bluuebunny/crossref_metadata_2025 huggingface dataset:
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
Heat reactions of some Bantu tribesmen in southern Africa
Authors: Wyndham C. H. , Strydom N. B. , Williams C. G. , Morrison J. F. , Bredell G. A. G. , Peter J. , Van Graan C. H. , Holdsworth L. D. , Van Rensburg A. J. , Munro A.
Published: December 2017

Samples of 20 Bantu each from various tribes in southern Africa have been subjected in the late summer in Johannesburg to the established “standard heat-stress test” and were compared with a sample of mixed Bantu, studied in Johannesburg in the late winter. The mean rectal temperatures of the summer group were significantly lower than the mean of the winter group. Heart rates and sweat rates were not different. Intertribal comparisons revealed no significant differences in resting values or in heat reactions. An outstanding feature was that only 3 men of the 120 unacclimatized Bantu reached a rectal temperature of 104 F, and only one collapsed (this is 3% compared to the 50% of Caucasians who did not complete the test). No distinctions can be made between these Bantu tribes in their states of acclimatization in spite of the fact that some came from temperate and others from subtropical regions. The range of climates in the tribal territories is, however, small. Expressed as basic effective temperatures, the January climates—a hot, summer month—vary from 71 to 79 F in these different region

physiological reactions of Bantu tribesmen

Submitted on September 17, 1963
Specific gravity of human subjects by air displacement and helium dilution
Authors: Hix V. M. , Pearson A. M. , Reineke E. P.
Published: December 2017

Body volumes for 24 men and 24 women were determined using both the air-displacement and helium-dilution procedures. Specific gravity values were calculated and computed. The two methods of determining body volume showed extremely good agreement, with a correlation of 0.99 for both men and women. The correlation between specific gravity values was 0.96 for men and 0.91 for women. Thus, the over-all agreement between the two methods was relatively good, although the mean deviation was relatively large. The major sources of error for the helium-dilution procedure appeared to be due to changes in temperature, to irregular accumulation of carbon dioxide within the chamber, and to difficulty in setting the current to the thermal conductivity cell at precisely the same level. The major sources of error in the air-displacement method seemed to be due to changes in temperature, changes in relative humidity, and lack of precision in making pressure readings on the manometer.

body composition; body volume by air displacement; body volume by helium dilution; specific gravity measurements

Submitted on October 28, 1963
Hypoxic pulmonary hypertension of the calf with denervation of the lungs
Authors: Reeves John T. , Leathers James E.
Published: December 2017

Transection of the spinal cord at the level of C2, spinal anesthesia, and/or bilateral vagotomy were done in 11 healthy young male calves. These procedures did not block the pulmonary arterial pressure rise with 12 or 9% oxygen, but they did block the increase in heart rate and systemic arterial pressure which accompanied hypoxia when the central nervous system was intact. The central nervous system, therefore, appeared to mediate the response to acute hypoxia of the systemic circulation, but not the pulmonary arterial pressure rise.

hypoxia; pulmonary circulation; spinal cord section; spinal anesthesia; vagotomy

Submitted on February 19, 1964
Effect of tubocurarine on respiratory and nonrespiratory muscle power in man
Authors: Johansen Sophus H. , J⊘rgensen Mogens , Molbech S.
Published: December 2017

On human volunteers the degree of muscular depression in respiratory power and handgrip strength was determined when ability to raise the head was almost or completely abolished by (+) tubocurarine. In one series the course of restitution after maximal depression of head lift, handgrip, maximal inspiratory and expiratory flows were compared. In the second series measurements of maximal inspiratory and expiratory pressures replaced those of maximal flows. In all experiments the respiratory functions were consistently much less affected than head lift and handgrip. Of the two last mentioned the power in head lift was always most affected. The results suggest that, in normal man, respiratory muscle power is relatively well preserved when curarization is carried to the point where the ability to raise the head is nearly abolished and the strength in handgrip is severely retarded.

effect on head lift

Submitted on November 15, 1963
Reactions to heat of Arabs and Caucasians
Authors: Wyndham C. H. , Metz B. , Munro A.
Published: December 2017

The physiological reactions to heat of samples of French servicemen and of Arabs in the Sahara Desert, were compared with those of South African Caucasians. Both Sahara groups displayed evidence of partial acclimatization; their reactions were better than those of the unacclimatized; but not as good as those of the acclimatized South African Caucasians. The French servicemen were slightly better acclimatized than the Arabs; they had lower rectal temperatures and heart rates, and higher sweat rates. This paradoxical finding indicates that the Arabs, although their ancestors have lived in the Sahara Desert for some centuries, display no greater adaptation to hot conditions than recent Caucasian inhabitants. The morphology of the Arab gives him a greater surface area: mass ratio than the Caucasian. This favors heat loss, but under the test conditions the Arabs had no apparent advantage in physiological reactions. The differences in morphology of the Arab and Caucasian appear to be related more to their nutritional state and physical activity levels than to any structural adaptation to heat.

acclimatization to heat in Sahara Desert; adaptation to heat of Arabs; Caucasians and Arabs in Sahara Desert; heat reactions in the desert; morphology and adaptation to heat

Submitted on February 28, 1964
Effect of O2 at high ambient pressure on blood flow and O2 consumption of the kidney
Authors: Rennie D. W. , Knox F. G.
Published: December 2017

Renal blood flow of chloralosed dogs, measured while they breathed 100% O2 at ambient pressures of 1, 2, 3, and 4 atm abs (OHP), declined exponentially as an inverse function of PiOO2 until at 4 atm O2 it was 57% of control. Denervating the kidney did not affect the response, the mechanism of which remains unknown. Mean arterial blood pressure increased to 112% of control and heart rate decreased to 60% of control as O2 pressure increased from 1 to 3 atm abs, suggesting a generalized systemic vasoconstriction in which the kidney participated. We estimate that the measured decrease in renal blood flow during OHP would account for approximately 20% of the total decrease in peripheral blood flow. Renal O2 consumption was not affected by OHP. This can be accounted for in terms of a constant filtered and reabsorbed sodium load

Note:

(With the Technical Assistance of D. R. Wilson)

hyperbaric oxygenation; kidney circulation; environmental pressure

Submitted on February 20, 1964
Changes in concentration of gases in the rubber bladders of Max-Planck respirometers
Authors: Rahaman M. M. , Durnin J. V. G. A.
Published: December 2017

Changes of concentration of CO2 and O2 through rubber bladders were determined by a) exposing the bladders to atmospheric air, b) putting them into polythene bags and inflating the bags by 1) normal expired air and 2) by the same gas mixture as inside the bladders. Two different gas mixtures (of similar percentage composition to that of expired air samples obtained during light and moderate exercise) were used. The rate of diffusion was found to depend on the partial pressure gradient across the rubber wall and the type of gas. The higher the partial pressure gradient, the more rapid was the diffusion, and CO2 diffused at a higher rate than O2. Such a simple procedure as putting the bladders into polythene bags and inflating the bags by the operator's own expired air was found to reduce the change of concentration considerably. A correction can be utilized to obtain a more accurate gaseous percentage composition if there is a delay between the experiment and the gas analysis.

carbon dioxide; oxygen; diffusion of gases; indirect calorimetry

Submitted on October 17, 1963
Physiological effects of active and passive exercise
Authors: Benjamin F. B. , Peyser L.
Published: December 2017

A comparison of the physiological effects of active and passive exercise was accomplished using two methods. In the first series of experiments, the exercise was held constant. In the second method, an attempt to match oxygen consumption was employed. The results, evaluated in view of preceding investigations in the same area, indicate that: 1) Passive exercise inincreases ventilation in excess of the metabolic need. The greater ventilation increases the ventilating equivalent and lowers the end-tidal Pco2, possibly causing respiratory alkalemia. 2) The increase in ventilation accompanying passive exercise does not produce a corresponding increase in heart rate. 3) Passive exercise increases heat production beyond the level indicated by oxygen consumption. These findings support the concept of a temperature factor being involved in the hyperventilation of exercise.

ventilation equivalent in exercise; oxygen consumption in exercise; body temperature in exercise

Submitted on March 25, 1964
Changes in tone of limb veins during supine exercise
Authors: Bevegård B. Sture , Shepherd John T.
Published: December 2017

Normal subjects have been studied to assess the response of the capacitance vessels in the forearm during supine leg exercise. Measurements were made of changes in forearm volume (strain-gauge and water-filled plethysmographs) at a given pressure in the large forearm veins, of changes in pressure in the forearm veins with the circulation to the forearm arrested and in “isolated” vein segments. The results were consistent and demonstrated that exercise with a work load of 270–810 kg/min caused constriction of forearm capacitance vessels via the sympathetic nerves proportional to the severity of the exercise. Venoconstriction also occurred in the hand, and in the calf during arm exercise. Local exercise of the forearm muscles during supine leg exercise, which increased forearm blood flow by dilating the resistance vessels, did not prevent the increase in venous tone in the forearm. Thus a reflex increase in tone in the limb veins, both in the exercising and in the nonexercising parts, contributes to the cardiovascular adaptation to exercise.

venoconstriction in exercising and nonexercising limbs; reflex venoconstriction with exercise graded to severity of work; reflex venoconstriction with exercise mediated through sympathetic nerves

Submitted on June 15, 1964
Variations in cardiac output associated with hemoglobin levels in anesthetized sheep
Authors: Halmagyi D. F. J. , Starzecki B. , Horner G. J.
Published: December 2017

Hemoglobin levels in sheep was found to be related inversely to the logarithm of cardiac index and directly to the calculated systemic and pulmonary arterial resistances over a wide spectrum of hemoglobin concentrations including the normal range. It appeared to be based on changes in blood viscosity produced by a varying red cell concentration. The continuous adjustment of hemoglobin levels and cardiac output may account for the variability of cardiac output values in normal laboratory animals and may represent a mechanism maintaining oxygen delivery to the tissues in the presence of changing oxygen carrying capacity.

blood viscosity; vascular resistance; oxygen carrying capacity

Submitted on May 15, 1964
Initial responses to added viscous resistance to inspiration in dogs
Authors: Wiley Ronald L. , Zechman Fred W.
Published: December 2017

Respiratory mechanics and diaphragm electromyograms in six anesthetized dogs were studied to determine the immediate nonchemical responses to three levels of added airflow resistance to inspiration. Inspiratory time, intrathoracic pressure amplitude, diaphragm activity, and inspiratory work all increased in the first breath with added resistance. The adjustments to added viscous resistance are interpreted as indicating an immediate active response which tends to maintain an adequate tidal volume. Even though Vt decreased with added resistance, the area under the inspiratory volume curve was unaltered on the first resistance breath. Thus, during the initial response, inspiratory duration may depend primarily upon the accumulated or summated information related to change in volume. Work done on the lung and apparatus was greater with added resistance. The increase resulted from the increased inspiratory time rather than change in rate at which work developed during the inspiration. After two to three breaths on resistance the inspiratory work rate began to increase, probably reflecting the addition of secondary chemical drive.

airflow resistance; diaphragm electromyogram; respiratory control

Submitted on February 14, 1964
Bronchospirometric studies of lung volumes, ventilation/perfusion ratios and diffusion
Authors: Cree E. M. , Rasmussen H. K. , Wright F. , Curtis J. K.
Published: December 2017

Bilateral bronchospirometric nitrogen washout studies were used for the first time to calculate ventilation/perfusion ratios for the well and poorly ventilated areas in individual lungs. Results were compared with washout studies on both lungs measured together. Data suitable for analysis were obtained from seven patients with chronic lung disease. It was demonstrated that this technique for determining simultaneous ventilation/perfusion ratios for each lung gave accurate and detailed physiological changes. Comparison of the sum of average values for pulmonary capillary blood flow when both lungs were measured together by the same nitrogen washout technique showed a variation within the accepted 10% error for cardiac output. Diffusion for the separate lungs, measured by the carbon monoxide breath-holding method, gave values which correlated with lung volumes.

bronchospirometry; nitrogen washout; diffusing capacity

Submitted on November 22, 1963
Hemolysis induced by a Bellofram blood pump; chronic in vitro evaluation
Authors: Liddle Harold V. , Reynolds Harold C. , Carlson Warner W.
Published: December 2017

In the application of extracorporeal pumping systems to chronic assisted circulation, hemolysis may be an important factor. A reciprocating pump utilizing rolling diaphragms has been tested for production of free plasma hemoglobin. In a recirculating system, 1,500 ml of freshly drawn heparinized dog blood was circulated at a flow rate of 3,000 ml/min against pressures of 100, 200, and 300 mm Hg for from 1 to 24 hr. Hemolysis was determined by a modified benzidine method. Recirculation for 1 hr against a height of 142 cm produced 3.6 mg/100 ml, 1.8 mg/100 ml, and 2.4 mg/100 ml free plasma hemoglobin, respectively, for hemolysis indices of 0.001- 0.0013. When the same priming volume was recirculated at 3,000 ml/min and 300 mm Hg pressure for 24 hr, the average hourly rate of free hemoglobin accumulation was 0.5 mg/100 ml, an index of 0.0006. These rates of hemolysis are comparable to the estimated normal human production of free plasma hemoglobin. The extremely low rate of hemolysis produced by this pump is related to the noncompressive action of the rolling diaphragms and flap valves. The characteristics of its performance make this pump ideally suited to chronic perfusion.

extracorporeal pump; assisted circulation; rolling diaphragm; reciprocating pump

Submitted on June 18, 1964
Free fatty acid responses to tilting after water immersion
Authors: Goldman Jack K.
Published: December 2017

Water immersion is accompanied by decreased urinary excretion of noradrenaline and is followed by orthostatic intolerance. The latter has been postulated to result from impaired noradrenaline metabolism. Such an impairment would produce, in addition, a diminished rise in plasma free fatty acids in response to tilting. This response was measured in normals after office control, water immersion and exposure to a thermal environment identical to that found in the immersion facility. The plasma free fatty acid response to a tilt is impaired after water immersion as would be expected if sympathetic nervous system dysfunction is involved in postimmersion orthostatic intolerance.

hypodynamics; orthostatic intolerance; orthostasis sympathetic nervous system; noradrenaline; cathecholamines; simulated o G

Submitted on July 10, 1964
Initial hemodynamic responses to mild exercise in trained dogs
Authors: Smulyan Harold , Cuddy Richard P. , Vincent William A. , Kashemsant Udomporn , Eich Robert H.
Published: December 2017

The transient changes in cardiac output at the onset of mild exercise were measured in dogs trained to walk on a treadmill. Cardiac output was obtained using a krypton 85 infusion method, which permitted frequent determinations of flow. The first go sec of exercise were marked by a prompt rise and overshoot of heart rate and cardiac output, whereas increases in stroke volume occurred later after the onset of exercise, and to a lesser extent than heart rate. At rest, the right atrium was electrically driven at rates slightly faster than heart rates attained spontaneously with exercise and the studies repeated. Changes in cardiac output with exercise were similar to those in unpaced animals, but when the heart rate was fixed stroke volume increased immediately. These studies show a consistent rise in heart rate and cardiac output in the initial reaction to exercise, but when the prompt rise in heart rate was prevented by pacing from the right atrium, increases in stroke volume provided a comparable response in cardiac output.

krypton 85; cardiac output; stroke volume; pacing of heart; oxygen consumption

Submitted on September 23, 1964
A stimulating electrode for nerves
Authors: McCarty Leslie P.
Published: December 2017

A stimulating electrode for nerves and its fabrication are described. The advantages over other types are small size, not easily shorted by conducting solutions, and ease of fabrication.

silicone rubber electrode

Submitted on October 16, 1964
Continuous sampling of arterial blood of unanesthetized animals
Authors: Hamilton Robert W.
Published: December 2017

Implanted arterial catheters permit recording, sampling, and injecting when used in unanesthetized and undisturbed dogs or cats. The catheters are made of silicone rubber tubing fitted to plastic Luer hubs which terminate in resealing rubber serum caps. The catheters are inserted into the descending aorta via the carotid artery and are brought out through the skin on the back of the neck. Results indicate that they can be expected to function for several weeks.

Note:

(With the Technical Assistance of Robert L. Dauber and F. Richard Darrow)

catheters, chronic; catheters, implanted; silicone rubber tubing

Submitted on July 13, 1964
A system for providing surgical anesthesia for germfree rodents
Authors: Carter Darryl , Einheber Albert
Published: December 2017

A system which has been successfully used to provide anesthesia for experimental surgical procedures on germfree rodents within a germfree surgical isolator is described. The preselected air-halothane mixture is sterilized by passage through spun-glass filters. A small Lucite chamber and a nose cone allow induction and maintenance of the halothane anesthesia within the isolator. The system has provided a safe, reproducible anesthesia from which recovery is brief and from which there is no explosion hazard.

germfree animal techniques; halothane anesthesia

Submitted on October 15, 1964
Treadmill for small laboratory animals
Authors: Andrews Robert James
Published: December 2017

A treadmill for exercising small laboratory animals is described. Belt speed can be varied in steps from 13 to 70 ft/min; inclination can be varied from 0 to 160. The apparatus can be locally constructed of surplus laboratory materials and scrap for an estimated cost of $300. It is being satisfactorily used by the Physiology Division of the Naval Medical Field Research Laboratory, Camp Lejeune, North Carolina for biochemical studies utilizing white rats.

small animal exerciser; biochemical studies; metabolism studies

Submitted on August 24, 1964
Short-latency human evoked responses to clicks
Authors: Mast Truman E.
Published: December 2017

The human average evoked response to clicks, recorded from almost any position on the scalp, shows a characteristic short-latency component with its peak at 30 msec. These responses are probably composite, originating partly from muscle and partly from brain. The response recorded from parietal (Pl) to vertex (Cz) differs significantly from a known muscular response from the inion. The 30-msec component from inion is markedly enhanced by contraction of the posterior neck muscles, while that from Pl-Cz is little affected. The two responses differ in their relations of amplitude to stimulus intensity. The Pl-Cz response also differs from temporalis and frontalis muscle responses.

muscle response to clicks; sources of evoked responses

Submitted on October 15, 1964
Storage media for rabbit ova
Authors: Hafez E. S. E.
Published: December 2017

Rabbit ova were stored at 10 or 20 C for 2—14 days. Basic storage media contained: a) 1 or 7% gelatine, b) 7% gelatine and antibiotics, c) 2, 5, or 7% glycerol, d) basic medium but nitrogen atmosphere and storage at 10 or 20C, e) previously frozen serum, f) reconstituted “freeze-dried” serum, g) blastocyst or allantoic fluid, h) egg yolk or egg white, or i) tranquilizer. Stored ova were transferred to appropriate recipients which were laparotomized to measure the implantation rate, then killed to measure embryonic survival. After storage in gelatine media containing 7% gelatine, the rate of implantation was 53% after storage for 7 days and gradually declined until it reached 3% after 14 days of storage. Survival time of ova during storage tended to be prolonged in gelled media, but the addition of antibiotics did not prolong survival time. A concentration of 5% glycerol had no significant effect on ova survival, but the addition of 7% glycerol was deleterious. At 10 C, but not at 20 C, the presence of nitrogen had a deleterious effect on storage of ova. Fresh blood serum could be substituted by: serum previously frozen, reconstituted freeze-dried serum, blastocyst fluid, or egg yolk citrate. Ova did not survive when stored in egg white with Tyrode solution.

embryology; antibiotics; implantation; embryos

Submitted on March 23, 1964
Gradational step tests for assessing work capacity
Authors: Nagle Francis J. , Balke Bruno , Naughton John P.
Published: December 2017

The feasibility of a gradational step test for the assessment of work capacity was investigated. A device was constructed on which the level of a stepping platform could be raised between 2.0 and 50 cm as subjects continued work at a prescribed stepping rate. Two test procedures applicable to individuals who vary in their state of health from that of a chronically ill patient to a trained athlete are described. Sixty men performed experiments to establish the minute-by-minute metabolic costs of the work in the two tests. The oxygen expenditures ranged from 12.9 ± 1.2 to 40.8 ± 3.5 ml/min per kg in the 30/min step test and from 10.7 ± 1.1 to 28.8 ± 1.3 ml/min per kg in the 24/min step test. The procedures are well suited for measuring various physiological parameters during stepping and for establishing physiological working limits. The oxygen costs of the “negative” and “positive” work components in stepping were determined. The cost of negative work was approximately one-third of the positive work. An equation was derived for predicting the metabolic costs of stepping at various rates and platform levels. Comparisons of predicted and measured oxygen intake values for the 30-step and 24-step tests approximated one another at all levels of energy expenditure.

energy expenditure stepping; cardiorespiratory responses to exercise; work in stepping; negative work; positive work; physical fitness tests

Submitted on August 7, 1964
Compliance of the apex of the left ventricle in unanesthetized dogs
Authors: Adolph Robert J.
Published: December 2017

A method has been developed for determining the compliance of the left ventricle of the unanesthetized dog through the chronic sealing of an oncometer to the cardiac apex. The volume of the enclosed apex could be increased by a known amount and the end-diastolic transmural pressure measured. The heart rates of the unanesthetized dogs were slow and the volume of the apex was held constant, hence rate-dependent nonelastic factors were minimized. It is concluded that under the conditions of these experiments, end-diastolic compliance either decreased during infusions of l-epinephrine and angiotensin or did not change. Acetylstrophanthidin administration had no effect on ventricular compliance.

distensibility; elasticity; effects of catecholamines on ventricular compliance; oncometer

Submitted on June 8, 1964
A comparison of two methods for evaluating surface properties of the lung
Authors: Howatt W. F. , Strang L. B.
Published: December 2017

Indices of the surface tension properties of fetal lamb lungs were obtained by the bubble stability method and from direct measurements of a lung extract on a Langmuir-Wilhelmy balance. A comparison of 102 determinations by each method on 31 fetal lamb lungs gave a statistically significant positive correlation coefficient. A comparison of the surface balance index with a pressure-volume deflation index and with gestation and of the bubble stability index with gestation gave statistically significant positive correlation coefficients. Storage by freezing for 21—112 days did not alter either index of surface tension.

lung surface tension; measurement of lung surface tension; surface balance; lung bubbles

Submitted on October 15, 1964
Skin and subcutaneous temperature changes during exposure to intense thermal radiation
Authors: Stolwijk J. A. J. , Hardy J. D.
Published: December 2017

Radiometric measurements have been made of the skin temperature changes occurring during irradiation of the body by high-intensity thermal radiation with square-wave pulses. A quartz lamp bank provided a source of color temperature of 2,650 K and a uniform (± 5%) irradiance of 0.16 cal/sec per cm2 over areas of 40 x 30 cm. A spring-operated focal-plane shutter controlled exposure times from 2–120 sec with a rise time of 0.01 sec. The radiometer, mounted between the quartz lamps so as to view the skin from normal incidence, had a 96% response time of 0.1 sec and a precision of ± 0.1 C. When corrections were made to allow for the far infrared radiation reflected from the skin, the radiometer gave accurate measurements of skin temperature during the periods of irradiation. Experimental values of skin temperature rise were compared with those calculated by the finite differences method for various skin layers using the best available values for optical and thermal properties of each skin layer. During the initial 10–15 sec of irradiation, theoretical and experimental values were in agreement, indicating passive response of the skin to thermal radiation. Subcutaneous temperatures, calculated from surface temperature data, indicated a high degree of penetration of the radiation 0.2–0.4 mm below the skin surface.

mathematical model; infrared reflection by the skin; radiometric measurement of skin temperatures

Submitted on September 2, 1964
Effects of stimulated high altitude on the growth rate of albino guinea pigs
Authors: Delaquerrière-Richardson L. , Forbes Susanna , Valdivia Enrique
Published: December 2017

Two different groups of pregnant albino guinea pigs were exposed continuously, during the second half of gestation, to simulated high altitudes of 12,000 ft in the first experiment and of 14,000–16,500 ft in the second. Pregnancy was significantly shorter in the second experiment than at sea level. Birth weights were lower than in controls in both experiments, more so in the second. Perinatal mortality was markedly increased, reaching 42% in the second experiment. All animals were kept at 12,000 ft after birth. Postnatal growth was slower than at sea level, except in females born at 12,000 ft, whose weights did not vary significantly from those of controls.

hypoxia; perinatal mortality

Submitted on November 10, 1964
Diamine oxidase activity in human maternal and fetal plasma and tissues at parturition
Authors: Southren A. Louis , Kobayashi Yutaka , Brenner Paul , Weingold Allan B.
Published: December 2017

The human maternal-to-fetal plasma diamine oxidase (DAO) ratio was measured in 48 paired samples from full-term pregnancies. A radioassay procedure was employed. The over-all mean maternal-to-fetal (M/F) ratio was 166/1. In a series of 12 premature deliveries the mean M/F ratio was 21/1. The low M/F ratio in the latter group was due to a high mean plasma DAO titer in the premature infants. The relative DAO content of the various trophoblastic and decidual tissues and fluids at parturition in decreasing order of activity, were as follows: decidua = 5,200, membranes = 4,100, placenta = 1,400, amniotic fluid = 100, maternal plasma = 42, cord = 14, and fetal plasma = 1. The accumulated data support the concept of a decidual origin of pregnancy DAO.

radioassay of diamine oxidase; prematurity; trophoblastic and decidual tissues; amniotic fluid

Submitted on September 2, 1964
Indirect determination of maximal O2 consumption in man
Authors: Margaria R. , Aghemo P. , Rovelli E.
Published: December 2017

A nomogram is described for obtaining the value of maximum oxygen consumption per kilogram of body weight from the heart rate values observed at two submaximal work loads. The exercise consists in stepping up and down a 30- to 40-cm bench at a frequency dictated by a metronome. This procedure can be applied to all classes of subjects; the variability of the data obtained is within ±7% with those directly determined.

maximum muscle power; aerobic fitness test for sport

Submitted on January 27, 1965
Continuous duty tonometer system
Authors: Farhi L. E.
Published: December 2017

This tonometer system, for equilibration of blood or other biological fluids, consists of a constant temperature bath which houses four independent tonometer flasks. Temperature stability is maintained by water circulating from the bath into a heating chamber and back. The tonometer flasks rotate continuously and spread the blood in a thin film, exposed to the desired gas mixture, which is prehumidified and flows continuously in and out of the flasks. The advantages of the system are as follows: 1) the temperature within the flasks is maintained to ± 0.01 C from the mean temperature; 2) withdrawal of an equilibrated aliquot does not require stopping the motion of the tonometer; 3) equilibration is rapid in comparison to other methods for the same volume of blood; 4) large amounts of blood can be equilibrated; and, foremost, 5) contamination of the sample with air can easily be avoided.

blood equilibration

Submitted on October 15, 1964
Increase of arterial oxygen tension at altitude by carbonic anhydrase inhibition
Authors: Cain Stephen M. , Dunn James E.
Published: December 2017

Unanesthetized dogs were injected intravenously with 10 mg/kg per 12 hr of the carbonic anhydrase inhibitor, acetazolamide, 24 hr before exposure to a simulated altitude of 21,000 ft (Pb = 335 mm Hg). Arterial blood samples were drawn frequently from a Teflon T cannula surgically placed in a carotid artery 1 or 2 days before the experiment. Arterial Po2, Pco2, pH, lactic, and pyruvic acid concentrations were measured. In comparison with untreated dogs, arterial Po2 at altitude was 9 mm Hg higher, on the average, in treated animals. No physiologically significant accumulation of excess lactate was found. The conclusion was made that carbonic anhydrase inhibition did offer measurable protection, with respect to arterial Po2, against altitude hypoxia and that this protection was achieved at much smaller doses of drug than had been used by other investigators.

hypoxia; altitude protection; excess lactate; lactic acid

Submitted on August 3, 1964
Pattern of blood flow in the pulmonary veins of the dog
Authors: Morkin Eugene , Collins John A. , Goldman Harold S. , Fishman Alfred P.
Published: December 2017

The pattern of blood flow in the large pulmonary veins was studied in dogs by chronic implantation of sine-wave electromagnetic flowmeters and cineangiographic observations. These revealed that: 1) pulmonary venous flow is continuous and pulsatile with peak rate of flow of approximately twice the mean flow; 2) the initial rapid increase in venous flow occurs 0.10 sec after the onset of ventricular systole, reaching a peak at the time of closure of the A-V valves; 3) left atrial contraction produces a fleeting slowing or reversal of flow; and 4) respiratory variations in pulmonary venous flow follow those in pulmonary arterial flow, beat by beat. The genesis of phasic pulmonary venous flow was investigated by analysis of pressure and flow curves from the two sides of the heart, by consideration of the energy required for left ventricular filling, and by reconstruction of the pulmonary venous flow pulse using a mathematical model of the pulmonary circulation. These three lines of evidence are consistent in indicating that the transmitted right ventricular pressure is the major determinant of the pulmonary venous flow pattern in the dog.

pulsatile pulmonary venous flow; pulmonary venous flow; pulmonary circulation; ventricular suction; respiration on pulmonary circulation; pulmonary venous angiography; pulmonary veno-atrial junctions; electromagnetic flowmeter; cineangiography

Submitted on November 16, 1964
Vertical gradient of perfusion in the erect human lung
Authors: Fowler K. T.
Published: December 2017

A quantitation examination is made of a number of mechanisms which might contribute to the gross nonuniformity of blood flow observed in the erect lung. Passive distension of the small vessels by the increased transmural pressures in the base of the lung is shown to be an insufficient explanation of their heightened blood flow. A vertical assemblage of vascular units operating under “waterfall” conditions shows a rapid change of flow per unit with height. These conditions may be caused to apply over a range of heights near the center of the lung by the assumption of critical closing pressures in the capillary bed. If these pressures are allowed to have a range of values in accordance with the anatomical range of capillary diameters the height-flow relationship is brought close to that observed. The expected behavior of a model of this type is discussed.

pulmonary circulation; distensibility of small pulmonary vessels; vertical distribution of pulmonary blood flow; waterfall effect; critical closing pressures in pulmonary circulation

Submitted on August 17, 1964
Effects of cooling the arm and hand
Authors: Petajan Jack H. , Daube Jasper R.
Published: December 2017

This study undertakes to: 1) quantify the effects of immersion of the arm and hand in 10 C water for 15 min on the conduction velocity of the median nerve, the action potential of the thenar muscles, and rapid successive apposing movements (RSM) of the thumb; and 2) determine whether or not habituation by daily 15-min cold exposure of the arm and hand for 5 weeks is reflected in any alteration of the aforementioned parameters. Ten young adult subjects were studied. All parameters of function were grossly impaired by the cooling. A roughly linear dependence upon thenar temperature was found for the latency of response and the duration of the negative spike of the action potential. RSM increased logarithmically with increasing thenar temperature. In two repeatedly exposed subjects, RSM improved slightly under all conditions which was felt due to learning. More frequent cyclic vasodilatation and more rapid finger tip warming was observed. No significant difference in conduction velocity between control and habituated subjects was found.

cold effects; muscle contraction; habituation; cyclic vasodilatation; nerve conduction; action potential

Submitted on December 9, 1964
Effects of an intragastric balloon on gastric pressures in man
Authors: Stunkard Albert J. , Reinhard Arthur
Published: December 2017

The influence of an intragastric balloon in the fundus on intragastric pressure changes was assessed by comparing the intragastric pressures measured by an open-tipped catheter proximal to the balloon when the balloon was inflated and when it was not. Six subjects were tested, each twice with the balloon inflated and twice with it deflated. Two significant differences were found when the balloon was inflated: 1) periods of pressure elevations were present more of the time and 2) the waveforms generated were of greater amplitude and shorter duration. The balloon thus appears to have exerted a definite but limited effect upon gastric motility. A method for analyzing the difference in waveforms is described. Both the balloon and the open-tipped catheter recorded gastric pressure elevations which frequently occurred at the same time and were of comparable magnitude. Often, however, balloon-recorded elevations occurred in the absence of catheter-recorded ones and vice versa.

effects of gastric balloon; waveform analysis

Submitted on September 28, 1964
Comparison of screen filtration pressure and low-shear viscosity of blood
Authors: Gregersen Magnus I. , Usami Shunichi , Chien Shu , Swank Roy L.
Published: December 2017

Screen filtration pressure (SFP) and blood viscosity (at shear rates of 0.05 sec-1 and 5 sec-1) were determined simultaneously on dog blood. Addition of high molecular weight dextran (250,000) caused increases in both viscosity and SFP, and the latter showed a plateau during the 10-sec period of measurement. When 5-hydroxytryptamine together with adenosine diphosphate were added to blood and when blood was obtained after severe hemorrhage, viscosity did not change but SFP increased sharply and showed no tendency to approach a steady state. Such sharp increases in SFP were not observed when the experiments were performed on blood without buffy coat. It is concluded that SFP of blood containing high molecular weight dextran reflects viscosity at relatively high shear rates and that the sharp increases in SFP following the addition of 5-hydroxytryptamine and adenosine diphosphate as well as following exsanguination are due to the adhesiveness of platelets and/or leucocytes to the screen.

Note:

(With the Technical Assistance of Kathleen Prichard)

adenosine diphosphate; dextran; hemorrhage; 5-hydroxytryptamine

Submitted on January 8, 1965
Total respiratory compliance in infants and children
Authors: Sharp J. T. , Druz W. S. , Balagot R. C. , Bandelin V. R. , Danon J.
Published: December 2017

Page 775: J. T. Sharp, W T. S. Druz, R. C. Balagot, V. R. Bandelin, and J. Danon. “Total respiratory compliance in infants and children.” In Fig. 7, upper left-hand corner, the equation should read: Ct20 = 3.95 x Ht2.35 x 10–4.
Effect of muscle constriction on flow-limiting collapse of isolated canine trachea
Authors: Knudson R. J. , Knudson D. E.
Published: December 2017

Before and after trachealis muscle contraction, induced by application of acetylcholine, the relationship of changing pressures to flow through excised canine tracheas was examined in a mechanical model simulating isovolume pressure-flow relationships in vivo. At the same time, the change in cross-sectional lumen area at a point in the downstream third of the trachea was measured using slit-lamp transillumination and cinematographic measurements. Trachealis muscle contraction reduced the uncompressed lumen area but inhibited dynamic collapse as driving pressures increased. As a result, following contraction, the initial slope of the tracheal pressure-flow (TPF) curve changed, indicating increase in resistance at low flows, but higher flows were achieved at higher driving pressures. Results suggest that smooth muscle tone of large airways may affect maximum expiratory flow (Vmax) and explain apparent discrepancies between in vivo measurements of resistance and Vmax. The magnitude of the Bernoulli effect contributing to airway narrowing was demonstrated by measurements of lateral airway pressures well in excess of driving pressure.
Lung volume and interdependence in the pig
Authors: Sylvester J. T. , Menkes H. A. , Stitik F.
Published: December 2017

The effect of lung volume on the mechanical interdependence between an obstructed sublobar region of lung and its surrounding tissues was investigated in intact and isolated pig lungs. Interdependence is arbitrarily defined as the effectiveness with which the linkage between the region and surrounding tissue mediates a tendency for inflation to become even whenever it is uneven. We found that when the volume of the surrounding lung (Vl) was high relative to the volume of the obstructed region (Vr), or when they were relatively equal at higher inflation states, interdependence decreased. When Vr was high relative changes in regional shape observed during even and uneven inflation states, we suggest that regional distortion and its effects on regional elastic recoil are important determinants of pulmonary interdependence.
Tolerance to unilateral or bilateral ischemic hand exercise
Authors: Rodbard S. , Sarzana D.
Published: December 2017

During tourniquet occlusion of blood flow in 10 volunteers, the number of contractions performed by each arm contracting simultaneously with the other, equalled or exceeded the number of contractions performed by either arm alone. The discomfort produced by ischemic muscle exercise is interpreted in terms of the most dominant stimulus, and impulses appear not to summate.