Effects of protein binding on the biodistribution of PEGylated PLGA nanoparticles post oral administration

The surface of nanoparticles is often functionalised with polymeric surfactants, in order to increase systemic circulation time. This has been investigated mainly for intravenously administered nanoparticles. This study aims to elucidate the effect of surface coating with various concentrations of polymeric surfactants (PEG and Pluronics F127) on the in vitro protein binding as well as the tissue biodistribution, post oral administration, of PLGA nanoparticles. The in vitro protein binding varied depending on the polymeric surfactant used. However, in vivo, 1% PEG and 1% Pluronics F127 coated particles presented similar biodistribution profiles in various tissues over seven days. Furthermore, the percentage of PEG and Pluronics coated particles detected in plasma was higher than that of uncoated PLGA particles, indicating that systemic circulation time can also be increased with oral formulations. The difference in the in vitro protein binding as a result of the different poloxamers used versus similar in vivo profiles of these particles indicates that in vitro observations for nanoparticles cannot represent or be correlated to the in vivo behaviour of the nanoparticles. Our results therefore suggest that more studies have to be conducted for oral formulations to give a better understanding of the kinetics of the particles.     

Phenotypic and genotypic characterization of dengue virus isolates differentiates dengue fever and dengue hemorrhagic fever from dengue shock syndrome

Dengue viruses (DENV) cause 50-100 million cases of acute febrile disease every year, including 500,000 reported cases of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Viral factors have been proposed to influence the severity of the disease, but markers of virulence have never been identified on DENV. Three DENV serotype-1 isolates from the 2007 epidemic in Cambodia that are derived from patients experiencing the various clinical forms of dengue were characterized both phenotypically and genetically. Phenotypic characteristics in vitro, based on replication kinetics in different cell lines and apoptosis response, grouped isolates from DF and DHF patients together, whereas the virus isolate from a DSS patient showed unique features: a lower level of replication in mammalian cells and extensive apoptosis in mosquito cells. Genomic comparison of viruses revealed six unique amino acid residues in the membrane, envelope, and in non-structural genes in the virus isolated from the DSS patient.     

Structural basis of NR2B-selective antagonist recognition by N-methyl-D-aspartate receptors

N-Methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors endowed with unique pharmacological and functional properties. In particular, their high permeability to calcium ions confers on NMDARs a central role in triggering long term changes in synaptic strength. Under excitotoxic pathological conditions, such as those occurring during brain trauma, stroke, or Parkinson's or Huntington's diseases, calcium influx through NMDAR channels can also lead to neuronal injury. This argues for the use of NMDAR antagonists as potential therapeutic agents. To date, the most promising NMDAR antagonists are ifenprodil and derivatives, compounds that act as noncompetitive inhibitors selective for NMDARs containing the NR2B subunit. Recent studies have identified the large N-terminal domain (NTD) of NR2B as the region controlling ifenprodil sensitivity of NMDARs. We present here a detailed characterization of the ifenprodil binding site using both experimental and computational approaches. 3D homology modeling reveals that ifenprodil fits well in a closed cleft conformation of the NRB NTD; however, ifenprodil can adopt either of two possible binding orientations of opposite direction. By studying the effects of cleft mutations, we show that only the orientation in which the phenyl moiety points deep toward the NTD hinge is functionally relevant. Moreover, based on our model, we identify novel NTD NR2B residues that are crucial for conferring ifenprodil sensitivity and provide functional evidence that these residues directly interact with the ifenprodil molecule. This work provides a general insight into the origin of the subunit-selectivity of NMDAR noncompetitive antagonists and offer clues for the discovery of novel NR2B-selective antagonists.     

Impaired Emotional Facial Expression Recognition in Alcohol Dependence: Do These Deficits Persist With Midterm Abstinence?

BACKGROUND: Emotional facial expression (EFE) decoding has been repetitively shown to be impaired in alcoholic inpatients. The present study aimed to replicate and extend previous findings on EFE recognition deficits in alcoholism. METHODS: Alcoholic and control participants' performances were compared on an EFE decoding task with a transversal and a longitudinal design. More specifically, 49 alcoholic individuals were recruited at a long-stay postdetoxification treatment center at the third or fourth week of their detoxification process. Twenty-two of them [abstinent alcoholic participants (AA)] were met at the end of their hospitalization process, 2 months later. The 27 remaining patients [dropping alcoholic participants(AD)] dropped out from treatment before the second meeting. A control group (C) of 22 participants was constituted, and assessed twice with the same average time as AA between the 2 assessments. The 3 groups were similar regarding age, sex, and education level. Participants were presented at both times with an EFE decoding test consisting of 16 photographs depicting EFE of happiness, anger, disgust, and sadness. RESULTS: The results corroborated previous findings highlighting more EFE decoding deficits in alcoholic participants compared with control participants, with no improvement after 3 months of abstinence. Transversal analyses further evidenced more EFE decoding difficulties in AD than in AA compared with controls. CONCLUSIONS: EFE decoding deficits in alcoholism persist with midterm abstinence. Alcoholic patients who dropped from treatment had the worst EFE decoding performance at baseline. Emotional facial expression decoding deficit could have a prognostic value in alcohol dependence.     

The Lille model: a new tool for therapeutic strategy in patients with severe alcoholic hepatitis treated with steroids

Early identification of patients with severe (discriminant function > or = 32) alcoholic hepatitis (AH) not responding to corticosteroids is crucial. We generated a specific prognostic model (Lille model) to identify candidates early on for alternative therapies. Three hundred twenty patients with AH prospectively treated by corticosteroids were included in the development cohort and 118 in its validation. Baseline data and a change in bilirubin at day 7 were tested. The model was generated by logistic regression. The model combining six reproducible variables (age, renal insufficiency, albumin, prothrombin time, bilirubin, and evolution of bilirubin at day 7) was highly predictive of death at 6 months (P < 0.000001). The area under the receiver operating characteristic (AUROC) curve of the Lille model was 0.89 +/- 0.02, higher than the Child-Pugh (0.62 +/- 0.04, P < 0.00001) or Maddrey scores (0.66 +/- 0.04, P < 0.00001). In the validation cohort, its AUROC was 0.85 +/- 0.04, still higher than the other models, including MELD (0.72 +/- 0.05, P = 0.01) and Glasgow scores (0.67 +/- 0.05, P = 0.0008). Patients above the ideal cutoff of 0.45 showed a marked decrease in 6-month survival as compared with others: 25% +/- 3.8% versus 85% +/- 2.5%, P < 0.0001. This cutoff was able to identify approximately 75% of the observed deaths. Conclusion: In the largest cohort to date of patients with severe AH, we demonstrate that the term "nonresponder" can now be extended to patients with a Lille score above 0.45, which corresponds to 40% of cases. Early identification of subjects with substantial risk of death according to the Lille model will improve management of patients suffering from severe AH and will aid in the design of future studies for alternative therapies.     

Anasarca, a complication of chemotherapy with gemcitabine in two patients with pancreatic cancer

Pancreatic adenocarcinoma is the fifth most common cause of cancer-related mortality in the world. The nucleoside analogue gemcitabine is the established standard therapy for advanced disease. Rare cases of gemcitabine-associated systemic capillary leak syndrome have been reported. Here, we present two cases of capillary-leak syndrome in patients with pancreatic cancer treated with gemcitabine.     

PTEN Contributes to Profound PI3K/Akt Signaling Pathway Deregulation in Dystrophin-Deficient Dog Muscle

Duchenne muscular dystrophy is the most common and severe form of muscular dystrophy, and although the genetic basis of this disease is well defined, the overall mechanisms that define its pathogenesis remain obscure. Alterations in individual signaling pathways have been described, but little information is available regarding their putative implications in Duchenne muscular dystrophy pathogenesis. Here, we studied the status of various major signaling pathways in the Golden Retriever muscular dystrophy dog that specifically reproduces the full spectrum of human pathology. Using antibody arrays, we found that Akt1, glycogen synthase kinase-3β (GSK3β), 70-kDa ribosomal protein S6 kinase (p70S6K), extracellular signal-regulated kinases 1/2, and p38δ and p38γ kinases all exhibited decreased phosphorylation in muscle from a 4-month-old animal with Golden Retriever muscular dystrophy, revealing a deep alteration of the phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase pathways. Immunohistochemistry analysis revealed the presence of muscle fibers exhibiting a cytosolic accumulation of Akt1, GSK3β, and phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase (PTEN), an enzyme counteracting PI3K-mediated Akt activation. Enzymatic assays established that these alterations in phosphorylation and expression levels were associated with decreased Akt and increased GSK3β and PTEN activities. PTEN/GSK3β-positive fibers were also observed in muscle sections from 3- and 36-month-old animals, indicating long-term PI3K/Akt pathway alteration. Collectively, our data suggest that increased PTEN expression and activity play a central role in PI3K/Akt/GSK3β and p70S6K pathway modulation, which could exacerbate the consequences of dystrophin deficiency.Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disorder that affects 1 newborn boy in 3500. This recessive disease is caused by mutations in the dystrophin gene, resulting in total lack of the protein,^1,2,3 and is characterized by severe degeneration of muscle fibers, progressive paralysis, and death. Dystrophin is located under the sarcolemma of muscle fibers, and is associated with a complex comprising several integral, peripheral membrane and cytoplasmic proteins: the dystrophin-glycoprotein complex (DGC).^4,5,6,7 By providing a strong physical link between the cytoskeleton network and the extracellular matrix, the DGC ensures the integrity of skeletal muscle fibers. In the absence of dystrophin, the complex is destabilized and this integrity is lost.^5,8 However, the impaired structural role of the DGC alone may not be sufficient to account for the massive degenerative process observed in DMD muscles. Numerous observations suggest that signaling pathway alterations may also participate in DMD pathogenesis.Dystrophin and various DGC proteins have been demonstrated to interact with a number of signaling proteins, including growth factor receptor-bound protein 2,⁹ neuronal nitric oxide synthase,¹⁰ calmodulin,¹¹ focal adhesion kinase,¹² and caveolin-3.^13,14,15 Moreover, studies of the X chromosome-linked muscular dystrophy (mdx) mouse¹⁶ revealed modulations in mitogen-activated protein kinase (MAPK) signaling cascades, as dystrophic animals exhibited increased phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2)^17,18 and c-jun N-terminal kinases 1 and 2 (JNK1/2),^19,20,21 and decreased phosphorylation of p38.¹⁸ Also, the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway has been shown to be affected in the mdx mouse, with increased synthesis and phosphorylation of Akt.^22,23In addition to the limited information related to the origin of signal perturbations in dystrophic muscle, almost no information is available regarding signaling pathways in clinically relevant animal models or human tissue samples.²³ It is noteworthy that the mdx mouse model of DMD is characterized by successive degeneration/regeneration processes, but does not exhibit the progressive muscle wasting and accumulation of connective tissue observed during the development of the human disease.^24,25,26 The Golden Retriever muscular dystrophy (GRMD) dog, characterized by rapidly progressive clinical dysfunction, severe muscle weakness, and abundant fiber necrosis, displays a disease progression that is far more similar to human DMD.^27,28In this study, we used antibody arrays to assess the global phosphorylation status of key proteins of the PI3K/Akt and MAPK signaling pathways in skeletal muscles of 4-month-old healthy and GRMD dogs. Our data indicated that Akt1, glycogen synthase kinase-3β (GSK3β) and p70S6K, as well as ERK1/2 and p38δ and γ kinases all displayed a decreased phosphorylation level in GRMD muscle. Western immunoblot, immunohistochemistry analysis, and enzymatic assays allowed us to confirm these results and demonstrated that they were associated with a reduction in Akt activity and with enhanced GSK3β expression and activity. Analysis of key enzymes involved in Akt regulation revealed that phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase (PTEN) was present at a much higher level and was more active in GRMD muscle. Moreover, immunohistochemistry analysis showed that all of the GSK3β-positive fibers observed in GRMD muscle sections exhibited a strong cytosolic labeling of PTEN, suggesting that the accumulation of the phosphatase could play a central role in PI3K/Akt signaling pathway deregulation. The observation of PTEN/GSK3β-positive fibers in muscle sections from 3- and 36-month-old GRMD dogs further demonstrated that both the early and late stages of the disease share deregulation of the pathway. Collectively, our findings highly suggest that alterations in PTEN exist in GRMD muscle, which leads to long-term and deep modulation of the PI3K/Akt signaling pathway.     

Joint-specific disruption of control during arm movements in Parkinson’s disease

The leading joint hypothesis (LJH) suggests distinct types of control (leading and subordinate) at different joints during multi-joint movements. Taking into account specific features of movements in Parkinson’s disease (PD), the LJH predicts distinct effect of PD on control of leading and subordinate joints: impaired interaction torque (INT) regulation should be emphasized at the subordinate joints, and impaired generation of muscle torque (MUS) magnitude should be more pronounced at the leading joint. This prediction was tested by studying three tasks of horizontal shoulder-elbow movements in PD patients and age-matched controls: cyclic line drawing, cyclic point-to-point, and discrete pointing movements. Each task included movements in different directions, providing both shoulder-lead and elbow-lead control patterns. Torque analysis supported the prediction, specifically for Tasks 2 and 3 in which movement targets were chosen to emphasize the shoulder- and elbow-lead control patterns. Patients did not exploit INT for motion generation as successfully as controls did, but only at the subordinate joint. Underproduction of MUS by PD patients was more apparent at the leading than subordinate joint. The results support joint-specific effect of PD on movement control. They also suggest that dyscoordination of joint motions in PD stems predominantly from impaired control of subordinate joints, while bradykinesia is associated more with control of the leading than subordinate joint. Possible contribution of the revealed impairments in joint control to some other movement features in PD is discussed. The study demonstrates the efficiency of the LJH application for revealing changes in joint control caused by motor disorders.