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Biomedical subjects

L A Taylor

Publications and source records attributed to L A Taylor.

71 records · Page 4Linked to original sources
PubMed1969

Paraformaldehyde for surface sterilization and detoxification.

Paraformaldehyde powder, depolymerized by heat, produced formaldehyde gas that was effective in sterilizing laboratory rooms, a mobile laboratory trailer, various surfaces, fiberglass filter medium, and specialized laboratory equipment. A sporulating and nonsporulating strain of bacteria, a virus, and a bacterial toxin were used as test agents. The dissemination procedures and equipment, the assay techniques, and the facilities and equipment sterilized were described.

Bacillus subtilis↗
PubMed1968

Microbiological evaluation of a large-volume air incinerator.

Two semiportable metal air incinerators, each with a capacity of 1,000 to 2,200 standard ft(3) of air per min, were constructed to sterilize infectious aerosols created for investigative work in a microbiological laboratory. Each unit has about the same air-handling capacity as a conventional air incinerator with a brick stack but costs only about one-third as much. The units are unique in that the burner housing and combustion chamber are air-tight and utilize a portion of the contaminated air stream to support combustion of fuel oil. Operation is continuous. Aerosols of liquid and dry suspensions of Bacillus subtilis var. niger spores and dry vegetative cells of Serratia marcescens were disseminated into the two incinerators to determine the conditions required for sterilization of contaminated air. With the latter organisms (concentration 2.03 x 10(7) cells/ft(3) of air), a temperature of 525 F (274 C), measured at the firebox in front of the heat exchanger, was sufficient for sterilization. To sterilize 1.74 x 10(7) and 1.74 x 10(9) wet spores of B. subtilis per ft(3), the required temperature ranged from 525 to 675 F (274 to 357 C) and 625 to 700 F (329 to 371 C), respectively. Air-sterilization temperature varied with each incinerator. This was because of innate differences of fabrication, different spore concentrations, and use of one or two burners With dry B. subtilis spores (1.86 x 10(8)/ft(3)), a temperature of 700 F was required for sterilization. With dry spores, no difference was noted in the sterilization temperature for the two incinerators.

Air Microbiology↗
PubMed1968

Containment of microbial aerosols in a microbiological safety cabinet.

A microbiological safety cabinet was evaluated to determine conditions under which microorganisms might escape. Tests were conducted under three cabinet-closure conditions, various airflow velocities, and different laboratory operations, with 10(5), 1.1 x 10(5), and 10(6) microorganisms per cubic foot of cabinet space released per min for 5 min. The data revealed that (i) escape of a human infectious dose is possible when the cabinet is used with the glove panel off; (ii) the number of organisms that escaped from the cabinet increased with a decrease in air velocity; and (iii) an increase in the number of laboratory operations resulted in an increase in the number of organisms that escaped. Thus, when the glove panel was off, the cabinet was only safe for operations that released a small number of microorganisms into the cabinet, whereas the cabinet was safe for operations of significantly greater hazard when used with the glove panel on but with the gloves unattached.

Aerosols↗
PubMed1967

Microbiological laboratory hazard of bearded men.

An investigation was conducted to evaluate the hypothesis that a bearded man subjects his family and friends to risk of infection if his beard is contaminated by infectious microorganisms while he is working in a microbiological laboratory. Bearded and unbearded men were tested with Serratia marcescens and Bacillus subtilis var. niger. Contact aerosol transmission from a contaminated beard on a mannequin to a suitable host was evaluated with both Newcastle disease virus and Clostridium botulinum toxin, type A. The experiments showed that beards retained microorganisms and toxin despite washing with soap and water. Although washing reduced the amount of virus or toxin, a sufficient amount remained to produce disease upon contact with a suitable host.

Aerosols↗
PubMedDate not supplied

Immunofluorescent determination of the lobular distribution of a constitutive form of hepatic microsomal cytochrome P-450.

We have used an immunohistochemical approach to study the lobular distribution of constitutive liver microsomal cytochrome P-450. Cytochrome P-450 isolated (10.3 nmoles per mg protein) from hepatic microsomes from untreated, mature male Sprague-Dawley rats was used to produce antisera in rabbits. The IgG fraction produced single precipitin lines of identity with liver microsomes after double immunodiffusion, precipitated 80% of the total microsomal cytochrome P-450 and inhibited three cytochrome P-450-dependent enzyme activities. By these criteria, the IgG appeared to be specific for a constitutive form (or immunochemically related family) of liver microsomal cytochrome P-450. The pattern of fluorescence after indirect immunofluorescent labeling of liver sections depended on the route of tissue preparation and the concentration of primary antibody. In frozen sections, the labeling was uniform throughout the lobule, whereas in "antigen-depleted" paraffin-embedded sections it was heaviest in the centrilobular and midzonal regions. Increasing the concentration of primary antibody to 500 micrograms per ml inhibited the centrilobular labeling in frozen sections in a concentration-dependent manner. When specific isozymes of cytochrome P-450 were induced with phenobarbital or 3-methylcholanthrene, the constitutive cytochrome P-450 was localized predominantly in the periportal region. Decreases in cytochrome P-450 in rats treated with carbon tetrachloride or 1,2-dibromo-3-chloropropane were associated with antigen loss only in necrotic cells. Regional differences in the loss of antigen in paraffin sections and the inhibition of fluorescence in frozen sections establish that the lobular distribution of constitutive hepatic microsomal cytochrome P-450 is qualitatively heterogeneous and may be altered during hepatocellular responses to chemical treatment.

Animals↗
PubMedDate not supplied

Noninvasive blood pressure performance: a reproducible method for quantifying motion artifact tolerance in oscillometry.

Motion artifact tends to degrade oscillometric noninvasive blood pressure measurement (NIBP) accuracy and other aspects of performance (measurement time, patient comfort, false-positive readings). Medical personnel generally have not fully appreciated the extent of these degradations, in part because NIBP provides no waveform display to allow visualization of artifact disruption (unlike the electrocardiography (ECG) and pulse oximetry (SpO2) patient channels). More importantly, the magnitude and frequency of NIBP errors has also gone unappreciated because the auditory noise produced by transport vibration prevents accurate quantification of NIBP accuracy by the traditional auscultatory method. To overcome these problems, a commercially available NIBP simulator was modified to permit the superimposition of repeatable motion artifact waveforms from a function generator onto known patient blood pressure profiles available in the NIBP simulator. The superimposed artifact waveforms had been collected under transport conditions. This methodology enabled comparisons between artifact-free NIBP readings, on the one hand, and artifact-contaminated readings on the other. Monitors under test were subjected to multiple combinations of patient and artifact profiles. Measurement errors were expressed as a percent deviation of the artifact-contaminated readings from the expected (artifact-free) readings. Statistical analyses of the data compared the performance of the different monitor types with nonparametric tests of inference (Kruskal-Wallis H test, Mann-Whitney U test, and chi-squared test). These analyses demonstrated statistically significant differences in performance including accuracy, yield (incidence of values within various error categories), retries, measurement time, and false-positive readings under artifact-only conditions. The method further demonstrated that the monitor using ECG synchronization to filter motion artifact achieved statistically and clinically significant improvements in accuracy without compromising clinical expectations for measurement time. This approach provided a reproducible and quantifiable method by which to assess and differentiate the artifact tolerance of different NIBP technologies.

Artifacts↗
PubMedDate not supplied

Immunohistochemical evidence for alterations in specific forms of rat hepatic microsomal cytochrome P-450 during acute carbon tetrachloride intoxication.

The response of specific forms of hepatic microsomal cytochrome P-450 to carbon tetrachloride was studied by immunohistochemical techniques in order to assess the localization and specificity of action for this hepatotoxin. Liver sections were taken from control, phenobarbital-pretreated, and 3-methylcholanthrene-pretreated male rats that had received acute (3 hr) treatment with carbon tetrachloride. The liver sections were examined after indirect immunofluorescent labeling with anti-P-450un, anti-P-450a, anti-P-450b, and anti-P-450c. Diminished fluorescence and loss of intracellular homogeneity of fluorescence were found in the centrilobular cells of liver sections from control rats incubated with anti-P-450un, anti-P-450a, and phenobarbital-pretreated, carbon tetrachloride-challenged rats incubated with anti-P-450b. In liver sections from 3-methylcholanthrene-pretreated, carbon tetrachloride-challenged rats incubated with anti-P-450c, fluorescence was diminished in periportal cells but did not show loss of intracellular homogeneity. These results provide immunohistochemical evidence for the differential effect of carbon tetrachloride on specific forms of cytochrome P-450.

Animals↗
PubMedDate not supplied

Immunohistochemical localization of cytochrome P-450a in liver sections from untreated rats and rats treated with phenobarbital or 3-methylcholanthrene.

Antibodies against cytochrome P-450a purified from hepatic microsomes of Long-Evans rats were used for indirect immunofluorescent localization of cytochrome P-450a within the livers of untreated, phenobarbital-treated, and 3-methylcholanthrene-treated mature and immature male and female rats. Immunohistochemical localization of cytochrome P-450a in liver sections from untreated mature male rats revealed fluorescence primarily in the central and midzonal regions, and moderate fluorescence in the periportal region. This pattern of fluorescence was not significantly altered in liver sections from mature male rats treated with phenobarbital or 3-methylcholanthrene. Liver sections from untreated mature female and immature male and female rats were primarily fluorescent in the central region with weak fluorescence in the midzonal and periportal regions of the lobule. Phenobarbital or 3-methylcholanthrene treatment markedly enhanced the intensity and lobular distribution of the fluorescence in liver sections from mature female and immature male and female rats. The apparent induction of cytochrome P-450a in the mature female and immature male and female rats, but not in mature males, is consistent with our previous immunochemical studies on the quantity of cytochrome P-450a in hepatic microsomes from untreated and treated rats. In addition, this study demonstrates that the lobular distribution of cytochrome P-450a in untreated mature male rats is different from the distribution of cytochrome P-450a in untreated female or immature rats.

Animals↗
PubMedDate not supplied

Contextual factors associated with disturbing behaviors in institutionalized elders.

Data from a longitudinal clinical trial funded by the National Institute of Aging, testing the effects of staff education and consultation on restraint reduction in nursing homes, were used to examine disturbing behaviors in institutionalized elders and to identify related environmental and personal characteristics. Subjects were 586 residents from three well-matched nursing homes. Kayser-Jone's (1989) model on environment and quality of life in long-term care institutions served as the organizing framework. Data on disturbing behaviors from the Psychogeriatric Dependency Rating Scale were factor analyzed. Three factors, Agitated Psychomotor Behaviors, Aggressive Interpersonal Communication, and Expressive Difficulty, emerged from the principal factor analysis and accounted for 35% of the variance. The Kayser-Jones model partially explained Agitated Psychomotor Behavior (R2 = .22). A model comparison approach indicated that the addition of an organizational variable, staff mix, significantly increased the amount of variance explained over and above that contributed by the personal variables.

Aged↗