Deficits in basal and evoked striatal dopamine release following alpha-synuclein preformed fibril injection: An in vivo microdialysis study

Parkinson's disease (PD) is characterized by the accumulation of misfolded alpha-synuclein (α-syn) protein, forming intraneuronal Lewy body (LB) inclusions. The α-syn preformed fibril (PFF) model of PD recapitulates α-syn aggregation, progressive nigrostriatal degeneration and motor dysfunction; however, little is known about the time course of PFF-induced alterations in basal and evoked dopamine (DA). In vivo microdialysis is well suited for identifying small changes in neurotransmitter levels over extended periods. In the present study, adult male Fischer 344 rats received unilateral, intrastriatal injections of either α-syn PFFs or phosphate-buffered saline (PBS). At 4 or 8 months post-injection (p.i.), animals underwent in vivo microdialysis to evaluate basal extracellular striatal DA and metabolite levels, local KCl-evoked striatal DA release and the effects of systemic levodopa (l-DOPA). Post-mortem analysis demonstrated equivalent PFF-induced reductions in tyrosine hydroxylase (TH) immunoreactive nigral neurons (~50%) and striatal TH (~20%) at both time points. Compared with reduction in striatal TH, reduction in striatal dopamine transporter (DAT) was more pronounced and progressed between the 4- and 8-month p.i. intervals (36% ➔ 46%). Significant PFF-induced deficits in basal and evoked striatal DA, as well as deficits in motor performance, were not observed until 8 months p.i. Responses to l-DOPA did not differ regardless of PBS or PFF treatment. These results suggest that basal and evoked striatal DA are maintained for several months following PFF injection, with loss of both associated with motor dysfunction. Our studies provide insight into the time course and magnitude of PFF-induced extracellular dopaminergic deficits in the striatum.

Broad Serotonergic Actions of Vortioxetine as a Promising Avenue for the Treatment of L-DOPA-Induced Dyskinesia

Parkinson's Disease (PD) is a neurodegenerative disorder characterized by motor symptoms that result from loss of nigrostriatal dopamine (DA) cells. While L-DOPA provides symptom alleviation, its chronic use often results in the development of L-DOPA-induced dyskinesia (LID). Evidence suggests that neuroplasticity within the serotonin (5-HT) system contributes to LID onset, persistence, and severity. This has been supported by research showing 5-HT compounds targeting 5-HT1A/1B receptors and/or the 5-HT transporter (SERT) can reduce LID. Recently, vortioxetine, a multimodal 5-HT compound developed for depression, demonstrated acute anti-dyskinetic effects. However, the durability and underlying pharmacology of vortioxetine's anti-dyskinetic actions have yet to be delineated. To address these gaps, we used hemiparkinsonian rats in Experiment 1, examining the effects of sub-chronic vortioxetine on established LID and motor performance. In Experiment 2, we applied the 5-HT1A antagonist WAY-100635 or 5-HT1B antagonist SB-224289 in conjunction with L-DOPA and vortioxetine to determine the contributions of each receptor to vortioxetine's effects. The results revealed that vortioxetine consistently and dose-dependently attenuated LID while independently, 5-HT1A and 5-HT1B receptors each partially reversed vortioxetine's effects. Such findings further support the promise of pharmacological strategies, such as vortioxetine, and indicate that broad 5-HT actions may provide durable responses without significant side effects.

Characterizing the relationship between L-DOPA-induced-dyskinesia and psychosis-like behaviors in a bilateral rat model of Parkinson's disease

Parkinson's disease associated psychosis (PDAP) is a prevalent non-motor symptom (NMS) that significantly erodes patients' and caregivers' quality of life yet remains vastly understudied. One potential source of PDAP in late-stage Parkinson's disease (PD) is the common dopamine (DA) replacement therapy for motor symptoms, Levodopa (L-DOPA). Given the high incidence of L-DOPA-induced dyskinesia (LID) in later phases of PD, this study sought to characterize the relationship between PDAP and LID in a bilateral medial forebrain bundle 6-hydroxydopamine hydrobromide (6-OHDA) lesion rat model. To assess PDAP in this model, prepulse inhibition (PPI), a well-validated assay of sensorimotor gating, was employed. First, we tested whether a bilateral lesion alone or after chronic L-DOPA treatment was sufficient to induce PPI dysfunction. Rats were also monitored for LID development, using the abnormal involuntary movements (AIMs) test, to examine PPI and LID associations. In experiment 2, Vilazodone (VZD), a serotonin transporter (SERT) blocker and 1A receptor (5-HT_1A) partial agonist was administered to test its potential efficacy in reducing LID and PPI dysfunction. Once testing was complete, tissue was collected for high performance liquid chromatography (HPLC) to examine the monoamine levels in motor and non-motor circuits. Results indicate that bilateral DA lesions produced motor deficits and that chronic L-DOPA induced moderate AIMs; importantly, rats that developed more severe AIMs were more likely to display sensorimotor gating dysfunction. In addition, VZD treatment dose-dependently reduced L-DOPA-induced AIMs without impairing L-DOPA efficacy, although VZD's effects on PPI were limited. Altogether, this project established the bilateral 6-OHDA lesion model accurately portrayed LID and PDAP-like behaviors, uncovered their potential relationship, and finally, demonstrated the utility of VZD for reducing LID.

BTLA+CD200+ B cells dictate the divergent immune landscape and immunotherapeutic resistance in metastatic vs. primary pancreatic cancer

Response to cancer immunotherapy in primary versus metastatic disease has not been well-studied. We found primary pancreatic ductal adenocarcinoma (PDA) is responsive to diverse immunotherapies whereas liver metastases are resistant. We discovered divergent immune landscapes in each compartment. Compared to primary tumor, liver metastases in both mice and humans are infiltrated by highly anergic T cells and MHCII^loIL10⁺ macrophages that are unable to present tumor-antigen. Moreover, a distinctive population of CD24⁺CD44^-CD40^- B cells dominate liver metastases. These B cells are recruited to the metastatic milieu by Muc1^hiIL18^hi tumor cells, which are enriched >10-fold in liver metastases. Recruited B cells drive macrophage-mediated adaptive immune-tolerance via CD200 and BTLA. Depleting B cells or targeting CD200/BTLA enhanced macrophage and T-cell immunogenicity and enabled immunotherapeutic efficacy of liver metastases. Our data detail the mechanistic underpinnings for compartment-specific immunotherapy-responsiveness and suggest that primary PDA models are poor surrogates for evaluating immunity in advanced disease.

The psychology of gastric bypass surgery

BACKGROUND

This article discusses the importance of psychological evaluation of gastric bypass (GBP) surgery candidates and post-surgical psychological support services, using the Center for Weight Reduction Surgery at Montefiore Medical Center as a model. The study of psychological predictors of post-operative outcome is in its beginning stages, and the small body of literature on this topic is reviewed.

METHODS

115 GBP surgery candidates completed a clinical interview and a self-report measure, the MMPI-2.

RESULTS AND CONCLUSIONS

A high prevalence of psychopathology and personality disturbance was found in this population. The impact that psychological disturbance may have on post-operative outcome is discussed. The authors also provide a qualitative analysis of the psychological themes commonly found among this population, as well as psychosocial interventions that have been found helpful.

Youth suicidal behavior: assessment and intervention

In this article, the authors review the research on risk assessment of suicidal adolescents and describe the small body of randomized-clinical-treatment trials for this population. Research has yielded a fairly consistent set of direct and indirect risk factors for suicidal behavior in adolescents. The authors describe a variety of measures commonly used to assess these risk factors. Treatment studies targeting suicide are sparse for all ages. In the adult literature, evidence suggests clozapine, depot flupenthixol, lithium, and dialectical behavior therapy (DBT) are significantly more effective in decreasing suicidal behavior than placebo or Treatment as Usual. For adolescents, it is difficult to draw conclusions about treatment efficacy. In general, control conditions are just as effective at reducing suicidal behavior as experimental conditions. While some novel interventions for suicidal adolescents are described, there is a desperate need for more research to be conducted in order to advance this burgeoning field.

Purification and crystallization of rhizopuspepsin: the use of nickel chelation chromatography to select for catalytically active species

A new method to obtain pure zymogen-derived peptidases is presented. The key strategy is to install a polyhistidine peptide tag on the N-terminus of the propeptide sequence of a zymogen. After expression, purification, and folding of the protein, autocatalytic posttranslational cleavage and filtration through a nickel affinity column gives pure, functional peptidase. This method takes advantage of the nickel affinity chromatography system that removes both zymogen peptide and nonfunctional folded peptidase without the need to use external enzymes to remove, often incompletely, the resulting fusion peptide. This technique was used to prepare the aspartic peptidase rhizopuspepsin. His-tagged rhizopuspepsinogen was expressed, and the desired protein was isolated as inclusion bodies and refolded. The proenzyme was purified by normal methods and then the relatively pure proenzyme was activated via intramolecular proteolysis at low pH. The propeptide and any inactive rhizopuspepsinogen were removed via affinity chromatography. This procedure yields a highly active rhizopuspepsin in 99% purity, which was demonstrated by PAGE, protein sequencing, and X-ray crystallography (1.5 A) of the isolated peptidase. A new fluorescent assay system is introduced for rhizopuspepsin, utilizing the substrate KPVSY(4-NO(3)-F)RL. The kinetics constants were K(m) = 3.4 microM +/- 0.31 and k(cat) = 55 +/- 1.0 s(-1).

Effect of the 7-amino substituent on the inhibitory potency of mechanism-based isocoumarin inhibitors for porcine pancreatic and human neutrophil elastases: a 1.85-A X-ray structure of the complex between porcine pancreatic elastase and 7-[(N-tosylphenylalanyl)amino]-4-chloro-3- methoxyisocoumarin

A series of new acyl, urea, and carbonate derivatives of 7-amino-4-chloro-3-methoxyisocoumarin were synthesized and evaluated as irreversible inhibitors of human neutrophil elastase (HNE) and porcine pancreatic elastase (PPE). Inhibition of HNE is directly related to the hydrophobicity of the substituent on the 7-amino group. The N-Tos-Phe derivative (19) is the best HNE inhibitor with a second-order rate constant kobs/[I] = 200,000 M-1 s-1. The closest analogue in this series, the 3,3-diphenylpropionyl derivative 5, had a kobs/[I] = 130,000 M-1 s-1 with HNE. In contrast to the Tos-Phe derivative 19, phenylacetyl derivative 2 and carbonates 22 and 25 gave extremely stable enzyme-inhibitor complexes with deacylation half-lives longer than 48 h with both elastases. N-Phenylurea derivative 25 was the best inhibitor for PPE with a second-order rate constant kobs/[I] = 7300 M-1 s-1. The crystal structure of a complex of PPE with N-tosyl-Phe derivative 19 was determined at 1.85-A resolution and refined to a final R factor of 16.9%. The isocoumarin forms an acyl enzyme with Ser-195, while His-57 is near the inhibitor, but not covalently linked. The Tos-Phe makes a few hydrophobic contacts with the S' subsites of PPE, but appears to be interacting primarily with itself in the PPE structure. This region of HNE is more hydrophobic and modeling indicates that the inhibitor would probably make additional contacts with the enzyme.