Morphology and surface properties of some siloxane–organic copolymers

BACKGROUND: It is well known that, due to their extremely low polarity, polysiloxanes are incompatible with almost any organic system. This incompatibility leads to phase separation in mixed siloxane–organic systems. RESULTS: Three siloxane–organic copolymers, poly[(5,5′‐methylene‐bis‐salicylaldehyde)‐imine‐(1,3‐bis(propylene)tetramethyldisiloxane)] (Paz1), poly[(2,5‐dihydroxy‐1,4‐benzoquinone)‐imine‐(1,3‐bis(propylene)tetramethyldisiloxane)] (Paz2) and poly[1,3‐bis(propylene)tetramethyldisiloxane diamide] (Pam), were prepared by the reaction of 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane with appropriate organic partners (5,5′‐methylene‐bis‐salicylaldehyde, 2,5‐dihydroxy‐1,4‐benzoquinone and oxalyl chloride, respectively). The morphologies dictated by the incompatibility between siloxane and polar organic moieties were investigated using differential scanning calorimetry and scanning electron microscopy. The surface activity of the copolymers and water vapour sorption capacity were also measured. CONCLUSION: Even though the polar sequences are very short ones, the highly flexible siloxane‐containing sequence permits the self‐assembly of these into more or less polar domains. Such an organization influences the properties of the resulting materials, an important place being occupied by the surface properties. Copyright © 2009 Society of Chemical Industry     

Stability during storage of LC-PUFA-supplemented infant formula containing single cell oil or egg yolk

The medical community recommends that infant formulae should mimic human milk as far as possible, particularly in regards to long-chain polyunsaturated fatty acids (LC-PUFA). These include arachidonic acid (AA) and docosahexaenoic acid (DHA), both of which provide biochemical and functional benefits to neonates. However, LC-PUFAs are highly susceptible to oxidation and the composition of formulae must be carefully controlled. In this study, the stability of two types of LC-PUFA-supplemented milk-based powdered infant formula was evaluated over the course of 18 months storage at 25 °C and 40 °C. One contained egg yolk phospholipids (IF-EPL) and the other contained triacylglycerides (DHA and AA) synthesized by single cell oils (IF-SCO). The following parameters were monitored: peroxide values, volatile content (propanal, pentanal and hexanal), fatty acid profiles, and potential and free furfural content (5-hydroxymethyl-2-furaldehyde and 2-furaldehyde). In addition, these formulae were subjected to sensory evaluations by a panel of experts. The parameters studied revealed acceptable lipid stability in both types of formula, with better results for IF-EPL. At the end of the study period, significant deficits (p < 0.05) in linoleic acid were noted in both formulae. However, no significant decreases were observed in the other fatty acids, including AA and DHA. In regards to furfural content, both formulae exhibited a similar increase, indicative of the typical Maillard reaction characteristic of products stored for long periods.     

Cellular and Molecular Targets for Non-Invasive,Non-Pharmacological Therapeutic/Rehabilitative Interventions in Acute Ischemic Stroke

BACKGROUND: Cerebral circulation delivers the blood flow to the brain through a dedicated network of sanguine vessels. A healthy human brain can regulate cerebral blood flow (CBF) according to any physiological or pathological challenges. The brain is protected by its self-regulatory mechanisms, which are dependent on neuronal and support cellular populations, including endothelial ones, as well as metabolic, and even myogenic factors. OBJECTIVES: Accumulating data suggest that “non-pharmacological” approaches might provide new opportunities for stroke therapy, such as electro-/acupuncture, hyperbaric oxygen therapy, hypothermia/cooling, photobiomodulation, therapeutic gases, transcranial direct current stimulations, or transcranial magnetic stimulations. We reviewed the recent data on the mechanisms and clinical implications of these non-pharmaceutical treatments. METHODS: To present the state-of-the-art for currently available non-invasive, non-pharmacological-related interventions in acute ischemic stroke, we accomplished this synthetic and systematic literature review based on the Preferred Reporting Items for Systematic Principles Reviews and Meta-Analyses (PRISMA). RESULTS: The initial number of obtained articles was 313. After fulfilling the five steps in the filtering/selection methodology, 54 fully eligible papers were selected for synthetic review. We enhanced our documentation with other bibliographic resources connected to our subject, identified in the literature within a non-standardized search, to fill the knowledge gaps. Fifteen clinical trials were also identified. DISCUSSION: Non-invasive, non-pharmacological therapeutic/rehabilitative interventions for acute ischemic stroke are mainly holistic therapies. Therefore, most of them are not yet routinely used in clinical practice, despite some possible beneficial effects, which have yet to be supplementarily proven in more related studies. Moreover, few of the identified clinical trials are already completed and most do not have final results. CONCLUSIONS: This review synthesizes the current findings on acute ischemic stroke therapeutic/rehabilitative interventions, described as non-invasive and non-pharmacological.     

Teriflunomide Preserves Neuronal Activity and Protects Mitochondria in Brain Slices Exposed to Oxidative Stress

Teriflunomide (TFN) limits relapses in relapsing–remitting multiple sclerosis (RRMS) by reducing lymphocytic proliferation through the inhibition of the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH) and the subsequent modulation of de novo pyrimidine synthesis. Alterations of mitochondrial function as a consequence of oxidative stress have been reported during neuroinflammation. Previously, we showed that TFN prevents alterations of mitochondrial motility caused by oxidative stress in peripheral axons. Here, we aimed to validate TFN effects on mitochondria and neuronal activity in hippocampal brain slices, in which cellular distribution and synaptic circuits are largely preserved. TFN effects on metabolism and neuronal activity were investigated by assessing oxygen partial pressure and local field potential in acute slices. Additionally, we imaged mitochondria in brain slices from the transgenic Thy1-CFP/COX8A)S2Lich/J (mitoCFP) mice using two-photon microscopy. Although TFN could not prevent oxidative stress-related depletion of ATP, it preserved oxygen consumption and neuronal activity in CNS tissue during oxidative stress. Furthermore, TFN prevented mitochondrial shortening and fragmentation of puncta-shaped and network mitochondria during oxidative stress. Regarding motility, TFN accentuated the decrease in mitochondrial displacement and increase in speed observed during oxidative stress. Importantly, these effects were not associated with neuronal viability and did not lead to axonal damage. In conclusion, during conditions of oxidative stress, TFN preserves the functionality of neurons and prevents morphological and motility alterations of mitochondria.     

Fetal Undernutrition Modifies Vascular RAS Balance Enhancing Oxidative Damage and Contributing to Remodeling

Fetal stress is known to increase susceptibility to cardiometabolic diseases and hypertension in adult age in a process known as fetal programming. This study investigated the relationship between vascular RAS, oxidative damage and remodeling in fetal programming. Six-month old Sprague-Dawley offspring from mothers that were fed ad libitum (CONTROL) or with 50% intake during the second half of gestation (maternal undernutrition, MUN) were used. qPCR or immunohistochemistry were used to obtain the expression of receptors and enzymes. Plasma levels of carbonyls were measured by spectrophotometry. In mesenteric arteries from MUN rats we detected an upregulation of ACE, ACE2, AT₁ receptors and NADPH oxidase, and lower expression of AT₂, Mas and MrgD receptors compared to CONTROL. Systolic and diastolic blood pressure and plasma levels of carbonyls were higher in MUN than in CONTROL. Vascular morphology evidenced an increased media/lumen ratio and adventitia/lumen ratio, and more connective tissue in MUN compared to CONTROL. In conclusion, fetal undernutrition indices RAS alterations and oxidative damage which may contribute to the remodeling of mesenteric arteries, and increase the risk of adverse cardiovascular events and hypertension.     

Medicated Scaffolds Prepared with Hydroxyapatite/Streptomycin Nanoparticles Encapsulated into Polylactide Microfibers

The preparation, characterization, and controlled release of hydroxyapatite (HAp) nanoparticles loaded with streptomycin (STR) was studied. These nanoparticles are highly appropriate for the treatment of bacterial infections and are also promising for the treatment of cancer cells. The analyses involved scanning electron microscopy, dynamic light scattering (DLS) and Z-potential measurements, as well as infrared spectroscopy and X-ray diffraction. Both amorphous (ACP) and crystalline (cHAp) hydroxyapatite nanoparticles were considered since they differ in their release behavior (faster and slower for amorphous and crystalline particles, respectively). The encapsulated nanoparticles were finally incorporated into biodegradable and biocompatible polylactide (PLA) scaffolds. The STR load was carried out following different pathways during the synthesis/precipitation of the nanoparticles (i.e., nucleation steps) and also by simple adsorption once the nanoparticles were formed. The loaded nanoparticles were biocompatible according to the study of the cytotoxicity of extracts using different cell lines. FTIR microspectroscopy was also employed to evaluate the cytotoxic effect on cancer cell lines of nanoparticles internalized by endocytosis. The results were promising when amorphous nanoparticles were employed. The nanoparticles loaded with STR increased their size and changed their superficial negative charge to positive. The nanoparticles’ crystallinity decreased, with the consequence that their crystal sizes reduced, when STR was incorporated into their structure. STR maintained its antibacterial activity, although it was reduced during the adsorption into the nanoparticles formed. The STR release was faster from the amorphous ACP nanoparticles and slower from the crystalline cHAp nanoparticles. However, in both cases, the STR release was slower when incorporated in calcium and phosphate during the synthesis. The biocompatibility of these nanoparticles was assayed by two approximations. When extracts from the nanoparticles were evaluated in cultures of cell lines, no cytotoxic damage was observed at concentrations of less than 10 mg/mL. This demonstrated their biocompatibility. Another experiment using FTIR microspectroscopy evaluated the cytotoxic effect of nanoparticles internalized by endocytosis in cancer cells. The results demonstrated slight damage to the biomacromolecules when the cells were treated with ACP nanoparticles. Both ACP and cHAp nanoparticles were efficiently encapsulated in PLA electrospun matrices, providing functionality and bioactive properties.     

Acylierung von Heterocyclen mit Kohlensäurederivaten. I. Kinetik und Mechanismus der Reaktion von 2-Aminobenzimidazolen mit Arylcyanaten

Acylation of Heterocycles with Carbonic Acid Derivatives. I. Kinetics and Mechanism of the Reaction of 2-Aminobenzimidazoles with Aryl Cyanates The second order rate constants for the reaction of 2-amino-benzimidazoles (2-ABI) with aryl cyanates forming 2-amino-benzimidazole aryl ester imide 3 have been determined in dependence on substituent effects by u. v. measurements. The results are interpreted by a six-membered cyclic transition state in which the electrophilic attack of the cyanate on the endocyclic N atom is catalyzed by an H bridge interaction of the exocyclic amino group of 2-ABI with the OCN group.     

Vitamins A and E content in infant milk-based powdered formulae after opening the packet

Vitamins A and E were determined by HPLC in 20 starting, milk-based powdered infant formulae from local markets. We traced the evolution of these compounds, once the packets had been opened, during 0, 30 and 70 days of storage at room temperature (≈25 °C; min. 23 °C, max. 25.5 °C). Immediately after opening the packets, vitamin A ranged from 0.55 to 0.94 mg RE/100 g (93.3–183 μg RE/100 kcal) and vitamin E from 6.58 to 27.8 mg α-TE/100 g (1.36–5.39 mg α-TE/100 kcal). All the samples had higher vitamins A and E contents than those declared on the label, vitamin A mean adequacy values: 134% ± 17, min. 98%, max. 162%, and vitamin E 185% ± 47, min. 101%, max. 286%, including values at 0, 30 and 70 days of storage.     

Intracellular silver accumulation in Chlamydomonas reinhardtii upon exposure to carbonate coated silver nanoparticles and silver nitrate

The intracellular silver accumulation ({Ag}(in)) upon exposure to carbonate coated silver nanoparticles (AgNP, 0.5-10 μM, average diameter 29 nm) and silver nitrate (20-500 nM) was examined in the wild type and in the cell wall free mutant of the green alga Chlamydomonas reinhardtii at pH 7.5. The {Ag}(in) was measured over time up to 1 h after a wash procedure to remove silver ions (Ag(+)) and AgNP from the algal cell surface. The {Ag}(in) increased with increasing exposure time and with increasing AgNP and AgNO(3) concentrations in the exposure media, reaching steady-state concentrations between 10(-5) and 10(-3) mol L(cell)(-1). According to estimated kinetic parameters, high Ag(+) bioconcentration factors were calculated (>10(3) L L(cell)(-1)). Higher accumulation rate constants were assessed in the cell wall free mutant, indicating a protective role of the cell wall in limiting Ag(+) uptake. The bioavailability of AgNP was calculated to be low in both strains relative to Ag(+), suggesting that AgNP internalization across the cell membrane was limited.     

The Effect of Food Type (Fish Nuggets or French Fries) on Oil Blend Degradation during Repeated Frying

Abstract: Oil that is reused multiple times for deep frying goes through changes in chemical composition and physical characteristics, affecting the quality of the fried foods. In this study, the effect of the food type (fish nuggets or French fries) on the degradation of an oil blend during the deep‐fat frying of each food at 180°C during 12 days was determined, and the characteristics of the fried products were evaluated. The degradation of oil during repeated use was relatively faster when fish nuggets were fried than when French fries were fried, as higher values of total polar compounds were obtained. Practical Application: The results are useful for producers of French fries and fish nuggets, such as restaurants or fast foods sellers, providing them with practical guidelines within the permitted values established by the regulatory authorities. The studied foods have high economic importance and are different in their composition. Under the studied conditions, the tested oil blend may be used during 4 d (4 h per day) with a daily replenishment, without discarding the oil when frying fish nuggets, and must be discarded after 8 d when French fries are processed. This suggestion allows preparing safe fried foods for consumers.