Platelet, Plasma, Urinary Tryptophan-Serotonin-Kynurenine Axis Markers in Hyperacute Brain Ischemia Patients: A Prospective Study.

Background and Purpose: Ischemic stroke is one of the most common causes of morbidity and mortality and has numerous clinical mimics. Previous studies have suggested a potential role of the tryptophan-serotonin (5-HT)-kynurenine (TSK) axis in ischemic stroke. Studies assessing this axis in the hyperacute phase of ischemic stroke (<4.5 h) are lacking. This prospective study thus evaluates the TSK axis in transient ischemic attack (TIA) and hyperacute ischemic stroke (AIS) patients. Methods: This study included 28 patients (24 AIS and 4 TIA) and 29 controls. The blood and urine samples of patient were collected within 4.5 h of symptoms onset (day 0, D0), then at 24 h and 3 months. Control blood and urine samples were collected once (D0). The TSK axis markers measured were platelet serotonin transporter (SERT) and 5-HT2A receptor (5-HT2AR) densities and platelet, plasma, and urinary 5-HT, plasma and urinary 5-hydroxyindole acetic acid (5-HIAA), and plasma kynurenine and tryptophan (TRP) levels. Results: At D0, patients exhibited a lower (p = 10-5) platelet SERT density, higher (p < 10-6) platelet 5-HT2AR density, higher (p = 10-5) plasma kynurenine/tryptophan (K/T) ratio, and higher urinary 5-HT (p = 0.011) and 5-HIAA (p = 0.003) levels than controls. Conclusions: We observed, for the first time, a hyperacute dysregulation of the serotonergic axis, and hyperacute and long-lasting activation of the tryptophan-kynurenine pathway in brain ischemia.

Tryptophan pathway catabolites (serotonin, 5-hydroxyindolacetic acid, kynurenine) and enzymes (monoamine oxidase and indole amine 2,3 dioxygenase) in patients with septic shock: A prospective observational study versus healthy controls.

Septic shock is associated with a strong inflammatory response that induces vasodilation and vascular hyporeactivity. We investigated the role for tryptophan-pathway catabolites of proinflammatory cytokines in septic shock.We prospectively included 30 patients with very recent-onset septic shock and 30 healthy volunteers. The following were assayed once in the controls and on days 1, 2, 3, 7, and 14 in each patient: plasma free and total tryptophan, platelet and plasma serotonin, total blood serotonin, urinary serotonin, plasma and urinary 5-hydroxyindolacetic acid, plasma kynurenine, monoamine oxidase activity, and total indole amine 2,3-dioxygenase activity. Organ-system failure and mortality were recorded.Compared with the healthy controls, the patients with septic shock had 2-fold to 3-fold lower total tryptophan levels throughout the 14-day study period. Platelet serotonin was substantially lower, while monoamine oxidase activity and 5-hydroxyindolacetic acid were markedly higher in the patients than in the controls, consistent with the known conversion of tryptophan to serotonin, which is then promptly and largely degraded to 5-hydroxyindolacetic acid. Plasma kynurenine was moderately increased and indole amine 2,3-dioxygenase activity markedly increased in the patients versus the volunteers, reflecting conversion of tryptophan to kynurenine. Changes over time in tryptophan metabolites were not associated with survival in the patients but were associated with the Sequential Organ Failure Assessment score and hemodynamic variables including hypotension and norepinephrine requirements.Our results demonstrate major tryptophan pathway alterations in septic shock. Marked alterations were found compared with healthy volunteers, and tryptophan metabolite levels were associated with organ failure and hemodynamic alterations. Tryptophan metabolite levels were not associated with surviving septic shock, although this result might be ascribable to the small sample size.Trial registration: ClinicalTrials.gov; No: NCT00684736; URL: www.clinicaltrials.gov.

Alterations in the hypothalamic melanocortin pathway in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis, the most common adult-onset motor neuron disease, leads to death within 3 to 5 years after onset. Beyond progressive motor impairment, patients with amyotrophic lateral sclerosis suffer from major defects in energy metabolism, such as weight loss, which are well correlated with survival. Indeed, nutritional intervention targeting weight loss might improve survival of patients. However, the neural mechanisms underlying metabolic impairment in patients with amyotrophic lateral sclerosis remain elusive, in particular due to the lack of longitudinal studies. Here we took advantage of samples collected during the clinical trial of pioglitazone (GERP-ALS), and characterized longitudinally energy metabolism of patients with amyotrophic lateral sclerosis in response to pioglitazone, a drug with well-characterized metabolic effects. As expected, pioglitazone decreased glycaemia, decreased liver enzymes and increased circulating adiponectin in patients with amyotrophic lateral sclerosis, showing its efficacy in the periphery. However, pioglitazone did not increase body weight of patients with amyotrophic lateral sclerosis independently of bulbar involvement. As pioglitazone increases body weight through a direct inhibition of the hypothalamic melanocortin system, we studied hypothalamic neurons producing proopiomelanocortin (POMC) and the endogenous melanocortin inhibitor agouti-related peptide (AGRP), in mice expressing amyotrophic lateral sclerosis-linked mutant SOD1(G86R). We observed lower Pomc but higher Agrp mRNA levels in the hypothalamus of presymptomatic SOD1(G86R) mice. Consistently, numbers of POMC-positive neurons were decreased, whereas AGRP fibre density was elevated in the hypothalamic arcuate nucleus of SOD1(G86R) mice. Consistent with a defect in the hypothalamic melanocortin system, food intake after short term fasting was increased in SOD1(G86R) mice. Importantly, these findings were replicated in two other amyotrophic lateral sclerosis mouse models based on TDP-43 (Tardbp) and FUS mutations. Finally, we demonstrate that the melanocortin defect is primarily caused by serotonin loss in mutant SOD1(G86R) mice. Altogether, the current study combined clinical evidence and experimental studies in rodents to provide a mechanistic explanation for abnormalities in food intake and weight control observed in patients with amyotrophic lateral sclerosis. Importantly, these results also show that amyotrophic lateral sclerosis progression impairs responsiveness to classical drugs leading to weight gain. This has important implications for pharmacological management of weight loss in amyotrophic lateral sclerosis.

Platelet activation and arterial peripheral serotonin turnover in cardiac remodeling associated to aortic stenosis.

Peripheral serotonin (5-HT) has been involved in adverse cardiac remodeling and valve fibrosis. The peripheral levels of 5-HT mainly depend on its release from activated platelets and degradation by monoamine oxidase A (MAO-A). The SERAOPI study investigated the relationship between arterial serotoninergic system, degree of platelet activation and cardiac remodeling, in patients with aortic valve stenosis (AS). Thirty patients with severe AS and 15 control subjects underwent transthoracic echocardiography, radial, and aortic arterial blood sampling. Measurements of 5-HT and its MAO-A-dependent degradation product, 5-HIAA, were performed by HPLC. Arterial platelet activation was assessed by flow cytometry analysis of platelet surface expression of P-selectin and activated integrin GPIIb/IIIa. Activated platelets and arterial plasma 5-HT increased in AS patients as compared to control subjects (P-selectin 1.08 ± 0.2MFI vs. 0.49 ± 0.1MFI, P = 0.04; GPIIb/IIIa 0.71 ± 0.1MFI vs. 0.35 ± 0.1MFI; P = 0.0015 and arterial plasma 5-HT 11.55 ± 1.6 nM vs. 6.18 ± 0.7 nM, P = 0.028, respectively). Moreover, 5-HT was strongly correlated to left ventricular hypertrophy assessed by echocardiography. The correlation was independent of cardiovascular risk comorbidities and others echocardiographic AS parameters. Finally, plasma 5-HIAA increased in AS patients (74.64 ± 9.7 nM vs. 37.16 ± 4.1 nM; P = 0.0002) indicating a higher 5-HT degradation rate by MAO-A. Platelet activation, arterial circulating serotonin, and serotonin degradation increased in patients with AS. These observations suggest that the serotoninergic system may contribute to the pathogenesis of AS including valve fibrosis and adverse ventricular remodeling.

Population pharmacokinetics and haemodynamic effects of norepinephrine in hypotensive critically ill children.

AIM: The aim of the study was to investigate the pharmacokinetics and pharmacodynamics of norepinephrine in hypotensive critically ill children, including associated variability factors. METHODS: This was a prospective study in an 18-bed neonatal and paediatric intensive care unit. All children were aged less than 18 years, weighed more than 1500 g and required norepinephrine for systemic arterial hypotension. The pharmacokinetics and haemodynamic effects were described using the non-linear mixed effect modelling software MONOLIX. RESULTS: Norepinephrine dosing infusions ranging from 0.05 to 2 µg kg(-1) min(-1) were administered to 38 children whose weight ranged from 2 to 85 kg. A one compartment open model with linear elimination adequately described the norepinephrine concentration-time courses. Bodyweight (BW) was the main covariate influencing norepinephrine clearance (CL) and endogenous norepinephrine production rate (q0) via an allometric relationship: CL(BWi) = θCL × (BWi)(3/4) and q0(BWi) = θq0 × (BWi)(3/4) . The increase in mean arterial pressure (MAP) as a function of norepinephrine concentration was well described using an Emax model. The effects of post-conceptional age (PCA) and number of organ dysfunctions were significant on basal MAP level (MAP0i = MAP0 × PCA/9i (0.166) ) and on the maximal increase in MAP (32 mmHg and 12 mmHg for a number of organ dysfunctions ≤3 and ≥4, respectively). CONCLUSION: The pharmacokinetics and haemodynamic effects of norepinephrine in hypotensive critically ill children highlight the between-subject variability which is related to the substantial role of age, BW and severity of illness. Taking into account these individual characteristics may help clinicians in determining an appropriate initial a priori dosing regimen.

Pharmacokinetics, hemodynamic and metabolic effects of epinephrine to prevent post-operative low cardiac output syndrome in children.

INTRODUCTION: The response to exogenous epinephrine (Ep) is difficult to predict given the multitude of factors involved such as broad pharmacokinetic and pharmacodynamic between-subject variabilities, which may be more pronounced in children. We investigated the pharmacokinetics and pharmacodynamics of Ep, co-administered with milrinone, in children who underwent open heart surgical repair for congenital defects following cardiopulmonary bypass, including associated variability factors. METHODS: Thirty-nine children with a high risk of low cardiac output syndrome were prospectively enrolled. Ep pharmacokinetics, hemodynamic and metabolic effects were analyzed using the non-linear mixed effects modeling software MONOLIX. According to the final model, an Ep dosing simulation was suggested. RESULTS: Ep dosing infusions ranged from 0.01 to 0.23 µg.kg-1.min-1 in children whose weight ranged from 2.5 to 58 kg. A one-compartment open model with linear elimination adequately described the Ep concentration-time courses. Bodyweight (BW) was the main covariate influencing clearance (CL) and endogenous Ep production rate (q0) via an allometric relationship: CL(BWi) = θCL x (BWi)3/4 and q0(BWi) = θq0 x (BWi )3/4. The increase in heart rate (HR) and mean arterial pressure (MAP) as a function of Ep concentration were well described using an Emax model. The effect of age was significant on HR and MAP basal level parameters. Assuming that Ep stimulated the production rate of plasma glucose, the increases in plasma glucose and lactate levels were well described by turnover models without any significant effect of age, BW or exogenous glucose supply. CONCLUSIONS: According to this population analysis, the developmental effects of BW and age explained a part of the pharmacokinetic and pharmacodynamics between-subject variabilities of Ep administration in critically ill children. This approach ultimately leads to a valuable Ep dosing simulation which should help clinicians to determine an appropriate a priori dosing regimen.

Delay and stability of central venous administration of norepinephrine in children: a bench study.

UNLABELLED: In children, because of the dead volume of the central venous catheter (CVC) and the low flow rate of norepinephrine (NE) infusion, the delay between start-up and effective administration can be adversely long. A theoretical calculation enables to estimate the delay and variations of effective administration. However, numerous factors can hinder this theoretical approach. Herein, we measured via bench testing the actual delay and stability of NE administration kinetics. Using an assembly reproducing our currently-implemented catecholamine administration protocol, diluted NE (200 µg ml(-1)) was infused at an initial rate of 2 ml h(-1) (theoretically 6.67 µg min(-1)) for a period of 24 h. An assay measuring the amount of NE (µg) exiting the CVC was conducted by high-pressure liquid chromatography with colorimetric detection. The theoretical calculation of the delay in administered NE, taking into account a CVC dead volume of 0.3 ml, was 9 min. The measured percentage of the administered dose as a function of time in minutes (M) was M0-M3 (0 %), M3-M6 (0 %), M6-M9 (13 %), M9-M12 (28 %), M12-M15 (70 %), and M15-M18 (100 %) The amount of NE (µg) at fixed rate (2 ml h(-1)) was established at 6.9 ± 0.4 µg min(-1) during the 24 h. CONCLUSION: Continuous NE infusion via a CVC at low rate is stable. In children, because of CVC dead volume and low flow rate infusion, the delay in achieving intended dose delivery is significantly longer than that estimated by theoretical calculation. New modalities of initiation of catecholamine infusion adapted to the child are warranted.

p53-PGC-1α pathway mediates oxidative mitochondrial damage and cardiomyocyte necrosis induced by monoamine oxidase-A upregulation: role in chronic left ventricular dysfunction in mice.

AIMS: Oxidative stress and mitochondrial dysfunction participate together in the development of heart failure (HF). mRNA levels of monoamine oxidase-A (MAO-A), a mitochondrial enzyme that produces hydrogen peroxide (H(2)O(2)), increase in several models of cardiomyopathies. Therefore, we hypothesized that an increase in cardiac MAO-A could cause oxidative stress and mitochondrial damage, leading to cardiac dysfunction. In the present study, we evaluated the consequences of cardiac MAO-A augmentation on chronic oxidative damage, cardiomyocyte survival, and heart function, and identified the intracellular pathways involved. RESULTS: We generated transgenic (Tg) mice with cardiac-specific MAO-A overexpression. Tg mice displayed cardiac MAO-A activity levels similar to those found in HF and aging. As expected, Tg mice showed a significant decrease in the cardiac amounts of the MAO-A substrates serotonin and norepinephrine. This was associated with enhanced H(2)O(2) generation in situ and mitochondrial DNA oxidation. As a consequence, MAO-A Tg mice demonstrated progressive loss of cardiomyocytes by necrosis and ventricular failure, which were prevented by chronic treatment with the MAO-A inhibitor clorgyline and the antioxidant N-acetyl-cystein. Interestingly, Tg hearts exhibited p53 accumulation and downregulation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial function. This was concomitant with cardiac mitochondrial ultrastructural defects and ATP depletion. In vitro, MAO-A adenovirus transduction of neonatal cardiomyocytes mimicked the results in MAO-A Tg mice, triggering oxidative stress-dependent p53 activation, leading to PGC-1α downregulation, mitochondrial impairment, and cardiomyocyte necrosis. INNOVATION AND CONCLUSION: We provide the first evidence that MAO-A upregulation in the heart causes oxidative mitochondrial damage, p53-dependent repression of PGC-1α, cardiomyocyte necrosis, and chronic ventricular dysfunction.

Degeneration of serotonergic neurons in amyotrophic lateral sclerosis: a link to spasticity.

Spasticity is a common and disabling symptom observed in patients with central nervous system diseases, including amyotrophic lateral sclerosis, a disease affecting both upper and lower motor neurons. In amyotrophic lateral sclerosis, spasticity is traditionally thought to be the result of degeneration of the upper motor neurons in the cerebral cortex, although degeneration of other neuronal types, in particular serotonergic neurons, might also represent a cause of spasticity. We performed a pathology study in seven patients with amyotrophic lateral sclerosis and six control subjects and observed that central serotonergic neurons suffer from a degenerative process with prominent neuritic degeneration, and sometimes loss of cell bodies in patients with amyotrophic lateral sclerosis. Moreover, distal serotonergic projections to spinal cord motor neurons and hippocampus systematically degenerated in patients with amyotrophic lateral sclerosis. In SOD1 (G86R) mice, a transgenic model of amyotrophic lateral sclerosis, serotonin levels were decreased in brainstem and spinal cord before onset of motor symptoms. Furthermore, there was noticeable atrophy of serotonin neuronal cell bodies along with neuritic degeneration at disease onset. We hypothesized that degeneration of serotonergic neurons could underlie spasticity in amyotrophic lateral sclerosis and investigated this hypothesis in vivo using tail muscle spastic-like contractions in response to mechanical stimulation as a measure of spasticity. In SOD1 (G86R) mice, tail muscle spastic-like contractions were observed at end-stage. Importantly, they were abolished by 5-hydroxytryptamine-2b/c receptors inverse agonists. In line with this, 5-hydroxytryptamine-2b receptor expression was strongly increased at disease onset. In all, we show that serotonergic neurons degenerate during amyotrophic lateral sclerosis, and that this might underlie spasticity in mice. Further research is needed to determine whether inverse agonists of 5-hydroxytryptamine-2b/c receptors could be of interest in treating spasticity in patients with amyotrophic lateral sclerosis.

Platelet serotonin level predicts survival in amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a life-threatening neurodegenerative disease involving upper and lower motor neurons loss. Clinical features are highly variable among patients and there are currently few known disease-modifying factors underlying this heterogeneity. Serotonin is involved in a range of functions altered in ALS, including motor neuron excitability and energy metabolism. However, whether serotoninergic activity represents a disease modifier of ALS natural history remains unknown. METHODOLOGY: Platelet and plasma unconjugated concentrations of serotonin and plasma 5-HIAA, the major serotonin metabolite, levels were measured using HPLC with coulometric detection in a cohort of 85 patients with ALS all followed-up until death and compared to a control group of 29 subjects. PRINCIPAL FINDINGS: Platelet serotonin levels were significantly decreased in ALS patients. Platelet serotonin levels did not correlate with disease duration but were positively correlated with survival of the patients. Univariate Cox model analysis showed a 57% decreased risk of death for patients with platelet serotonin levels in the normal range relative to patients with abnormally low platelet serotonin (p = 0.0195). This protective effect remained significant after adjustment with age, gender or site of onset in multivariate analysis. Plasma unconjugated serotonin and 5-HIAA levels were unchanged in ALS patients compared to controls and did not correlate with clinical parameters. CONCLUSIONS/SIGNIFICANCE: The positive correlation between platelet serotonin levels and survival strongly suggests that serotonin influences the course of ALS disease.

Imatinib assay by HPLC with photodiode-array UV detection in plasma from patients with chronic myeloid leukemia: Comparison with LC-MS/MS.

BACKGROUND: Imatinib, a competitive inhibitor of BCR-ABL tyrosine kinase, is now the first-line treatment for chronic myelogenous leukemia (CML). Therapeutic drug monitoring targeting trough plasma levels of about 1000ng/mL may help to optimize the therapeutic effect. METHODS: We developed a high-performance liquid chromatography (HPLC) method with UV/Diode Array Detection (DAD) for trough imatinib concentration determination in human plasma. Imatinib trough levels were measured in plasma from 65 CML patients using our method and LC-MS/MS as the reference method. Results with these two methods were compared using Deming regression, chi-square test, and sign test. RESULTS: The calibration curve was prepared in blank human plasma. HPLC-UV/DAD calibration curves were linear from 80 to 4000ng/mL, and the limit of quantification was set at 80ng/mL. The between-day variation was 6.1% with greater than 96% recovery after direct plasma deproteinization and greater than 98% recovery from the column. No significant differences in imatinib plasma levels were found between HPLC-UV/DAD and LC-MS/MS. CONCLUSIONS: This HPLC-UV/DAD method was sufficiently specific and sensitive for imatinib TDM, with no evidence of interference. Our rapid inexpensive HPLC-UV/DAD method that requires only widely available equipment performs well for plasma imatinib assays.

Newborns' cord blood plasma cotinine concentrations are similar to that of their delivering smoking mothers.

BACKGROUND: In utero exposure to constituents of tobacco smoke has perinatal and postnatal health consequences. Umbilical cord plasma cotinine levels have been shown to correlate with self-reported daily number of cigarettes at the end of pregnancy, but the exact relationship between maternal and newborn plasma cotinine (and nicotine) is unknown. METHODS: Concentrations of cotinine, nicotine's main metabolite, were determined in venous blood of delivering mothers and in arterial umbilical cord blood of their newborns at birth. Data from eighteen mother-newborn dyads were analyzed. RESULTS: The mothers smoked 95.1 (SD=96, range 10-420) cigarettes the week preceding delivery. Their mean plasma cotinine concentration at delivery was 106 ng/mL (SD=53, range 17-245) and the newborns' mean umbilical cord plasma cotinine was 88.2 ng/mL (SD=53, range 10-198, p<0.001). The difference can be explained by the elimination time of around 6h which occurred between sampling in mothers and in umbilical cord blood. Arterial umbilical cord blood plasma cotinine was highly associated with that of the smoking mothers: y=0.79x+0.97, Rsq=0.95, p<0.001. CONCLUSIONS: Maternal and newborn plasma cotinine concentrations are strongly associated. There is probably no placental barrier for plasma cotinine between pregnant mothers and their newborns. Lack of a placental barrier for cotinine (and probably nicotine) can partially explain smoking related perinatal disorders.

Modulation of indoleamine-2,3-dioxygenase expression and activity by HIV-1 in human macrophages.

Human immunodeficiency virus (HIV) infection is often complicated by the development of acquired immunodeficiency syndrome (AIDS) dementia complex (ADC). Implications of kynurenine pathway (KP) are suggested in ADC and other inflammatories brain diseases. The first and regulatory enzyme of the KP is the indoleamine-2,3-dioxygenase (IDO). IDO activation is known to contribute to the modulation of the immune response during various infectious diseases particularly in AIDS. HIV and viral proteins can activate IDO in immune cells leading to an increase catabolism of tryptophan through the KP; the consequence being the production of immuno-modulative and neuroactive metabolites. This mechanism is likely to favour HIV persistence. The present study analysed concomitantly several parameters involved in IDO regulation and activity associated with HIV-1-infection. We investigated relevant intracellular and extracellular mechanisms involved in the regulation of IDO expression and activity during the HIV infection and replication in human monocyte-derived macrophages (MdM). Using a complementary set of in vitro experiments, we found that HIV-1/Ba-L infection induces IDO expression and increases its activity in MdM. We also showed that IDO activation by HIV-1 is likely to be a direct effect of the infection and seems to be independent of IFN-gamma production.

Reduced monoamine oxidase A activity in pregnant smokers and in their newborns.

BACKGROUND: Tobacco smoking is associated with reduced monoamine oxidase A (MAOA) activity. Smoking-associated low MAOA activities in pregnancy and in newborns may have negative perinatal and postnatal consequences. We aimed to compare, in everyday clinical conditions, biomarkers of MAOA activity in smoking (SPW) and lifetime nonsmoking pregnant women (NSPW) and in cord blood and to assess the newborns' behavior during the first 48 hours of life. METHODS: Thirty SPW and 29 NSPW in their second trimester of pregnancy were included. Plasma MAOA dependent metabolites of norepinephrine: dihydroxyphenylglycol; dopamine: homovanillic and dihydroxyphenylacetic acid; and serotonin: 5-hydroxy-indol acetic acid were measured at the end of the second trimester, at delivery, and in arterial cord blood along with plasma cotinine. The newborns' discomfort was evaluated every 8 hours by a standardized questionnaire. RESULTS: The SPW smoked, on average, 73 cigarettes per week at the end of second trimester and 80 cigarettes per week at delivery. Mean plasma cotinine was 84 ng/mL, 105 ng/mL, and 95 ng/mL at the end of second trimester, at delivery, and in cord blood, respectively (NSPW < 10 ng/mL). Plasma markers of MAOA activity, in particular those reflecting dopamine's catabolism, were significantly lower in SPW and in the arterial cord blood of their newborns than in NSPW and their newborns. Newborns of SPW showed significantly more facial discomfort than those of NSPW. CONCLUSIONS: Smoking is associated with MAOA inhibition in pregnant women and in their newborns at birth. Further studies are needed to estimate the behavioral significance of these findings.

Genetic deletion of MAO-A promotes serotonin-dependent ventricular hypertrophy by pressure overload.

The potential role of serotonin (5-HT) in cardiac function has generated much interest in recent years. In particular, the need for a tight regulation of 5-HT to maintain normal cardiovascular activity has been demonstrated in different experimental models. However, it remains unclear how increased levels of 5-HT could contribute to the development of cardiac hypertrophy. Availability of 5-HT depends on the mitochondrial enzyme monoamine oxidase A (MAO-A). Therefore, we investigated the consequences of MAO-A deletion on ventricular remodeling in the model of aortic banding in mice. At baseline, MAO-A deletion was associated with an increase in whole blood 5-HT (39.4+/-1.9 microM vs. 24.0+/-0.9 microM in KO and WT mice, respectively). Cardiac 5-HT(2A), but not 5-HT(2B) receptors were overexpressed in MAO-A KO mice, as demonstrated by real-time PCR and Western-blot experiments. After aortic banding, MAO-A KO mice demonstrated greater increase in heart wall thickness, heart to body weight ratios, cardiomyocyte cross-section areas, and myocardial fibrosis compared to WT. Exacerbation of hypertrophy in KO mice was associated with increased amounts of 5-HT in the heart. In order to determine the role of 5-HT and 5-HT(2A) receptors in ventricular remodeling in MAO-A KO mice, we administered the 5-HT(2A) receptor antagonists ketanserin (1 mg/kg/day) or M100907 (0.1 mg/kg/day) during 4 weeks of aortic banding. Chronic administration of these antagonists strongly prevented exacerbation of ventricular hypertrophy in MAO-A KO mice. These results show for the first time that regulation of peripheral 5-HT by MAO-A plays a role in ventricular remodeling via activation of 5-HT(2A) receptors.

Primary infection with simian immunodeficiency virus: plasmacytoid dendritic cell homing to lymph nodes, type I interferon, and immune suppression.

Plasmacytoid dendritic cells (pDCs) are antigen-presenting cells that develop into type-I interferon (IFN-I)-producing cells in response to pathogens. Their role in human immunodeficiency virus (HIV) pathogenesis needs to be understood. We analyzed their dynamics in relation to innate and adaptive immunity very early during the acute phase of simian immunodeficiency virus (SIV) infection in 18 macaques. pDC counts decreased in blood and increased in peripheral lymph nodes, consistent with early recruitment in secondary lymphoid tissues. These changes correlated with the kinetic and intensity of viremia and were associated with a peak of plasma IFN-I. IFN-I and viremia were positively correlated with functional activity of the immune suppression associated enzyme indoleamine-2,3-dioxygenase (IDO) and FoxP3(+)CD8(+) T cells, which both negatively correlated with SIV-specific T-cell proliferation and CD4(+) T-cell activation. These data suggest that pDCs and IFN-I play a key role in shaping innate and adaptive immunity toward suppressive pathways during the acute phase of SIV/HIV primary infection.

Lysergic acid amide-induced posterior reversible encephalopathy syndrome with status epilepticus.

INTRODUCTION: Posterior reversible encephalopathy syndrome (PRES) is known to occur in association with several substances. However, lysergic acid amide (LSA) is not among the previously reported causes of PRES. METHODS: We report on a patient with PRES presenting as convulsive status epilepticus associated with hypertensive encephalopathy after LSA ingestion. Magnetic resonance imaging was performed and catecholamine metabolites assayed. RESULTS: The patient achieved a full recovery after aggressive antihypertensive therapy and intravenous anticonvulsivant therapy. The clinical history, blood and urinary catecholamine levels, and response to treatment strongly suggest that PRES was induced by LSA. CONCLUSION: LSA, a hallucinogenic agent chiefly used for recreational purposes, should be added to the list of causes of PRES.

Comparative effects of two type I interferons, human IFN-alpha and ovine IFN-tau on indoleamine-2,3-dioxygenase in primary cultures of human macrophages.

Type I interferons (IFNs) are widely used to treat viral diseases. Depressive symptoms and suicide attempts are common neuropsychiatric side-effects during treatment with type I IFNs. Activation of indoleamine-2,3-dioxygenase (IDO), the first and rate-limiting enzyme of the kynurenine pathway by IFNs, leads to an increase in tryptophan (Trp) catabolism. Low levels of Trp lead to decrease of serotonin synthesis, which is likely to be related to the depressive symptoms. Ovine type I interferon-tau (IFN-tau) has a more potent antiretroviral effect and is less toxic than human type I IFN-alpha. Effects of IFN-tau and IFN-alpha on IDO expression and activity in primary cultures of human macrophages were compared in parallel to those of IFN-gamma, considered as one of the most potent IDO inducer. We found that both IFN-alpha and IFN-tau were poor inducers of IDO compared with IFN-gamma. However, IDO activation was slightly and significantly lower with ovine IFN-tau than human IFN-alpha, suggesting that ovine IFN-tau might have a lower impact on serotoninergic pathway compared with human IFN-alpha.

Vesicular monoamine transporter 1 mediates dopamine secretion in rat proximal tubular cells.

Renal dopamine, synthesized by proximal tubules, plays an important role in the regulation of renal sodium excretion. Although the renal dopaminergic system has been extensively investigated in both physiological and pathological situations, the mechanisms whereby dopamine is stored and secreted by proximal tubule cells remain obscure. In the present study we investigated whether vesicular monoamine transporters (VMAT)-1 and -2, which participate in amine storing and secretion, are expressed in rat renal proximal tubules, and we defined their involvement in dopamine secretion. By combining RT-PCR, Western blot, and immunocytochemistry we showed that VMAT-1 is the predominant isoform expressed in isolated proximal tubule cells. These results were confirmed by immunohistochemistry analysis of rat renal cortex showing that VMAT-1 was found in proximal tubules but not in glomeruli. Functional studies showed that, as previously reported for VMAT-dependent amine transporters, dopamine release by cultured proximal tubule cells was partially inhibited by disruption of intracellular H(+) gradient. In addition, dopamine secretion was prevented by the VMAT-1/VMAT-2 inhibitor reserpine but not by the VMAT-2 inhibitor tetrabenazine. Finally, we demonstrated that tubular VMAT-1 mRNA and protein expression were significantly upregulated during a high-sodium diet. In conclusion, our results show for the first time the expression of a VMAT in the renal proximal tubule and its involvement in regulation of dopamine secretion. These data represent the first step toward the comprehension of the role of this transporter in renal dopamine handling and its involvement in pathological situations.