Lipid-based Nanocarriers for siRNA Delivery: Challenges, Strategies and the Lessons Learned from the DODAX: MO Liposomal System.

The possibility of using the RNA interference (RNAi) mechanisms in gene therapy was one of the scientific breakthroughs of the last century. Despite the extraordinary therapeutic potential of this approach, the need for an efficient gene carrier is hampering the translation of the RNAi technology to the clinical setting. Although a diversity of nanocarriers has been described, liposomes continue to be one of the most attractive siRNA vehicles due to their relatively low toxicity, facilitated siRNA complexation, high transfection efficiency and enhanced pharmacokinetic properties. This review focuses on RNAi as a therapeutic approach, the challenges to its application, namely the nucleic acids' delivery process, and current strategies to improve therapeutic efficacy. Additionally, lipid-based nanocarriers are described, and lessons learned from the relation between biophysical properties and biological performance of the dioctadecyldimethylammonium:monoolein (DODAX: MO) system are explored. Liposomes show great potential as siRNA delivery systems, being safe nanocarriers to protect nucleic acids in circulation, extend their half-life time, target specific cells and reduce off-target effects. Nevertheless, several issues related to delivery must be overcome before RNAi therapies reach their full potential, namely target-cell specificity and endosomal escape. Understanding the relationship between biophysical properties and biological performance is an essential step in the gene therapy field.

Contact Allergy to Neem Oil.

A case of allergic contact dermatitis from neem oil is presented. Neem oil (synonyms: Melia azadirachta seed oil [INCI name], nim oil, margosa oil) is a vegetable (fixed) oil obtained from the seed of the neem tree Azadirachta indica by cold pressing. Contact allergy to neem oil has been described previously in only 3 patients. The allergen(s) is/are unknown.

Design and in vivo evaluation of solid lipid nanoparticulate systems of Olanzapine for acute phase schizophrenia treatment: Investigations on antipsychotic potential and adverse effects.

The present paper discusses the design, characterization and in vivo evaluation of glyceryl monostearate nanoparticles of Olanzapine, an atypical antipsychotic drug for acute schizophrenia treatment, during which hospitalization is mandatory and adverse effects are at its peak. The solid lipid nanoparticulate system was obtained by emulsification-ultra sonication technique wherein three factors such as solid lipid content, concentration of surfactant and drug: solid lipid ratio were selected at three different levels in order to study their influence on significant characteristic responses such as particle size, encapsulation efficiency and drug content. A Box Behnken design with 17 runs involving whole factors at three levels was employed for the study. The optimized formulation was further coated with Polysorbate 80 in order to enhance its brain targeting potential through endocytosis transport process via blood brain barrier. The designed formulations were pre-clinically tested successfully in Wistar rat model for in vivo antipsychotic efficacy (apomorphine induced psychosis) and adverse effects (weight gain study for 28days). The results obtained indicated that solid lipid nanoparticles had very narrow size distribution (151.29±3.36nm) with very high encapsulation efficiency (74.51±1.75%). Morphological studies by SEM have shown that solid lipid nanoparticles were spherical in shape with smooth surface. Olanzapine-loaded nanoparticles prepared from solid lipid, extended the release of drug for 48h, as found by the in vitro release studies. The formulations also exhibited high redispersibility after freeze-drying and stability study results demonstrated good stability, with no significant change for a period of 6months. In vivo evaluation and adverse effects studies of Olanzapine-loaded nanoparticulate systems in animal model have demonstrated an improved therapeutic efficacy than pure Olanzapine. The antipsychotic effect of drug loaded nanoparticulate systems was maintained for 48h as compared to 8h antipsychotic action of pure Olanzapine solution. The weight gain studies for 28days demonstrated a significant inhibition in weight gain for Olanzapine-loaded nanoparticulate systems as compared to the pure Olanzapine. The present research findings indicate that OLN-loaded nanoparticulate systems may be highly promising for effective delivery of Olanzapine with better efficacy and minimum adverse effects.

The Role of Endocannabinoid Signaling in Cortical Inhibitory Neuron Dysfunction in Schizophrenia.

Cannabis use has been reported to increase the risk of developing schizophrenia and to worsen symptoms of the illness. Both of these outcomes might be attributable to the disruption by cannabis of the endogenous cannabinoid system's spatiotemporal regulation of the inhibitory circuitry in the prefrontal cortex that is essential for core cognitive processes, such as working memory, which are impaired in schizophrenia. In the healthy brain, the endocannabinoid 2-arachidonylglycerol 1) is synthesized by diacylglycerol lipase in pyramidal neurons; 2) travels retrogradely to nearby inhibitory axon terminals that express the primary type 1 cannabinoid receptor (CB1R); 3) binds to CB1R, which inhibits gamma-aminobutyric acid release from the cholecystokinin-containing population of interneurons; and 4) is metabolized by either monoglyceride lipase, which is located in the inhibitory axon terminal, or by α-ß-hydrolase domain 6, which is co-localized presynaptically with diacylglycerol lipase. Investigations of the endogenous cannabinoid system in the prefrontal cortex of subjects with schizophrenia have found evidence of higher metabolism of 2-arachidonylglycerol, as well as both greater CB1R receptor binding and lower levels of CB1R messenger RNA and protein. Current views on the potential pathogenesis of these alterations, including disturbances in the development of the endogenous cannabinoid system, are discussed. In addition, how interactions between these alterations in the endocannabinoid system and those in other inhibitory neurons in the prefrontal cortex in subjects with schizophrenia might increase the liability to adverse outcomes with cannabis use is considered.

Non-Selective Cannabinoid Receptor Antagonists, Hinokiresinols Reduce Infiltration of Microglia/Macrophages into Ischemic Brain Lesions in Rat via Modulating 2-Arachidonolyglycerol-Induced Migration and Mitochondrial Activity.

Growing evidence suggests that therapeutic strategies to modulate the post-ischemic inflammatory responses are promising approaches to improve stroke outcome. Although the endocannabinoid system has been emerged as an endogenous therapeutic target to regulate inflammation after stroke insult, the downstream mechanisms and their potentials for therapeutic intervention remain controversial. Here we identified trans- and cis-hinokiresinols as novel non-selective antagonists for two G-protein-coupled cannabinoid receptors, cannabinoid receptor type 1 and type 2. The Electric Cell-substrate Impedance Sensing and Boyden chamber migration assays using primary microglial cultures revealed that both hinokiresinols significantly inhibited an endocannabinoid, 2-arachidonoylglycerol-induced migration. Hinokiresinols modulated 2-arachidonoylglycerol-induced mitochondrial bioenergetics in microglia as evidenced by inhibition of ATP turnover and reduction in respiratory capacity, thereby resulting in impaired migration activity. In rats subjected to transient middle cerebral artery occlusion (1.5-h) followed by 24-h reperfusion, post-ischemic treatment with hinokiresinols (2 and 7-h after the onset of ischemia, 10 mg/kg) significantly reduced cerebral infarct and infiltration of ED1-positive microglial/macrophage cells into cerebral ischemic lesions in vivo. Co-administration of exogenous 2-AG (1 mg/kg, i.v., single dose at 2 h after starting MCAO) abolished the protective effect of trans-hinokiresionol. These results suggest that hinokiresinols may serve as stroke treatment by targeting the endocannabinoid system. Alteration of mitochondrial bioenergetics and consequent inhibition of inflammatory cells migration may be a novel mechanism underlying anti-ischemic effects conferred by cannabinoid receptor antagonists.

Citrem modulates internal nanostructure of glyceryl monooleate dispersions and bypasses complement activation: Towards development of safe tunable intravenous lipid nanocarriers.

Lyotropic non-lamellar liquid crystalline (LLC) aqueous nanodispersions hold a great promise in drug solubilization and delivery, but these nanosystems often induce severe hemolysis and complement activation, which limit their applications for safe intravenous administration. Here, we engineer and characterize LLC aqueous nanodispersions from a binary lipid mixture consisting of 2,3-dihydroxypropyl oleate (glyceryl monooleate) and medium-chain triglycerides with tunable internal nanostructures and improved hemocompatibility controlled by citrem as stabilizer. Citrem, in a concentration-dependent manner, modulates the internal nanostructure of LLC dispersions from a biphasic H2/L2 feature to a neat L2 phase, where the latter resembles "thread-like" swollen micelles. Citrem stabilization totally overcomes hemolysis and complement activation, thus realizing the potential of the engineered LLC aqueous nanodispersions for exploitation in intravenous delivery of drugs and contrast agents. FROM THE CLINICAL EDITOR: The complement system often gets activated after intravenous injection of nano drug-carriers. This may result in detrimental systemic effects. The authors described in this article the use of citrem as a stabilizing agent and showed the ability of this agent to abolish complement activation. Hence, citrem may prove to be an important component of tunable LLC nanocarriers that may be useful in future clinical setting.

An in situ gelling liquid crystalline system based on monoglycerides and polyethylenimine for local delivery of siRNAs.

The development of delivery systems able to complex and release siRNA into the cytosol is essential for therapeutic use of siRNA. Among the delivery systems, local delivery has advantages over systemic administration. In this study, we developed and characterized non-viral carriers to deliver siRNA locally, based on polyethylenimine (PEI) as gene carrier, and a self-assembling drug delivery system that forms a gel in situ. Liquid crystalline formulations composed of monoglycerides (MO), PEI, propylene glycol (PG) and 0.1M Tris buffer pH 6.5 were developed and characterized by polarized light microscopy, Small Angle X-ray Scattering (SAXS), for their ability to form inverted type liquid crystalline phases (LC2) in contact with excess water, water absorption capacity, ability to complex with siRNA and siRNA release. In addition, gel formation in vivo was determined by subcutaneous injection of the formulations in mice. In water excess, precursor fluid formulations rapidly transformed into a viscous liquid crystalline phase. The presence of PEI influences the liquid crystalline structure of the LC2 formed and was crucial for complexing siRNA. The siRNA was released from the crystalline phase complexed with PEI. The release rate was dependent on the rate of water uptake. The formulation containing MO/PEI/PG/Tris buffer at 7.85:0.65:76.5:15 (w/w/w/w) complexed with 10 µM of siRNA, characterized as a mixture of cubic phase (diamond-type) and inverted hexagonal phase (after contact with excess water), showed sustained release for 7 days in vitro. In mice, in situ gel formation occurred after subcutaneous injection of the formulations, and the gels were degraded in 30 days. Initially a mild inflammatory process occurred in the tissue surrounding the gel; but after 14 days the tissue appeared normal. Taken together, this work demonstrates the rational development of an in situ gelling formulation for local release of siRNA.

Assessment of the effect of esterified propoxylated glycerol (EPG) on the status of fat-soluble vitamins and select water-soluble nutrients following dietary administration to humans for 8 weeks.

This double-blind, randomized, controlled study assessed the effect of esterified propoxylated glycerol (EPG) on fat-soluble vitamins and select nutrients in human subjects. For 8 weeks, 139 healthy volunteers consumed a core diet providing adequate caloric and nutrient intakes. The diet included items (spread, muffins, cookies, and biscuits) providing EPG (10, 25, and 40 g/day) vs. margarine alone (control). EPG did not significantly affect circulating retinol, α-tocopherol, or 25-OH D2, but circulating ß-carotene and phylloquinone were lower in the EPG groups, and PIVKA-II levels were higher; 25-OH D3 increased but to a lesser extent than the control. The effect might be related to EPG acting as a lipid "sink" during gastrointestinal transit. No effects were seen in secondary endpoint measures (physical exam, clinical pathology, serum folate, RBC folate, vitamin B12, zinc, iron, calcium, phosphorus, osteocalcin, RBP, intact PTH, PT, PTT, cholesterol, HDL-C, LDL-C, triglycerides). Gastrointestinal adverse events (gas with discharge; diarrhea; oily spotting; oily evacuation; oily stool; liquid stool; soft stool) were reported more frequently by subjects receiving 25 or 40 g/day of EPG. In general, the incidence and duration of these symptoms correlated directly with EPG dietary concentration. The results suggest 10 g/day of EPG was reasonably well tolerated.

Botanicals, selective insecticides, and predators to control Diaphorina citri (Hemiptera: Liviidae) in citrus orchards.

The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically important disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecticides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad-spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, average 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Aneglei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.

Contact allergy to ingredients of hair cosmetics - a comparison of female hairdressers and clients based on IVDK 2007-2012 data.

BACKGROUND: Cosmetics for bleaching, waving/relaxing and dyeing hair contain well-known allergens, leading to a substantial number of cases of allergic contact dermatitis. OBJECTIVE: To compare the frequency of important contact allergens (i) between two distinct groups of exposed patients, and (ii) with previous surveillance data. METHODS: On the basis of data collected by the Information Network of Departments of Dermatology (IVDK; www.ivkd.org) between 2007 and 2012 in 824 female hairdressers and 2067 female clients, the current spectrum of contact sensitization to ingredients of hair cosmetics, as contained in different pertinent series, is described. RESULTS: A similar burden of sensitization as in previous analyses was observed, but with some increase in sensitization to oxidative hair dye components in clients. Some allergens mainly affected hairdressers, such as ammonium persulfate (18.7% positive) and glyceryl monothioglycolate (GMTG; still 4.7% positive, with a few cases also in young hairdressers, despite removal from the German market). CONCLUSIONS: Hair dyes remain important contact allergens, despite various attempts by the cosmetic industry to introduce hair dyes with lower allergenic potential. The re-emergence of GMTG as an occupational allergen should be considered as a warning signal ('sentinel event') prompting close monitoring.

Treatment with Azadirachta indica in diabetic pregnant rats: negative effects on maternal outcome.

ETHNOPHARMACOLOGICAL RELEVANCE: The role of Azadirachta indica (neem) against Chagas disease and its antibiotic and antidiabetic action have been demonstrated in non-pregnant animals. However, the effects of neem on lipid metabolism and oxidative stress during pregnancy remain to be investigated. The objective of this study was to evaluate the effects of Azadirachta indica (neem) on maternal reproductive performance and biochemical parameters in non-diabetic and streptozotocin-induced mild diabetic rats (MD). MATERIALS AND METHODS: Pregnant rats were randomly distributed into six experimental groups: ND=non-treated non-diabetic (n=13); NDOil=non-diabetic treated with 1.2 mL/day neem seed oil (n=12); NDPA=non-diabetic treated with 1.0mg/mL/day azadirachtin (n=12); D=non-treated diabetic (n=13); DOil: diabetic treated with neem seed oil (n=12), and DPA=diabetic treated with azadirachtin, n=13. Treatment with either neem oil (1.2 mL/day) or azadirachtin (1.0mg/mL/day) was orally administered throughout pregnancy. Glucose test tolerance (GTT) was performed at day 17 of pregnancy and used as an inclusion criterion. At term pregnancy, maternal reproductive outcomes, lipid profile and oxidative stress status were assessed. RESULTS: Treatment with neem oil and azadirachtin during pregnancy (1) had no hypoglycemic and anti-hyperglycemic effects on non-diabetic and diabetic rats, respectively; (2) affected OGTT glycemic levels in diabetic rats; (3) increased the proportion of fetuses classified as small for pregnancy age (SPA) in all groups; and (4) did not interfere with the lipid profile in non-diabetic dams. Neem oil reduced the rate of total cholesterol and NEFA in diabetic animals. Both neem oil and azadirachtin increased lipoperoxidation, characterized by increased MDA levels in non-diabetic rats. CONCLUSION: Both neem seed oil and azadirachtin impaired intrauterine development and altered antioxidant/oxidative status during pregnancy.

A novel galacto-glycerolipid from Oxalis corniculata kills Entamoeba histolytica and Giardia lamblia.

Oxalis corniculata is a naturally occurring weed that has been used in traditional medicine for the cure of dysentery and diarrhea in India. One of the common causes of dysentery is due to infection by the protist pathogen Entamoeba histolytica. Bioactivity profiling of extracts from O. corniculata identified several compounds that showed antiamoebic activity in axenic cultures of E. histolytica. These were characterized by nuclear magnetic resonance, infrared, and mass spectrometry as (i) Oc-1, a mixture of saturated fatty acids C24 to C28; (ii) Oc-2, a mixture of long-chain alcohols C18 to C28; and (iii) Oc-3, a single compound that was a galacto-glycerolipid (GGL). Of the different compounds that were obtained, the strongest antiamoebic activity was found in GGL. The addition of GGL to E. histolytica xenic cultures containing other microbial flora from the large intestine did not affect its antiamoebic activity. Amoebicidal concentrations of GGL had no effect on intestinal microbial flora or on the mammalian cell line HEK-293. GGL was also found to be equally effective in killing another protist pathogen, Giardia lamblia, that causes diarrhea in humans. The importance of this study is based on the identification of novel natural products and the possibility of developing these compounds as active agents to treat at least two pathogenic parasitic intestinal infections endemic to tropical regions.

Hairdressers with dermatitis should always be patch tested regardless of atopy status.

BACKGROUND: Allergic contact dermatitis is common in hairdressers because of their exposure to chemicals used in hair dyes and permanent wave solutions. Atopic individuals are known to have a higher prevalence of leaving the profession due to morbidity associated with hand eczema. OBJECTIVES: To assess which chemicals are responsible for allergic contact dermatitis in hairdressers and whether the prevalence is the same according to atopy status. METHODS: A total of 729 hairdressers who had been patch tested were retrospectively identified. Allergic reactions to relevant allergens from the extended European baseline series and hairdressing series were analysed against history of atopic eczema. RESULTS: Of the total, 29.9% of patients had a current or past history of atopic eczema. The most frequent positive allergens from the European baseline series were nickel sulfate (32.1%) and p-phenylenediamine (19.0%) and from the hairdressing series were glyceryl monothioglycolate (21.4%) and ammonium persulfate (10.6%). There was no significant difference between people with or without a history of atopic eczema, except for fragrance mix I and nickel sulfate. CONCLUSIONS: We present findings from the largest cohort of hairdressers patch tested from a single centre. It is necessary to patch test hairdressers with dermatitis, regardless of a history of atopy. Strategies to reduce prevalence of allergic contact dermatitis are required.