bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of pulmonary artery occlusion upon end-tidal CO2 tension
Authors: Julian Desmond G. , Travis David M. , Robin Eugene D. , Crump Charles H. 
Published: December 2017

Occlusion of branches of the pulmonary artery has been performed in dogs to determine its effect upon the relationship between peak end-tidal and arterial carbon dioxide tension. The use of the formula (See PDF) to express the percentage of alveolar space which is ventilated but not perfused has been tested by its application to the values encountered when one main pulmonary artery is occluded and when a smaller branch is occluded. This formula is found to express approximately the percentage unperfused. Submitted on August 15, 1958
Effect of exercise, immobilization and intermittent stretching on strength of knee ligaments of albino rats
Authors: Rasch Philip J. , Maniscalco Ruth , Pierson William R. , Logan Gene A. 
Published: December 2017

Sixty male albino rats were divided into four groups. The rats in the first group were exercised; those in the second were subjected to intermittent passive stretching of one hind leg; those in the third group had one hind leg immobilized; those in the fourth group served as controls. At the end of 4 weeks, all animals were sacrificed and the muscle tissue was dissected from the hind legs. The limbs were then torn apart at the knee joint. No significant differences were found in the amount of stress required to tear the knee ligaments in the various groups. Submitted on September 29, 1959
Mechanical work of breathing during muscular exercise
Authors: Margaria R. , Milic-Emili G. , Petit J. M. , Cavagna G. 
Published: December 2017

The mechanical work of breathing was measured during muscular exercise on three normal subjects from simultaneous records of intra-esophageal pressure and tidal volume. At the maximal values of ventilation attained during exercise, the mechanical work of breathing amounts to about 100–120 cal/min. The maximum pulmonary ventilation useful for external work is attained when the energy cost of breathing due to any additional unit of air ventilated (dWre/dV) equals the additional energy provided by the same change in ventilation (dWtot/ dV), i.e. when dWre/dV = dWtot/dV. The maximal values of ventilation obtained experimentally during muscular exercise are in good agreement with that assumption, if the mechanical efficiency of the respiratory muscles is taken as 0.25. This implies that the mechanical efficiency of the respiratory muscles is the same as that of the muscles involved in performing useful external work. The work of breathing is of relatively small magnitude: during exercise the work of a breathing cycle amounts, at maximum, to 8% of the maximum potential work of breathing, calculated from the pressure-volume diagram of the respiratory apparatus, and the energy cost of respiration represents no more than 3% of the total energy consumed by the subject. Submitted on May 21, 1959
Effects of conditioning on the ballistocardiogram of college basketball players
Authors: Montoye Henry J. , Collings W. Doyne , Stauffer Gordon C. 
Published: December 2017

This study was undertaken to investigate the effects of vigorous athletic training on the ballistocardiogram. Ten varsity college basketball players were tested twice before the season began, twice during the season, and once from 4 to 6 weeks after the season was concluded. Ballistocardiograms were recorded before and after a standard exercise at each testing period. While the heart rates, particularly after the standard exercise, decreased with training, there was no statistically significant effect of training on the ballistocardiogram. This was thought to be due to limitations of the direct-body ballistocardiograph, particularly as influenced by changes in skin-fold fat of the subject. The immediate effects of exercise were an increase in amplitude and areas of the I plus J waves and the amplitude of the K wave. No immediate effects of exercise or of training were observed on the I-J or J-K intervals or on the respiratory effects on the ballistocardiogram. Submitted on October 1, 1959
Comparison of dye-dilution and flowmeter estimates of pulmonary valve incompetence in dogs
Authors: Korner P. I. , Uther J. B. , Chalmers J. P. , Nicks R. 
Published: December 2017

Quantitative estimates of backflow were obtained in dogs with experimental pulmonary valve incompetence by means of a bristle flowmeter and the dye curve variance method. The variance of the curve was found to be the best index of indicator dispersion and is calculated from analogy to a frequency distribution curve. The method postulates that (forward flow + backflow)/forward flow = variance observed during incompetence/Vx(F; V), where Vx(F; V) is the expected variance for the same forward flow and volume between injection and sampling sites and is determined from regression equations calculated from data of normal dogs. There was good agreement between dye and flowmeter results, provided that Vx(F2;V) was estimated for the specific regression equations obtained from individual dogs. Three or four successive dye curves, obtained while the animal was in a steady state, permitted quantitation of backflow with the accuracy of a single determination of forward flow by the direct Fick or dye method. When Vx(F;V) was estimated from regression equations obtained from the pooled data and normal dogs, agreement with the flowmeter estimates was poor. Submitted on October 28, 1959
Manual performance as a function of rate of change in hand skin temperature
Authors: Clark R. Ernest , Cohen Alexander 
Published: December 2017

Manual performance (knot tying) was studied as a function of fast and slow rates of cooling during cold exposure and during subsequent rewarming. It was found that performance decrements accompanying cold exposure were sizeably increased as the rate of cooling decreased. These increased decrements associated with slow cooling perseverated even after the hands had been rewarmed to precooling temperatures. In addition, the results indicated a direct relationship between rate of cooling and rate of rewarming. Submitted on November 30, 1959
Pulmonary capillary blood volume, flow and diffusing capacity during exercise
Authors: Johnson R. L. , Spicer W. S. , Bishop J. M. , Forster Robert E. 
Published: December 2017

Pulmonary capillary blood flow (Qc) and apparent CO diffusing capacity (Dl) were calculated from the rates of disappearance of small alveolar concentrations of inspired acetylene and carbon monoxide during breath holding. Such measurements were performed simultaneously in four normal subjects at rest, during exercise and while performing Valsalva or Mueller maneuvers; they were also made at more than one alveolar oxygen tension so that true membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) could be calculated by the method of Roughton and Forster. Dl, Dm and Vc were closely correlated with Qc (r = 0.92, 0.71 and 0.92, respectively), indicating that both volume and effective surface of the pulmonary capillary bed changed along with corresponding directional changes in blood flow. During transients after starting or after stopping exercise, changes in Dl lagged slightly behind the associated changes in Qc; both parameters tended to reach steady values, however, after about 1 minute of steady exercise. The average time spent by red cells in the pulmonary capillaries at rest was estimated to be 0.79 second, falling to about 0.5 second at levels of exercise at which volume flow through the capillary bed was approximately tripled. Submitted on September 18, 1959
Vagal inhibition of the heart in deep hypothermia
Authors: Adolph E. F. , Nail R. L. 
Published: December 2017

Rats were cooled to 16°C esophageal temperature; the vagi were exposed. As the rats were further cooled one vagus was stimulated to produce bursts of impulses of varying frequencies. At low temperatures a lesser frequency of vagal stimulation and a greater intensity were required to produce inhibitory vagal impulses than in euthermia. Electrocardiographic tracings recorded the heart beats. Vagal impulses sharply decreased the heart frequency at all temperatures down to 12°C. Between 12° and 8°C the effect disappeared reversibly. Atropine blocked the vagal effect at the low body temperatures (16°C) as well as at high ones. Evidently vagal impulses may affect the heart rate at temperatures nearly as low as those at which the heart ceases to beat. Submitted on April 4, 1960
Physiological index of strain and body heat storage in hyperthermia
Authors: Hall John F. , Polte J. W. 
Published: December 2017

Individual variability of a modified Craig index of physiological strain and body heat storage was determined, and the relationship between these parameters defined for five healthy, nonacclimatized male subjects exposed five times to each of three heat stress levels: 38°C, 54°C and 71°C at a vapor pressure of 10 mm Hg. This index contains the variables of heart rate, sweat rate and rate of rectal temperature change, measured by EKG, nude pre- and post-experimental weighings, and a rectal thermistor, respectively. Body heat storage was calculated from initial and terminal weighted mean skin and rectal temperatures. Subjects were sitting and wore 1 clo of body insulation. Individual and group variation for strain index and body heat storage was determined. The data show a linear relationship between these expressions over the thermal stress range investigated although individual variability was considerable at the higher stress levels. A statistically significant correlation between strain index and body heat storage is shown. Submitted on May 16, 1960
Blood-borne vasodilating agent from ischemic tissues
Authors: Freeburg B. R. , Hyman Chester 
Published: December 2017

Plethysmographic measurements of forearm blood flow show a drop to minimal values immediately after release of arterial occlusion of a leg; this is soon followed by a somewhat greater and more sustained increase to values above the control. Prepacking the leg with blood before arterial occlusion, or exercise before occlusion, or a combination of these procedures does not significantly alter the response. Calculated peripheral resistance in the forearm follows the pattern implied by the blood flow changes. It is suggested that the initial vasoconstriction is a reflex whereas the later vasodilatation is due to a stable, circulating agent from the previously ischemic leg. Submitted on April 29, 1960
Serum elastase inhibitor levels in pregnancy and under endocrine influences
Authors: Schneider Robert B. , Walford Roy L. , Dignam William J. 
Published: December 2017

Serum elastase inhibitor is significantly elevated during pregnancy both in the human and in the rat, but not in the rabbit. In humans the change is progressive, reaching an average value by parturition of three times the value for nonpregnant women or for 6 weeks postpartum women. Injection of ACTH, progesterone, and estrogen separately into nonpregnant female rats failed to produce significant or corresponding alterations in serum elastase inhibitor levels in these animals. Submitted on July 5, 1960
Physiological reactions of men and women during muscular activity and recovery in various environments
Authors: Brouha L. , Smith P. E. , De Lanne R. , Maxfield M. E. 
Published: December 2017

Men and women performing a standard exercise were studied in three environments. Pulmonary ventilation, O2 consumption, CO2 elimination, heart rate, blood pressure, body temperature and weight loss were recorded. Pulmonary ventilation was usually decreased in the warm-dry environment and increased in the warm-humid. Oxygen consumption was significantly lower in the warm-dry environment than at room temperature. The pattern of changes of these two functions was similar for both sexes. Respiratory exchange ratios were not influenced by sex, but were higher in the warm-dry environment. Increase in body temperature was found only in the warm-humid environment, with a smaller weight loss than in warm-dry conditions. Systolic blood pressure was influenced by work load but not by environments. Diastolic pressure varied little for both sexes under all conditions. Heart rate was significantly influenced by sex and environment, being highest for the women in the warm-humid conditions. Cardiac cost increased and cardiac efficiency decreased in both warm surroundings, more so for women than for men. Submitted on May 16, 1960
Effects of relatively high accelerations on some biological systems
Authors: Slonim Arnold R. 
Published: December 2017

Fasting male subjects were exposed to forward accelerations (12-degree back angle) at fatiguing levels varying both in amplitude and duration, nonfatiguing levels and mock runs, and to treadmill exercise. The following analyses were made: plasma bicarbonate, blood glucose, phosphorus and creatinine, urine creatinine, urine volume, urinalysis, and an estimate of creatinine clearance. The only consistent change noted after fatiguing accelerations was a small rise in blood creatinine ( P < 0.05). Exercise, however, resulted in a marked ( P < 0.01) decrease in bicarbonate, rise in blood creatinine, and drop in clearance. Accelerations in comparison to exercise showed little effect on either muscular or renal activity. No correlation was found between any of the biochemical measurements and acceleration intensity nor were there any differences noted between real and mock accelerations, indicating that none of these tests could index the severity of accelerative stress. The fatigue associated with high accelerations is not easily explainable in terms of increased muscular activity. Submitted on August 3, 1960
Isotope external counting method for cardiac output analyzed in glass model circulation
Authors: Gorten Ralph , Gunnells J. Caulie 
Published: December 2017

Certain aspects regarding degree of accuracy and some of the theoretical sources of error of the isotope-external counting method for determination of cardiac output have been further evaluated by the use of a glass model central circulation. By comparing calculated flow with actually timed flow, and by observing the constant relationship between dilution curve area and flow, it was found that single as well as multichambered systems could be used for this method with valid and reproducible results. Variations in chamber size, rate of flow, isotope dosage and instrument settings were used to evaluate some of the possible sources of error. Variable mixing was the most important factor responsible for discrepancies. Errors in extrapolation of the primary dilution curve to zero and instrumental lag were considered to be of less importance and can most often be avoided. A change in the recording time constant altered the curve shape, and therefore the calculated mean transit time, but not curve area and calculated flow. Submitted on July 6, 1960
Effect of norepinephrine on plasma free fatty acids level in man
Authors: Klein Robert F. , Estes E. Harvey , Bogdonoff Morton D. 
Published: December 2017

Plasma free fatty acid (FFA) and glucose levels were measured in 44 young male subjects who received intravenous infusions of norepinephrine. Dose levels and rates of infusion were independently varied. A significant dose-response relationship was noted for FFA. The time at which the peak response occurred depended on the duration of infusion. A postinfusion fall in FFA level was observed, which suggests that exogenous infusion of norepinephrine may inhibit endogenous lipid-mobilizing mechanisms. Submitted on October 11, 1960
Steroid pyrogen studies in laboratory and domestic animals
Authors: Palmer Robert H. , Ratkovits Bela , Kappas Attallah 
Published: December 2017

The 5β-H steroid hormone metabolites, etiocholanolone (3α-hydroxyetiocholan-17-one), pregnanolone (3α-hydroxypregnan-20-one) and 11-ketopregnanolone (3-hydroxypregnan-11, 20-dione) were administered by intramuscular, intravenous and intrathecal injection in doses of 1.0 and 5.0 mg/kg body weight to various species of animals including cats, dogs, rats, mice, guinea pigs, rabbits, monkeys, sheep, steers, burros and pigs in order to determine whether these species were susceptible to the pyrogenic action of steroids. In addition, certain animals received injections of the 5-H steroid metabolite, androsterone (3α-hydroxyandrostan-17-one). None of these animals developed pyrogenic responses to these steroid hormone transformation products indicating that the fever-producing action of 5β-H steroid metabolites previously noted in human beings is apparently a form of biological activity which is highly species specific. Submitted on November 16, 1960
Relationship between body fat and shivering in air at 15 C
Authors: Daniels Farrington , Baker Paul T. 
Published: December 2017

Thirty-one men of widely varying body fat content were exposed to air at 15.2 C for 2 hr. Rectal and skin temperatures and metabolic rates were measured at 10, 40, and 80 min and at the end of the 2 hr. Shivering was rated on a five-interval scale. Under these conditions thick subcutaneous fat provided insulation as indicated by lower skin temperatures, less shivering, and lower oxygen consumption in the fatter men. The findings rule out simple relationships between measured temperatures and shivering, leading to other possibilities and approaches to the study of shivering. Submitted on October 3, 1960
Relation between alveolar surface tension and pulmonary vascular resistance
Authors: Thomas Lewis J. , Roos Albert , Griffo Zora J. 
Published: December 2017

In order to examine the hypothesis that surface forces at the alveolar air-liquid interface may play a role in determining the course of pulmonary vascular resistance on negative-pressure inflation, resistance was studied as a function of lung volume for both air and dextran-filled dog lungs in excised preparations perfused with fresh dog blood under carefully controlled conditions. Results show that abolishing the interface by liquid filling does not alter the course of resistance significantly. It is thus concluded that the presence of the interface can have only a minor effect on the course of resistance and that purely volume-dependent factors are primarily responsible. Submitted on September 19, 1960
Elevation gradient of intrathoracic pressure
Authors: Krueger John J. , Bain Thomas , Patterson John L. 
Published: December 2017

Intrathoracic (intrapleural) pressure was measured in 15 anesthetized mongrel dogs held in the vertical position. A small balloon attached to a polyethylene catheter was inserted, without admission of air, into the chest through the 3rd intercostal space, or above the first rib, and passed down to the costophrenic sulcus. Along the lateral, anterolateral, and posterolateral aspects of the lung surface a vertical gradient of pressure was found, amounting to an increase of +0.21 cm H2O/cm descent, which was absent when the animal was in the horizontal position. This pressure gradient agrees closely with the gradient predicted on the basis of the mean density of lung tissue at end expiration in these animals. Among the implications of these findings is the possible existence of regional differences in the elastic work of breathing, based on differences in vertical distance between parts of the lung. Submitted on May 2, 1960
Blood distribution during cardiac arrest induced by hypothermia
Authors: Willard Paul W. , Horvath Steven M. 
Published: December 2017

Blood volumes with simultaneous blood- and red cell-distribution measurements were determined by the Cr51 technique in four groups of rats. In splenectomized and nonsplenectomized animals, blood volume of the whole body, lung, spleen, liver, kidney, heart, diaphragm, and gastrocnemius muscle was measured in both the control rats (body temperature 37 C) and in rats with hypothermically induced cardiac arrest (body temperature 8–9 C). Splenectomy caused alterations in some visceral blood volumes without concurrent changes in red cell mass. With cardiac arrest increased quantities of blood and red cell mass were observed in the lung, liver, and gastrocnemius in both splenectomized and nonsplenectomized groups. In the nonsplenectomized animals an increase of over 100 % in spleen blood volume was observed. When the two hypothermic groups were compared, differences existed only in blood volume of the lung, heart, and kidney. Hypothermia induced a pattern of blood redistribution toward visceral areas of the body. Submitted on October 14, 1960
A trapezoidal-wave electromagnetic blood flowmeter
Authors: Yanof Howard M. 
Published: December 2017

A new, electromagnetic blood flowmeter is described which has been designed to provide the physiologist with a reliable instrument allowing the measurement of blood flow in the unbroken blood vessel. The transducer has been made small enough to allow implantation in the animal for relatively long periods of time. In this way the flow in a number of vessels can be measured simultaneously in the unanesthetized animal. This flowmeter is different from existing flowmeters because of the unique trapezoidal-wave current that energizes the magnet. A method for calibrating the instrument is described and data is presented showing the femoral artery flow in response to epinephrine and norepinephrine, and hepatic artery flow in response to norepinephrine. Note: (With the Engineering Assistance of Paul Salz) Submitted on January 16, 1961
Effect of uneven ventilation on pulmonary diffusing capacity
Authors: Lewis Benjamin M. , Hayford-Welsing E. J. , Furusho Akio , Reed L. C. 
Published: December 2017

In four normal subjects measurements of steady state diffusing capacity for CO (DLCO) by an alveolar sample technique and of the degree of uneven ventilation by nitrogen washout were made simultaneously followed by measurement of DLCO by rebreathing. A methacholine-histamine aerosol was then given. After this aerosol uneven ventilation worsened and steady state DLCO fell, while rebreathing DLCO did not change. Relief of uneven ventilation by isoproterenol was followed by increase of steady state DLCO in two subjects. Alterations in rate and depth of breathing or changes in functional residual capacity do not explain the changes in steady state DLCO which are attributed to increase in uneven ventilation as predicted by the theory of CO absorption. Theory also predicts a lack of effect of uneven ventilation on the rebreathing DLCO, but these results must be accepted with caution because deep breathing may reverse the effects of the methacholine-histamine aerosol and O2 consumption during rebreathing rises after this aerosol. Submitted on December 30, 1960
Pulsatile gas flow in bronchi caused by the heart beat
Authors: West J. B. , Hugh-Jones P. 
Published: December 2017

Pulsatile gas flow in lobar and segmental bronchi synchronous with the heart beat has been measured during routine diagnostic bronchoscopy, using a new type of flowmeter. Pulsations were detected in three-quarters of the 60 patients examined, and occurred in all parts of the lung though they were more marked on the left side. They were seen both during inspiration and expiration, but were most obvious in the postexpiratory pauses. At a given instant in the cardiac cycle, the phase of the pulsations was sometimes different in different parts of the lung, gas going into some lobes and coming out of others. Volume flow rates up to 2.5 liter/min and displaced volumes up to 5 ml were recorded. The pulsatile flow is probably caused by changes in volume of the beating heart, and by its movements within the chest so that some parts of the lung are compressed while others expand. Because of their size and frequency, the pulsations promote mixing of the anatomical dead-space gas with alveolar gas. Submitted on October 10, 1960