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Biomedical subjects

J H Bates

Publications and source records attributed to J H Bates.

At least 181 records · Page 10Linked to original sources
PubMed1983

Correcting for the dynamic response of a respiratory mass spectrometer.

Mass spectrometers produce distorted measurements of gas concentrations because of the time delays and rise times inherent in their responses. Three techniques for numerically correcting such distortion were applied to the acetylene step responses of a Perkin-Elmer MGA1100 mass spectrometer and to simulated data. The techniques investigated were 1) a simple time-delay correction, 2) an exponential model method that assumes a biexponential form for the peak of the impulse response, and 3) a Fourier transform method of deconvolution known as Wiener filtering. The time-delay correction produced an order of magnitude reduction in measurement error. The exponential model method improved on the time-delay correction, and the Wiener filter gave the most accurate corrections in all cases examined.

Fourier Analysis↗
PubMed1981

The extent of reflux of unconjugated 14C-cholic acid from the liver in subjects with normal liver function.

An improved understanding of bile acid physiology is a prerequisite for the construction of an acceptable model for describing plasma clearance of bile acids. The aim of this study was to determine the extent of reflux unconjugated cholic acid from the liver to the plasma in subjects with normal liver function. The clearance of a bolus injection of unconjugated 14C-cholic acid was studied in four subjects using samples collected simultaneously from a peripheral and a hepatic vein. Hepatic extraction ratios calculated directly from the data were found to be essentially constant during the 20 min following injection, with average values of 0.60-0.72. This indicates that reflux did not occur significantly in the subjects investigated. These results are interpreted as favouring a model in which exchange of unconjugated 14C-cholic acid occurs between the plasma and a peripheral compartment with final removal from the plasma to the liver.

Carbon Radioisotopes↗
PubMed1981

Evidence for plasmid-mediated restriction-modification in Mycobacterium avium intracellulare.

Mycobacterium avium intracellulare strain LR25 carries three plasmids with molecular weights of 11.2, 18.3 and 107 X 10(6) as determined by electron microscopy. A number of phages propagated on Mycobacterium smegmatis ATCC 607 were tested for their ability to infect strain LR25. Phage JF2 gave an efficiency of plating of 10(-4) on strain LR25, but phage JF2 propagated on strain LR25 infected strain LR25 and M. smegmatis with equal high efficiency. This indicated the presence of a restriction-modification (R-M) system in strain LR25 that was not present in M. smegmatis. Strain LR25 was grown in the presence of acriflavine to eliminate the plasmids and tested for sensitivity to phage JF2. One of forty colonies was found to be R-M-deficient. This strain, designated strain LR163, lacks the three plasmids present in strain LR25. The results indicate that the R-M system is plasmid-coded. Strain LR163 was sensitive to several phages to which strain LR25 was resistant and for which we were unable to isolate modified phage. This suggests that some plasmid-coded function in addition to restriction is involved. An R-M system was also demonstrated in M. avium intracellulare strain LR131 using phage JF1. This strain does not carry plasmids.

Bacteriophage Typing↗
PubMed1981

Phage typing of the Mycobacterium avium-intracellulare-scrofulaceum complex.

Because of the need for additional criteria for characterizing strains of the M. avium-intracellulare-scrofulaceum (MAIS) complex the practicality of phage typing was examined. We developed a satisfactory method for plaque assays with these organisms using the soft-agar overlay technique with Dubos oleic acid-albumen agar. Cells were cultured in 7H9 broth enriched with oleic acid-albumen complex and glycerol. A number of available phages and 2 phages recently isolated from soil were tested for their ability to infect various MAIS strains. Phages AN9, AN3, AN1-8, D302, VA6, VC3, D32, JF1, JF2, JF3, and JF4 were selected for preliminary typing. All of the phages were propagated on M. smegmatis. Sixty-one MAIS strains having 29 different serotypes were tested and 33 were sensitive to at least 1 phage. Of 17 M. avium strains (serotypes 1, 2, and 3), 16 were phage-sensitive. Considerable diversity in patterns of phage lysis was observed, and the patterns of lysis did not coincide with serotype. Although we do not yet have a formal phage typing scheme, our results indicated that the MAIS strains are suitable for phage typing.

Bacteriolysis↗
PubMed1980

Treatment of tularemia, including pulmonary tularemia, with gentamicin.

An alternative to streptomycin for treatment of possible tularemia would be useful on occasions when a patient develops a perplexing pneumonia that does not respond to initial treatment. In geographic areas where tularemia is endemic, an antimicrobial drug that is bactericidal for Francisella tularensis and is also effective against a spectrum of common pulmonary pathogens, including the Enterobacteriaceae and most strains of Pseudomonas aeruginosa, would be desirable. The purposes of this report are (1) to describe observations regarding the in vitro susceptibility of Francisella tularensis to streptomycin, kanamycin, and gentamicin; (2) to describe in vivo efficacy of these drugs in mouse tularemia; (3) to describe the results in 10 patients with tularemia treated with gentamicin. Gentamicin was bactericidal for Francisella tularensis in vitro, was effective in mouse tularemia when given in large doses, and was effective in humans when given in the standard recommended dose.

Aged↗
PubMed1979

Isolation of plasmids from mycobacteria.

A procedure for preparing sodium dodecyl sulfate-salt-cleared lysates of mycobacteria was developed. Standard techniques were employed to demonstrate covalently closed circular deoxyribonucleic acid in lysates of nine strains of Mycobacterium avium-intracellulare.

DNA, Bacterial↗
PubMed1979

Rapid definitive diagnosis of Legionnaires' disease.

We describe a sporadic case of Legionnaires' disease in which the diagnosis was made by direct immunofluorescence of material obtained by percutaneous aspiration of the involved lung via a needle. Employment of this technique among selected patients with suspected Legionnaires' disease would provide for more rapid diagnosis and more prompt initiation of definitive therapy for some patients.

Aged↗
PubMed1979

Thermoregulatory failure secondary to acute illness: complications and treatment.

We report on six patients in whom hypothermia secondary to acute illnesses, including pneumonia, congestive heart failure, renal failure, drug overdose, and hypoglycemia, developed. Complications that occurred were metabolic acidosis in six patients, altered sensorium in five, bradyarrhythmia in three, and hyperamylasemia in two. All patients failed to demonstrate a shivering response and represent cases of acute thermoregulatory failure. Five of the six patients survived. In the course of treatment, the choice of active or passive rewarming should be based on whether or not normal thermoregulatory mechanisms are intact.

Acute Disease↗
PubMed1978

Biochemical and morphological characterization of mycobacteriophage R1.

Large-scale propagation of mycobacteriophage R1 in broth culture has allowed the isolation of quantities of virus sufficient for characterization of its nucleic acid and lipid components as well as investigation of its ultrastructural attributes. Analysis of R1 DNA indicates that it is double stranded and possesses a molecular weight of 2.5 X 10(7) and a guanine-plus-cytosine content of 65.7 +/- 0.5%. The lipid fraction of R1 accounts for 14% of the total dry weight of the virus, 20% of which was identified as free or esterified sterols. A rapid loss of viral titer occurred after seconds of exposure to organic solvents. This result suggests that the lipid fractions of R1 is essential for its infectivity. Electron microscopic investigation of solvent-extracted R1 showed extensive deterioration of its normal morphology, including nucleocapsid disintegration and base plate separation. Routine phosphotungstate preparations demonstrated a particle with an oval head and a noncontractile tail. Altering the pH of the phosphotungstate negative stain from neutrality damage the viral particles. Uranyl formate-contrasted specimens displayed an elongated hexagonal nucleocapsid with a neck region; the cross-striated tail possessed a starlike base plate.

Cytosine↗