Nanostructure formation in aqueous solution of amphiphilic copolymers of 2-(N,N-dimethylaminoethyl)methacrylate and alkylacrylate: Characterization, antimicrobial activity, DNA binding, and cytotoxicity studies.

Three amphiphilic random copolymers poly(2-(dimethylaminoethyl)methacrylate-co-alkylacrylate) (where, alkyl = hexyl, octyl, dodecyl) with 16 mol% hydrophobic substitution were synthesized. Surface tension, viscosity, fluorescence probe, dynamic light scattering (DLS), as well as transmission electron microscopic (TEM) techniques were utilized to investigate self-assembly formation by the hydrophobically modified polymers (HMPs) in pH 5. Formation of hydrophobic domains through inter-polymer chain interaction of the copolymer in dilute solution was confirmed by fluorescence probe studies.

Interaction between zwitterionic and anionic surfactants: spontaneous formation of zwitanionic vesicles.

The physicochemical properties, such as critical micelle concentration (cmc), surface tension at cmc (γ(cmc)), and surface activity parameters of the mixtures of a new amino acid-based zwitterionic surfactant, N-(n-dodecyl-2-aminoethanoyl)-glycine (C(12)Gly) and an anionic surfactant, sodium dodecyl sulfate (SDS) at different molar fractions, X(1) (= [C(12)Gly]/([C(12)Gly] + [SDS])) of C(12)Gly were studied. A synergistic interaction was observed between the surfactants in mixtures of different X(1). The self-organization of the mixtures at different molar fractions, concentrations, and pH was investigated.

Interaction of sodium N-lauroylsarcosinate with N-alkylpyridinium chloride surfactants: spontaneous formation of pH-responsive, stable vesicles in aqueous mixtures.

The interaction of sodium N-lauroylsarcosinate (SLS) with N-cetylpyridinium chloride (CPC) and N-dodecylpyridinium chloride (DPC) was investigated in aqueous mixtures. A strong interaction between the anionic and cationic surfactants was observed. The interaction parameter, β was determined for a wide composition range and was found to be negative.

Effect of sodium salicylate, sodium oxalate, and sodium chloride on the micellization and adsorption of sodium deoxycholate in aqueous solutions.

The salicylate ion increases the rate of bile flow (choleretic effect) and bile salts are known to affect the colonic absorption of oxalate. Owing to this physiological relevance of salicylate and oxalate ions, critical micelle concentration (cmc) values of sodium deoxycholate (NaDC) were determined in aqueous sodium oxalate, sodium salicylate, and sodium chloride solutions by using surface tension, fluorescence, and EMF methods. The results indicate, besides a counterion effect, the influence of coanions on the cmc.

Water-induced physical gelation of organic solvents by N-(n-alkylcarbamoyl)-L-alanine amphiphiles.

A series of amino acid-based gelators N-(n-alkylcarbamoyl)-L-alanine were synthesized, and their gelation abilities in a series of organic solvents were tested. No gelation was observed in pure solvents employed. All the amphiphilic molecules were found to form stable organogels in the solvents in the presence of a small amount of water, methanol, or urea.

Estimation and correction of cardiac respiratory motion in SPECT in the presence of limited-angle effects due to irregular respiration.

Purpose: One issue with amplitude binning list-mode studies in SPECT for respiratory motion correction is that variation in the patient's respiratory pattern will result in binned motion states with little or no counts at various projection angles. The reduced counts result in limited-angle reconstruction artifacts which can impact the accuracy of the necessary motion estimation needed to correct the images. In this work, the authors investigate a method to overcome the effect of limited-angle reconstruction artifacts in SPECT when estimating respiratory motion.

Amino acid based amphiphilic copolymer micelles as carriers of non-steroidal anti-inflammatory drugs: solubilization, in vitro release and biological evaluation.

Three novel amino acid based anionic amphiphilic copolymers poly(sodium N-acryloyl-l-valinate-co-alkylacrylamide) (where, alkyl=octyl and dodecyl) with either 9 or 16 mol% hydrophobic substitution were synthesized. These hydrophobically modified polyelectrolytes (HMPs), above a critical concentration, self-assemble in aqueous solution through inter-chain hydrophobic aggregation, forming micelle-like aggregates having hydrodynamic diameter in the range of 50-200 nm. The HMPs were found to undergo conformational changes with the change in solution pH, electrolyte and additive concentration, and temperature.

Internet administration of paper-and-pencil questionnaires used in couple research: assessing psychometric equivalence.

This study examined the psychometric equivalence of paper-and-pencil and Internet formats of key questionnaires used in couple research. Self-report questionnaires assessing interpersonal constructs (relationship satisfaction, communication/conflict management, partner support, emotional intimacy) and intrapersonal constructs (individual traits, psychological symptoms, contextual influences) were administered to young adults in committed dating relationships. The same measures were administered twice via paper-and-pencil and/or Internet methods over a 2-week period.

Micellar shape driven counterion binding. Small-angle neutron scattering study of AOT micelle.

Sodium dioctylsulfosuccinate (AOT) micelle has a special counterion binding behavior in aqueous electrolyte medium, viz., the counterion binding constant (β) abruptly increases by 2-fold at about 0.015 mol dm(-3) NaCl concentration (c*), but not in sodium salicylate (NaSa) solution.

Aggregation and adsorption behavior of cetylpyridinium chloride in aqueous sodium salicylate and sodium benzoate solutions.

The critical micelle concentration (cmc) values of cetylpyridinium chloride (CPC) were determined in the presence of salicylate and benzoate ions in the less explored concentration region where viscosity is Newtonian. The cmc of CPC decreased from 9 x 10(-4) to 7 x 10(-7) and 3 x 10(-6) mol kg(-1) by adding about 0.3 mol kg(-1) of salicylate and benzoate, respectively.

Interaction of anionic surfactant with polymeric nanoparticles of similar charge.

The formation of micelle-like nanosize aggregates above a critical aggregation concentration (CAC) by a water-soluble, amphiphilic, and statistical copolymer poly(SAMPS/DA) of sodium N-acrylamidomethylpropanesulfonate (SAMPS) and N-dodecylacrylamide (DA) was studied. The structural changes that result from the interactions between the polymeric nanoparticles and sodium dodecylsulfate (SDS), an anionic surfactant, were studied with the aid of surface tension, viscosity, steady-state fluorescence, dynamic light scattering, and transmission electron microscopic techniques. In dilute solution with polymer concentration C(p) View Article and Find Full Text PDF

Crosslinked urethane doped polyester biphasic scaffolds: Potential for in vivo vascular tissue engineering.

In vivo tissue engineering uses the body as a bioreactor for tissue regeneration, thus placing stringent requirements on tissue scaffolds, which should be mechanically robust for immediate implantation without a long in vitro cell culture time. In addition to mechanical strength, vascular grafts fabricated for in vivo tissue engineering approach must have matching mechanical properties to the target tissues to avoid compliance mismatch, which is one of the reasons for graft failure. We recently synthesized a new generation of strong and elastic biodegradable crosslinked urethane-doped polyesters (CUPE) to address the challenge of developing soft, elastic yet strong biodegradable polymers.

Potential for targeting the fibroblast growth factor receptors in breast cancer.

Breast cancer is the most common cancer of women, accounting yearly for approximately 30% of newly diagnosed cases and ranking second as a cause of death. Despite improvements in breast cancer detection and development of new therapeutic approaches, there are still tumors for which no targeted therapies are available. This review summarizes recent findings on the fibroblast growth factor receptors (FGFR) and the data supporting their role in breast cancer.

Targeting fibroblast growth factor receptors blocks PI3K/AKT signaling, induces apoptosis, and impairs mammary tumor outgrowth and metastasis.

Members of the fibroblast growth factor receptor (FGFR) family have essential roles in normal physiology and in cancer where they control diverse processes. FGFRs have been associated with breast cancer development. Thus, models to study the role of FGFR in breast cancer and their targeting potential are important.

Theoretical and Numerical Study of MLEM and OSEM Reconstruction Algorithms for Motion Correction in Emission Tomography.

Patient body-motion and respiratory-motion impacts the image quality of cardiac SPECT and PET perfusion images. Several algorithms exist in the literature to correct for motion within the iterative maximum-likelihood reconstruction framework. In this work, three algorithms are derived starting with Poisson statistics to correct for patient motion.

Estimation of Cardiac Respiratory-Motion by Semi-Automatic Segmentation and Registration of Non-Contrast-Enhanced 4D-CT Cardiac Datasets.

The goal of this work is to investigate, for a large set of patients, the motion of the heart with respiration during free-breathing supine medical imaging. For this purpose we analyzed the motion of the heart in 32 non-contrast enhanced respiratory-gated 4D-CT datasets acquired during quiet unconstrained breathing. The respiratory-gated CT images covered the cardiac region and were acquired at each of 10 stages of the respiratory cycle, with the first stage being end-inspiration.

Concentration and pH-dependent aggregation behavior of an l-histidine based amphiphile in aqueous solution.

The surface activity and self-assembly behavior of zwitterionic amphiphile N-(2-hydroxydodecyl)-l-histidine (C(12)HHis) were studied in phosphate buffers of pH 2 and 13 using surface tension and fluorescence probe techniques, respectively. Transmission electron microscopic images of the aggregates have revealed existence of nano-size vesicles in dilute solutions of both acidic and basic pH. In basic medium, the vesicles are converted to tubular aggregates upon increase of surfactant concentration.

A smart supramolecular hydrogel of N(alpha)-(4-n-alkyloxybenzoyl)-L-histidine exhibiting pH-modulated properties.

Six L-histidine-based amphiphiles, N(alpha)-(4-n-alkyloxybenzoyl)-L-histidine of different hydrocarbon chain lengths, were designed, synthesized, and examined for their ability to gelate water. Four of members of this family of amphiphiles were observed to form thermoreversible hydrogels in a wide range of pH at room temperature. The structural variations were characterized by critical gelation concentration, gelation time, gel melting temperature (T(gs)), rheology, and electron microscopy.

Birefringent physical gels of N-(4-n-alkyloxybenzoyl)-L-alanine amphiphiles in organic solvents: the role of hydrogen-bonding.

A new class of amphiphiles, N-(4-n-alkyloxybenzoyl)-L-alanine was designed and synthesized. These amphiphiles have been shown to form thermoreversible gels in organic solvents such as aromatic hydrocarbons, cyclohexane, and chlorinated hydrocarbons at room temperature. The effects of amide functionality, chain length of the hydrocarbon tail, and the chirality of the head group of the amphiphiles on the ability to promote gelation in organic solvents have been studied.

Salt, pH and thermoresponsive supramolecular hydrogel of N-(4-n-tetradecyloxybenzoyl)-L-carnosine.

A carnosine based amphiphilic hydrogelator has been developed which efficiently gelates water and exhibits salt, pH and thermoresponsive gelation properties.

Amphiphilic polymer nanoparticles: characterization and assessment as new drug carriers.

An amino-acid-based hydrophobically modified biocompatible copolymer, poly[(sodium N-acryloyl-L-valinate)-co-(N-octylacrylamide)] was synthesized and characterized. Techniques such as fluorescence probes, DLS, and TEM were used to investigate its aggregation behavior in aqueous solution. The copolymer was observed to form micellar aggregates having diameters in the nanometer range in aqueous solution (pH = 8) through inter-chain hydrophobic association.

Digital transcriptome profiling using selective hexamer priming for cDNA synthesis.

We developed a procedure for the preparation of whole transcriptome cDNA libraries depleted of ribosomal RNA from only 1 microg of total RNA. The method relies on a collection of short, computationally selected oligonucleotides, called 'not-so-random' (NSR) primers, to obtain full-length, strand-specific representation of nonribosomal RNA transcripts. In this study we validated the technique by profiling human whole brain and universal human reference RNA using ultra-high-throughput sequencing.

The serine protease inhibitor protease nexin-1 controls mammary cancer metastasis through LRP-1-mediated MMP-9 expression.

Through their ability to degrade the extracellular matrix, proteases mediate cancer cell invasion and metastasis. Paradoxically, some serine protease inhibitors (serpins) are often overexpressed in human tumors. Using computational analysis, we found that the RNA level of protease nexin-1 (PN-1), a serpin that blocks numerous proteases activity, is significantly elevated in estrogen receptor-alpha-negative and in high-grade breast cancer.

A flexible multicamera visual-tracking system for detecting and correcting motion-induced artifacts in cardiac SPECT slices.

Patient motion is inevitable in SPECT and PET due to the lengthy period of time patients are imaged. The authors hypothesized that the use of external-tracking devices which provide additional information on patient motion independent of SPECT data could be employed to provide a more robust correction than obtainable from data-driven methods. Therefore, the authors investigated the Vicon MX visual-tracking system (VTS) which utilizes near-infrared (NIR) cameras to stereo-image small retroreflective markers on stretchy bands wrapped about the chest and abdomen of patients during cardiac SPECT.

Development of aliphatic biodegradable photoluminescent polymers.

None of the current biodegradable polymers can function as both implant materials and fluorescent imaging probes. The objective of this study was to develop aliphatic biodegradable photoluminescent polymers (BPLPs) and their associated cross-linked variants (CBPLPs) for biomedical applications. BPLPs are degradable oligomers synthesized from biocompatible monomers including citric acid, aliphatic diols, and various amino acids via a convenient and cost-effective polycondensation reaction.