Isoflurane to prolong medetomidine/ ketamine anaesthesia in six adult female chimpanzees (Pan troglodytes).

Six adult female chimpanzees (Pan troglodytes) were anaesthetised for the placement of intrauterine contraceptive devices, microchips for identification, routine blood sampling, and physical measurements. Anaesthesia was induced with medetomidine in combination with ketamine administered by intramuscular injection with a projectile syringe. Induction was smooth and rapid, but five of the animals were insufficiently relaxed for orotracheal intubation. The plane of anaesthesia was deepened by administering isoflurane delivered in oxygen and nitrous oxide, and general anaesthesia was maintained for up to 74 minutes. The action of medetomidine was reversed at the end of each procedure with atipamezole, and the animals recovered smoothly and uneventfully.

The fate of diesel hydrocarbons in soils and their effect on the germination of perennial ryegrass.

Hydrocarbon contamination in soils may be toxic to plants and soil microorganisms and act as a source of groundwater contamination. The objective of this study was to evaluate the fate of diesel in soils with or without added nutrients. The soils examined either had or had not a previous history of hydrocarbon contamination. Particular aspects examined were soil respiration, changes in microbial population, breakdown of diesel hydrocarbons, and phytotoxicity to the germination of perennial ryegrass. Soil respiration was measured as evolved CO2. Bacterial population was determined as colony forming units in dilution plates and fungal activity was measured as hyphal length. The fate of individual hydrocarbons was determined by gas chromatography-mass spectrometry after extraction with dichloromethane. When diesel was added to soil with no previous history of hydrocarbon contamination at rates up to 50 mg/g, the respiration response showed a lag phase of 6 days and maximum respiration occurred at day 11. The lag phase was 2 days and maximum respiration occurred at day 3 in soil with a previous history of hydrocarbon contamination. After the peak, respiration decreased up to about 20 days in both soils. Thereafter, respiration become more or less constant but substantially greater than the control. N and P addition along with diesel did not reduce the lag phase but increased the respiration over the first 20 days of incubation. Diesel addition with or without N and P increased the bacterial population 10- to 100-fold but fungal hyphal length did not increase. Diesel addition at a rate of 136 mg/g did not increase the microbial population. Removal of inhibition to germination of perennial ryegrass was linked to the decomposition of nC10 and nC11 hydrocarbons and took from 11 to 30 days at diesel additions up to 50 mg/g depending on the soil. Inhibition to germination of perennial ryegrass persisted to more than 24 weeks at the 136 mg/g of diesel addition.

Does steroid medication reduce facial edema following face lift surgery? A prospective, randomized study of 30 consecutive patients.

A prospective, double-blinded study of 30 consecutive face lift patients was conducted to determine if the administration of corticosteroid medication would reduce postoperative facial edema. Half the patients received steroid medications in a random fashion. Three independent plastic surgeons who were blinded to the study rated facial swelling by comparing preoperative and postoperative photographs using a scale of 1 to 4. The data were tabulated and subjected to statistical analysis. There were no significant differences in facial swelling between the steroid-treated group and the untreated patients on any occasion.

Comparison of rechargeable lithium and nickel/cadmium battery cells for implantable circulatory support devices.

Size and weight constraints are critical areas in the design of implantable medical devices. For this reason, a study of different rechargeable lithium and nickel/cadmium (Ni/Cd) battery cell types was undertaken to determine which cell type, when assembled into a multicell battery pack, would provide the smallest and lightest power source for implantation. The discharge rate and cycle life characteristics of 2 different rectangular prismatic Ni/Cd cells and 5 different rechargeable lithium cells were determined at 37 degrees C by charge/discharge cycling, the cells using a constant discharge load of 0.87 A. Using the observed discharge rate and cycle life characteristics of the cells, along with the desired performance criteria of 30 min operating time at the end of a 1-year implant period, the projected weight and volume of the various 12-V battery packs were determined. These results showed that one of the rectangular prismatic Ni/Cd cells would yield the smallest (53 ml) and lightest (189 g) 12-V battery pack that met the performance criteria specified. The results also indicate that, for applications requiring long implant times, cycle life can be more important in the selection of cells for a small, lightweight battery pack than specific energy or energy density.

The effect of pulsatile power loads on nickel/cadmium battery cells for mechanical circulatory support devices.

A number of portable medical devices, including the implantable ventricular assist device, demand fluctuating or pulsatile power from their batteries. Therefore, a study was undertaken to determine the effects of these pulsatile discharge loads on the cycle life and operating time of rectangular prismatic nickel/cadmium battery cells. The battery cells were charge/discharge cycled at 37 degrees C using either a pulsatile discharge load of 10.0 or 11.25 W (average) or a nonpulsatile discharge load equivalent to the average of the pulsatile loads. The tests showed that the pulsatile discharged cells gave significantly less operating time throughout their cycle life, by a mean of 3 +/- 3-8 +/- 2 min on each cycle (ie, 8 +/- 8-18 +/- 5%), compared to the cells under equivalent nonpulsatile discharge loads. The tests also showed that the pulsatile discharged cells had significantly shorter cycle lives, by 61-97 cycles (11-17%), than the nonpulsatile discharged cells. The results show that, under the test conditions of this study, pulsatile discharge loads reduce the cycle lives and operating times of rectangular prismatic nickel/cadmium battery cells, compared to cells discharged under nonpulsatile loads of equivalent average power.

Evaluation of nickel-cadmium battery packs for mechanical circulatory support devices.

The mismatching of battery cell capacities within a rechargeable battery pack can result in reduced cycle life and operating time, as well as an increased safety risk due to gas release, which is a concern when used in implantable medical devices, such as a ventricular assist device (VAD). Two groups of four nickel/cadmium (Ni/Cd) battery packs containing 10 cells each (i.e., 12 volt packs) were evaluated for their cycle life, safe operating time, and the impact of mismatched cell capacities within the pack. Four control battery packs containing capacity matched cells (within +/- 0.4% of mean) and four battery packs each containing one low capacity cell (4.7-10.7% below mean) together with nine high capacity matched cells (within +/- 0.6% of mean) were charge/discharge cycled at 37 degrees C using a 9.7 W average pulsatile discharge load and a 30 minute discharge time on each cycle. Periodically, the battery packs were fully discharged down to 10 volts and each cell was monitored for negative voltages. The capacity matched and mismatched packs yielded similar performance curves, with an initial decline in mean total operating time until a plateau was reached of 41.1 +/- 1.5 and 41.8 +/- 1.8 minutes of discharge time, respectively. The mean total operating times of the matched and mismatched packs began to decline again after approximately 670 and 635 cycles, respectively. Cell voltage monitoring showed no negative voltages, indicating that no gases were released from the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo solvent-suppressed localized hydrogen nuclear magnetic resonance spectroscopy: a window to metabolism?

Solvent-suppression NMR techniques are combined with a pulsed magnetic field gradient and surface coil detection method of spatial localization. The result is a technique that enables observation of metabolites in the hydrogen (1H) NMR chemical-shift spectra from preselected disk-shaped volumes of biological tissue in vivo. Localized spectra are recorded from the normal human brain and forearm and from a dog in acquisition periods of 2 s using a 1.5-T imaging/spectroscopy system. This is several hundred-fold faster than acquiring similar state-of-the-art 31P NMR spectra of brain metabolites in vivo. Spectroscopy experiments are followed by conventional surface coil imaging sequences to precisely define the selected volume. Contamination of spectra by lipid resonances is a problem.