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Biomedical subjects

D G Oliver

Publications and source records attributed to D G Oliver.

10 recordsLinked to original sources

Transesophageal defibrillation: animal studies and preliminary clinical observations.

Ventricular fibrillation (VF) that fails to respond to transthoracic defibrillation leaves the clinician with few alternatives. The purpose of this study was to develop a technique of rescue defibrillation by use of transesophageal electrodes. Fourteen anesthetized dogs (20-30 kg) were investigated in this study. Two electrodes (300 mm2) were mounted 8 cm apart on an esophageal probe and inserted approximately 40 cm from the mouth. VF was induced using AC current delivered to the myocardium. Defibrillation was then performed between the distal electrode (anode) and anterior skin patch (cathode). After 15 seconds of induced VF, transesophageal and transthoracic defibrillation thresholds (DFTs) were determined in random order. The esophageal DFT (90 +/- 15 joules) tended to be lower than the transthoracic DFT (115 +/- 35 joules), though this difference was not statistically significant. One dog could not be defibrillated by transthoracic defibrillation but responded to transesophageal defibrillation. Esophageal electrodes were also useful for arrhythmia discrimination and ventricular pacing (pacing threshold of 38 +/- 5 mA at a pulse duration of 2.5 msec). Following transesophageal DFT determination, in ten dogs (total energy of 600 +/- 150 joules), acute esophageal histopathology demonstrated mild to severe focal injury to the mucosa and/or muscular layers. However, esophagi in four chronic dogs (total energy of 470 +/- 110 joules) showed no gross evidence of mucosal damage, perforation, or stricture 4 weeks following defibrillation. Histopathology showed only focal myocyte atrophy and repair. As a last resort, transesophageal defibrillation was performed in the emergency room on four patients with out-of-hospital refractory VF who failed > 6 high energy transthoracic shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Detection of Salmonella dublin mammary gland infection in carrier cows, using an enzyme-linked immunosorbent assay for antibody in milk or serum.

An ELISA has been developed for measurement of milk and serum IgG concentrations directed against Salmonella dublin. Four groups of cows were studied: group A--7 experimentally challenge-exposed cows (infected, recovered group); group B--6 normal uninfected randomly selected control cows; group C--7 naturally occurring S dublin carrier cows; and group D--6 normal uninfected S dublin negative cows from the same herd as group C. Group-A cows were inoculated orally, or inoculated orally and then IV, but none became a S dublin carrier. As expected, all 7 group-A cows responded with a marked increase in ELISA titer after oral exposure to virulent S dublin, starting with a mean serum titer of 17.7% and reaching a peak mean serum titer of 79.3% approximately 76 days after initial exposure. As determined by necropsy and organ culturing of the remaining cows, none of the group-A cows became carriers. The mean serum ELISA titer for group-B uninfected control cows was 14.1% (SD +/- 12.8%). The mean milk ELISA titer was -1.0% (SD +/- 5.5%). Colostrum and then milk gave false-positive results for up to 2 weeks after onset of lactation. Group-B cows were culture negative for S dublin in feces and milk during lactation, and when tissues were cultured after euthanasia. Milk and serum samples for ELISA, and milk and fecal samples for culturing were taken from all group-A and -B cows twice a week for 6 months. Statistical correlation (P less than 0.05) was found between serum and milk ELISA titers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Competitive solid phase enzyme-linked immunoassay for the quantification of limonin in citrus.

A solid-phase enzyme immunoassay for the quantitative determination of the bitter triterpene-lactone, limonin, in citrus juice samples is described. As little as 0.1 ppm of limonin can be detected. Quantitative results are available within 1 h of total assay time. The assay makes use of a limonin-alkaline phosphatase tracer of high immunoreactivity and has been semiautomated using antibody-coated polystyrene microcuvettes, a vertical light path photometer, and a forced-air microplate incubator.

Alkaline Phosphatase↗

Enzyme-linked immunosorbent assay for the detection of toxoplasmosis in swine: interpreting assay results and comparing with other serologic tests.

An enzyme-linked immunosorbent assay (ELISA) was developed for the serodiagnosis of swine toxoplasmosis. The results of the ELISA were interpreted as percentage (% ELISA) and ELISA titer and were compared with results of the dye test, indirect fluorescent antibody test, and indirect hemagglutination test. The results obtained from both the % ELISA and ELISA titer directly correlated with the dye test results. The ELISA is a rapid, sensitive, and readily performed serologic test that should be ideal for examining (screening) swine for toxoplasmosis.

Animals↗

Liquid crystal thermography. A method for monitoring temperature gradients in microtitration plates.

Precise quantitative heat transfer information in microtitration plates can be obtained by filling the wells of a microtitration plate with cholesteric liquid crystals and incubating the plates at the desired temperature in different incubators. The liquid crystals indicate temperature by changes in discrete reproducible colors over various temperature ranges. With these instrumented plates, interwell thermal gradients may be documented visually and are in close agreement with results obtained by using wire thermocouple measuring techniques.

Cholesterol↗

Thermal gradients in microtitration plates. Effects on enzyme-linked immunoassay.

Temperature studies of microtitration plates demonstrate that the use of a common bacteriology incubator for heating the plates can cause a phase log of over 30 min for the fluid in the wells to reach 37 degrees C from ambient temperature, and that a temperature gradient of as much as 1.6 degree C can exist between the peripheral and center wells. This gradient is a cause of the "rim" of edge effect noted in enzyme immunoassay using microtitration plates. The problem is corrected by the use of a specially designed forced air microtitration plate incubator.

Enzyme-Linked Immunosorbent Assay↗

Hope for the future.

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Forecasting↗