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Biomedical subjects

J Donnelly

Publications and source records attributed to J Donnelly.

At least 55 records · Page 3Linked to original sources
PubMed1998

Performance of N95 respirators: filtration efficiency for airborne microbial and inert particles.

In 1995 the National Institute for Occupational Safety and Health issued new regulations for nonpowered particulate respirators (42 CFR Part 84). A new filter certification system also was created. Among the new particulate respirators that have entered the market, the N95 respirator is the most commonly used in industrial and health care environments. The filtration efficiencies of unloaded N95 particulate respirators have been compared with those of dust/mist (DM) and dust/fume/mist (DFM) respirators certified under the former regulations (30 CFR Part 11). Through laboratory tests with NaCl certification aerosols and measurements with particle-size spectrometers, N95 respirators were found to have higher filtration efficiencies than DM and DFM respirators and noncertified surgical masks. N95 respirators made by different companies were found to have different filtration efficiencies for the most penetrating particle size (0.1 to 0.3 micron), but all were at least 95% efficient at that size for NaCl particles. Above the most penetrating particle size the filtration efficiency increases with size; it reaches approximately 99.5% or higher at about 0.75 micron. Tests with bacteria of size and shape similar to Mycobacterium tuberculosis also showed filtration efficiencies of 99.5% or higher. Experimental data were used to calculate the aerosol mass concentrations inside the respirator when worn in representative work environments. The penetrated mass fractions, in the absence of face leakage, ranged from 0.02% for large particle distributions to 1.8% for submicrometer-size welding fumes. Thus, N95 respirators provide excellent protection against airborne particles when there is a good face seal.

Aerosols↗
PubMed1997

Estimates of reports of notifiable diseases by general practitioners in regional Western Australia.

We surveyed the attitudes of general practitioners to the notification of gazetted diseases in the south-west of Western Australia. Notification rates were calculated from the number of notifications recorded by the Southern Public Health Unit or the Communicable Disease Control Program of the State Health Department, and the estimated population of the region, the metropolitan area and the State. Of the 80% of general practitioners responding to the survey, 96% advised they intended to notify all gazetted diseases they diagnosed. Notification rates in the south-west of Western Australia ranged from 380 to 900 per 100,000 population, compared with approximately 450 per 100,000 population in the metropolitan area.

Attitude of Health Personnel↗
PubMed1997

Immunization of non-human primates with DNA vaccines.

The pre-clinical efficacy of DNA vaccines has been demonstrated in a number of animal models, but more limited data exist regarding their immunogenicity in non-human primates. The studies described below demonstrate that DNA vaccines in reasonable dosages encoding a variety of viral proteins could result in the generation of antibodies, neutralizing antibodies, or cytotoxic T lymphocytes in primates. Furthermore, these responses could be boosted by repeat administration of the DNA vaccine. In an effort to assess the safety of such vaccines sera from primates was shown to lack anti-DNA antibodies.

Animals↗
PubMed1997

Performance of N95 respirators: reaerosolization of bacteria and solid particles.

If a respirator does not contain an exhalation value, and the respirator wearer sneezes or coughs, one may expect previously collected particles to be reaerosolized. This may be of special concern in environments contaminated with airborne microorganisms. The percentages of reaerosolization were measured in a test setup where the number of reaerosolized particles were registered by dynamic aerosol size spectrometry relative to the number of previously collected particles or bacteria. Experiments at low relative humidity have shown that the reaerosolization of particles below 1 micron, including Mycobacterium tuberculosis surrogate bacteria, does not exceed 0.025%, even if the re-entrainment air velocity is as high as 300 cm/sec (i.e., 37 times the air velocity through the respirator during breathing under heavy workload conditions). The reaerosolization of larger particles into dry air was significant at the highest re-entrainment velocity of 300 cm/sec, which simulates violent sneezing or coughing: 0.1% for 3 microns and about 6% for 5-micron test particles. No reaerosolization was detected at relative humidity levels exceeding 35% at these conditions. Thus, it is concluded that the reaerosolization of particles and bacteria, collected on the fibrous filters of N95 respirators, is insignificant at conditions encountered in respirator wear.

Aerosols↗
PubMed1997

An exploration of attitudes on sexuality at a northeastern urban university.

This study was conducted to assess the prevalence of scores on homophobia among 104 college students at a northeastern urban university. Participants reported their attitudes regarding homosexuals and homosexual behavior on Hudson and Rickett's Index of Homophobia. The 33 men indicated more negative attitudes about homosexuals and homosexual situations than the 71 women.

Adult↗
PubMed1996

Immunogenicity of heptavalent pneumococcal conjugate vaccine in infants.

OBJECTIVE: To evaluate the safety, immunogenicity, and immunologic memory in young infants of a seven-valent (6B, 14, 19F, 23F, 18C, 4, 9V) pneumococcal vaccine conjugated to the outer membrane protein complex of Neisseria meningitidis. VACCINEES: Healthy 2-month-old infants 12- to 15-month-old control infants were recruited from participating private practices. METHODS: Infants (n = 25) were vaccinated at 2, 4, and 6 months of age with the conjugated pneumococcal vaccine, followed by a single dose of licensed pneumococcal polysaccharide vaccine (n = 20) at 12 to 15 months of age. Thirteen infants who had not received the investigational pneumococcal conjugate vaccine served as control subjects and were given a single dose of the licensed pneumococcal polysaccharide vaccine at 12 to 15 months of age. RESULTS: The investigational pneumococcal conjugate vaccine was well tolerated by infants. The vaccine was highly immunogenic in young infants, with significant increases in antibody to all seven serotypes after either two or three injections. At 12 to 15 months of age, infants who had been primed with the investigational pneumococcal conjugate vaccine had a brisk immunologic response to the booster injection of the licensed pneumococcal polysaccharide vaccine. Control infants, who received a single primary injection of the licensed pneumococcal polysaccharide vaccine, had negligible immunologic responses to four of the seven serotypes and low responses to the other three types. CONCLUSION: The investigational seven-valent pneumococcal conjugate vaccine administered to young infants was well tolerated and highly immunogenic and provided immunologic memory to an injection of the licensed pneumococcal polysaccharide vaccine.

Bacterial Outer Membrane Proteins↗
PubMed1996

Penetration of airborne microorganisms through a surgical mask and a dust/mist respirator.

This study investigated bacterial penetration of different bacterial shapes, aerodynamic sizes, and flow rates through a surgical mask and a dust/mist respirator. The bacterial penetrations were compared with those of spherical corn oil particles of the same aerodynamic diameter tested under the same conditions. The tests were performed at different levels of aerosol penetration. Bacteria, ranging from spherical to rod-shaped with a high aspect (length to width) ratio, were selected as test agents. Among these, Pseudomonas fluorescens physically simulates Mycobacterium tuberculosis by shape and size. The concentrations of bacteria upstream and downstream of the test devices were measured with an aerodynamic size spectrometer. This instrument was found to measure the total viable and nonviable bacterial concentration effectively and dynamically over the entire bacterial size range down to 0.5 microns in aerodynamic size. The results indicate that the spherical corn oil particles and the spherical Streptococcus salivarius bacteria have the same penetration in the size range from 0.9 to 1.7 microns. It has been found that rod-shaped bacteria penetrate less. The penetration difference between the spherical and rod-shaped bacteria depends on the aspect ratio of the bacteria. For an aspect ratio of 4, the penetration of rod-shaped bacteria is about half that of spherical ones. Thus, it is projected that a respirator with 90% efficiency against spherical microorganisms or test particles (10% penetration) will be 95% efficient against rod-shaped microorganisms of the same aerodynamic equivalent diameter with an aspect ratio of 3 to 4, such as Mycobacterium tuberculosis (5% penetration).

Aerosols↗
PubMed1996

Comparison of methods for detection and enumeration of airborne microorganisms collected by liquid impingement.

Bacterial agents and cell components can be spread as bioaerosols, producing infections and asthmatic problems. This study compares four methods for the detection and enumeration of aerosolized bacteria collected in an AGI-30 impinger. Changes in the total and viable concentrations of Pseudomonas fluorescens in the collection fluid with respect to time of impingement were determined. Two direct microscopic methods (acridine orange and BacLight) and aerodynamic aerosol-size spectrometry (Aerosizer) were employed to measure the total bacterial cell concentrations in the impinger collection fluid and the air, respectively. These data were compared with plate counts on selective (MacConkey agar) and nonselective (Trypticase soy agar) media, and the percentages of culturable cells in the collection fluid and the bacterial injury response to the impingement process were determined'. The bacterial collection rate was found to be relatively unchanged during 60 min of impingement. The aerosol measurements indicated an increased amount of cell fragments upstream of the impinger due to continuous bacterial nebulization. Some of the bacterial clusters, present in the air upstream of the impinger, deagglomerated during impingement, thus increasing the total bacterial count by both direct microscopic methods. The BacLight staining technique was also used to determine the changes in viable bacterial concentration during the impingement process. The percentage of viable bacteria, determined as a ratio of BacLight live to total counts was only 20% after 60 min of sampling. High counts on Trypticase soy agar indicated that most of the injured cells could recover. On the other hand, the counts from the MacConkey agar were very low, indicating that most of the cells were structurally damaged in the impinger. The comparison of data on the percentage of injured bacteria obtained by the traditional plate count with the data on percentage of nonviable bacteria obtained by the BacLight method showed good agreement.

Acridine Orange↗
PubMed1996

Assessing variability of HIV transmission attitudes and behaviors at an urban northeastern university.

Teenagers in the United States are one of the populations whose HIV infection rates are increasing most rapidly. This study was designed to measure college students' knowledge of HIV transmission methods using Kittleson and Venglarcik's HIV Transmission Survey. Participants (N= 167) were divided into two groups, 99 students from a rural background and 68 students from an urban background. Students from an urban background were significantly more knowledgeable about documented HIV transmission modes than students from a rural background. Men were significantly less aware of documented HIV transmission modes than women. These results suggest that education about AIDS needs to be improved. The current educational procedures do not properly inform students in a fashion which exhibits the true risk of infection and those behaviors which increase risk. Fifteen years after the discovery of the HIV virus students are still largely unaware that they are at risk for contracting a fatal disease.

Adolescent↗
PubMed1995

Factors affecting microbiological colony count accuracy for bioaerosol sampling and analysis.

The effects of the following variables on the occurrence of colony masking (the indistinguishable merging or overlap of sufficiently close colonies) were evaluated experimentally using the bacterium Bacillus subtilis: spore density on a collection surface, concentration of nutrients in the culture medium, sample incubation time, and ability of an observation system to distinguish overlapped colonies. Increasing spore surface density and incubation time increased colony masking, whereas lowering nutrient concentration decreased colony diameter and, therefore, masking but also limited spore germination and growth. Overall, full-strength medium was best for accurate counting of early microcolonies examined with the aid of a microscope, whereas half- or quarter-strength medium was better for counting older readily observable macrocolonies. Masking bias was determined for varying spore surface densities and colony diameters and was applied to two widely used slit-to-agar bioaerosol impactors. Appropriate collection times have been determined for these samplers to minimize colony masking for expected bioaerosol concentrations. It was found, for example, that 6-min samples collected from an environment with an air concentration of 10(3) CFU m-3 would result in colony surface densities, for 3-mm colonies, of 1.5 and 3.9 microorganisms cm-2 for the two samplers with respective masking biases of < 10% and < 20%.

Aerosols↗