bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aortic blood flow in dogs during treadmill exercise
Authors: Franklin Dean L. , Ellis Richard M. , Rushmer R. F. 
Published: December 2017

Instantaneous blood flow through the thoracic aorta was monitored continuously during spontaneous activity in intact dogs by means of a new, pulsed, ultrasonic flowmeter. Integrated flow per stroke, accumulated flow per unit time and heart rate were simultaneously derived by means of electronic computers. During treadmill exercise at 3 mph on a 5% grade, the heart rate increased by two- or threefold, but the aortic flow per stroke was only slightly increased. This observation was confirmed by direct measurements, of left ventricular diameter. An increase in stroke volume is not an essential feature of the cardiac response to exercise in these experiments. Submitted on December 15, 1958
Maximum oxygen intake and maximum heart rate during strenuous work
Authors: Wyndham C. H. , Strydom N. B. , Maritz J. S. , Morrison J. F. , Peter J. , Potgieter Z. U. 
Published: December 2017

At least five separate determinations were made of oxygen intake and heart rates at various levels of work on a bicycle ergometer, up to and above the maximum level of O2 intake of four highly trained men. From these measurements it has been possible to fit appropriate curves to the experimental data and test for their goodness of fit. At low rates of work a straight line fits both O2 intake and heart rate plots against work rate, but at high work rates the curves tend toward an asymptote. The O2 intake curve reaches its asymptote more slowly than does the heart rate; hence, if heart rate is plotted against O2 intake and a straight line fitted and extrapolated to the maximum value of heart rate, the O2 intake at this value is an underestimate of the actual measured maximum O2 intake. Because of the characteristic slope of the best-fit curve of oxygen intake against work rate, the criteria proposed by some earlier investigators for the level of O2 intake at which the maximum is unequivocally attained, is open to criticism. An alternative is proposed. The maximum levels of O2 intake and maximum heart rate of trained men studied over 4 months is remarkably constant, having average coefficients of variation of 4.3% and 3.5%, respectively. Submitted on December 2, 1958
Biologic assay of a thrombosis-inducing activity in human serum
Authors: Wessler Stanford , Reimer Stanley M. , Sheps Mindel C. 
Published: December 2017

The systemic infusion of thrombin-free human serum induces massive thrombosis in rabbit vein segments containing stagnant blood far removed from the site of infusion. In contrast, carefully collected human plasma is inert in this system. The data indicate that this phenomenon of in vivo thrombosis is quantitatively related to the amount of serum infused and forms the basis for a bioassay of the thrombosis-inducing activity. This bioassay, in providing a technique for detecting and quantitating the thrombosis-inducing activity of normal human serum, may facilitate separation of this activity from other recognized coagulation factors and serve as a guide to its ultimate isolation, purification and characterization. Note: (With the Technical Assistance of Marjorie Nickles, Mary-Lou Bloede, Bela J. Szalai and Rita J. Nickerson) Submitted on June 18, 1959
Mathematical analysis of the time course of alveolar CO2
Authors: Yamamoto William S. 
Published: December 2017

Continuous respiratory CO2 gas exchange is simulated theoretically by means of a suitably constructed dilution equation of the form (See PDF) where C is instantaneous concentration, Q quantity flow, and V volume flow. When such an equation is constrained in its numerical solutions to yield inflow-outflow equality for CO2 in the steady state, solutions for CO2 as a time series are found to differ according to whether the site of entry of CO2 is entirely by venous blood or is also by inspired CO2. In the case of entry via the venous blood, increasing CO2 is eliminated while keeping mean CO2 constant with increasing fluctuations about this mean. In the case of entry via the lung, increasing CO2 is eliminated by raising the mean and at the same time oscillations diminish. Submitted on August 13, 1959
Regulation of human plasma fluoride concentration
Authors: Singer Leon , Armstrong W. D. 
Published: December 2017

There is a constancy of plasma fluoride content of individuals who use communal water within the range 0.15– 2.5 ppm fluoride. With an intake of 5.4 ppm of fluoride in the communal water there is a slight but significant elevation of the plasma concentration. There is no evidence of a marked or prolonged rise of plasma fluoride content following the ingestion of 1.0 mg fluoride or of a diurnal variation of plasma fluoride content. The mean plasma fluoride concentration of hospitalized patients is not different from that of normal people. The factors relating skeletal fluoride content to small and short-term rises of plasma fluoride concentration are discussed. Submitted on November 19, 1959
Augmentor action of the sympathetic cardiac nerves in man
Authors: Randall Walter C. , McNally Howard 
Published: December 2017

During surgical procedures involving the upper thoracic sympathetic trunk in man, systolic and diastolic pressures were recorded during electrical stimulation. Significant and frequently profound elevation in systolic pressure, with little change in diastolic pressure, resulted in a marked increase in pulse pressure which has been designated as an augmentor response. Cardiac acceleration was an accompanying but less impressive response. The upper four or five thoracic segments mediate both the chronotropic and the inotropic action of the sympathetics but the T1 to T3 levels are the most significant. Corollary observations in animal experiments indicate the response is related to increased force of myocardial contraction with consequent increased systolic ejection. Submitted on February 1, 1960
Heat production from shivering
Authors: Iampietro P. F. , Vaughan J. A. , Goldman R. F. , Kreider M. B. , Masucci F. , Bass David E. 
Published: December 2017

Healthy young men were exposed, nearly nude, for 2 hours or less to various environmental conditions (dry-bulb temperature, 90°–20°F; windspeed, μ1, 5, 10 mph). Oxygen consumption was recorded at intervals during exposure. The results show that even under conditions where no visible shivering was observed, there was an increase in heat production. Exposure to very low temperatures (20°F) with low winds did not evoke the largest increases in heat production. The greatest mean heat production (370 Cal/hr.) was associated with the highest windspeed (10 mph), and this value approached the maximum heat production which can be attained by shivering (mean value about 425 Cal/hr.). Thus, increasing the windspeed had a relatively greater impact on heat production than decreasing the dry-bulb temperature. The relationships between heat production and windspeed and heat production and dry-bulb temperature were nonlinear. Submitted on February 8, 1960
Estimation of body surface area of extremely obese human subjects
Authors: Tucker Garrett R. , Alexander James K. 
Published: December 2017

The body surface areas of one normal and four extremely obese human subjects have been estimated by three methods: a) direct measurement by a method similar to that which Du Bois described; b) calculation from the Du Bois height-weight formula; and c) calculation from the Du Bois linear formula. The values for the total body surface area of the obese subjects calculated from the height-weight formula varied up to 11% below those that were directly measured. The values for the total body surface area obtained with the linear formula ranged between 13% and 20% above the direct measurements, this being almost entirely due to discrepancies in the trunk and in the thigh estimations. It has been concluded that estimation of the body surface area oxf extremely obese subjects by the Du Bois height-weight formula is satisfactory when considered in relation to the accuracy of the physiologic measurements with which it is generally used. Because of the unusual body form the Du Bois linear formula has been found unsatisfactory for this group. Submitted on March 1, 1960
Physiological comparison of three types of ergometry
Authors: Bobbert A. C. 
Published: December 2017

A physiological comparison of cycling, cranking and walking has been made, using in all experiments the same subjects and methods. In cycling and cranking energy expenditure increases with work load in a rectilinear way, the energy expenditures being always higher in cranking. In treadmill walking energy expenditure per kilogram of body weight rises curvilinearly both with increasing speed and grade. In cycling, cranking and walking there are nearly the same relations between heart rate and metabolism. Ventilation in cranking always exceeds that in walking and cycling at the same level of oxygen consumption. The curve of ventilation versus oxygen consumption shows a steeper rise in cranking. In level and grade walking ventilation increases curvilinearly with oxygen consumption. Submitted on September 17, 1959
Ventilation and circulation after fluid aspiration
Authors: Halmagyi Denis F. J. , Colebatch H. J. H. 
Published: December 2017

Ventilated volumes, arterial oxygen content and carbon dioxide tension, cardiac output, ‘effective’ pulmonary capillary flow, systemic arterial, pulmonary arterial and pulmonary arterial wedge pressures were determined before and after the intratracheal administration of 1–3 ml/kg body weight of fresh and sea water in 23 intact and 14 vagotomized sheep in light thiopentone anesthesia. Five untreated animals served as controls. A precipitous fall and a prolonged depression of arterial oxygen saturation was observed, largely independent of the amount of fluid inhaled. Hypoxemia was due to a gross increase in venous admixture resulting from the perfusion of large unventilated portions of the lungs. Fluid aspiration was also followed by a significant degree of pulmonary hypertension caused by arteriolar constriction in the lungs. Pulmonary hypertension was found to be unrelated to hypoxia. Submitted on October 15, 1959
Some effects of breathing oxygen before and after exercise
Authors: Elbel Edwin R. , Ormond Donald , Close Donald 
Published: December 2017

Athletes in better than average physical condition breathed 100% O2 during 6 minutes of rest, air during 5 minutes of treadmill running at 8 m.p.h. and O2 during 19 minutes of recovery. The results were compared with a control procedure in which the same subjects breathed air throughout. It was found that the experimental procedure: a) did not significantly facilitate recovery as based upon payment of O2 debt, measured by a closed-circuit spirometric method; b) depressed the pulse rate during the first 2 minutes of exercise and during the recovery period; c) caused the respiratory rate to increase at rest, to decrease during the initial part of the recovery period, and to increase during the latter part of the recovery period; d) increased the percentage of O2 saturation of blood hemoglobin, as measured by an ear oximeter, during rest and recovery. Lower oximeter readings were found during the latter part of the exercise period. Submitted on July 26, 1960
Anatomic distribution of induced changes in blood volume, evaluated by regional weighing
Authors: Fell Colin , Rushmer Robert F. 
Published: December 2017

Anesthetized cats were supported on electronic scales placed under the head, thorax, abdomen and hindquarters, and the changes in the weights supported by these scales were recorded while blood was withdrawn and while blood and saline were infused. The recorded changes in weight indicated that the abdomen and the thorax both contributed significantly to the volume of withdrawn blood and that infused fluids were taken up by both regions. The blood volume of neither region was conserved at the expense of the other. The average weight change of the hindquarters was 5–10% of the over-all response, but in many cases the weight of the hindquarters was stable during an experiment. The average error in measurement of changes in total body weight was 6%. Interactions between the scales were evaluated by injecting mercury into pouches placed at specific anatomic locations. Interactions did occur, but were not so great as to invalidate the method. Submitted on September 16, 1960
Potassium distribution and toxicity in hypothermia
Authors: Hoff Hebbel E. , Deavers Stephanie , Huggins Russell A. 
Published: December 2017

Ten dogs were anesthetized with a combination of morphine and pentobarbital. Control arterial samples for serum potassium determinations were taken, and the animals were cooled to a mean rectal temperature of 27.9°C. At this point, a slow infusion of potassium chloride was started and was continued until the disappearance of the P wave on the continuously recorded electrocardiogram. Thirty minutes were allowed for equilibration. The apparent volume of distribution of potassium in these animals averaged 73% of the body weight. These values compared closely with values of 67% for normothermic animals receiving the same anesthetics and the same total amounts of potassium, but are lower than in similar animals given larger doses of potassium. Hypothermia lowered the lethal concentration of potassium in the serum to 8.9 mEq/l. Submitted on December 9, 1960
Cardiac output in normal resting man
Authors: Reeves John T. , Grover Robert F. , Filley Giles F. , Blount S. Gilbert 
Published: December 2017

Sixty-three measurements of cardiac output in 50 normal resting individuals utilizing pulmonary arterial catheterization and the classical Fick method were made to investigate the normal standards of cardiac output under these conditions. Variation between individuals in age, sex, body size and metabolic rate was great enough to render the cardiac index (cardiac output/ unit of body surface area) a rather insensitive standard of normal blood flow. Rather the variation was substantially improved by considering cardiac output to be linearly related to oxygen uptake. This direct relationship appeared to be the result of the A-V oxygen difference varying independently of oxygen uptake, metabolic rate and body surface area. The mean A-V oxygen difference was 39.8 cc/l. with one standard deviation of α5.8 cc/l. Submitted on August 8, 1960
Circulatory changes in man during mild supine exercise
Authors: Reeves John T. , Grover Robert F. , Filley Giles F. , Blount S. Gilbert 
Published: December 2017

Cardiac output and femoral A-V oxygen difference were measured in each of seven normal men at rest and during several stints of supine exercise to investigate the mechanisms of oxygen transport for stepwise increments of oxygen uptake. The femoral A-V oxygen difference increased sharply for mild exercise and showed smaller further increase for heavier exercise stints. The pulmonary A-V oxygen difference followed a similar behavior where the changes were of smaller magnitude. For mild exercise, increasing oxygen transport apparently depends to a greater extent on increasing femoral tissue oxygen extraction and to a lesser extent on increased femoral and total blood flow. For heavier exertion, increasing oxygen transport depends to a greater extent on increasing flow and to a smaller extent on a widening tissue oxygen extraction. Mechanisms which are utilized to meet the increased metabolic demands of exercise depend in part upon the severity of the exertion. Cardiac output appears not to be a simple linear function of oxygen uptake for various metabolic demands ranging from rest to heavy exercise. Submitted on August 8, 1960
Cardiac output response to standing and treadmill walking
Authors: Reeves John T. , Grover Robert F. , Blount S. Gilbert , Filley Giles F. 
Published: December 2017

Cardiac output measurements during cardiac catheterization were obtained in normal subjects for several grades of treadmill exercise. Femoral venous blood was sampled and the A-V oxygen difference for the exercising leg obtained. Measurements of central and femoral A-V oxygen difference and total oxygen uptake were also obtained in normal subjects during supine rest and during standing. When subjects merely stood, the A-V oxygen difference for the leg increased (whether the leg bore weight or not) much more than did that for the whole body. During treadmill walking femoral A-V oxygen difference was usually no greater than that during standing. Cardiac output was smaller and total body A-V oxygen difference was greater for treadmill walking than for supine bicycle exercise in which comparable levels of oxygen uptake were achieved. It is clear that change in posture alters the cardiac output response to exercise. An important aspect of the altered response was a marked difference in the circulation within the leg for these two postures both at rest and during exercise. Submitted on August 8, 1960
Variations of ventilation and diffusing capacity to perfusion determining the alveolar-arterial O2 difference: theory
Authors: Piiper Johannes 
Published: December 2017

The factors determining the alveolar-arterial O2 pressure difference, AaD, have been theoretically reinvestigated, taking into account the effect of unequal distribution of pulmonary diffusing capacity, D, to pulmonary perfusion, Q. It is shown that, for a given inspired gas and a given mixed venous blood, the AaD is determined by two parameters, the ratios diffusing capacity :perfusion, D/Q, and alveolar ventilation :perfusion, Va/Q. Two characteristics of both of these ratios, the mean value and the variation, affect the AaD. Submitted on May 23, 1960
Velocity of O2 uptake by human red blood cells
Authors: Staub N. C. , Bishop J. M. , Forster R. E. 
Published: December 2017

We have determined the over-all association rate constant, k'c, for the uptake of oxygen by normal human erythrocytes from 0% to 97% initial hemoglobin saturation at pH 7.4 and 37óC. With a modified Hartridge-Roughton rapid-reaction apparatus, we used a small oxygen electrode to follow the oxygen uptake process rather than using the usual photocolorimetric analytical methods. The value of k'c averages 164 mm-1 sec.-1 at 0% initial saturation, rises slowly to over 300 at 50%, and then climbs rapidly to over 1500 at 95%. The theoretical explanation for the increase in k-c with rising initial oxyhemoglobin saturation is based on the increasing prominence of the fourth chemical association rate constant, k-4, in the intermediate compound theory of Adair. It is known that k-4 is several times larger than any of the other three k–s. Submitted on December 19, 1960
Body composition at sea level and high altitudes
Authors: PicÓn-Reátegui E. , Lozano Rodolfo , Valdivieso José 
Published: December 2017

Simultaneous determinations of total body water and extracellular fluid, using the antipyrine and sucrose infusion methods, have been carried out in 28 adult male residents at sea level and in 28 residents at an altitude of 14,900 ft. Body composition was calculated from these data. The various body spaces, expressed in percentage of body weight, were similar in the two groups, with the exception of the extracellular fluid which was greater in those in the high altitude group ( P < 0.01). Neither racial characteristics nor altitude appear to be factors generally affecting body composition. In individuals having adequate caloric intake body composition seems to be influenced principally by physical activity. In fact, physical inactivity appeared to produce a loss of active tissue and its replacement by fat. Submitted on November 2, 1960
Citric acid cycle in certain alterations of acid-base balance in human subjects
Authors: Gamble Wilbert , Orten James M. , Smith Arthur H. 
Published: December 2017

An accurate chromatographic (silica gel) procedure for the quantitative measurement of the stable citric acid cycle acids and certain noncycle acids in urine was developed. The identity of the isolated acids was verified by paper chromatography. The method was applied to a study of urinary excretion of the cycle and other acids during certain alterations in acid-base balance in eight normal subjects, and one diabetic patient. During a “basic” regimen, the “alkaline tide,” and “respiratory alkalosis,” a significant increase in the excretion of citric acid occurred, with no significant change in that of the other cycle and noncycle acids. The “acidic” regimen produced a uniform decrease in the excretion of citrate to values approaching statistical significance; there was no consistent alteration in the excretion of the other acids. A similar decrease in the excretion of citric acid was observed in the patient during diabetic acidosis. It is concluded that of the Krebs cycle and other acids studied, the urinary excretion of only citric acid varies with alterations in acid-base balance. Submitted on February 10, 1961
Dilution of alveolar gases during nitrous oxide excretion in man
Authors: Rackow Herbert , Salanitre Ernest , Frumin M. Jack 
Published: December 2017

The effect of N2O excretion upon O2 and CO2 levels in man was studied during two different types of artificial respiration with air. When a constant inflating pressure type respirator was used, the average fall in end-tidal Pco2 was 2 mm Hg or 5%. The measured fall in alveolar Po2 could not be determined with confidence, although theoretical considerations indicate it to be greater than 5%. When the respirator was servo controlled by end-tidal CO2 in a manner closely analogous to the human central respiratory mechanism, with the Pco2 level thus held constant, the inflating pressure fell and the average arterial O2 saturation fell 2.8% (20 mm Hg, or a 21% fall). These results have been interpreted to reflect the influence of N2O excretion upon both alveolar O2 and CO2. Submitted on February 6, 1961
Diffusion and solubility factors in pulmonary inert gas exchanges
Authors: Chinard Francis P. , Enns Theodore , Nolan Mary F. 
Published: December 2017

Comparisons have been made in anesthetized dogs of the relative recoveries in arterial blood of pairs of inert gases injected as solutions into the right heart or as gas mixtures into the trachea. The gases differed in their diffusion coefficients or in their solubility. The pairs used were: tritium and Kr85; ethylene-C14 and Xe133. The ratios of the recoveries of the gases approached the ratios of their solubilities and not the ratios of their diffusion coefficients. The site of injection had no significant effect. The concentration-time curves remain proportional during the first passage through the lungs. Diffusion equilibrium is attained within the time of passage of blood through the alveolar capillary. There is no evidence of a diffusion limitation on the exchange of gases with diffusion coefficients as small as that of xenon. Solubility is the limiting factor. Submitted on April 12, 1961