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Biomedical subjects

P A Larson

Publications and source records attributed to P A Larson.

15 recordsLinked to original sources
PubMed1987

Evaluation of ECG gating for selective intraarterial carotid DSA.

A study comparing ECG-gated and nongated acquisition for selective carotid digital subtraction arteriography was performed on 116 bifurcations in 63 patients. For ECG acquisition, three exposures (systole, early diastole, and late diastole) were obtained for each cardiac cycle. There was no significant difference in the frequency of plaque misregistration between gated (18%) and nongated (23%) acquisitions. In gated studies, the frequency of plaque misregistration was equivalent in systole, early diastole, and late diastole. Gated and nongated studies provided equivalent image quality for selective carotid digital subtraction angiographic studies.

Carotid Arteries↗
PubMed1987

Evaluation of ECG gating and hybrid subtraction for intraarterial digital subtraction thoracic aortography.

A comparative study was made of ECG-gated and nongated intraarterial digital subtraction angiography of the thoracic aorta by using conventional temporal subtraction and combined temporal/energy (hybrid) subtraction. ECG-gated studies were acquired at three frames per cardiac cycle. In 85% of patients, gated conventional subtraction resulted in studies of superior image quality in comparison with those obtained with hybrid techniques, both gated and nongated. In the 15% in whom hybrid subtraction studies were judged superior, the hybrid images were almost exclusively integrated by video frame averaging and thus were nongated. In a separate subset of patients who had conventional nongated studies, there was no difference in the percentage of diagnostic studies (93%) and nondiagnostic studies (7%) when compared with conventional gated temporal subtraction. Cardiac gating appears to be superior to hybrid subtraction for studies of the thoracic aorta that use intraarterial digital subtraction angiography, but neither technique offered any significant advantage over conventional nongated acquisition.

Aged↗
PubMed1983

Transmission of tuberculosis by flexible fiberbronchoscopes.

The development of flexible fiberoptic bronchoscopy was an important technologic advance in the diagnosis and management of patients with pulmonary disease. However, reliable decontamination and sterilization of these delicate instruments have been difficult. Many physicians routinely use a solution of povidone-iodine diluted in 70% ethyl alcohol and water to decontaminate fiberbronchoscopes, despite the fact that these iodophor compounds were developed as skin antiseptics and not as germicidal disinfectants for decontaminating instruments. We isolated a strain of Mycobacterium tuberculosis on a surveillance culture from a bronchoscope after it had been cleaned and disinfected with an iodophor solution. In another hospital, we documented the transmission of M. tuberculosis from one patient to another by a bronchoscope that had been disinfected with a commonly recommended iodophor solution. We then studied the tuberculocidal efficacy of various iodophor preparations used with exposure times from 10 to 30 min. In several experiments these iodophors failed to kill M. tuberculosis. Because iodophors do not reliably kill M. tuberculosis, they should not be used to disinfect fiberoptic bronchoscopes.

Adult↗
PubMed1977

Effect of local or parenteral application of ACTH or hydrocortisone on bovine corpus luteum function.

Studies were conducted to determine the effect on corpus luteum (CL) function of ACTH or hydrocortisone administered by ovarian perfusion on day 11 of the oestrous cycle or by carotid infusion on days 2-9 of the oestrous cycle. No significant local effects on CL function were observed during the ovarian perfusion study. Continuous carotid infusion of ACTH or hydrocortisone on days 2-9 resulted in a decreased slope of the progesterone increase during the infusion period. However, no difference in plasma progesterone level on days 9-11 between control and treated cycles was detected and there was no difference between treated and control CL at day 11 with regard to CL weight or progesterone content. The data suggest a possible direct effect of hydrocortisone on either the hypothalamus or pituitary which results in decreased progesterone secretion but not CL development. No residual effect was observed.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Nurse perceptions of patient characteristics.

To determine whether nurse perceptions of patients are influenced by a patient's socioeconomic class, 78 nurse subjects observed slides and read about a patient and then rated him on a seven-point scale. Nurses were randomly given one of eight written descriptions in which the patient was identified as middle or lower class., with a more or a less serious and a more or a less socially acceptable illness. Results were subjected to 2 X 2 X 2 analysis of variance. Nurses were found to stereotype lower-class patients as dependent, passive, unintelligent, noncomprehending, ummotivated, lazy, forgetful, inaccurate, careless, uninformed, unsuccessful, and unreliable. Patients with less-acceptable illnesses were rated more negatively than those with more-acceptable illnesses and were perceived as sensitive, rigid, bored, and resistant to learning about their illness. Since nurses admitted they would feel embarrassed and would conceal having these less-acceptable illnesses themselves, these negative perceptions of patients may be projections of the nurses' feelings.

Alcoholism↗
PubMedDate not supplied

Improved codistillation method for determination of carbon tetrachloride, ethylene dichloride, and ethylene dibromide in grain and grain-based products.

A method is described for the determination of the common fumigants carbon tetrachloride (CCl4), ethylene dichloride (EDC), and ethylene dibromide (EDB) in grain and grain-based products. A properly prepared sample is mixed with water and hexane, an internal standard mixture of 1,2-dichloropropane (DCP) and 1,2-dibromopropane (DBP) is added, and the fumigants are codistilled with the hexane into an appropriate receiver. After the hexane solution is dried over sodium sulfate, the quantities of fumigants present are quantitated on a gas chromatograph (GC) equipped with an electron capture detector (ECD). For the matrices investigated, the relative standard deviation of the method was 6.0, 9.7, and 23.1% for CCl4, EDC, and EDB, respectively. Recoveries of added fumigants were 107, 95, and 101%, respectively. Comparison with an acetone-water soak extraction method gave a correlation of 0.967 between methods for EDB with odds of a difference between methods of 35%.

Carbon Tetrachloride↗
PubMedDate not supplied

Headspace gas chromatographic method for determination of methyl bromide in food ingredients.

A headspace gas chromatographic (GC) method, which can be automated, has been developed for determination of methyl bromide. This method has been applied to wheat, flour, cocoa, and peanuts. Samples to be analyzed are placed in headspace sample vials, water is added, and the vials are sealed with Teflon-lined septa. After an appropriate equilibration time at 32 degrees C, the samples are analyzed within 10 h. A sample of the headspace is withdrawn and analyzed on a gas chromatograph equipped with an electron capture detector (ECD). Methyl bromide levels were quantitated by comparison of peak area with a standard. The standard was generated by adding a known amount of methyl bromide to a portion of the matrix being analyzed and which was known to be methyl bromide free. The detection limit of the method was 0.4 ppb. The coefficient of variation (CV) was 6.5% for wheat, 8.3% for flour, 3.3% for cocoa, and 11.6% for peanuts.

Arachis↗
PubMedDate not supplied

Rapid determination of deoxynivalenol (vomitoxin) by liquid chromatography using modified Romer column cleanup.

A modification of the Romer method for determining deoxynivalenol (DON) provides rapid sample cleanup and includes liquid chromatographic (LC) quantitation. The method was evaluated using wheat, wheat flour, and other wheat products. The sample is extracted with acetonitrile-water (84 + 16), and an aliquot of the extract is subjected to activated charcoal-alumina column chromatography. The extract is then evaporated and diluted to volume with mobile phase, and DON is quantitated using liquid chromatography. The relative standard deviation based on duplicate samples is 6.07%. The detection limit is 30 ppb based on 2 X signal/noise ratio. Results by this method compared with the results obtained by the Scott GC method showed a correlation coefficient of 0.992 with a mean vomitoxin content of 779 ppb by this method and 716 ppb by the Scott method for 14 samples.

Chromatography, Liquid↗
PubMedDate not supplied

Gas chromatographic determination of total fat extracted from food samples using hydrolysis in the presence of antioxidant.

A method for the quantitative measurement of total fat in foodstuffs is described. Fat is extracted by hydrolysis and inter-esterified to fatty acid methyl esters for gas chromatographic analysis. Total fat and fatty acid patterns are calculated to comply with the regulations for food label declaration under the Nutrition Labeling and Education Act of 1990. Quantitative recovery of fat from soy oil is obtained in the presence of the antioxidant pyrogallol. Extraction and measurements of fat from a variety of food samples (e.g., cereal, baked goods, dairy, and fish) are also reported, and fat levels ranged from 0.8 to 95% (w/w). Coefficients of variation of < or = 5% demonstrate the efficiency of the method.

Chromatography, Gas↗