The solubility of drugs in lipoid vehicles

A method for determination of drug substances solubility in lipophilic solvents is presented. The solubility was determined in lipophilic suppository bases meltings, in pharmaceutical lipoids as Oleum Ricini, Oleum Arachidis, Cera perliquida, Paraffinum perliquidum and in chemically defined lipoids as n-hexadecane, 1-hexadecane, cetylic alcohol, palmitic acid, cetylpalmitate. Consequences from chemical constitution of substances for solubility are discussed, also consequences from chemical constitution and dielectric constants of lipoidic solvents for their solution behavior. For the substances investigated, the apparent partition coefficients in the two-phase systems lipoid/phosphate buffer pH 7,4 and n-octanol/phosphate buffer pH 7,4 were determined, also the solubility in phosphate buffer. The results show, that connections between partition coefficients and solubility in lipophilic or aqueous phases do not exist. On the other hand, an indirect proportionality between water solubility and lipoid solubility also does not exist. In consequence, interpretations of drug release from lipophilic systems have to be proceeded from exact knowledge of partition behavior and solubilities in both the lipophilic and aqueous phase.     

Mitochondria and Energetic Depression in Cell Pathophysiology

Mitochondrial dysfunction is a hallmark of almost all diseases. Acquired or inherited mutations of the mitochondrial genome DNA may give rise to mitochondrial diseases. Another class of disorders, in which mitochondrial impairments are initiated by extramitochondrial factors, includes neurodegenerative diseases and syndromes resulting from typical pathological processes, such as hypoxia/ischemia, inflammation, intoxications, and carcinogenesis. Both classes of diseases lead to cellular energetic depression (CED), which is characterized by decreased cytosolic phosphorylation potential that suppresses the cell’s ability to do work and control the intracellular Ca²⁺ homeostasis and its redox state. If progressing, CED leads to cell death, whose type is linked to the functional status of the mitochondria. In the case of limited deterioration, when some amounts of ATP can still be generated due to oxidative phosphorylation (OXPHOS), mitochondria launch the apoptotic cell death program by release of cytochrome c. Following pronounced CED, cytoplasmic ATP levels fall below the thresholds required for processing the ATP-dependent apoptotic cascade and the cell dies from necrosis. Both types of death can be grouped together as a mitochondrial cell death (MCD). However, there exist multiple adaptive reactions aimed at protecting cells against CED. In this context, a metabolic shift characterized by suppression of OXPHOS combined with activation of aerobic glycolysis as the main pathway for ATP synthesis (Warburg effect) is of central importance. Whereas this type of adaptation is sufficiently effective to avoid CED and to control the cellular redox state, thereby ensuring the cell survival, it also favors the avoidance of apoptotic cell death. This scenario may underlie uncontrolled cellular proliferation and growth, eventually resulting in carcinogenesis.     

Biased recognition of positive faces in aging and amnestic mild cognitive impairment.

We investigated age differences in biased recognition of happy, neutral, or angry faces in 4 experiments. Experiment 1 revealed increased true and false recognition for happy faces in older adults, which persisted even when changing each face’s emotional expression from study to test in Experiment 2. In Experiment 3, we examined the influence of reduced memory capacity on the positivity-induced recognition bias, which showed the absence of emotion-induced memory enhancement but a preserved recognition bias for positive faces in patients with amnestic mild cognitive impairment compared with older adults with normal memory performance. In Experiment 4, we used semantic differentials to measure the connotations of happy and angry faces. Younger and older participants regarded happy faces as more familiar than angry faces, but the older group showed a larger recognition bias for happy faces. This finding indicates that older adults use a gist-based memory strategy based on a semantic association between positive emotion and familiarity. Moreover, older adults’ judgments of valence were more positive for both angry and happy faces, supporting the hypothesis of socioemotional selectivity. We propose that the positivity-induced recognition bias might be based on fluency, which in turn is based on both positivity-oriented emotional goals and on preexisting semantic associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antimicrobial,rheological, and physicochemical properties of sago starch films filled with nanorod-rich zinc oxide

The effects of zinc oxide nanorod incorporation on the flow properties of sago starch solution and antimicrobial, sorption isotherm, water vapor permeability, and UV transmission of sago starch films were investigated. The nanorod-rich ZnO (ZnO-N) was homogenized by sonication and incorporated into sago starch solutions at different concentrations (e.g. 1%, 2%, 3%, and 5% w/w dried starch). Introduction of low concentration ZnO-N to starch solutions significantly increased the viscosity of the solution and significantly decreased the permeability of the films to water vapor by less than one third. Solubility, moisture content, and monolayer water content of the films were decreased, whereas contact angle was increased with higher ZnO-N concentration. ZnO-N starch films had 0% UV transmittance and were able to absorb more than 80% of Near Infrared spectra. ZnO-N sago starch films exhibited excellent antimicrobial activity against Staphylococcus aureus. These properties suggest that ZnO nanorod has the potential as a filler in starch-based films for use as active packaging materials in the pharmaceutical and food industries.     

Chemical in situ polymerization of polypyrrole on poly(methyl metacrylate) substrate

Combination of electrically and optically active organic materials in one fiber would enable to realize several interesting smart systems in a simple and cost effective manner. In this work the coating of plastic optical material-poly(methyl metacrylate)-was carried out by in situ chemical polymerization of polypyrrole (PPy). Two ways of chemical polymerization were compared: (a) using FeCl₃ and (b) using ammonium peroxydisulphate with p-toluene sulfonic acid. Both planar and fiber samples were prepared. The samples are characterized by their surface resistivity and surface morphology. The influence of polymerization conditions like temperature, time and reactant concentration on surface resistivity is discussed. Optical transmission properties of PPy films are presented. The ageing of samples was studied within 4 weeks time.