PubMed Health⌕ Search

Biomedical subjects

T Larson

Publications and source records attributed to T Larson.

44 records · Page 3Linked to original sources
PubMed1982

Assay of netilmicin, using enzyme immunoassay for gentamicin.

A homogenous enzyme immunoassay for the quantitative determination of netilmicin in serum was developed. The procedure utilizes a commercially available assay for gentamicin (EMIT; Syva Co., Palo Alto, Calif.). The method was adapted to a microcentrifugal analyzer, and log-logit regression analysis was performed with a computer. The results of samples assayed by this method correlate well with microbioassay (r2 = 0.985) and radioimmunoassay (r2 = 0.986). This method is not only precise and accurate, but also very rapid and economical and compares favorably to other available methods of netilmicin assay.

Gentamicins↗
PubMed1982

sn-Glycerol-3-phosphate transport in Escherichia coli and Salmonella typhimurium.

The gene necessary for the synthesis of the active transport system of sn-glycerol-3-phosphate (G3P) is located at 48 min on the Escherichia coli linkage map. Complementation analysis revealed that there is only one gene necessary for G3P transport. The gene was cloned into the multicopy plasmid pBR322. Strains harboring the hybrid plasmid synthesized large amounts of a protein of 33,000 molecular weight that was found in the cytoplasmic membrane. This protein was identified as the G3P permease. In addition, the periplasm of the hybrid plasmid carrying strain contained large amounts of a soluble protein, identical with the previously recognized GLPT-protein of 40,000 molecular weight. The analysis of amber mutants isolated on the hybrid plasmid showed that the gene for the G3P permease is the first gene in an operon that codes for two genes; the distal gene being the structural gene for the periplasmic GLPT-protein. The corresponding gene region from Salmonella typhimurium has been cloned from an EcoRI libary in lambda gt7. The EcoRI fragment containing the gene necessary for G3P transport was subcloned into the multicopy plasmid pACYC184. The hybrid plasmid directed the synthesis of the G3P permease that behaved identically to the protein from Escherichia coli. However, the gene for the GLPT-protein was not intact but truncated by the EcoRI restriction site. The synthesis of the remaining polypeptide of 30,000 prevented the proper assembly of other transport related binding proteins such as the ribose- and galactose-binding protein.

Biological Transport↗
PubMed1980

The chemical neutralization of inhaled sulfuric acid aerosol.

We hypothesize that gaseous ammonia (NH3) released into respiratory airways can neutralize inhaled acidic particles and alter or mitigate their toxicity. To test this hypothesis, we have examined the relationship between respiratory NH3 and the chemical neutralization of inhaled sulfuric acid (H2SO4) aerosol in the surgically isolated upper airways of anesthetized dogs. With air entering via the mouth, the NH3 concentration measured at the larynx, ranged between 30 and 225 parts per billion (ppb). The extent of neutralization at this point ranged from 8%-70% (n = 16) for the 0.5-micrometer particles and 7%-22% (n = 16) for the 1.0-micrometer particles. With air entering via the nose, the laryngeal NH3 concentrations ranged between 50 and 220 ppb. Neutralization values were between 15%-65% (n = 8) for 0.5-micrometer particles, and between 16%-18% (n = 3) for 1.0-micrometers particles. For both routes of entry, the extent of neutralization was correlated with the laryngeal NH3 concentration. We conclude that the chemistry of acidic particles is significantly altered by respiratory NH3 during inhalation. The extent of neutralization is related to both the NH3 concentration in the airway and the size of the particle entering the airway. The extent of neutralization per ppb of laryngeal NH3 is related to the route of entry, being greater for the mouth than the nose.

Aerosols↗
PubMedDate not supplied

Spatial and temporal measurements of NO2 in an urban area using continuous mobile monitoring and passive samplers.

This paper describes the use of a continuous mobile monitor and passive samplers to estimate the spatial distribution of NO2 in an urban area for the purpose of siting a continuous monitor to measure population exposure. Monitoring sites were sites selected based on the State and Local Air Monitoring Stations (SLAMS) and National Air Monitoring Station (NAMS) siting criteria required by the U.S. Environmental Protection Agency (U.S. EPA). SLAMS monitoring objectives define scales in which the NO2 concentration and land use are homogeneous. The SLAMS scales relevant to NO2 monitoring for NAMS NO2 monitoring sites are neighborhood (0.5 to 4 km), and urban (several to 50 km). SLAMS siting objectives also define four categories of sites: highest concentration, representative concentration, impacts of major sources, and background sites. Mobile monitoring with a Scintrex LMA-3 luminal monitor was used on a neighborhood scale to measure the NO2 concentration at sites that covered a large geographical area. Passive samplers were then located at candidate mobile monitoring locations for long-term sampling which covered the neighborhood to the urban scale. These two methods complement each other by combining short-term continuous measurements and integrated long-term measurements which reflect the National Ambient Air Quality Standard for NO2 which is based on an annual average. The neighborhood site with the highest concentration was not only in the area of highest population density, but was also representative of the larger urban scale. The magnitude of this urban scale is approximately 20 km.

Air Pollutants↗