Gas-Liquid Chromatographic Method for the Analysis of Microencapsulated Ethyl Parathion and Methyl Parathion Insecticides: Collaborative Study

The determination of ethyl parathion in Penncap-E insecticide was studied collaboratively by 14 laboratories. The assay of methyl parathion in Penncap-M insecticide was studied by 8 laboratories. The original method which was adopted official first action for methyl parathion specified dimethoate, which is currently classified as a suspected carcinogen, as the internal standard. The current collaborative efforts were conducted as a supplemental study to evaluate the performance of the new internal standard, bis-2-methoxyethyl phthalate, and to test the gas-liquid chromatographic method for microencapsulated ethyl parathion (internal standard, dibutyl phthalate). The method uses essentially the same grinding and extraction with acetonitrile as the original study. At the 20% methyl parathion level, the standard deviation within laboratories was 0.186%, and among laboratories, 0.737%. Two formulations of ethyl parathion at approximately 16 and 24% were analyzed in replicate on 2 days by the same analyst, and provided excellent agreement within laboratories as well as among laboratories. The standard deviation (pooled) within laboratories was 0.284% and among laboratories, 0.518%. The method has been adopted as official first action.

Efficient method for determining the glycyrrhizin content of fresh and dried roots, and root extracts, of Glycyrrhiza species

A reliable and efficient method suitable for the selective analysis of the glycyrrhizin content of fresh and dried roots of Glycyrrhiza species and of root extracts is described. The method was optimised for recovery and analysis of glycyrrhizin after conversion to its aglycone, 18 beta-glycyrrhetinic acid. The reversed-phase HPLC system was developed using a sterically protected C8 column that allowed UV detection of the aglycone at 254 mm without interference from co-occurring components. The average recovery through the method was determined at 83%, with a range of 65-99%. Analysis of 150 dried root samples gave levels of glycyrrhizin consistent with earlier reported values. A comparison of post-harvest treatment conditions. showed that the drying of root samples at up to 65 degrees C did not result in any measurable reduction in glycyrrhizin.

Sertl shelf arthroplasty (BOP procedure) in the treatment of canine hip dysplasia

The BOP/Sertl shelf arthroplasty procedure is not difficult or lengthy. It uses minimal metallic fixation. It is quite physiological with minimal morbidity because there is no change in the bony anatomic pelvis except to create an extension of the lateral rim of the acetabulum. The animal is able to walk the day after surgery. The procedure can be performed bilaterally the same day, thus creating good bony stability and decreasing stretching of the joint capsule, which in turn prevents further subluxation and pain in the hip joint. The aim of this procedure is to return the animal to a satisfactory lifestyle through an effective but less complicated surgical procedure as compared to other available options. This procedure is straightforward and can be done by a surgeon who is familiar with orthopedic surgical techniques and has been trained in this procedure. To date, more than 150 veterinarians have had hands-on training to perform this operation. We are not claiming that this procedure is a cure for CHD; rather, it is a procedure that dramatically slows down the progress of this malady and allows the dog to lead a more normal lifestyle and avoids euthanasia. After 51 months, our study of 200 hips has had a success rate of 99% on the animals available for follow-up as evidenced by returning those animals to a satisfactory lifestyle with stable hips.

Reduction of pulsed gradient settling time in the superconducting magnet of a magnetic resonance instrument

The implementation of electronic compensation for eddy currents to reduce the gradient settling times on a superconducting magnet is described. Field plots inside the magnet indicate the importance of assessing the field changes at several positions in the magnet. The effect of an asymmetry between the gradient coil system and the cryostat is demonstrated. A modified compensation circuit is described to overcome this mechanical asymmetry.

Magnetic resonance imaging of experimental mumps meningoencephalitis in suckling hamsters

Mumps virus-infected and normal newborn hamster brains were imaged with magnetic resonance (MR) within 24 h after birth and serially scanned. Hydrocephalus developed explosively on Day 6 postinfection and progressed until death occurred soon after Day 10. This study demonstrates the utility of MR in the investigation of experimental viral encephalitis in very small laboratory animals.

Pulse sequence design for volume selective excitation in magnetic resonance

The design of a pulse sequence for volume localization in magnetic resonance spectroscopy is described in detail. The sequence is based on the volume selective excitation technique (VSE) proposed by Aue et al. [J. Magn. Reson. 56, 350 (1984)] and overcomes the high rf power requirements of VSE. The implications of various design stages are demonstrated experimentally and by computer simulations.