bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiovascular response to oxygen inhalation in the anesthetized cat
Authors: Bevan John A. , Verity M. Anthony 
Published: December 2017

An analysis of the cardiovascular response to short periods of inhalation of O2 is presented. In cats anesthetized with chloralose, an immediate acute fall in arterial pressure, accompanied by a varying degree of bradycardia was followed by an equilibrium state lower than the control value. Following bilateral vagotomy the initial hypotension was still present but the arterial pressure during the second phase returned to the preoxygen value. With inactivation of the caroticoaortic chemoreceptor regions, no hypotensive effect was seen, but a small, slowly developing hypertension was observed, originating peripherally. A similar, but significantly smaller hypotensive effect was seen in cats under sodium pentobarbital anesthesia. No significant difference in the arterial O2 saturation between animals anesthetized with chloralose and pentobarbital was noted, but in both groups the largest fall in arterial pressure occurred with the greater degree of anoxia. Experiments in which an increased degree of anoxemia was induced demonstrated the significantly different reactivity of the chemoreflex system under the anesthetics studied and suggests the presence of a central selective depression of the tonic anoxic chemoreceptor drive with barbiturate anesthesia. Submitted on February 27, 1961
Volume-pressure relationships of lungs and thorax in fetal, newborn, and adult goats
Authors: Avery Mary Ellen , Cook Charles D. 
Published: December 2017

The physical properties of the lungs and thorax in kids before and after the onset of respiration and in older goats demonstrate changes with age. The fetal goats' lungs contained a volume of fluid which made them approximately twice as heavy as those of animals which had lived a few hours. The intrapleural pressure in the fetus was atmospheric, and was more negative the larger the goat. The pressure-volume characteristics of the lungs and thorax measured in the paralyzed, anesthetized animals show the thorax of the kid to be more compliant and the lungs of the kid less compliant per gram of lung tissue than in the older animal. Studies on excised lungs from these animals show that the lungs of older animals contain a larger gas volume per unit lung weight at pressures over 5 cm H2O than lungs of younger animals. Submitted on July 19, 1961
Pulmonary venous admixture in man during negative pressure respiration
Authors: Steiner Sheldon H. , Behnke Roy H. 
Published: December 2017

Arterial blood gases were measured after 10 min of full-phase negative pressure breathing at a gauge pressure of — 40 mm Hg. Oxygen capacity increased slightly, and oxygen saturation fell from 96.9% to 92.6% in the seated position (P < 0.05) and from 96.0% to 92.2% in the recumbent position (P < 0.05). At this transthoracic pressure differential there would be expected only an 8—10-mm decrease in oxygen tension resulting in a 1% decrease in arterial saturation. pH and calculated pCO2 were not altered. The physiological shunt appeared to increase as evidenced by the arterial desaturation. If blood is redistributed away from poorly ventilated regions, the redistribution is not complete during negative pressure breathing at this magnitude. Although there appears to be an increased shunting, it is quite small compared to that reported in the anesthetized dog at only —20 mm Hg. The differences are probably related to the effects of anesthesia causing a decrease in lung volume and tidal volume. Forward acceleration has been said to simulate negative pressure breathing. However, the arterial saturation at 8 g was 75%, and 8 g has been estimated as being equivalent to —28 mm Hg (—3.5 mm Hg/g). Therefore, the degree of arterial desaturation during forward acceleration is more reasonably related to the hydrostatic effects than to possible negative pressure breathing effects. Submitted on May 1, 1961
Effect of citrate on ultrafiltrable and ionic calcium concentrations in serum
Authors: Peterson N. A. , Crismon J. M. 
Published: December 2017

The effect of citrate on the concentration of ultrafiltrable and ionic calcium in blood serum and bovine serum albumin (BSA) solutions was studied. Theoretical equations were derived which predict the fractions of total calcium (in simultaneous equilibrium with protein and citrate) which are ultrafiltrable and ionized. The predictions were made directly from concentrations of total protein, calcium and citrate, and pH. Ultrafiltration experiments on purified BSA, rabbit serum containing added citrate, and human blood-bank serum with acid citrate dextrose solution, yielded data which were in good agreement with predicted values. Additional experiments were performed in order to obtain an empirical expression relating pH to the dissociation of calcium proteinate in normal human serum. Submitted on July 3, 1961
Effect of skin temperature on absolute threshold for electrical current
Authors: Hawkes Glenn R. 
Published: December 2017

The dependence of tactile sensitivity on skin temperature could be due to a central or a peripheral effect. Maximal cutaneous sensitivity for pressure or mechanical vibration is obtained at about 36 C, with a shift in either direction resulting in an elevation of threshold. In the present study, raising skin temperature of the finger or forearm to as much as 45 C had no effect on the threshold for electrical cutaneous stimulation. It is concluded that the dependence of sensitivity to pressure or mechanical vibration on skin temperature is a peripheral effect. Further, electrical current applied to the intact skin apparently affects nerves directly without requiring transduction by a chemical (or other) process at the receptor. It is suggested that the effect of temperature, with other kinds of cutaneous stimulation, is on chemical substances contained within the receptors. Submitted on July 20, 1961
Films from lung washings as a mechanism model for lung injury by ozone
Authors: Mendenhall Richard M. , Stokinger Herbert E. 
Published: December 2017

Saline washings of the mouse lung were layered on various hypophases. With serum dialysate present in the hypophase, film pressure in the presence of ozone increased over that in its absence. Addition of Tapazole (2-methyl-1-mercaptoimidazole) or AET (aminoethylisothiouronium bromide-HBr) protected the films from the action of ozone if serum dialysate was present in the hypophase, but film pressures were rapidly reduced in its absence. Both Tapazole and AET protect mice from otherwise lethal doses of ozone. The results indicate the presence of a surface-active film in the alveolus which, together with the hypophase upon which it resides, forms a primary barrier against production of pulmonary edema by ozone. However, this barrier, because of increase in its surface pressure, may be a primary cause of emphysema produced in animals by long-term exposure to ozone. Destruction of the surface-active material of the barrier should produce atelectasis and/or pulmonary edema as a result of increased surface tension. Submitted on May 22, 1961
Reduction of cardiac work during venous blood perfusion of lower body
Authors: Wyman Milford G. , Weil Max H. , Blankenhorn David H. 
Published: December 2017

A system of venoarterial perfusion was established in the adult dog, simulating that which normally exists in the mammalian fetus. Blood was passively drained from the inferior vena cava by way of both femoral veins, and continuously infused through a catheter inserted into the femoral artery in the abdominal aorta at its bifurcation. The system was adjusted so that approximately 50% of normal cardiac output was provided by the extracorporeal system. Indicator dilution and oxygen saturation measurements showed that the output of the heart was reduced by an amount approximately equal to the output of the pump. In the aorta, an abrupt change in oxygen saturation occurred 5 cm cephalad to the infusion catheter. A prominent continuous murmur was detected at this site. The pulse rate, peripheral resistance, and central blood volume were reduced. Cardiac output was decreased to 55% and stroke work to 50% of the control value. There was a slight fall of pH and pCO2 of arterial blood. This system of assisted circulation effectively reduces the work load on the heart, and may be a promising technique for the treatment of heart failure accompanied by venous congestion. However, these experiments indicate that it appears less promising for the treatment of hypotension and shock due to peripheral circulatory failure when venous return is deficient. Submitted on April 24, 1961
Postsystolic myocardial augmentation: physiological considerations and technique
Authors: Watkins David H. , Duchesne E. Ronald 
Published: December 2017

Technique and appropriate equipment are reported which remove blood from the circulation during cardiac systole, thereby reducing intraventricular systolic blood pressure and the work of systolic ejection. Blood is reinjected during ventricular diastole, so that the diastolic blood pressure and coronary blood flow are increased. An electronic circuit enables the phasing of the augmenting systole to be placed accurately in relationship to the QRS complex of the EKG. Application of the technique to experimental heart failure induced by norepinephrine and hemorrhage is illustrated. Cardiac dilatation, elevated end-diastolic pressures, and arterial hypotension are reversed by the use of this technique. In addition, it is possible to supply an unlimited quantity of oxygenated, banked, standard venous blood to the ascending aorta via intra-arterial cannulas. The technique which we have developed overcomes difficulties previously experienced by those who wished to withdraw blood during systole and reinject it during diastole. The size of the pump is adequate to change the blood pressure effectively; the timing of reinjection is such as to accomplish reinjection during the short period of ventricular diastole. Submitted on May 8, 1961
Areas of dye-dilution curves sampled simultaneously from central and peripheral sites
Authors: Bassingthwaighte James B. , Edwards Anthony W. T. , Wood Earl H. 
Published: December 2017

The assumption that the rate of blood flow past the sampling site is constant is basic to the Stewart-Hamilton estimation of cardiac output. Pulsatile flow might be expected to cause random and systematic errors. In this study dye-dilution curves were recorded simultaneously from two or three sites (pulmonary artery, aortic root, thoracic aorta, femoral artery) after injections of dye into the inferior vena cava, right ventricle, pulmonary artery, or left atrium of anesthetized dogs. The color of the indocyanine-protein complex formed after injection of the dye stabilized rapidly. Such stabilization is required for continuous photometric quantitation of dilution curves with juxtaposed injection and sampling sites. Areas of curves from the central circulation did not differ significantly from each other; they averaged 2.5% less than areas of curves recorded simultaneously from the femoral artery. Heart rate had no consistent influence. The large variability in estimates of cardiac output from curves recorded from the pulmonary artery after injection into the right ventricle was diminished with injection farther upstream. Submitted on May 29, 1961
Absorption of various inert gases from subcutaneous gas pockets in rats
Authors: Piiper J. , Canfield R. E. , Rahn H. 
Published: December 2017

A study was made of absorption of the inert gases, helium, argon, hydrogen, nitrogen, sulfur hexafluoride, nitrous oxide, and cyclopropane, from subcutaneous gas pockets in rats breathing oxygen. For interpretation of the data a method of analysis was devised which permitted distinction between perfusion and diffusion as factors limiting the absorption rate. Application of this method to the experimental data leads to the conclusion that both perfusion and diffusion limitation were effective in determining the absorption rates of the inert gases, diffusion limitation being the more important factor. The blood flow responsible for the uptake of inert gas from the gas pocket, and the thickness of the tissue layer between blood and pocket gas could be crudely estimated. Submitted on October 9, 1961
Ventilation of terminal air units
Authors: Storey Winnifred F. , Staub Norman C. 
Published: December 2017

We have used a rapid-freeze method to stop mechanical changes in the living lung in 0-10 sec and have adapted histological techniques to prepare thick three-dimensional sections from which diameters of alveoli and alveolar ducts were determined for lungs at two volumes, functional residual capacity and high lung volume, during positive-pressure ventilation. Diameters of both alveoli and ducts increase 30% from the lower to the higher lung volume. The calculated surface area of alveoli increases 70%. The volumes of alveoli and ducts were calculated to increase about twofold. The ventilation unit of the lung includes the alveolar ducts with their associated alveoli stemming from one respiratory bronchiole. The distribution of inspired gas to the respiratory surface of the lung is not determined by hundreds of millions of individual alveoli but by these larger ventilation units. Submitted on September 5, 1961
Influence of body weight on energy expenditure
Authors: Malhotra M. S. , Ramaswamy S. S. , Ray S. N. 
Published: December 2017

Energy expenditure in a group of 58 adult male subjects has been studied for marching, rifle drill, parade, physical training, bayonet fighting, cycling, sitting, and standing, using the method of indirect calorimetry. For all these tasks a linear relationship between energy expenditure and body weight has been established. Submitted on September 5, 1961
Effect of oxygen inhalation on manual performance in the cold
Authors: MacCanon D. M. , Eitzman D. D. , Abbott J. E. 
Published: December 2017

The effect of oxygen inhalation on block-stringing performance of 12 subjects was studied at hand temperatures of 32.7 C in a control room environment of 29 C and after cooling the hands to 16.0 C in a cold (5 C) environment. A similar slight but significant improvement in manual performance accompanied oxygen inhalation under both conditions. This is interpreted as indicating the existence of suboptimal neural and/or muscular activity during air breathing in both situations. If hand cooling had affected the same neural and/or muscular elements as oxygen, lowering activity even further from the optimal level, this should have exaggerated the O2 effect. In view of the absence of such a response, it would seem that hand cooling and oxygen influence different neural and/or muscular elements, and their effects on manual performance are not directly related. Submitted on August 31, 1961
Evidence for local arteriovenous reflex in intestine
Authors: Hanson Kenneth M. , Johnson Paul C. 
Published: December 2017

Studies were made on the hemodynamics of the isolated autoperfused dog intestine preparation. An attempt was made to explain the mechanism involved in the observed increase in venous resistance seen as the arterial pressure in the segment was reduced. This rise in venous resistance was reduced or abolished by sympatholytic agents (phentolamine and Dibenzyline) and by local anesthetics (tetracaine). When areas of intestine were surgically denervated and then subjected to hemodynamic studies 10–19 days later the venous resistance response was nearly or completely absent in all cases. The response was not significantly affected by the infusion of hexamethonium or dichloroisoproterenol or by changes in hematocrit ratio. It was concluded that the rise in venous resistance seen as arterial pressure is reduced is mediated by a local sympathetic axon reflex with the receptor on the arterial side of the circulation and the effector located on the venous side. The decrease in arterial resistance seen as arterial pressure is reduced (autoregulation) is also discussed. None of the drugs mentioned above or chronic denervation had any effect upon this phenomenon, strengthening the concept that it is the result of a myogenic response of the arterial vessels. Submitted on November 6, 1961
Oxygen debt, lactate, pyruvate, and excess lactate after muscular work
Authors: Knuttgen Howard G. 
Published: December 2017

The effect of activity of large muscles at different work intensities on oxygen debt and on lactate, pyruvate, and excess lactate during work and recovery has been studied. Data are presented for the more extensive testing program conducted on one research subject. Four series of experiments were conducted with the subject riding a Krogh bicycle ergometer at work rates of 300, 700, 1,100, and 1,600 kg-m/min. O2 debts were contracted at each of the work levels, but no appreciable rises in excess lactate and only small rises in total lactate were found at the lower two intensities. When a critical level of work (O2 uptake of 1.5 liters/min with an accompanying debt of 1.5 liters) was surpassed there was a rapid rise in O2 debt values which was parallel to rises in O2 equivalence values for both total lactate and excess lactate. At all work levels the O2 debt surpassed in quantity the O2 equivalents of the maximum increases in total lactate and, to an even greater extent, the O2 equivalents of excess lactate. This finding supports the theory of separate alactacid and lactacid portions of the O2 debt. No conclusions could be drawn concerning the rates or methods of payment of the two portions. Submitted on October 23, 1961
Frequency-dependent compliance in the rabbit before and after sarin administration
Authors: Shephard Roy J. 
Published: December 2017

Static and dynamic pulmonary compliance have been studied in 16 rabbits anesthetized with sodium pentobarbital, and ventilated by intermittent positive pressure pump. Functional residual volume increased at inflation rates of 56/min and above, and compliance decreased at rates greater than 60–70/min. These changes are interpreted as a distention of lung units with a long time constant. Following inhalation of sarin (isopropyl methylphosphonofluoridate) 12–120 μg/kg, the static compliance was slightly decreased, but there was no indication of an increase of gas trapping unless the dose of sarin was sufficient to cause death. Sarin accentuated the effects of increasing inflation rate by increasing the time constant of all lung units. Submitted on October 20, 1961
Nerve conduction velocity and refractory period in peripheral vascular disease
Authors: Miglietta Osvaldo , Lowenthal Milton 
Published: December 2017

The conduction velocity and the residual latency of the common peroneal nerve and the refractory period of the extensor digitorum brevis were measured in a group of patients with occlusive vascular disease of the lower extremity, and compared with those of a group of normal and elderly subjects. The results indicate that motor nerve and muscle are affected in peripheral arteriosclerosis. The conduction velocity showed a decrease of 16.9% for the patient group and of 6.7% for the elderly normal subjects when compared to the young group. The refractory period of the extensor digitorum brevis, after 10 min of provoked ischemia and 2/sec stimulation, increased 105.1% in the patient group, 17.8% in the young, and 28.9% in the elderly group. Correlations between the electrical responses and the state of muscle and nerve as influenced by chronic arteriopathy are discussed. Submitted on October 26, 1961
Blood Pco2 and brain oxygenation at reduced ambient pressure
Authors: Pierce E. C. , Lambertsen C. J. , Strong M. J. , Alexander S. C. , Steele D. 
Published: December 2017

Hyperventilation during breathing of 100% oxygen elevates the Po2 of alveolar gas by the same amount that it lowers its Pco2. Since the development of arterial hypocapnia causes cerebral vasoconstriction, brain oxygenation is drastically decreased even while arterial oxygenation is improved by hyperventilation. Administration of 30% CO2 with oxygen at an ambient pressure equivalent to that at 39,000-ft altitude prevented alkalemia and, in spite of hyperventilation, restored cerebral venous oxygenation to a level at least equivalent to that found when pure oxygen was breathed at rest at the same altitude. The respiratory minute volume during administration of CO2 with O2 was greater than when O2 alone was breathed at reduced ambient pressure. Since neither arterial Po2 nor cerebral venous Pco2 values differed in these two experimental situations, the respiratory stimulation may represent the quantitative demonstration in man of a respiratory effect of CO2 mediated by arterial chemoreceptor activation and unrelated to change in the level of central chemical stimulus. Submitted on March 16, 1962
Uptake of O2 and CO by hemoglobin in sheep erythrocytes at various temperatures
Authors: Sirs John A. 
Published: December 2017

Spectrophotometric observations were made with the stopped-flow method on the rate of uptake of CO and O2 by hemoglobin in intact sheep erythrocytes at temperatures between 5 and 37 C. Both rates were found to increase by roughly 1.5 for each 10 C rise. On the basis that diffusion through the cell membrane is involved, energies of activation for this process are calculated as 4,350 cal/mole for O2 and 5,900 cal/mole for CO. The addition of silver, copper, magnesium, and lead ions were found to significantly increase these rates Submitted on September 21, 1961
Motor innervation and pattern of activity of cat diaphragm
Authors: Sant'Ambrogio G. , Frazier D. T. , Wilson M. F. , Agostoni E. 
Published: December 2017

The segmental motor innervation of the costal and vertebral parts of the diaphragm of the cat has been studied by means of electromyography. The changes in electrical activity following successive sections of the cervical roots show that the costal region is innervated partly by C4 but mainly by C5, while the vertebral part is innervated partly by C5 and mainly by C6. After unilateral section of C4, C5, and C6 no diaphragmatic electrical activity remained on the ipsilateral hemidiaphragm. Section of the right phrenic nerve in the chest eliminates all electrical activity in the ipsilateral hemidiaphragm. Following a similar section of the left phrenic nerve, some rhythmic electrical discharge is still recorded from the corresponding hemidiaphragm. Only after section of the contralateral phrenic nerve does this residual activity disappear. Therefore, a few fibers must leave the left phrenic nerve and reach the diaphragm with the right phrenic nerve. Apparently these fibers cross the midline within the diaphragm and contribute to the motor supply of its left side. The pattern of the electrical activity of the costal and vertebral parts of the diaphragm is similar. Generally, no activity is present during the last part of expiration. Submitted on July 9, 1962
Effect of alveolar hypoxia on zonal distribution of pulmonary blood flow
Authors: Fowler K. T. , Read John 
Published: December 2017

Redistribution of pulmonary blood flow was studied by means of the cardiogenic oscillations of expired gas tensions in six normal subjects after induction of alveolar hypoxia (13.5% O2 inspired). In three subjects the upper zones of the lungs were found to receive a considerably greater proportion of total pulmonary blood flow during hypoxia in both vertical and horizontal postures. Two subjects showed no redistribution in either position. The response of one subject was intermediate between these two groups. It is concluded that in some subjects there is no pulmonary vascular response to alveolar hypoxia, whereas in others there is a response consisting of preferential lower-zone vasoconstriction of greater or lesser magnitude. Earlier data on the effects of hypoxia on the pulmonary circulation are shown to be consistent with the operation of this mechanism. Submitted on July 16, 1962