Alpha-methyltyrosine reduces the acute cardiovascular and behavioral sequelae in a murine model of traumatic brain injury.

BACKGROUND: Increased catecholamines contribute to heightened cardiovascular reactivity and behavioral deficits after traumatic brain injury (TBI); adrenergic receptor blockade has limited success in reducing adverse sequelae of TBI. Injury-induced increases in the synthesis of catecholamines could contribute to adverse outcomes in TBI. Inhibition of catecholamine synthesis with alpha-methyltyrosine (αMT) could offer a benefit after TBI. METHODS: Original research trial in mice randomized to αMT (50 mg·kg -1 ·d -1 ) or vehicle for 1 week after TBI induced by controlled cortical impact. Primary outcomes of cardiovascular reactivity and behavioral deficits were assessed after 1 week. Secondary outcomes included blood brain barrier permeability and quantification of gene transcription whose products determine intraneuronal chloride concentrations, the release of catecholamines, and activation of the sympathetic nervous system. These genes were the alpha-2 adrenergic receptor ("Adra2c"), the sodium-potassium-chloride cotransporter ("Nkcc1"), and the potassium chloride cotransporter ("Kcc2"). We also assessed the effect of TBI and αMT on the neuronal chloride/bicarbonate exchanger ("Ae3"). RESULTS: Traumatic brain injury-induced increases in blood pressure and cardiac reactivity were blocked by αMT. Inhibition of catecholamine synthesis decreased blood brain barrier leakage and improved behavioral outcomes after TBI. Traumatic brain injury diminished the transcription of Adra2c and enhanced expression of Nkcc1 while reducing Kcc2 transcription; αMT prevented the induction of the Nkcc1 by TBI without reversing the effects of TBI on Kcc2 expression; αMT also diminished Ae3 transcription. CONCLUSION: Traumatic brain injury acutely increases cardiovascular reactivity and induces behavioral deficits in an αMT-sensitive manner, most likely by inducing Nkcc1 gene transcription. Alpha-methyltyrosine may prove salutary in the treatment of TBI by attenuating the enhanced expression of Nkcc1, minimizing blood brain barrier leakage, and diminishing central catecholamine and sympathetic output. We also found an unreported relationship between Kcc2 and the chloride/bicarbonate exchanger, which should be considered in the design of trials planned to manipulate central intraneuronal chloride concentrations following acute brain injury.

The effects of metyrosine on ischemia-reperfusion-induced oxidative ovarian injury in rats: Biochemical and histopathological assessment.

The aim of this study is to investigate the effect of metyrosine on ischemia-reperfusion (I/R) induced ovarian injury in rats in terms of biochemistry and histopathology. Rats were divided into: ovarian I/R (OIR), ovarian I/R+50 mg/kg metyrosine (OIRM) and sham (SG) operations. OIRM group received 50 mg/kg metyrosine one hour before the application of the anesthetic agent, OIR and SG group rats received equal amount of distilled water to be used as a solvent orally through cannula. Following the application of the anesthetic agent, ovaries of OIRM and OIR group rats were subjected to ischemia and reperfusion, each of which took two hours. This biochemical experiment findings revealed high levels of malondialdehyde (MDA) and cyclo-oxygenase-2 (COX-2) and low levels of total glutathione (tGSH), superoxide dismutase (SOD) and cyclo-oxygenase-1 (COX-1) in the ovarian tissue of OIR group, with significant histopathological injury. In metyrosine group, MDA and COX-2 levels were lower than the OIR group whereas tGSH, SOD and COX-1 levels were higher, with slighter histopathological injury. Our experimental findings indicate that metyrosine inhibits oxidative and pro-inflammatory damage associated with ovarian I/R in rats. These findings suggest that metyrosine could be useful in the treatment of ovarian injury associated with I/R.

Validation of the forced swim test in Drosophila, and its use to demonstrate psilocybin has long-lasting antidepressant-like effects in flies.

Psilocybin has been shown to be a powerful, long-lasting antidepressant in human clinical trials and in rodent models. Although rodents have commonly been used to model psychiatric disorders, Drosophila have neurotransmitter systems similar to mammals and many comparable brain structures involved in similar behaviors. The forced swim test (FST), which has been used extensively to evaluate compounds for antidepressant efficacy, has recently been adapted for Drosophila. The fly FST has potential to be a cost-effective, high-throughput assay for evaluating potential antidepressants. For this study we pharmacologically validated the fly FST using methamphetamine, DL-α-methyltyrosine, and the antidepressant citalopram. While methamphetamine and DL-α-methyltyrosine altered overall locomotor activity in the Drosophila Activity Monitor System (DAMS), they had no significant impact on measures of immobility in the FST. Conversely, chronic citalopram decreased measures of immobility in the FST in both sexes without increasing DAMS activity. We used the validated FST to evaluate the antidepressant-like effects of high (3.5 mM) and low (0.03 mM) doses of psilocybin. Both doses of psilocybin significantly reduced measures of immobility in male flies, but not females. 0.03 mM had an effect size comparable to chronic citalopram, and 3.5 mM had an effect size approximately twice that of chronic citalopram.

Enhancing the accumulation level of 3-[18F]fluoro-L-α-methyltyrosine in tumors by preloading probenecid.

INTRODUCTION: 3-[18F]fluoro-α-methyl-L-tyrosine ([18F]FAMT) is a promising amino acid tracer targeting L-type amino acid transporter 1 (LAT1). One concern regarding the diagnosis using [18F]FAMT is the possibility of false-negative findings because of its relatively low accumulation level even in malignant tumors. Moreover, preloading probenecid, an organic anion transporter inhibitor, markedly increased the tumor accumulation level of radioiodine-labeled α-methyltyrosine. In this study, we evaluated the usefulness of preloading probenecid in improving the tumor-imaging capability of [18F]FAMT. METHODS: Three biodistribution studies of [18F]FAMT were conducted in normal mice to elucidate the usefulness of probenecid preloading. Later, a biodistribution study and positron emission tomography (PET) imaging of [18F]FAMT were conducted with or without probenecid injection in tumor-bearing mice. RESULTS: Probenecid preloading significantly delayed blood clearance and consequently enhanced the accumulation of [18F]FAMT in the pancreas, a LAT1-positive organ. The effects of probenecid preloading were independent of the administration route. Tumor accumulation level in the biodistribution study and the maximum standardized uptake value in tumors on PET imaging of the probenecid preloading group were significantly higher than those of the control (without probenecid injection) group in tumor-bearing mice. CONCLUSIONS: Preloading probenecid significantly delayed blood clearance and consequently enhanced the accumulation of [18F]FAMT in tumors. These results indicate that preloading probenecid could improve the diagnostic accuracy of [18F]FAMT.

Involvement of dopamine D2 and glutamate NMDA receptors in the antidepressant-like effect of amantadine in mice.

The present study investigated the pharmacological mechanisms of the antidepressant-like effects of amantadine in mice and their influence on hippocampal neurogenesis. To improve the translational validity of preclinical results, reproducibility across laboratories and replication in other animal models and species are crucial. Single amantadine administration at doses of 50 and 75 mg/kg resulted in antidepressant-like effects in mice in the tail suspension test (TST), reflected by an increase in immobility time. The effects of amantadine were seen at doses that did not alter locomotor activity. The tyrosine hydroxylase inhibitor α-methyl-ρ-tyrosine did not influence the anti-immobility effect of amantadine in the TST. Pretreatment with the α1 adrenergic receptor antagonist prazosin, ß adrenergic receptor antagonist propranolol, α2 adrenergic receptor antagonist yohimbine, and α2 adrenergic receptor agonist clonidine did not alter the antidepressant-like effect of amantadine. However, amantadine's effect was blocked by the dopamine D2 receptor antagonist haloperidol and glutamate receptor agonist N-methyl-D-aspartate (NMDA). Repeated amantadine administration (50 mg/kg) also exerted an antidepressant-like effect, paralleled by an increase in hippocampal neurogenesis. The present results demonstrate that the antidepressant-like effects of amantadine may be mediated by its actions on D2 and NMDA receptors and likely involve hippocampal neurogenesis.

5-HT1A Serotonergic, α-Adrenergic and Opioidergic Receptors Mediate the Analgesic Efficacy of Vortioxetine in Mice.

Vortioxetine is a multimodal antidepressant drug that affects several brain neurochemicals and has the potential to induce various pharmacological effects on the central nervous system. Therefore, we investigated the centrally mediated analgesic efficacy of this drug and the mechanisms underlying this effect. Analgesic activity of vortioxetine (5, 10 and 20 mg/kg, p.o.) was examined by tail-clip, tail-immersion and hot-plate tests. Motor performance of animals was evaluated using Rota-rod device. Time course measurements (30-180 min) showed that vortioxetine (10 and 20 mg/kg) administrations significantly increased the response latency, percent maximum possible effect and area under the curve values in all of the nociceptive tests. These data pointed out the analgesic effect of vortioxetine on central pathways carrying acute thermal and mechanical nociceptive stimuli. Vortioxetine did not alter the motor coordination of mice indicating that the analgesic activity of this drug was specific. In mechanistic studies, pre-treatments with p-chlorophenylalanine (serotonin-synthesis inhibitor), NAN-190 (serotonin 5-HT1A receptor antagonist), α-methyl-para-tyrosine (catecholamine-synthesis inhibitor), phentolamine (non-selective α-adrenoceptor blocker), and naloxone (non-selective opioid receptor blocker) antagonised the vortioxetine-induced analgesia. Obtained findings indicated that vortioxetine-induced analgesia is mediated by 5-HT1A serotonergic, α-adrenergic and opioidergic receptors, and contributions of central serotonergic and catecholaminergic neurotransmissions are critical for this effect.

Effect of levodopa/carbidopa on stress response in zebrafish.

The dopaminergic system of zebrafish is complex and the numerous pathways and receptors in the central nervous system (CNS) are being extensively studied. A critical factor for the synthesis, activation and release of catecholamines (CAs) is the presence of tyrosine hydroxylase, an enzyme which converts L-tyrosine into levodopa. Levodopa thus is the intermediary in the synthesis of dopamine (DA) and norepinephrine (NE) and promotes its release; therefore, CAs play an important role in the CNS with hormonal functions. Here, we use levodopa/carbidopa to clarify the involvement of the dopaminergic pathway in the stress response in zebrafish submitted to an acute stress challenge. Acute stress was induced by chasing fish with a net for 2 min and assessed by measuring whole-body cortisol levels. Two experiments were carried out, the first with exposure to levodopa/carbidopa and the second with exposure to AMPT and levodopa/carbidopa. Levodopa/carbidopa balances the stress response through its action on the zebrafish hypothalamic-pituitary-adrenal (HPA) axis. Changes in cortisol levels suggest that DA was related to the balance of the stress response and that NE decreased this response. These effects were specific to stress since levodopa/carbidopa did not induce changes in cortisol in non-stressed fish.

The Role for Metyrosine in the Treatment of Patients With Pheochromocytoma and Paraganglioma.

CONTEXT: Treatment of pheochromocytoma and paraganglioma (PPGL) requires preintervention titration of alpha- and beta-adrenergic blockade, but patients may still be at risk for complications from catecholamine excess. Metyrosine decreases catecholamine production, making it an attractive therapeutic adjunct for select patients. EVIDENCE ACQUISITION: A systematic literature review was performed (Ovid Medline and Scopus databases) on December 17, 2019, including studies with humans and original data. Studies with 10 or more patients on metyrosine for PPGL were included. Studies were screened for overlapping populations, and the most comprehensive study was included. The references of included studies were reviewed for additional data. Patient data from our institution between 2000 and 2015 were also reviewed. EVIDENCE SYNTHESIS: Metyrosine is well tolerated when used for a short course and can improve intraoperative outcomes in PPGL. Metyrosine should be considered when a difficult PPGL resection is expected (eg, pericardiac paraganglioma, abdominal paraganglioma with great vessel involvement), a large release of catecholamines is anticipated (eg, ablative therapy, chemotherapy), or when standard alpha- and beta-adrenergic blockade are not tolerated or cannot adequately control hypertension. Side effects are generally mild and self-limited, with sedation in a majority of patients. Extrapyramidal side effects are rare but can limit use of metyrosine. Because of its expense and limited availability, metyrosine use should be carefully planned and timed in relation to surgery. CONCLUSIONS: Metyrosine is a safe addition to traditional alpha- and beta-adrenergic blockade and should be considered in those patients with PPGL at high risk for acute release of catecholamines.

Image screening for maxillo-mandibular actinomycosis with CT, 18F-FDG-PET/CT, and 18F-α-methyl tyrosine PET/CT.

OBJECTIVES: Clinical features and imaging findings of maxillo-mandibular actinomycosis are similar to those of intraosseous carcinoma. The purpose of this study is to clarify the characteristics of the imaging findings for screening of maxillo-mandibular actinomycosis using CT and PET. METHODS: Reports on maxillo-mandibular actinomycosis published between 1997 and 2016 were searched in PubMed using "actinomycosis," "maxilla," and "mandibular" as keywords. Ten cases suspected to have malignant tumors on diagnostic imaging findings were selected. In addition, three patients who visited Gunma University Hospital were also included. The 13 total cases were subjected to a pooled analysis of diagnostic screening of maxillo-mandibular actinomycosis using CT, 18F-FDG-PET/CT (FDG-PET/CT) and 18F-α-methyl tyrosine PET/CT (FAMT-PET/CT). Additionally, cases of intraosseous carcinoma were analyzed as comparative controls to investigate the difference between maxillo-mandibular actinomycosis and intraosseous carcinoma on CT imaging. RESULTS: CT images of the 13 cases with maxillo-mandibular actinomycosis were investigated; spotty-type bone resorption was observed in 66.7% (8/12). Moreover, FDG-PET/CT showed abnormal accumulation, but FAMT-PET/CT showed no apparent abnormal accumulation. CONCLUSIONS: Clinical and imaging findings of maxillo-mandibular actinomycosis are similar to those of intraosseous carcinoma. Differential diagnostic screening can confirm spotty-type bone resorption in cortical bone with CT and specific accumulation in malignant tumors with FAMT-PET/CT. This screening facilitates the rapid implementation of therapeutic interventions.

α-Emitting cancer therapy using 211 At-AAMT targeting LAT1.

α-Methyl-l-tyrosine (AMT) has a high affinity for the cancer-specific l-type amino acid transporter 1 (LAT1). Therefore, we established an anti-cancer therapy, with 211 At-labeled α-methyl-l-tyrosine (211 At-AAMT) as a carrier of 211 At into tumors. 211 At-AAMT had high affinity for LAT1, inhibited tumor cell growth, and induced DNA double-stranded breaks in vitro. We evaluated the accumulation of 211 At-AAMT in vivo and the role of LAT1. Treatment with 0.4 MBq/mouse 211 At-AAMT inhibited tumor growth in the PANC-1 tumor model and 1 MBq/mouse 211 At-AAMT inhibited metastasis in the lung of the B16F10 metastasis model. Our results suggested that 211 At would be useful for anti-cancer therapy and that LAT1 is suitable as a target for radionuclide therapy.

Cytokine storms caused by novel coronavirus 2019 and treatment for cardiac injury.

Since December 2019, an outbreak of a new coronavirus, COVID-19, infection has been taking place. At present, COVID-19 has spread to most countries worldwide. The latest evidence suggests that cytokine storm syndrome (CSS) is an important cause of the transition from mild to critical pneumonia and critically ill patients' death. The sudden exacerbation of COVID-19 may be related to a cytokine storm. Therefore, early identification and active treatment of CSS may play very important roles in improving the patients' prognosis, and these tasks are given attention in the current treatment of new Coronavirus pneumonia. However, there is still no specific medicine for this purpose. This article reviews cytokine storms and conducts an exploratory review of pharmacotherapy for cytokine storms to provide a reference for clinical treatment.

Preoperative Management of Pheochromocytoma and Paraganglioma.

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors, characterized by excessive release of catecholamines (CAs), and manifested as the classic triad of headaches, palpitations, profuse sweating, and a variety of other signs and symptoms. The diagnosis of PPGL requires both evidence of excessive release of CAs and anatomical localization of CA-secreting tumor. Surgery is the mainstay of treatment for all patients with PPGL unless contraindicated. However, without proper preparation, the release of excessive CAs, especially during surgery, can result in lethal cardiovascular complications. Herein, we briefly reviewed the pathogenesis of this disease, discussed the current approaches and evidence available for preoperative management, summarizing the results of the latest studies which compared the efficacies of preoperative management with or without α adrenergic-receptor antagonists, aiming to facilitate better understanding of the preoperative management of PPGL for the physicians.

Pharmacological depletion of serotonin and norepinephrine with para-chlorophenylalanine and alpha-methyl-p-tyrosine reverses the antidepressant-like effects of adolescent caffeine exposure in the male rat.

Adolescent exposure to caffeine has been shown to decrease immobility in the forced swim test, suggesting and antidepressant-like effect of caffeine; however, studies have produced different results with regard to caffeine-induced active behaviors. The present study attempted to clarify the possible neurochemical mechanisms of caffeine's action by selectively depleting norepinephrine with alpha-methyl-p-tyrosine or serotonin with para-chlorophenylalanine in two separate experiments and assessing the ability for caffeine to alter anxiety-like and depressive-like behavior. Caffeine-treated adolescent male rats were exposed to caffeine (0.25 g/L) in their drinking water beginning on P28. A-methyl-p-tyrosine, para-chlorophenylalanine, or saline were administered prior to light-dark, open field, and forced swim testing beginning on P45. Caffeine-induced reductions in immobility and increases in swimming in the forced swim test were reversed by both a-methyl-p-tyrosine and para-chlorophenylalanine. Caffeine-induced increases in crosses and rears were reversed by para-chlorophenylalanine but not alpha-methyl-p-tyrosine, whereas caffeine-induced increases in transitions in the LD test were reversed by alpha-methyl-p-tyrosine but not para-chlorophenylalanine. Taken together, these results suggest that caffeine-induced decreases in immobility in male rats requires both norepinephrine and serotonin as depletion of either prevents the induction of immobility by chronic caffeine.

Uptake of positron emission tomography tracers reflects the tumor immune status in esophageal squamous cell carcinoma.

The relationship between the local immune status and cancer metabolism regarding 18 F-FDG and 18 F-FAMT uptake in esophageal squamous cell carcinoma (ESCC) remains unknown. The present study examined the correlations between tumor immune status, clinicopathological factors, and positron emission tomography (PET) tracer uptake in ESCC. Forty-one ESCC patients who underwent 18 F-FDG PET and 18 F-FAMT PET before surgery were enrolled in the study. Immunohistochemistry was conducted for programmed death 1 (PD-1), CD8, Ki-67, CD34, GLUT1 (18 F-FDG transporter) and LAT1 (18 F-FAMT transporter). ESCC specimens with high tumoral PD-L1 and high CD8-positive lymphocytes were considered to have "hot tumor immune status." High PD-L1 expression (53.7%) was significantly associated with tumor/lymphatic/venous invasion (P = 0.028, 0.032 and 0.018), stage (P = 0.041), CD8-positive lymphocytes (P < 0.001), GLUT1 (P < 0.001), LAT1 expression (P = 0.006), Ki-67 labelling index (P = 0.009) and CD34-positive vessel counts (P < 0.001). SUVmax of 18 F-FDG was significantly higher in high PD-L1 cases than in low PD-L1 cases (P = 0.009). SUVmax of 18 F-FAMT was significantly higher in high PD-L1 (P < 0.001), high CD8 (P = 0.012) and hot tumor groups (P = 0.028) than in other groups. High SUVmax of 18 F-FAMT (≥4.15) was identified as the only predictor of hot tumor immune status. High PET tracer uptake was significantly associated with cancer aggressiveness and hot tumor immune status in ESCC. PET imaging may be an effective tool to predict tumor immune status in ESCC with respect to immune checkpoint inhibitor sensitivity.

A fluorescence signal amplification strategy for modification-free ratiometric determination of tyrosinase in situ based on the use of dual-templated copper nanoclusters.

A fluorescence resonance energy transfer (FRET)-based in situ fluorescence signal amplification strategy is described for the determination of tyrosinase (TYR). In this assay, a dual-templated copper nanocluster (CuNCs) stabilized by bovine serum albumin (BSA) and glycylglycine (Gly-Gly) was used as an energy donor. Metyrosine was employed as a TYR substrate because its enzyme catalytic product (methyldopa) was able to function as a monomer molecule to form fluorescent polymethyldopa (PMeDP) with the assistance of BSA/Gly-Gly CuNCs. In this process, PMeDP can combine with BSA/Gly-Gly CuNCs without extra modification and then acts as an energy receptor, which leads to a remarkable FRET from BSA/Gly-Gly CuNCs to PMeDP. Interestingly, the fluorescence intensity of PMeDP was strengthened greatly in the FRET-based sensor compared to the separate excitation, which provided good sensitivity for TYR sensing. Illuminated under a UV light source, the fluorescence signal change is observed from dark violet to bright green. Therefore, the present sensing system affords a reliable ratiometric assay for TYR determination. Also, the ratio of fluorescence intensity between PMeDP (λem at 505 nm, F505) and BSA/Gly-Gly CuNCs (λem at 415 nm, F415) was used for quantitative determination of TYR. The sensing system was easily operated in aqueous media with an exciting detection limit of 44.0 U L-1. This sensing strategy has been applied to the screening of inhibitors. Graphical abstract Schematic representation of the strategy for the determination of tyrosinase.

A first-in-human study of the novel metabolism-based anti-cancer agent SM-88 in subjects with advanced metastatic cancer.

Purpose SM-88 (D,L-alpha-metyrosine; racemetyrosine) is a novel anti-cancer agent, used with melanin, phenytoin, and sirolimus (SMK Therapy). This pilot first-in-human study characterized the safety, tolerability, and efficacy of SMK Therapy in subjects with advanced metastatic cancer. Methods All subjects (n = 30) received SMK Therapy for an initial 6 week Cycle (5 days on, 2 off per week) and continued if well tolerated. Safety signals, clinical response, overall survival, progression free survival (PFS), and quality of life changes were assessed. Results The most common drug related adverse events were hyperpigmentation and rash. All drug related adverse events were mild to moderate in intensity. Following treatment with SMK Therapy, 4 subjects achieved complete response, 6 partial response, and 17 stable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 (total clinical benefit 90%). Responses were observed within 6 weeks, and continued to improve, with 3 complete and 3 partial responders achieving best response after at least 3.2 months. Durable stable disease was observed, lasting a median duration of 11 months (range 1-31 months). Median overall survival for all subjects was 29.8 months, and median PFS was 13 months. Following 6 weeks of treatment, most (83.3%) subjects showed an improvement in Eastern Cooperative Oncology Group (ECOG) score and an improvement in the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ 30) global health status (baseline 61.2 ± 25.0; end of Cycle 1 80.7 ± 14.7; n = 29; p < 0.001). Conclusions The results of this study support continued development of SM-88.

Effects of dopamine and serotonin synthesis inhibitors on the ketamine-, d-amphetamine-, and cocaine-induced locomotor activity of preweanling and adolescent rats: sex differences.

The pattern of ketamine-induced locomotor activity varies substantially across ontogeny and according to sex. Although ketamine is classified as an NMDA channel blocker, it appears to stimulate the locomotor activity of both male and female rats via a monoaminergic mechanism. To more precisely determine the neural mechanisms underlying ketamine's actions, male and female preweanling and adolescent rats were pretreated with vehicle, the dopamine (DA) synthesis inhibitor ∝-methyl-DL-p-tyrosine (AMPT), or the serotonin (5-HT) synthesis inhibitor 4-chloro-DL-phenylalanine methyl ester hydrochloride (PCPA). After completion of the pretreatment regimen, the locomotor activating effects of saline, ketamine, d-amphetamine, and cocaine were assessed during a 2 h test session. In addition, the ability of AMPT and PCPA to reduce dorsal striatal DA and 5-HT content was measured in male and female preweanling, adolescent, and adult rats. Results showed that AMPT and PCPA reduced, but did not fully attenuate, the ketamine-induced locomotor activity of preweanling rats and female adolescent rats. Ketamine (20 and 40 mg/kg) caused a minimal amount of locomotor activity in male adolescent rats, and this effect was not significantly modified by AMPT or PCPA pretreatment. When compared to ketamine, d-amphetamine and cocaine produced different patterns of locomotor activity across ontogeny; moreover, AMPT and PCPA pretreatment affected psychostimulant- and ketamine-induced locomotion differently. When these results are considered together, it appears that both dopaminergic and serotonergic mechanisms mediate the ketamine-induced locomotor activity of preweanling and female adolescent rats. The dichotomous actions of ketamine relative to the psychostimulants in vehicle-, AMPT-, and PCPA-treated rats, suggests that ketamine modulates DA and 5-HT neurotransmission through an indirect mechanism.

Relationship Between Tumor Immune Markers and Fluorine-18-α-Methyltyrosine ([18F]FAMT) Uptake in Patients with Lung Cancer.

PURPOSE: 3-[18F]Fluoro-α-methyl-L-tyrosine ([18F]FAMT) is an amino acid positron emission tomography (PET) tracer specific for cancer detection by assessment of tumor amino acid metabolism. Little is known on whether or not the uptake of [18F]FAMT within cancer cells is associated with the expression of programmed death ligand-1 (PD-L1), a predictor of anti-PD-1 antibody efficacy. We conducted a clinicopathological study to assess the expression of PD-L1 and the presence of tumor-infiltrating lymphocytes (TILs) in patients with non-small cell lung cancer (NSCLC) diagnosed by PET. PROCEDURES: A total of 75 patients with NSCLC who underwent [18F]FAMT and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) PET were enrolled in the study. Tumor specimens were stained by immunohistochemistry for glucose transporter 1 (Glut1), PD-L1 (using different antibody clones including E1L3N and 28-8), CD3, CD4, and CD8. The uptake of [18F]FAMT was correlated with clinicopathological variables. RESULTS: High uptake of [18F]FAMT was significantly associated with disease staging, initial treatment (surgical resection or chemotherapy), and the expression of PD-L1 (E1L3N). The value of the maximum standardized uptake value (SUVmax) for [18F]FAMT was significantly correlated with PD-L1 (E1L3N) expression, Glut1, and the SUVmax for [18F]FDG in patients with histological results of adenocarcinoma (AC) and advanced disease. A validation cohort for anti-PD-L1 using clone 28-8 showed a statistically significant correlation between SUVmax for [18F]FAMT and the expression of PD-L1 (28-8) and between the expression of PD-L1 (E1L3N) and PD-L1 (28-8). CONCLUSIONS: The uptake of [18F]FAMT on PET imaging was significantly correlated with PD-L1 expression in NSCLC, especially in patients with AC and advanced disease.

Blockade of the dopaminergic neurotransmission with AMPT and reserpine induces a differential expression of genes of the dopaminergic phenotype in substantia nigra.

Dopaminergic neurons have the ability to release Dopamine from their axons as well as from their soma and dendrites. This somatodendritically-released Dopamine induces an autoinhibition of Dopaminergic neurons mediated by D2 autoreceptors, and the stimulation of neighbor GABAergic neurons mediated by D1 receptors (D1r). Here, our results suggest that the somatodendritic release of Dopamine in the substantia nigra (SN) may stimulate GABAergic neurons that project their axons into the hippocampus. Using semiquantitative multiplex RT-PCR we show that chronic blockade of the Dopaminergic neurotransmission with both AMPT and reserpine specifically decreases the expression levels of D1r, remarkably this may be the result of an antagonistic effect between AMPT and reserpine, as they induced the expression of a different set of genes when treated by separate. Furthermore, using anterograde and retrograde tracing techniques, we found that the GABAergic neurons that express D1r also project their axons in to the CA1 region of the hippocampus. Finally, we also found that the same treatment that decreases the expression levels of D1r in SN, also induces an impairment in the performance in an appetitive learning task that requires the coding of reward as well as navigational skills. Overall, our findings show the presence of a GABAergic interconnection between the SNr and the hippocampus mediated by D1r.

Correlation between urinary fractionated metanephrines in 24-hour and spot urine samples for evaluating the therapeutic effect of metyrosine: a subanalysis of a multicenter, open-label phase I/II study.

We recently conducted an open-label phase I/II study to evaluate the efficacy and safety of preoperative and chronic treatment with metyrosine (an inhibitor of catecholamine synthesis) in pheochromocytoma/paraganglioma (PPGL) in Japan. We compared creatinine-corrected metanephrine fractions in spot urine and 24-hour urine samples (the current standard for the screening and diagnosis of PPGLs) from 16 patients to assess the therapeutic effect of metyrosine. Percent changes from baseline in urinary metanephrine (uMN) or normetanephrine (uNMN) were compared between spot and 24-hour urine samples. Mean percent changes in uMN or uNMN in spot and 24-hour urine were -26.36% and -29.27%, respectively. The difference in the percent change from baseline between uMN or uNMN in spot and 24-hour urine was small (-2.90%). The correlation coefficient was 0.87 for percent changes from baseline between uMN or uNMN measured in spot and 24-hour urine. The area under the receiver operator characteristic (ROC) curve of uMN or uNMN measured in spot urine vs. 24-hour urine (reference standard) to assess the efficacy of metyrosine treatment was 0.93. Correlations and ROCs between 24-hour urinary vanillylmandelic acid, adrenaline, and noradrenaline and 24-hour uMN or uNMN were similar to those between spot uMN or uNMN and 24-hour uMN or uNMN. No large difference was observed between spot and 24-hour urine for the assessment of metyrosine treatment by quantifying uMN or uNMN in Japanese patients with PPGLs. These results suggest that spot urine samples may be useful in assessing the therapeutic effect of metyrosine.