A micrometeorological technique to monitor total hydrocarbon emissions from landfarms to the atmosphere.

Landfarming is used to treat petroleum hydrocarbon-contaminated soils and a variety of waste streams from industrial operations. Wastes are applied to a soil surface and indigenous soil microorganisms utilize the hydrocarbons in the applied waste as a carbon source for metabolism, thereby biodegrading the applied material. Concerns have been expressed that abiotic losses, such as volatilization, play a significant role in hydrocarbon reduction within the soil. To assist in better defining atmospheric releases of total hydrocarbons from landfarms treating petroleum hydrocarbons, a flux gradient micrometeorological approach was developed and integrated with a custom-built total hydrocarbon detector, and a novel air sampling system and averaging algorithm. The micrometeorological technique offers unobtrusive spatially averaged real-time continuous measurements, thereby providing a time history of emissions. This provides opportunities to investigate mechanisms controlling emissions and to evaluate landfarm management strategies. The versatility of the technique is illustrated through measurements performed at a remote landfarm used to treat diesel fuel-contaminated soil in northern Ontario and during routine operations at two active refinery landfarms in southwestern Ontario.

Does nifedipine enhance the cardiovascular depressive effects of bupivacaine?

Inadvertent intravenous administration of bupivacaine has been shown to cause cardiovascular collapse in patients. Patients undergoing peripheral vascular surgery have a high incidence of coronary artery disease and frequently receive calcium channel antagonists such as nifedipine for treatment of angina. In this study, the effects of an accidental intravenous injection of bupivacaine during regional anesthesia in patients taking nifedipine was simulated using dogs. The sling-trained dogs had baseline hemodynamic values recorded. Each dog was given a 10-mg sublingual loading dose of nifedipine in alcohol solvent followed by intravenous infusion of nifedipine at a rate of 5/micrograms/kg/min. After hemodynamic measurements were taken, increasing boluses of intravenous bupivacaine were administered until a 50% decrease in maximum left ventricle change in pressure with respect to time (LV dP/dt max) was observed. On the next day of the experiment, baseline hemodynamic measurements were recorded. The dog was given only the alcohol solvent portion of the nifedipine solution at a dosage and rate equivalent to that of the first day of the experiment. Next, increasing boluses of intravenous bupivacaine were administered exactly as on the first day until a 50% decrease in LV dP/dt max was observed. The results demonstrated that the total dose of bupivacaine given with nifedipine (8.7 +/- 3.7 mg/kg) to reach a 50% drop in LV dP/dt max was significantly less than the total dose of bupivacaine given without nifedipine (14.5 +/- 4.9 mg/kg); and the main effect of the combination of nifedipine and bupivacaine was to accentuate the decrease in LV dp/dt max caused by bupivacaine with the elimination of the compensatory increase in systemic vascular resistance to maintain blood pressure.

Natriuretic and smooth muscle responses to human urinary natriuretic hormone in rats: relation to blood pressure and kallikrein excretion in patients.

Human urine contains a small molecular weight natriuretic substance and similar material isolated from the kidney inhibits Na/K ATPase. Such action on smooth muscle in blood vessels would cause contraction. Human urinary natriuretic material caused contraction of the smooth muscle in the rat anococcygeus muscle and this activity correlated with its natriuretic activity. Known vasoactive substances could not explain the activity of the natriuretic factor when tested on the anococcygeus muscle. The best correlation with blood pressure of the patient was with the log of the ratio of natriuretic activity divided by the kallikrein excretion. A normotensive woman with severe renal failure had very high kallikrein excretion as well as increased natriuretic activity and her data fitted the same correlation as the hypertensives' data.

Serotypes of Yersinia pseudotuberculosis recovered from domestic livestock.

The serological identity of 234 strains of Yersinia pseudotuberculosis recovered from domestic animals and birds in New Zealand was determined by slide agglutination test. Thirty strains were also examined by tube agglutination test. The strains were isolated from cattle (56), sheep (8), deer (117), goats (13), pigs (7), rabbits (6), guinea pigs (5), and aviary species of birds (22). All strains were isolated from animals or birds which had died or shown signs of ill health and amongst which diarrhoea was a common feature. Serotype I accounted for 23% (53) of strains, serotype II for 13% (30) of strains and serotype III for 64% (151) of strains. It was concluded that further investigations on the prevalence and serological identity of strains recovered from clinically healthy animals mav provide useful information in assessing the significance of various serotypes as a cause of disease in livestock.