Scalable Hypothalamic Arcuate Neuron Differentiation from Human Pluripotent Stem Cells Suitable for Modeling Metabolic and Reproductive Disorders.

The hypothalamus, composed of several nuclei, is essential for maintaining our body's homeostasis. The arcuate nucleus (ARC), located in the mediobasal hypothalamus, contains neuronal populations with eminent roles in energy and glucose homeostasis as well as reproduction. These neuronal populations are of great interest for translational research. To fulfill this promise, we used a robotic cell culture platform to provide a scalable and chemically defined approach for differentiating human pluripotent stem cells (hPSCs) into pro-opiomelanocortin (POMC), somatostatin (SST), tyrosine hydroxylase (TH) and gonadotropin-releasing hormone (GnRH) neuronal subpopulations with an ARC-like signature. This robust approach is reproducible across several distinct hPSC lines and exhibits a stepwise induction of key ventral diencephalon and ARC markers in transcriptomic profiling experiments. This is further corroborated by direct comparison to human fetal hypothalamus, and the enriched expression of genes implicated in obesity and type 2 diabetes (T2D). Genome-wide chromatin accessibility profiling by ATAC-seq identified accessible regulatory regions that can be utilized to predict candidate enhancers related to metabolic disorders and hypothalamic development. In depth molecular, cellular, and functional experiments unveiled the responsiveness of the hPSC-derived hypothalamic neurons to hormonal stimuli, such as insulin, neuropeptides including kisspeptin, and incretin mimetic drugs such as Exendin-4, highlighting their potential utility as physiologically relevant cellular models for disease studies. In addition, differential glucose and insulin treatments uncovered adaptability within the generated ARC neurons in the dynamic regulation of POMC and insulin receptors. In summary, the establishment of this model represents a novel, chemically defined, and scalable platform for manufacturing large numbers of hypothalamic arcuate neurons and serves as a valuable resource for modeling metabolic and reproductive disorders.

hPSC-Derived Astrocytes at the Forefront of Translational Applications in Neurological Disorders.

Astrocytes, the most abundant glial cell type in the brain, play crucial roles in maintaining homeostasis within the central nervous system (CNS). Impairment or abnormalities of typical astrocyte functions in the CNS serve as a causative or contributing factor in numerous neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. Currently, disease-modeling and drug-screening approaches, primarily focused on human astrocytes, rely on human pluripotent stem cell (hPSC)-derived astrocytes. However, it is important to acknowledge that these hPSC-derived astrocytes exhibit notable differences across studies and when compared to their in vivo counterparts. These differences may potentially compromise translational outcomes if not carefully accounted for. This review aims to explore state-of-the-art in vitro models of human astrocyte development, focusing on the developmental processes, functional maturity, and technical aspects of various hPSC-derived astrocyte differentiation protocols. Additionally, it summarizes their successful application in modeling neurological disorders. The discussion extends to recent advancements in the large-scale production of human astrocytes and their application in developing high-throughput assays conducive to therapeutic drug discovery.

Multimodal decoding of human liver regeneration.

The liver has a unique ability to regenerate1,2; however, in the setting of acute liver failure (ALF), this regenerative capacity is often overwhelmed, leaving emergency liver transplantation as the only curative option3-5. Here, to advance understanding of human liver regeneration, we use paired single-nucleus RNA sequencing combined with spatial profiling of healthy and ALF explant human livers to generate a single-cell, pan-lineage atlas of human liver regeneration. We uncover a novel ANXA2+ migratory hepatocyte subpopulation, which emerges during human liver regeneration, and a corollary subpopulation in a mouse model of acetaminophen (APAP)-induced liver regeneration. Interrogation of necrotic wound closure and hepatocyte proliferation across multiple timepoints following APAP-induced liver injury in mice demonstrates that wound closure precedes hepatocyte proliferation. Four-dimensional intravital imaging of APAP-induced mouse liver injury identifies motile hepatocytes at the edge of the necrotic area, enabling collective migration of the hepatocyte sheet to effect wound closure. Depletion of hepatocyte ANXA2 reduces hepatocyte growth factor-induced human and mouse hepatocyte migration in vitro, and abrogates necrotic wound closure following APAP-induced mouse liver injury. Together, our work dissects unanticipated aspects of liver regeneration, demonstrating an uncoupling of wound closure and hepatocyte proliferation and uncovering a novel migratory hepatocyte subpopulation that mediates wound closure following liver injury. Therapies designed to promote rapid reconstitution of normal hepatic microarchitecture and reparation of the gut-liver barrier may advance new areas of therapeutic discovery in regenerative medicine.

Maternal immunization with distinct influenza vaccine platforms elicits unique antibody profiles that impact the protection of offspring.

Pregnant women and infants are considered high-risk groups for increased influenza disease severity. While influenza virus vaccines are recommended during pregnancy, infants cannot be vaccinated until at least six months of age. Passive transfer of maternal antibodies (matAbs) becomes vital for the infant's protection. Here, we employed an ultrasound-based timed-pregnancy murine model and examined matAb responses to distinct influenza vaccine platforms and influenza A virus (IAV) infection in dams and their offspring. We demonstrate vaccinating dams with a live-attenuated influenza virus (LAIV) vaccine or recombinant hemagglutinin (rHA) proteins administered with adjuvant resulted in enhanced and long-lasting immunity and protection from influenza in offspring. In contrast, a trivalent split-inactivated vaccine (TIV) afforded limited protection in our model. By cross-fostering pups, we show the timing of antibody transfer from vaccinated dams to their offspring (prenatal versus postnatal) can shape the antibody profile depending on the vaccine platform. Our studies provide information on how distinct influenza vaccines lead to immunogenicity and efficacy during pregnancy, impact the protection of their offspring, and detail roles for IgG1 and IgG2c in the development of vaccine administration during pregnancy that stimulate and measure expression of both antibody subclasses.

Patterns and distribution of regional nodal involvement and recurrence in a surgically treated oropharyngeal squamous cell carcinoma cohort at a tertiary center.

OBJECTIVES: To investigate and describe the patterns of regional metastases and recurrences after surgical treatment of oropharyngeal squamous cell cancer (OPSCC). MATERIALS AND METHODS: Retrospective study of patients diagnosed with OPSCC from 2006 to 2021 at a tertiary referral center. Only patients treated with surgery including a neck dissection were included. Patients with unknown human papillomavirus (HPV) status, prior head and neck cancer, distant metastases, or synchronous head and neck cancer were excluded. RESULTS: A total of 928 patients were included. 89% were males, the average age was 58.6 years (range: 25.2-87.5), 874 (94%) were HPV(+), and 513 (55.3%) had a tonsil cancer. Among cN + patients, the most commonly involved levels at presentation were level II (85.2%), level III (33.3%), and level IV (9.4%). In cN0 patients, metastases were only observed in level II (16.2%) and level III (9.2%). Nodal recurrence occurred in 48 (5.2%) patients after a median time of 1.0 years (interquartile range: 0.6-2.0). Nodal recurrence incidence was similar in HPV(+) and HPV(-) patients (5.0% vs. 7.4%, p = 0.44). The most common levels for regional recurrence were ipsilateral level II (45.8%), contralateral level II (43.8%), and ipsilateral level V (25.0%). Multivariable analysis revealed that pN was a significant predictor for regional recurrence (p = 0.02). CONCLUSION: There is no difference in the distribution of regional metastases and recurrences in HPV(+) and HPV(-) OPSCC patients. Our findings align with the established understanding that regional metastases predominantly manifest in the ipsilateral level II-IV at presentation. Moreover, the data support the clinical recommendation to restrict elective neck dissection in cN0 patients to ipsilateral levels IIa and III, excluding level IIb. Regional recurrence is significantly associated with pN status.

Bladder perforation as a rare complication of urethra sounding with a blunt marking pen.

Urethral sounding is the insertion of an object or liquid into the urethra for sexual gratification. It is associated with a substantial risk of loss of the foreign body in the bladder, urethral strictures or infection. Bladder perforation is a rare complication of urethral sounding which is usually associated with a sharp object. Here, we present the case of a young adult female presenting with abdominal pain after practicing urethral sounding with a blunt marking pen. She was found to have an intraperitoneal bladder perforation, requiring exploratory laparotomy and bladder repair.

Different Methods for Traumatic Brain Injury Diagnosis Influence Presence and Symptoms of Post-Concussive Syndrome in United States Veterans.

Common methods for evaluating history of traumatic brain injury (TBI) include self-report, electronic medical record review (EMR), and structured interviews such as the Head Trauma Events Characteristics (HTEC). Each has strengths and weaknesses, but little is known regarding how TBI diagnostic rates or the associated symptom profile differ among them. This study examined 200 Veterans recruited within the VA Portland Health Care System, each evaluated for TBI using self-report, EMR, and HTEC. Participants also completed validated questionnaires assessing chronic symptom severity in broad health-related domains (pain, sleep, quality of life, post-concussive symptoms). The HTEC was more sensitive (80% of participants in our cohort) than either self-report or EMR alone (40%). As expected from the high sensitivity, participants screening positive for TBI through the HTEC included many people with mild or no post-concussive symptoms. Participants were grouped according to degree of concordance across these diagnostic methods: no TBI, n = 43; or TBI-positive in any one method (TBI-1dx, n = 53), positive in any two (TBI-2dx, n = 45), or positive in all three (TBI-3dx, n = 59). The symptom profile of the TBI-1dx group was indistinguishable from the no TBI group. The TBI-3dx group had the most severe symptom profile. Our results show that understanding the exact methods used to ascertain TBI is essential when interpreting results from other studies, given that results and conclusions may differ dramatically depending on the method. This issue will become even more critical when interpreting data merged from multiple sources within newer, centralized repositories (e.g., Federal Interagency Traumatic Brain Injury Research [FITBIR]).

Non-canonical Wnt signalling regulates scarring in biliary disease via the planar cell polarity receptors.

The number of patients diagnosed with chronic bile duct disease is increasing and in most cases these diseases result in chronic ductular scarring, necessitating liver transplantation. The formation of ductular scaring affects liver function; however, scar-generating portal fibroblasts also provide important instructive signals to promote the proliferation and differentiation of biliary epithelial cells. Therefore, understanding whether we can reduce scar formation while maintaining a pro-regenerative microenvironment will be essential in developing treatments for biliary disease. Here, we describe how regenerating biliary epithelial cells express Wnt-Planar Cell Polarity signalling components following bile duct injury and promote the formation of ductular scars by upregulating pro-fibrogenic cytokines and positively regulating collagen-deposition. Inhibiting the production of Wnt-ligands reduces the amount of scar formed around the bile duct, without reducing the development of the pro-regenerative microenvironment required for ductular regeneration, demonstrating that scarring and regeneration can be uncoupled in adult biliary disease and regeneration.

Resolving the fibrotic niche of human liver cirrhosis at single-cell level.

Liver cirrhosis is a major cause of death worldwide and is characterized by extensive fibrosis. There are currently no effective antifibrotic therapies available. To obtain a better understanding of the cellular and molecular mechanisms involved in disease pathogenesis and enable the discovery of therapeutic targets, here we profile the transcriptomes of more than 100,000 single human cells, yielding molecular definitions for non-parenchymal cell types that are found in healthy and cirrhotic human liver. We identify a scar-associated TREM2+CD9+ subpopulation of macrophages, which expands in liver fibrosis, differentiates from circulating monocytes and is pro-fibrogenic. We also define ACKR1+ and PLVAP+ endothelial cells that expand in cirrhosis, are topographically restricted to the fibrotic niche and enhance the transmigration of leucocytes. Multi-lineage modelling of ligand and receptor interactions between the scar-associated macrophages, endothelial cells and PDGFRα+ collagen-producing mesenchymal cells reveals intra-scar activity of several pro-fibrogenic pathways including TNFRSF12A, PDGFR and NOTCH signalling. Our work dissects unanticipated aspects of the cellular and molecular basis of human organ fibrosis at a single-cell level, and provides a conceptual framework for the discovery of rational therapeutic targets in liver cirrhosis.

N-Methyl-d-aspartate receptor co-agonist availability affects behavioral and neurochemical responses to cocaine: insights into comorbid schizophrenia and substance abuse.

Both schizophrenia (SZ) and substance abuse (SA) exhibit significant heritability. Moreover, N-methyl-d-aspartate receptors (NMDARs) have been implicated in the pathophysiology of both SZ and SA. We hypothesize that the high prevalence of comorbid SA in SZ is due to dysfunction of NMDARs caused by shared risk genes. We used transgenic mice with a null mutation of the gene encoding serine racemase (SR), the enzyme that synthesizes the NMDAR co-agonist d-serine and an established risk gene for SZ, to recreate the pathology of SZ. We determined the effect of NMDAR hypofunction resulting from the absence of d-serine on motivated behavior by using intracranial self-stimulation and neurotransmitter release in the nucleus accumbens by using in vivo microdialysis. Compared with wild-type mice, SR-/- mice exhibited similar baseline intracranial self-stimulation thresholds but were less sensitive to the threshold-lowering (rewarding) and the performance-elevating (stimulant) effects of cocaine. While basal dopamine (DA) and glutamate release were elevated in the nucleus accumbens of SR-/- mice, cocaine-induced increases in DA and glutamate release were blunted. γ-Amino-butyric acid efflux was unaffected in the SR-/- mice. Together, these findings suggest that the impaired NMDAR function and a consequent decrease in sensitivity to cocaine effects on behavior are mediated by blunted DA and glutamate responses normally triggered by the drug. Projected to humans, NMDAR hypofunction due to mutations in SR or other genes impacting glutamatergic function in SZ may render abused substances less potent and effective, thus requiring higher doses to achieve a hedonic response, resulting in elevated drug exposure and increased dependence/addiction.

Systematic review of management of incidental gallbladder cancer after cholecystectomy.

BACKGROUND: Gallbladder cancer is rare, but cancers detected incidentally after cholecystectomy are increasing. The aim of this study was to review the available data for current best practice for optimal management of incidental gallbladder cancer. METHODS: A systematic PubMed search of the English literature to May 2018 was conducted. RESULTS: The search identified 12 systematic reviews and meta-analyses, in addition to several consensus reports, multi-institutional series and national audits. Some 0·25-0·89 per cent of all cholecystectomy specimens had incidental gallbladder cancer on pathological examination. Most patients were staged with pT2 (about half) or pT1 (about one-third) cancers. Patients with cancers confined to the mucosa (T1a or less) had 5-year survival rates of up to 100 per cent after cholecystectomy alone. For cancers invading the muscle layer of the gallbladder wall (T1b or above), reresection is recommended. The type, extent and timing of reresection remain controversial. Observation time may be used for new cross-sectional imaging with CT and MRI. Perforation at initial surgery had a higher risk of disease dissemination. Gallbladder cancers are PET-avid, and PET may detect residual disease and thus prevent unnecessary surgery. Routine laparoscopic staging before reresection is not warranted for all stages. Risk of peritoneal carcinomatosis increases with each T category. The incidence of port-site metastases is about 10 per cent. Routine resection of port sites has no effect on survival. Adjuvant chemotherapy is poorly documented and probably underused. CONCLUSION: Management of incidental gallbladder cancer continues to evolve, with more refined suggestions for subgroups at risk and a selective approach to reresection.

Dysbindin-1 contributes to prefrontal cortical dendritic arbor pathology in schizophrenia.

Deep layer III pyramidal cells in the dorsolateral prefrontal cortex (DLPFC) from subjects with schizophrenia and bipolar disorder previously were shown to exhibit dendritic arbor pathology. This study sought to determine whether MARCKS, its regulatory protein dysbindin-1, and two proteins, identified using microarray data, CDC42BPA and ARHGEF6, were associated with dendritic arbor pathology in the DLPFC from schizophrenia and bipolar disorder subjects. Using western blotting, relative protein expression was assessed in the DLPFC (BA 46) grey matter from subjects with schizophrenia (n = 19), bipolar disorder (n = 17) and unaffected control subjects (n = 19). Protein expression data were then correlated with dendritic parameter data obtained previously. MARCKS and dysbindin-1a expression levels did not differ among the three groups. Dysbindin-1b expression was 26% higher in schizophrenia subjects (p = 0.01) and correlated inversely with basilar dendrite length (r = -0.31, p = 0.048) and the number of spines per basilar dendrite (r = -0.31, p = 0.048), but not with dendritic spine density (r = -0.16, p = 0.32). The protein expression of CDC42BPA was 33% higher in schizophrenia subjects (p = 0.03) but, did not correlate with any dendritic parameter (p > 0.05). ARHGEF6 87 kDa isoform expression did not differ among the groups. CDC42BPA expression was not altered in frontal cortex from rats chronically administered haloperidol or clozapine. Dysbindin-1b appears to play a role in dendritic arbor pathology observed previously in the DLPFC in schizophrenia.

Utility and cost evaluation of multiparametric magnetic resonance imaging for the assessment of non-alcoholic fatty liver disease.

BACKGROUND: Validated diagnostic tools that are accurate, cost effective and acceptable to patients are required for disease stratification and monitoring in NAFLD. AIMS: To investigate the performance and cost of multiparametric MRI alongside existing biomarkers in the assessment of NAFLD. METHODS: Adult patients undergoing standard of care liver biopsy for NAFLD were prospectively recruited at two UK liver centres and underwent multiparametric MRI, blood sampling and transient elastography withing 2 weeks of liver biopsy. Non-invasive markers were compared to histology as the gold standard. RESULTS: Data were obtained in 50 patients and 6 healthy volunteers. Corrected T1 (cT1) correlated with NAFLD activity score (ρ = 0.514, P < .001). cT1, enhanced liver fibrosis (ELF) test and liver stiffness differentiated patients with simple steatosis and NASH with AUROC (95% CI) of 0.69 (0.50-0.88), 0.87 (0.77-0.79) and 0.82 (0.70-0.94) respectively and healthy volunteers from patients with AUROC (95% CI) of 0.93 (0.86-1.00), 0.81 (0.69-0.92) and 0.89 (0.77-1.00) respectively. For the risk stratification of NAFLD, multiparametric MRI could save £150,218 per 1000 patients compared to biopsy. Multiparametric MRI did not discriminate between individual histological fibrosis stages in this population (P = .068). CONCLUSIONS: Multiparametric MRI accurately identified patients with steatosis, stratifies those with NASH or simple steatosis and reliably excludes clinically significant liver disease with superior negative predictive value (83.3%) to liver stiffness (42.9%) and ELF (57.1%). For the risk stratification of NAFLD, multiparametric MRI was cost effective and, combined with transient elastography, had the lowest cost per correct diagnosis.

αv integrins on mesenchymal cells regulate skeletal and cardiac muscle fibrosis.

Mesenchymal cells expressing platelet-derived growth factor receptor beta (PDGFRß) are known to be important in fibrosis of organs such as the liver and kidney. Here we show that PDGFRß+ cells contribute to skeletal muscle and cardiac fibrosis via a mechanism that depends on αv integrins. Mice in which αv integrin is depleted in PDGFRß+ cells are protected from cardiotoxin and laceration-induced skeletal muscle fibrosis and angiotensin II-induced cardiac fibrosis. In addition, a small-molecule inhibitor of αv integrins attenuates fibrosis, even when pre-established, in both skeletal and cardiac muscle, and improves skeletal muscle function. αv integrin blockade also reduces TGFß activation in primary human skeletal muscle and cardiac PDGFRß+ cells, suggesting that αv integrin inhibitors may be effective for the treatment and prevention of a broad range of muscle fibroses.

Comparison of Thaumarchaeotal populations from four deep sea basins.

The nitrogen cycle in the marine environment is strongly affected by ammonia-oxidizing Thaumarchaeota. In some marine settings, Thaumarchaeotes can comprise a large percentage of the prokaryotic population. To better understand the biogeographic patterns of Thaumarchaeotes, we sought to investigate differences in their abundance and phylogenetic diversity between geographically distinct basins. Samples were collected from four marine basins (The Caspian Sea, the Great Australian Bight, and the Central and Eastern Mediterranean). The concentration of bacterial and archaeal 16S rRNA genes and archaeal amoA genes were assessed using qPCR. Minimum entropy decomposition was used to elucidate the fine-scale diversity of Thaumarchaeotes. We demonstrated that there were significant differences in the abundance and diversity of Thaumarchaeotes between these four basins. The diversity of Thaumarchaeotal oligotypes differed between basins with many oligotypes only present in one of the four basins, which suggests that their distribution showed biogeographic patterning. There were also significant differences in Thaumarchaeotal community structure between these basins. This would suggest that geographically distant, yet geochemically similar basins may house distinct Thaumarchaeaotal populations. These findings suggest that Thaumarchaeota are very diverse and that biogeography in part contributes in determining the diversity and distribution of Thaumarchaeotes.

Effectiveness of prophylactic antibiotics in outpatient plastic surgery.

BACKGROUND: The effectiveness of prophylactic antibiotics has not been established for patients who undergo plastic surgery as outpatients, and consensus guidelines for antibiotic administration in clean-contaminated plastic surgery are not available. OBJECTIVES: In a retrospective study of outpatients, the authors examined preoperative timing of prophylactic antibiotics, whether postoperative antibiotics were administered, and whether any correlations existed between these practices and surgical complications. METHODS: The medical records of 468 plastic surgery outpatients were reviewed. Collected data included preoperative antibiotic timing, postoperative antibiotic use, comorbidities, and complications. Rates of complications were calculated and compared with other data. RESULTS: All 468 patients received antibiotics preoperatively, but only 93 (19.9%) received them ≥1 hour before the initial incision. Antibiotics were administered 15 to 44 minutes before surgery in 217 patients (46.4%). There was no significant difference in complication rates between the 315 patients who received postoperative prophylactic antibiotics (16.2%) and the 153 who did not (20.9%). Comorbidities had no bearing on postoperative complications. CONCLUSIONS: Postoperative antibiotic prophylaxis may be unnecessary for outpatient plastic surgery patients. LEVEL OF EVIDENCE: 3.

Transposon based activation tagging in diploid strawberry and monoploid derivatives of potato.

KEY MESSAGE: Diploid strawberry and potato transformed with a transposon tagging construct exhibited either global (strawberry) or local transposition (potato). An activation tagged, compact-sized strawberry mutant overexpressed the gene adjacent to Ds. As major fruit and vegetable crops, respectively, strawberry and potato are among the first horticultural crops with draft genome sequences. To study gene function, we examined transposon-tagged mutant strategies in model populations for both species, Fragaria vesca and Solanum tuberosum Group Phureja, using the same Activation/Dissociation (Ac/Ds) construct. Early somatic transposition during tissue culture occurred at a frequency of 18.5% in strawberry but not in potato transformants. Green fluorescent protein under a monocot promoter was a more reliable selectable marker in strawberry compared to potato. BASTA (gluphosinate herbicide) resistance served as an effective selectable marker for both species (80 and 85% reliable in strawberry and potato, respectively), although the effective concentration differed (0.5% for strawberry and 0.03% for potato). Transposons preferentially reinserted within genes (exons and introns) in both species. Real-time quantitative PCR revealed enhanced gene expression (670 and 298-fold expression compared to wild type in petiole and leaf tissue, respectively) for an activation tagged strawberry mutant with Ds inserted about 0.6 kb upstream from a gene coding for an epidermis-specific secreted glycoprotein EP1. Our data also suggested that endopolyploid (diploid) cells occurring in leaf explants of monoploid potato were the favored targets of T-DNA integration during transformation. Mutants obtained in these studies provide a useful resource for future genetic studies.

Standardized method for the harvest of nonhuman primate tissue optimized for multiple modes of analyses.

Appropriate animal models are critical to conduct translational studies of human disorders without variables that can confound clinical studies. Such analytic methods as patch-clamp electrophysiological and voltammetric recordings of neurons in brain slices require living brain tissue. In order to obtain viable tissue from nonhuman primate brains, tissue collection methods must be designed to preserve cardiovascular and respiratory functions for as long as possible. This paper describes a method of necropsy that has been used in three species of monkeys that satisfies this requirement. At necropsy, animals were maintained under a deep surgical plane of anesthesia while a craniotomy was conducted to expose the brain. Following the craniotomy, animals were perfused with ice-cold, oxygenated artificial cerebrospinal fluid to displace blood and to reduce the temperature of the entire brain. The brain was removed within minutes of death and specific brain regions were immediately dissected for subsequent in vitro electrophysiology or voltammetry experiments. This necropsy method also provided for the collection of tissue blocks containing all brain regions that were immediately frozen and stored for subsequent genomic, proteomic, autoradiographic and histological studies. An added benefit from the design of this necropsy method is that all major peripheral tissues were also collected and are now being utilized in a wide range of genomic, biochemical and histological assays. This necropsy method has resulted in the establishment and growth of a nonhuman primate alcohol tissue bank designed to distribute central nervous system and peripheral tissues to the larger scientific community.

TC-8831, a nicotinic acetylcholine receptor agonist, reduces L-DOPA-induced dyskinesia in the MPTP macaque.

Long-term L-DOPA treatment for Parkinson's disease (PD) is limited by motor complications, particularly L-DOPA-induced dyskinesia (LID). A therapy with the ability to ameliorate LID without reducing anti-parkinsonian benefit would be of great value. We assessed the ability of TC-8831, an agonist at nicotinic acetylcholine receptors (nAChR) containing α6ß2/α4ß2 subunit combinations, to provide such benefits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine- (MPTP) lesioned macaques with established LID. Animals were treated orally for consecutive 14-day periods with twice-daily vehicle (weeks 1-2) or TC-8831 (0.03, 0.1 or 0.3 mg/kg, weeks 3-8). L-DOPA was also administered, once-daily, (weeks 1-12, median-dose 30 mg/kg, p.o.). For the following two-weeks (weeks 9-10), TC-8831 was washed out, while once-daily L-DOPA treatment was maintained. The effects of once-daily amantadine (3 mg/kg, p.o.) were then assessed over weeks 11-12. LID, parkinsonism, duration and quality of ON-time were assessed weekly by a neurologist blinded to treatment. TC-8831 reduced the duration of 'bad' ON-time (ON-time with disabling dyskinesia) by up to 62% and decreased LID severity (median score 18 cf. 34 (vehicle), 0.1 mg/kg, 1-3 h period). TC-8831 also significantly reduced choreiform and dystonic dyskinesia (median scores 6 and 31 cf. 19 and 31 respectively (vehicle), both 0.03 mg/kg, 1-3 h). At no time did TC-8831 treatment result in a reduction in anti-parkinsonian benefit of L-DOPA. By comparison, amantadine also significantly reduced dyskinesia and decreased 'bad' ON-time (up to 61%) but at the expense of total ON-time (reduced by up to 23%). TC-8831 displayed robust anti-dyskinetic actions and improved the quality of ON-time evoked by L-DOPA without any reduction in anti-parkinsonian benefit.