"Dream deprivation": effects on dream content

Dream content elicited following the selective deprivation of rapid-eye-movement sleep was intensified compared to that elicited under nondeprivation conditions. This effect was observed both for repressers and for sensitizers, but was significant only for repressers. On nondeprivation nights, the dream periods of sensitizers were shorter and their dreams more intense than those of repressers.     

Carbon monoxide measurements in the troposphere

During the second flight of the space shuttle, the measurement of air pollution from satellites (MAPS) experiment in the OSTA-1 payload acquired approximately 35 hours of radiometric measurements of the carbon monoxide mixing ratio in the middle troposphere, upper troposphere, and lower stratosphere. A gas filter radiometer operating in the 4.67-micrometer band was used to acquire the data over the region from 38 degrees N to 38 degrees S during both daytime and nighttime. The performance of the measurement system was excellent. The data reduced to date indicate the presence of significant gradients in the middle tropospheric carbon monoxide mixing ratio with both latitude and longitude over the North Atlantic, the Mediterranean Sea, and the Middle East. On the basis of comparisons with directly measured values, the accuracy of the measurements is approximately 15 percent. Comparisons of data taken on successive orbits over the same geographic region indicate that the repeatability of the measurements is approximately 5 percent.     

Effects of delay in reapplication of nitrogen fertilizer following cutting silage from a ryegrass sward

Plots of a 2-year-old sward of Merlinda perennial ryegrass received a routine dressing of 100 kg N ha⁻¹ as compound fertilizer in March 1991, followed by further dressings of 100 kg N ha⁻¹ after cuts 1, 2 and 3 in a simulated four-cut silage system, either the same day as cutting or with a delay of 3, 7, 10 or 14 d. Partial irrigation ensured that fertilizer could be taken up immediately. Annual total dry matter yield, the dry matter yield for the experimental cuts 2–4 and their apparent response to N showed no effect of delays of 0–10 d in reapplication of fertilizer, but a significant ( P < 0·01) reduction for 14 d delay. Significantly ( P = 0·001) higher apparent recovery of N in the cut herbage was recorded where reapplication of fertilizer had been delayed by 7 or 10 d (93% and 91% respectively) in comparison with either smaller (0 delay, 78%; 3 d delay, 87%) or greater delay (14 d, 86%). It is suggested that lower recoveries at 0 and 3 d result from the sward's reduced NO₃ uptake following defoliation and that, while in practical situations the conditions may not be as rigorous as those imposed in this experiment, further experiments to determine the fate of N not recovered in the herbage are warranted, so defining management circumstances in which immediate reapplication of N might not be advisable.     

The effect of cooking methods on the lipid composition of potatoes

The effect of boiling and baking in either a convential or microwave oven on the lipid content of potatoes was investigated. The crude lipid content of potatoes was lowered significantly by all methods of cooking. The loss was highest in potatoes cooked in a microwave oven, least in boiled tubers, and intermediate in tubers baked in a conventional oven. Similar trends were observed for both cortex and pith tissues. Generally, the phospholipid content followed the same trend as the crude lipid, the exception being the cortex tissue of tubers baked in the conventional oven, in which the greatest loss of phospholipid occurred. Cooking did not significantly alter the fatty acid composition of tubers. A possible relationship between the degree of cell rupturing, known to be influenced by different mechanisms of heat transfer, and the amounts of tuber lipid associated with different cooking methods was discussed.     

Canine CYP2B11 metabolizes and is inhibited by anesthetic agents often co-administered in dogs

Baratta, M. T., Zaya, M. J., White, J. A., Locuson, C. W. Canine CYP2B11 metabolizes and is inhibited by anesthetic agents often co-administered in dogs. J. vet. Pharmacol. Therap. 33 , 50–55.
Medetomidine is a well-established sedative and analgesic for dogs and cats. As a premedicant for anesthesia regimens that also include other agents, medetomidine can also provide a dose-sparing effect. While there are likely several reasons for the dose-sparing effect of medetomidine, the role of metabolic drug–drug interactions at the single enzyme level has not yet been examined. Using a panel of individually expressed canine cytochromes P450 cloned from beagle liver, this report demonstrates that medetomidine is an extremely potent CYP2B11 inhibitor (IC₅₀ < 10 n m ) and that ketamine and midazolam are CYP2B11 substrates with high intrinsic clearances. These in vitro findings suggest that under some circumstances, medetomidine (i.e. 'perpetrator') may inhibit the metabolic clearance of some high metabolic clearance drugs (i.e. 'victims') with which it is commonly co-administered via the CYP2B11 pathway. However, as the dose-sparing effect of medetomidine premedication commonly results in anesthetic dose reduction, any increased plasma concentrations of victim drugs caused by medetomidine would still be lower than if no dose reduction had been made. Further studies are needed to characterize whether medetomidine possesses the potential to cause pharmacokinetic interactions. In conclusion, the ability of recombinant P450s to define canine-specific drug clearance pathways and P450 inhibitors should prove useful in identifying drug combinations that may require dose adjustments in dogs.     

Refinement of an orthotopic lung cancer model in the nude rat

Over 85% of people with lung cancer eventually succumb to this disease, largely because current chemotherapies are ineffective. The testing and validation of promising new approaches generally rely on achieving responses with cell lines in vitro or in tumor xenografts in nude mice. However, quite often the results seen with these models are not recapitulated in the clinic, thus necessitating the need for better animal models of lung cancer for preclinical testing of new therapies. One promising model is that of orthotopic lung cancer, where xenografts of human lung cancer are established in lungs of immunodeficient rodents. The problems associated with this model include poor rates of engraftment, limited tumor multiplicity, and a heightened risk for surgical trauma. The purpose of our study was to develop an efficient approach to engraftment of orthotopic tumors throughout the lungs of the Rowett nude rat. Initially, we augmented immunosuppression in the rats with whole-body X-irradiation and then used orotracheal cannulas to intratracheally instill human cancer cells from the Calu-6 cell line. This protocol produced a low rate of engraftment and low tumor multiplicity. The hypothesis that slight disruption of the pulmonary epithelium or the surfactant layer would allow better tumor engraftment was tested by coadministration of either pancreatic elastase or ethylenediaminetetraacetic acid (EDTA) along with the cell instillations. Lung tumor engraftment was evaluated 8 weeks after instillation. The inclusion of elastase or EDTA with the Calu-6 cells resulted in an 80-100% engraftment rate, respectively. Coadministration of EDTA resulted in significantly larger and greater numbers of tumors/lung than those in elastase-treated animals. Temporal studies demonstrated that small nodules were scattered throughout the lung parenchyma 5 weeks after instilling Calu-6 cells and EDTA. These nodules grew to coalesce and form large masses that effaced >75% of the parenchyma at 9 weeks postinstillation. The refinements made through our studies have led to the development of an orthotopic lung cancer model that should facilitate the evaluation of novel therapies designed to treat or impede lung cancer development.