Niall Behan - Academia.edu (original) (raw)

Papers by Niall Behan

Research paper thumbnail of In vitro comparison of a novel nebulizer with ultrasonic and pneumatic nebulizers

Journal of Allergy and Clinical Immunology, 2003

GlaxoSmithKline, Research Triangle Park, NC. RATIONALE: Compare asthma exacerbations rates and qu... more GlaxoSmithKline, Research Triangle Park, NC. RATIONALE: Compare asthma exacerbations rates and quantify direct medical costs during treatment with fluticasone propionate/salmeterol combination product (FSC; 100/50 BID) vs fluticasone propionate (FP; 88 mcg BID) or montelukast (MEN; 10 mg QD). METHODS: Data from four double-blind, double-dummy, randomized controlled trials that compared FSC with MeN ( 12-weeks trials) or MeN with FP (24-weeks trials) in patients previously uncontrolled on albuterol alone. The 12-week data from all studies was analyzed, A Cox proportional hazard analysis was performed on time to asthma exacerbation while direct costs were determined by applying standard costs to physician office visits; asthma related emergency department visits and hospitalizations that occurred during the exacerbations. RESULTS: The analysis included 1910 patients _>15 years symptomatic on albuterol alone. Baseline characteristics were similar between groups. Compared with FSC, FP patients had a 2.6 (95% CI 1.04, 6.49) times greater risk of having an asthma related exacerbation while MeN patients had a 3.6 (95% CI 1.52, 8.31 ) times greater risk of having an asthma related exacerbation within 12 weeks of starting therapy. Exacerbation cost per RATIONALE: Nebulizers vary in the amount of inhaled mass delivered and the time required to administer treatment. METHODS: We compared the performance of ultrasonic and pneumatic nebulizers with a prototype nebulizer (Aerogen). Albuterol sulfate (3 mL) was administered to a breath simulator (Vt 500 mL, rate 15, and 0.35 duty cycle) with each device (n=3). Drug deposited on an absolute filter (Inhaled Mass) was assayed (HPLC). Flow rate (mL/min) of emitted aerosol, and residual volume (mL) remaining in the nebulizer were determined gravimetrically. Treatment time to end of dose or sputter was recorded. Volume Median Diameter (VMD) was determined by laser diffraction (SpraytecbTm).

Research paper thumbnail of S1110 A New Removable Endoluminal Prosthesis for Control of Gastroesophageal Reflux (GER

Research paper thumbnail of Synthesis and In-vitro drug release of insulin-loaded poly(n-butyl cyanoacrylate) nanoparticles

Macromolecular Bioscience, 2002

Nanoparticles have been prepared by dispersion polymerisation of n-butyl cyanoacrylate in acidifi... more Nanoparticles have been prepared by dispersion polymerisation of n-butyl cyanoacrylate in acidified water, with and without the inclusion of insulin. The molecular weight of the polymerising material increases by a stepwise process, in which chains are initiated, terminated, and reinitiated, ...

Research paper thumbnail of The mechanism of polymerisation of butyl cyanoacrylate in aqueous dispersions

Macromolecular Rapid Communications, 2000

ABSTRACT

Research paper thumbnail of The mechanism of polymerisation of butyl cyanoacrylate in aqueous dispersions

Macromolecular Rapid Communications, 2000

ABSTRACT

Research paper thumbnail of Preparation of Poly(butyl cyanoacrylate) Nanoparticles by Aqueous Dispersion Polymerisation in the Presence of Insulin

Macromolecular Rapid Communications, 2001

ABSTRACT

Research paper thumbnail of Poly n-butyl cyanoacrylate nanoparticles: a mechanistic study of polymerisation and particle formation

Biomaterials, 2001

Poly n-butyl cyanoacrylate has been used in the synthesis of nanoparticles by dispersion polymeri... more Poly n-butyl cyanoacrylate has been used in the synthesis of nanoparticles by dispersion polymerisation in aqueous media. Following establishment of a thermometric procedure for assessment of monomer reactivity, the relationships between mono-mer}polymer conversion reactions and particle development at various pH values was investigated. Particle size was measured during the synthesis process using a laser di!raction technique and "nal particle character was assessed by scanning electron microscopy. Optimum conditions for particle production were a dispersion medium of pH 2.5 at a temperature of 653C, with dextran 70 used as a steric stabiliser. In the presence of dextran, following a period of equilibration, colloidally stable particles form, but in the absence of dextran particles are colloidally unstable and rapidly coalesce. Measurement of molecular weight changes through the synthesis process show an upward shift consistent with the initial formation of oligomers, which then further polymerise through a re-initiation re-polymerisation process until an equilibrium molecular weight is reached.

Research paper thumbnail of Preparation of Poly(butyl cyanoacrylate) Nanoparticles by Aqueous Dispersion Polymerisation in the Presence of Insulin

Macromolecular Rapid Communications, 2001

ABSTRACT

Research paper thumbnail of Factors Controlling Particle Size during Nebulization of DNA?Polycation Complexes

Journal of Aerosol Medicine-deposition Clearance and Effects in The Lung, 2007

Pulmonary gene therapy has the potential to treat or cure respiratory diseases such as cystic fib... more Pulmonary gene therapy has the potential to treat or cure respiratory diseases such as cystic fibrosis. Much work has focused on the delivery of genes to the lung using viral vectors with varying degrees of success. Viral vectors are problematic and undesirable for use in the lung because they can provoke an acute immune response. This study has focused on the characterization of nonviral, polymer-based gene vectors for use with nebulizers. Calf thymus DNA has been used as a model, and was complexed with each of the three polycations; 22 kDa linear polyethyleneimine, 25 kDa branched polyethyleneimine, and 29.5 kDa polylysine using water, glucose solution, and phosphate-buffered saline (PBS) as carrier liquids. Fourier transform infrared spectroscopy has shown that the DNA retains the B form during the complex formation. The complexes prepared at N:P ratios of 10, have been nebulized using a vibrating plate nebulizer and the particle size and Zeta potentials measured before and after nebulization. The particle size distributions of the DNA complexes prepared in water and glucose solution were unimodal before and after nebulization with a small increase in particle size following nebulization. Choice of complexing polymer is shown to have only a small effect on particle size with the dominant effect coming from the ionic character of the dispersion fluid. Complexes prepared in PBS, although originally unimodal, showed pronounced agglomeration on nebulization. With all polymers in water or glucose solution, the Zeta potential increases after nebulization, but with PBS as the carrier liquid the potential falls and is clearly associated with the observed agglomeration. Gel electrophoresis shows that the complexing polymers protect the DNA through the nebulization process in all cases.

Research paper thumbnail of In vitro comparison of a novel nebulizer with ultrasonic and pneumatic nebulizers

Journal of Allergy and Clinical Immunology, 2003

GlaxoSmithKline, Research Triangle Park, NC. RATIONALE: Compare asthma exacerbations rates and qu... more GlaxoSmithKline, Research Triangle Park, NC. RATIONALE: Compare asthma exacerbations rates and quantify direct medical costs during treatment with fluticasone propionate/salmeterol combination product (FSC; 100/50 BID) vs fluticasone propionate (FP; 88 mcg BID) or montelukast (MEN; 10 mg QD). METHODS: Data from four double-blind, double-dummy, randomized controlled trials that compared FSC with MeN ( 12-weeks trials) or MeN with FP (24-weeks trials) in patients previously uncontrolled on albuterol alone. The 12-week data from all studies was analyzed, A Cox proportional hazard analysis was performed on time to asthma exacerbation while direct costs were determined by applying standard costs to physician office visits; asthma related emergency department visits and hospitalizations that occurred during the exacerbations. RESULTS: The analysis included 1910 patients _>15 years symptomatic on albuterol alone. Baseline characteristics were similar between groups. Compared with FSC, FP patients had a 2.6 (95% CI 1.04, 6.49) times greater risk of having an asthma related exacerbation while MeN patients had a 3.6 (95% CI 1.52, 8.31 ) times greater risk of having an asthma related exacerbation within 12 weeks of starting therapy. Exacerbation cost per RATIONALE: Nebulizers vary in the amount of inhaled mass delivered and the time required to administer treatment. METHODS: We compared the performance of ultrasonic and pneumatic nebulizers with a prototype nebulizer (Aerogen). Albuterol sulfate (3 mL) was administered to a breath simulator (Vt 500 mL, rate 15, and 0.35 duty cycle) with each device (n=3). Drug deposited on an absolute filter (Inhaled Mass) was assayed (HPLC). Flow rate (mL/min) of emitted aerosol, and residual volume (mL) remaining in the nebulizer were determined gravimetrically. Treatment time to end of dose or sputter was recorded. Volume Median Diameter (VMD) was determined by laser diffraction (SpraytecbTm).

Research paper thumbnail of S1110 A New Removable Endoluminal Prosthesis for Control of Gastroesophageal Reflux (GER

Research paper thumbnail of Synthesis and In-vitro drug release of insulin-loaded poly(n-butyl cyanoacrylate) nanoparticles

Macromolecular Bioscience, 2002

Nanoparticles have been prepared by dispersion polymerisation of n-butyl cyanoacrylate in acidifi... more Nanoparticles have been prepared by dispersion polymerisation of n-butyl cyanoacrylate in acidified water, with and without the inclusion of insulin. The molecular weight of the polymerising material increases by a stepwise process, in which chains are initiated, terminated, and reinitiated, ...

Research paper thumbnail of The mechanism of polymerisation of butyl cyanoacrylate in aqueous dispersions

Macromolecular Rapid Communications, 2000

ABSTRACT

Research paper thumbnail of The mechanism of polymerisation of butyl cyanoacrylate in aqueous dispersions

Macromolecular Rapid Communications, 2000

ABSTRACT

Research paper thumbnail of Preparation of Poly(butyl cyanoacrylate) Nanoparticles by Aqueous Dispersion Polymerisation in the Presence of Insulin

Macromolecular Rapid Communications, 2001

ABSTRACT

Research paper thumbnail of Poly n-butyl cyanoacrylate nanoparticles: a mechanistic study of polymerisation and particle formation

Biomaterials, 2001

Poly n-butyl cyanoacrylate has been used in the synthesis of nanoparticles by dispersion polymeri... more Poly n-butyl cyanoacrylate has been used in the synthesis of nanoparticles by dispersion polymerisation in aqueous media. Following establishment of a thermometric procedure for assessment of monomer reactivity, the relationships between mono-mer}polymer conversion reactions and particle development at various pH values was investigated. Particle size was measured during the synthesis process using a laser di!raction technique and "nal particle character was assessed by scanning electron microscopy. Optimum conditions for particle production were a dispersion medium of pH 2.5 at a temperature of 653C, with dextran 70 used as a steric stabiliser. In the presence of dextran, following a period of equilibration, colloidally stable particles form, but in the absence of dextran particles are colloidally unstable and rapidly coalesce. Measurement of molecular weight changes through the synthesis process show an upward shift consistent with the initial formation of oligomers, which then further polymerise through a re-initiation re-polymerisation process until an equilibrium molecular weight is reached.

Research paper thumbnail of Preparation of Poly(butyl cyanoacrylate) Nanoparticles by Aqueous Dispersion Polymerisation in the Presence of Insulin

Macromolecular Rapid Communications, 2001

ABSTRACT

Research paper thumbnail of Factors Controlling Particle Size during Nebulization of DNA?Polycation Complexes

Journal of Aerosol Medicine-deposition Clearance and Effects in The Lung, 2007

Pulmonary gene therapy has the potential to treat or cure respiratory diseases such as cystic fib... more Pulmonary gene therapy has the potential to treat or cure respiratory diseases such as cystic fibrosis. Much work has focused on the delivery of genes to the lung using viral vectors with varying degrees of success. Viral vectors are problematic and undesirable for use in the lung because they can provoke an acute immune response. This study has focused on the characterization of nonviral, polymer-based gene vectors for use with nebulizers. Calf thymus DNA has been used as a model, and was complexed with each of the three polycations; 22 kDa linear polyethyleneimine, 25 kDa branched polyethyleneimine, and 29.5 kDa polylysine using water, glucose solution, and phosphate-buffered saline (PBS) as carrier liquids. Fourier transform infrared spectroscopy has shown that the DNA retains the B form during the complex formation. The complexes prepared at N:P ratios of 10, have been nebulized using a vibrating plate nebulizer and the particle size and Zeta potentials measured before and after nebulization. The particle size distributions of the DNA complexes prepared in water and glucose solution were unimodal before and after nebulization with a small increase in particle size following nebulization. Choice of complexing polymer is shown to have only a small effect on particle size with the dominant effect coming from the ionic character of the dispersion fluid. Complexes prepared in PBS, although originally unimodal, showed pronounced agglomeration on nebulization. With all polymers in water or glucose solution, the Zeta potential increases after nebulization, but with PBS as the carrier liquid the potential falls and is clearly associated with the observed agglomeration. Gel electrophoresis shows that the complexing polymers protect the DNA through the nebulization process in all cases.