bluuebunny/crossref_metadata_2025_split huggingface dataset:
Square-wave electromagnetic flowmeter employing commercially available recorder
Authors: Scher Allen M. , Zepeda Julian , Brown Otis F. 
Published: December 2017

The availability of a stable, highly sensitive commercial recorder led us to construct a simple delay unit and square-wave driver for the purpose of measuring blood flow electromagnetically. The construction of the flowmeter heads is described briefly, and some analysis is made of possible deficiencies in flowmeter heads employing iron cores. The flow-measuring system is sensitive and linear and, when the magnet drive is turned off, the base line is within a few microvolts of true zero flow. blood flow in intact animals; epoxyresin embedding implantation Submitted on March 4, 1963
Indocyanine green densitometry in flowing blood compensated for background dye
Authors: Edwards Anthony W. T. , Isaacson James , Sutterer William F. , Bassingthwaighte James B. , Wood Earl H. 
Published: December 2017

Blood is nonhomogeneous; hence, the relationship between light transmission and increasing concentration of dye in whole blood is never the perfect exponential curve predicted by Beer's law. Instead, as the concentration of indocyanine green is increased to high levels (40 mg/liter) the light transmission decreases exponentially toward an asymptote at 6–8% transmission for nearly monochromatic densitometers (half-band width: 13–20 mμ), but at 30–40% for densitometers using light of wide-band width. Consequently, following recording of a dilution curve, circulating background dye reduces the change in transmission per unit increase in dye concentration in subsequent curves. This decrease in sensitivity cannot be compensated for by a simple increase in the sensitivity of the densitometer or in the intensity of its light source. Compensation can be attained, however, if increasing densitometer sensitivity is associated with the automatic scale expansion provided when a suppressed zero point is used. At correct zero suppression, the deflection for zero output of the densitometer coincides with the asymptotic transmission value mentioned above. indicator-dilution in circulation; blood flow measurement; blood optical density; dye dilution technic; cardiac output measurement Submitted on April 15, 1963
Effects of carbon dioxide inhalation on sweating
Authors: Bullard Robert W. 
Published: December 2017

Inhalation of 6% carbon dioxide by male subjects exposed to three different ambient temperatures resulted in increased sweating as measured by resistance hygrometry. The increase, which occurred in all body areas studied, reached approximately 100% over the control levels. All measured body temperatures decreased during or immediately following the carbon dioxide period. In the recovery period a marked depression of sweating occurred which ended as skin temperatures increased. body temperature; thermal effector activity (cyclic sweat gland activity); skin temperature; tympanic membrane and hypothalamus temperatures; resistance hygrometry responses to heat Submitted on April 24, 1963
Prolonged exposure of young rats to an oxygen atmosphere at reduced pressure
Authors: Dines John H. , Hiatt Edwin P. 
Published: December 2017

The effect was studied of exposing 12 young male white rats to an atmosphere almost free of nitrogen but with an alveolar Po2 the same as that of the 12 control animals breathing ambient air. This was achieved by keeping the experimental animals in almost pure oxygen at a reduced pressure. Experimental and control animals were in closed chambers with oxygen being supplied from a spirometer while Co2 was absorbed. Humidity and temperature were closely regulated. Provision was made for handling the animals and supplying them with food and water without changing the chamber environment. A successful experiment lasting 24 days was completed, not including observation periods of 6 days be-before and 8 days after the experiment when both groups were kept in air. No consistent difference was noted in rate of growth, oxygen consumption, food consumption, water intake, hemoglobin concentration, or behavior of the two groups. A decreased rate of urine production by the rats in the experimental group was attributed to an increased evaporative loss of water in the rarified atmosphere. nitrogen-free atmosphere; growth rate; O2 consumption; reduced pressure; oxygen low pressure atmosphere Submitted on March 20, 1963
Aerobic and anaerobic metabolism in exercising dogs
Authors: Cerretelli P. , Piiper J. , Mangili F. , Ricci B. 
Published: December 2017

For an analysis of the energy expenditure as related to the work performance in exercising dogs, the O2 consumption and the lactic acid production were determined at rest and during running on a treadmill at varying speeds (from 4 to 16 km/hr) and inclines (from 0 to +20%). The incline being constant, the O2 consumption was found to increase linearly with the speed. Although the maximum O2 intake probably could not be reached, the highest value measured, 100 ml O2/kg min, was about twice the average maximum O2 intake value for untrained men. The lactic acid production became detectable as the metabolic rate reached about 280 cal/kg min and increased at higher metabolic levels. The contribution of the anaerobic metabolism to the increase of the total metabolic rate due to exercise attained about 5% at the highest metabolic rate that could be measured, 580 cal/kg min The energy cost of running per kilogram body weight was found to be the same as in man for running on the level, 1.0 kcal/kg min; it increased more than in man in uphill running. The efficiency of running, as for man, was found to be independent of the speed. O2 consumption during running; lactic acid production during running; pyruvic acid production during running; energy cost and mechanical efficiency Submitted on July 15, 1963
An analysis of pressure-volume characteristics of the lungs
Authors: Salazar Eduardo , Knowles John H. 
Published: December 2017

By analysis of the retractive forces of the lungs it was found that the pressure-volume characteristics of the lungs may be expressed by an exponential function. The curve described by such expression could be fitted to the experimental data obtained in 20 normal subjects. A half-inflation pressure (h) was defined which makes possible the evaluation of the retractive forces of the lungs by a measurement independent of lung size and accounting for known curvilinearity. H is a useful index of the stiffness of the organ and it is defined as the increase in transpulmonary pressure necessary to inflate the lungs halfway to the maximal pulmonary volume from any resting level. The mean value of h for the group was 7.58 ± 2.53 cm H2O. The half-inflation pressure is independent of the level of measurement within the inspiratory capacity and it does not vary with or depend on the size of the lungs. It may therefore be a more useful expression of the retractive forces of the lungs than compliance. pulmonary retractive forces; lung stiffness; compliance half-inflation pressure and lung size; VC and half-inflation pressure; FRC and half-inflation pressure; new expression for compliance; pressure-volume curve Submitted on March 4, 1963
Effects of aspartic acid salts (Mg and K) on physical performance of men
Authors: Consolazio C. Frank , Nelson Richard A. , Matoush Le Roy O. , Isaac Gerhard J. 
Published: December 2017

The performance of twelve men was measured during a 9-week study. Six of the men received placebos and six received 2 g of magnesium and potassium salts of aspartic acid (Spartase) daily during 5 weeks of therapy. There was no significant difference in metabolic rate and RQ between the control or aspartate supplemented groups during moderate exercise and the recovery period after moderate exercise. Differences in other factors, such as maximum breathing capacity, vital capacity, breath-holding time, etc., were also nonsignificant. A few significant differences appeared between groups for the neuromuscular excitability values, which because of their erratic pattern probably were due to chance. Under the stresses imposed in this study there seemed to be no convincing evidence of the beneficial effects of aspartate therapy. exercise; neuromuscular fatigue; metabolic rate, respiratory measurements and physical fitness index under aspartate therapy; ergogenic drugs Submitted on May 8, 1963
Determinants of duration of left ventricular ejection in normal young men
Authors: Jones William B. , Foster Glenn L. 
Published: December 2017

The factors governing the duration of ejection were studied by statistical techniques at rest and during exercise in man. Data consist of 207 points in 20 subjects. Linear stepwise regression analysis results in the following formula for the prediction of the duration of ejection from the heart rate, stroke index, and the aortic diastolic pressure: duration of ejection = .36646 - .00108 (rate) - .00036 (diastolic pressure) + .00076 (stroke index). The correlation coefficient is 0.90 on comparison with the measured duration of ejection. The error of estimate is .0155 sec. The validity of the three variables was confirmed by factor analysis. Heart rate was found to be the major determinant of the duration of ejection. Stroke index and pressure have a relatively minor but statistically significant effect. ventricular ejection time prediction and calculation; factor analysis of ventricular ejection; cardiac output during exercise; heart rate, stroke index, and ventricular ejection; aortic diastolic pressure and ventricular ejection Submitted on July 18, 1963
Measurement of total pressure of dissolved gas in mammalian tissue in vivo
Authors: Lategola Michael T. 
Published: December 2017

An in vivo method for the quantitative estimation of total gas pressure in mammalian tissue has been established. This method utilizes a rigid-walled capsule specially constructed to be permeable to O2, CO2, and N2, but negligibly permeable to water vapor. The results obtained, after subcutaneous implantation of this capsule, directly demonstrate that the total gas pressure in the adjacent tissue interface is about 40–50 mm Hg less than the concomitant atmospheric pressure. This pressure difference is a result of the metabolic gas exchange of the tissue interface. tissue metabolism; blood-gas tensions; tissue-blood gas diffusion; gas-bubble physiology; dog tissues total gas pressure Submitted on July 25, 1963
In situ pressure-radius-length measurements in ascending aorta of anesthetized dogs
Authors: Patel Dali J. , Fry Donald L. 
Published: December 2017

Instantaneous pressure-radius-length relationship was studied in the ascending aorta of ten living dogs. Results indicate: 1) longitudinal and circumferential strains in the ascending aorta are large as compared to other segments of the aorta, and 2) it is suggested that the intravascular pressure may not be the only radially distending stress since other forces due to contraction of the heart seem to play a role in this local area. Note:With the Technical Assistance of Joseph M. Pearce mechanical properties ascending aorta living dog; stress-strain relation ascending aorta living dog Submitted on September 27, 1963
Hemodynamic response of normal men to graded treadmill exercise
Authors: Tabakin Burton S. , Hanson John S. , Merriam Thornton W. , Caldwell Edgar J. 
Published: December 2017

The physiologic variables defining the circulatory and respiratory state in normal man have been measured in recumbency, standing at rest and during progressively severe grades of exercise approaching near-maximal levels. Indicator-dilution technique was used for determination of cardiac output with simultaneous radio-electrocardiographic recordings of heart rate. Direct intra-arterial pressure measurements were utilized for calculation of peripheral vascular resistance. Minute volume of ventilation, oxygen utilization, and carbon dioxide elimination were obtained from analysis of expired air collected at the time of each cardiac output determination. A peak mean workload of 1,501 kg-m/min was realized during the treadmill exercise. Increases in cardiac output over the range of exercise employed correlated well with indices of workload such as heart rate, oxygen utilization, and minute volume of ventilation. There was no correlation of stroke volume with these indices. It is concluded from examination of individual stroke-volume responses that a progressive increase in stroke volume is not a necessary or constant phenomenon in adapting to increasing workload. cardiac output in treadmill exercise; dye-dilution cardiac output determinations; arterial pressure during upright exercise; stroke-volume response to graded treadmill exercise; exercise response of cardiac output and stroke volume; peripheral vascular resistance response to position and exercise; treadmill exercise—effects on cardiac output, stroke volume, and oxygen uptake; minute ventilation, cardiac output, and stroke volume during exercise; carbon dioxide elimination during treadmill exercise; heart rate and cardiac output during treadmill exercise; exercise; physiology Submitted on July 12, 1963
Reliability of estimation of metabolic levels from respiratory frequency
Authors: Ramanathan N. L. 
Published: December 2017

The reliability of estimating the physiological energy cost from the respiratory frequency has been tested from 114 exercise experiments on 11 volunteers. A correlation according to E (kcal/min) = -3.06 + 0.198 R (no/min) was obtained between energy consumption and breathing rate. This regression was highly significant (P < 0.01) with a correlation constant of 0.93 and standard error of only 0.46 kcal/min. The convenience of the method in comparison with pulse rate and pulmonary ventilation methods which have similar correlation and accuracy, have been discussed. In states of low energy metabolism and also in the performance of severe muscular tasks, when oxygen debt may occur, the present relation may not strictly apply. Breath amplitude also affects energy levels, but it seems to bear no relation to the effect of respiratory frequency. Techniques for observing respiratory frequencies accurately and for deriving the best estimate of energy cost under field conditions are described. Determinations of energy consumption to the first approximation are readily achieved by this method. exercise; respiratory rate and energy expenditure in man pulmonary ventilation and respiratory rate; work output measurement Submitted on May 21, 1963
Calibration of an impedance pneumograph
Authors: Kubicek W. G. , Kinnen E. , Edin A. 
Published: December 2017

An experimental calibration of an electrical impedance pneumograph is presented over a range of tidal volumes from 250 to 4,000 ml. Transthoracic impedance measurements were made on four subjects using 1-in. cup electrodes, and at a frequency of 100 kc/sec. A 1-ohm change of impedance magnitude corresponding to an average tidal volume of 830 ml was observed, based on a total of 1,063 measurements. The standard deviation of these data was approximately 50% for low tidal volumes and 30% for the larger tidal volumes. Data from individual subject trials indicated significant variations in the calibration constants and regions of apparent linearity, both between subjects and between trials on each subject. Experimental records of the change in impedance magnitude as a function of inspired air volume during inspiration are included to illustrate typical variations. plethysmography, impedance; impedance, transthoracic; tidal volume, measurement of; respiration meter Submitted on July 29, 1963
Base-line effects on response of stroke volume to leg exercise in the supine position
Authors: Frick M. H. , Somer Timo 
Published: December 2017

Cardiac output was measured with dye dilution in normal subjects at rest in horizontal position, at rest supine with the legs on the pedals, and during increasing work loads. Experiments were designed to clarify the effect of leg raising on comparisons of stroke volume at various levels of exercise. Leg raising evoked a 19% increase in stroke volume and a decrease in heart rate. Oxygen uptake and A-V O2 difference remained unaltered. In comparing stroke volume at mild exercise with leg-raised resting position, no change occurred contrasting the significant rise when compared with horizontal position. At mild exercise cardiac output response was relatively flat, whereas A-V O2 difference rose sharply. At heavier exercise cardiac output rose more steeply and approximately linear to oxygen consumed. Stroke volumes at these loads were significantly higher than levels in both of the resting positions. Ignorance of the effect of leg raising results in misinterpretation of the stroke volume data at low levels of supine exercise when greatly enhanced tissue extraction of oxygen allows smaller blood flow increments. base line in exercise; exercise stroke volume; stroke volume, exercise; stroke volume, base line; supine exercise Submitted on December 13, 1963
Effect of exercise on zonal distribution of pulmonary blood flow
Authors: Read John , Fowler K. T. 
Published: December 2017

Redistribution of pulmonary blood flow was studied by means of the cardiogenic oscillations of expired gas tensions in seven normal subjects during exercise in the vertical posture. The results are expressed in terms of Qr, the ratio of blood flow per unit of alveolar volume between upper and lower zones of the lungs, and are compared with the response of the same subjects to alveolar hypoxia. In six subjects, Qr rose on exercise by an amount which varied from subject to subject and from day to day, depending on the resting level of Qr. A further subject usually failed to increase Qr on exercise. Aminophylline reduced resting Qr in some subjects. It is concluded that the response of Qr to exercise depends on the extent to which active pulmonary vasodilatation occurs. Differences in the response of Qr to exercise, hypoxia, and aminophylline are interpreted in terms of differing initial pulmonary vasomotor tone. gas tension; argon; alveolar volume; alveolar hypoxia Submitted on August 5, 1963
Effect of surface tension on circulation in the excised lungs of dogs
Authors: Bruderman I. , Somers K. , Hamilton W. K. , Tooley W. H. , Butler J. 
Published: December 2017

The hypothesis that the surface tension of the fluid film which lines the lung alveoli reduces the pericapillary pressure in air-filled lungs was tested by perfusing the excised lungs of dogs with saline, 6% dextran in saline, and blood. After almost maximal inflation with air from low volumes or the degassed state (inflation state) the pulmonary arterial pressure, relative to the base of the lungs, was lower than the alveolar pressure with flows up to 50 ml/min. It was higher than the alveolar pressure at any flow when the air-liquid interface had been abolished by filling the lungs to the same volume with fluid. The pulmonary arterial pressure at the same flow and alveolar pressure was lower in the inflation state than after deflation from higher volumes (the deflation state). However, lung volume was larger in the deflation state. The possibility of some low resistance channels in the inflation state could not be excluded. However, histological examinations showed that the alveolar capillaries were patent and failed to show any airless lung. pulmonary circulation; pericapillary pressure in lungs; surface tension and pulmonary vascular resistance Submitted on July 29, 1963
Lung volume, compliance, and arterial oxygen tensions during controlled ventilation
Authors: Laver Myron B. , Morgan John , Bendixen Henrik H. , Radford Edward P. 
Published: December 2017

The relationship between total dynamic compliance (lung plus chest wall), functional residual capacity, and alveolar-arterial oxygen gradients (A-a DO2) was studied in paralyzed dogs during constant-volume ventilation with pure oxygen. Rapid changes in functional residual capacity (FRC), produced by forced deflation of the lungs, were associated with a rapid fall in total compliance and rise in A-a DO2. Subsequent hyperinflations (deep breaths) restored compliance to control levels more readily than A-a DO2. Changes in the FRC, measured with a whole-body plethysmograph, were related directly to total compliance and inversely to A-a DO2. Collapse of the terminal regions of the lungs produced by forced deflations was associated with a decrease in total compliance of 36%, and a decrease in FRC of 26% with a simultenaous rise in A-a DO2 to a mean of 547 mm Hg. It is concluded that intermittent deep breaths administered during constant-volume ventilation will not necessarily restore control levels of compliance and A-a DO2 equally well. This difference is probably dependent on altered alveolar surface characteristics or mechanics, or both, secondary to the collapse process, which prevent restoration of structural integrity by a deep breath. total dynamic compliance; functional residual capacity; alveolar-arterial oxygen tension difference; atelectasis; deep breath Submitted on October 31, 1963
Dream recall and the physiology of sleep
Authors: Shapiro Arthur , Goodenough Donald R. , Biederman Irving , Sleser Irving 
Published: December 2017

Thirteen subjects were studied for 4 nights of sleep by simultaneous recording of EEG, eye-movement potentials, heart rate, and respiration. The subjects were awakened from stage 1 sleep periods with rapid, conjugate eye movements (REM periods) and asked to describe any preawakening experiences (dream or thoughts). Respiratory rate was more irregular during REM periods which led to dream reports than during REM periods which led to reports of dreamless sleep. Submitted on August 5, 1963
Analysis of high concentrations of oxygen in the Scholander apparatus
Authors: Nelson Nicholas M. 
Published: December 2017

A method is presented for accurate analysis of large amounts of absorbable gases in the Scholander apparatus; the standard technique is altered only by mixing the unknown sample with a known amount of diluting gas. This modification significantly improves speed and accuracy in high oxygen analyses; reproducibility of ±.04% is easily obtainable in gas samples containing over 95% oxygen. high oxygen; accurate Scholander analysis Submitted on February 24, 1964
Circulatory response to prolonged severe exercise
Authors: Saltin Bengt , Stenberg Jesper 
Published: December 2017

Four subjects worked on a treadmill or a bicycle ergometer for 180 min at oxygen uptakes of 75% of the individual's max Vo2; after 90 min rest, the exercise was resumed and a maximal work load was tried. Repeated circulatory studies were made. The body weight decreased 3.1 kg (3.2–5.2%), but the reduction in blood volume was less than 5%. During submaximal exercise the major change in the hemodynamic response was a decrease in stroke volume (from 126 to 107 ml). Oxygen uptake and cardiac output increased slightly. There was a decrease of about 10% in systolic, diastolic, and mean arterial blood pressure during the 180 min of exercise. When the work was performed in a supine position there was the same reduction in the stroke volume as in the sitting work position. At the maximal work oxygen uptake, cardiac output, heart rate, and blood pressure attained almost normal values but there was a marked decrease in both work time and blood lactates. dehydration; blood volume; arterial blood pressure; circulatory reaction Submitted on January 31, 1964