Search PubMed⌕ Search

Biomedical subjects

C A Riley

Publications and source records attributed to C A Riley.

9 recordsLinked to original sources
PubMed1994

Preliminary experience with magnetic resonance venography: comparison with findings at surgical exploration.

While conventional magnetic resonance imaging has been described for the evaluation of the venous system, we have recently developed the technique of magnetic resonance venography (MRV), which generates three-dimensional projection venograms. Our purpose was to determine if MRV reliably images the venous system by comparison with findings at surgical exploration. Thirteen of fourteen consecutive patients undergoing bypass surgery (26 limbs) were studied by 2D time-of-flight MRV preoperatively from the inguinal ligament to the ankle bilaterally. The average examination time was 50 min. The size and quality of each saphenous vein were recorded at the saphenofemoral junction, mid-thigh, knee, mid-calf, and malleolus. Intraoperatively the quality and size of each vein were measured in situ and when distended by saline. Twelve veins were of good quality. MRV predicted this in every case. One vein, found to be recanalized, had an abnormally thick wall noted on MRV. MRV measurements of average vein size were intermediate between that of the in situ and distended vein and correlated most closely with the distended vein (R = 0.74, P < 0.001). The superficial and deep femoral veins and lesser saphenous veins were routinely visualized by MRV; thus a complete map of all available vein was obtained by a single study. It is concluded that MRV is an accurate method of venous imaging as confirmed by findings at operative exploration. This new technique holds promise as a noninvasive method for evaluation of the venous system and warrants further investigation.

Coronary Artery Bypass↗
PubMed1986

Simultaneous analysis of antipyrine and lorazepam by high-performance liquid chromatography.

A novel analytical methodology was developed for simultaneous high-performance liquid chromatographic quantitation of antipyrine and lorazepam in biological fluids using phenacetin and flunitrazepam as internal standards, respectively. A gradient solvent system was used to achieve specificity and sensitivity for each of the compounds in biological fluids. The between-run coefficients of variation for replicate analysis of antipyrine and lorazepam in identical plasma samples were 9.4 and 6.4% at 60 micrograms/ml and 5.5 micrograms/ml, respectively, for antipyrine, and 9.1 and 9.9% at 110 ng/ml and 10.5 ng/ml, respectively, for lorazepam. Accuracy ranged from 99.7 to 101.4% at concentrations of 8, 45 and 105 micrograms/ml for antipyrine and from 94.8 to 95.8% at concentrations of 12, 55 and 125 ng/ml for lorazepam. This method requires only one organic extraction procedure for all four compounds, allows quantitation of these two drugs in samples also containing indocyanine green, and sample throughput following extraction is totally automated.

Antipyrine↗
PubMed1985

Loop-column extraction and liquid chromatographic analysis of doxorubicin and three metabolites in plasma.

A sensitive and specific high performance liquid chromatographic method for the separation and quantitation of doxorubicin and three metabolites is described. The new method involves isocratic reversed-phase separation of these compounds, with quantitation by either electrochemical or fluorescence methods. A novel loop-column method was used to extract the compounds of interest from plasma, eliminating the need for organic extraction of biological samples before injection into the chromatographic system. The limit of sensitivity with the fluorescence method was about 2.3 ng on column. Sensitivity with electrochemical detection was better, although there was more interference by early eluting plasma components. The between-run CV (%) for replicate analysis of doxorubicin in identical plasma samples was 2.0 at 112.5 ng/ml, 5.4 at 40.0 ng/ml, and 9.9 at 14.0 ng/ml. Precision for each of the three metabolites was comparable. Accuracy for doxorubicin and each metabolite ranged from 93 to 107% at concentrations of 14.0, 40.0, 65.0, 112.5, and 140.0 ng/ml. The new loop-column extraction method, with injection of plasma samples directly onto the chromatograph, is simpler and more efficient than previous methods requiring organic extraction, making it more feasible for routine processing of clinical samples.

Chromatography, High Pressure Liquid↗
PubMed1982

Quantitation of daunorubicin and its metabolites by high-performance liquid chromatography with electrochemical detection.

A selective and sensitive high-performance liquid chromatographic method was developed for the separation and quantitation of daunorubicin and its metabolites in serum, plasma, and other biological fluids. Daunorubicin and metabolites in human plasma were injected directly into the high-performance liquid chromatography system via a loop-column to pre-extract the drugs from the plasma, and quantitated against a multilevel calibration curve with adriamycin as the internal standard. The column effluent was monitored with an electrochemical detector at an applied oxidative potential of 0.65 V and by fluorescence. Daunorubicin and four metabolites were separated and characterized by this method. In a blinded evaluation of accuracy and precision, the mean coefficients of variation were 3.8, 3.6 and 9.8% at concentrations of 150, 75 and 15 ng/ml, respectively, and blank samples gave negligible readings. The amperometric sensitivity was greater than achieved by fluorescence detection, and offers an alternative method for quantitation of these compounds. The new method has a limit of detection of less than 2 ng on column, allowing quantitation of less than 10 ng/ml in plasma samples without organic extraction prior to chromatographic analysis.

Chromatography, High Pressure Liquid↗
PubMed1979

Large bronchial casts.

Unusually large bronchial casts developed in four patients. In two, the casts were associated with pneumonia. In one, a large RBC cast resulted from a complication of fiberoptic bronchoscopy. Bronchial casts developed in an additional patient as a manifestation of plastic bronchitis. Although unusual, bronchial cast formation may complicate a number of hypersecretory pulmonary diseases. Therapy ordinarily includes specific measures to treat the underlying disease state and maneuvers designed to remove or facilitate the expectoration of bronchial casts.

Adult↗
PubMed1968

Successive reversals of a classically conditioned heart-rate discrimination.

Rats were trained to criterion in successive reversals of a classically conditioned heart-rate discrimination. Criterion was attained more rapidly in the later reversals in the series than in the early reversals and the inter-problem learning curve was of the same general form as that found with successive instrumental discrimination reversal in the same species.

Animals↗
PubMedDate not supplied

Acute respiratory failure: a rare complication of perfusion photoscintigraphy in a patient with bullous emphysema.

Acute cardiorespiratory failure occurred in a patient with advanced bullous emphysema following perfusion photoscintigraphy with radiolabeled macroaggregated albumin. Complications of perfusion photoscintography are rare. However, in patients with advanced pulmonary vascular disease, special precautions may decrease the minimal hazard associated with perfusion photoscintigraphy.

Aged↗