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The chemical reactivity of several minerals thought to be present in Martian fines is tested with respect to gases known in the Martian atmosphere. In these experiments, liquid water is excluded from the system, environmental temperatures are maintained below 0 degrees C, and the solar illumination spectrum is stimulated in the visible and UV using a Xenon arc lamp. Reactions are detected by mass spectrometric analysis of the gas phase over solid samples. No reactions were detected for Mars nominal gas over sulfates, nitrates, chloride, nontronite clay, or magnetitie. Oxidation was not observed for basaltic glass, nontronite, and magnetite. However, experiments incorporating SO2 gas--an expected product of volcanism and intrusive volatile release--gave positive results. Displacement of CO2 by SO2 occurred in all four carbonates tested. These reactions are catalyzed by irradiation with the solar simulator. A calcium nitrate hydrate released NO2 in the presence of SO2. These results have implications for cycling of atmospheric CO2, H2O, and N2 through the regolith.
J Mol Evol 1979 Dec
PMID:Heterogeneous phase reactions of Martian volatiles with putative regolith minerals. 52 62

1. The respiratory response to inhaled 3% and 6% CO2 was measured in 10 normal subjects after a 3 h acclimatization period to 3% CO2 in an environmental chamber. Control studies were carried out after a 3 h period of breathing air in the chamber. 2. At the end of the acclimatization period studies were carried out during 20 min periods breathing 3% CO2, 6% CO2 and air. 3. At 2-min intervals during the studies measurements were made of tidal volume (Vt), breathing frequency (fR), minute ventilation (Ve), viscous pulmonary rate of work (Wp) and total viscous rate of work across the lungs and apparatus (Wt). Blood gas tensions were measured at the end of this period. 4. After acclimatization to 3% CO2 there was a significant shift in the response curves Ve/Pa,CO2 and Wt/Pa,CO2 such that subjects showed higher Pa,CO2 values for given values of Ve or Wt. There was no significant change in the slope of the response curves. 5. No correlation was found between the slope of the response curve after the control period breathing air and the degree of shift of the response curve. 6. There was no difference in respiratory pattern or in pulmonary resistance. 7. Similar results were found in two subjects studied after 24 h acclimatization to 3% CO2 but one subject also showed a significant change in the slope of the Ve/Pa,CO2 curve.
Clin Sci Mol Med 1978 Sep
PMID:The respiratory response to inhaled carbon dioxide in man after 3 hours exposure to 3% carbon dioxide. 69 7

1. To study the validity of a CO2-rebreathing method at rest and during graded exercise, cardiac output was measured simultaneously on 59 occasions in 16 subjects with normal pulmonary function with the CO2-rebreathing method and the direct Fick method for oxygen. The correlation coefficient between the results of both methods was significantly higher during exercise than at rest. 2. No systematic difference was shown between (a-v)CO2 content difference determined on whole blood and end-tidal gas, which justified the exclusion of a correction factor for blood to alveolar gas PCO2 gradients. 3. In the calculation of cardiac output by the direct Fick method for CO2 and by CO2 rebreathing, a standard CO2 dissociation curve was preferred to a synthetic CO2 dissociation curve, constructed by allowance for changes in haemoglobin concentration, pH and oxygen saturation. The latter curve tended to increase values for cardiac output and induced a large dispersion around the line of identity, when compared with simultaneous cardiac output estimates by the direct Fick method for oxygen.
Clin Sci Mol Med 1978 Nov
PMID:Comparison of cardiac output determined by a carbon dioxide-rebreathing and direct Fick method at rest and during exercise. 71 98

1. The effect on respiration of a single dose of propranolol has been studied in normal subjects. 2. The degree of beta-adrenoreceptor blockade was assessed in terms of the impaired heart-rate response to progressive exercise and the plasma propranolol concentration. 3. No effect of propranolol was demonstrated on either the ventilatory response to rebreathing CO2 in hyperoxia, or the response to progressive isocapnic hypoxia. Simple indices of maximal expiratory flow (FEV 1.0% and PEFR) were also unchanged. 4. The absence of any effect of propranolol on the chemical control of breathing in man is discussed in relation to the conflicting literature.
Clin Sci Mol Med 1978 Nov
PMID:Propranolol and the ventilatory response to hypoxia and hypercapnia in normal man. 72 3

1. A new open-circuit respiratory method was developed to estimate mixed venous PCO2 more rapidly and accurately than is possible with rebreathing techniques. 2. The subject breathes a mixture of CO2 in air from an open circuit. Carbon dioxide is added to the air flowing through the circuit at a rate such that the PCO2 in the inspired and expired gases (recorded continuously with a CO2 analyser) are almost identical. 3. Results from respiratory and cardiac patients showed that equilibrium occurred in less than 10 s. There was good agreement between the tensions of CO2 in the respiratory plateaux and in mixed venous and arterial blood withdrawn during equilibrium. 4. During exercise, the tensions of CO2 of the plateaux and arterial blood at equilibrium also showed good agreement. 5. It is suggested that the new method represents an improvement over rebreathing methods as equilibrium is achieved rapidly before the mixed venous tension rises from recirculation.
Clin Sci Mol Med 1977 Apr
PMID:A new open-circuit method for estimating carbon dioxide tension in mixed venous blood. 86 33

1. The concentration of metabolites in intercostal and quadriceps muscle, and pulmonary function, were studied in twelve patients with chronic obstructive lung disease and acute respiratory failure before, during and after standardized treatment at an intensive care unit. The findings were compared with those obtained in hospitalized patients of comparable age with non-pulmonary diseases. 2. On admission, when the patients had marked hypoxaemia, hypercapnia and acidosis, the concentrations of ATP and creatine phosphate were low in both intercostal and quadriceps muscle, particularly the latter. The lactate concentration was increased in relation to control values but glycogen did not differ significantly. 3. In response to therapy, the Pa,CO2 and the patient's acidosis decreased, the vital capacity increased and lung mechanics improved along with the clinical condition. At the same time there were significant increases in the concentrations of ATP, creatine phosphate and glycogen in intercostal and quadriceps muscles, to values similar to, and for glycogen in excess of, those found in control subjects. Lactate concentration fell significantly during treatment. 4. In view of the low initial muscle concentrations of ATP and creatine phosphate in the patients, it is suggested that dysfunction of the respiratory muscles may be an important component of respiratory failure. Moreover, the concentration of energy-rich compounds in muscle rose significantly as the patients responded to treatment, which emphasizes the importance of adequate nutritional therapy in this disorder.
Clin Sci Mol Med 1977 Apr
PMID:Muscle metabolism in patients with chronic obstructive lung disease and acute respiratory failure. 86 35

The phenotype and antiquity of methanogenic bacteria suggest them to have been one of the major factors determining a dynamic balance between CO2 and CH4 in the primitive atmosphere.
J Mol Evol 1977 Aug 05
PMID:A comment on methanogenic bacteria and the primitive ecology. 89 39

1. Oxygen breath tests were performed in nine patients with diffuse pulmonary infiltration whose resting arterial PO2 (Pa, O2) ranged from 8-9 kPa to 11-8 kPa. The inspired air was suddenly replaced with oxygen for 30 s and the percentage fall in ventilation over the last 10 s was measured. 2. Pa,O2 rose rapidly and exceeded 16 kPa within 20 s in each patient. 3. The ventilation fell significantly in seven of the nine patients. It is concluded that these seven patients had a demonstrable reflex hypoxic respiratory drive at rest. This tended to be greatest in patients with the lowest Pa, O2. The percentage falls in ventilation observed were similar to those previously reported at comparable Pa, O2 levels in patients with chronic bronchitis. 4. The resting arterial PCO2 (Pa,CO2) ranged from 5-0 to 5-8 kPa. It did not change by more than 0-3 kPa during the oxygen breath tests in any patient.
Clin Sci Mol Med 1976 Feb
PMID:Estimation of the resting reflex hypoxic drive to respiration in patients with diffuse pulmonary infiltration. 94 73

1. Physiological dead-space volume (V D) was measured in twenty-four healthy men and women aged from 20 to 71 years, at rest and at two rates of work on a treadmill, whilst breathing air and breathing oxygen. 2. The effect of correction of arterial carbon dioxide tension (Pa,CO2) to pulmonary capillary temperature on the resulting value for V D was investigated. We find that the effect is substantial and that a correction should be made. 3. Equations have been derived for the prediction of normal V D during exercise. The best prediction was given by a regression on height, age, carbon dioxide output, ventilation and respiratory frequency, with an upper 95% confidence limit of +81 ml.
Clin Sci Mol Med 1976 Oct
PMID:Gas exchange during exercise in healthy people. I. The physiological dead-space volume. 97 73

The temperature dependence of various metabolic processes (glycolysis, fructolysis, glycogenolysis, ketogenesis, CO2-production, oxidative decarboxylation of pyruvate and gluconeogenesis) was studied in perfused rat livers. The processes measured differed with respect to their temperature dependence. Moreover, the sensitivity towards changes in temperature differed depending on the temperature range. Q10 values were found between 1,7 and 25 corresponding to values for activation energies between 38 and 216 kJoule/Mol.
 ...
PMID:[Temperature dependence of metabolic processes in perfused rat liver (author's transl)]. 98 15


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