Effects of dietary omega-3 intake on vigilant attention and resting-state functional connectivity in neurotypical children and adolescents.

BACKGROUND: Vigilant Attention (VA) is a critical cognitive function allowing to maintain our attention, particularly in redundant or intellectually unchallenging situations. Evidence has shown that, as the brain develops, VA abilities rapidly improve throughout childhood and adolescence. Dietary omega-3 polyunsaturated fats (PUFA), playing a critical role for proper brain development and maturation of cortical regions, may contribute to variations in VA abilities. OBJECTIVE: The present study investigated the effect of dietary omega-3 PUFA intake (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)) on resting-state functional connectivity (rsFC) of a meta-analytically defined VA network in 24 neurotypical children and adolescents (7.3-17.2 years) from the Healthy Brain Network databank. METHODS: Functional MRI and phenotypical information were collected from the Healthy Brain Network databank. Intake of omega-3 DHA and EPA was assessed using a food frequency questionnaire and was adjusted for total calorie intake. Out of scanner VA-related performance was assessed using the VA condition of the Adaptive Cognitive Evaluation tool. RESULTS: Overall, reported intake of omega-3 PUFA was not significantly associated with VA-related performance. Furthermore, energy-adjusted omega-3 intake was not significantly correlated with rsFC within the VA network. A complementary whole-brain analysis revealed that energy-adjusted omega-3 intake was correlated with decreased rsFC between parieto-occipital brain regions. CONCLUSION: The present study was not able to detect a relationship between dietary omega-3 and rsFC or VA performance.

Age-related resting-state functional connectivity of the Vigilant Attention network in children and adolescents.

The development of Vigilant Attention (VA), the ability to focus and maintain our attention to repetitive and cognitively unchallenging tasks over time, has been investigated for more than a decade. The development of this critical executive function across the lifespan has been characterised by a rapid improvement in VA performance throughout childhood and adolescence, a steady improvement in adulthood and a slow decline in older adulthood. However, the development of the neural correlates of VA in children and adolescents remains poorly understood. Using a cross-sectional design, the present study used a meta-analytically defined VA network in children and adolescents to explore the developmental trend of the resting-state functional connectivity (rsFC) within the VA network across two independent cohorts. The results showed a linear and non-linear decrease of rsFC between the left and right VA brain regions across age. However, the results could not be reproduced in the replication cohort, potentially due to a smaller sample size. Based on previous findings from behavioural studies, the present findings suggest that changes in rsFC may underlie a developmental shift in cognitive strategies in neurotypical children and adolescents.

Functional connectivity of the vigilant-attention network in children and adolescents with attention-deficit/hyperactivity disorder.

The ability to maintain attention to simple tasks (i.e., vigilant attention, VA) is often impaired in attention-deficit/hyperactivity disorder (ADHD), but the underlying pathophysiological mechanisms at the brain network level are not clear yet. We therefore investigated ADHD-related differences in resting-state functional connectivity within a meta-analytically defined brain network of 14 distinct regions subserving VA (comprising 91 connections in total), as well as the association of connectivity with markers of behavioural dysfunction in 17 children (age range: 9-14 years) with a diagnosis of ADHD and 21 age-matched neurotypical controls. Our analyses revealed selective, rather than global, differences in the intrinsic coupling between nodes of the VA-related brain network in children with ADHD, relative to controls. In particular, ADHD patients showed substantially diminished intrinsic coupling for 7 connections and increased coupling for 4 connections, with many differences involving connectivity with the anterior insula. Moreover, connectivity strength of several aberrant connections was found to be associated with core aspects of ADHD symptomatology, such as poor attention, difficulties with social functioning, and impaired cognitive control, attesting to the behavioural relevance of specific connectivity differences observed in the resting state.

Robotic surgery: new robots and finally some real competition!

PURPOSE: For the last 20 years, the predominant robot used in laparoscopic surgery has been Da Vinci by Intuitive Surgical. This monopoly situation has led to rising costs and relatively slow innovation. This article aims to discuss the two new robotic devices for laparoscopic surgery which have received regulatory approval for human use in different parts of the world. MATERIALS: A short description of the Senhance Surgical Robotic System and the REVO-I Robot Platform and their pros and cons compared to the Da Vinci system is presented. A discussion about the differences between the three robotic systems now in the market is presented, as well as a short review of the present state of robotic assistance in surgery and where we are headed.

Understanding the Atmospheric Oxidation of HFE-7500 (C3F7CF(OC2H5)CF(CF3)2) Initiated by Cl Atom and NO3 Radical from Theory.

Kinetics and mechanistic pathways for atmospheric oxidation of HFE-7500 ( n-C3F7CF(OCH2CH3)CF(CF3)2) initiated by Cl atom and NO3 radical have been studied using density functional theory. Oxidative degradation pathways facilitated by H-abstraction from the -OCH2 or -CH3 groups in HFE-7500 have been considered. It has been shown that H-abstraction from the α-site (-OCH2) is favored over other reaction pathways. The rate constants were computed employing transition-state theory and canonical variation transition-state theory incorporating small curvature tunnelling correction, over the temperature range of 250-450 K at atmospheric pressure. Calculated rate constants at 298 K and 1 atm compare well with earlier experiments. Temperature dependence of the rate constants and branching ratios for these pathways contributing to overall reaction are described. It has been shown that the rate constants over the studied temperature range was found to fit well to the modified Arrhenius equation (in cm3 molecule-1 s-1) kCl = 1.10 × 10-14  T0.04 exp(-69.87 ± 1.41/T) and kNO3 = 7.66 × 10-26 T3.30 exp(596.40 ± 1.22/T). Standard enthalpies of formation for the reactant (C3F7CF(OCH2CH3)CF(CF3)2) and the products [C3F7CF(OC•HCH3)CF(CF3)2 and C3F7CF(OCH2C•H2)CF(CF3)2] during H-abstraction are derived using the isodesmic approach. Atmospheric implications of the titled molecule are presented.

Kinetics and Mechanistic Investigations of Atmospheric Oxidation of HFO-1345fz by OH Radical: Insights from Theory.

HFO-1345fz (CF3CF2CH═CH2 or 3,3,4,4,4-pentafluoro-1-butene) belongs to a class of hydrofluoro-olefins and represents a new generation of potential foam expansion agents. Its atmospheric impact and environmental acceptability can be estimated from the studies of kinetics and mechanism of its oxidative degradation. The molecular insights accompanying the reaction pathways in terms of the characterization of intermediates or products and radiative properties should prove useful for large-scale industrial applications. Systematic mechanistic gas-phase kinetics investigations on the reactivity of HFO-1345fz with the •OH facilitating a variety of degradation routes have been carried out employing the M06-2x-based density functional theory. Structure and energetics of different reaction pathways such as hydrogen abstraction, •OH addition, isomerization-dissociation, or interaction with atmospheric O2 have been analyzed. The formation of gaseous products from the interaction of HFO-1345fz with •OH in the absence and presence of NOx atmospheric conditions has been reported. Calculated branching ratios have shown that the addition channel dominates such oxidative degradation, whereas the abstraction channel contributes negligibly to the global rate constant and addition of •OH to the terminal carbon is favored over the nonterminal one. The rate constants for all reaction channels were computed by conventional transition state theory (TST) and canonical variation transition state theory (CVT) including small curvature tunneling (SCT) over the temperature range of 200-1000 K at atmospheric pressure. The CVT calculated rate constant for the reaction at 298 K was shown to be 1.17 × 10-12 cm3 molecule-1 s-1, which compares well with the 1.24 × 10-12 cm3 molecule-1 s-1 as obtained from TST and is in excellent agreement with the experiments reported earlier. The atmospheric lifetime, radiative efficiency, and global warming potential (GWP) have also been obtained.

Brain iron concentration in childhood ADHD: A systematic review of neuroimaging studies.

Iron deficiency may play a role in the pathophysiology of Attention Deficit/Hyperactivity Disorder (ADHD). Due to its preponderant function in monoamine catecholamine and myelin synthesis, brain iron concentration may be of primary interest in the investigation of iron dysregulation in ADHD. This study reviewed current evidence of brain iron abnormalities in children and adolescents with ADHD using magnetic resonance imaging methods, such as relaxometry and quantitative susceptibility mapping, to assess brain iron estimates. The study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search was performed for studies published between January 1, 2008 and July 7, 2023 in Medline, Scopus and Proquest. Regions of interest, brain iron index values and phenotypical information were extracted from the relevant studies. Risk of bias was assessed using a modified version of the National Heart, Lung, and Blood Institute quality assessment tool. Seven cross-sectional studies comparing brain iron estimates in children with ADHD with neurotypical children were included. Significantly reduced brain iron content in medication-naïve children with ADHD was a consistent finding. Two studies found psychostimulant use may increase and normalize brain iron concentration in children with ADHD. The findings were consistent across the studies despite differing methodologies and may lay the early foundation for the recognition of a potential biomarker in ADHD, although longitudinal prospective neuroimaging studies using larger sample sizes are required. Lastly, the effects of iron supplementation on brain iron concentration in children with ADHD need to be elucidated.

Atypical Antipsychotic Prescribing in Australian Children and Adolescents: A Survey of Medical Practitioners.

OBJECTIVE: Prescriptions for atypical antipsychotics in children and adolescents are increasing globally. However, a precise understanding of the clinical variables and evidence that prescribers consider before using these agents is lacking. While empirical literature on the long-term safety and efficacy of these medications is available, the literature concerning their use in these younger age groups is relatively sparse. In this study, we examined the current prescribing patterns of medical professionals employed by a public health service in Australia. METHODS: A survey examining their current practice when prescribing atypical antipsychotics to children and adolescents was completed by 103 physicians. Questions were asked about commonly prescribed atypical antipsychotics, indications, dose ranges, target symptoms, duration of treatment, and the evidence base(s) used when making treatment decisions. RESULTS: Physicians prescribed atypical antipsychotics for a wide range of indications in this age group, with the most common agents being risperidone, quetiapine, and olanzapine. Adverse effects were reported as the main reason for treatment discontinuation. More than half of the respondents indicated that the most common source of guidance/evidence they referred to when initiating prescriptions were peers or expert opinion. CONCLUSIONS: Children and adolescents were prescribed a number of atypical antipsychotics for a variety of indications, with variable perceived confidence and a relatively heavy reliance on "own or peer experience" as opposed to good quality evidence. Challenges exist for both prescribers and policymakers, and further "head-to-head" studies are needed in this age group to ensure that a balance is maintained between therapeutic benefit and safety.

Implication of saturated fats in the aetiology of childhood attention deficit/hyperactivity disorder - A narrative review.

Attention Deficit/Hyperactivity Disorder (ADHD) is the most common mental health disorder in the paediatric population. ADHD is highly comorbid with obesity, and has also been associated with poor dietary patterns such as increased consumption of refined carbohydrates and saturated fats. Although ADHD in children was associated with high consumption of saturated fats, so far there has been no evidence-based attempt to integrate dietary strategies controlling for intake of saturated fats into the etiological framework of the disorder. Evidence from human studies and animal models has shown that diets high in saturated fats are detrimental for the development of dopaminergic neurocircuitries, synthesis of neurofactors (e.g. brain derived neurotrophic factor) and may promote brain inflammatory processes. Notably, animal models provide evidence that early life consumption of a high saturated fats diet may impair the development of central dopamine pathways. In the present paper, we review the impact of high saturated fats diets on neurobiological processes in human studies and animal models, and how these associations may be relevant to the neuropathophysiology of ADHD in children. The validation of this relationship and its underlying mechanisms through future investigative studies could have implications for the prevention or exacerbation of ADHD symptoms, improve the understanding of the pathogenesis of the disorder, and help design future dietary studies in patients with ADHD.

Lurasidone for Adolescents With Complex Mental Disorders: A Case Series.

OBJECTIVES: Lurasidone is a new second generation (atypical) antipsychotic agent with unique receptor affinity and side-effect profiles, but limited literature is available on its use in adolescent populations. Contrasting with research treatment trials which typically recruit patients by stringent selection criteria, this case series examined the effects and tolerability of using lurasidone in adolescents within real-life clinical settings in treating complex cases who had not responded to other therapy options. METHODS: We conducted a retrospective case-note audit of 6 adolescents aged 14 to 17 years old attending community child and adolescent mental health services (CAMHS) who were prescribed lurasidone. RESULTS: Lurasidone had been prescribed for a range of "hard-to-manage" conditions with complex comorbidities, in adolescents in relation to specific use of lurasidone on the basis of clinical and pharmacological indications after exhausting more conventional treatment options. Case-note review suggested response to lurasidone was clinically positive in 3 cases, equivocal/marginal in 2 cases, and ineffective in 1 case. There were no cases of poor tolerance or adverse effects. Notably, positive responses for depressive and irritable mood symptoms were specifically recorded by prescribing clinicians, indicative of benefits on symptom improvement. No lurasidone attributed weight gain, galactorrhoea, metabolic abnormalities, sexual dysfunction or intolerance were reported. Pro-cognitive effects were not detected; but our findings were constrained by the non-systematic and incomplete information ascertainment, typical in retrospective case-note review. CONCLUSION: This case series provides preliminary data supporting lurasidone's potential use in adolescents of complex clinical needs (but without a clinical diagnosis of bipolar disorder) within real-life clinical settings. Lurasidone appears to show a weight-sparing effect, in addition to improving mood symptoms in some cases. Lurasidone deserves further study for its use in the adolescent population (outside the remit of FDA) given its potential more favorable risk-benefit profile in young people. The favorable tolerability appear to be borne out by the pharmacodynamic predictions in our complex patients who would be excluded in formal clinical trial studies.

The use of a novel reverse thermosensitive polymer to prevent ureteral stone retropulsion during intracorporeal lithotripsy: a randomized, controlled trial.

PURPOSE: We present the first randomized clinical study using BackStop, a novel reverse thermosensitive water-soluble polymer that is dispensed above the stone(s) and temporarily occludes the ureter to prevent retropulsion of stone fragments during ureteroscopic lithotripsy. After fragmentation is completed and concretions are extracted, conventional irrigation with saline dissolves the polymer, which is then flushed out. MATERIALS AND METHODS: A total of 68 subjects with a single stone in the proximal ureter and an indication for ureteroscopic lithotripsy were enrolled in this prospective, randomized, single-blind, controlled, multisite clinical study. Each subject was randomly assigned to the BackStop group (34) or the control group (34 with no antiretropulsion device). For subjects in the experimental group BackStop was dispensed into the ureter above the stone using a 3Fr or 5Fr catheter. Ureteroscopic lithotripsy was performed in all subjects using pneumatic or laser energy. Measured end points included the retropulsion rate, the need for subsequent procedures, the stone-free rate at followup, the occurrence of adverse events and ureteral occlusion, if any, and post-stone fragmentation and extraction. RESULTS: Subjects randomized to the BackStop group experienced a statistically significant (p = 0.0002) lower rate of retropulsion (8.8%, 3 of 34) vs the control group (52.9%, 18/34). There were no adverse events in the BackStop group and BackStop was successfully dissolved in every subject, resulting in a patent ureter. CONCLUSIONS: BackStop appears to be a novel, safe and effective means of preventing stone fragment retropulsion during ureteroscopic lithotripsy for the management of ureteral stones.

Meta-analysis of the neural correlates of vigilant attention in children and adolescents.

Vigilant Attention (VA), defined as the ability to maintain attention to cognitively unchallenging activities over a prolonged period of time, is critical to support higher cognitive functions and many behaviours in our everyday life. Evidence has shown that VA rapidly improves throughout childhood and adolescence until young adulthood and tends to decline in older adulthood. Although neuroimaging studies have extensively investigated this cognitive function in adults, the neural correlates of VA in neurotypical children and adolescents remain unclear. The current meta-analysis reviewed and examined functional neuroimaging studies in paediatric populations that used behavioural tasks involving VA. The selected studies (N = 25) were analyzed using the activation likelihood estimation method. Findings showed convergence of activation in mainly right-lateralized brain areas, including dorsomedial frontal cortex and parieto-temporal areas, and are consistent with previous literature on the neural correlates of VA. Results are discussed in terms of their functional and developmental implications for VA in children and adolescents.

Laparoendoscopic single site surgery in urology.

Laparoendoscopic single site (LESS) surgery is a recently coined term that refers to a group of techniques that perform laparoscopic intervention through a single abdominal incision often hidden within the umbilicus. The relative ease and swiftness of early success of LESS surgery is in large part because of the familiarity of current practitioners with advanced laparoscopic techniques and the advent of several technologic advances in the areas of instrumentation, camera systems, and access devices. As ongoing advancements in instrumentation and future robotics platforms are incorporated, the scope and application of LESS surgery is likely to expand. Ultimately, prospective studies that compare the safety and effectiveness of this new approach with the standard conventional laparoscopic approach will determine the future role in surgical practice.

Intensive community treatment and support "Youth Wraparound" service in Western Australia: A case and feasibility study.

BACKGROUND: Multiple services are often needed to address the needs of young people with complex emotional or behavioural needs. The Youth Wraparound model of service aims to provide all health and supportive services from one coordinating agency. While this has been researched overseas, there are currently few examples of this described in the Australian psychiatric context. AIM: To document the implementation and evaluation of a Youth Wraparound service which was provided to a young person with exceptionally complex and challenging needs for 6 months. A single-case study design is presented with an evaluation of the clinical outcome and economic costs. METHODS: We present a description of the service context, principles of the model of care, implementation process, and an evaluation of service utilization data from health and child protection services and mental health records. A single-case longitudinal design compared service utilization data obtained up to 3 years prior to treatment with data collected one and a half years since treatment commenced. RESULTS: There were significant reductions in the number of admissions to emergency departments, mental health wards and secure units, and improvements in mental health and well-being. Yearly average time in institutional settings reduced from 69% to 7%. Cost savings in health utilization were estimated at $2 326 790. CONCLUSIONS: The Youth Wraparound model has the potential to offer improved clinical outcomes, significant cost savings over time, improved coordination between care providers, and an alternative to detention or incarceration.

Acute Tryptophan Depletion Moja-De: A Method to Study Central Nervous Serotonin Function in Children and Adolescents.

Serotonin (5-HT) is widely implicated as a key neurotransmitter relevant to a range of psychiatric disorders and psychological processes. The role of central nervous 5-HT function underlying these processes can be examined through serotonergic challenge methodologies. Acute tryptophan depletion (ATD) is a key challenge method whereby a diminished dietary intake of tryptophan-the amino acid precursor to brain 5-HT synthesis-results in temporary diminished central nervous 5-HT synthesis. While this particular methodology has been used in adult populations, it was only recently that modifications were made to enable the use of ATD in child and adolescent populations. Additionally, the Moja-De modification of the ATD challenge methodology has demonstrated benefits over other ATD techniques used previously. The aim of this protocol paper is to describe the ATD Moja-De methodology in detail, its benefits, as well as studies that have been conducted to validate the procedure in child and adolescent samples. The ATD Moja-De protocol provides a potential methodology for investigating the role of central nervous 5-HT via manipulation of brain tryptophan availability in human psychopathology from a developmental viewpoint.

No detectable effects of acute tryptophan depletion on short-term immune system cytokine levels in healthy adults.

Objectives: Recent research suggested an influence of diminished central nervous serotonin (5-HT) synthesis on the leptin axis via immunological mechanisms in healthy adult females. However, studies assessing immunological parameters in combination with dietary challenge techniques that impact brain 5-HT synthesis in humans are lacking. Methods: In the present trial, a pilot analysis was conducted on data obtained in healthy adult humans receiving either different dietary acute tryptophan depletion (ATD) challenge or tryptophan (TRP)-balanced control conditions (BAL) to study the effects of reduced central nervous 5-HT synthesis on serum tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß) and IL-6 concentrations. The data of N = 35 healthy adults were analysed who were randomly subjected to one of the following two dietary conditions in a double-blind between-subject approach: (1) The Moja-De ATD challenge (ATD), or (2) TRP-balanced control condition for ATD Moja-De (BAL). Serum concentrations for the assessment of relevant parameters (TNF-α, IL-1ß and IL-6) and relevant TRP-related characteristics after the respective challenge procedures were assessed at baseline (T0) and in hourly intervals after administration over a period of 6 h (T1-T6). Results: The ATD condition did not result in significant changes to cytokine concentrations for the entire study sample, or in male and female subgroups. Depletion of CNS 5-HT via dietary TRP depletion appears to have no statistically significant short-term impact on cytokine concentrations in healthy adults. Conclusions: Future research on immunological stressors in combination with challenge techniques will be of value in order to further disentangle the complex interplay between brain 5-HT synthesis and immunological pathways.

Single-incision laparoscopic surgery: initial urological experience and comparison with natural-orifice transluminal endoscopic surgery.

Laparoscopic approaches have increasingly assumed a central role in the management of benign and malignant surgical diseases. While laparoscopy is less morbid than open surgery, it still requires several incisions, each > or =1-2 cm long. Each incision risks morbidity from bleeding, hernia and/or internal organ damage, and incrementally decreases cosmesis. An alternative to conventional laparoscopy is single-incision laparoscopic surgery (SILS), in which articulating or bent instrumentation with specialized multi-lumen ports is used. These technical innovations obviate the need to externally space trocars for triangulation, thus allowing the creation of a small, solitary portal of entry into the abdomen. Laboratory and early clinical series showed the feasibility as well as safe and successful completion of SILS. Natural-orifice transluminal endoscopic surgery (NOTES) is another exciting development in minimally invasive urology, but existing flexible endoscopes and instruments are limited in providing a platform for this form of advanced surgery, resulting in the slow adoption of NOTES. Future work is needed to improve existing instrumentation, increase clinical experience, assess the benefits of both surgical approaches, and explore other potential applications for these novel techniques.

Scarless single port transumbilical nephrectomy and pyeloplasty: first clinical report.

OBJECTIVE: To report the initial clinical cases of scarless, single port, transumbilical nephrectomy and pyeloplasty. PATIENTS AND METHODS: One patient each underwent single port transumbilical nephrectomy and pyeloplasty using the R-Port (Advanced Surgical Concepts), inserted through a transumbilical incision in both cases. Novel, specialized instruments, curved at the shaft, were used in addition to standard laparoscopic instrumentation. During pyeloplasty, a 2-mm needle-port (MiniSite, USSC, Norfolk, CT, USA) was also inserted, with no skin incision, to facilitate suturing. RESULTS: Both procedures were technically successful with no extra-umbilical skin incisions. The total operative duration was 3.4 and 2.7 h, the estimated blood loss 100 and 50 mL, and the hospital stay was 1 and 2 days for the nephrectomy and pyeloplasty, respectively. There were no complications during or after surgery. The total analgesia requirement was 100 and 150 mg of keterolac, and visual analogue pain scores were 8/10 and 2/10 at 1 and 2 days after surgery, respectively. CONCLUSIONS: Transumbilical, single port nephrectomy and pyeloplasty are technically feasible. The first initial clinical experience of organ-ablative and reconstructive renal surgery with this approach is reported.

Using acute tryptophan depletion to investigate predictors of treatment response in adolescents with major depressive disorder: study protocol for a randomised controlled trial.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) are amongst the most prescribed antidepressants for adolescents with depressive symptoms and major depressive disorder. However, SSRIs have significant shortcomings as a first-line treatment considering that not all patients respond to these antidepressants. Amongst paediatric populations, meta-analyses indicate that up to approximately 40% of patients do not respond, and for those who do show benefit, there is substantial heterogeneity in response onset. The neurotransmitter serotonin (5-HT) plays a role in the clinical effectiveness and mechanisms of action of SSRIs. However, the exact and complete mechanism of action and reasons for the low response rate to SSRIs in some adolescent populations remains unknown. METHODS: To examine SSRI response and the role of 5-HT, this study will employ a randomised double-blind within subject, repeated measures design, recruiting adolescent patients with major depressive disorder. Participants will be subjected to acute tryptophan depletion (ATD) and the balanced control condition on two separate study days within a first study phase (Phase A), and the order in which these conditions (ATD/balanced control condition) occur will be random. This phase will be followed by Phase B, where participants will receive open label pharmacological treatment as usual with the SSRI fluoxetine and followed-up over a 12-week period. DISCUSSION: ATD is a neurodietary method typically used to investigate the impact of lowered brain 5-HT synthesis on mood and behaviour. The major hypothesis of this study is that ATD will be negatively associated with mood and cognitive functioning, therefore reflecting individual serotonergic sensitivity and related depressive symptoms. Additionally, we expect the aforementioned effects of ATD administration on mood to predict clinical improvement with regard to overall depressive symptomatology 12 weeks into SSRI treatment. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry (ANZCTR) ACTRN12616001561471 . Registered on 11 November 2016.

Effects of Dietary Acute Tryptophan Depletion (ATD) on NPY Serum Levels in Healthy Adult Humans Whilst Controlling for Methionine Supply-A Pilot Study.

Central nervous serotonin (5-HT) can influence behaviour and neuropsychiatric disorders. Evidence from animal models suggest that lowered levels of neuropeptide Y (NPY) may have similar effects, although it is currently unknown whether decreased central nervous 5-HT impact NPY concentrations. Given that the production of NPY is dependent on the essential amino acid methionine (MET), it is imperative to account for the presence of MET in such investigations. Hence, this study sought to examine the effects of acute tryptophan depletion (ATD; a dietary procedure that temporarily lowers central nervous 5-HT synthesis) on serum concentrations of NPY, whilst using the potential renal acid load indicator (PRAL) to control for levels of MET. In a double-blind repeated measures design, 24 adult humans randomly received an AA-load lacking in TRP (ATD) on one occasion, and a balanced control mixture with TRP (BAL) on a second occasion, both with a PRAL of nearly 47.3 mEq of MET. Blood samples were obtained at 90, 180, and 240 min after each of the AA challenges. ATD, and therefore, diminished substrate availability for brain 5-HT synthesis did not lead to significant changes in serum NPY concentrations over time, compared to BAL, under an acute acidotic stimulus.