Group III and subtype 4 metabotropic glutamate receptor agonists: discovery and pathophysiological applications in Parkinson's disease

Restoring the balance between excitatory and inhibitory circuits in the basal ganglia, following the loss of dopaminergic (DA) neurons of the substantia nigra pars compacta, represents a major challenge to treat patients affected by Parkinson's disease (PD). The imbalanced situation in favor of excitation in the disease state may also accelerate excitotoxic processes, thereby representing a potential target for neuroprotective therapies. Reducing the excitatory action of glutamate, the major excitatory neurotransmitter in the basal ganglia, should lead to symptomatic improvement for PD patients and may promote the survival of DA neurons. Recent studies have focused on the modulatory action of metabotropic glutamate (mGlu) receptors on neurodegenerative diseases including PD. Group III mGlu receptors, including subtypes 4, 7 and 8, are largely expressed in the basal ganglia. Recent studies highlight the use of selective mGlu4 receptor positive allosteric modulators (PAMs) for the treatment of PD. Here we review the effects of newly-designed group-III orthosteric agonists on neuroprotection, neurorestoration and reduction of l-DOPA induced dyskinesia in animal models of PD. The combination of orthosteric mGlu4 receptor selective agonists with PAMs may open new avenues for the symptomatic treatment of PD. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.

Olives and olive oil: diet and health impacts

Abstract

The Mediterranean diet is a compilation of the nutritional and dietary habits of the countries of the Mediterranean Basin. The principal product of the Mediterranean Basin is virgin olive oil, which is obtained from different varieties of olives that confer their individual nutritional and organoleptic properties. Virgin olive oil is rich in monounsaturated fatty acids (MUFAs; mainly oleic acid), but contains other minor compounds (mainly polyphenols), both of which have been demonstrated to have benefits on human health. Epidemiological studies, long- and short-term intervention studies, and postprandial studies have found associations between a virgin-olive-oil-rich diet and decreased cardiovascular risk factors, stroke incidence and type-2 diabetes. Lowered plasma low-density lipoprotein (LDL)-cholesterol levels, haemostatic factors and inflammation markers, as well as improved endothelial function and insulin sensitivity, are common outcomes of such studies. Furthermore, these studies showed additional protection against oxidative stress, LDL oxidation and thrombosis, which were attributed to minor compounds in virgin olive oil.

Inhibiting rotavirus infection by membrane-impermeant thiol/disulfide exchange blockers and antibodies against protein disulfide isomerase

OBJECTIVES

Determining the effect of membrane-impermeant thiol/disulfide exchange inhibitors on rhesus rotavirus infectivity in MA104 cells and investigating protein disulfide isomerase (PDI) as a potential target for these inhibitors.

METHODS

Cells were treated with DTNB [5,5-dithio-bis-(2-nitrobenzoic acid)], bacitracin or anti-PDI antibodies and then infected with virus. Triple-layered particles (TLPs) were also pretreated with inhibitors before inoculation. The effects of these inhibitors on α-sarcin co-entry, virus binding to cells and PDI-TLP interaction were also examined. FACS analysis, cell-surface protein biotin-labeling, lipid-raft isolation and ELISA were performed to determine cell-surface PDI expression.

RESULTS

Infectivity became reduced by 50% when cells or TLPs were treated with 1 or 6 mM DTNB, respectively; infectivity became reduced by 50% by 20 mM bacitracin treatment of cells whereas TLPs were insensitive to bacitracin treatment; anti-PDI antibodies decreased viral infectivity by about 45%. The presence of DTNB (2.5 mM) or bacitracin (20 mM) was unable to prevent virus binding to cells and rotavirus-induced α-sarcin co-entry.

CONCLUSIONS

It was concluded that thiol/disulfide exchange was involved in rotavirus entry process and that cell-surface PDI was at least a potential target for DTNB and bacitracin-induced infectivity inhibition.

Agminated, eruptive pyogenic granuloma-like lesions developing over congenital vascular stains

We report three infants who developed agminated pyogenic granulomas over congenital vascular malformations, all of which had an aggressive growth pattern. There were no precipitating events such as laser therapy or surgery. Lesions were excised.

Antiparkinsonian action of a selective group III mGlu receptor agonist is associated with reversal of subthalamonigral overactivity

Activation of group III metabotropic glutamate (mGlu) receptors has been recently highlighted as a potential approach in the treatment of Parkinson's disease (PD). This study evaluates the antiparkinsonian action of systemic administration of the broad-spectrum agonist of group III mGlu receptors, 1-aminocyclopentane-1,3,4-tricarboxylic acid (ACPT-I), and investigates its site of action within the basal ganglia circuitry. Acute injection of ACPT-I reverses haloperidol-induced catalepsy, an index of akinesia in rodents. In a rat model of early PD based on partial bilateral nigrostriatal lesions, chronic (2weeks) administration of ACPT-I is required to efficiently alleviate the akinetic deficit evidenced in a reaction time task. This treatment counteracts the post-lesional increases in the gene expression of cytochrome oxidase subunit I, a metabolic marker of neuronal activity, in the overall subthalamic nucleus and in the lateral motor part of the substantia nigra pars reticulata (SNr) but has no effect in the globus pallidus. Paradoxically, ACPT-I administration in sham animals impairs performance and induces overexpression of cytochrome oxidase subunit I mRNA in the lateral SNr, and has no effect in the subthalamic nucleus or globus pallidus. Altogether, our results provide new evidence for the antiparkinsonian efficiency of group III mGlu receptor agonism, point to the regulation of the overactive subthalamo-nigral connection as a main site of action in an early stage of PD and underline the complex interplay between these receptors and the dopaminergic system to regulate basal ganglia function in control and PD conditions.

Optical fiber refractometers based on indium tin oxide coatings fabricated by sputtering

This Letter presents the fabrication of optical fiber refractometers based on indium tin oxide (ITO) coatings deposited by sputtering with response in the visible region. ITO thin films have been sputtered by means of a rotating mechanism that enables the fabrication of smooth and homogeneous coatings onto the optical fiber core. The ITO coating acts as a resonance supporting layer. This permits us to couple light from the waveguide to the ITO-coating/external medium region at specific wavelength ranges. The device is sensitive to external medium refractive index, which allows its utilization as a refractometer. The sensitivity is dependent on the coating thickness, ranging from 523.21 to 1221 nm/refractive index unit in the explored sensors. The sensor development process is time effective compared to other techniques such as dip coating or layer-by-layer self-assembly, which is interesting in terms of mass production.

P2-10-04: 3D Mapping of Total Choline in Human Breast Cancer Using High-Speed MR Spectroscopic Imaging at 3T: A Feasibility Study

PURPOSE: To assess the feasibility of quantitative high-speed MR spectroscopic imaging (MRSI) of total Choline (tCho) as an adjunct to dynamic-contrast enhanced (DCE) MRI to improve lesion characterization and monitor treatment response in patients undergoing neoadjuvant chemotherapy.

METHOD AND MATERIALS: Seven patients with biopsy-confirmed, infiltrating ductal carcinoma were studied using a clinical 3T MR scanner (Siemens Medical Solutions, Erlangen, Germany) equipped with 8- and 16-channel breast array (Hologic Inc., Bedford, MA). Measurements were performed using PRESS prelocalized 3D Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI) using TR/TE=2000ms/135ms, matrix size up to 32×16x8, voxel size=1cc, and total acquisition time of 10 minutes (including water reference scan). Additional data were collected at TE 60 ms to enhance sensitivity for detecting tCho and J-coupled resonances. TE-averaging (8 steps, ΔTE: 2.5 ms) was employed to minimize gradient sideband artifacts. Quantification of tCho in reference to tissue water was performed using spectral fitting and relaxation correction.

RESULTS: Strongly elevated tCho with maximum concentration ranging from 0.3 to 4.1 mmol/kg was measured in five patients with single and multi-centric enhancing lesions larger than 2 cc volume (Table 1). The measured tCho concentration in Grade 3 tumors was higher than in lower grade untreated and treated tumors. Strong decreases in tCho concentration were measured in 2 patients undergoing neoadjuvant therapy in a follow-up scan. At short TE an additional resonance was detected that was elevated in enhancing lesions and tentatively assigned to Taurine. Two patients had lesions smaller than 2 cc with surgical clips in which tCho was not detectable due to line broadening. MRSI data sets were preferentially collected before contrast injection, since it increased spectral line width by up to 50%.

CONCLUSION: This study demonstrates feasibility of quantitatively mapping tCho in invasive breast carcinoma using high-speed MRSI. The long-term goals are to utilize high-speed MRSI as an early predictor of treatment failure in women undergoing neoadjuvant therapy (i.e. chemotherapy, endocrine therapy or biologic therapy) for breast cancer and to develop an improved screening protocol for high-risk patients. Grant support: 1RC1EB010617-01

A Bayesian approach to analyze energy balance data from lactating dairy cows

The objective of the present investigation was to develop a Bayesian framework for updating and integrating covariate information into key parameters of metabolizable energy (ME) systems for dairy cows. The study addressed specifically the effects of genetic improvements and feed quality on key parameters in current ME systems. These are net and metabolizable energy for maintenance (NE(M) and ME(M), respectively), efficiency of utilization of ME for milk production (k(L)) and growth (k(G)), and efficiency of utilization of body stores for milk production (k(T)). Data were collated from 38 studies, yielding 701 individual cow observations on milk energy, ME intake, and tissue gain and loss. A function based on a linear relationship between milk energy and ME intake and correcting for tissue energy loss or gain served as the basis of a full Bayesian hierarchical model. The within-study variability was modeled by a Student t-distribution and the between-study variability in the structural parameters was modeled by a multivariate normal distribution. A meaningful relationship between genetic improvements in milk production and the key parameters could not be established. The parameter k(L) was linearly related to feed metabolizability, and the slope predicted a 0.010 (-0.0004; 0.0210) change per 0.1-unit change in metabolizability. The effect of metabolizability on k(L) was smaller than assumed in present feed evaluation systems and its significance was dependent on collection of studies included in the analysis. Three sets of population estimates (with 95% credible interval in parentheses) were generated, reflecting different degrees of prior belief: (1) Noninformative priors yielded 0.28 (0.23; 0.33) MJ/(kg(0.75)d), 0.55 (0.51; 0.58), 0.86 (0.81; 0.93) and 0.66 (0.58; 0.75), for NE(M), k(L), k(G), and k(T), respectively; (2) Introducing an informative prior that was derived from a fasting metabolism study served to combine the most recent information on energy metabolism in modern dairy cows. The new estimates of NE(M), k(L), k(G) and k(T) were 0.34 (0.28; 0.39) MJ/(kg(0.75)d), 0.58 (0.54; 0.62), 0.89 (0.85; 0.95), and 0.69 (0.60; 0.79), respectively; (3) finally, all informative priors were used that were established from literature, yielding estimates for NE(M), k(L), k(G), and k(T) of 0.29 (0.11; 0.46) MJ/(kg(0.75)d), 0.60 (0.54; 0.70), 0.70 (0.50; 0.88), and 0.80 (0.67; 0.97), respectively. Bayesian methods are especially applicable in meta-analytical studies as information can enter at various stages in the hierarchical model.

Modeling the efficiency of phosphorus utilization in growing pigs

Microbial phytase has been used to reduce P excretion from swine to mitigate environmental pollution. The objective of the study was to quantify the effect of feeding a low-P phytase-supplemented diet on growth and P utilization in growing pigs using mathematical models. A total of 20 weaned piglets (BW = 6.5 kg) housed in metabolism cages were randomly assigned to a standard diet (STD) or P-amended diet containing reduced P content and supplemented with phytase (AMN) with 10 pigs/diet. Body weight and feed consumption were recorded weekly so complete growth and cumulative P intake (cPI) curves could be modeled. A function with fixed point of inflexion (Gompertz) and a variable point of inflexion (generalized Michaelis-Menten) were considered in determining bioequivalence by analyzing BW vs. age relationships, whereas the monomolecular function was used to describe BW vs. cPI. All functions were incorporated into a nonlinear mixed effects model, and a first-order autoregressive correlation structure was implemented to take into account repeated measures. There was no difference between the 2 groups in final BW when the Gompertz equation was fitted (176 vs. 178 kg with SE of 7 kg for the STD and AMN, respectively) or the rate parameter (0.0140 vs. 0.0139 with SE of 0.0004 for the STD and AMN, respectively). The generalized Michaelis-Menten equation also showed a similar trend. When BW was expressed as a function of cPI the derivative with respect to cPI represented P efficiency, so it was possible to analyze the expected difference of the 2 diets in using P for BW gain and express it as a continuous function of cPI. The analysis showed through the entire growth period the difference in P efficiency was different from zero. On average, 56 g of supplemented inorganic P was consumed by a pig fed the AMN to reach market weight. In contrast, 309 g of supplemented inorganic P was consumed by the group fed the STD to reach similar BW. It would depend on other factors, but feeding pigs the AMN can result in economic benefit. Pigs fed the AMN excreted 19% less P compared with those fed the STD. In conclusion, nonlinear mixed model analysis (with repeated measures) was suitable for growth and efficiency analysis and showed that pigs fed the AMN consumed less than 20% of the inorganic P and performed as well as those fed the traditional inorganic P supplemented diet. The implications for mitigating P pollution, especially in areas where P loading is already problematic, are substantial.

Natural killer-dendritic cell interaction in lymphocyte responses in hypersensitivity reactions to betalactams

BACKGROUND

Betalactams are the commonest cause of allergic reactions mediated by either IgE or T lymphocytes in which innate and adaptive immune systems mediate the earlier stages of immunological responses. One of the links between these systems is related to the interaction between natural killer (NK) and dendritic cells (DC). We have evaluated the role of NK cells and NK-DC interaction in the immunopathological mechanisms of nonimmediate reactions to betalactams.

METHODS

Patients allergic to amoxicillin (AX) (N = 17) and tolerant controls (N = 13) were included. Changes in phenotype (CD69, IFNγ, perforin, and granzyme B) in AX-stimulated NK cells, the cytotoxic activity on mature or immature DC (imDC), and the proliferation and phenotype of NK lymphocytes after culture with AX and DC were determined by flow cytometry.

RESULTS

Amoxicillin induced activation and increases of perforin and granzyme B (P = 0.007 and P = 0.041 respectively) but not IFNγ production in NK cells from patients. In NK subpopulations, AX induced a significant enhancement of perforin and granzyme B in CD56(dim) (P = 0.005 and P = 0.002 respectively) and of IFNγ in CD56(bright) (P = 0.001). The cytotoxic phenotype was demonstrated by an increase of annexin V only in imDC (P < 0.001). Amoxicillin also induced an increased NK proliferation with different patterns, cytotoxic or proinflammatory, depending on the presence of imDC or mature DC, respectively. No differences were observed in NK cells from tolerant controls.

CONCLUSION

These data could demonstrate the involvement of NK cells in the immunopathological mechanisms of nonimmediate allergic reactions to AX, showing that both the innate and adaptive immune systems are involved and crosstalk, producing amplification of the harmful effects observed in these drug reactions.

The MIT D-lab electricity-free PortaTherm™ incubator for remote testing with the QuantiFERON®-TB Gold In-Tube assay

BACKGROUND

Use of the QuantiFERON®-TB Gold In-Tube assay (QFT-GIT) in remote areas is limited by the need to incubate blood samples within 12 h of collection. PortaTherm™ is a portable, electricity-free, phase-change incubator previously used for field collection of microbiological samples.

OBJECTIVE

To determine whether the PortaTherm can be used for the reliable incubation of QFT-GIT samples, thus enabling QFT-GIT use in settings distant from laboratory facilities.

METHODS

In a prospective comparative study in Peru, blood samples were collected from 50 participants and processed in three parallel QFT-GIT tests per participant; two were incubated in a conventional incubator; the third was incubated in the PortaTherm.

RESULTS

All 150 QFT-GIT tests gave definitive results, and for 46 of the 50 participants all three tests were concordant, eight of which were positive. Four participants had one discordant result: two due to discordance of a conventional incubator QFT-GIT result, and two due to discordant PortaTherm QFT-GIT results.

CONCLUSION

The QFT-GIT inter-incubator variability between the PortaTherm and conventional incubator was no greater than the intra-incubator variability for the conventional incubator, indicating that the PortaTherm is a suitable tool for incubating QFT-GIT whole blood samples in remote settings where access to a laboratory or electricity is limited.

Role of effector cells (CCR7(-)CD27(-)) and effector-memory cells (CCR7(-)CD27(+)) in drug-induced maculopapular exanthema

Maculopapular exanthema (MPE) induced by drugs is a T-cell mediated reaction and effector cells may play an important role in its development. We assessed the effector and cutaneous homing phenotype in peripheral blood cells from allergic patients after drug stimulation. This study included 10 patients and 10 controls. The effector phenotype (CCR7(-)CD27(+/-)), chemokine receptors (CCR4 and CCR10), and activation (CD25(low)) and regulatory markers (CD25(high)) were measured by flow cytometry in both peripheral blood mononuclear cells (PBMCs) and CD4-T-lymphocytes. Proliferation was determined by 5-(-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE) assay and the migratory capacity by a chemotaxis assay using CCL17 and CCL27. Compared to controls, CCR7(-)CD27(-) cells were increased in patients without (p=0.003) and with drug stimulation (p less than 0.001) and had significantly higher proliferation (p=0.010). CCR10 expression was increased in patients after drug stimulation in total and memory CD27(+) T-cells. Lymphocyte migration with CCL27 was higher in patients with drug stimulation (p=0.048), with a decrease in CCR7(-)CD27(-) (p less than 0.0001) and an increase in CCR7(-)CD27(+) (p=0.017). In patients, CD4-T-lymphocytes were significantly activated after drug stimulation (p less than 0.001). In conclusion, we show that effector memory CD4(+) T-cells (CCR7(-)CD27(+)) respond specifically to the drug responsible for MPE and confirm previous data about the involvement of CCR10 in cell trafficking to the skin.