bluuebunny/crossref_metadata_2025 huggingface dataset:
Foxo Transcription Factors Blunt Cardiac Hypertrophy by Inhibiting Calcineurin Signaling
Authors: Ni Yan G. , Berenji Kambeez , Wang Na , Oh Misook , Sachan Nita , Dey Asim , Cheng Jun , Lu Guangrong , Morris David J. , Castrillon Diego H. , Gerard Robert D. , Rothermel Beverly A. , Hill Joseph A.
Published: September 2006

Background—

Cellular hypertrophy requires coordinated regulation of progrowth and antigrowth mechanisms. In cultured neonatal cardiomyocytes, Foxo transcription factors trigger an atrophy-related gene program that counters hypertrophic growth. However, downstream molecular events are not yet well defined.

Methods and Results—

Here, we report that expression of either Foxo1 or Foxo3 in cardiomyocytes attenuates calcineurin phosphatase activity and inhibits agonist-induced hypertrophic growth. Consistent with these results, Foxo proteins decrease calcineurin phosphatase activity and repress both basal and hypertrophic agonist-induced expression of MCIP1.4, a direct downstream target of the calcineurin/NFAT pathway. Furthermore, hearts from Foxo3-null mice exhibit increased MCIP1.4 abundance and a hypertrophic phenotype with normal systolic function at baseline. Together, these results suggest that Foxo proteins repress cardiac growth at least in part through inhibition of the calcineurin/NFAT pathway. Given that hypertrophic growth of the heart occurs in multiple contexts, our findings also suggest that certain hypertrophic signals are capable of overriding the antigrowth program induced by Foxo. Consistent with this, multiple hypertrophic agonists triggered inactivation of Foxo proteins in cardiomyocytes through a mechanism requiring the PI3K/Akt pathway. In addition, both Foxo1 and Foxo3 are phosphorylated and consequently inactivated in hearts undergoing hypertrophic growth induced by hemodynamic stress.

Conclusions—

This study suggests that inhibition of the calcineurin/NFAT signaling cascade by Foxo and release of this repressive action by the PI3K/Akt pathway are important mechanisms whereby Foxo factors govern cell growth in the heart.
From Machine and Tape to Structure and Function: Formulation of a Reflexively Computing System
Authors: Salzberg Chris
Published: September 2006

The relationship between structure and function is explored via a system of labeled directed graph structures upon which a single elementary read/write rule is applied locally. Boundaries between static (information-carrying) and active (information-processing) objects, imposed by mandate of the rules or physics in earlier models, emerge instead as a result of a structure-function dynamic that is reflexive: objects may operate directly on their own structure. A representation of an arbitrary Turing machine is reproduced in terms of structural constraints by means of a simple mapping from tape squares and machine states to a uniform medium of nodes and links, establishing computation universality. Exploiting flexibility of the formulation, examples of other unconventional “self-computing” structures are demonstrated. A straightforward representation of a kinematic machine system based on the model devised by Laing is also reproduced in detail. Implications of the findings are discussed in terms of their relation to other formal models of computation and construction. It is argued that reflexivity of the structure-function relationship is a critical informational dynamic in biochemical systems, overlooked in previous models but well captured by the proposed formulation.
Through the Interaction of Neutral and Adaptive Mutations, Evolutionary Search Finds a Way
Authors: Yu Tina , Miller Julian Francis
Published: September 2006

An evolutionary system that supports the interaction of neutral and adaptive mutations is investigated. Experimental results on a Boolean function and needle-in-haystack problems show that this system enables evolutionary search to find better solutions faster. Through a novel analysis based on the ratio of neutral to adaptive mutations, we identify this interaction as an engine that automatically adjusts the relative amounts of exploration and exploitation to achieve effective search (i.e., it is self-adaptive). Moreover, a hypothesis to describe the search process in this system is proposed and investigated. Our findings lead us to counter the arguments of those who dismiss the usefulness of neutrality. We argue that the benefits of neutrality are intimately related to its implementation, so that one must be cautious about making general claims about its merits or demerits.
Genetic Stability and Territorial Structure Facilitate the Evolution of Tag-Mediated Altruism
Authors: Spector Lee , Klein Jon
Published: September 2006

Evolutionary theorists have long been interested in the conditions that permit the evolution of altruistic cooperation. Recent work has demonstrated that altruistic donation can evolve in surprisingly simple models, in which agents base their decisions to donate solely on the similarity of evolved “tags” relative to evolved tag-difference tolerances. There is disagreement, however, about the conditions under which tag-mediated altruism will in fact evolve. Here we vary two critical parameters in a standard model of tag-mediated altruism—genetic stability and territorial structure—and show that altruism evolves in a wide range of conditions. We demonstrate the evolution of significant levels of altruism even when the immediate costs to donors equal the benefits to recipients. We describe the mechanism that permits the emergence of altruism in the model as a form of kin selection that is facilitated by interactions between altruism, genetic drift, and fecundity.
Simulating the Hallmarks of Cancer
Authors: Abbott Robert G. , Forrest Stephanie , Pienta Kenneth J.
Published: September 2006

Cancer can be viewed as the loss of cooperative cell behaviors that normally facilitate multicellularity, including the formation of tissues and organs. Hanahan and Weinberg describe the phenotypic differences between healthy and cancerous cells in an article titled “The Hallmarks of Cancer” (Cell, 100, 57–70, 2000). Here the authors propose six phenotypic changes at the cellular level as the essential hallmarks of cancer. They investigate the dynamics and interactions of these hallmarks in a model known as CancerSim. They describe how CancerSim implements the hallmarks in an agent-based simulation which can help test the hypotheses put forth by Hanahan and Weinberg. Experiments with CancerSim are described that study the interactions of cell phenotype alterations, and in particular, the likely sequences of precancerous mutations, known as pathways. The experiments show that sequencing is an important factor in tumorigenesis, as some mutations have preconditions—they are selectively advantageous only in combination with other mutations. CancerSim enables a modeler to study the dynamics of a developing tumor and simulate how progression can be altered by tuning model parameters.
Intracellular Delivery of Cysteine Protease Inhibitor Cystatin by Polymeric Nanoparticles
Authors: Cegnar Mateja , Kos Janko , Kristl Julijana
Published: September 2006

Two polymers chitosan and poly(lactide-co-glycolide) copolymer (PLGA) were investigated to develop nanoparticles (NPs) for delivery of protein drug substance into tumour cells. Cystatin was selected as a model protein drug due to its high potential to inhibit cysteine proteases, known
to trigger the invasive process. Ionotropic gelation of chitosan with tripolyposphate and precipitation of PLGA polymer from a double emulsion system by a solvent diffusion process were used to produce 250–300 nm in diameter NPs. The cellular uptake of NPs was tested on a transformed
human breast epithelial cell line, MCF-10A neoT, characterized by an increased expression of cysteine proteases and highly invasive cell phenotype. The influence of NPs on cell viability was evaluated by MTT test showing IC50 400 μg/ml for PLGA and 5 mg/ml for chitosan
NPs. As determined by fluorescence microscopy chitosan NPs did not enter the cells during 1-hour incubation whereas the same amount of PLGA NPs were in the cells already after 5 min of incubation. Cystatin delivered into MCF-10A neoT cells by PLGA NPs effectively inhibited intracellular proteolytic
activity of cathepsin B, as detected by specific fluorogenic substrate Z-Arg2 cresyl violet. On the contrary, free cystatin in solution did not internalise into the cells and inhibit cathepsin B. To conclude, PLGA NPs with cystatin but not chitosan NPs were targeted through endocytosis
to the lysosomal compartments that are rich of proteases enzymes. Our results suggest new strategy to inactivate intracellular tumour-associated proteases, and consequently the invasion behaviour of tumour cells, which could contribute to cancer therapy.
Preparation, Characterization and In Vivo Studies of Proliposomes Containing Cyclosporine A
Authors: Shah Neha M. , Parikh Jolly , Namdeo Alok , Subramanian N. , Bhowmick Subhash
Published: September 2006

The present study was undertaken to prepare proliposomes of Cyclosporine A (CsA) to increase its oral bioavailability. The proliposomes were prepared by spraying a solution of CsA, egg lecithin and cremophor EL® in methanol-chloroform mixture onto directly compressible
lactose (carrier) in a rotary evaporator. A dry free flowing powder of proliposomes was obtained. The dry proliposomal powder was characterized for surface morphology by scanning electron microscopy (SEM). Then the proliposomes were hydrated with distilled water to produce liposomes, which
were characterized for particle size distribution, % drug entrapment, and morphological characteristics by transmission electron microscopy (TEM). The liposomes exhibited good entrapment of about 99%. The entrapment of CsA in liposomes was found to be dependent mainly on the drug:lipid ratio.
Bioavailability studies were carried out for three different formulations of CsA i.e., free drug suspension; proliposomes derived liposomes and marketed formulation (Pannimun Bioral®, Microemulsion) on male SD rats. The results of bioavailability studies indicated that the difference in
the mean drug concentration of the free drug and the liposomes was found to be statistically significant (p < 0 05, p value is 0.032). The absorption constant for liposomal product was much greater (10.26 h−1) than for free drug solution (1.2 h−1)
or the marketed sample of microemulsion (2.51 h−1) and the volume of distribution was found to be less for liposomes (7629.88 ml/kg) than that of the free drug solution (10971.92 ml/kg) and marketed microemulsion (9012.07 ml/kg). The results of these studies have shown that
a stable proliposomal formulation of CsA for oral administration can be prepared which can be easily hydrated into liposomes from which CsA can exert its clinical effects with a better oral bioavailability.
Preparation and Characterization of Insulin Nanoparticles Employing Chitosan and Poly(methylmethacrylate/methylmethacrylic acid) Copolymer
Authors: Li Ming-Guang , Lu Wan-Liang , Wang Jian-Cheng , Zhang Xuan , Zhang Hua , Wang Xue-Qing , Wu Cui-Shuan , Zhang Qiang
Published: September 2006

As most of polypeptides are marginally stable, a mild formulation procedure would be beneficial for the activities of these drugs. The objective of the present study was to develop a novel pH-sensitive nanoparticle system that was suitable for entrapment of hydrophilic insulin but without
affecting its conformation. Chitosan was incorporated as a positively charged material, and one of the three poly(methylmethacrylate/methylmethacrylic acid) copolymers, consisting of Eudragit L100-55, L100, and S100, was used as a negatively charged polymer for preparation of three insulin
nanoparticles, respectively. Three nanoparticles obtained were spherical. The mean diameters were in the range from 200 nm to 250 nm, and the entrapment efficiencies, from 50% to 70%. The surface analysis indicated that insulin was evenly distributed in the nanoparticles. Polymer ratio of
chitosan to Eudragit was the factor which influenced the nanoparticles significantly. Characterization results showed that the electrostatic interactions existed, thus providing a mild formulation procedure which did not affect the chemical integrity and the conformation of insulin. In
vitro release studies revealed that all three types of the nanoparticles exhibited a pH-dependant characteristic. The modeling data indicated that the release kinetics of insulin was nonlinear, and during the release process, the nanoparticles showed a polynomial swelling. On overall estimation,
the insulin chitosan-Eudragit L100-55 nanoparticles may be better for the oral delivery. This new pH-sensitive nanoparticle formulation using chitosan and Eudragit L100-55 polymer may provide a useful approach for entrapment of hydrophilic polypeptides without affecting their conformation.
Bioerodible Polymeric Nanoparticles for Targeted Delivery of Proteic Drugs
Authors: Chiellini Elisabetta E. , Chiellini Federica , Solaro Roberto
Published: September 2006

Significant efforts are being devoted to develop nanotechnology for drug delivery, mainly because of the distinct advantages offered by nanometer-size polymeric systems. Moreover, targeted drug delivery can be obtained by polymer conjugation to biospecific ligands. The present investigation
was aimed mainly at determining the targeting ability of hybrid nanoparticles based on synthetic polymer/protein hybrid matrices. These nanoparticles were designed for liver targeted release of proteic drugs with antiviral activity, such as α-interferon. Human serum albumin and
the monoesters of alternating copolymers of maleic anhydride/alkyl vinyl ethers of oligo(ethylene glycol) were selected as proteic and synthetic components, respectively. Digalactosyl diacyl glycerol, a natural glycolipid selectively recognized by the asialofetuin receptor present on liver
hepatocytes was used as active targeting agent. Nanoparticles of 100–300 nm average size were obtained by controlled coprecipitation method. Investigation of nanoparticle surface properties by spectroscopic analysis and by biological tests indicated that the synthesized nanoparticles
do expose on their surface targeting moieties that selectively interact with liver hepatocytes receptors.
Pharmacytes: An Ideal Vehicle for Targeted Drug Delivery
Authors: Freitas Robert A.
Published: September 2006

An ideal nanotechnology-based drug delivery system is a pharmacyte—a self-powered, computer-controlled medical nanorobot system capable of digitally precise transport, timing, and targeted delivery of pharmaceutical agents to specific cellular and intracellular destinations within
the human body. Pharmacytes may be constructed using future molecular manufacturing technologies such as diamond mechanosynthesis which are currently being investigated theoretically using quantum ab initio and density-functional computational methods. Pharmacytes will have many applications
in nanomedicine such as initiation of apoptosis in cancer cells and direct control of cell signaling processes.
Intracellular Delivery of Poly(ethylene glycol) Conjugated Antisense Oligonucleotide Using Cationic Lipids by Formation of Self-Assembled Polyelectrolyte Complex Micelles
Authors: Jeong Ji Hoon , Kim Sun Hwa , Kim Sung Wan , Park Tae Gwan
Published: September 2006

A polyelectrolyte complex (PEC) micelle-based antisense oligodeoxynucleotide (ODN) delivery system was designed to overcome intrinsic limitations of cationic lipid-mediated gene transfer. Cationic lipid (Lipofectamine™, LF) and ODN conjugated poly(ethylene glycol) (PEG)
were ionically complexed to form self-assembled spherical PEC micelles. They have a distinctive structural feature: a charge-neutralized core surrounded by highly flexible PEG corona. The PEC micelles could be visualized as a nano-sized sphere by atomic force microscopy (AFM). The DNA/LF PEC
micelles exhibited far improved transfection efficiency compared to those of conventional lipoplex formulations (ODN/LF) in the presence of serum. They showed enhanced cellular uptake followed by rapid nuclear localization of ODN in human epithelial carcinoma (KB) cells. In addition, anti-proliferative
activity of c-raf gene-directed antisense ODN was almost fully maintained in KB cells in the presence of serum.
Physico-Chemical Characterization and In Vivo Evaluation of Indomethacin Ethyl Ester-Loaded Nanocapsules by PCS, TEM, SAXS, Interfacial Alkaline Hydrolysis and Antiedematogenic Activity
Authors: Cruz Letícia , Schaffazick Scheila R. , Costa Teresa Dalla , Soares Leonardo U. , Mezzalira Graziela , da Silveira Nádya P. , Schapoval Elfrides E. S. , Pohlmann Adriana R. , Guterres Sílvia S.
Published: September 2006

Nanocapsules are vesicular drug carriers constituted of an oil core, a polymeric wall, and surfactants. A general understanding about the influence of the polymeric wall of nanocapsules on the release profiles of drugs is not known. So, this work was devoted to characterize formulations
prepared without polymer or containing it at different concentrations. The indomethacin ethyl ester was used as model and the strategy was based on its interfacial alkaline hydrolysis simulating a sink condition for the release. The antiedematogenic activity in rats for ester-loaded-nanocarriers
was also evaluated. The nanocapsules (NC) and nanoemulsion (NE) presented particle sizes below 300 nm, polydispersity lower than 1.2 and pH around 5. SAXS analyses showed that the sorbitan monostearate is dissolved in the oil and the polymer presents regions of crystallinity independently
on the PCL concentration. TEM analyses showed droplets (NE) and spherical particles (NC). The time for the total disappearance of the ester varied from 12 h to 24 h depending on the polymer concentration. The biexponential model showed that the indomethacin ester was essentially entrapped
within the nanocarriers in an extension of 85 to 95%. The half-lives varied from 147 to 289 min for the sustained phases and from 3 to 6 min for the burst phases. The ester-loaded-NC showed significant antiedematogenic activity, while the ester-loaded-NE did not inhibit the carrageenin-induced
paw edema. The nanocapsules promoted the absorption of the indomethacin ethyl ester and the presence of the polymer is important to achieve the pharmacological effect.
Development and Evaluation of Emulsion-Liposome Blends for Resveratrol Delivery
Authors: Hung Chi-Feng , Chen Jan-Kan , Liao Mei-Hui , Lo Huey-Ming , Fang Jia-You
Published: September 2006

Nano- and submicron-sized vesicles are beneficial for the controlled delivery of drugs. Resveratrol, the main active polyphenol in red wine, was incorporated into various combinations of emulsions and liposomes to examine its physicochemical characteristics and cardiovascular protection.
The blends of emulsion-liposome were composed of coconut oil, soybean lecithin, glycerol formal, and non-ionic surfactants. Multiple systems were assessed by evaluating the droplet size, surface charge, drug encapsulation, release rate, and stability. The vesicle diameter of the systems ranged
from 114 to 195 nm. The liposomal vesicles in the systems had smaller diameters (of 43 ∼ 56 nm) (F6 and F7). Drug encapsulation of ∼70% were achieved by the vesicles. The inclusion of resveratrol in these systems retarded the drug release in both the presence and absence of plasma
in vitro. The emulsion-liposome blends which incorporated Brij 98 (F5) exhibited the slowest release at zero-order for resveratrol delivery. Treatment using resveratrol in the blended formulations dramatically inhibited vascular intimal thickening, which was tested in an experimental
model in which endothelial injury was produced in normal rat carotid arteries. Intraperitoneal injection of the multiple systems was associated with no or negligible liver and kidney toxicity. We concluded that encapsulation by the emulsion-liposome blends is a potent way to enhance the preventative
and therapeutic benefits of resveratrol.
Arsonoliposome Interaction with Thiols: Effect of Pegylation and Arsonolipid Content of Arsonoliposomes on Their Integrity During Incubation in Glutathione
Authors: Haikou Maria N. , Zagana Paraskevi , Ioannou Panayiotis V. , Antimisiaris Sophia G.
Published: September 2006

Increased toxicity of arsonoliposomes towards cancer cells may be attributed to interaction between arsonolipids and cellular thiols which, would result in reduction of As(V) to the more toxic As(III). Cancer cells with high thiol contents may thus be more sensitive to arsonoliposomes,
providing that the arsonolipid molecules that are incorporated in the liposome membrane can interact with thiol-containing compounds. For examination of this possibility we investigate the effect of incubating various compositions of arsonoliposomes with glutathione, on their integrity. If
glutathione does interact with the As(V) of the arsonolipid headgroup, this should result in an alteration of the arsonoliposome membrane stability. We followed arsonoliposome integrity by measuring the release of vesicle-encapsulated calcein from arsonoliposomes with different lipid compositions,
during incubation in glutathione. The results of this study show that the effect of glutathione on arsonoliposome integrity is higher (arsonoliposomes are less stable) when the arsonolipid content of their membranes increases. This indicates that arsonolipid molecules interact with glutathione,
and in some cases, depending on the rigidity of their membranes; this interaction leads to a (higher or lower) destabilization of arsonoliposomes. The destabilizing effect of glutathione was higher for arsonoliposomes that were previously found to be less stable during incubation in serum
proteins or, in other words, have lower membrane rigidity. In the case of pegylated-arsonoliposomes membrane destabilization was minimal and this may be related to the high stability demonstrated previously for these specific arsonoliposomes, or, it may indicate that pegylation results in
prevention (total or partial) of arsonolipid–As interaction with thiols (perhaps because of steric repulsion).
Intracellular Accumulation and Cytotoxicity of Doxorubicin with Different Pharmaceutical Formulations in Human Cancer Cell Lines
Authors: Serpe Loredana , Guido Marilena , Canaparo Roberto , Muntoni Elisabetta , Cavalli Roberta , Panzanelli Patrizia , Pepa Carlo Della , Bargoni Alessandro , Mauro Alessandro , Gasco Maria Rosa , Eandi Mario , Zara Gian Paolo
Published: September 2006

The structure of both carrier and anticancer drug affects the intracellular fate of a transported drug. The study investigated in vitro intracellular accumulation and cytotoxic activity of doxorubicin-loaded solid lipid nanoparticles (SLN), doxorubicin in pegylated liposomes
(Caelyx®) and free doxorubicin. Intracellular doxorubicin levels and cytotoxic activity were determined by high performance liquid chromatography with fluorescence detection, and by the trypan blue dye exclusion assay, respectively. Doxorubicin-loaded SLN inhibited
cell growth more strongly than either free or liposomal doxorubicin, in human colorectal adenocarcinoma, HT-29, retinoblastoma Y79, and glioblastoma U373 cell lines. The IC50 values for doxorubicin-loaded SLN were significantly lower after 24 h exposure than those for free doxorubicin
in all cell lines; after 48 h exposure they were lower than those for liposomal doxorubicin in HT-29 and Y79 cells. The enhanced cytotoxic activity of doxorubicin-loaded SLN was associated with increased drug incorporation in cells: intracellular doxorubicin levels were significantly enhanced
after exposure to drug-loaded SLN versus either free or liposomal drug. Rate of intracellular accumulation and cytotoxic activity also differed among different cell lines; in particular, cells of epithelial origin were found to be more sensitive to doxorubicin-loaded SLN. In conclusion, the
greater sensitivity of HT-29, Y79, and U373 cells to doxorubicin-loaded SLN than to the other drug formulations may be due to the capability of the delivery system to enhance drug action, through a marked uptake and accumulation of SLN within the cell.
Characterization of Polymeric Micelles for Pulmonary Delivery of Beclomethasone Dipropionate
Authors: Gaber Nazar Noureen , Darwis Yusrida , Peh Kok-Khiang , Tan Yvonne Tze-Fung
Published: September 2006

The potential of using poly-(ethylene oxide)-block-distearoyl phosphatidyl-ethanolamine (mPEG-DSPE) polymer to prepare BDP-loaded micelles with high entrapment efficiency and mass median aerodynamic diameter of less than 5 μm demonstrating sustained release properties was
evaluated. The result showed that lyophilized BDP-loaded polymeric micelles with entrapment efficiency of more than 96% could be achieved. Entrapment efficiency was affected by both the drug to polymer molar ratio and the amount of drug used. Investigation using FTIR and DSC confirmed that
there was no chemical or physical interaction and the drug was molecularly dispersed within the micelles. TEM images showed that the drug-loaded polymeric micelles were spherical in shape with multivesicular morphology. Further analysis by photon correlation spectroscopy indicated that the
particle size of the BDP-loaded micelles was about 22 nm in size. In vitro drug release showed a promising sustained release profile over six days following the Higuchi model. The mass median aerodynamic diameter and fine particle fraction were suitable for pulmonary delivery. Moreover,
the small amount of deposited drug in the induction port (throat deposition) suggested possible reduction in incidence of oropharyngeal candidiasis, a side effect normally associated with inhaled corticosteroids therapy. The high encapsulation efficiency, comparable inhalation properties,
sustained release behavior together with biocompatibility nature of the polymer support the potential of BDP-loaded polymeric micelles as a versatile delivery system to be used in the treatment of asthma and chronic obstructive pulmonary disease.
Chitosan Nanocapsules as Carriers for Oral Peptide Delivery: Effect of Chitosan Molecular Weight and Type of Salt on the In Vitro Behaviour and In Vivo Effectiveness
Authors: Prego C. , Torres D. , Alonso M. J.
Published: September 2006

We have recently reported preliminary data showing the efficacy of chitosan nanocapsules as carriers for oral peptide delivery. In the present work, our aim was to investigate the influence of some chitosan properties, such as the molecular weight and type of salt, on the interaction
of these nanocapsules with the Caco-2 cells and also on their in vivo effectiveness. Chitosan nanocapsules were prepared by the solvent displacement technique using high (450 kDa) and medium (160 kDa) molecular weight chitosan glutamate as well as high molecular weight chitosan hydrochloride
(270 kDa). The results indicated that the size of the nanocapsules was dependent on the chitosan molecular weight, whereas the zeta potential and the association efficiency of salmon calcitonin were not affected by the chitosan properties. Upon incubation with the Caco-2 cells, chitosan nanocapsules
exhibited a dose-dependent cellular viability, which was hardly affected by, either the chitosan molecular weight or, the type of salt. In addition, it was observed that the transepithelial electrical resistance of the Caco-2 monolayer was not significantly modified upon their exposure to
chitosan nanocapsules. The results of the in vivo studies, following oral administration to rats, indicated that chitosan nanocapsules were able to reduce significantly the serum calcium levels, and to prolong this reduction for at least 24 hours, irrespective of the type of chitosan
salt and molecular weight of chitosan. Consequently, the performance of chitosan nanocapsules as oral carriers for salmon calcitonin was not affected by the characteristics of chitosan.
Hemocompatibility of Layer-by-Layer Hyaluronic Acid/Heparin Nanostructure Coating on Stainless Steel for Cardiovascular Stents and its Use for Drug Delivery
Authors: Huang Li-Ying , Yang Ming-Chien
Published: September 2006

In order to develop drug-eluting cardiovascular stents, stainless steel (SUS316L) sheets were coated with hyaluronic acid (HA) and heparin (HEP), and their in vitro characteristics and drug release pattern were investigated. The surface of stainless steel (SS) was treated with
nitric acid and followed by anchoring aminotrimethoxysilane (ATMS), then a nanolayer of HA was covalently immobilized onto the surface. Heparin was then covalently bonded to the HA-immobilized SS substrate. After repeating 1 to 5 cycles, 1 to 5 layers polyelectrolyte complex (PEC) nanobrush
of HA/HEP were resulted with the thickness ranging from 280 to 630 nm (measured with ellipsometry). A model drug (sirolimus) was loaded in the HA/HEP layers at a density ranging from 1.02 to 3.12 μg/cm2. The SS-ATMS-HA-HEP substrates were evidenced by X-ray photoelectron
spectroscope (XPS), contact angle, and AFM measurement. The effect of this surface modification on the coagulation time of the resulting SS substrates was investigated. The results show that the multilayer HA/HEP stainless steel would exhibit higher anticoagulant activity than pure SS substrates.
In addition, the results of the in vitro drug delivery study showed that release of sirolimus from the 5-layer-HA-HEP stainless steel was able to maintain more than 30 days. Thus layer-by-layer HA/HEP PEC can improve the hemocompatibility of SS surface and control the drug released
rate by multiple layers of HA/HEP PEC. These results indicate that the multi-layer HA/HEP PEC coated stainless steel would be suitable for drug eluting stents.
Receptor-Mediated Gene Delivery into Antigen Presenting Cells Using Mannosylated Chitosan/DNA Nanoparticles
Authors: Kim Tae Hee , Nah Jae Woon , Cho Myung-Haing , Park Tae Gwan , Cho Chong Su
Published: September 2006

Dendritic cells (DCs) are professional antigen presenting cells that induce, sustain, and regulate immune responses. Gene modification of DCs is of particular interest for immunotherapy of diseases where the immunes system has failed or is abnormally regulated, such as in cancer or
autoimmune disease. Gene transfer using non-viral vectors is a promising approach for the safe delivery of therapeutic DNA. Among various non-viral vectors, chitosan is considered to be a good candidate for gene delivery system, however, lack of cell specificity and low transfection of chitosan
need to be overcome prior to clinical use. In this study, mannosylated chitosan (MC) was prepared to induce the receptor-mediated endocytosis and targeting into antigen presenting cells (APCs), especially DCs having mannose receptors. MC showed great ability to form complexes with DNA and
showed suitable physicochemical properties for gene delivery system. It had low cytotoxicity and exhibited much enhanced gene transfer efficiency on the macrophage cell line than chitosan itself. Also, MC/DNA complex was more efficient for transferring IL-12 gene into DCs rather than water-soluble
chitosan (WSC)/DNA one, which resulted in better induction of INF-γ from DCs. Therefore, MC is a promising gene delivery system for repeated administration to maintain sustained gene expression, thereby opening the possibility for immunotherapy.
Thermosensitive Nanocontainers Prepared from Poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-Poly(lactide)
Authors: Zhang Yan , Yang Wuli , Wang Changchun , Wu Wei , Fu Shoukuan
Published: September 2006

Thermally-responsive graft copolymer of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-poly(lactide) was synthesized by ring-opening polymerization of D,L-lactide (LA). The polymerization was initiated by the hydroxy group of poly(N-isopropyl acrylamide-co-N-(hydroxylmethyl)acrylamide),
using stannous octoate as catalyst. The resulting polymer was temperature-sensitive and the lower critical solution temperature (LCST) was affected by their composition. The chemical structure and physical properties of the grafted copolymers were investigated by various methods. Nanocontainers
formed from the self-assembly of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl) acrylamide)-g-poly(lactide) were characterized by transmission electron microscopy (TEM), and a spherical structure was observed. Dynamic light scattering (DLS) results indicate that the particle size increased
with the increase of polylactide content in the copolymer. The properties of this polymer are interesting for both industrial application and fundamental research. In particular it will combine a spatial specificity in a passive manner and a temperature-responsive active targeting mechanism
for drug delivery system.
Freeze-Drying of Low Molecular Weight Poly(L-lactic acid) Nanoparticles: Effect of Cryo- and Lyoprotectants
Authors: Hirsjärvi Samuli , Peltonen Leena , Kainu Laura , Hirvonen Jouni
Published: September 2006

The chemical and physical stability of polymeric nanoparticles is poor in aqueous suspensions, and the drying of these particles is often problematic. In the present study, the stability of freeze-dried low molecular weight poly(L-lactic acid) (PLA) nanoparticles was enhanced by adding
glucose and/or lactose to the formulation as cryo- and lyoprotectants, respectively. Also the effect of an extra stabilizer, Tween 80, was studied. The best freeze-dried PLA nanoparticle formulations were achieved, when glucose and lactose were added in combination so that the amount of lactose
was double the amount of glucose. With this combination the redispersion of high-quality nanoparticles (homogenous particle dispersion with original size and without aggregates) was achieved. The addition of Tween 80 further improved the quality of freeze-dried PLA nanoparticles by facilitating
the redispersion of the lyophilized cake into optimal nanoparticles.
Nanoparticles for Cellular Drug Delivery: Mechanisms and Factors Influencing Delivery
Authors: Chavanpatil Mahesh D. , Khdair Ayman , Panyam Jayanth
Published: September 2006

Polymeric nanoparticles have demonstrated enormous potential as cellular drug delivery vehicles. Nanoparticles improve drug's stability as well as its availability and retention at the target intracellular site of action. Therapeutic efficacy of nanoparticles can be further enhanced
by conjugating specific ligands to nanoparticle surface. Ligand conjugation can also be used to favorably modify the intracellular disposition of nanoparticles. A number of ligands are available for this purpose; use of a specific ligand depends on the target cell, the material used for nanoparticle
formulation, and the chemistry available for ligand-nanoparticle conjugation. Cellular drug delivery using nanoparticles is also affected by clearance through the reticuloendothelial system. In this paper, we review the recent progress on our understanding of physicochemical factors that affect
the cellular uptake of nanoparticles and the different cellular processes that could be exploited to enhance nanoparticle uptake into cells.
Anodization: A Promising Nano-Modification Technique of Titanium Implants for Orthopedic Applications
Authors: Yao Chang , Webster Thomas J.
Published: September 2006

Anodization is a well-established surface modification technique that produces protective oxide layers on valve metals such as titanium. Many studies have used anodization to produce micro-porous titanium oxide films on implant surfaces for orthopedic applications. An additional hydrothermal
treatment has also been used in conjunction with anodization to deposit hydroxyapatite on titanium surfaces; this is in contrast to using traditional plasma spray deposition techniques. Recently, the ability to create nanometer surface structures (e.g., nano-tubular) via anodization of titanium
implants in fluorine solutions have intrigued investigators to fabricate nano-scale surface features that mimic the natural bone environment. This paper will present an overview of anodization techniques used to produce micro-porous titanium oxide structures and nano-tubular oxide structures,
subsequent properties of these anodized titanium surfaces, and ultimately their in vitro as well as in vivo biological responses pertinent for orthopedic applications. Lastly, this review will emphasize why anodized titanium structures that have nanometer surface features enhance
bone forming cell functions.
Polymeric Nanostructures for Drug Delivery Applications Based on Pluronic Copolymer Systems
Authors: Xiong X. Y. , Tam K. C. , Gan L. H.
Published: September 2006

The first part of this article reviewed the applications of nanostructures derived from Pluronic block copolymers that have potentials in the field of biomedical sciences. Pluronic block copolymers are used not only in drug delivery systems but also in gene and cancer therapies. In
the second part, the chemical modifications of Pluronic copolymers and their applications in biomedical science were reviewed. Chemical modifications of Pluronic copolymers not only improve the properties of the polymers but they also impart more attractive properties to the block copolymers.
The common systems used to modify Pluronic copolymers are polyacrylic acids, polybases, and biodegradable polyesters. Pluronics were also modified at both ends with functional groups to improve the mechanical properties of hydrogels.
Characterizing Poly(ε-caprolactone)-b-Chitooligosaccharide-b-Poly(ethylene glycol) (PCP) Copolymer Micelles for Doxorubicin (DOX) Delivery: Effects of Crosslinked of Amine Groups
Authors: Chung Tze-Wen , Liu Der-Zen , Hsieh Jui-Hsiang , Fan Xian-Chan , Yang Jean-Dean , Chen Jui-Hsiang
Published: September 2006

New amine-groups containing tri-block copolymers and micelles that consisting of poly(ε-caprolactone)-b-chitooligosaccharide-b-poly(ethylene glycol) (PCL-b-COS-b-PEG, PCP), were synthesized, characterized, and evaluated for delivering doxorubicin (DOX) with or without crosslinked
amine groups by genipin. The characteristics of the PCP copolymers of Fourier-transform infrared spectrometry (FT-IR) verify the amine and ester groups of the COS and the PCL of the copolymers, respectively. 1H nuclear magnetic resonance (1H NMR) spectra verify the structures
of the PCP copolymers consisting two PCL and PEG polymers reacted onto the COS block. In addition, gel permeation chromatography (GPC) determines the number average molecular weight of the triblock copolymers (Mn) of approximately 11340 Da/mole. The PCP copolymers can self-assemble
to form polymeric micelles at the critical micelle concentration (CMC) of 1.0 μM as determined by the UV-VIS absorption spectra. The mean diameter of the PCP micelles is 90 nm, as determined using a dynamic light-scattering (DLS) analyzer. Moreover, the zeta potentials of PCP micelles
change from neutral to cationic state when pH of suspension mediums varied from 7.4 to 3.0. For evaluating delivery characteristics of hydrophobic DOX, it was loaded into PCP micelles with or without crosslinked by genipin. The burst release and release period of DOX for the crosslinked micelles
are significantly reduced (P < 0.003, n = 3, for pH = 7.4) and sustained (e.g., 8 days), respectively, than those non-crosslinked ones (e.g., 4 days). In conclusion, new tri-block amine groups containing PCP copolymers are synthesized that can self-assemble as PCP micelles.
After post-crosslinked amine groups of DOX loaded the micelles, they can effectively reduce the burst release and sustain the release of DOX at different pH dissolution mediums. Further applications of PCP copolymers and micelles for drug delivery can be explored in future.
Thymopentin-Loaded pH-Sensitive Chitosan Nanoparticles for Oral Administration: Preparation, Characterization, and Pharmacodynamics
Authors: Zheng Ai-Ping , Wang Jian-Cheng , Lu Wan-Liang , Zhang Xuan , Zhang Hua , Wang Xue-Qing , Zhang Qiang
Published: September 2006

Thymopentin, a potent immunomodulating drug, was incorporated into pH-sensitive chitosan nanoparticles prepared by ionic gelation of chitosan with tripolyphosphate anions and then coated with Eudragit S100 to improve the stability and the oral bioavailability. Nanoparticles particle
size and zeta potential were measured by photo correction spectroscopy and laser Dopper anemometry. Its morphology was examined by environment scan electron microscope. The encapsulation efficiency and the release in vitro were determined by HPLC. Enzymatic stabilization was expressed
by the enzymatic degradation of aminopeptidase. Biological activity of TP5 loaded in nanoparticles was assayed by lymphocyte proliferation test in vitro and the immune function (CD4+/CD8+) of irradiated rat in vivo. The results obtained demonstrated that the average sizes of
pH-sensitive chitosan nanoparticles were 175.6 ± 17 nm, the zeta potential was 28.44 ± 0.5 mV and the encapsulation efficiency was 76.70 ± 2.6%. The cumulative release percentages of thymopentin from the pH-sensitive nanoparticles were 24.65%, 41.01%, and 81.44% incubated
in different medium, 0.1 N HCl, pH 5.0 PBS, and pH 7.4 PBS, respectively. The pH-sensitive chitosan nanoparticles could efficiently protect TP5 from enzymatic degradation and prolong the degradation half-time of TP5 from 1.5 min to 15 min. It was demonstrated from the lymphocyte proliferation
test that the nanoparticle-encapsulated TP5 still kept its biological activity. In immunosuppression rats, the lowered T-lymphocyte subsets values were significantly increased and the raised CD4+/CD8+ ratio was evidently reduced. These results indicated that pH-sensitive chitosan nanoparticles
may be used as the vector in oral drug delivery system for TP5.
Lyoprotected Nanosphere Formulations for Paclitaxel Controlled Delivery
Authors: Musumeci T. , Vicari L. , Ventura C. A. , Gulisano M. , Pignatello R. , Puglisi G.
Published: September 2006

The preparation and technological characterization of nanosphere formulations (NS) containing the anticancer drug paclitaxel (PTX) are reported. Poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) nanospheres (NS) were prepared by a solvent displacement method. They showed
a mean particle size in the range 150–300 nm, with a high homogeneity (polydispersity index <0.3). For long term stability, NS require additional procedures, such as freeze-drying. In this study, the effect on NS particle size and surface charge of different lyoprotectants (mono-
and disaccharides, polyalcohols, and hydroxypropyl-ß-cyclodextrin) at various concentrations was tested by means of light scattering size analysis. The formulations freeze-dried with the addition of 10% glucose (w/v) showed interesting characteristics after freeze-drying. They were chosen
for specific studies on drug encapsulation efficiency, in vitro drug release and biological activity on the human anaplastic thyroid carcinoma cell line 8305C. The PLGA NS, in particular, showed a cell growth inhibitory activity comparable to the free drug.
Polymer-Based Nanoparticles for the Delivery of Nucleoside Analogues
Authors: Hillaireau Hervé , Le Doan Trung , Couvreur Patrick
Published: September 2006

Nucleoside analogues, together with nucleobases and nucleotide analogues, are commonly used in the treatment of cancer and viral infections. In both cases, they act as antimetabolite agents and interfere with the synthesis of cellular or viral nucleic acids. However, the need of high
doses due to the rapid elimination of these compounds, to their poor activation, and/or to their non-specific distribution, often leads to side effects and resistances. The present paper aims to review the different types of polymer nanoparticles which have been designed as drug delivery devices
to address these issues. Thus, poly(alkylcyanoacrylate) nanoparticles have been demonstrated as potential carriers for antiviral nucleoside analogues, especially for anti-HIV agents, regarding both intravenous and oral routes. Nanoparticles based on polyesters such as poly(lactic acid) and
poly(lactide-co-glycolide) have been used as nanocarriers for nucleosides analogues too, and especially for their ocular delivery. Albumin has shown interesting properties in the design of nanoparticles for the same application, but also for the oral administration of anticancer analogues.
Finally, new hydrophilic nanoparticles consisting of cross-linked polymer network ('Nanogels') open the perspective to deliver nucleoside analogues within their active triphosphate form.
Gliadin Characterization by Sans and Gliadin Nanoparticle Growth Modelization
Authors: Orecchioni Anne-Marie , Duclairoir Cécile , Renard Denis , Nakache Evelyne
Published: September 2006

Nanosized colloidal carriers can ensure a controlled and targeted therapeutic substances delivery. The original contribution of this work was to use biopolymers of vegetable source, which are an interesting alternative to synthetic polymers. The aim of this study was to prepare submicronic
particles from wheat proteins: Gliadins extracted from gluten. The carrier preparation was based on the desolvatation of the macromolecules by a couple solvent/non-solvent of the proteins. In a first step, it was of interest to elucidate the gliadin macromolecular conformation in order to
understand the mechanism of nanoparticle formation. The experimental work was based on SANS experiments. Because the size of the colloidal particle suspension is an important parameter to monitor, the modelization of the particle growth was thoroughly studied. Furthermore, it was observed
that the determination of the solubility parameters of the proteins allowed optimization of the size of the particles. From those previous experimental results it can be concluded that there is a correlation between the protein conformation in the solvent and the size of the nanoparticles
(NP).
Nanotechnologies in Protein Delivery
Authors: Salmaso Stefano , Bersani Sara , Semenzato Alessandra , Caliceti Paolo
Published: September 2006

The growth rate for biotech drugs, namely proteins, peptides, and oligonucleotides, is dictated by the parallel progresses in biotechnology and nanotechnology. Actually, biotechnology techniques have expanded enormously the arsenal of therapeutically useful peptides and proteins making
these products of primary interest for future pharmaceutical market. Nevertheless, the exploitation of protein and peptide drugs is strictly related to the development of innovative delivery systems which should provide for controlled, prolonged, or targeted delivery, improved stability during
storage and delivery, reduced adverse effects, increased bioavailability, improved patient compliance and allow for administration through the desired route and cope with cost-containment therapeutic protocols. Colloidal formulations ideally possess the physicochemical and biopharmaceutical
requisites for protein delivery. Pharmaceutical nanotechnology is a tool of techniques applied to design, develop and produce these systems. It involves the investigation of innovative materials and production procedures for preparation of a variety of nanosized dosage forms, which range from
solid nanoparticles to soluble bioconjugates. The research and development of innovative tailor made protein delivery systems, which must be designed according to the drug candidate pharmacological and physicochemical properties, is one of the primary aim of modern pharmaceutical technology.
Therefore, as an unmet need exists for technologies that combine innovative drug delivery solutions, a close un-prejudicial interaction between academic and industrial researchers as well as business thought leaders is required.