bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of upper and lower airway resistance and conductance in man
Authors: Blide Richard W. , Kerr H. David , Spicer William S. 
Published: December 2017

The resistances to flow in the upper (Ruaw) and lower (Rlaw) airway of human lungs were measured simultaneously with total airway resistance (Raw) and the volume of thoracic gas (Vtg) using the plethysmographic method and lateral pressure taps at the tracheal and oral levels. Ruaw is found to decrease slightly in a curvilinear fashion with increasing Vtg while its reciprocal, Guaw, is linearly related to Vtg with a negative Vtg intercept in normal subjects. Lower airway conductance (Glaw) is linearly related to Vtg with a slope of approximately 1.0 liters/sec per cm H2O per liter. From the partitioned resistances it is deduced that total airway conductance (Gaw) is curvilinear but approximately linear over the majority of the Vtg. A method of calculating resistance and conductance in the upper and lower airways from Raw versus Vtg data is presented using the equation Raw = Vtg/(A @#X002B; B Vtg) where B2/A @#X003D; dGlaw/ dVtg. Three hundred and sixty-two records of Raw versus Vtg data from 22 normal, asthmatic, and bronchitic subjects are then evaluated by this method and the results compared to those obtained by direct measurement. intrathoracic or lower airway conductance; intrathoracic or lower airway resistance; extrathoracic or upper airway conductance; extrathoracic or upper airway resistance Submitted on November 8, 1963
Duct flow and mitral regurgitation during changes of oxygenation in newborn swine
Authors: Rowe R. D. , Sinclair J. D. , Kerr A. R. , Gage P. W. 
Published: December 2017

Mitral regurgitation and blood flow through the ductus arteriosus were quantitated during acute changes in oxygenation in 20 newborn swine studied under open-chest conditions during ventilation with 21, 100, or 10% oxygen. Mitral regurgitation and duct flow were estimated from the abnormally early deflections on dilution curves recorded from the left atrium, when compared with those from the aorta, following injection of indicator into the left ventricle. The induction of acute hypoxia resulted in highly significant increase of shunt through the patent ductus arteriosus (P @#X003d; 0.001). On reoxygenation this shunt diminished significantly (P @#X003d 0.01). These effects were present in animals up to 48 hr of age, although the younger animals sometimes had appreciable duct flow under normal conditions of oxygenation while older animals required longer periods of hypoxia to make duct flow evident. The findings support the evidence of previous studies that oxygenation has a marked effect on the patency of the ductus arteriosus. In the same conditions mitral regurgitation was always insignificant. ductus arteriosus flow; hypoxia Submitted on February 17, 1964
Measurement of left ventricular volume by thermodilution: an appraisal of technical errors
Authors: Rolett Ellis L. , Sherman Herbert , Gorlin Richard 
Published: December 2017

An analysis of the technical errors inherent in the determination of left ventricular volume by indicator-dilution methods, particularly thermodilution, is presented. Inaccuracies in the measurement of the true rate of indicator washout from the ventricle are related to valvular regurgitation, heat transfer between ventricular wall and chamber, and a long sensor time constant; variations occur due to heterogeneous indicator mixing in the chamber and at the transducer. It is shown that, whatever the reason for error, it multiplies as the fraction of ventricular emptying becomes smaller. The error is reduced through the use of a sensor with an appropriately short time constant and through the acquisition of multiple dilution curves and stroke volume measurements. An estimate of the relative error in the computed left ventricular volume is possible and only under optimal circumstances is close to that found in the determination of cardiac output. The remaining variation in computed volume is primarily an indication of variable indicator mixing. The conditions required for reliability are extensive and place restrictions on the general usefulness of the method. indicator-dilution technic; end-diastolic volume; residual volume; thermistor Submitted on October 29, 1963
Cerebral metabolism of doubly labeled glucose in humans in vivo
Authors: Sacks William 
Published: December 2017

With glucose-3-C14 as injected substrate, the production of C14O2 almost kept pace with the net uptake of C14 by brain. Brain C14O2 specific activities practically coincided with venous blood glucose specific activities. This rapid production of C14O2 with little or no dilution of C14 led to the derivation of theoretical curves for glucose-2-, glucose-1-, or glucose-6-C14 experiments. The dissimilarity between theoretical and experimental values suggested that there is a significant dilution of C14 in traversing the Krebs cycle. Equations derived from hypothetical metabolic pathways which included a pool of substrate, x, were employed to match theoretical with average experimental values. In experiments with doubly labeled glucose-C14-T, brain TOH (tritiated water) specific activities were used to derive brain C14O2 specific activity values which closely approximated actual results. A scheme for human cerebral metabolism of glucose in vivo, which includes a small, metabolically active pool of glutamate, ggr-aminobutyrate, and succinic semialdehyde, is proposed. brain glucose oxidation; in vivo brain metabolism; isotopic glucose metabolism; glucose-C14-T cerebral metabolism Submitted on February 3, 1964
Sweat suppression by forced breathing in man
Authors: Albert Roy E. 
Published: December 2017

Thermal sweating from the forehead was suppressed by forced air breathing in two normal male subjects. The decreased sweat rate was associated with symptoms of respiratory alkalosis. This sweat suppression was blocked by the introduction of excess carbon dioxide into the respired gas. sweating and hyperventilation; hyperventilation and sweating; respiratory alkalosis and sweating Submitted on February 7, 1964
Variation of plasma ketones and free fatty acids during acute cold exposure in man
Authors: Hanson Peter G. , Johnson Robert E. 
Published: December 2017

We have studied the magnitude of ketosis induced during acute cold exposure. Plasma and urinary ketone bodies and plasma free fatty acids (FFA) were followed in four healthy young men at rest during a 90-min period of seminude exposure to 0 C in still air. This period was followed by 4 hr of recovery at 25 C. Each subject served as his own control throughout an experimental sequence in which one cold-exposure and corresponding control period (25 C) were experienced each week for 3 successive weeks. The subjects were in a fasting state but with water ad libitum beginning 12 hr prior to the experiment. Light weight clothing was worn during recovery and control periods. The combined group data show a significant increase in plasma FFA during cold exposure as compared with similar control periods. Although true hyperketonemia or hyperketonuria did not develop, the levels of plasma ketones are elevated in the cold-exposure period of the first week. During the second and third week there is no difference between the cold and control plasma ketone concentration. The data suggest that FFA is mobilized as a metabolic substrate during cold exposure and that efficient peripheral utilization of the elevated plasma FFA concentration minimizes hyperketogenesis. ketone bodies; metabolism; nonesterified fatty acids Submitted on April 27, 1964
Agreement of cardiac outputs calculated from paired indicator-dilution curves
Authors: Opdyke David F. 
Published: December 2017

Cardiac outputs calculated from paired dye-dilution curves obtained by sampling simultaneously from two sites in the pulmonary arteries were compared. Similar comparisons were made between paired cardiac outputs derived from pulmonary artery and left atrial dye-dilution curves, from pulmonary artery and descending aorta curves, and from two sites in the descending aorta. Paired cardiac outputs derived from two sampling sites in the pulmonary arteries agreed better than paired estimates derived from the pulmonary artery and either left atrium or descending aorta. Poorest agreement was found when paired outputs derived from the pulmonary artery and descending aorta were compared. Paired outputs from two sites in the descending aorta agreed somewhat better than comparable pairs from pulmonary artery and either left atrium or descending aorta. Note: (With the Technical Assistance of John McMorrow, Bruce Brundage, Albert Gosen, and Rose Apostolico) agreement of paired cardiac outputs; cardiac output; output calculated from paired dye curves Submitted on February 17, 1964
Effect of lipemia and heparin on arterial carbon dioxide tension
Authors: Barboriak Joseph J. , Kory Ross C. , Hamilton Lyle H. , Helman Sandy I. 
Published: December 2017

Intravenous injection of heparin to lipemic subjects was followed by a rapid rise in arterial Pco2, amounting to 4.7 mm Hg 15 min after the injection; the alveolar Pco2 did not seem to be affected. In fasting subjects the postheparin rise in arterial Pco2 was less pronounced. Subsequent studies showed that the observed Pco2 rise occurred in vitro in the drawn blood and was due to an accumulation of unesterified fatty acids, liberated by the heparin-induced lipoprotein lipase. respiratory gases; arterial blood gases; blood pH; a-A Pco2 gradient; lipoprotein lipase Submitted on June 18, 1964
Safe exposure of men to severe heat
Authors: Bell C. R. , Hellon R. F. , Hiorns R. W. , Nicol P. B. , Provins K. A. 
Published: December 2017

Eight men were exposed to hot environments which ranged from 37 C/30 C to 63 C/47 C dry- and wet-bulb temperatures. They remained in the heat until they showed signs of distress just before collapsing. The time taken to reach this state was found to be hyperbolically related to the severity of the environment when this was expressed as a weighted sum of wet- and dry-bulb temperatures. Separate hyperbolae were found for standing and working subjects. After the deduction of a suitable safety margin, the resulting curves and their equations make possible the prediction of safe exposure times for severe heat heat stress; heat collapse; heat tolerance Submitted on May 13, 1964
Isometric cross-transfer effects under conditions of central facilitation
Authors: Kroll Walter 
Published: December 2017

Fifteen male subjects were given 16 trials of isometric flexion under two test conditions for each limb. Condition 1 consisted of odd-numbered trials being separate unilateral and even-numbered trials simultaneous bilateral contractions. In condition 2, the first 11 trials were separate unilateral and the last 5 trials were simultaneous bilateral. There was no evidence of central facilitation effects due to simultaneous bilateral versus separate unilateral wrist flexion during fatigued or nonfatigued states or upon dominant or nondominant limbs. Analysis of variance revealed only the linear trend component was significant in fatigue curves accounting for all but a small percentage of the observed variation in strength in the four experimental conditions. cross education; proprioception Submitted on June 11, 1964
Effects of cold exposure and exercise in a wet, cold antarctic climate
Authors: Budd G. M. 
Published: December 2017

Six men were studied before and after 6 weeks of strenuous outdoor work and cold exposure—often in wet clothing—on Heard Island in the Antarctic. Physical fitness increased significantly, while subcutaneous fat and arterial blood pressure decreased significantly. The response of rectal temperature and shivering to a 2-hr period of whole-body cooling did not change significantly (although shivering tended to decrease), suggesting that the reduction in insulation caused by loss of fat was balanced by an increase in the insulation of other tissues. Finger temperature fell more rapidly, there was less cold vasodilatation, and the gradient of skin temperature between elbow and finger increased significantly, suggesting that heat was conserved by means of countercurrent heat exchanges and enhanced vasoconstriction. Discomfort from cold did not change. These results support those of a previous study at Mawson, Antarctica. Frostbite of one subject's hands, which grossly impaired touch sensation and caused marked intolerance to cold, produced no obvious changes in the response to cold of finger temperature. vasomotor adaptation to cold; cold vasodilatation; tissue insulation; subcutaneous fat; shivering; subjective responses to cold; frostbite sequelae; finger temperature before and after cold injury; physical fitness; acclimatization to cold Submitted on September 8, 1964
Aerobic work capacity in middle-aged Norwegian men
Authors: Andersen K. Lange , Hermansen Lars 
Published: December 2017

Maximal oxygen uptake and related respiratory and circulatory functions were measured in sedentary and well-trained middle-aged men. Maximal oxygen uptakes averaged 2.63 liter/min in sedentary men and 3.36 liter/min in well-trained men, the latter value being essentially the same as found in young untrained students. The heart rate/ oxygen uptake relationship was found to be the same for sedentary-living men, regardless of age, but maximal heart rate was lower in older men. The maximal heart rate is probably the same in well-trained as in sedentary middle-aged men, this in contrast to what has been observed in younger age groups, where training reduces maximal heart rate. The exercise-induced hyperventilation takes place at an oxygen uptake corresponding to 70–80% of the capacity, this being the same in trained and untrained, and essentially the same as found in young adult subjects. maximal O2 uptake Submitted on March 23, 1964
Increase in breathing frequency following the reflex deep breath in anesthetized cats
Authors: Reynolds Leslie B. , Hilgeson Mata D. 
Published: December 2017

In anesthetized cats, the inspiration-augmenting reflex, manifested as a spontaneous deep breath, was followed by a transient increase in breathing frequency in 66.5% of 382 cases observed. To determine whether this frequency increase was a property of altered mechanical properties of the lungs or was a property of the reflex itself, intact animals had their lungs inflated under conditions which would elicit the reflex as well as under conditions in which the reflex was absent. In all cases, dynamic lung compliance increased when the lungs were stretched. When the augmenting reflex was absent, breathing frequency decreased with increasing stretch. However, when the reflex occurred, breathing frequency increased to a maximum at a lung stretch of two and one-half times tidal volume. Frequency effects observed could be attributed to a combination of slowing by lung stretch and reflex speeding effects. The inspiration-augmenting reflex is proposed as a possible contributing mechanism to the tachypnea associated with lung conditions in which compliance is low. lung compliance; inspiration-augmenting reflex; breathing frequency changes; pulmonary airflow resistance; control of respiration; reflex tachypnea Submitted on May 18, 1964
Continuous recording of C14O2 excretion and O2 consumption by rats
Authors: Simpson-Morgan M. W. 
Published: December 2017

An apparatus is described with which the O2 consumption and C14O2 excretion of small laboratory animals can be recorded and integrated continuously during the course of experiments with C14-labeled compounds. In addition, the total CO2 production throughout intervals can be determined and the respiratory quotient calculated. The oxygen consumption apparatus is simple, inexpensive, and sensitive, and can be used in any closed metabolism system. apparatus; isotope; oxidative metabolism Submitted on July 10, 1964
Intertissue diffusion effect for inert fat-soluble gases
Authors: Perl William , Rackow Herbert , Salanitre Ernest , Wolf Gerald L. , Epstein Robert M. 
Published: December 2017

An approximately constant 5% difference in alveolar concentration of nitrous oxide and cyclopropane exists when these two gases are administered simultaneously to human subjects. This difference in uptake cannot be fully explained within the traditional framework of a perfusion-limited, multi-compartment model of inert gas exchange. It is proposed that this difference reflects direct diffusion from lean to neighboring adipose tissue through distances of the order of 1 mm. The diffusional rate of cyclopropane uptake into adipose tissue is initially large relative to perfusional uptake. The two rates eventually become and remain comparable as both decrease to zero. Implications of these results for deduction of blood flow to body adipose tissue by gas uptake measurement, and for utilization of capillary exchange surface by fat-soluble gases in adipose tissue are discussed. compartment model generalization; gas uptake in body; inert, fat-soluble gas uptake; kinetics of gas exchange in body; body uptake of inert gases; fat-soluble gas uptake; distribution kinetics of gases in body Submitted on February 3, 1964
Measurement of intrabronchial pressure in man
Authors: Macklem Peter T. , Wilson N. J. 
Published: December 2017

By measuring total and lateral airway pressures in intact normal man, simultaneously with esophageal pressure, volume, and flow, it was possible to estimate the pressure difference across the wall of the airway, the pressure-flow curves of various segments of the airway, and the compliance of the airway. The results showed that: 1 Expiratory airway compression only occurs between the segmental bronchi and the glottis at volumes between 75 and 25% VC. 2) Expiratory flow is limited by compression of these airways. 3) The resistance of airways between segmental bronchi and trachea is variable, being markedly affected both by lung volume and pleural pressure. Tracheal resistance varies little with lung volume, but considerably with pleural pressure. The resistance of the airways between alveoli and segmental bronchi varies with lung volume but little with pleural pressure. These are probably the major resistance airways during quiet breathing. 4) Airway compliance is inversely related to lung volume. 5) The Bernouilli effect is large in large airways and helps to limit expiratory flow. bronchial pressure; airway resistance; airway compliance; maximal expiratory flow; equal pressure point; lung mechanics; airway compression Submitted on November 5, 1964
Cardiopulmonary effects of continuous pressure breathing in hypothermic dogs
Authors: Salzano J. , Hall F. G. 
Published: December 2017

Continuous pressure breathing was studied in hypothermic anesthetized dogs. Alveolar ventilation decreased during continuous positive-pressure breathing and increased during continuous negative-pressure breathing. The changes in alveolar ventilation were due to changes in respiratory rate as well as in respiratory dead space. Cardiac output fell significantly during continuous positive-pressure breathing due to a reduction in heart rate and stroke volume. During continuous negative-pressure breathing cardiac output was only slightly greater than during control as a result of a fall in heart rate and an increase in stroke volume. Oxygen consumption was reduced to 60% of control during continuous positive-pressure breathing of 16 cm H2O but was 25% greater than control during continuous negative-pressure breathing. Qualitatively, CO2 production changed as did O2 consumption but was different quantitatively during continuous negative-pressure breathing indicating hyperventilation due to increased respiratory rate. Mean pulmonary artery pressures and pulmonary resistance varied directly with the applied intratracheal pressure. The results indicate that the hypothermic animal can tolerate an imposed stress such as continuous pressure breathing and can increase its oxygen consumption during continuous negative-pressure breathing as does the normothermic animal. hypothermia; respiratory dead space; metabolic rate; cardiac output Submitted on December 8, 1964
Effect of vertical vibration on respiratory airflow and transpulmonary pressure
Authors: Zechman Fred W. , Peck Davis , Luce Edward 
Published: December 2017

The response of the human thoracoabdominal system to whole-body, vertical, sinusoidal vibration has been studied. Peak acceleration of the shake table was held constant (±0.5 G), and frequency varied between 2 and 10 cycles/sec. Subjects were seated with trunk axes parallel with the direction of acceleration. The amplitude of forced airflow oscillation increased with frequency to an average 1,368 cm3/sec at 6 cycles/sec and then decreased. The maximum average volume of air forced in or out of the lung with vibration was 46 cm3 at 5 cycles/sec. Transpulmonary pressure fluctuation exhibited a peak average amplitude of 5.44 cm H2O at 5 cycles/sec. The response to square-wave table motion was also investigated. The transient flow oscillation produced by the step function had an average frequency of 5.6 cycles/sec. Measurements of the logarithmic decrement of transient flow oscillation indicate the total thoracoabdominal system is underdamped (hV = 0.1–0.2). The calculated damping for the lung subsystem indicates very high damping (hL = 4.5). Measurements of abdominal deformation produced by the step function suggest the transient flow oscillations result from close coupling of the lung to other components of the thoracoabdominal system. Note: (With the Technical Assistance of Tom Sharp, Roger Shannon, and Judith White) whole-body vibration; periodic vertical acceleration; vibration-induced changes in respiration; oscillation; mechanics of thoracoabdominal system Submitted on February 14, 1964
Effect of temperature on deoxygenation rate of human red cells
Authors: Lawson W. H. , Holland R. A. B. , Forster R. E. 
Published: December 2017

The rate of deoxygenation of oxygenated human red cell suspensions was measured in vitro as a function of temperature from 7 to 42 C at constant Pco2 in a stopped-flow rapid-reaction apparatus. There is a linear relationship between the deoxygenation rate constant, kc, and the reciprocal of the absolute temperature; the “activation energy” of 16,743 cal/mole agreed reasonably well with that predicted by theory, 14, 565. At 42 C deoxygenation was half complete in 0.04 sec while at 7 C the half-time was slowed to 0.8 sec. If the red cell transit time in tissues cooled to 7 C approximates the normally accepted value at 37 C of about 1 sec, the rate of red cell deoxygenation would be a limiting factor in the supply of oxygen to the peripheral tissues in the cold. capillary diffusion; respiration; stopped-flow rapid-reaction apparatus Submitted on May 14, 1964
Mixing of dye and blood in the canine aorta
Authors: Krovetz L. Jerome , Benson Robert W. 
Published: December 2017

Paired simultaneous arterial sampling curves from both femoral or iliac arteries of 10 dogs were obtained following injections of indicator in the superior vena cava (SVC), right atrium (RA), left ventricle (LV), aortic root (AR), and descending thoracic aorta (DA). Calculated paired cardiac outputs following injection into the SVC or RA showed an average difference of 5.8% (se 0.97). Injections into the LV were not significantly different in this regard, having an average difference of 6.3% (P < 0.85). Injections into the AR and DA showed progressive increases in the differences of the paired curves, averaging 9.9% and 23.1%, respectively. The degree of aortic mixing of blood and dye appears to be related to the distance available for such mixing. While this cannot be interpreted as evidence for the existence of laminar flow in arteries, the degree of any existing turbulence is inadequate for complete mixing. hemodynamics; turbulence; indicator-dilution theory; branching; arterial branches; cardiac outputs Submitted on October 2, 1964