ABSTRACT
BACKGROUND: Women with stress urinary incontinence (SUI) experience urine leakage with physical activity. Currently, the interventional treatments for SUI are surgical, or endoscopic bulking injection(s). However, these procedures are not always successful, and symptoms can persist or come back after treatment, categorised as recurrent SUI. There are longstanding symptoms and distress associated with a failed primary treatment, and currently, there is no consensus on how best to treat women with recurrent, or persistent, SUI. METHODS: A two-arm trial, set in at least 20 National Health Service (NHS) urology and urogynaecology referral units in the UK, randomising 250 adult women with recurrent or persistent SUI 1:1 to receive either an endoscopic intervention (endoscopic bulking injections) or a standard NHS surgical intervention, currently colposuspension, autologous fascial sling or artificial urinary sphincter. The aim of the trial is to determine whether surgical treatment is superior to endoscopic bulking injections in terms of symptom severity at 1 year after randomisation. This primary outcome will be measured using the patient-reported International Consultation on Incontinence Questionnaire - Urinary Incontinence - Short Form (ICIQ-UI-SF). Secondary outcomes include assessment of longer-term clinical impact, improvement of symptoms, safety, operative assessments, sexual function, cost-effectiveness and an evaluation of patients' and clinicians' views and experiences of the interventions. DISCUSSION: There is a lack of high-quality, randomised, scientific evidence for which treatment is best for women presenting with recurrent SUI. The PURSUIT study will benefit healthcare professionals and patients and provide robust evidence to guide further treatment and improve symptoms and quality of life for women with this condition. TRIAL REGISTRATION: International Standard Randomised Controlled Trials Number (ISRCTN) registry ISRCTN12201059. Registered on 09 January 2020.
Subject(s)
Urinary Incontinence, Stress , Urinary Incontinence , Urinary Sphincter, Artificial , Adult , Female , Humans , Quality of Life , State Medicine , Treatment Outcome , Urinary Incontinence/diagnosis , Urinary Incontinence/surgery , Urinary Incontinence, Stress/diagnosis , Urinary Incontinence, Stress/surgeryABSTRACT
BACKGROUND: Foam sclerotherapy is the process of using an aqueous foam to deliver surfactant to a varicose vein to damage vein wall endothelial cells, causing the vein to spasm, collapse and ultimately be re-absorbed into the body. Aqueous foams are complex fluids that can exhibit a significant yield stress and high effective viscosity which depend on their composition, particularly the bubble size and liquid fraction. OBJECTIVE: To characterise the properties of foams used for varicose vein sclerotherapy and determine their effectiveness in the displacement of blood during sclerotherapy. METHODS: Foams are modelled as yield stress fluids and their flow profiles in a model vein are predicted. Values of the yield stress are determined from experimental data for three different foams using the Sauter mean of the bubble size distribution. Along with the measured liquid fraction of the foams, this information is collected into a Bingham number which entirely characterises the process of sclerotherapy. RESULTS: Polydispersity in bubble size has a strong effect on the yield stress of a foam and the Sauter mean of the size distribution better captures the effects of a few large bubbles. Reducing the polydispersity increases the yield stress, and a higher yield stress results in a larger plug region moving along the vein, which is more effective in displacing blood. The width of the plug region is proportional to the Bingham number, which also has a quadratic dependence on the liquid fraction of the foam. Assuming typical values for the rate of injection of a foam, we predict that for a vein of diameter 5 mm, the most effective foams have low liquid fraction, a narrow size distribution, and a Bingham number B ≈ 4.5. CONCLUSIONS: The Sauter mean radius provides the most appropriate measure of the bubble size for sclerotherapy and the Bingham number then provides a simple measure of the efficacy of foam sclerotherapy in a vein of a given size, and explains the ability of different foams to remove varicose veins. Foams containing small bubbles, with a narrow size distribution, and a low liquid fraction are beneficial for sclerotherapy.
Subject(s)
Sclerotherapy , Varicose Veins , Endothelial Cells , Humans , Polidocanol , Polyethylene Glycols , Sclerosing Solutions/therapeutic use , Varicose Veins/drug therapyABSTRACT
Guidelines suggest that very-low-energy diets (VLEDs) should be used to treat obesity only when rapid weight loss is clinically indicated because of concerns about rapid weight regain. Literature databases were searched from inception to November 2014. Randomized trials were included where the intervention included a VLED and the comparator was no intervention or an intervention that could be given in a general medical setting in adults that were overweight. Two reviewers characterized the population, intervention, control groups, outcomes and appraised quality. The primary outcome was weight change at 12 months from baseline. Compared with a behavioural programme alone, VLEDs combined with a behavioural programme achieved -3.9 kg [95% confidence interval (CI) -6.7 to -1.1] at 1 year. The difference at 24 months was -1.4 kg (95%CI -2.6 to -0.2) and at 38-60 months was -1.3 kg (95%CI -2.9 to 0.2). Nineteen per cent of the VLED group discontinued treatment prematurely compared with 20% of the comparator groups, relative risk 0.96 (0.56 to 1.66). One serious adverse event, hospitalization with cholecystitis, was reported in the VLED group and none in the comparator group. Very-low-energy diets with behavioural programmes achieve greater long-term weight loss than behavioural programmes alone, appear tolerable and lead to few adverse events suggesting they could be more widely used than current guidelines suggest.
Subject(s)
Caloric Restriction , Obesity/diet therapy , Weight Loss , Blood Glucose/metabolism , Cholesterol, HDL/blood , Cholesterol, LDL/blood , Databases, Factual , Diet, Reducing , Fasting , Humans , Insulin/blood , Randomized Controlled Trials as Topic , Sensitivity and Specificity , Treatment OutcomeABSTRACT
BACKGROUND: Lower urinary tract symptoms (LUTS) comprise storage symptoms, voiding symptoms and post-voiding symptoms. Prevalence and severity of LUTS increase with age and the progressive increase in the aged population group has emphasised the importance to our society of appropriate and effective management of male LUTS. Identification of causal mechanisms is needed to optimise treatment and uroflowmetry is the simplest non-invasive test of voiding function. Invasive urodynamics can evaluate storage function and voiding function; however, there is currently insufficient evidence to support urodynamics becoming part of routine practice in the clinical evaluation of male LUTS. DESIGN: A 2-arm trial, set in urology departments of at least 26 National Health Service (NHS) hospitals in the United Kingdom (UK), randomising men with bothersome LUTS for whom surgeons would consider offering surgery, between a care pathway based on urodynamic tests with invasive multichannel cystometry and a care pathway based on non-invasive routine tests. The aim of the trial is to determine whether a care pathway not including invasive urodynamics is no worse for men in terms of symptom outcome than one in which it is included, at 18 months after randomisation. This primary clinical outcome will be measured with the International Prostate Symptom Score (IPSS). We will also establish whether inclusion of invasive urodynamics reduces rates of bladder outlet surgery as a main secondary outcome. DISCUSSION: The general population has an increased life-expectancy and, as men get older, their prostates enlarge and potentially cause benign prostatic obstruction (BPO) which often requires surgery. Furthermore, voiding symptoms become increasingly prevalent, some of which may not be due to BPO. Therefore, as the population ages, more operations will be considered to relieve BPO, some of which may not actually be appropriate. Hence, there is sustained interest in the diagnostic pathway and this trial could improve the chances of an accurate diagnosis and reduce overall numbers of surgical interventions for BPO in the NHS. The morbidity, and therapy costs, of testing must be weighed against the cost saving of surgery reduction. TRIAL REGISTRATION: Controlled-trials.com - ISRCTN56164274 (confirmed registration: 8 April 2014).
Subject(s)
Lower Urinary Tract Symptoms/diagnosis , Prostatic Hyperplasia/diagnosis , Urinary Bladder Neck Obstruction/diagnosis , Urodynamics , Clinical Protocols , Diagnosis, Differential , Humans , Lower Urinary Tract Symptoms/etiology , Lower Urinary Tract Symptoms/physiopathology , Lower Urinary Tract Symptoms/surgery , Male , Predictive Value of Tests , Prognosis , Prostatectomy , Prostatic Hyperplasia/complications , Prostatic Hyperplasia/physiopathology , Prostatic Hyperplasia/surgery , Research Design , Surveys and Questionnaires , Time Factors , United Kingdom , Unnecessary Procedures , Urinary Bladder Neck Obstruction/etiology , Urinary Bladder Neck Obstruction/physiopathology , Urinary Bladder Neck Obstruction/surgeryABSTRACT
BACKGROUND: Regular weighing in pregnant women is not currently recommended in many countries but has been suggested to prevent excessive gestational weight gain. This study aimed to establish the feasibility and acceptability of incorporating regular weighing, setting maximum weight gain targets and feedback by community midwives. METHODS: Low risk pregnant women cared for by eight community midwives were randomised to usual care or usual care plus the intervention at 10-14 weeks of pregnancy. The intervention involved community midwives weighing and plotting weight on a weight gain chart, setting weight gain limit targets, giving brief feedback at each antenatal appointment and encouraging women to weigh themselves weekly between antenatal appointments. Women and midwives were interviewed about their views of the intervention. The focus of the study was on process evaluation. RESULTS: Community midwives referred 123 women and 115 were scheduled for their dating scan within the study period. Of these, 84/115 were approached at their dating scan and 76/84 (90.5 %) randomised. Data showed a modest difference favouring the intervention group in the percentage of women gaining excessive gestational weight (23.5 % versus 29.4 %). The intervention group consistently reported smaller increases in depression and anxiety scores throughout pregnancy compared with usual care. Most women commented the intervention was useful in encouraging them to think about their weight and believed it should be part of routine antenatal care. Community midwives felt the intervention could be implemented within routine care without adding substantially to consultation length, thus not perceived as adding substantially to their workload. CONCLUSIONS: The intervention was feasible and acceptable to pregnant women and community midwives and was readily implemented in routine care. TRIAL REGISTRATION: ISRCTN81605162.
ABSTRACT
With the aid of stimulus-responsive hydrogel substrates composed of ABA triblock copolymer micelles, we monitored the morphological dynamics of myoblast (C2C12) cells in response to an abrupt change in the substrate elasticity by live cell imaging. The remodeling of actin cytoskeletons could be monitored by means of transient transfection with LifeAct-GFP. Dynamic changes in the orientational order of actin filaments were characterized by an order parameter, which enables one to generalize the mechanically induced actin cytoskeletons as a break of symmetry. The critical role that acto-myosin complexes play in the morphological transition was verified by the treatment of cells with myosin II inhibitor (blebbistatin) and the fluorescence localization of focal adhesion contacts. Such dynamically tunable hydrogels can be utilized as in vitro cellular micro-environments that can exert time-dependent stimuli to mechanically regulate target cells.
Subject(s)
Actin Cytoskeleton/chemistry , Myoblasts/chemistry , Myosin Type II/chemistry , Actin Cytoskeleton/metabolism , Cell Adhesion , Cell Line , Cell Tracking , Elasticity , Myoblasts/cytology , Myosin Type II/metabolism , Optical Imaging , TransfectionABSTRACT
BACKGROUND: Many pregnant women gain excess weight during pregnancy which increases the health risks to the mother and her baby. Interventions to prevent excess weight gain need to be given to the whole population to prevent excess weight gain. The aim of this study was to assess the effectiveness of a simple and brief intervention embedded withinroutine antenatal care to prevent excessive gestation weight gain. METHODS: Six hundred and ten pregnant women (between 10-14 weeks gestation), aged ≥18 years with a body mass index (BMI) ≥18.5 kg/m2, planned to receive community midwife led care or shared care at the time of recruitment are eligible to take part in the study. Women will be recruited from four maternity centres in England. Community midwives complete a short training module before delivering the intervention. In the intervention, midwives weigh women, set maximum weight limits for weight gain at each antenatal appointment and ask women to monitor their weight at home. Themaximum weight limit is adjusted by the midwife at each antenatal appointment if women have exceeded their maximum weight gain limit set at their previous appointment. The intervention will be compared with usual antenatal care. The primary outcome is the proportion of women per group who exceed the Institute of Medicine guidelines for gestational weight gain at 38 weeks of pregnancy according to their early pregnancy BMI category. DISCUSSION: The proposed trial will test a brief intervention comprising regular weighing, target setting and monitoring ofweight during pregnancy that can be delivered at scale as part of routine antenatal care. Using the professional expertise of community midwives, but without specialist training in weight management, the intervention will incur minimal additionalhealthcare costs, and if effective at reducing excess weight gain, is likely to be very cost effective. TRIAL REGISTRATION: Current controlled trials ISRCTN67427351. Date assigned 29/10/2014.
ABSTRACT
PURPOSE: CriticalSorb™ is a novel absorption enhancer based on Solutol(®) HS15, one that has been found to enhance the nasal transport. It is in clinical trials for nasal delivery of human growth hormone. The hypothesis was that permeating enhancement effects of the Solutol(®)HS15 component would translate to the intestine. METHODS: Rat colonic mucosae were mounted in Ussing chambers and Papp values of [(14)C]-mannitol, [(14)C]-antipyrine, FITC-dextran 4000 (FD-4), and TEER values were calculated in the presence of CriticalSorb™. Tissues were fixed for H & E staining. Caco-2 monolayers were grown on Transwells™ for similar experiments. RESULTS: CriticalSorb™(0.01% v/v) significantly increased the Papp of [(14)C]-mannitol, FD-4 [(14)C]-antipyrine across ileal and colonic mucosae, accompanied by a decrease in TEER. In Caco-2 monolayers, it also increased the Papp of [(14)C]-mannitol FD-4 and [(14)C]-antipyrine over 120 min. In both monolayers and tissues, it acted as a moderately effective P-glycoprotein inhibitor. There was no evidence of cytotoxicity in Caco-2 at concentrations of 0.01% for up to 24 h and histology of tissues showed intact epithelia at 120 min. CONCLUSIONS: Solutol(®) HS15 is the key component in CriticalSorb™ that enables non-cytotoxic in vitro intestinal permeation and its mechanism of action is a combination of increased paracellular and transcellular flux.
Subject(s)
Intestinal Mucosa/metabolism , Animals , Caco-2 Cells , Humans , Male , Rats , Rats, WistarABSTRACT
INTRODUCTION: Chemotherapeutic drug-eluting beads (DEBs) are microspheres that are in clinical use for intraarterial chemoembolisation of liver cancer. Here we report on the biocompatibility and anti-tumour efficacy of DEBs after intratumoral application in a rat BT4Ca glioma model. METHODS AND RESULTS: Doxorubicin and irinotecan-eluting DEBs were suspended in a Ca(2+)-free aqueous alginate solution that provides a sol-gel transition when injected into the Ca(2+) rich brain tissue. In this way the DEBs are immobilised at the implantation site. Forced elution studies in vitro using a USP-4 flow-through apparatus demonstrated that the alginate excipient helped to reduce the burst effect and rate the elution from the beads. From the in vivo evaluation, doxorubicin DEBs demonstrated a significant local toxicity, while irinotecan-loaded DEBs showed good local tissue compatibility. Doxorubicin at higher concentrations and irinotecan-loaded DEBs were found to decrease tumour volume, increase survival time and decrease the Ki67 proliferation index of the tumour. Doxorubicin was shown by fluorescent microscopy to diffuse into the peritumoral tissue, but also penetrates along white matter tracts, to more distant areas. DISCUSSION: We conclude that the alginate suspension of irinotecan DEBs can be considered safe and effective in a clinical setting (AU)
Subject(s)
Animals , Male , Female , Rats , Alginates/chemistry , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Brain Neoplasms/drug therapy , Tumor Burden , Glioma/drug therapy , Microspheres , Drug Delivery Systems , Materials Testing , Brain Neoplasms/mortality , Brain Neoplasms/pathology , Camptothecin/analogs & derivatives , Camptothecin/administration & dosage , Doxorubicin/administration & dosage , Glioma/mortality , Glioma/pathology , Glucuronic Acid/chemistry , Hexuronic Acids , Survival RateABSTRACT
OBJECTIVE Previous research in a rat glioma model has shown that the local intratumoral application of polymerbased drug-eluting beads (DEBs) loaded with doxorubicin or irinotecan suppress tumour growth and prolong survival. For translation into a clinical setting, the present experiment investigates in the healthy cat brain the local and systemic toxicity of a multiple injection shot technique. METHODS Three injection shots were placed, each at a 1 cm distance in the frontal lobe. The DEBs were suspended in an aqueous alginate excipient solution, which becomes subject to a sol-gel transition when injected into the Ca(2+)- rich brain tissue environment. Systemic and local side effects were monitored over a period of two weeks. Injection sites were histologically investigated. RESULTS Gelling of the alginate results in the permanent immobilisation of the microspheres at the implantation site. A distinct local cytotoxic effect of doxorubicin was found with intracerebral and intraventricular haemorrhages, and signs of brain tissue necrosis. In cats injected with irinotecan DEBs, such local adverse side effects did not occur. No signs of systemic toxicity were found with both chemotherapeutics. DISCUSSION We conclude that the multiple injection shot technique with irinotecan DEBs meets feasibility criteria and safety requirements for a clinical application.
Subject(s)
Antibiotics, Antineoplastic/therapeutic use , Antineoplastic Agents, Phytogenic/therapeutic use , Camptothecin/analogs & derivatives , Doxorubicin/therapeutic use , Glioma/drug therapy , Microspheres , Animals , Brain Neoplasms/drug therapy , Brain Neoplasms/pathology , Camptothecin/therapeutic use , Cats , Female , Glioma/pathology , Infusion Pumps, Implantable , Injections, Intraventricular , Irinotecan , Male , Necrosis , Safety , Treatment OutcomeABSTRACT
Single shot vaccines of tetanus toxoid (TT) were manufactured using the NanoMix process - a low temperature solvent free encapsulation technology using supercritical fluids. The formulations were injected into mice, and compared to multiple injections of a commercially available alum adsorbed TT vaccine. After 5 months the antibody titres were found to be similar for both the alum adsorbed and microparticle formulations, demonstrating for the first time the potential of formulating antigens in PLA microparticles using the supercritical fluid (NanoMix) technique to produce single shot vaccines. The results are likely to be due to the maintenance of toxoid bioactivity and some degree of sustained release of the encapsulated antigens, resulting in repeated stimulation of antigen presenting cells eliminating the need for multiple immunisations. This demonstrates the potential of this supercritical fluid processing technique to reduce the need for booster doses in a vaccine regimen.
Subject(s)
Drug Compounding/methods , Drug Delivery Systems , Tetanus Toxoid/administration & dosage , Tetanus Toxoid/chemistry , Adjuvants, Immunologic/administration & dosage , Alum Compounds , Animals , Control Groups , Delayed-Action Preparations , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Carriers , Female , Immunization , Lactic Acid/chemistry , Mice , Mice, Inbred BALB C , Particle Size , Placebos , Polyesters , Polymers/chemistry , Tetanus/immunology , Tetanus Toxoid/immunology , Vaccines/administration & dosage , Vaccines/chemistry , Vaccines/immunologyABSTRACT
Folic acid has been investigated as a targeting ligand for imaging and therapeutic agent for over a decade; however, studies on its use in targeting of nonviral gene or nucleic acids delivery systems are sparse. This study assesses potential application of a new folic acid conjugate with aminomethacrylate-phosphoryl-choline based copolymer (DMAEMA-MPC-FA) as a targeting gene delivery vector. The folate-conjugated polymers produce colloidally stable polyplexes with a particle size <200 nm and demonstrate the ability to protect DNA from enzymatic degradation to a certain extent. In cells that overexpress folate receptors (MCF-7 and KB cultures), the conjugated systems show a folate-specific association and achieved significantly enhanced transfection efficiency, compared to the nonconjugated control, with a dramatically reduced nonspecific cellular association. The transfection enhancement is achieved without a corresponding increase in cellular association, suggesting that an internal cellular trafficking of folate-conjugated system may be altered, resulting in an increased transfection efficacy. In summary, a new folate-conjugated aminomethacrylate-phosphorylcholine copolymer is capable of forming colloidal complexes with DNA, modulating their specific cell uptake and improving the level of cell transfection in folate expressing cells.
Subject(s)
Carrier Proteins/metabolism , DNA/administration & dosage , Folic Acid/administration & dosage , Gene Transfer Techniques , Receptors, Cell Surface/metabolism , Cations , Cell Line, Tumor , Colloids , Folate Receptors, GPI-Anchored , Folic Acid/chemistry , Genetic Vectors , Humans , KB Cells , Ligands , Methacrylates/chemistry , Particle Size , Phosphorylcholine/analogs & derivatives , Phosphorylcholine/chemistry , Polymers/chemistry , Transfection/methodsABSTRACT
We have characterized three diblock copolymers bearing zwitterionic phosphorylcholine and weak tertiary amine groups, namely, poly[((2-(methacryloyloxy)ethyl)phosphorylcholine)30- block-(2-(dimethylamino)ethyl methacrylate)60] (denoted as MPC30-DMA60, Mn=18,000), poly[((2-(methacryloyloxy)ethyl)phosphorylcholine)30- block-(2-(diethylamino)ethyl methacrylate)60) (denoted as MPC30-DEA60, Mn=20,000), and poly[((2-(methacryloyloxy)ethyl)phosphorylcholine)30- block-(2-(diisopropylamino)ethyl methacrylate)60) (denoted as MPC30-DPA60, Mn=21,000), by studying their surface tension and solution aggregation through a combined approach of surface tension measurement, dynamic light scattering, and small-angle neutron scattering. Our results show that larger tertiary amine substituents lead to an increasing tendency to form micellar aggregates, which is consistent with the increasing copolymer hydrophobicity. Thus, MPC30-DMA60 did not aggregate under the experimental conditions studied. The free chains exist in the form of thin cylinders, whose length decreases with copolymer concentration and solution temperature but increases with solution pH. The diameters of the MPC30-DMA60 cylinders remained almost constant at around 30 A under all the conditions studied. At the lower copolymer concentration of 0.5 wt %, the cylindrical lengths correspond to the persistence length of the copolymer backbone and are close to its full length, indicating a rather high rigidity. Further data analysis showed that, at the two higher concentrations of 2 and 4 wt %, the phosphorylcholine and amine blocks associate, inducing bending of the copolymer backbone. One backbone kink was required to satisfy all the constraints, including the dry volume of the copolymer. MPC30-DEA60 showed a similar trend of pH- and concentration-dependent conformational responses for the free copolymer, but in addition micellar aggregation occurred at pH 9. In contrast, MPC30-DPA60 exhibited significantly reduced solubility associated with strong aggregation, which is consistent with it being the most hydrophobic copolymer in the series.
Subject(s)
Hydrogen-Ion Concentration , Phosphorylcholine/chemistry , Polymers/chemistry , NanotechnologyABSTRACT
This two-part article considers the complexities of developing and commercialising combination products using examples from experience with drug-eluting stents and drug-eluting beads. Part I discusses the technical challenges of developing these products.
Subject(s)
Drug Delivery Systems , Equipment and Supplies , Biocompatible Materials , Drug-Eluting Stents , HumansABSTRACT
The technical challenges of developing combination products were addressed in Part I of this two part article. Part II reviews the preclinical tests and shelf-life testing that are required using drug eluting stents and drug eluting beads as examples. Regulatory considerations and ways to simplify development are also examined.
Subject(s)
Drug Delivery Systems/methods , Drug-Eluting Stents/standards , Animals , Antineoplastic Protocols , Doxorubicin/administration & dosage , Drug Delivery Systems/economics , Drug Delivery Systems/instrumentation , Drug-Eluting Stents/economics , Embolization, Therapeutic/instrumentation , Embolization, Therapeutic/methods , Equipment Design/economics , Equipment Design/standards , Equipment Failure Analysis/methods , Equipment Safety/methods , Government Regulation , Humans , Microspheres , Neoplasms/therapy , Quinolones , Validation Studies as Topic , Vascular Surgical ProceduresABSTRACT
A well-defined, double-hydrophilic diblock copolymer comprising poly[2-(methacryloyloxy)ethyl phosphorylcholine]-block-(glycerol monomethacrylate) (PMPC30-PGMA30, where the numbers represent the average degrees of polymerization for each block) was evaluated for the synthesis of colloidally stable ultrafine magnetite sols. Sterically stabilized paramagnetic sols were prepared in aqueous solution by chemical coprecipitation of ferric and ferrous salts in the presence of this block copolymer. The PMPC30-PGMA30-stabilized magnetite sol had a mean transmission electron microscopy (TEM) diameter of 9.4 +/- 1.7 nm and a mean hydrodynamic diameter of 34 nm. This sol exhibited improved colloidal stability with respect to long-term storage and pH variation compared with magnetite sols prepared in the presence of alternative water-soluble homopolymers and diblock copolymers. Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry, electron spectroscopy imaging (ESI), and zeta potential studies indicate that the PMPC30-PGMA30 diblock copolymer was adsorbed onto the surface of the sol via the PGMA30 block, with the PMPC30 chains acting as the stabilizing block. Such sterically stabilized sols are expected to be improved contrast agents for magnetic resonance imaging (MRI) applications.
Subject(s)
Coated Materials, Biocompatible/chemical synthesis , Contrast Media/chemical synthesis , Ferrosoferric Oxide/chemical synthesis , Methacrylates/chemical synthesis , Nanoparticles/chemistry , Phosphorylcholine/analogs & derivatives , Coated Materials, Biocompatible/chemistry , Contrast Media/chemistry , Ferrosoferric Oxide/chemistry , Magnetic Resonance Imaging/methods , Methacrylates/chemistry , Microscopy, Electron, Transmission , Nanoparticles/ultrastructure , Phosphorylcholine/chemical synthesis , Phosphorylcholine/chemistry , Polymethacrylic AcidsABSTRACT
The effect of varying both the solution pH and copolymer concentration on the structure of layers of poly[2-(methacryloyloxy)ethyl phosphorylcholine-block-2-(dimethylamino)ethyl methacrylate] copolymer (denoted as MPC(30)-DMA(60), M(n) = 18,000) adsorbed at the air/water interface is studied using surface tension and specular neutron reflection. The surface structure of the adsorbed diblock copolymer is represented by a dense layer of 10-15 A on the air side, accompanied by a loose layer of 20-30 A extending into the aqueous phase. Although the uniform layer model generally provided a reasonable description of the adsorbed copolymer chains, some deviations were observed. A more detailed analysis showed that the distribution of the copolymer across the interface required a minimum of three layers to take into account the structural inhomogeneities. Refinement of the structural distributions involved the combined fitting of partially deuterated copolymer in null reflecting water and D(2)O and the fully hydrogenated copolymer in D(2)O, leading to a substantial improvement in the reliability of the structural profiles obtained. The data analysis showed an increase in surface excess at higher copolymer concentrations and at more alkaline pH. However, the copolymer layer was fully immersed in water under all conditions studied. Because the surface excess showed a steady increase across the cmc over the high pH range, we speculate that copolymer adsorption above the cmc involves the formation of surface micellar aggregates under these conditions.
Subject(s)
Biocompatible Materials/chemistry , Membranes, Artificial , Methacrylates , Neutrons , Phase Transition , Phosphorylcholine , Adsorption , Deuterium Oxide/chemistry , Hydrogen-Ion Concentration , Surface TensionSubject(s)
Antineoplastic Agents, Phytogenic/administration & dosage , Camptothecin/analogs & derivatives , Chemoembolization, Therapeutic/methods , Drug Delivery Systems/methods , Animals , Antineoplastic Agents, Phytogenic/blood , Antineoplastic Agents, Phytogenic/chemistry , Antineoplastic Agents, Phytogenic/pharmacokinetics , Camptothecin/administration & dosage , Camptothecin/blood , Camptothecin/chemistry , Camptothecin/pharmacokinetics , Hepatic Artery , Infusions, Intra-Arterial , Irinotecan , Liver Neoplasms/drug therapy , Liver Neoplasms/metabolism , Liver Neoplasms/secondary , SwineABSTRACT
Poly[2-(dimethylamino)ethyl methacrylate-b-2-methacryloyloxyethyl phosphorylcholine] (DMA-MPC) is currently under investigation as a new vector candidate for gene therapy. The DMA block has been previously demonstrated to condense DNA effectively. The MPC block contains a phosphorylcholine (PC) headgroup, which can be found naturally in the outside of the cell membrane. This PC-based polymer is extremely hydrophilic and acts as a biocompatible steric stabilizer. In this study, we assess in detail the morphologies of DNA complexes obtained using the diblock copolymer series DMA(x)MPC30 (where the mean degree of polymerization of the MPC block was fixed at 30 and the DMA block length was systematically varied) using transmission electron microscopy (TEM) and liquid atomic force microscopy (AFM). Both techniques indicate more compact complex morphologies (more efficient condensation) as the length of the cationic DMA block increases. However, the detailed morphologies of the DMA(x)MPC30-DNA complexes observed by TEM in vacuo and by AFM in aqueous medium are different. This phenomena is believed to be related to the highly hydrophilic nature of the MPC block. TEM studies revealed that the morphology of the complexes changes from loosely condensed structures to highly condensed rods, toroids, and oval-shaped particles as the DMA moiety increases. In contrast, morphological changes from plectonemic loops to flower-like and rectangular block-like structures, with an increase in highly condensed central regions, are observed by in situ AFM studies. The relative population of each structure is clearly dependent on the polymer molecular composition. Enzymatic degradation assays revealed that only the DMA homopolymer provided effective DNA protection against DNase I degradation, while other highly condensed copolymer complexes, as judged from TEM and gel electrophoresis, only partially protected the DNA. However, AFM images indicated that the same highly condensed complexes have less condensed regions, which we believe to be the initiation sites for enzymatic attack. This indicates that the open structures observed by AFM of the DNA complexation by the DMA(x)MPC30 copolymer series are closer to in vivo morphology when compared to TEM.
Subject(s)
DNA/administration & dosage , Gene Transfer Techniques , Methacrylates/chemistry , Phosphorylcholine/analogs & derivatives , Phosphorylcholine/pharmacology , Biopolymers/chemistry , Biopolymers/pharmacology , Cations , Cell Membrane/metabolism , DNA/chemistry , DNA/metabolism , Deoxyribonuclease I/metabolism , Electrophoresis, Agar Gel , Genetic Therapy , Methacrylates/pharmacology , Microscopy, Atomic Force , Microscopy, Electron, Transmission , Nucleic Acid Conformation , Phosphorylcholine/chemistryABSTRACT
Two synthetic routes to folic acid (FA)-functionalized diblock copolymers based on 2-(methacryloyloxy)ethyl phosphorylcholine [MPC] and either 2-(dimethylamino)ethyl methacrylate [DMA] or 2-(diisopropylamino)ethyl methacrylate [DPA] were explored. The most successful route involved atom transfer radical polymerization (ATRP) of MPC followed by the tertiary amine methacrylate using a 9-fluorenylmethyl chloroformate (Fmoc)-protected ATRP initiator. Deprotection of the Fmoc groups produced terminal primary amine groups, which were conjugated with FA to produce two series of novel FA-functionalized biocompatible block copolymers. Nonfunctionalized MPC-DMA diblock copolymers have been previously shown to be effective synthetic vectors for DNA condensation; thus, these FA-functionalized MPC-DMA diblock copolymers appear to be well suited to gene therapy applications based on cell targeting strategies. In contrast, the FA-MPC-DPA copolymers are currently being evaluated as pH-responsive micellar vehicles for the delivery of highly hydrophobic anticancer drugs.