Estimating surface NO2 and SO2 mixing ratios from fast-response total column observations and potential application to geostationary missions

Total-column nitrogen dioxide (NO₂) data collected by a ground-based sun-tracking spectrometer system (Pandora) and an photolytic-converter-based in-situ instrument collocated at NASA's Langley Research Center in Hampton, Virginia were analyzed to study the relationship between total-column and surface NO₂ measurements. The measurements span more than a year and cover all seasons. Surface mixing ratios are estimated via application of a planetary boundary-layer (PBL) height correction factor. This PBL correction factor effectively corrects for boundary-layer variability throughout the day, and accounts for up to ≈75 % of the variability between the NO₂ data sets. Previous studies have made monthly and seasonal comparisons of column/surface data, which has shown generally good agreement over these long average times. In the current analysis comparisons of column densities averaged over 90 s and 1 h are made. Applicability of this technique to sulfur dioxide (SO₂) is briefly explored. The SO₂ correlation is improved by excluding conditions where surface levels are considered background. The analysis is extended to data from the July 2011 DISCOVER-AQ mission over the greater Baltimore, MD area to examine the method's performance in more-polluted urban conditions where NO₂ concentrations are typically much higher.

Naltrexone dampens ethanol-induced cardiovascular and hypothalamic- pituitary-adrenal axis activation

Alcohol ingestion activates the autonomic nervous system and the hypothalamic-pituitary-adrenal axis. This study examined naltrexone effects on alcohol-induced increases in physiological responses and their association with alcohol liking. Using a within-subjects design, heavy drinking men (N = 19) were maintained on each of three naltrexone doses (0, 50, and 100 mg, p.o.) over an 8-day inpatient stay. Within each naltrexone dose, subjects had three alcohol challenge sessions (none, moderate, high) in random order. Autonomic, subjective and endocrine measurements were collected regularly prior to and following alcohol administration. High-dose alcohol ingestion increased heart rate, diastolic blood pressure, skin temperature, ACTH, cortisol and liking of drink effects; responses following the moderate alcohol dose were less consistent. Naltrexone significantly dampened alcohol-induced increases in heart rate, diastolic blood pressure, hormone levels and subjective liking of drink effects. This dampening of cardiovascular and hormonal responses may contribute to the therapeutic effectiveness of naltrexone for reducing alcohol liking and decreasing relapse in alcohol-dependent persons.

Increased mu opioid receptor binding detected by PET in cocaine-dependent men is associated with cocaine craving

The endogenous opioid system has been recently implicated in the reinforcing actions of cocaine and other addictive drugs. In this study we examined mu opioid receptor binding in ten cocaine-dependent men and seven nonaddicted controls using positron emission tomography and [11C] carfentanil. Mu opioid binding was increased in several brain regions of the cocaine addicts studied 1-4 days after their last use of cocaine. Binding was positively correlated with the severity of cocaine craving experienced at the time. The upregulation of mu opioid receptor binding persisted after 4 weeks of monitored cocaine abstinence. These findings demonstrate for the first time the involvement of the endogenous opioid system in cocaine dependence and cocaine craving in living human subjects.

Scavenging anesthetic gas from a membrane oxygenator during cardiopulmonary bypass

Concerns remain about the acute and chronic effects on personnel of waste anesthetic gases in the operating room environment. This study demonstrates a simple and effective means of scavenging waste anesthetic gases when halogenated anesthetics are administered through the pump oxygenator during cardiopulmonary bypass. This technique safeguards workers' health by reducing ambient anesthetic levels below the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limits.

Acetaldehyde inhibits serum aminopeptidases

Aminopeptidase A (APA)- and aminopeptidase M (APM)-like activity were assayed in Moni-Trol ES with L-alpha-aspartyl-beta-naphthylamide and L-alanyl-beta-naphthylamide, respectively. Upon preincubation of the serum with 89.4, 223.5, and 447 mM acetaldehyde at room temperature for 30 min, a reduction in 26.8%, 55.3%, and 75.8% aminopeptidase A activity was observed. Similarly, aminopeptidase M activity was reduced by 26.5% and 53.1% upon preincubation with 223.5 and 447 mM acetaldehyde. Ethanol at 84.9, 212.3, and 427.9 mM did not significantly affect the enzymic activity. Because aminopeptidase A and aminopeptidase M also degrade the pressor substance, angiotensin II, it is suggested that inhibition of aminopeptidase A- and aminopeptidase M-like activity by acetaldehyde, the product of ethanol metabolism, may lead to higher levels of circulating angiotensin II and, consequently, hypertension, in alcoholics. The hydrolysis of lysine-p-nitroanilide, an aminopeptidase B substrate, was also inhibited upon addition of acetaldehyde to Moni-Trol ES serum.

The effect of halothane/nitrous oxide/oxygen mask induction on arterial hemoglobin saturation in cyanotic heart disease

The effect of a halothane/nitrous oxide/oxygen mask induction on arterial hemoglobin saturation (SaO2) was studied in 25 patients with cyanotic congenital heart disease. During this induction the SaO2 increased from 80% +/- 2 (mean +/- SEM) in awake patients breathing room air to 86% +/- 1 after induction of anesthesia, with an average increase of 6.8% +/- 2 (absolute) (N = 25; P < .005). Patients were retrospectively divided into two groups, A and B. Group A patients had pulmonic infundibular stenosis (PIS) (N = 13) with the potential for variable pulmonary outflow tract obstruction. These patients had awake SaO, values of 76% +/- 3 that increased significantly after induction to 86% +/- 1, with an average increase of 10% +/- 4 (absolute) (P < .01). Group B patients did not have PIS; they had an awake SaO2 of 83% +/- 2, which rose insignificantly after induction to 87% +/- 1, with an average increase of 4% +/- 2 (absolute) (P > .1). Thus, the significant increase in SaO2 during induction for the entire group was primarily due to the large response of patients with PIS. No correlation was found between SaO2 and systolic blood pressure for the entire study population as well as for groups A and B separately. The lack of correlation between systolic blood pressure and SaO2 may indicate that relaxation of pulmonic infundibular stenosis is an important mechanism explaining the observed increase in SaO2 during anesthetic induction in group A (PIS) patients. Six patients had clinically important decreases in SaO2 during the induction of anesthesia, and airway obstruction was usually the cause. Anesthetic induction with halothane/nitrous oxide/oxygen leads to an increase in SaO2 in patients with many forms of cyanotic heart disease, but especially those with the potential for variable pulmonary outflow tract obstruction.