bluuebunny/crossref_metadata_2025 huggingface dataset:
Metabolism and the protection by anesthesia against toxicity of O2 at high pressure
Authors: Bean John W. , Zee Dominic
Published: December 2017

Experiments were performed on rats to determine whether the protection which anesthesia (sodium pentobarbital) affords against convulsions in oxygen at high pressure (OHP) of 70–75 psi extends to the pulmonary damage and, if so, whether such protection is due simply to the depression of general metabolism. These experiments showed that anesthesia protected against both the pulmonary damage and the convulsions and that this protection was equally well pronounced whether the metabolic depression was or was not counteracted and elevated by dinitrophenol, L-thyronine, or direct tetanic stimulation of muscle. The results support the conclusion that such protection is not due simply to the depression of general metabolism as has been claimed. They also imply that the potentiation of pulmonary damage in OHP by thyroid and CO2 is not a direct effect but rather is of central origin. The close association between the pulmonary damage and convulsions in OHP justifies the inference that these effects are not separate entities, as has been claimed, and point to the importance of central and neurogenic factors in the causation of this pulmonary damage.

hyperbaric oxygenation; oxygen poisoning at high pressure; oxygen convulsion in relation to pulmonary damage; pulmonary edema and congestion in oxygen at high pressure; neurogenic factors and toxicity of oxygen at high pressure; direct and neurogenic effects of oxygen at high pressure on the lungs; pCO2and oxygen poisoning; thyroid and pulmonary damage in oxygen poisoning; protection against oxygen toxicity by pentobarbital, urethan, alpha chloralose, and propylene glycol

Submitted on September 11, 1964
Impedance measurement of tidal volume and ventilation
Authors: Hamilton L. H. , Beard J. D. , Kory R. C.
Published: December 2017

Thoracic impedance changes have been used to measure tidal volume and ventilation in normal subjects. Tidal volume was measured directly and total ventilation was accumulated with a diode voltage pump. The size, shape, and placement of the electrodes affected the reliability with which the system measured ventilation. A high correlation was demonstrated between transthoracic resistance or capacitance changes and ventilation when special narrow ridged electrodes were applied bilaterally on the thorax. The variability between accumulated impedance changes and ventilation measured with a spirometer had a standard deviation less than ±6% of the ventilation. A linear relationship was demonstrated between lung volume change and impedance change for subjects in the standing, sitting, or supine positions, whether the breathing pattern was normal, predominantly thoracic, or predominantly abdominal.

transthoracic impedance; tissue resistance; tissue capacitance

Submitted on June 24, 1964
Dipalmitoyl lecithin: studies on surface properties
Authors: Kuenzig Marian C. , Hamilton Robert W. , Peltier Leonard F.
Published: December 2017

A preparation of synthetic dipalmitoyl lecithin has been devised whose activity on a Wilhelmy surface balance is similar to that of extracts from normal lungs. An ethanol solution of lecithin is precipitated with albumin, and a drop of the suspension containing approximately 0.04 mg lecithin is spread on the surface of 0.9% NaCl in the trough of the balance. This preparation appears to be insensitive to oxidation and when run under humidified air gives reproducible results. It has a low minimum surface tension (5—10 dynes/cm) when compressed to 20% of the original surface area and exhibits considerable hysteresis on re-expansion. Addition of certain lipids to the surface film produces changes similar to those caused by addition of these lipids to cat lung extracts.

surface tension; surface activity; pulmonary surfactant

Submitted on September 8, 1964
Resistivity of flowing salt solutions
Authors: McFee Richard , Spatuzzi Anthony R.
Published: December 2017

The longitudinal resistance of salt solutions flowing in rigid tubes is found to change by less than frac14 of 1% for flow velocities up to and exceeding the turbulent rate. The reduced resistance of flowing blood as contrasted to stationary blood is thus not due to altered resistance of the fluid proper

rheoencephalogram; blood flow; impedance; plethysmography

Submitted on November 3, 1964
Normal respiratory and circulatory values in the cat
Authors: Nadeau R. A. , Colebatch H. J. H.
Published: December 2017

Seventeen cats were studied under chloralose anesthesia. In 6 cats a polyethylene catheter was placed in the main pulmonary artery via the external jugular vein. In 11 other cats, a right thoracotomy was done under artificial ventilation, and small nylon catheters were inserted into the main pulmonary artery and the left atrium via the vessels of the right upper lobe, after which the chest was closed. While the animal breathed air through a closed circuit with a constant supply of oxygen, respiratory rate, tidal volume, and oxygen consumption were recorded on a smoked drum. Oxygen consumption averaged 111.4 ± 28.9 ml/min per m2. Femoral arterial and pulmonary arterial blood oxygen contents were measured by a modification of the Barcroft-Haldane method with Warburg manometers and averaged 14.18 ± 3.68 and 9.36 ± 1.39 vol %, respectively. The cardiac output was measured according to the Fick principle and averaged 2.10±.70 liters/min per m2. Heart rate, femoral artery blood pressure, pulmonary artery blood pressure, left atrial pressure, end-expiratory pleural pressure, and femoral artery blood oxygen tension were also determined. No significant difference was noted between thoracotomized and intact cats. Cardiac output values, however, were significantly greater than those previously reported for this species.

oxygen consumption; cardiac output

Submitted on October 8, 1964
Effect of oxygen breathing at atmospheric pressure on pulmonary surfactant
Authors: Giammona Samuel T. , Kerner Donald , Bondurant Stuart
Published: December 2017

To evaluate the effects of oxygen breathing at atmospheric pressure on pulmonary surfactant, cats, rabbits, and rats were continuously kept in 98% oxygen until death occurred. Pulmonary surfactant was extracted by mincing of the lung and by foam fractionation of the lung. Surface tension of the extracts was measured on a Wilhelmy balance. Lung extracts prepared by both methods from the cats and rabbits kept in oxygen had greater surface tension than lung extracts from control animals. Surface tension of extracts prepared by foam fractionation of lungs of rats kept in oxygen did not differ from that of extracts of lungs of control rats, whereas surface tension of extracts prepared by mincing lungs of rats kept in oxygen had minimum surface tension greater than that of lung extracts of control rats. This species difference in the effects of oxygen breathing on pulmonary surfactant may reflect a difference in the pathogenesis of oxygen intoxication.

oxygen intoxication; surface tension

Submitted on October 19, 1964
Concept and measurement of ventilatory sensitivity to carbon dioxide
Authors: Dejours P. , Puccinelli R. , Armand J. , Dicharry M.
Published: December 2017

Four resting subjects breathed 0, 1, 2.5, and 4% CO2 diluted in air for 25 min. Ventilation, Po2 and Pco2 of alveolar and expired gases were measured. One can represent on a Po2-Pco2 diagram, as Rahn and Fenn have done, some features of the reaction to CO2, and plot lines of “ventilatory isosensitivity to CO2.” The relation between experimental points and these lines shows why “ventilatory CO2 sensitivity,“ DeltaVa/DeltaPaCOCO2, for normal conditions cannot be quantified by the classical procedure of giving one or several percent CO2 to breathe. CO2 sensitivity nonetheless exists normally, since in subjects breathing mixtures containing a few mm Hg CO2, PaCOCO2 is practically unchanged, while PaOO2 rises by several mm Hg. The difficulties of accurately measuring DeltaVa/DeltaPaCOCO2 suggest caution in accepting some mathematical developments often applied to raw data, and in taking this ratio as a true index of ventilatory CO2 sensitivity, particularly when measurements made with high inspired CO2 concentration are used to interpret the regulation of normal respiration.

alveolar pathway during CO2 breathing; control of breathing; hypercapnia; O2-CO2 diagram

Submitted on December 11, 1964
Effects of compression on composition and absorption of tissue gas pockets
Authors: Van Liew Hugh D. , Bishop Beverly , D. Pio Walder , Rahn Hermann
Published: December 2017

Data with subcutaneous gas pockets in rats and theoretical considerations lead to the following conclusions concerning the effects of compression on preformed gas bubbles in the body: 1) Besides mechanically decreasing bubble size, compression causes an additional volume decrease due to readjustment of water vapor, CO2 and O2 volumes in the bubble. 2) The pocket-to-tissue Pn2 difference (in the stabilized condition in which tissue Pn2 equals arterial Pn2) is almost completely dependent on alveolar oxygen, not on compression per se. Compression with air elevates alveolar O2, but the same nitrogen difference could be gained by inhaling oxygen-enriched gas at lower pressures. 3) Compression causes an increased pocket-to-tissue Pn2 difference which hastens N2 absorption, but at the same time decreases surface area and thus tends to slow absorption.

hyperbaric; oxygen; decompression sickness; gas bubbles; high pressure

Submitted on October 26, 1964
Initiation of sweating in man after abrupt rise in environmental temperature
Authors: Colin Jean , Houdas Yvon
Published: December 2017

In 38 experiments a total of eight men were subjected, after a long waiting period in a neutral environment, to an abrupt rise in environmental temperature. Skin, rectal, oral, and tympanic temperatures, and weight loss were continuously recorded. Two types of responses were seen: a) nonadapted subjects presented a delay in the onset of sweating, with a good correlation between this onset and rise in rectal or tympanic temperature, but without correlation with rise in skin temperature; b) adapted subjects presented an immediate onset of sweating without correlation with rectal temperature, and a second acceleration of sweating corresponding to the rise of rectal temperature. It is concluded that for nonadapted subjects the mechanism of sweating is activated by centrally located receptors, but that in adapted subjects, skin receptors are able to activate the sweating mechanism before central receptors feed their impulses to the heat loss center.

rapid rise in temperature; adaptation to warmth; skin, rectal, and tympanic temperatures; adjustable set point; heat loss in man

Submitted on August 17, 1964
Development of a criterion for physical fitness tests from factor analysis results
Authors: Ismail A. H. , Falls H. B. , MacLeod D. F.
Published: December 2017

The purpose of the study is twofold: 1) to illustrate a method whereby it is possible to combine the various criteria for physical fitness to form one composite criterion and 2) to develop physical fitness test batteries. As a result, a method for combining the various criteria of physical fitness tests into one composite criterion was described. Furthermore, physical fitness test batteries were developed.

work capacity—assessment from single criterion; exercise tolerance—factor analysis; composite fitness score

Submitted on July 10, 1964
Effect of acceleration on the distribution of pulmonary blood flow
Authors: Bryan A. C. , Macnamara W. D. , Simpson J. , Wagner H. N.
Published: December 2017

The distribution of pulmonary blood flow has been measured during increased positive (+Gz) acceleration. Macroaggregated albumin labeled with iodine 131 was injected intravenously during centrifugal acceleration, by the method described by Wagner and co-workers. The particles embolize the pulmonary vascular bed in proportion to flow and can be subsequently detected by scintillation scanning of the lung. One study was done in one subject in one of the five following conditions: supine, seated, +2 Gz, +3 Gz, and +4 Gz. The results show a progressively smaller reduction in upper zone perfusion with increasing acceleration agreeing with hydrostatic principles. Flow increased in the base up to +2 Gz but thereafter becomes fixed, suggesting that the vessels were then maximally dilated. The gas exchange consequences of these changes of perfusion are discussed indicating that there must also be ventilatory changes.

lung; perfusion; iodine 131; acceleration

Submitted on January 18, 1965
Precooling of peripheral arterial blood in cold-adapted and warm-adapted rabbits
Authors: Honda Nishio
Published: December 2017

The role of precooling of peripheral arterial blood in temperature regulation has been studied in cold-adapted and warm-adapted rabbits. It was found that precooling of arterial blood during its flow from the interior to the surface (ear) of the body in a cold environment is more marked in the cold-adapted rabbits than in warm-adapted rabbits. In a warm environment no difference was found between the two groups.

countercurrent heat exchange; cold adaptation or acclimation

Submitted on February 8, 1965
Effect of a transient displacement of blood toward the heart on the pulse rate
Authors: Walker Roger L. , Mackay Ian F. S.
Published: December 2017

Sudden release of venous congesting cuffs in human subjects may cause a tachycardia. Among the factors that may be responsible for this increase in heart rate are a) a fall in arterial pressure, b) the hyperpnea that follows the cuff release, and c) an increase in “venous return.” A technique was designed which excluded the first two of these factors and, under the conditions of this technique, a demonstrable transient displacement of blood toward the heart with an associated rise in venous pressure but no change in arterial pressure did not cause cardiac acceleration. The presence of a “Bainbridge” type of reflex in man is questioned.

Bainbridge reflex; cardiac reflexes in man; right heart filling

Submitted on September 28, 1964
Static features of the passive rib cage and abdomen-diaphragm
Authors: Agostoni Emilio , Mognoni Piero , Torri Giorgio , Agostoni Ada Ferrario
Published: December 2017

The static relation between lung volume and rib cage circumference has been determined over the vital capacity range, during relaxation and activity of the respiratory muscles with open airway. At small volume the circumference is larger during relaxation; the reverse occurs at large volume. During relaxation at full expiration the cross section of the rib cage becomes more elliptical and in some subjects also greater. Hence the shape of the chest wall during muscular activity is different from that during relaxation. Because of this change of chest wall shape the outward recoil of the passive rib cage at full expiration, in the seven subjects examined, is higher than that given by the conventional volume-pressure curve during relaxation. The volume displacements of the rib cage and of the abdomen-diaphragm have been calculated and the volume-pressure curves of the passive rib cage and abdomen-diaphragm have been constructed, taking into account the changes of the chest wall shape occurring during relaxation.

change of chest wall shape during relaxation; relation between lung volume and rib cage circumference during relaxation; relation between pleural pressure and rib cage circumference during relaxation; recoil of the passive rib cage; pressure exerted by the expiratory muscles at full expiration; volume-pressure curve of the passive rib cage; volume-pressure curve of the passive abdomen-diaphragm

Submitted on September 14, 1964
Effects of forward acceleration on anatomical dead space
Authors: Jacquemin Charles , Demange Jean , Timbal Jean , Varene Pierre
Published: December 2017

The effects of transverse acceleration (1–5 G) on anatomical dead space have been studied on four human subjects. Instantaneous analysis of expired gases has been done by mass spectrometer. Half deflection between inspired gases and alveolar plateau levels is considered as the signal for the end of dead-space sweep. It is confirmed that no obstructive syndrome occurs during these accelerations. The airway size is not reduced; on the contrary, the anatomical dead space increases with the level of accelerations. Furthermore, a decreasing slope of the CO2 alveolar plateau has been noted on two subjects. These facts can be interpreted admitting a passive displacement of the pulmonary blood mass under influence of forward acceleration and the adjustment of ventilation to perfusion.

transverse acceleration; mass spectrometer; ventilation-perfusion ratio

Submitted on February 8, 1965
Adrenergic effects in splenic pO2 of rats in air or oxygen at 5 atmospheres
Authors: Jamieson Dana
Published: December 2017

Oxygen tensions have been measured in the spleens of rats breathing air and during exposure of the animals to 5 atm abs of oxygen (HPO). The response of splenic pO2 to compression was complex, usually reaching a peak value immediately after compression, then falling to a lower value. This form of response has been termed a hump response. After adrenalectomy or bretylium tosylate injection the hump response of pO2 after compression was almost abolished, and the values of splenic pO2 at 5 atm were considerably higher than in control animals. A combination of adrenalectomy and bretylium tosylate also markedly reduced the number of hump responses, but unexpectedly significantly lowered splenic oxygen tensions, both when the animals were under ambient conditions or at 5 atm of oxygen. Cardiac rate and blood pressure were studied in an attempt to find the explanation of this latter effect, and while blood pressure was the same in adrenalectomized rats and control rats after bretylium injection, adrenalectomy potentiated the bradycardia produced by bretylium tosylate.

bretylium tosylate; compression in oxygen; cardiac rate; adrenalectomy; blood pressure

Submitted on September 21, 1964
Morphological changes in avian eggs subjected to accelerative force
Authors: Besch E. L. , Smith A. H. , Walker M. W.
Published: December 2017

Subacute accelerative forces cause a yolk particle displacement (apparent on the yolk surface) which erodes the blastoderm cells and results in reduced hatchability. The disturbance of the yolk substance is slowly induced, proportional to the force intensity, and its degree directly related to reduced hatchability. There is no apparent effect of the accelerative force on the vitelline membrane which surrounds the yolk. Impact deceleration does not cause an apparent morphological or biological change in the blastoderm.

yolk particle displacement; blastoderm alteration; egg yolk structure; hatchability; impact deceleration; centrifugal force

Submitted on December 31, 1964
Effect of immersion on intrapulmonary pressure
Authors: Jarrett A. S.
Published: December 2017

Pressure-volume relaxation curves have been determined for relaxed, breath-holding subjects lying and sitting in air and water. Immersion in water resulted in a marked increase in intrapulmonary pressure, the whole pressure-volume curve appearing to be shifted along the pressure axis. From the regression equations of the four curves the pressures at normal relaxed chest volume were calculated, and the center of pressure of the immersed chest shown to lie 19 cm below and 7 cm behind the sternal angle. The significance of this to the positioning of a diver's demand valve is discussed.

center of pressure of thorax; immersion and chest volume; eupneic pressure; diving physiology; underwater respiration

Submitted on September 10, 1964
Effect of repetition on the energy expenditure of women performing selected activities
Authors: Richardson Martha
Published: December 2017

Twenty-one typical homemaking tasks were performed by physiologically “normal” women 2–6 times/day, several days per week. Results from these studies are appraised from the standpoint of the possible “learning” effects of repeated performance of the same task. Energy expenditures for sitting and standing quietly and for 8 of 21 activities showed no significant decrease with a repetition of trials, presumably because the work conditions were already familiar to the subjects. For 13 of the activities, significant decreases in energy expenditure resulted with increasing number of times the task was performed, and the negative relationships were plotted. Rates of decrease appeared to vary according to the type of basic component movements involved in each task, e.g., manipulatory as compared with travel components. Data from studies of 8 of the 13 tasks were fitted by quadratic and quartic curves, an indication of interruptions in the effects of repetition.

work

Submitted on March 19, 1965
Modifications of the portacaval shunt in the rat
Authors: Kennan A. L.
Published: December 2017

Two refinements of the end-to-side portacaval anastomosis in the rat, the superior mesenteric-caval and the splenocaval, have been presented along with a continuous-suture method which makes possible a more rapid surgical procedure. Rats have been maintained with these shunts for 6 months after which autopsies have shown the shunts to be patent. The superior mesentericcaval anastomosis offers a unique system for examining the influence of dietary products on the liver. The diversion of insulin in the splenocaval anastomosis may provide a liver condition more nearly like that of the diabetic patient than those experimental systems previously used. Both shunts are being utilized in this laboratory for further study of liver systems.

liver function; suture methods

Submitted on January 27, 1965
A rate signal interpreter
Authors: Partridge Lloyd D. , Jones Richard F.
Published: December 2017

Page 543: Partridge, L. D., and R. F. Jones, “A rate signal interpreter.” The diodes in Fig. 2 should be labeled 5A6.
Determination of human body volume from height weight
Authors: Sendroy J. , Collison H. A.
Published: December 2017

Page 167: Sendroy, J., Jr., and H. A. Collison, “Determination of human body volume from height weight” In footnote 1O (p. 171), reference 7 should be reference 17.
Quantitation of collagen in the wall of the human urinary bladder
Authors: Swaiman Kenneth F. , Bradley William E.
Published: December 2017

Clinicians visually assess skeletal muscle atrophy and by clinical testing evaluate muscle weakness. Similar direct assessment of muscle function is not applicable to the detrusor muscle of the urinary bladder. The slow fill cystometrogram is useful in detecting reflex abnormalities and the physical state of the bladder wall but does not quantitate muscle loss and fibrotic replacement (10). Diagnostic aid may be obtained by histologic examination of detrusor muscle biopsies. However, neither of these techniques measure smooth muscle depletion and collagen replacement secondary to neurologic vesical dysfunction and its sequelae of inflammation and fibrosis (2).
Energy cost of Piloting fixed- and rotary-wing aircraft
Authors: Littell D. E. , Joy R. J. T.
Published: December 2017

The energy cost of piloting three US Army helicopters (light, utility, and medium) and one utility fixed-wing aircraft was investigated. Energy expenditure was calculated from expired minute volume and expired air oxygen content measured during the basal state and in normal flight conditions. Data were collected on a total of 16 pilots, 5 of whom flew all three helicopters. All of the helicopter pilots were experienced test pilots. The data indicate that, for these pilots, and flying conditions studied (level flight in good weather) and aircraft, the energy cost must be classed as very light work, averaging 1.79 kcal/min. The energy cost of flying the fixed-wing aircraft by less experienced pilots was similar to previously reported energy expenditures for such aircraft. The data were segregated to separate measurements made at altitude from those made during flight in close proximity to the ground (take off, hover, etc). In three of the four aircraft, the pilot's energy expenditure was greater when ground contact was possible.

flying; energy expenditure; work fatigue; helicopters; bioenergetics; oxygen consumption; military medicine

Submitted on August 12, 1968
Arterial chemoreceptor oxygen utilization and oxygen tension
Authors: Edwards M. W. , Mills E.
Published: December 2017

(See PDF)
Chemosensitivity in normal subjects, athletes, and patients with chronic airways obstruction
Authors: Godfrey Simon , Edwards Richard H. T. , Copland Grahame M. , Gross Peter L.
Published: December 2017

Studies of CO2 and O2 sensitivity have been made using rebreathing methods in normal subjects, athletes, and patients with and without chronic airways obstruction. The rebreathing techniques enabled isoxic CO2 response curves and isocapnic O2 response curves to be constructed from many points obtained over a short time. There was little difference in response among the groups of normal subjects but the patients with lung disease had a flatter CO2 response curve and required lower levels of Po2 to stimulate ventilation. When ventilation was expressed as a fraction of the maximal voluntary ventilation, much of the difference between normal subjects and chest patients disappeared, suggesting that the reduced ventilatory response may be of mechanical origin. There remained some patients who were truly insensitive to one or both stimuli and they appeared to be those whose clinical condition was poorest.

rebreathing techniques; isoxic CO2 sensitivity; isocapnic O2 sensitivity; relation to ventilatory capacity; insensitivity of some patients
Early changes in lungs of rats exposed to 70 per cent O2
Authors: Redding R. A. , Arai T. , Douglas W. H. , Tsurutani H. , Overs J.
Published: December 2017

Sixty-six respiratory disease-free rats, divided into four groups, were exposed to 70% O2 for 1.5, 4, 7, and 10 days and compared with 31 littermates exposed to room air for equal times. Lung surfactant was separated from macrophages and potential serum protein contamination by differential centrifugation of endobronchial washings. In the O2-exposed rats, developing lung edema was demonstrated by decreased dried/fresh lung weight ratio and increased alveolar protein content at 7 and 10 days. At 7 days, lung compliance slope and hysteresis loop area decreased, while critical opening pressure increased. Ultrastructurally, the only abnormality seen was an irregular widening of the alveolar capillary basement membrane on day 10. Alveolar lecithin content decreased slightly during the 10 days exposure, but remained highly saturated, whereas whole lung lecithin content increased. These results suggest that the initial mechanical and morphological alterations in rats exposed to 70% O2 are related to lung edema and are not dependent upon lung surfactant alterations.
Respiratory gas exchange ratio and prediction of aerobic power
Authors: Shephard R. J.
Published: December 2017

The Issekutz procedure for the prediction of maximum oxygen intake from the respiratory exchange ratio (R) has been evaluated on a diverse group of 308 subjects, including “whites” and Eskimos, men and women ranging in age from 16 to 65 yr. When applied to young white men performing 12 min of progressive step or treadmill exercise, the prediction procedure has a coefficient of variation of less than 10%, without systematic error. Unfortunately, the standard equation lacks generality, and erroneous predictions can arise from a change of test protocol, the use of a different exercise modality, or application to older subjects. If a brief exercise format is used, low R values may be reported during an early phase of relative hypoventilation. At a given metabolic loading, bicycle ergometry yields a higher respiratory minute volume than other modes of exercise. A heavy loading of one muscle group seems responsible, and the results is a high R value in submaximum effort. Aging is associated with a lowering of maximum blood lactate levels and thus maximum figures for R.
Influence of body position on pulmonary diffusing capacity in yound and old men
Authors: Sundstrom G.
Published: December 2017

Steady-state diffusing capacity (DLCOSS2), studied in healthy nonsmokers, was significantly higher in five old men when seated than when supine, but was unchanged in five young men. However, “corrected” for the increased ventilation, it decreased in the young--but not in the old--when erect compared with when supine. The change of DLCOSS2 in the young during the first 20 min when seated was related to a change of the fractional dead space ventilation (VD/VT)mThe old showed less venous admixture when seated than when supine, whereas VD/VT and regional ventilation-perfusion index of the lung bases was the same in both positions. The decrease in venous admixture was probably due to the closing capacity (CC) being less than the functional residual capacity (FRC) when seated. The elimination of closed off regions when seated made more pulmonary capillaries available for diffusion.
Simulation of frequency dependence of compliance and resistance in healthy man
Authors: Bobbaers H. , Clement J. , Pardaens J. , Woestijne K. P.
Published: December 2017

The frequency dependence of effective compliance, Ceff, and resistance, Reff, are reproduced by means of a two- or four-compartment linear mathematical model with pleural pressure as a sinusoidal input. The model simulates the mechanical properties of lung parenchyma, alveolar gas, bronchial wall, and cheeks, as well as the distribution of gaseous resistances and inertances within the airways. Values, representative for a young healthy adult, are assigned to these various parametersmit appears from this study: 1) that the gas inertance produces a very marked increase of Ceff, noticeable already below 1 cycle/smto obtain a frequency independence of Ceff between 0 and 2 cycles/s, it is necessary to introduce a marked inhomogeneity in the model. 2) Such an inhomogeneity is realized by simulating a pleural pressure difference of 6 cmH2O between the compartments of the bialveolar model. It can be shown that this corresponds to a total pleural pressure difference of about 9 cmH2O in a model consisting of an infinite number of compartments. 3) The influence of the compressibility of alveolar gas and of mechanical properties of the bronchial wall and of the cheeks on Ceff and Reff is small or negligible.
Frequency and duration of interval training programs and changes in aerobic power
Authors: Fox E. L. , Bartels R. L. , Billings C. E. , O'Brien R. , Bason R. , Mathews D. K.
Published: December 2017

This study was designed to ascertain whether 7- and 13-wk interval training programs with training frequencies of 2 days/wk would produce improvement in maximal aerobic power (VO2max) comparable to that obtained from 7- and 13-wk programs of the same intensity consisting of 4 training days/wk. Sixty-nine young healthy college males were used as subjects. After training, there was a significant increase in VO2max (bicycle ergometer, open-circuit spirometry) that was independent of both training frequency and duration. However, there was a trend for greater gains after 13 wk. Maximal heart rate (direct lead ECG) was significantly decreased following training, being independent of both training frequency and duration. Submaximal VO2 did not change with training but submaximal heart rate decreased significantly with greater decreases the more frequent and longer the training. Within the limitations of this study, these results indicate that: 1) maximal stroke volume and/or maximal avO2 difference, principle determinants of VO2max, are not dependent on training frequency nor training duration, and 2) one benefit of more frequent and longer duration interval training is less circulatory stress as evidenced by decreased heart rate, during submaximal exercise.
Interrelations between pulmonary liquid volumes and lung compliance
Authors: Hauge A. , Bo G. , Waaler B. A.
Published: December 2017

We have investigated the relative effects of lung edema and of increases in pulmonary blood volume (PBV) on lung compliance (CL), and also the effects of selective elevations of pulmonary arterial (Ppa) and left atrial (Pla) pressures on PBV and on CL, using an isolated, perfused, and ventilated rabbit lung preparation. Lung weight was continuously recorded. A step rise in Pla at constant flow caused a rapid rise in PBV accompanied by an immediate fall in CL. With maintained high vascular pressures interstitial edema accumulated with no further fall in CL. Not until 3 times the normal amount of extra-vascular fluid had accumulated did a further, secondary reduction in CL occur. When Ppa was elevated to the same level by 1) a rise in flow and 2) a rise in Pla, the latter type of experiment gave 3–5 times larger increases in PBV. Pla elevations with or without rise in Ppa (flow adjusted) gave almost the same rises in PBV. The fall in CL was related to rises in PBV regardless of how such rises were obtained. Our conclusion is that increases in PBV, but not accumulation of interstitial edema, reduced CL in this preparation.
Control of vascular volume in sheep umbilical circulation
Authors: Bissonnette J. M.
Published: December 2017

Vascular and extravascular volumes were measured using a single-injection, double-indicator technique, in a perfused umbilical circulation in which umbilical artery (Pfa) and umbilical vein (Pfv) pressures could be independently varied. At constant Pfv, when Pfa was raised from 25 to 35 mmHg, vascular volume increased 16.1 plus or minus 6 ml (mean plus or minus SD) from a control value of 113 plus or minus 38.3 ml. Extravascular volume increased 25.2 plus or minus 7.7 ml from 128 plus or minus 53.3 ml. During further increases in Pfa to 65 mmHg, vascular volume increased approximately 10 ml for each 10 mm Hg increment, but no change in extravascular volume occurred. At a constant Pfa when Pfv was raised to 15, 20, and 25 mmHg, vascular volume increased 12.2 plus or minus 3.6, 22.2 plus or minus 5.4, and 28 plus or minus 12.5 ml from the measurements at low Pfv. There was no increase in extravascular volume during elevation of Pfv. At the lower values of Pfa (25–35 mmHg) recruitment of previously unperfused channels and distension are seen. Over the higher ranges of Pfa change and during Pfv elevation there is distension of vascular bed.
Relationship between turnover rate and blood concentration of lactate in exercising dogs
Authors: Eldridge F. L.
Published: December 2017

Steady-state blood lactate concentrationss and lactate turnover, or entry, rates were determined by use of constant infusion of L(+)-[14C]lactate in seven anesthetized dogs before and during electrically induced exercise. Lactate entry rates increased during exercise in all dogs with or without the infusion of additional exogenous cold lactate. Blood lactate concentrations, on the other hand, rose to levels considerably below those predicted for these entry rates in a previous study of the relationship in normal nonexercising dogs. It is concluded that improved efficiency of lactate removal during exercise allows low blood concentrations despite large increases in entry rates.
Cardiac limitation to maximal oxygen transport and changes in components after jogging across the US
Authors: Bruce R. A. , Kusumi F. , Culver B. H. , Butler J.
Published: December 2017

Observations were made before and 3–5 days after prolonged endurance jogging an average of 42 miles/day, 6 days/wk for 2.5 mo by a young male adult who voluntarily initiated a run across the United States. Both arterial PO2 and lactic acid increased. In each instance, the first limitation in circulatory delivery of oxygen was a plateau in stroke volume and cardiac output. Afterward, pulse deficit and systemic arterial pressure fell with exercise and heart rate accelerated. Although there was no change in oxygen transport (Q X CAO2), a reduction in stroke volume was exactly balanced by a rise in arterial oxygen content. Vital capacity, residual volume, and total lung capacity and diffusion capacity for carbon monoxide, hematocrit, and red cell mass increased, while plasma volume diminished and heart size and total blood volume were unchanged.
Validation of an automated determination of pulmonary resistance by electrical subtraction
Authors: Drazen J. M. , Loring S. H. , Regan R.
Published: December 2017

An analog computer to determine dynamic pulmonary compliance (C) and pulmonary resistance (R) on a breath-by-breath basis was tested in guinea pigs and dogs. C was determined by dividing volume by transpulmonary pressure at instants of zero flow. R was determined by the method of electrical subtraction at predetermined flows. In both species the computer outputs and the results of direct analysis were in close agreement. In guinea pigs, the device reliably followed the rapid three- to fourfold changes in C and R resulting from histamine infusion. In unanesthetized dogs, the dispersion and mean values of C and R were similar by the two methods.
Physiological adjustments of young mean to five-hour desert walks
Authors: Dill D. B. , Soholt L. F. , Oddershede I. B.
Published: December 2017

Seven young men undertook a desert walk of 30 km at a rate of 100 m/min. Six finished; the seventh stopped after 24 km. Each satisfied his thirst with cool tap water each hour. Periodic observations included metabolic rate, blood pressure, heart rate, rectal and skin temperature, body weight, and volume of water drunk. Hand sweat was collected each hour and body sweat residues on the skin were collected at the end of the walk. Subjective reports revealed portents of breakdown: aching muscles, painful joints, hot or blistered feet, hunger, and boredom. Cardiovascular adjustment and temperature regulation maintained tolerable conditions. The volumes of water evaporated by the 5-h walkers were about the same. Wet bulb temperatures were below 25 degrees C; all sweat evaporated and was available for temperature regulation. The volume of water drawn from body reserves was closely correlated with concentration of chloride in body sweat; the volume of water that satisfied thirst maintained osmotic pressure.
Energy cost of speec skating and efficiency of work against air resistance
Authors: Di Prampero P. E. , Cortili G. , Mognoni P. , Saibene F.
Published: December 2017

The energy expenditure during speed ice skating (PB=650 mmHg; T=-5 degrees C) was measured on 13 athletes (speed range: 4–12 m/s) from VO2 and (for speeds greater than 10 m/s) from blood lactic acid concentration. The energy spent (O2 equivalents) per unit body wt and unit distance (Etot/V, ml/kg-min) increases with the speed (v, m/s): Etot/v=0.049 + 0.44 X 10(-3) V2. At 10 m/s, Vtot/v amounts then to 0.093 ml/kg-m: about half the value of running. The constant 0.049 ml/kg-m is interpreted as the energy spent against gravitational and inertial forces. The term 0.44 X 10(-3) v2 indicates the energy spent against the wind, the constant 0.44 X 10(-3) ml-s2-kg-1-m-3 being a measure of k/e, where k is the coefficient relating drag to v2, and e the efficiency of work against the wind. From a direct estimate of k in a wind tunnel, e was calculated as 0.11. In running, skating, and cycling k/e is similar (approximately 0.020 ml-s2-m-3 per m2 body area), hence at a given speed the energy spent against the wind is equal. On the contrary, the energy spent against other forces decreases in the above order: 0.19, 0.05, 0.018 ml-m-1 per kg body wt. This explains the different speeds attained in these exercises with the same power output.
Glucagon and plasma catecholamines during beta-receptor blockade in exercising man
Authors: Galbo H. , Holst J. J. , Christensen N. J. , Hilsted J.
Published: December 2017

Seven men ran at 60% of individual maximal oxygen uptake to exhaustion during beta-adrenergic blockade with propranolol (P), during lipolytic blockade with nicotinic acid (N), or without drugs (C). The total work times (83 +/- 9 (P), 122 +/- 8 (N), 166 +/- 10 (C) min, mean and SE) differed significantly. Epinephrine rose progressively above preexercise levels (0.06 +/- 0.01 ng/ml); at exhaustion concentrations in P experiments (2.15 +/- 0.41) were larger than in N (1.08 +/- 0.31) and C (0.72 +/- 0.28) experiments. Norepinephrine increased consistently while insulin decreased. After an initial decrease glucagon concentrations increased progressively in parallel with declining plasma glucose and were at exhaustion always three times preexercise values. Thus beta-adrenergic blockade did not diminish the glucagon response. Nor was this response increased when alpha-receptor stimulation in P experiments was intensified. Carbohydrate combustion was smaller and NEFA and glycerol concentrations in serum larger during C experiments. Alanine concentrations were never raised at exhaustion. Accordingly, neither stimulation of adrenergic receptors nor NEFA and alanine concentrations are major determinants for the exercise-induced glucagon secretion in man. It is suggested that decreased glucose availability enhances the secretion of glucagon and epinephrine during prolonged exercise.
Xenon and nitrogen single-breath washout curves in patients with airway obstruction
Authors: Demedts M. , de Roo M. , Cosemans J. , Billiet L. , van de Woestijne K. P.
Published: December 2017

In patients with chronic obstructive lung disease, we determined single-breath N2 and 133 Xe washout curves, and regional distributions of volumes (Vr) and of 133Xe boluses inhaled at residual volume (VIRV). Patients suffering from emphysema with minimal airway obstruction demonstrated large closing volumes and apicobasal distribution gradients, apparently because of a steep pulmonary recoil pressure-volume curve. In one subject with basal small airway disease there was no vertical gradient in regional residual volume; closing volume was increased with the 133Xe technique but almost absent with the N2 technique. Patients with moderate-to-severe airway obstruction had upward-sloping alveolar plateaus without distinct phase IV, and small apicobasal differences in Vr and VIRV. The latter resulted probably from increased regional differences in time constants counteracting the influence of gravity. Finally, patients with severe airway obstruction and basal emphysema demonstrated a rising N2 but a descending 133Xe plateau; the gradient for VIRV was normal, and reversed for Vr. This pattern was attributed to nongravitational differences in time constants causing a first in-first out distribution.
Novel telemetric system for extraluminal measurement of gastrointestinal motility
Authors: Shearin N. L. , Pfeiffer C. J. , Kilam S.
Published: December 2017

A frequency-modulated, telemetric system with a transducer sensitive to variation in distance between two points was developed and used to measure in vivo small intestinal motor function in unanesthetized dogs. The construction of the system and one application of it to the study of gastrointestinal motility is described. Data were recorded after fasting, 1 h after feeding a standardized meat meal, and after intravenous injections of pentagastrin. A significant increase in motility was seen after pentagastrin injections and feeding as compared to the motility pattern seen in a fasting animal, and the telemetric system was proven adequate for in vivo measurement of motility of the gastrointestinal tract.
Effects of respiratory equipment on endurance in hard work
Authors: Stemler F. W. , Craig F. N.
Published: December 2017

Men ran to a voluntary end point under the following conditions listed in increasing order to resistance, expressed as inspiratory/expiratory in mmH2O at a flow of 4 l-s-1: 1) bare-headed 0/0; 2) face mask 0/0; 3) face mask -6/14; 4) mouthpiece and valves -25/29; 5) face mask -96/62; and 6) face mask -148/60. Average endurance was 545, 490, 434, 392, 343, and 338 s, respectively. Despite the diverse features of the equipment in conditions 2–6, there seemed to be a rather smooth relation between resistance and endurance. There was no indication of a threshold below which endurance would be indifferent to resistance. The duration of the phases of the respiratory cycle was measured by means of a fine thermocouple in the airway. The variability in the duration of the expiratory phase at the end of the run seemed to weaken the concept that the attainment of a critically short expiratory time might be related to the subject's decision to halt running.
pH effects on lactate and excess lactate in relation to O2 deficit in hypoxic dogs
Authors: Cain S. M.
Published: December 2017

Both hypoxemia and alkalemia increase arterial lactate levels, but excess lactate (XL) may be better related to the true O2 deficit and less subject to the pH effect upon glycolysis. To test this idea, 50 anesthetized (30 ml/kg pentobarbital sodium) and paralyzed dogs in five groups were ventilated with low O2 mixtures. Arterial pH was altered by CO2, hyperventilation, and HCO3- so that the average pH of the five groups were 6.99, 7.21, 7.34, 7.53, and 7.54 (+ propranolol). Pyruvate and lactate levels rose at rates roughly corresponding to pH. In all animals, rise of lactate (deltaL), XL and net O2 deficit were linear with time and the slope accurately described the rate of rise. When the ratio of XL rate deltaL rate was plotted against pH, it increased toward unity as pH decreased to 6.9. The ratio of deltaL rate to true O2 deficit rate also showed a significant pH effect by increasing with pH. Ratio of XL rate to true O2 deficit rate, on the other hand, was independent of pH. XL may correct for red cell lactate production which is not affected by O2 supply but is influenced by pH.
Influence of insulin on amino acid uptake by lung slices
Authors: Gregorio C. A. , Massaro D.
Published: December 2017

We examined the transport of amino acids by rat lung slices using mainly 14C-labeled alpha-aminoisobutyric acid ([14C]AIB) as a nonmetabolized amino acid. We found that [14C]AIB is accumulated by the lung in an energy-dependent fashion against a concentration gradient. The uptake is saturable, stereospecific, and follows Michaelis-Menten kinetics suggesting enzyme or carrier mediation across the plasma membrane. Insulin increases the uptake of [14C]AIB and insulin plus glucose increases its uptake even more. The diffusion constant (KD) in the presence of glucose, insulin, or glucose plus insulin is the same, 0.29 h-1; the Vmax is also the same, 83.0 mmol-1–1-h-1, under these three conditions. The apparent Km is 14.0 mM with glucose, 9.0 mM with insulin, and 4.0 mM in the presence of glucose and insulin. We conclude that the uptake of [14C]AIB is increased by insulin, and insulin plus glucose, and, based on this kinetic analysis, this is due to an increased affinity of the transport sites for AIB (decreased Km, unchanged Vmax, and KD).
Can alveolar pCO2 exceed pulmonary end-capillary CO2? Yes
Authors: Gurtner G. H.
Published: December 2017

In 1891 Christian Bohr observed that alveolar PCO2 could exceed arterial PCO2 when high levels of CO2 were present in the inspired air. He proposed that CO2 could be secreted by the lung. His hypothesis was dismissed as being due to experimental error; however, recently the same phenomenon was rediscovered using modern techniques. A possible explanation for the phenomenon may involve coupling between diffusion and chemical reaction of H+, HCO3-, and CO2 in the vicinity of a negatively charged capillary wall, causing the PCO2 to be higher near the wall that in the bulk phase of capillary blood. Alveolar PCO2 is related to the PCO2 near the wall rather than the bulk phase PCO2. The Charged Membrane Hypotheses can explain the phenomenon of CO2 secretion not by a cellular mechanism, but a physical chemical disequilibrium within the capillary which is maintained by blood flow through the capillary.