Palatable high-fat diet intake influences mnemonic and emotional aspects in female rats in an estrous cycle-dependent manner.

Worldwide, the excessive consumption of fat and/or sugar has increased considerably. Palatable high-fat diets (HFDs) lead to metabolic disturbances and obesity, and impact emotional and cognitive processes. Previous studies in rodent models suggested that HFDs often cause multiple behavioral alterations, such as learning and memory deficits, and anxiety-like behaviors. Different sexes imply different behavioral and cognitive abilities; yet, most of these studies dealt with male or ovariectomized rats. We evaluated HFD effects in female rats submitted to different behavioral tasks, considering the effects of endogenous hormonal variations throughout estrous cycle. Female Wistar rats in each phase of the estrous cycle using commercial chow (CC) or HFD for 32 days. During treatment, behavioral assessments using sucrose preference (SP), elevated plus-maze (EPM), open field (OF) and novel-object recognition (NOR). At the end of the behavioral tests, animals were euthanized, and performed an immunohistochemical analysis of the brains by brain-derived neurotrophic factor (BDNF) and tyrosine hydroxylase (TH). The main results demonstrated that (1) HFD-fed rats had higher body mass gain and food intake, without altering caloric intake, (2) rats in diestrus had lower sucrose intake, (3) females in metestrus and diestrus showed deficits in the novel-object recognition memory. Furthermore, TH-immunoreactivity decreased in the dorsal striatum and BDNF in the hippocampus in HFD-fed females. These results suggest that HFD alters neurochemical and metabolic aspects that may induce phase-dependent behavioral changes in female rats.

Tyrosinemia Type 1 and symptoms of ADHD: Biochemical mechanisms and implications for treatment and prognosis.

Hereditary tyrosinemia Type 1 (HT-1) is a rare metabolic disease where the enzyme catalyzing the final step of tyrosine breakdown is defect, leading to accumulation of toxic metabolites. Nitisinone inhibits the degradation of tyrosine and thereby the production of harmful metabolites, however, the concentration of tyrosine also increases. We investigated the relationship between plasma tyrosine concentrations and cognitive functions and how tyrosine levels affected enzyme activities of human tyrosine hydroxylase (TH) and tryptophan hydroxylase 2 (TPH2). Eight Norwegian children between 6 and 18 years with HT-1 were assessed using questionnaires measuring Attention Deficit Hyperactivity Disorder (ADHD)-symptoms and executive functioning. Recent and past levels of tyrosine were measured and the enzyme activities of TH and TPH2 were studied at conditions replicating normal and pathological tyrosine concentrations. We observed a significant positive correlation between mean tyrosine levels and inattention symptoms. While TH exhibited prominent substrate inhibition kinetics, TPH2 activity also decreased at elevated tyrosine levels. Inhibition of both enzymes may impair syntheses of dopamine, noradrenaline, and serotonin in brain tissue. Inattention in treated HT-1 patients may be related to decreased production of these monoamines. Our results support recommendations of strict guidelines on plasma tyrosine levels in HT-1. ADHD-related deficits, particularly inattention, should be monitored in HT-1 patients to determine whether intervention is necessary.

Expression of classical mediators in hearts of rats with hepatic dysfunction.

Liver cirrhosis is associated with impairment of cardiovascular function including alterations of the heart innervation, humoral and nervous dysregulation, changes in systemic circulation and electrophysiological abnormalities. Choline acetyltransferase (ChAT), enzyme forming acetylcholine, tyrosine hydroxylase (TH), and dopamine-ß-hydroxylase (DBH), enzymes participating in noradrenaline synthesis, are responsible for the production of classical neurotransmitters, and atrial natriuretic peptide (ANP) is produced by cardiomyocytes. The aim of this study was to evaluate the influence of experimentally induced hepatic dysfunction on the expression of proANP, ChAT, TH, and DBH in the heart. Hepatic dysfunction was induced by application of thioacetamide (TAA) or by ligation of bile duct. Biochemical parameters of hepatic injury and levels of peroxidation in the liver and heart were measured. Liver enzymes measured in the plasma were significantly elevated. Cardiac level of peroxidation was increased in operated but not TAA group animals. In the left atrium of operated rats, the expression of TH and DBH was lower, while expression of ChAT remained unchanged. In TAA group, no significant differences in the expression of the genes compared to controls were observed. Liver injury induced by ligation leads to an imbalance in the intracardiac innervation, which might impair nervous control of the heart.

Clinical Significance of Tyrosine Hydroxylase mRNA Transcripts in Peripheral Blood at Diagnosis in Patients with Neuroblastoma.

PURPOSE: The purpose of this study is to investigate the clinical significance of tyrosine hydroxylase (TH) expression in peripheral blood (PB) at diagnosis in patients with neuroblastoma. MATERIALS AND METHODS: TH mRNA expression in PB was measured by reverse transcription quantitative real-time polymerase chain reaction in 210 patients who were newly diagnosed with neuroblastoma from July 2005 to June 2015 and the clinical significance of TH expression in PB at diagnosis was evaluated. RESULTS: TH expression was positive in 60 patients (28.6%). Fifty of 60 TH-positive patients had metastatic tumors and the remaining 10 had localized tumors. TH expression was associated with high-risk features (i.e., advanced stage, older age, unfavorable pathology, and MYCN amplification) at diagnosis. Among TH-positive patients, higher TH expression level was observed in high-risk patients than in low- or intermediate-risk patients (p=0.035). The probability of 5-year progression-free survival (PFS) was lower in TH-positive patients than in TH-negative patients (63.8±6.9% vs. 94.7±2.1%, p < 0.001). In analysis confined to high-risk patients, the 5-year probability of PFS remained lower in TH-positive patients (55.7±8.2% vs. 89.6±5.8%, p < 0.001). Among TH-positive patients, a higher expression level of TH was associated with a worse outcome. In multivariate analyses, positive TH expression in PB at diagnosis was an independent poor prognostic factor for PFS. CONCLUSION: The treatment intensity should be tailored according to TH expression in PB at diagnosis.

Dopaminergic Receptors and Tyrosine Hydroxylase Expression in Peripheral Blood Mononuclear Cells: A Distinct Pattern in Central Obesity.

BACKGROUND: Dopamine (DA) may be involved in central obesity (CO), an inflammatory condition, through its role in the central nervous system and in periphery, where it may affect immune cell function through five different DA receptors (DR). Whether dopaminergic pathways in peripheral immune cells are implicated in the inflammatory condition linked to CO is however unknown. METHODS: In a cohort of blood donors with and without CO, categorized by waist circumference (WC) (CO: WC ≥ 0.80 m in women and ≥ 0.94 m in men), we studied the expression of DR and tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of DA, in peripheral blood mononuclear cells (PBMCs) and their relation with anthropometric and metabolic/endocrine and inflammatory parameters. DR D1-5 and TH expression was assessed by semi quantitative real-time PCR. As inflammatory markers we investigated the immunophenotype of monocyte subsets by flow cytometry, staining for CD14, CD16, CD11b and CD36. RESULTS: CO individuals showed higher plasma levels of leptin and higher inflammatory pattern of monocytes compared with non-CO. PBMC expression of DR D2, DR D4 and DR D5 as well as of TH were lower in CO in comparison with non-CO. DR D2, and DR D5 expression correlated with lower WC and weight, and with lower inflammatory pattern of monocytes, and TH expression correlated with lower WC. DR D4 expression correlated with lower plasma levels of glycosylated hemoglobin, and DR D2 expression correlated with lower CO. CONCLUSIONS: Results show that CO is associated with peripheral inflammation and downregulation of dopaminergic pathways in PBMCs, possibly suggesting DR expressed on immune cells as pharmacological targets in obesity for better metabolic outcome.

TH and DCX mRNAs in peripheral blood and bone marrow predict outcome in metastatic neuroblastoma patients.

PURPOSE: In metastatic neuroblastoma (NB) patients, accurate risk stratification and disease monitoring would reduce relapse probabilities. This study aims to evaluate the independent prognostic significance of detecting tyrosine hydroxylase (TH) and doublecortin (DCX) mRNAs by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) in peripheral blood (PB) and bone marrow (BM) samples from metastatic NB patients. PROCEDURES: RT-qPCR was performed on PB and BM samples from metastatic NB patients at diagnosis, post-induction therapy and at the end of treatment for TH and DCX mRNAs detection. RESULTS: High levels of TH and DCX mRNAs when detected in PB and BM at diagnosis independently predicted worse outcome in a cohort of 162 metastatic NB. In the subgroup of high-risk metastatic NB, TH mRNA detected in PB remained as independent predictor of EFS and OS at diagnosis. After the induction therapy, high levels of TH mRNA in PB and DCX mRNA in BM independently predicted poor EFS and OS. Furthermore TH mRNA when detected in BM predicted worse EFS. TH mRNA in PB samples at the end of treatment is an independent predictor of worse outcome. CONCLUSION: TH and DCX mRNAs levels in PB and BM assessed by RT-qPCR should be considered in new pre-treatment risk stratification strategies to reliable estimate outcome differences in metastatic NB patients. In those high-risk metastatic NB, TH and DCX mRNA quantification could be used for the assessment of response to treatment and for early detection of progressive disease or relapses.

Coadministration of ß-asarone and levodopa increases dopamine in rat brain by accelerating transformation of levodopa: a different mechanism from Madopar.

The aim of the present study was to investigate the effect of coadministration of ß-asarone and levodopa (l-dopa) on increasing dopamine (DA) in the striatum of healthy rats. Rats were randomly divided into four groups: (i) a normal group, administered normal saline; (ii) a Madopar group, administered 75 mg/kg Madopar (l-dopa : benserazide, 4 : 1); (iii) an l-dopa group, administered 60 mg/kg l-dopa; and (iv) a group coadministered 15 mg/kg ß-asarone and 60 mg/kg l-dopa. All drugs (or normal saline) were administered intragastrically twice a day for 7 days. Then, plasma and striatum concentrations of DA, l-dopa, 5-hydroxytryptamine (5-HT), homovanillic acid (HVA), 3,4-dihydroxyphenylacetic acid (DOPAC), tyrosine hydroxylase (TH), catechol-O-methyltransferase (COMT) and monoamine oxidase B (MAO-B) were determined. In the group coadministered ß-asarone and l-dopa, there was a decline in plasma and striatal concentrations of l-dopa; however, DA and DOPAC concentrations increased in the striatum and plasma and plasma HVA concentrations increased, whereas there was no significant change in striatal levels. Concentrations of 5-HT in the striatum and plasma were similar in the coadministered and Madopar-treated groups. In addition, plasma and striatal COMT levels decreased after coadministration of ß-asarone and l-dopa, whereas there were no significant differences in MAO-B concentrations among groups. Furthermore, coadministration of ß-asarone and l-dopa increased plasma TH concentrations. Altogether, ß-asarone affects the conversion of l-dopa to DA by modulating COMT activity and DA metabolism. The mechanism of coadministration is different from that of Madopar in Parkinson's disease (PD) treatment. Thus, the coadministration of ß-asarone and l-dopa may be beneficial in the treatment of PD.

Minimal disease detection in peripheral blood and bone marrow from patients with non-metastatic neuroblastoma.

PURPOSE: In non-metastatic neuroblastoma (NB), the identification of the cases that require more intensive treatment is still difficult. Minimal disease (MD) and minimal residual disease (MRD) detection in outcome prediction seems to be important in advanced neuroblastoma, but there are not many studies focused on patients with non-metastatic disease. The aim of this study was to determine whether the presence of MD detected at diagnosis could be associated with bad prognosis. PROCEDURES: Quantitative reverse transcriptase-polymerase chain reaction QRT-PCR was performed on peripheral blood (PB) and bone marrow (BM) samples from patients with non-metastatic NB at diagnosis for tyrosine hydroxylase (TH) and doublecortin (DCX) mRNAs detection. RESULTS: The frequencies of detecting MD in our series of 102 patients with non-metastatic NB were as follows: 6.2% (5/81) PB samples and 10.6% (10/94) BM samples. Overall survival was similar for patients who expressed or not the MD biomarkers at diagnosis. However, patients with MD detected in PB showed lower EFS than patients with negative PB (P = 0.038). CONCLUSIONS: Minimal disease detection in PB seems to be useful for predicting relapse probabilities in patients with non-metastatic NB. The stages 1 and 2 patients with neuroblastoma showed high survival rates, and MD was detected in a small number of patients probably being non-contributory for predicting patient outcome. For stage 3 patients with NB, MD detection by QRT-PCR in PB at diagnosis could be useful for predicting outcome and for early and sensitive detection of relapsing disease.

Molecular detection of tyrosine hydroxylase in the peripheral blood of patients with neuroblastoma: useful at diagnosis but not predictive of subsequent relapse during off-therapy follow-up.

In the present study, the authors analyzed the tyrosine hydroxylase (TH) expression in peripheral blood (PB) of neuroblastoma (NB) patients and investigated the clinical implications. From April 2005 to October 2008, a total of 683 PB specimens (64 at diagnosis, 244 during chemotherapy, 355 during off-therapy follow-up, and 20 at relapse) acquired from 141 patients were investigated. TH expression was measured by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). TH-positive rate at diagnosis (21.4%) was higher than those during chemotherapy (0.8%) or off-therapy follow-up (1.7%). TH expression at diagnosis was associated with high-risk features (ie, advanced stage, older age, unfavorable pathology, and amplified N-myc) and the probability of 3-year relapse-free survival in the TH-positive patients was lower than in the TH-negative patients (45.8% ± 27.8% versus 95.8% ± 5.7%, P < .001). TH expression was positive in only 6 specimens during off-therapy follow-up. However, tumor relapse occurred in only 2 out of 6 TH-positive patients. In addition, TH expression was negative during previous off-therapy follow-up, prior to relapse, in 8 out of 10 relapsed patients. Whereas TH expression in PB at diagnosis was associated with high-risk features and a poorer outcome, TH expression during off-therapy follow-up had very limited value for the prediction of a subsequent relapse.

[The mRNA expression levels of IL-1beta, TNF-alpha and tyrosine hydroxylase in peripheral blood of paranoid schizophrenic patients].

AIM: To investigate the gene expression levels of interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and tyrosine hydroxylase (TH) in peripheral blood of paranoid schizophrenic patients, and explore the neuroimmunological mechanism of paranoid schizophrenia. METHODS: The mRNA expression levels of IL-1beta, TNF-alpha and TH in the peripheral blood of 39 paranoid schizophrenic patients and 30 normal controls were measured with RT-PCR and semi-quantitative technique. RESULTS: The mRNA expression levels of IL-1beta, TNF-alpha and TH was higher in paranoid schizophrenic patients than those in normal controls (P<0.01). The correlation between the gene expression levels of IL-1beta and TH was found in normal controls (r=0.666, P<0.01), not in paranoid schizophrenic patients (P>0.05); and the correlation between the gene expression levels of IL-1beta and TNF-alpha was significant in all groups (r=0.847 for normal controls and 0.942 for patients, P<0.01, respectively). CONCLUSION: Pro-inflammation cytokines and catecholamines have been demonstrated to be overexpressed in the peripheral blood of paranoid schizophrenic patients. And the correlation between catecholamines and pro-inflammation cytokines, which exists in the controls, is broken in paranoid schizophrenic patients.

Prognostic impact of the detection of microcirculating tumor cells by a real-time RT-PCR assay of tyrosine hydroxylase in patients with advanced neuroblastoma.

Molecular detection of microcirculating or microdisseminated disease (MDD) with a sensitive methodology could contribute to a better treatment for children with neuroblastoma. To detect circulating neuroblastoma cells, we developed a quantitative assay for the analysis of tyrosine hydroxylase (TH) gene expression. We analyzed 155 samples of peripheral blood (PB) from 25 patients with neuroblastoma in advanced stages (8 stage III and 17 stage IV). TH mRNA was analyzed by RT-PCR assay using TaqMan technology. PB samples (n=25) from donors were used for normalizing TH, and values <7 were considered negative. With a median follow-up of 40 months (range 15-73 months), 9 patients relapsed and 8 patients died of progressive disease. TH expression was detected in the PB of 16 patients (64%) at diagnosis. During treatment, 10 patients had positive samples and 9 patients were still positive for circulating tumor cells at the end of treatment. Actuarial 3-year event-free survival of patients with PB positive for TH mRNA after induction therapy (40%) (p=0.018) and at the completion of treatment (33%) (p=0.003) were significantly worse than the survival of TH-negative patients (86 and 87%, respectively). In multivariate analysis, MYCN status and TH expression in PB at the end of treatment remained significant prognostic factors. Our results show that patients with advanced neuroblastoma who have PB positive for TH at the end of treatment seem to have a worse prognosis compared with patients with undetectable TH. These results suggest the usefulness of MDD monitoring in neuroblastoma.

[New criteria for prediction of individual endurance of physical stress]. / Novye kriterii prognoza individual'noi ustoichivosti k fizicheskim nagruzkam.

A team of eight triathlon athletes was tested for endurance to extreme physical stress during training session. Two new functional parameters were analyzed, i.e. the cell membrane beta-adrenoreactivity (beta-ARM) and activity of leukocyte tyrosine hydroxilase (TH) as a key enzyme of the dophaminergic system. In four athletes who had been included in the national team at a later date beta-ARM and Kth values were 2-3-fold beyond the physiological norm, whereas in the other four (reserves) the parameters were below the upper limits. These data suggest that abnormal beta-ARM and Kth values can be treated as biochemical prognostic criteria for endurance of extreme phyical stress.

Changes in the concentrations of tetrahydrobiopterin, the cofactor of tyrosine hydroxylase, in blood under physical stress and in depression.

This paper studies changes in the concentrations of tetrahydrobiopterin (BH4), the cofactor of tyrosine hydroxylase, in blood under physical stress and in depression. BH4 was found to be transiently released from the sympathetic nerves under severe physical stress but continuously released in depression with an increased oxidation rate of BH4 to B.

Effects of different forms of environmental enrichment on behavioral, endocrinological, and immunological parameters in male mice.

This study investigated effects of different forms of environmental enrichment on behavioral, endocrinological, and immunological parameters in male mice. For this purpose, animals of the inbred strain CS were kept in groups of four males under three different housing conditions: (A) nonstructured Makrolon type III laboratory cages ("standard-housing" = S); (B) equivalent laboratory cages that were enriched with a box and a scaffolding ("enriched-housing" = E); and (C) spacious terraria that were structured richly ("super-enriched-housing" = SE). Both forms of enrichment caused a sharp rise in aggressive behavior, though play behavior was increased in E and SE mice, too. Levels of sociopositive behaviors in S and SE mice were higher than those in E mice. Plasma corticosterone concentrations and adrenal tyrosine hydroxylase activities were significantly increased in male mice kept in both forms of enriched cages, indicating an activation of the pituitary-adrenocortical and the adrenomedullary systems. The behavioral and endocrinological differences were partly reflected by immunological parameters: SE mice had levels of IgG1 and ratios of IFN-gamma/IL-10 and IL-2/IL-10 significantly lower than those of S mice. Ratios of IgG2a/IgG1 were significantly higher in SE mice. The absolute percentages of CD8 cells in E-mice were significantly lower than those in S mice. Despite the elevated levels of stress hormones under both forms of enriched housing, the behavioral parameters also indicate positive effects of the enrichment, especially on SE animals. Obviously, an environmental enrichment is beneficial for male mice as long as the spatial conditions are generous enough to allow coping with the increased aggression brought about by the enrichment.

Quantitative analysis of tyrosine hydroxylase mRNA for sensitive detection of neuroblastoma cells in blood and bone marrow.

BACKGROUND: Sensitive monitoring of minimal residual disease may improve the treatment of neuroblastoma in children. To detect and monitor neuroblastoma cells in blood and bone marrow, we developed a quantitative method for the analysis of tyrosine hydroxylase mRNA. METHODS: We used real-time reverse transcription-PCR. The calibrator was constructed from a segment of tyrosine hydroxylase mRNA that included the target. Blood and bone marrow samples from 24 children with neuroblastoma and 1 child with ganglioneuroma were analyzed. Controls were blood samples from the cords of 40 babies, from 58 children 6 months to 15 years of age, and from 34 healthy adults, as well as from 12 children with other diseases. RESULTS: The detection limit was approximately 70 transcripts/mL. All 144 blood controls were below this limit. At diagnosis, blood tyrosine hydroxylase mRNA was higher in children with widespread disease (stage 4/4S; n = 6; range, 203-46,000 transcripts/mL) than in patients with localized disease (stages 1-3; n = 6;

Ultrastructural localization of tyrosine hydroxylase in human peripheral blood mononuclear cells: effect of stimulation with phytohaemagglutinin.

Using immunocytochemistry coupled to fluorescence and electron microscopy, we investigated the expression and ultrastructural localization of tyrosine hydroxylase (TH, EC 1.14.16.2), the rate-limiting enzyme in the biosynthesis of catecholamines, in human peripheral blood mononuclear cells (PBMCs), with PC12 cells as positive controls. In unstimulated PBMCs, TH-specific immunoreactivity was localized to the plasma membrane. However, after stimulation with the polyclonal mitogen phytohaemagglutinin (PHA), TH immunoreactivity was almost completely localized to electron-dense cytoplasmic granules, which resembled those found in PC12. TH-positive granules, however, were larger (300-500 nm) than in PC12 cells (100-200 nm). Flow cytometry analysis of TH expression showed about 46-50% positive cells in unstimulated PBMCs and in PHA-stimulated PBMCs in the G0/G1 phase of the cell cycle, but more than 80% positive cells in PHA-stimulated PBMCs in the S+G2/M phase. In agreement with previous observations, PHA stimulation also induced de novo expression of TH mRNA as well as increased intracellular catecholamine content, suggesting the occurrence of TH upregulation at the level of both gene expression and enzyme activity. The ultrastructural localization of TH in human PBMCs seems therefore regulated by cell stimulation and related to the functional activity of the enzyme.

Detection procedures for neuroblastoma cells metastatic to blood and bone marrow: blinded comparison of chromogranin A heminested reverse transcription polymerase chain reaction to tyrosine hydroxylase nested reverse transcription polymerase chain reaction and to anti-GD2 immunocytology.

Specific and sensitive tumor cell detection is becoming increasingly important for diagnosing and staging as well as for the therapeutic management of neuroblastoma patients. We propose a chromogranin A heminested reverse transcription polymerase chain reaction (CgA hn RT-PCR) procedure for the detection of neuroblastoma minimal residual disease in peripheral blood and bone marrow samples. The results were checked in comparison with the presently available procedures (i.e., with the tyrosine hydroxylase nested RT-PCR [TH n RT-PCR] and with the immunocytochemical approach using anti-GD2 antibodies). Controls from healthy patients or from people with unrelated disease (12 samples of bone marrow and 23 samples of peripheral blood) and serial dilution experiments using neuroblastoma cell lines (SKNLP, SKNFI, STA6, STA8) showed CgA hn RT-PCR full specificity and sensitivity ranging from 10(3) to 10(6) (depending on the cell line). The results compared favorably with those obtained using TH n RT-PCR. Preliminary data obtained analyzing bone marrow and peripheral blood specimens from stage IV neuroblastomas showed substantially overlapping results between CgA and TH n RT-PCR procedures. Our data support the potential usefulness of CgA heminested RT-PCR as a specific and sensitive procedure for minimal disease detection in neuroblastoma. A prospective evaluation of this tool in clinical studies might be warranted.

Modulation of aggression in male mice: influence of group size and cage size.

Aggression in group-housed male mice is known to be influenced by both cage size and group size. However, the interdependency of these two parameters has not been studied yet. In this study, the level of aggression in groups of three, five, or eight male BALB/c mice housed in cages with a floor size of either 80 or 125 cm(2)/animal was estimated weekly after cage cleaning for a period of 14 weeks. Furthermore, urine corticosterone levels, food and water intake, body weight, and number of wounds were measured weekly. At the end of the experiment, tyrosine hydroxylase (TH) activity, testosterone levels, and weight of spleen, thymus, testes, and seminal vesicles were determined. Results indicate a moderate increase of intermale aggression in larger cages when compared to the smaller cages. Aggression in groups of eight animals was considerably higher than in groups of three animals. The increase of agonistic behavior was observed both in dominant and subordinate animals. Physiological parameters indicate differences in stress levels between dominant and subordinate animals. It is concluded that aggressive behavior in group-housed male BALB/c mice is best prevented by housing the animals in small groups of three to five animals, while decreasing floor size per animal may be used as a temporary solution to decrease high levels of aggression in an existing social group.

Endogenous catecholamine synthesis, metabolism storage, and uptake in human peripheral blood mononuclear cells.

Evidence has been obtained that peripheral blood mononuclear cells contain dopamine, norepinephrine, epinephrine, and their metabolites. Pharmacologic inhibition of tyrosine hydroxylase or monoamine oxidase profoundly affected intracellular catecholamines (CTs) and their metabolites, indicating that these cells are able to synthesize and breakdown CTs. The sensitivity of intracellular CTs to reserpine and the presence of CTs in the extracellular medium suggest that CTs are stored and released. Moreover, the increase of extracellular CTs in the presence of monoamine uptake blockers point to the presence of functional uptake mechanisms. Altogether, these results indicate the existence of a CT lifecycle in human mononuclear cells and warrant further studies to investigate the role of adrenergic autoregulatory mechanisms in modulation of the immune response and in the pathogenesis of diseases involving the immune system.

Serum tyrosine hydroxylase activity is increased in melanoma patients. An ROC curve analysis.

We have studied the serum tyrosine hydroxylase activity of tyrosinase, the key enzyme in the melanogenesis via, as a possible diagnostic factor or marker for detection, prognosis and follow-up of patients with melanoma. This activity was determined in 30 melanoma patients (MP) and in 30 healthy persons (HP) by using a radiometric method. We found mean values of 10.8+/-3.0 and 7.65+/-2.32 mU/l for serum tyrosine hydroxylase activity in MP and HP, respectively. A very significant increase in serum tyrosine hydroxylase activity was observed in MP in comparison to the enzymatic activity in HP (P < 0.00001). Although these data seem very conclusive, we wanted to know whether this test could discriminate adequately between MP and HP. In order to reach this aim, a complete statistical study was performed by using receiver operating characteristic (ROC) curve analysis. The cut-off value obtained was 8.47 mU/l. According to our results and after analytical treatment of the data, we can confirm that evaluation of tyrosine hydroxylase activity in serum could be a quick and reliable diagnostic method for detection, prognosis and follow-up in melanoma patients.