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Biomedical subjects

P Foreman

Publications and source records attributed to P Foreman.

At least 19 recordsLinked to original sources
PubMed2006

Influence of deposition and spray pattern of nasal powders on insulin bioavailability.

The influence of the deposition pattern and spray characteristics of nasal powder formulations on the insulin bioavailability was investigated in rabbits. The formulations were prepared by freeze drying a dispersion containing a physical mixture of drum dried waxy maize starch (DDWM)/Carbopol 974P (90/10, w/w) or a spray-dried mixture of Amioca starch/Carbopol 974P (25/75, w/w). The deposition in the nasal cavity of rabbits and in a silicone human nose model after actuation of three nasal delivery devices (Monopowder, Pfeiffer and experimental system) was compared and related to the insulin bioavailability. Posterior deposition of the powder formulation in the nasal cavity lowered the insulin bioavailability. To study the spray pattern, the shape and cross-section of the emitted powder cloud were analysed. It was concluded that the powder bulk density of the formulation influenced the spray pattern. Consequently, powders of different bulk density were prepared by changing the solid fraction of the freeze dried dispersion and by changing the freezing rate during freeze drying. After nasal delivery of these powder formulations no influence of the powder bulk density and of the spray pattern on the insulin bioavailability was observed.

Administration, Intranasal↗
PubMed2005

Characterization and in vivo evaluation of ocular minitablets prepared with different bioadhesive Carbopol-starch components.

The purpose of this study was to evaluate different bioadhesive ocular formulations based on drum dried waxy maize starch (DDWM), Amioca starch and Carbopol 974P. The concentrations of Carbopol 974P in the mixtures varied between 5 and 25% (w/w). The rheological properties of the non-sterilized and gamma-irradiated physical blends of Carbopol 974P with either DDWM or Amioca were compared to those of the corresponding co-spray dried Amioca starch/Carbopol powders. Higher viscosity or consistency values were measured for sterilized co-spray dried powder mixtures containing an amount of Carbopol 974P equal or above 15% (w/w) compared to the physical blends. Sustained release minitablets (2 mm, 6 mg), consisting of sodium fluorescein as model drug and the bioadhesive powders, were manufactured at a compression force of 1.25 kN. Afterwards, the tablets were sterilized with gamma-irradiation. The amount of Carbopol in the co-spray dried powder mixtures on the one hand and gamma-irradiation on the other hand had no significant influence on the crushing strength and friability of the minitablets evaluated. However, these two factors affected the in vitro release properties of the minitablets. The slowest release was obtained with tablets containing 25% Carbopol 974P, which unfortunately possess mucosal irritating properties. By using co-spray dried Amioca with 15% (w/w) Carbopol 974P, a slower release can be achieved compared to the physical mixtures of DDWM or Amioca starch with Carbopol 974P. Moreover, this ocular formulation is very promising and is preferred, as it did not cause any mucosal irritation and released the model drug for at least 12 h, after application in the fornix.

Acrylic Resins↗
PubMed2005

Spray-dried Amioca starch/Carbopol 974P mixtures as buccal bioadhesive carriers.

In the present study, spray-dried Amioca starch/Carbopol 974P mixtures were evaluated as potential buccal bioadhesive tablets. Carbopol (C 974P) concentrations from 5 to 75% were tested. All spray-dried mixtures showed a comparable or better bioadhesive capacity compared to a reference formulation (DDWM/C 974P 95/5). The bioadhesive capacities of Amioca/Carbopol 974P mixtures were improved by spray-drying. All spray-dried mixtures showed significantly higher work of adhesion values compared to their equivalent physical mixtures. The influence of Carbopol concentration on the in vivo adhesion time of placebo tablets and in vitro miconazole nitrate release was tested. The ratio Amioca/C 974P 70/30 showed the longest in vivo adhesion time (24.5+/-8.5 h). Lower and higher C 974P concentrations had a shorter in vivo adhesion time. The mixtures containing between 15 and 30% C 974P could all sustain the in vitro miconazole nitrate release over 20 h. Again, lower and higher C 974P concentrations showed a faster in vitro miconazole release. The drug loading capacity of a spray-dried mixture containing 20% C 974P was investigated in vivo in dogs using testosterone as model drug. The spray-dried mixture could be loaded with 60% drug without loosing its in vivo bioadhesive and pharmacokinetic properties.

Acrylates↗
PubMed2005

Starch/Carbopol spray-dried mixtures as excipients for oral sustained drug delivery.

The present study evaluated if mixtures prepared by spray-drying an aqueous dispersion of Amioca starch and Carbopol 974P could be used as matrix for oral sustained drug delivery. The influence of the Amioca/Carbopol 974P ratio (0/100, 25/75, 50/50, 60/40, 85/15, 90/10, 95/5 and 100/0) and the pH and ionic strength (mu) of the dissolution medium on the drug release was investigated. The matrices composed of the spray-dried mixtures with 10% or 15% Carbopol 974P sustained the drug release over the longest time period. At this Carbopol concentration, shear viscosity measurements indicated the formation of an optimal network between the polymer chains of Amioca starch and Carbopol 974P, forming a rigid gel layer offering resistance to erosion during the dissolution experiments.

Acrylic Resins↗
PubMed2004

Characterization of the protein processing and secretion pathways in a comprehensive set of expressed sequence tags from Trichoderma reesei.

Trichoderma reesei is a filamentous fungus widely used as an efficient protein producer and known to secrete large quantities of biomass degrading enzymes. Much work has been done aimed at improving the secretion efficiency of this fungus. It is generally accepted that the major bottlenecks in secretion are protein folding and ornamentation steps in this pathway. In an attempt to identify genes involved in these steps, the 5' ends of 21888 cDNA clones were sequenced from which a unique set of over 5000 were also 3' sequenced. Using annotation tools Gene Ontology terms were assigned to 2732 of the sequences. Homologs to the majority of Aspergillus niger's Srg genes as well as a number of homologs to genes involved in protein folding and ornamentation pathways were identified.

Computational Biology↗
PubMed2003

Evaluation of the mucosal irritation potency of co-spray dried Amioca/poly(acrylic acid) and Amioca/Carbopol 974P mixtures.

The purpose of this study was to evaluate the biocompatibility of different Amioca/poly(acrylic acid) and Amioca/Carbopol 974P co-spray dried mixtures with an alternative mucosal irritation test using slugs. The irritation potential of the mixtures was measured by the amount of mucus produced during a repeated 30-min contact period. Additionally, membrane damage was assessed by measuring the protein and enzyme release from the body wall of slugs after treatment. All the Amioca/poly(acrylic acid) co-spray dried mixtures (50:50 and 25:75 ratios) induced slight irritation of the mucosal tissue as was demonstrated by the significantly increased mucus production however no increased protein and enzyme release was detected. Co-spray dried Amioca/Carbopol 974P mixtures containing 40% and more Carbopol 974P demonstrated a significantly higher mucus production and release of cytosolic LDH, indicating membrane damage. The total mucus production of the slugs treated with the co-spray dried mixtures containing up to 20% Carbopol 974P was significantly higher compared to the blank slugs. However, these mixtures induced no membrane damage since no additional effect on the protein release and no enzyme release was detected. By co-spray drying up to 20% Carbopol 974P could be incorporated without showing a distinct sign of irritation. These mixtures can be considered as potentially safe bioadhesive carriers.

Acrylates↗
PubMed2003

Rheological study on mucoadhesivity of some nasal powder formulations.

Various powder mixtures were used to administer insulin via the nasal route: a co-spray dried mixture of Amioca starch and Carbopol 974 P (1/3), drum dried waxy maize starch and Carbopol 974 P (9/1), maltodextrin DE38/Carbopol 974 P (9/1) and pure drum dried waxy maize starch. Oscillatory rheology is performed to study and compare the viscosity, elasticity and mucoadhesivity of these powder formulations. There was no rheological synergism detectable with the co-spray dried mixture of Amioca starch and Carbopol 974 P (1/3), drum dried waxy maize starch and Carbopol 974 P (9/1) and maltodextrin DE38/Carbopol 974 P (9/1). Interaction due to entanglements was seen with drum dried waxy maize starch (100%). The differences in nasal bioavailability between the different carriers could be explained by differences in G' (storage modulus, elasticity) and G" (loss modulus, viscosity) values. The formulation giving the highest bioavailability, provided also the highest G' and G" values.

Adhesives↗
PubMed2002

Ex vivo bioadhesion and in vivo testosterone bioavailability study of different bioadhesive formulations based on starch-g-poly(acrylic acid) copolymers and starch/poly(acrylic acid) mixtures.

Starch-g-poly(acrylic acid) copolymers or grafted starches synthesized by 60Co irradiation or chemical modification and co-freeze-dried starch/poly(acrylic acid) mixtures were evaluated on their ex vivo bioadhesion capacity. The buccal absorption of testosterone from a bioadhesive tablet formulated with the grafted starches or starch/poly(acrylic acid) mixtures was investigated. The results were compared to a reference formulation (physical mixture of 5% Carbopol 974P and 95% Drum Dried Waxy Maize). Rice starch-based irradiated grafted starches showed the best bioadhesion results. Partial neutralization of the acrylic acid with Ca(2+) ions resulted in significantly higher bioadhesion values compared to the reference. Ca(2+) and Mg(2+) partially neutralized maltodextrin-based irradiated grafted starches showed significantly higher bioadhesion values compared to the reference formulation. The chemically modified grafted starches showed significantly higher adhesion force values than for the reference tablet. None of the co-freeze-dried starch/poly(acrylic acid) mixtures showed significantly higher bioadhesion results than the reference (Bonferroni test, P<0.05). A chemically modified grafted starch could sustain the 3 ng/ml plasma testosterone target concentration during +/- 8 h (T(>3 ng/ml)). By lyophilization of a partially neutralized irradiated grafted starch, the in vivo adhesion time (22.0 +/- 7.2 h) and the T(>3 ng/ml) (13.5 +/- 1.3 h) could be increased. The absolute bioavailability of the lyophilized formulation approached the reference formulation. Some of the grafted starches showed to be promising buccal bioadhesive drug carriers for systemic delivery.

Adhesives↗
PubMed2001

Trypsin inhibition, calcium and zinc ion binding of starch-g-poly(acrylic acid) copolymers and starch/poly(acrylic acid) mixtures for peroral peptide drug delivery.

Newly synthesised starch-g-poly(acrylic acid) copolymers and starch/poly(acrylic acid) mixtures were evaluated for their in vitro inhibition potency towards the proteolytic enzyme trypsin. Their Ca2+ and Zn2+ binding capacity was measured. Carbopol 934P was used as reference polymer. Starch-g-poly(acrylic acid) copolymers were prepared by chemical grafting and 60Co irradiation, the starch/poly(acrylic acid) mixtures by freeze-drying. The influence of preparation method, the ratio starch:acrylic acid, the neutralisation degree and for the freeze-dried polymers the influence of heat treatment after freeze-drying was investigated. All freeze-dried polymers showed a higher inhibition factor (IF) than the chemically grafted and 60Co irradiated starches, which all showed significantly lower IF than Carbopol 934P. The heat treated freeze-dried polymer Amioca/poly(acrylic acid) (1:1) showed a significantly higher IF than the reference polymer (Mann-Whitney test, p<0.05). The Ca2+ and Zn2+ binding capacity of all chemically grafted starches was much lower than for Carbopol 934P. Only the 60Co irradiated starches and freeze-dried polymers with ratio 1:3 approached the binding capacity of the reference polymer. The freeze-dried polymers showed the highest proteolytic enzyme inhibition potency. Freeze-drying and 60Co irradiation could result in the highest ion binding capacity. This combination of proteolytic enzyme inhibition activity and ion binding capacity makes these polymers hopeful excipients for successful oral peptide delivery.

Acrylic Resins↗
PubMed1998

Using augmentative communication with infants and young children with Down syndrome.

This paper reports the use of two forms of augmentative and alternative communication (AAC) with young children with Down syndrome: a program using signing (Makaton), and the COMPIC system of computerised pictographs. Children with Down syndrome are frequently reported to have difficulties in the area of language and communication, with relative strengths in visual and perceptual areas. This suggests possible benefits from the use of AAC systems to enhance language development. The paper discusses the use of AAC systems to assist young children with Down syndrome, and reports an experimental study of the use of such systems with an object naming task.

Child, Preschool↗
PubMed1997

Labour force participation and employment among a sample of Australian patients with a spinal cord injury.

This study examined the employment achievements of 219 spinal cord injured people and attempted to identify predictors which, individually and in combination, (a) discriminated between those who were in the labour force or not, and (b) correlated with the amount of time in employment post injury. Results indicated that at the time of the survey 26% were in full-time work, 11% were in part-time work, 4% were unemployed and 59% were not actively seeking work. Multivariate analyses identified three variables (impairment type, study since injury, level of pre-injury secondary schooling) which were related to both labour force participation and the amount of work undertaken post-injury. These results are discussed with reference to post-injury services that could be offered to spinal cord injury people who wish to return to work or gain employment.

Adolescent↗
PubMed1996

Association of prelesion sports participation and involvement in wheelchair sports following spinal cord injury.

116 individuals with spinal cord injury were surveyed to investigate the relationship between prelesion sports participation and involvement in wheelchair sports following injury. While 89 reported they had been involved in sport prior to their injury, only 38 (43%) of these were involved since injury. 27 respondents said that they had not participated in sport preinjury; however, 13 (48%) of these reported that they had become involved since injury. Analysis by chi 2 showed that, for this sample at least, the tendency for an individual with spinal cord injury to be involved in wheelchair sports was not related to preinjury history of sports involvement.

Adolescent↗
PubMed1986

The kinetics of clearance of human antibody/dsDNA immune complexes from rabbit circulation. Effects of dsDNA size, rheumatoid factor, and reduction and alkylation of the antibodies.

We have conducted in vivo investigations of the rate of clearance of prepared antibody/dsDNA immune complexes from the circulation of rabbits and have correlated the results with some in vitro immunologic properties of the complexes. Those complexes that fix complement most efficiently in vitro (as manifested by their complement-mediated binding to human red blood cells or rabbit platelets) are cleared most rapidly. Factors that decrease this binding such as reduction and alkylation of the antibodies or the use of dsDNA of a lower m.w. also tend to prolong the circulation times for the complexes. This study provides additional evidence in support of a complement-mediated platelet immune complex clearance mechanism in non-primates that parallels the erythrocyte immune complex clearance mechanism in primates first described by He bert. Finally, the implications of our findings with respect to the importance of dsDNA size in the pathogenesis of systemic lupus erythematosus are discussed.

Alkylation↗