Management of augmentation of restless legs syndrome with rotigotine: a 1-year observational study.

AIM: The aim of this study is to assess the effect of switching to rotigotine transdermal patch on severity of restless legs syndrome (RLS) in patients who experienced acute augmentation with previous oral dopaminergics. METHODS: In this 13-month observational study, adults with moderate-to-severe RLS and augmentation were switched to rotigotine per the physician's independent decision. Assessments included Clinical Global Impression severity score (CGI-1); (primary), treatment regimen for switching (secondary), RLS-6, International RLS Study Group Rating Scale (IRLS), and augmentation severity rating scale (ASRS). RESULTS: A total of 99 patients received rotigotine, of whom 46 completed observational period, and 43 were assessed for effectiveness. A total of 5 patients switched to rotigotine after a >1-day drug holiday, 23 switched overnight, 9 had an overlapping switch, and 6 received ongoing oral dopaminergics with rotigotine for ≥28 days. Of the 99 patients, 57 took concomitant RLS medications (excluding switching medications) on at least 1 day. At the final visit, median change in CGI-1 (Hodges-Lehman estimate [95% CI]) was -2.0 (-2.5, -1.50); 37 of the 43 patients improved by ≥1 CGI-1 category, and 16 of 43 were responders (≥50% improvement). RLS-6 and IRLS scores also improved. Patients had median ASRS of 0 at the final visit indicating "no worsening/occurrence of augmentation." ASRS item 1 showed a shift in mean time of symptom onset (24-h clock) from 12:38 (baseline) to 18:25 (final visit). Most common reasons for withdrawal of rotigotine were adverse events (26 patients) and lack of efficacy (14 patients). CONCLUSIONS: Switching from oral therapies to rotigotine was effective in improving RLS symptoms in 37 of the 43 patients (from the original population of 99 patients) who remained in the study over 13 months. CLINICAL TRIAL REGISTRATION: ClinicalTrials.govNCT01386944.

Caregivers' and physicians' attitudes to rotigotine transdermal patch versus oral Parkinson's disease medication: an observational study.

OBJECTIVE: To provide real-world data on caregiver and physician perceptions of the advantages and disadvantages of rotigotine transdermal patch (Neupro * ) versus oral Parkinson's Disease (PD) medication. METHODS: Cross-sectional, non-interventional study in routine clinical practice in Germany (NCT01330290). Patients had PD with documented need for care, and had received rotigotine transdermal patch as add-on to oral PD treatment for ≥1 month. Caregivers/nurses and physicians assessed rotigotine transdermal patch versus oral PD medications using questionnaires. Specific questions regarding the possible benefits of transdermal application were asked and comprised questions on: swallowing dysfunction, nausea/vomiting, monitoring therapy, once daily application, application independently from meals, application to sleeping patients, caregiving efforts (caregivers only) and clinical aspects (physicians only). Each question was assessed on a 5 point scale ranging from -2 (major disadvantage) to 2 (major advantage) compared with oral treatment. Primary outcomes were mean total scores of all questions for caregivers/nurses and physicians who provided responses for ≥4 questions. As there are no validated tools to assess physician/caregiver preference in the PD setting, there is no reference against which the current findings can be compared; this study serves to pilot the questionnaires. RESULTS: Questionnaire responses from 128 caregivers/nurses and 41 physicians were documented for 147 patients. One hundred (68%) patients had a caregiving family member; 40 (27%) were cared for by a nurse. Mean PD duration was 8.2 (SD 6.3) years; 136 (93%) patients were taking levodopa. Mean total score of caregivers'/nurses' questionnaires was 1.32 (SD 0.67) and of physicians' questionnaires was 1.46 (0.32) indicating a perceived advantage of rotigotine transdermal patch over oral PD therapy. Mean scores for individual questions were in the range 1.03-1.54 for caregivers/nurses and 1.15-1.87 for physicians. When given a choice about rationale to prescribe, physicians cited pharmaceutical form (patch) in 139 (95%) cases and active agent (rotigotine) in 89 (61%) cases. CONCLUSION: Caregivers/nurses and physicians perceived advantages with rotigotine transdermal patch compared to an oral PD medication as add-on therapy in patients with PD; advantages were observed in aspects of medical treatment as well as in everyday situations of caregiving of PD patients.

Reduction of gastrointestinal symptoms in Parkinson's disease after a switch from oral therapy to rotigotine transdermal patch: a non-interventional prospective multicenter trial.

INTRODUCTION: Gastrointestinal (GI) symptoms are common among patients with Parkinson's disease (PD), due to both the disease itself and anti-PD drugs. We hypothesized that transdermal drug administration may result in fewer GI problems. This prospective observational study (ClinicalTrials.gov: NCT01159691) investigated effect of switching to rotigotine transdermal patch from oral anti-PD medications in patients with PD and existing GI symptoms. METHODS: Patients were enrolled if their physician was planning to switch them to rotigotine because of GI symptoms experienced while receiving oral anti-PD medications. Effectiveness assessments included a visual analog scale (VAS) measuring intensity of GI symptoms from 0 (no disorder) to 100 mm (extremely severe disorder), a questionnaire on the frequency and intensity of six individual GI complaints (heartburn, bloating, nausea, vomiting, abdominal pain, diarrhea), each rated 0-12 for a sum score of 0-72, and patient satisfaction regarding GI symptoms over approximately 6 weeks after switching. RESULTS: Of 75 patients who received rotigotine, 58 had follow-up data available for final analysis. Intensity of GI complaints improved numerically on both the VAS (47.5 ± 24.4 mm [n = 65] at baseline, 19.7 ± 23.3 mm [n = 58] after around 6 weeks) and the sum score of GI complaints (11.2 ± 9.0 at baseline, 2.1 ± 4.4 [n = 58] after around 6 weeks). Fifty of 58 patients were "satisfied" or "very satisfied" regarding GI symptoms over around 6 weeks following switch to the patch. CONCLUSION: This study suggests that a switch from oral anti-PD medications to rotigotine transdermal patch may improve existing GI symptoms among patients with PD. Additional controlled studies are needed to confirm this finding.

New serotonin 5-HT1A receptor agonists endowed with antinociceptive activity in vivo.

We report the synthesis of new compounds 4-35 based on two different openings (A and B) of the chromane ring present in the previously identified 5-HT1A receptor (5-HT1AR) ligand 3. The synthesized compounds were assessed for binding affinity, selectivity, and functional activity at the 5-HT1AR. Selected candidates resulting from B opening were also evaluated for their potential antinociceptive effect in vivo and pharmacokinetic properties in vitro. Analogue 19 [2-(4-{[2-(2-ethoxyphenoxy)ethyl]amino}butyl)tetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione] has been characterized as a high-affinity and potent 5-HT1AR agonist (Ki = 2.3 nM; EC50 = 19 nM). Pharmacokinetic studies indicated that compound 19 displays a good metabolic stability in human liver microsomes (t1/2 ∼ 3 h and CLint = 3.5 mL/min/kg, at 5 µM), and a low level of protein binding (25%, at 5 µM). Interestingly, 19 (3 mg/kg, ip, and 30 mg/kg, po) caused significant attenuation of formalin-induced behavior in early and late phases of the mouse intradermal formalin test of pain, and this in vivo effect was reversed by the selective 5-HT1AR antagonist WAY-100635. Thus, the new 5-HT1AR agonist identified in this work, 19, exhibits oral analgesic activity, and the results herein represent a step toward identifying new therapeutics for the control of pain.

Effectiveness and tolerability of rotigotine transdermal patch for the treatment of restless legs syndrome in a routine clinical practice setting in Germany.

OBJECTIVE: We aimed to assess effectiveness and tolerability of rotigotine in patients with moderate to severe idiopathic restless legs syndrome (RLS) under daily practice conditions in Germany. METHODS: In this 3-month noninterventional study, effectiveness was assessed using RLS-6 (primary variables were symptom severity when falling asleep [item 2] and during the night [item 3]). Data were collected at baseline and at the end of treatment. Safety assessments included adverse events (AEs). RESULTS: Six hundred and eighty-four patients were treated with rotigotine and 418 (61%) completed the study. The full analysis set (FAS) comprised 564 patients (106 de novo; 458 pretreated [454 had complete rotigotine dosing data]). Mean rotigotine dose of longest duration was 2.4±1.4 mg/24 h. Rotigotine improved all RLS-6 items (mean change from baseline [item 2], -2.4±3.6; [item 3], -2.7±3.4), with the most pronounced improvement observed in daytime symptoms while at rest (item 4, -2.9±3.2). AEs were typical of dopaminergic treatment and transdermal administration. De novo patients generally started rotigotine on 1 mg/24 h (85% [90/106]) and pretreated patients on 1 (50% [227/454]) or 2 mg/24 h (40% [183/454]). Most patients who were pretreated with levodopa (57%), pramipexole (84%), or ropinirole (78%) monotherapy discontinued these medications on initiation of rotigotine. CONCLUSIONS: Rotigotine was effective and well-tolerated when used in routine clinical practice.

Preconditioning by toll-like receptor 2 agonist Pam3CSK4 reduces CXCL1-dependent leukocyte recruitment in murine myocardial ischemia/reperfusion injury.

OBJECTIVE: To test whether preconditioning with a toll-like receptor (TLR) 2 agonist protects against myocardial ischemia and reperfusion by interfering with chemokine CXCL1 release from cardiomyocytes. DESIGN: C3H mice were challenged with vehicle or synthetic TLR2 agonist Pam3Cys-Ser-Lys4 (Pam3CSK4; 1 mg/kg) 24 hrs before myocardial ischemia (20 mins) and reperfusion (2 hrs or 24 hrs). Infarct size, troponin T release, and leukocyte recruitment were quantified. In murine cardiomyocytes (HL-1), we studied the expression/activation profile of TLR2 in response to stimulation with Pam3CSK4 (0.01-1 mg/mL). Furthermore, we studied the chemokine ligand 1 (CXCL1) response to Pam3CSK4 and ischemia/reperfusion in vivo and in vitro. SETTING: University hospital research laboratory. SUBJECTS: Anesthetized male mice and murine cardiomyocytes. MEASUREMENTS AND MAIN RESULTS: Preconditioning by Pam3CSK4 reduced infarct size and troponin T release. This was accompanied by a decreased recruitment of leukocytes into the ischemic area and an improved cardiac function. In HL-1 cells, TLR2 activation amplified the expression of the receptor in a time-dependent manner and led to CXCL1 release in a concentration-dependent manner. Preconditioning by Pam3CSK4 impaired CXCL1 release in response to a second inflammatory stimulus in vivo and in vitro. CONCLUSIONS: Preconditioning by TLR2 agonist Pam3CSK4 reduces myocardial infarct size after myocardial ischemia/reperfusion. One of the mechanisms involved is a diminished chemokine release from cardiomyocytes, which subsequently limits leukocyte infiltration.

The in vitro receptor profile of rotigotine: a new agent for the treatment of Parkinson's disease.

Rotigotine (Neupro) is a non-ergoline dopamine agonist developed for the once daily treatment of Parkinson's disease (PD) using a transdermal delivery system (patch) which provides patients with the drug continuously over 24 h. To fully understand the pharmacological actions of rotigotine, the present study determined its extended receptor profile. In standard binding assays, rotigotine demonstrated the highest affinity for dopamine receptors, particularly the dopamine D3 receptor (Ki=0.71 nM) with its affinities to other dopamine receptors being (Ki in nM): D4.2 (3.9), D4.7 (5.9), D5 (5.4), D2 (13.5), D4.4 (15), and D1 (83). Significant affinities were also demonstrated at alpha-adrenergic (alpha2B, Ki=27 nM) and serotonin receptors (5-HT1A Ki=30 nM). In newly developed reporter-gene assays for determination of functional activity, rotigotine behaved as a full agonist at dopamine receptors (rank order: D3>D2L>D1=D5>D4.4) with potencies 2,600 and 53 times higher than dopamine at dopamine D3 and D2L receptors, respectively. At alpha-adrenergic sites, rotigotine acted as an antagonist on alpha2B receptors. At serotonergic sites, rotigotine had a weak but significant agonistic activity at 5-HT1A receptors and a minor or nonexistent activity at other serotonin receptors. Thus, in respect to PD, rotigotine can be characterized as a specific dopamine receptor agonist with a preference for the D3 receptor over D2 and D1 receptors. In addition, it exhibits interaction with D4 and D5 receptors, the role of which in relation to PD is not clear yet. Among non-dopaminergic sites, rotigotine shows relevant affinity to only 5-HT1A and alpha2B receptors. Further studies are necessary to investigate the contribution of the different receptor subtypes to the efficacy of rotigotine in Parkinson's disease and possible other indications such as restless legs syndrome.

Inducible nitric oxide synthase and heme oxygenase-1 in the lung during lipopolysaccharide tolerance and cross tolerance.

OBJECTIVE: Pretreatment with low-dose lipopolysaccharide protects cells/organs against a subsequent lethal Gram-negative (lipopolysaccharide tolerance) or Gram-positive (cross tolerance) stimulus. We determined whether this occurs in the rat lung. The involvement of inducible nitric oxide synthase and heme oxygenase-1 was evaluated. DESIGN: Laboratory study. SETTING: University hospital laboratory. SUBJECTS: Anesthetized male Wistar rats. INTERVENTIONS: To test the hypothesis, rats received saline or lipopolysaccharide (1 mg/kg). At 2, 4, 8, 16, or 24 hrs later, blood samples and lung tissue were taken to determine messenger RNA, protein concentration, and activity of inducible nitric oxide synthase and heme oxygenase-1. In additional experiments, rats were challenged with lipopolysaccharide (1 mg/kg) and subjected to Gram-negative (lipopolysaccharide) or Gram-positive (lipoteichoic acid and peptidoglycan) shock 24 hrs later. These studies were carried out in the presence and absence of inducible nitric oxide synthase or heme oxygenase-1 inhibitors (1400W or tin protoporphyrin IX). Following 6 hrs of shock, lung tissue was taken to determine lung damage and heme oxygenase-1 concentration and activity. MEASUREMENTS AND MAIN RESULTS: In the rat lung, lipopolysaccharide (1 mg/kg) induced a significant increase in inducible nitric oxide synthase protein at 8 hrs with a corresponding increase in plasma nitrate/nitrite at 8-16 hrs. Simultaneously, heme oxygenase-1 messenger RNA transcripts were observed at 8-16 hrs, and maximal expression of the protein followed (24 hrs). Pretreatment with low-dose lipopolysaccharide reduced myeloperoxidase activity (neutrophil infiltration) and wet-dry ratio (pulmonary edema) in the lungs of animals subjected to Gram-negative or Gram-positive shock, demonstrating tolerance. Pretreatment with low-dose lipopolysaccharide and the selective inducible nitric oxide synthase inhibitor 1400W reduced heme oxygenase-1 protein expression, and lung protection was abolished. Tin protoporphyrin IX did not affect heme oxygenase-1 expression, but heme oxygenase activity and lung protection were significantly reduced. CONCLUSIONS: We propose that nitric oxide (most likely inducible nitric oxide synthase derived) regulates the induction of heme oxygenase-1 in the lung, which in turn plays an important part in pulmonary protection during lipopolysaccharide tolerance and cross tolerance.

Toll-like receptor 9 expression in murine and human adrenal glands and possible implications during inflammation.

CONTEXT: Sepsis is a leading cause of death in the Western world and can be associated with failure of the hypothalamic-pituitary-adrenal axis. A coordinated response of the adrenal and immune system is of vital importance for survival during sepsis. Within the immune response, Toll-like receptors (TLRs) play a crucial role by recognizing pathogen-associated molecules such as bacterial DNA. TLR-9 can detect motifs of unmethylated cytosine-phosphate-guanine (CpG) dinucleotides (CpG-DNA) being present in bacterial DNA. OBJECTIVE: We investigated whether TLR-9 is expressed in human and murine adrenal glands and whether its activation is associated with an adrenal response. DESIGN: Human fetal and adult adrenal glands; wild-type, C57BL/6 and TLR-9 deficient (TLR-9-/-) mice; and in vitro cell line models were used in the study. SETTING: The study took place at a university hospital. RESULTS: TLR-9 is expressed in human and murine adrenal glands, as well as in in vitro cell lines (Y-1 and NCI-H295R cells). CpG-oligodeoxynucleotide challenge caused a 3-fold increase in plasma levels of corticosterone in wild-type mice. This effect was not observed in TLR-9-/- mice. Furthermore, CpG-oligodeoxynucleotide challenge resulted in a strong release of several inflammatory cytokines, such as TNF-alpha, and IL-1beta, -6, -10, and -12 in vivo as well as in vitro. Again, this effect was not present in TLR-9-/- mice. CONCLUSIONS: TLR-9 is present in both murine and human adrenal glands. TLR-9 stimulation led to a corticosterone and inflammatory cytokine response. TLR-9 may play a role in the regulation of the hypothalamic-pituitary-adrenal axis during conditions in which bacterial DNA is present.

Toll-like receptor 4 plays a crucial role in the immune-adrenal response to systemic inflammatory response syndrome.

Sepsis and septic shock are leading killers in the noncoronary intensive care unit, and they remain worldwide health concerns. The initial host defense against bacterial infections involves Toll-like receptors (TLRs), which detect and respond to microbial ligands. In addition, a coordinated response of the adrenal and immune systems is crucial for survival during severe inflammation. Previously, we demonstrated a link between the innate immune system and the endocrine stress response involving TLR-2. Like TLR-2, TLR-4 is also expressed in human and mouse adrenals. In the present work, by using a low dose of LPS to mimic systemic inflammatory response syndrome, we have revealed marked cellular alterations in adrenocortical tissue and an impaired adrenal corticosterone response in TLR-4-/- mice. Our findings demonstrate that TLR-4 is a key mediator in the crosstalks between the innate immune system and the endocrine stress response. Furthermore, TLR polymorphisms could contribute to the underlying mechanisms of impaired adrenal stress response in patients with bacterial sepsis.

Endothelial antioxidant actions of dihydropyridines and angiotensin converting enzyme inhibitors.

Dihydropyridines and angiotensin converting enzyme inhibitor effects on superoxide and nitric oxide (NO) were compared in high glucose (20 mM, 24 h)-treated human Ea.hy 926 endothelial cells. High glucose stimulated superoxide both extracellularly (lucigenin chemiluminescence, cytochrome c reduction) and intracellularly (dihydrorhodamine 123 fluorescence). The dihydropyridines amlodipine, nisoldipine, BayK 8644 or the angiotensin converting enzyme inhibitors captopril and enalaprilat attenuated extra- and intracellular superoxide formation; nifedipine blocked extracellular increases only, ramiprilat was without antioxidant effect. Dihydropyridines and captopril also prevented NADPH-driven superoxide release. Antioxidant actions were blunted by a bradykinin B(2) receptor antagonist or an inhibitor of p38 mitogen activated protein kinase (MAPK), and were accompanied by improved NO release (amperometric sensor). p38MAPK inhibition prevented the NO-sparing actions of dihydropyridines but not angiotensin converting enzyme inhibitors. Thus, dihydropyridines and angiotensin converting enzyme inhibitors limit high glucose-induced superoxide formation and improve NO bioavailability in human endothelial cells, in part via bradykinin and p38MAPK.

Antioxidant and nitric oxide-sparing actions of dihydropyridines and ACE inhibitors differ in human endothelial cells.

The effects of dihydropyridine Ca2+ channel blockers (DHP) and ACE inhibitors on superoxide formation and nitric oxide (NO) bioavailability were compared in human EA.Hy926 endothelial cells (EC). EC were stimulated 4 h with angiotensin II (Ang II, 10 nM) +/- study drugs. Specific superoxide formation was measured by lucigenin-enhanced chemiluminescence, reduction of cytochrome c and rhodamine-123 fluorescence. Free NO release was determined with an amperometric NO sensor. NADPH oxidase subunits expression was examined with Western Blot. In untreated EC the intracellular superoxide is -64.3 +/- 6.0% decreased compared to Ang II stimulated EC. Elevated extracellular superoxide formation was on a -43.0 +/- 1.7% lower level in untreated EC. The DHP Ca2+-channel agonist BayK8644 and ACE inhibitors captopril and ramiprilat led extracellular superoxide concentration to control level. Enalaprilat blocked extracellular superoxide, the DHP amlodipine and nisoldipine prevented intracellular increases only (n = 8-9, p < 0.05). Icatibant (HOE 140), a kinin-B2 receptor antagonist, attenuated antioxidant actions of all tested agents except of nisoldipine. Ang II-induced superoxide was elevated by the phorbolester PMA and blocked by the protein kinase C (PKC) inhibitor chelerythrine. Suppression of substance P-evoked NO release by Ang II (>70%, n = 6) was reversed by the PKC inhibitor chelerythrine, the DHP amlodipine and nisoldipine and the ACE inhibitor ramiprilat. Further, Ang II reduces Nox-4 expression by 34.5 +/- 4.9. Nox-2 expression was not regulated. DHP and ACE inhibitors exert different antioxidant effects in human EC stimulated with Ang II, but both improve NO bioavailability via bradykinin and modulation of redox-regulating enzymes.

Different antioxidative potencies of dihydropyridine calcium channel modulators in various models.

There is evidence that dihydropyridine calcium antagonists (DHP) play a beneficial role during the development of atherosclerosis. Since antioxidative properties of this substance class may be important, we investigated the antioxidative potency of the DHP prototype calcium channel antagonist nifedipine, the long acting calcium channel antagonist lacidipine, the DHP calcium channel agonist Bay K 8644 and the bulky DHP derivate Bay O 5572 (negligible effects on L-type calcium channels) in three different models. Additionally, we examined the potential correlation between lipophilic and antioxidative properties. In an in vitro model, Bay K 8644 was significantly more effective in scavenging superoxide anions (hypoxanthine/xanthine-oxidase-assay) than lacidipine, Bay O 5572 or nifedipine (micro- to millimolar concentration range). Addition of artificial membrane preparations (dimyristoylphosphatidylcholine) to mimic a physiological environment resulted in an enhanced antioxidative effect, with lacidipine being the most effective DHP to quench radicals (low micromolar concentration range). Thirdly, in a more physiological model of hyperglycemia (30 mmol/l) induced release of reactive oxygen species (ROS) from native endothelial cells of porcine coronary arteries, we showed that nifedipine was a significantly more potent antioxidant (therapeutical nanomolar concentration range) than the other DHP. Calculation of the lipophilicity of the four substances (lacidipine>Bay O 5572>Bay K 8644>nifedipine) showed a positive correlation between the antioxidative potency and the lipophilicity in the model with the artificial membranes but not in the other models. We conclude that it seems necessary to access antioxidative properties of substances in physiological models in which we could demonstrate that nifedipine exhibits ROS-quenching properties in a therapeutic concentration range.

Discovery of the ergothioneine transporter.

Variants of the SLC22A4 gene are associated with susceptibility to rheumatoid arthritis and Crohn's disease. SLC22A4 codes for an integral membrane protein, OCTN1, that has been presumed to carry organic cations like tetraethylammonium across the plasma membrane. Here, we show that the key substrate of this transporter is in fact ergothioneine (ET). Human OCTN1 was expressed in 293 cells. A substrate lead, stachydrine (alias proline betaine), was identified by liquid chromatography MS difference shading, a new substrate search strategy. Analysis of transport efficiency of stachydrine-related solutes, affinity, and Na+ dependence indicates that the physiological substrate is ET. Efficiency of transport of ET was as high as 195 microl per min per mg of protein. By contrast, the carnitine transporter OCTN2 from rat did not transport ET at all. Because ET is transported >100 times more efficiently than tetraethylammonium and carnitine, we propose the functional name ETT (ET transporter) instead of OCTN1. ET, all of which is absorbed from food, is an intracellular antioxidant with metal ion affinity. Its particular purpose is unresolved. Cells with expression of ETT accumulate ET to high levels and avidly retain it. By contrast, cells lacking ETT do not accumulate ET, because their plasma membrane is virtually impermeable for this compound. The real-time PCR expression profile of human ETT, with strong expression in CD71+ cells, is consistent with a pivotal function of ET in erythrocytes. Moreover, prominent expression of ETT in monocytes and SLC22A4 polymorphism associations suggest a protective role of ET in chronic inflammatory disorders.

Measurement of nitric oxide by reconversion of nitrate/nitrite to NO.

A simple and sensitive method is presented to measure the unstable molecule nitric oxide (NO) by reconversion of nitrate/nitrite to NO. Nitrate and nitrite are the stable degradation products of NO that accumulate in supernatants of biological samples that release nitric oxide. First, nitrate is enzymatically converted to nitrite using nitrate reductase. In a second step, nitrite is reduced to equimolar NO concentrations by an acidic iodide solution and quantified with an amperometric Clark-type electrode. This method provides the ability to assess basal-and agonist-stimulated cumulative NO formation in different biological models and is a sensitive alternative to the widely used Griess assay.

Influence of processing parameters on acrylamide formation during frying of potatoes.

Consistent evidence suggests that the probable human carcinogen acrylamide is formed in starch-rich foodstuffs through heat-induced interaction of asparagine and reducing sugars during Maillard browning. However, information regarding the influence of processing parameters on acrylamide formation is scarce. We investigated the impact of temperature, heating time, browning level, and surface-to-volume ratio (SVR) on acrylamide generation in fried potatoes. Acrylamide content was determined by liquid chromatography (LC) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). In potato shapes with low SVR, acrylamide content consistently increased with increasing temperature and processing times. By contrast, in shapes with intermediate to high SVR, maximal acrylamide formation occurred at 160-180 degrees C, while higher temperatures or prolonged processing times caused a decrease of acrylamide levels. Moreover, browning levels were not a reliable measure of acrylamide content in large-surface products.

Agmatine signaling: odds and threads.

Agmatine is a metabolite of L-arginine. It is formed by the decarboxylation of L-arginine via arginine decarboxylase in bacteria, plants and mammals. It is becoming clear that it has multiple physiological functions as a potential transmitter. Agmatine binds to alpha2-adrenoceptors and to imidazoline binding sites. It blocks NMDA receptors and other ligand-gated cation channels. It also inhibits nitric oxide synthase, induces release of peptide hormones and antizyme and plays a role during cell proliferation by interacting with the generation and transport of polyamines. Although the precise function of endogenously released agmatine is presently still unclear, this review will summarize several aspects concerning the biological function of agmatine.

The localisation of the extraneuronal monoamine transporter (EMT) in rat brain.

The extraneuronal monoamine transporter plays an important role in the inactivation of monoamine transmitters. A basal extraneuronal tissue expression of this transporter has been reported, but it is also expressed in CNS glia. As little is known about the expression pattern and the function of the extraneuronal monoamine transporter in the brain, we performed a detailed investigation. Firstly, a northern blot analysis of different rat organs revealed that the transporter is strongly expressed in placenta, lung and heart and less prominently in the whole brain, brain stem, intestine, testis, epididymis, stomach, kidney and skeletal muscle. It was not expressed in cerebellum, liver and embryo. Using an in situ hybridization to the rat brain, we detected a marked and highly confined expression of the extraneuronal monoamine transporter in the area postrema, but in no other brain areas. These findings were confirmed by polyclonal antibodies against rat extraneuronal monoamine transporter showing an intensive signal in the area postrema, although a few cells in the cerebellum and the brain stem also showed a signal. Additionally, a partly overlapping expression pattern of the monoamine oxidase-B was detected. Summarizing, we firstly describe a marked and highly confined expression of the extraneuronal monoamine transporter in the rat area postrema by in situ hybridisation which may play a role in physiological functions of this circumventricular organ such as emesis, food intake and the regulation of cardiovascular functions.

Amlodipine increases endothelial nitric oxide by dual mechanisms.

Several experimental and clinical studies have demonstrated the antiatherogenic profile of the long-acting calcium antagonist amlodipine. Given the pivotal role of endothelial (dys)function during atherogenesis, we investigated the influence of amlodipine on endothelial nitric oxide (NO) bioavailability. Acute addition of amlodipine to segments of porcine coronary arteries resulted in a significant increase in NO release which could be blocked by the NO synthase inhibitor L-NMMA (N-monomethylarginine). This effect was mirrored by a rise in intracellular cGMP levels in porcine endothelial cell cultures. Long-term (24 h) treatment of porcine endothelial cell cultures with amlodipine (0.1-10 micromol/l) significantly enhanced the basal NO formation in a concentration-dependent manner which was abrogated in the presence of L-NMMA (0.1 mmol/l). In EA.hy 926 endothelial cells, amlodipine treatment for 24 h significantly increased the endothelial NO synthase protein expression. To evaluate whether the observed increase in NO was additionally due to an antioxidative protection of NO, we examined the influence of amlodipine in different in vitro models. In a cell-free system, amlodipine quenched superoxide anions (hypoxanthine/xanthine oxidase assay) at high concentrations (150 micromol/l). Addition of artificial membrane preparations (dimyristoylphosphatidylcholine) to mimic a physiological environment significantly enhanced this antioxidative effect. In a more physiological model of hyperglycemia (30 mmol/l, 20 min) induced formation of reactive oxygen species from native endothelial cells of porcine coronary arteries, amlodipine concentration dependently attenuated the reactive oxygen species release (>60%; 10 micromol/l). We conclude, that amlodipine increases the endothelial NO bioavailability, firstly via enhanced NO formation and secondly by prolonging the half-life of NO through antioxidative properties. This may result in an improved endothelial function.

Reaction rate constants of superoxide scavenging by plant antioxidants.

Plant phenols may exert protective effects by scavenging superoxide, which is implicated in tissue damage and accelerated inactivation of vasorelaxing nitric oxide. Preventing the interaction of superoxide with tissue biomolecules depends not only on the extent of superoxide scavenging but also on scavenging velocity. However, information on superoxide scavenging kinetics of plant phenols is scarce. We describe an improved lucigenin-based chemiluminescence assay for kinetic analysis. The use of potassium superoxide (KO2) as a nonenzymatic superoxide source allowed simple and reliable determination of the second-order reaction rate constants between superoxide and plant antioxidants at physiologically relevant conditions, avoiding unspecific effects of other reactive oxygen species or superoxide-generating enzymes. We calculated the rate constants for phenols of different structures, ranging from 2.9 x 10(3) mol(-1) l s(-1) for morin to 2.9 x 10(7) mol(-1) l s(-1) for proanthocyanidins. Compounds with pyrogallol or catechol moieties were revealed as the most rapid superoxide scavengers, and the gallate moiety was found to be the minimal essential structure for maximal reaction rate constants with superoxide.