluated: N-(anthracen-9-ylmethyl)-butylamine and N-(anthracen-9-ylmethyl)-butanediamine. Biological activities in L1210 (murine leukemia), alpha-difluoromethylornithine (DFMO)-treated L1210, and Chinese hamster ovary (CHO) and its polyamine transport-deficient mutant (CHO-MG) cell lines were investigated via IC(50) cytotoxicity determinations. K(i) values for spermidine uptake were also determined in L1210 cells. Of the series studied, the N(1)-benzyl-4,4-triamine system 6 had significantly higher IC(50) values (lower cytotoxicity) in the L1210, CHO, and CHO-MG cell lines. A cellular debenzylation process was observed in L1210 cells with 6 and generated "free" homospermidine. The size of the N(1)-arylmethyl substituent had direct bearing on the observed cytotoxicity in CHO-MG cells. The N(1)-naphthalenylmethyl, N(1)-anthracenylmethyl, and N(1)-pyrenylmethyl 4,4-triamines had similar toxicity (IC(50)s: approximately 0.5 microM) in CHO cells, which have an active polyamine transporter (PAT). However, this series had IC(50) values of >100 microM, 66.7 microM, and 15.5 microM, respectively, in CHO-MG cells, which are PAT-deficient. The observed lower cytotoxicity in the PAT-deficient CHO-MG cell line supported the premise that the conjugates use PAT for cellular entry. In general, moderate affinities for the polyamine transporter were observed for the N-arylmethyl 4,4-triamine series with their L1210 K(i) values all near 3 microM. In summary, the 4,4-triamine motif was shown to facilitate entry of polyamine conjugates into cells containing active polyamine transporters.