A Polyrotaxane-based pH-labile Drug Delivery System

A novel polyrotaxane (PR)-based triblock copolymer was exploited as polymeric carrier for doxorubicin (DOX). A sample holding a feed molar ratio of Pluronic F127 to β-CD to poly(ethylene glycol) methyl ether methacrylate (PEGMA) equal to 1:30:20 was synthesized via the in situ atom transfer radical polymerization (ATRP) and then conjugated with DOX using pH sensitive hydrazone linker. The resulting PR-DOX conjugates enabled to self-assemble into nano-particles of about 70 nm in diameter in aqueous solution as evidenced by TEM. The release of DOX was varied from 10 % to 37 % over 72 h at physiological and acidic pH, respectively. The PR-based triblock copolymer without DOX conjugation showed almost non toxicity, while these nano-particles with DOX conjugation presented increased toxicity

Elevated interleukin-8 enhances prefrontal synaptic transmission in mice with persistent inflammatory pain

<p>Abstract</p> <p>Background</p> <p>Interleukin-8 (IL-8) is known for its roles in inflammation and plays critical roles in the development of pain. Its expression increases in the brain after peripheral inflammation. Prefrontal cortex, including the anterior cingulate cortex (ACC), is a forebrain structure known for its roles in pain transmission and modulation. Painful stimuli potentiate the prefrontal synaptic transmission, however, little is known about the expression of IL-8 and its role in the enhanced ACC synaptic transmission in animals with persistent inflammatory pain.</p> <p>Findings</p> <p>In the present study, we examined IL-8 expression in the ACC, somatosensory cortex (SSC), and the dorsal horn of lumbar spinal cord following hind-paw administration of complete Freund's adjuvant (CFA) in mice and its effects on the ACC synaptic transmission. Quantification of IL-8 at protein level (by ELISA) revealed enhanced expression in the ACC and spinal cord during the chronic phases of CFA-induced peripheral inflammation. In vitro whole-cell patch-clamp recordings revealed that IL-8 significantly enhanced synaptic transmission through increased probability of neurotransmitter release in the ACC slice. ACC local infusion of repertaxin, a non-competitive allosteric blocker of IL-8 receptors, notably prolonged the paw withdrawal latency to thermal radian heat stimuli bilaterally in mice.</p> <p>Conclusions</p> <p>Our findings suggest that up-regulation of IL-8 in the ACC partly attributable to the enhanced prefrontal synaptic transmission in the mice with persistent inflammatory pain.</p

Microglia Prevent Beta-Amyloid Plaque Formation in the Early Stage of an Alzheimer\u27s Disease Mouse Model with Suppression of Glymphatic Clearance

BACKGROUND: Soluble beta-amyloid (Aβ) can be cleared from the brain through various mechanisms including enzymatic degradation, glial cell phagocytosis, transport across the blood-brain barrier, and glymphatic clearance. However, the relative contribution of each clearance system and their compensatory effects in delaying the pathological process of Alzheimer\u27s disease (AD) are currently unknown. METHODS: Fluorescent trace, immunofluorescence, and Western blot analyses were performed to compare glymphatic clearance ability and Aβ accumulation among 3-month-old APP695/PS1-dE9 transgenic (APP/PS1) mice, wild-type mice, aquaporin 4 knock out (AQP4−/−) mice, and AQP4−/−/APP/PS1 mice. The consequence of selectively eliminating microglial cells, or downregulating apolipoprotein E (apoE) expression, on Aβ burden, was also investigated in the frontal cortex of AQP4−/−/APP/PS1 mice and APP/PS1 mice. RESULTS: AQP4 deletion in APP/PS1 mice significantly exaggerated glymphatic clearance dysfunction, and intraneuronal accumulation of Aβ and apoE, although it did not lead to Aβ plaque deposition. Notably, microglia, but not astrocytes, increased activation and phagocytosis of Aβ in the cerebral cortex of AQP4−/−/APP/PS1 mice, compared with APP/PS1 mice. Selectively eliminating microglia in the frontal cortex via local injection of clodronate liposomes resulted in deposition of Aβ plaques in AQP4−/−/APP/PS1 mice, but not APP/PS1 mice. Moreover, knockdown of apoE reduced intraneuronal Aβ levels in both APP/PS1 mice and AQP4−/−/APP/PS1 mice, indicating an inhibitory effect of apoE on Aβ clearance. CONCLUSION: The above results suggest that the glymphatic system mediated Aβ and apoE clearance and microglia mediated Aβ degradation synergistically prevent Aβ plague formation in the early stages of the AD mouse model. Protecting one or both of them might be beneficial to delaying the onset of AD

Relationship between low-density lipoprotein levels on admission and 1-year outcome in patients with acute ST-segment-elevation myocardial infarction

AbstractThis study assessed the relationship between low-density lipoprotein cholesterol (LDL-C) levels on admission and the incidence of major adverse cardiovascular events (MACE) in patients with acute ST-segment-elevation myocardial infarction (ASTEMI). Patients with ASTEMI who had a lipid profile tested within 24 hours of symptom onset were enrolled. They were stratified into high and low LDL-C groups according to whether their LDL-C was above (n = 501) or below (n = 575) the median level, respectively. The incidence of MACE, cardiovascular death, non-fatal MI, revascularization, and stroke was compared between the groups at 1 month, 6 months, and 1 year. Survival analysis and Cox proportional hazard analysis were performed. In-hospital use of beta blockers was better in the high than in the low LDL-C group (76.6% vs. 69.7%, p = 0.01). Statin use was significantly higher in the high than in the low LDL-C group during follow-up (86.8% vs. 80.0%, p = 0.003 at1 month; 71.6% vs. 62.4%, p = 0.002 at 6 months; 67.8% vs. 61.2%, p = 0.03 at 1 year). The incidence of MACE on follow-up at 1 month was higher in the low than in the high LDL-C group (12.0% vs. 8.1%, p = 0.04). At 1 year, survival was not significantly different between the groups. Cox proportional hazards analysis indicated that the incidence of MACE was significantly associated with hypertension, current smoking, high-density lipoprotein cholesterol (HDL-C), in-hospital use of beta blockers, and statin use on follow-up (p < 0.01). LDL-C levels on admission in patients with ASTEMI had no significant effect on the 6-month and 1-year incidence of MACE, but the incidence of MACE was significantly higher in the low LDL-C group at 1 month. It would be relevant to further investigate the HDL-C level on admission, in-hospital use of beta blockers, and statin use during follow-up in relation to MACE

Reversible and time-dependent inhibition of CYP3A4-mediated nifedipine oxidation by noscapine

Substrate-dependent inhibition of CYP3A4 might influence the extrapolation of drug interactions from the in vitro to in vivo situation. The aim of the present study is to investigate reversible and time-dependent inhibition of CYP3A4-mediated nifedipine oxidation by noscapine. Furthermore, in vitroin vivo extrapolation (IVIVE) was performed using in vitro parameters. The results showed that CYP3A4- mediated nifedipine oxidation activity was strongly inhibited with an IC50 of 25.7 ± 5.4 μM. Kinetic analysis showed that inhibition of CYP3A4-mediated nifedipine oxidation by noscapine was best fit to a noncompetitive manner with Ki value of 10.9 μM. IC50 shift experiment showed that IC50 was significantly decreased from 25.7 ± 5.4 μM to 0.34 ± 0.07 μM after pre-incubation with noscapine for 30 min, which indicated that time-dependent inhibition existed for inhibition of CYP3A4 by noscapine. The AUC of (R)- warfarin was predicted to increase by 0.5 % using Cmax or 0.2 % using unbound Cmax with reversible inhibition prediction equation, while the AUC of (R)-warfarin was estimated to increase by 23.1 % using Cmax or 10.4 % using unbound Cmax with TDI prediction equation. Inhibition of CYP3A4 by noscapine showed substrate-dependent inhibition behaviour. However, the results obtained from IVIVE are very similar using testosterone or nifedipine as probe substrates.Colegio de Farmacéuticos de la Provincia de Buenos Aire