The epistatic interaction between the dopamine D3 receptor and dysbindin-1 modulates higher-order cognitive functions in mice and humans.

The dopamine D2 and D3 receptors are implicated in schizophrenia and its pharmacological treatments. These receptors undergo intracellular trafficking processes that are modulated by dysbindin-1 (Dys). Indeed, Dys variants alter cognitive responses to antipsychotic drugs through D2-mediated mechanisms. However, the mechanism by which Dys might selectively interfere with the D3 receptor subtype is unknown. Here, we revealed an interaction between functional genetic variants altering Dys and D3. Specifically, both in patients with schizophrenia and in genetically modified mice, concomitant reduction in D3 and Dys functionality was associated with improved executive and working memory abilities. This D3/Dys interaction produced a D2/D3 imbalance favoring increased D2 signaling in the prefrontal cortex (PFC) but not in the striatum. No epistatic effects on the clinical positive and negative syndrome scale (PANSS) scores were evident, while only marginal effects on sensorimotor gating, locomotor functions, and social behavior were observed in mice. This genetic interaction between D3 and Dys suggests the D2/D3 imbalance in the PFC as a target for patient stratification and procognitive treatments in schizophrenia.

Nanoparticulated Systems Based on Natural Polymers Loaded with Miconazole Nitrate and Lidocaine for the Treatment of Topical Candidiasis.

People with weakened immune systems are at risk of developing candidiasis which is a fungal infection caused by several species of Candida genus. In this work, polymeric nanoparticles containing miconazole nitrate and the anesthetic lidocaine clorhydrate were developed. Miconazole was chosen as a typical drug to treat buccopharyngeal candidiasis whereas lidocaine may be useful in the management of the pain burning, and pruritus caused by the infection. Nanoparticles were synthesized using chitosan and gelatin at different ratios ranging from 10:90 to 90:10. The nano-systems presented nanometric size (between 80 and 300 nm in water; with polydispersion index ranging from 0.120 to 0.596), and positive Z potential (between 20.11 and 37.12 mV). The determined encapsulation efficiency ranges from 65 to 99% or 34 to 91% for miconazole nitrate and lidocaine clorhydrate, respectively. X-ray diffraction and DSC analysis suggested that both drugs were in amorphous state in the nanoparticles. Finally, the systems fitted best the Korsmeyer-Peppas model showing that the release from the nanoparticles was through diffusion allowing a sustained release of both drugs and prolonged the activity of miconazole nitrate over time against Candida albicans for at least 24 h.

Composite Microparticles Based on Natural Mucoadhesive Polymers with Promising Structural Properties to Protect and Improve the Antifungal Activity of Miconazole Nitrate.

Oropharyngeal candidiasis is a recurrent oral infection caused by Candida species. Gel formulation containing miconazole nitrate is the most common approach for treating oral candidiasis. However, traditional oral topical antifungal therapies have many limitations, including short contact time with the oral mucosa and the necessity to administrate various doses per day. Thus, the aim of this work was to formulate composited microparticulated systems based on combinations of mucoadhesive cationic, anionic, and nonionic polymers that could protect and modify the drug release rate and therefore avoid a fast dilution of the drug by saliva. Microparticulated systems were prepared by the spray drying method employing chitosan, gelatin, and hydroxypropyl methylcellulose. The morphology of the systems was investigated by scanning electron microscopy; drug crystallinity was studied by X-ray, while interactions between polymers were analyzed by infrared spectroscopy. Drug release and halo zone test were employed to analyze the release and activity of the systems loaded with miconazole against Candida albicans cultures. The most appropriate microparticulated system was the one based on chitosan and gelatin which showed homogeneous morphology (mean size of 1.7 ± 0.5 µm), a protective effect of the drug, and better antifungal effect against Candida culture than miconazole nitrate and the other assayed systems. Taking into account these results, this approach should be seriously considered for further evaluation of its safety and in vivo efficacy to be considered as an alternative therapeutic system for the treatment of oral candidiasis.

Formulation and in-vitro efficacy of antifungal mucoadhesive polymeric matrices for the delivery of miconazole nitrate.

Oral candidiasis is the most common opportunistic infection affecting patients with the human immunodeficiency virus. Miconazole buccal tablets or miconazole gel are approved for the treatment of oropharyngeal candidiasis. However, buccal films present more flexibility and also offer protection for the wounded mucosa, reducing pain. Due to their small size and thickness, buccal films may improve patients' compliance, compared to tablets. Additionally, they may increase the relatively short residence time on the mucosa of oral gels, which are easily removed by saliva. Polymeric films loaded with miconazole nitrate were prepared by a casting/solvent evaporation methodology using chitosan, carbopol, gelatin, gum arabic, and alginate to form the polymeric matrices. The morphology of films was investigated by scanning electron microscopy; interactions between polymers were analyzed by infrared spectroscopy and drug crystallinity by differential thermal analysis and X-ray diffraction. Films were characterized in terms of thickness, folding endurance, tensile properties, swelling, adhesiveness, and drug release. Finally, the antifungal activity against cultures of the five most important fungal opportunistic pathogens belonging to Candida genus was investigated. The more appropriate formulations were those based on chitosan-gelatin and chitosan-carbopol which showed good mechanical properties and adhesiveness, a relative low swelling index, improved drug release, and showed better in vitro activity against Candida cultures than miconazole nitrate raw material. Thus, it will be possible to produce a new pharmaceutical form based on polymeric films containing chitosan and miconazole nitrate, which could be loaded with low drug concentration producing the same therapeutic effect against Candida cultures.

Development and Evaluation of Buccal Films Based on Chitosan for the Potential Treatment of Oral Candidiasis.

In this work, chitosan films were prepared by a casting/solvent evaporation methodology using pectin or hydroxypropylmethyl cellulose to form polymeric matrices. Miconazole nitrate, as a model drug, was loaded into such formulations. These polymeric films were characterized in terms of mechanical properties, adhesiveness, and swelling as well as drug release. Besides, the morphology of raw materials and films was investigated by scanning electron microscopy; interactions between polymers were analyzed by infrared spectroscopy and drug crystallinity studied by differential scanning calorimetry and X-ray diffraction. In addition, antifungal activity against cultures of the five most important fungal opportunistic pathogens belonging to Candida genus was investigated. Chitosan:hydroxypropylmethyl cellulose films were found to be the most appropriate formulations in terms of folding endurance, mechanical properties, and adhesiveness. Also, an improvement in the dissolution rate of miconazole nitrate from the films up to 90% compared to the non-loaded drug was observed. The in vitro antifungal activity showed a significant activity of the model drug when it is loaded into chitosan films. These findings suggest that chitosan-based films are a promising approach to deliver miconazole nitrate for the treatment of candidiasis.

Oral infections caused by yeasts in patients with head and neck cancer undergoing radiotherapy. Identification of the yeasts and evaluation of their antifungal susceptibility.

UNLABELLED: Yeasts occur as part of the normal human microbiota. Nevertheless, some species are opportunistic, affecting immunocompromised patients such as those undergoing oncologic treatment. OBJECTIVE: To detect the presence of yeasts in patients suffering from head and neck cancer who are receiving radiation therapy and display lesions in the oral cavity, compatible with candidiasis; and to evaluate the antifungal susceptibility of the isolates recovered. METHODS: Sixty samples from patients were obtained by swabbing the oral mucosa. Identification of isolates were performed by classical taxonomic, morphological and biochemical methods as well as by using commercial identification kits. Susceptibility to antifungal drugs was determined by the agar diffusion method with Neosensitabs(®) disks. RESULTS: Forty-six samples (77%) yielded positive findings, and species recovered were: Candida albicans (22 isolates), Candida tropicalis (13 isolates), Candida parapsilosis (six strains), Candida krusei (three strains), Candida dubliniensis and Saccharomyces cerevisiae (one each). All strains were susceptible to itraconazole, clotrimazole, voriconazole, nystatin and amphotericin B. On the other hand, 65% of strains were miconazole-susceptible while 35%, showed intermediate susceptibility. With regard to ketoconazole, only three strains (7%) corresponding to C. albicans (one isolate) and C. krusei (two isolates) displayed intermediate susceptibility. Only C. krusei strains were resistant to fluconazole while all the other species were susceptible. Eventually, only six isolates (13%) were susceptible to terbinafine while the remaining strains were resistant in vitro. CONCLUSION: Early detection of etiological agents causing lesions, as well as the evaluation of their susceptibility to commonly used drugs, are crucial in order to choose the appropriate treatment that will minimize complications while improving the quality of patients' lives.

Antifungal, cytotoxic and SAR studies of a series of N-alkyl, N-aryl and N-alkylphenyl-1,4-pyrrolediones and related compounds.

The synthesis, in vitro evaluation and SAR studies of 67 maleimides and derivatives acting as antifungal agents are reported. A detailed SAR study supported by theoretical calculations led us to determine that: an intact maleimido ring appears to be necessary for a strong antifungal activity, dissimilarly affected by the substituents in positions 2 and 3. The best activities were shown by 2,3-nonsubstituted followed by 2,3 dichloro- and 2-methyl-substituted maleimides. They all were fungicide rather than fungistatic enhancing the importance of their antifungal activity. 2,3-Dimethyl and 2,3-diphenyl-maleimides possessed marginal or null activity. The presence of a flexible connecting chain in N-phenylalkyl maleimides appears not to be essential for antifungal activity, although its length shows a correlation with the antifungal behavior, displaying maleimides with alkyl chains of n=3 and n=4 the best antifungal activities in most fungi. Different substituents on the benzene ring did not have a clear influence on the activity. Values of chemical potential properties as well as of energy do not sufficiently discriminate between active and inactive compounds. Nevertheless, it was found that, although logP alone is not strong enough to properly predict the antifungal activity, the comparison of its values for compounds within the same sub-type, showed an enhancement of antifungal activity along with an increment of lipophilicity. In addition, the LUMO's electronic clouds of the highly active compounds showed to be concentrated on the imido ring, indicating that their carbon atoms are potential sites for nucleophilic attack. Same results were obtained from MEPs. Most of the active compounds did not show cytotoxic activity against human cancer cell lines and no one possessed hemolytic activity, indicating that their activity is selective to pathogenic fungi and that they are not toxic at MIC concentrations.

The cell cycle molecules behind neurodegeneration in Alzheimer's disease: perspectives for drug development.

Alzheimer's disease (AD), the leading cause of senile dementia, has become a considerable social and economical problem. Current AD therapeutics provide mainly symptomatic short-term benefit, rather than targeting disease mechanisms. The hallmarks for AD are beta-amyloid plaques, neurofibrillary tangles, and regionalized neuronal loss. Additional neuropathological features have been described that may provide some clues to the mechanism by which neurons die in AD. Specifically, the aberrant expression of cell cycle proteins and the presence of de novo-replicated DNA in neurons have been described both in AD brain and in culture models of the disease. The unscheduled cell cycle events are deleterious to neurons, which undergo death rather than complete the cell cycle. Although our understanding of the neuronal cell cycle is not complete, experimental evidence suggests that compounds able of arresting the aberrant cell cycle will yield neuroprotection. This review focuses on drug development centered on the cell cycle hypothesis of AD.

Progenitor cells from the adult mouse brain acquire a neuronal phenotype in response to beta-amyloid.

Neurospheres from adult mouse subventricular zone (SVZ) were grown in suspension cultures for 12-15 days. Neurospheres consisted mainly of neural precursor cells (NPCs) immunoreactive for nestin and also contained nestin-negative precursors. We used these neurospheres to determine the effects of synthetic beta-amyloid fragments (both betaAP(1-42) and betaAP(25-35)) on NPC proliferation, differentiation and survival. We show that neurospheres exposed to 25 microM betaAP(25-35) or betaAP(1-42) for 24 h (a toxic condition for mature neurons) did not undergo apoptosis. Instead, betaAP(25-35) orientated nestin-negative precursors towards nestin-positive NPCs and turned nestin-positive NPCs into neuroblasts. Intracerebroventricular infusion of full-length betaAP(1-42) increased the population of PSA-NCAM-positive cells in the SVZ, without affecting proliferation. We conclude that betaAP influences the fate of progenitor cells, driving their differentiation towards a neuronal lineage.

Antifungal activity of some Brazilian Hypericum species.

Crude methanolic extracts and fractions from the aerial parts of seven species of Hypericum (H. caprifoliatum Cham. and Schltdl., H. carinatum Griseb., H. connatum Lam., H. ternum A. St.-Hil., H. myrianthum Cham. and Schltdl., H. piriai Arechav. and H. polyanthemum Klotzsch ex Reichardt) growing in southern Brazil were analyzed for their in vitro antifungal activity against a panel of standardized and clinical opportunistic pathogenic yeasts and filamentous fungi, including dermatophytes, by the agar dilution method. Chloroform and hexane extracts of H. ternum showed the greatest activity among extracts tested.