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Biomedical subjects

G H Ward

Publications and source records attributed to G H Ward.

17 recordsLinked to original sources
PubMed2001

A powder formulation of measles vaccine for aerosol delivery.

Both the mortality rate for measles and the risks associated with injection continue to be high in the developing world. In response to the need for safe, cost-effective vaccine delivery technologies, a powder formulation of measles vaccine has been developed to test the feasibility of administering measles vaccine as an aerosol. The first challenge in aerosol formulation development is to produce fine particles without damaging the activity of the virus or inducing physical changes. In this study, live attenuated measles vaccine is micronized by jet milling to generate particle sizes appropriate for pulmonary delivery (1-5 microm). Milling does not induce detectable physical changes and significant viral potency is maintained. Potency retention of milled vaccine ranges from 31 to 89%, demonstrating that the standard dose of vaccine can easily be achieved. Following size reduction, particles are blended with an inert carrier to improve handling and aerosol dispersion. The measles vaccine formulation is dispersable, as shown by laser light particle size analysis of vaccine aerosols. Thus, evaluation of both the potency retention and the aerosol characteristics of the current formulation clearly demonstrates the feasibility of delivering measles vaccine as a powder aerosol for immunization.

Aerosols↗
PubMed1995

Process-induced crystallinity changes in albuterol sulfate and its effect on powder physical stability.

Pharmaceutical powders are often milled to achieve the optimum particle size. These size reduction processes can introduce dislocations and/or defects onto particle surfaces affecting the overall crystallinity of the powder. If enough energy is imparted, amorphous regions on the particle surfaces may be produced. These amorphous regions have the propensity to absorb significant quantities of water. In this study the effect of sorbed water on the physical characteristics of albuterol sulfate is investigated. Physical properties of this compound are studied in both micronized and unmicronized states using scanning electron microscopy, differential scanning calorimetry, powder x-ray diffraction, solution microcalorimetry, laser diffraction particle size analysis and water vapor sorption analysis. Subtle differences in crystallinity induced by air jet micronization are detected by several analytical methods. Amorphous to crystalline conversions are observed, the kinetics of which are found to be both temperature and relative humidity dependent. These experiments show the dynamic nature of micronized albuterol sulfate and aid in the determination of the actual physical state of this pharmaceutical powder.

Albuterol↗
PubMed1991

Studies in phlebitis: detection and quantitation using a thermographic camera.

A new method for the detection of acute phlebitis in superficial veins is investigated. A thermographic camera is utilized for the quantitation of temperature changes in a rabbit ear model. A control group receiving no injection is compared against each of five treatment groups receiving these commercially available parenterals: amiodarone hydrochloride, phenytoin sodium, mechlorethamine hydrochloride, cephalothin sodium, and diazepam. The vehicles of the above-mentioned drugs as well as several commonly used organic cosolvents are also investigated. Local tissue responses to the parenteral challenges are measured and a good correlation between the visual and the thermographic data was seen.

Animals↗
PubMed1985

A uni-directional urethral force gauge.

Until now urethral transducers have had poor circumferential resolution and have been inadequate for assessing whether the forces closing the female urethra are equally distributed around its circumference or whether they are greater in some directions than others. This paper describes a urethral force gauge which is capable of measuring urethral occlusive forces in a uni-directional manner because it is sensitive to forces around only 20 degrees of the urethral circumference. The gauge comprises a sensor, utilising two semi-conductor strain gauges, mounted at the tip of a 14 F silicone rubber catheter. It has been used in the investigation of 232 female patients and has proved to be reliable and robust.

Biomechanical Phenomena↗
PubMed1985

The anisotropic nature of urethral occlusive forces.

A newly-developed unidirectional force gauge was used to demonstrate that the urethral occlusive forces are unequal around the circumference of the female urethra. In the proximal two-thirds of the urethra significantly greater forces are exerted in the anterior position compared with those exerted in the lateral and posterior positions. By contrast the occlusive forces in the distal third of the urethra are greater in the posterior and lateral positions than in the anterior position. These findings hold true for both women with normal and abnormal urinary control. Rotational variations have previously been reported but have been thought to be artefact due to catheter stiffness; this study shows that rotational variations are genuine and not due to artefact.

Female↗
PubMed1983

A device for monitoring position of unrestrained animals in a temperature gradient.

The design and use of an automated system which permits continuous monitoring of the position of an animal in a temperature gradient is demonstrated. Animal position in the gradient is detected with phototransistors. Through simple electronic switching, the information from the phototransistors is converted to an analog DC signal that is directly proportional to the position of the animal in the temperature gradient. The temperature gradient method permits continuous automated monitoring of thermoregulatory behavior in unrestrained animals.

Animals↗
PubMed1974

Application and evaluation of portable field instruments for measuring forced expiratory volume of children and adults in environmental health surveys.

In support of Health Effects Research Studies, pulmonary function tests are periodically administered to a large number of children. The ventilatory performance of these children is being evaluated by measuring the 0.75-sec forced expiratory volume (FEV(0.75)) with a waterless mechanical volume spirometer used in conjunction with an electronic timing unit. During a 1-yr testing period, operation with the volume spirometer and the EPA designed electronic timing unit proved to be highly successful. The volume spirometer was found to be more advantageous in conducting tests at remote field stations than the water spirometer and other electronic instruments which measure flow rate with a transducer element. The volume spirometer is lightweight, easy to operate, and has the capability of easy and accurate field calibration when used in conjunction with the electronic timing unit. Presently the volume spirometer and EPA designed electronic timing package are employed in all Community Health and Surveillance System (CHESS) pulmonary function testing studies.

Adult↗
PubMedDate not supplied

The role of the effective concentration in interpreting hemolysis data.

Problems inherent in traditional methods of determining the hemolytic activity of parenteral compounds are discussed. Data taken from a study which closely models the conditions present for an intravenous injection are re-examined. An equation is given which combines several variables into a single parameter, the effective concentration. A strong relationship is found between the effective concentration of the compound of interest and the hemolysis produced.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

Studies in phlebitis. IV: Injection rate and amiodarone-induced phlebitis.

Using a rabbit ear model and techniques developed previously (1) the relationship between injection rate and injection phlebitis is investigated for amiodarone HCl and its vehicle. A number of injection rates ranging from 0.02 to 3.0 ml/min are studied using this model. Thermal measurements and visual evaluations are used for phlebitis quantitation. The severity of phlebitis is found to be dependent upon the injection rate for amiodarone HCl while the vehicle did not produce phlebitis at any rate. Strong correlations between the thermal measurements and visual evaluations are found for both amiodarone HCl and its vehicle.

Amiodarone↗