John G. Mohler

Effects of exposure of blood hemoglobin to nitric oxide

The effect of oxygen exposure on nitrosylhemoglobin of whole human blood or its buffered solution has been determined. The amount of methemoglobin formed was determined by an anaerobic modification of the Evelyn-Malloy method; 59% of the total hemoglobin of whole blood was oxidized to methemoglobin in the first 15 min of the oxygen exposure and 78% of the total hemoglobin was oxidized after 120 min of oxygen exposure. Similar results were obtained when nitrosylhemoglobin buffered solutions were exposed to the oxygen of the air. A comparison of the present in vitro results with these obtained by injecting nitric oxide into the rat peritoneal cavity and its implications are discussed.

Human Health Effects of Air Pollutants

Eight adult male volunteers were exposed to ozone (O3) alone and then in combination with nitrogen dioxide and carbon monoxide under conditions simulating ambient air pollution exposures. Four “normal” men showed few or no effects from repeated exposures. Four male volunteers with a history of “hyperreactive” airways, but with normal base line pulmonary function spirometric studies, after O3 exposure developed definite symptoms and decrement in pulmonary function.

In vitro methemoglobin formation in human blood exposed to NO2.

The in vitro formation of methemoglobin in human blood was determined for various NO2 concentrations and exposure times. Blood was exposed either to measured amounts of NO2 in air or to a continuous flow of known concentrations of NO2 in air. CO2 was added to the gas phase to maintain pH and PCO2 in a normal range. Exposure to 45 ppm NO2 oxidized 95% of the total hemoglobin (THb) in 5 hr. Six ppm NO2 oxidized 17% of THb in 3 hr. Differences between in vitro and in vivo NO2 results are discussed.

Failure of the serum CO2 determined by automation to estimate the plasma bicarbonate

In the daily care of pulmonary disease patients, we have often encountered large differences in the bicarbonate value calculated from blood gas determination pCO2 and pH, and the serum CO2 obtained from the Dupont Automatic Clinical Analyzer (ACA). Realizing that many clinicians utilize the automated measurement of serum CO2 ([CO2]s) in place of blood gas determinations, we felt it necessary to analyze paired sets of ACA [CO2]s and blood gas bicarbonate values ([HCO3-]p) for variations which might lead to clinically significant differences in interpretation. A study of 1,841 patient samples, matched by date and within +/- 2 hours of sampling, and supported by a thorough chart review of 100 randomly selected patients, indicates that a statistically significant difference, which is unrelated to apparent changes in the patient clinical status, does exist. Evaluation of pK changes due to temperature failed to correct these differences in serum CO2 and plasma bicarbonate. Based on the limited information available in the literature, as well as the strict quality control measures utilized in the measuring of [CO2]s using the ACA method and the measurement of bicarbonate by blood gas determination, we have concluded that the differences in the [CO2]s and [HCO3-]p can only be related to erroneous assumptions about the method of measuring [CO2]s by the ACA or other automated methods as well as manual techniques of back titration.

Nonautocatalytic methemoglobin formation by sodium nitrite under aerobic and anaerobic conditions

Aerobic exposure of human hemoglobin in 1:1 molar ratio to sodium nitrite induced an immediate and progressive formation of methemoglobin. Neither lag nor autocatalytic phases were observed, contrary to what was seen when diluted hemoglobin in buffered solutions was used. Hemolyzed whole blood, washed red cells with their plasma replaced by saline, and whole blood were exposed to identical sodium nitrite concentrations. In the presence of oxygen, the speed of methemoglobin formation was three to four times faster in the hemolyzed and plasma-free samples than in whole blood. The maximum rate was reached within the first minute of the reaction. Restoring plasma to washed red cells reduced the rate to that of whole blood; restoring plasma to hemolyzed red cells had no effect on rate. We advance the hypothesis that sodium nitrite or its derivatives form a complex with some element of the blood plasma which slows the passage of nitrite through the red cell membrane without hindering the oxidative capacity of the nitrite. With no free oxygen present, whole blood, washed red cells in saline, and hemolyzed blood all showed a similar rate of methemoglobin formation when exposed to a 1:1 molar ratio of sodium nitrite. The presence of nitrosylhemoglobin formed in the anaerobic reaction seems to be a for the lack of changes seen in the reaction.

The oxygen deficit and debt for normal and non-athletic men

We have (1) demonstrated that the O2 deficit (VO2 Df) and O2 debt (VO2Dt) can both be described as linear relations to the intensity of steady state exercise; (2) demonstrated that the O2 debt varies widely with seemingly small analytical error; and (3) there is considerable confusion in the literature as to the value to be expected for the VO2 Dt or VO2Df. We found that neither the O2 debt nor the O2 deficit is related to age or body surface area, except as these measurements are reflected in the VO2 exercise. We have compared the oxygen debt and the oxygen deficit for a given stint of work and have demonstrated that above about one L/m of vO2 there is an increasingly greater O2 debt-deficit difference which could be accounted for in large measure to analytical error as well as errors of the basic assumptions and definitions of the VO2 Df and the VO2Dt. Finally, we have compared our results with published results, and find only one grouping of the data. We did find several reports whose results agreed with ours; several did not. The latter did not form a second grouping of data but varied widely.

An Unusual Source of Error in Measuring [Vdot]o2

Adding oxygen (O2) to an exercise laboratory at a rate of about 14 liters/min produced an atmosphere with a measurably higher O2 concentration (FO2 ≈ 0.2110) than normal ([FlO2 ] = 0.2093). Assuming FlO2 to be 0.2093 instead of its actual value led us to calculate an erroneously small [vdot]O2 consumption ([vdot]O2).

Chronic diaphragmatic hernia. A difficult diagnosis.

Chest pain is commonly caused by disorders of the heart, lungs, and chest wall. Pinpointing the exact cause is often a diagnostic challenge. In this article, the authors describe the evaluation and treatment of a patient with sharp chest pain of unusual origin.

Oxides of Nitrogen

OXIDES OF NITROGEN Elemental nitrogen, N2, is a colorless gas that composes 78% of air by volume. Elemental oxygen is the other major component of air, composing 21%. Nitrogen can be separated from air by chilling the air until it condenses to a liquid, and then allowing the liquid to boil. Liquid nitrogen will boil off first at –196 C (77 K), leaving behind liquid oxygen, which boils at a higher temperature of –183C (90 K).