Negative feedback control of hypothalamic feeding circuits by the taste of food.

The rewarding taste of food is critical for motivating animals to eat, but whether taste has a parallel function in promoting meal termination is not well understood. Here, we show that hunger-promoting agouti-related peptide (AgRP) neurons are rapidly inhibited during each bout of ingestion by a signal linked to the taste of food. Blocking these transient dips in activity via closed-loop optogenetic stimulation increases food intake by selectively delaying the onset of satiety. We show that upstream leptin-receptor-expressing neurons in the dorsomedial hypothalamus (DMHLepR) are tuned to respond to sweet or fatty tastes and exhibit time-locked activation during feeding that is the mirror image of downstream AgRP cells. These findings reveal an unexpected role for taste in the negative feedback control of ingestion. They also reveal a mechanism by which AgRP neurons, which are the primary cells that drive hunger, are able to influence the moment-by-moment dynamics of food consumption.

Negative feedback control of hunger circuits by the taste of food.

The rewarding taste of food is critical for motivating animals to eat, but whether taste has a parallel function in promoting meal termination is not well understood. Here we show that hunger-promoting AgRP neurons are rapidly inhibited during each bout of ingestion by a signal linked to the taste of food. Blocking these transient dips in activity via closed-loop optogenetic stimulation increases food intake by selectively delaying the onset of satiety. We show that upstream leptin receptor-expressing neurons in the dorsomedial hypothalamus (DMHLepR) are tuned to respond to sweet or fatty tastes and exhibit time-locked activation during feeding that is the mirror image of downstream AgRP cells. These findings reveal an unexpected role for taste in the negative feedback control of ingestion. They also reveal a mechanism by which AgRP neurons, which are the primary cells that drive hunger, are able to influence the moment-by-moment dynamics of food consumption.

Dopamine subsystems that track internal states.

Food and water are rewarding in part because they satisfy our internal needs1,2. Dopaminergic neurons in the ventral tegmental area (VTA) are activated by gustatory rewards3-5, but how animals learn to associate these oral cues with the delayed physiological effects of ingestion is unknown. Here we show that individual dopaminergic neurons in the VTA respond to detection of nutrients or water at specific stages of ingestion. A major subset of dopaminergic neurons tracks changes in systemic hydration that occur tens of minutes after thirsty mice drink water, whereas different dopaminergic neurons respond to nutrients in the gastrointestinal tract. We show that information about fluid balance is transmitted to the VTA by a hypothalamic pathway and then re-routed to downstream circuits that track the oral, gastrointestinal and post-absorptive stages of ingestion. To investigate the function of these signals, we used a paradigm in which a fluid's oral and post-absorptive effects can be independently manipulated and temporally separated. We show that mice rapidly learn to prefer one fluid over another based solely on its rehydrating ability and that this post-ingestive learning is prevented if dopaminergic neurons in the VTA are selectively silenced after consumption. These findings reveal that the midbrain dopamine system contains subsystems that track different modalities and stages of ingestion, on timescales from seconds to tens of minutes, and that this information is used to drive learning about the consequences of ingestion.

Quality of recovery after total hip and knee arthroplasty in South Africa: a national prospective observational cohort study.

BACKGROUND: Encouraged by the widespread adoption of enhanced recovery protocols (ERPs) for elective total hip and knee arthroplasty (THA/TKA) in high-income countries, our nationwide multidisciplinary research group first performed a Delphi study to establish the framework for a unified ERP for THA/TKA in South Africa. The objectives of this second phase of changing practice were to document quality of patient recovery, record patient characteristics and audit standard perioperative practice. METHODS: From May to December 2018, nine South African public hospitals conducted a 10-week prospective observational study of patients undergoing THA/TKA. The primary outcome was 'days alive and at home up to 30 days after surgery' (DAH30) as a patient-centred measure of quality of recovery incorporating early death, hospital length of stay (LOS), discharge destination and readmission during the first 30 days after surgery. Preoperative patient characteristics and perioperative care were documented to audit practice. RESULTS: Twenty-one (10.1%) out of 207 enrolled patients had their surgery cancelled or postponed resulting in 186 study patients. No fatalities were recorded, median LOS was 4 (inter-quartile-range (IQR), 3-5) days and 30-day readmission rate was 3.8%, leading to a median DAH30 of 26 (25-27) days. Forty patients (21.5%) had pre-existing anaemia and 24 (12.9%) were morbidly obese. In the preoperative period, standard care involved assessment in an optimisation clinic, multidisciplinary education and full-body antiseptic wash for 67 (36.2%), 74 (40.0%) and 55 (30.1%) patients, respectively. On the first postoperative day, out-of-bed mobilisation was achieved by 69 (38.1%) patients while multimodal analgesic regimens (paracetamol and Non-Steroid-Anti-Inflammatory-Drugs) were administered to 29 patients (16.0%). CONCLUSION: Quality of recovery measured by a median DAH30 of 26 days justifies performance of THA/TKA in South African public hospitals. That said, perioperative practice, including optimisation of modifiable risk factors, lacked standardisation suggesting that quality of patient care and postoperative recovery may improve with implementation of ERP principles. Notwithstanding the limited resources available, we anticipate that a change of practice for THA/TKA is feasible if 'buy-in' from the involved multidisciplinary units is obtained in the next phase of our nationwide ERP initiative. TRIAL REGISTRATION: The study was registered with ClinicalTrials.gov ( NCT03540667 ).

Genetic Identification of Vagal Sensory Neurons That Control Feeding.

Energy homeostasis requires precise measurement of the quantity and quality of ingested food. The vagus nerve innervates the gut and can detect diverse interoceptive cues, but the identity of the key sensory neurons and corresponding signals that regulate food intake remains unknown. Here, we use an approach for target-specific, single-cell RNA sequencing to generate a map of the vagal cell types that innervate the gastrointestinal tract. We show that unique molecular markers identify vagal neurons with distinct innervation patterns, sensory endings, and function. Surprisingly, we find that food intake is most sensitive to stimulation of mechanoreceptors in the intestine, whereas nutrient-activated mucosal afferents have no effect. Peripheral manipulations combined with central recordings reveal that intestinal mechanoreceptors, but not other cell types, potently and durably inhibit hunger-promoting AgRP neurons in the hypothalamus. These findings identify a key role for intestinal mechanoreceptors in the regulation of feeding.

Kinesin Khc-73/KIF13B modulates retrograde BMP signaling by influencing endosomal dynamics at the Drosophila neuromuscular junction.

Retrograde signaling is essential for neuronal growth, function and survival; however, we know little about how signaling endosomes might be directed from synaptic terminals onto retrograde axonal pathways. We have identified Khc-73, a plus-end directed microtubule motor protein, as a regulator of sorting of endosomes in Drosophila larval motor neurons. The number of synaptic boutons and the amount of neurotransmitter release at the Khc-73 mutant larval neuromuscular junction (NMJ) are normal, but we find a significant decrease in the number of presynaptic release sites. This defect in Khc-73 mutant larvae can be genetically enhanced by a partial genetic loss of Bone Morphogenic Protein (BMP) signaling or suppressed by activation of BMP signaling in motoneurons. Consistently, activation of BMP signaling that normally enhances the accumulation of phosphorylated form of BMP transcription factor Mad in the nuclei, can be suppressed by genetic removal of Khc-73. Using a number of assays including live imaging in larval motor neurons, we show that loss of Khc-73 curbs the ability of retrograde-bound endosomes to leave the synaptic area and join the retrograde axonal pathway. Our findings identify Khc-73 as a regulator of endosomal traffic at the synapse and modulator of retrograde BMP signaling in motoneurons.

Acute Fasting Regulates Retrograde Synaptic Enhancement through a 4E-BP-Dependent Mechanism.

While beneficial effects of fasting on organismal function and health are well appreciated, we know little about the molecular details of how fasting influences synaptic function and plasticity. Our genetic and electrophysiological experiments demonstrate that acute fasting blocks retrograde synaptic enhancement that is normally triggered as a result of reduction in postsynaptic receptor function at the Drosophila larval neuromuscular junction (NMJ). This negative regulation critically depends on transcriptional enhancement of eukaryotic initiation factor 4E binding protein (4E-BP) under the control of the transcription factor Forkhead box O (Foxo). Furthermore, our findings indicate that postsynaptic 4E-BP exerts a constitutive negative input, which is counteracted by a positive regulatory input from the Target of Rapamycin (TOR). This combinatorial retrograde signaling plays a key role in regulating synaptic strength. Our results provide a mechanistic insight into how cellular stress and nutritional scarcity could acutely influence synaptic homeostasis and functional stability in neural circuits.

LRRK2 regulates retrograde synaptic compensation at the Drosophila neuromuscular junction.

Parkinson's disease gene leucine-rich repeat kinase 2 (LRRK2) has been implicated in a number of processes including the regulation of mitochondrial function, autophagy and endocytic dynamics; nevertheless, we know little about its potential role in the regulation of synaptic plasticity. Here we demonstrate that postsynaptic knockdown of the fly homologue of LRRK2 thwarts retrograde, homeostatic synaptic compensation at the larval neuromuscular junction. Conversely, postsynaptic overexpression of either the fly or human LRRK2 transgene induces a retrograde enhancement of presynaptic neurotransmitter release by increasing the size of the release ready pool of vesicles. We show that LRRK2 promotes cap-dependent translation and identify Furin 1 as its translational target, which is required for the synaptic function of LRRK2. As the regulation of synaptic homeostasis plays a fundamental role in ensuring normal and stable synaptic function, our findings suggest that aberrant function of LRRK2 may lead to destabilization of neural circuits.

Development and initial outcomes of an upper gastrointestinal multidisciplinary clinic.

INTRODUCTION: Patients with upper gastrointestinal cancer are often comorbid and require complex surgical treatments for their cancers, meaning that their preoperative assessment can be based around numerous outpatient assessments with multiple services. A multidisciplinary clinic (MDC) was developed for the assessment of patients with confirmed or suspected upper gastrointestinal cancers. METHODS: Face-to-face meetings were held between stakeholder services at Waitemata District Health Board, and clinic resource allocated. Significant IT modification of existing clinic booking software was required. RESULTS: Between September 2014, and September 2015, there were a total of 165 new patient, and 710 follow-up appointments. All new patients were seen by a surgeon and then other specialties. Of the 165 new patient appointments, 146 (88%) patients had a definitive treatment plan in place and were cleared by anaesthesia and intensive care at the end of the clinic. Staff and patients report high levels of satisfaction for the clinic. CONCLUSION: A dedicated MDC has provided a single forum where complex patients can be reviewed, and a definitive treatment plan formulated in nearly 90% of patients, even when this involves multiple medical and paramedical specialties with high levels of patient and clinician satisfaction.

Degradable poly(apigenin) polymer inhibits tumor cell adhesion to vascular endothelial cells.

Cancer and the inflammatory system share a complex intertwined relationship. For instance, in response to an injury or stress, vascular endothelial cells will express cell adhesion molecules as a means of recruiting leukocytes. However, circulating tumor cells (CTCs) have been shown to highjack this expression for the adhesion and invasion during the metastatic cascade. As such, the initiation of endothelial cell inflammation, either by surgical procedures (cancer resection) or chemotherapy can inadvertently increase the metastatic potential of CTCs. Yet, systemic delivery of anti-inflammatories, which weaken the entire immune system, may not be preferred in some treatment settings. In this work, we demonstrate that a long-term releasing flavone-based polymer and subsequent nanoparticle delivery system can inhibit tumor cell adhesion, through the suppression of endothelial cell adhesion molecule expression. The degradation of a this anti-inflammatory polymer provides longer term, localized release profile of active therapeutic drug in nanoparticle form as compared with that of the free drug, permitting more targeted anti-metastatic therapies. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1438-1447, 2016.

Anthropometry and blood pressure differences in black Caribbean, African, South Asian and white adolescents: the MRC DASH study.

OBJECTIVES: In this first large-scale study of ethnic differences in blood pressure (BP) among British adolescents, we examine the differences in BP levels in adolescence and the extent to which age, sex, body size and stage of maturation affect any observed differences. METHOD: A total of 6365 11-13 year olds (including 1189 white, 907 black Caribbeans and 1056 black Africans, 473 Indians, 605 Pakistanis and Bangladeshis, and 548 of mixed ethnicity) had systolic blood pressure (SBP) and diastolic blood pressure (DBP), anthropometry and pubertal stage measured in 2003. RESULTS: Compared with their white UK counterparts, black Caribbean and African boys were taller, and black Caribbean and African girls were taller, larger and matured earlier. Except for DBP among Indian girls, BP in minority groups was generally lower than in white UK children. Adjusted for age, height and body mass index, mean SBP was 109.1 mmHg (95% confidence interval 108.4, 109.8) and DBP 65.7 mmHg (65.2, 66.3) among white UK boys. Black Caribbean boys had lower SBP (-2.0; -3.2, -0.9 mmHg) and DBP (-1.5; -2.3, -0.6), and black African (-2.3; -3.4, -1.2) and mixed ethnicity (-1.6; -2.9, -0.3) boys had lower SBP. Adjusted SBP was 108.5 (107.8, 109.3) and DBP was 67.5 mmHg (66.9, 68.1) among white UK girls. Pakistani (-1.8; -3.2, -0.4) and black African (-1.1; -1.9, -0.3) girls had lower SBP and Indian girls (1.2; 0.1, 2.4) had higher DBP. Unlike African American girls, late puberty was not associated with higher BP in minority groups. CONCLUSION: At these ages, the ethnic-specific patterns in BP in adulthood were not observed. Apart from higher DBP for Indian girls, BP in minority groups was generally lower than their white UK counterparts. Targeting intervention in adolescence may be a critical opportunity for preventing ethnic differences in BP in later life.