bluuebunny/crossref_metadata_2025 huggingface dataset:
Maze acquisition and retention in hypothermic mice
Authors: Sudak Frederick N. , Essman Walter B.
Published: December 2017

Three experiments were carried out to demonstrate the relation between learning and retention as affected by a reduction of colonic temperature in mice. Animals rendered hypothermic (T Ε = 3.3 C, 3.4 C) by treatment with 2,4-dichlorophenoxyacetic acid and exposure to cold air (2.0±0.5 C) did not acquire a simple escape response from a water maze within ten training trials. Saline-treated control animals demonstrated acquisition within four trials under similar conditions. Retention of the maze habit was a function of acquisition during training. Retention scores, as well as performance measures, were not affected by a comparable reduction in colonic temperature.

Note:

(With the Technical Assistance of J. R. Blumstein and D. Pennec)

Submitted on January 22, 1962
Right-to-left shunt in normal man determined by the use of tritium and krypton 85
Authors: Mellemgaard K. , Lassen N. A. , Georg J.
Published: December 2017

An aqueous solution of tritium and krypton 85 together with Evans blue dye was injected intravenously in twelve normal subjects during quiet breathing, during apnea, and during voluntary hyperventilation. Arterial blood was sampled within the first 30 sec after the injection to measure the recovery of the two gases. Blood-gas partition coefficients of the two gases at 37 C were determined experimentally and the ratio between them was found to be 3.8 in normal blood. Knowing this ratio it is possible to calculate the fraction of the arterial recovery due to a right-to-left shunt, and that due to alveolar back pressure. The shunt calculated from findings during quiet breathing is 0.26% of the cardiac output. Recoveries during apnea lead to a calculated shunt of identical size, whereas the shunt calculated from the experiments during hyperventilation amounts to only 0.11% of the cardiac output.

Submitted on March 8, 1962
Response of lung volumes and ventilation to posture change and upright exercise
Authors: Hanson John S. , Tabakin Burton S. , Caldwell Edgar J.
Published: December 2017

Variations in size of the various lung volumes due to changes in body position and as a consequence of treadmill exercise were studied in five normal males. Assumption of the upright posture was associated with highly significant increases in total lung capacity, vital capacity, expiratory reserve volume, and residual volume as compared to resting supine values. Level walking was associated with a decrease of expiratory reserve volume, but a further expansion of residual volume. Vital capacity decreased slightly, but total lung capacity increased by virtue of the proportionately large residual volume increases. Elevation of the treadmill to 4° resulted in slight decreases in all lung volumes, total lung capacity evidencing a barely significant decline. Positional changes in ventilation are described, and on the basis of the “lung clearance index” an increased efficiency of ventilation is seen in the upright posture. Factors possibly operative in these alterations are discussed.

Submitted on February 21, 1962
Reflex airway reaction to fluid aspiration
Authors: Colebatch H. J. H. , Halmagyi D. F. J.
Published: December 2017

The mechanism of the lung mechanics changes after fluid aspiration was investigated in sheep, intubated and lightly anesthetized with thiopentone. The increase in venous admixture after intratracheal injection of fluid while breathing 100% oxygen indicated airway closure as the explanation for the associated gross fall in lung compliance (Cl). Atropine sulfate reduced the Cl fall produced by 1 ml/kg body wt. of fluid to a significantly greater extent than prior vagotomy. In vagotomized animals the reaction to fresh water was potententiated by prostigmine. A nonfoaming fluid with a surface tension of 27 dynes/cm had the same effect as fresh water. The reaction to water was not affected by lysergic acid butanolamide or aerosol tetracaine. Intravenous or aerosol isoproterenol reduced the Cl fall after water. These findings show that fluid aspiration invokes a reflex response of the parasympathetic nervous system, with both central and peripheral components producing closure of lung units. The relation of this reflex to other respiratory reflexes is discussed. When inflation alone was ineffective or lead to deterioration, both atropine and isoproterenol helped to reverse the effects of sea and fresh water.

Submitted on March 8, 1962
CO2 and acid-base transients after hyperventilation
Authors: Lipsky Joseph A. , Tomashefski Joseph F. , Carter Earl T.
Published: December 2017

Fourteen male subjects were mechanically hyperventilated by intermittent positive pressure breathing. Tidal volume and respiratory frequency were increased approximately three times and one and one-half times control, respectively. Breath-by-breath analyses of CO2 output indicate a loss of approximately 2.5 liters of CO2 from the body stores in 12 min. Only one-third of that volume was restored during the ensuing 12-min recovery period, mostly as a result of hypoventilation rather than apnea. Over the entire recovery period, the volume of CO2 regained by the blood store approximated 75% of the CO2 content lost during hyperventilation. Under the conditions of these experiments, tissues regained less than 20% of the depleted CO2 store. CO2 retention patterns may be more effective than arterial blood or alveolar air analyses in determining a return to a steady state when tissue stores have been considerably reduced.

Submitted on August 24, 1961
Somatic afferent activity in reflex regulation of diaphragmatic function in the cat
Authors: Sant'Ambrogio Giuseppe , Wilson Michael F. , Frazier Donald T.
Published: December 2017

Experiments were performed to disclose the functional role of afferent activity from the diaphragm, previously described as proprioceptive. Electromyographs were recorded by leads placed in the diaphragm of anesthetized and decerebrate cats. The experiments indicate that in basal conditions interruption of the afferent connections from the diaphragm (i.e., section of the appropriate dorsal roots) did not change the electromyographic activity of the diaphragm. Even during maneuvers known to increase the afferent discharges from the diaphragm, such as negative pressure breathing and abdominal compression, division of the afferent inflow failed to cause a consistent change in the electromyographic patterns of the diaphragm activity. The vagal reflexes from the lungs (Hering-Breuer) remained the same with and without somatic deafferentation. Electrical stimulation of the cervical roots constantly evoked a polysynaptic response recorded either from the diaphragm or the phrenic nerves. This reflex response, without a monosynaptic component, cannot represent a potential myotatic reflex mechanism. The results of these experiments indicate an absence of proprioceptive drive in the reflex regulation of diaphragmatic function.

Submitted on December 7, 1961
Influence of vagal blockade on respiratory and circulatory functions in hypothermic dogs
Authors: Salzano John , Hall F. G.
Published: December 2017

Anatomical and physiological dead spaces were enlarged as a result of reduction in body temperature to 28 C in spontaneously respiring anesthetized dogs. Respiratory dead space at 32 C was not significantly different from that at normal body temperature. Vagal blockade resulted in an increase in tidal volume and decrease in respiratory frequency and increased anatomic and physiologic dead space at normal and reduced temperatures. Alveolar ventilation and cardiac output declined equally (percentagewise) with reduction in body temperature to 32 C; at 28 C alveolar ventilation fell more precipitously so that alveolar ventilation-cardiac output ratio (ventilation-perfusion) at 28 C was approximately one-half that at 37 and 32 C. Arterial-alveolar carbon dioxide pressure differences were independent of temperature and vagal blockade. The results indicate no impairment of gas transport or gas exchange at 32 or 28 C in spontaneously respiring anesthetized dogs.

Submitted on January 11, 1962
Measurement errors in estimating aortic blood velocity by pressure gradient
Authors: Greenfield Joseph C. , Fry Donald L.
Published: December 2017

The computed pressure-gradient technique is important in measuring instantaneous blood flow and velocity in man. Estimation of the instantaneous pressure gradient for this purpose presents many special problems. This study was designed to explore these special measurement problems and to establish certain minimum pressure-recording standards for application of the computed pressure-gradient technique to man. The nature of the functions to be measured was first explored by determining average values and harmonic content of typical pressure, flow, and pressure-gradient curves. In contrast to pressure and flow curves, the harmonic content of pressure-gradient curves was found to exceed the recording capabilities of currently available systems for measuring differential pressure. However, when velocity was computed from pressure gradient, the importance of errors related to higher frequencies is greatly diminished. To meet minimum requirements differential-pressure catheter-manometer systems should have a dynamic imbalance of less than 5% through frequencies of 15 cycles/sec, a single-ended dynamic response uniform (±5%) through 15 cycles/sec, and a static imbalance not greater than ±0.1% over the range 0–300 cm H2O. Although an optimum pressure tap separation could not be precisely defined, visual examination suggested that a tap separation of 8 cm should not be exceeded.

Submitted on April 30, 1962
Alveolar CO2 during breath holding and exercise
Authors: Craig Albert B. , Babcock Stuart A.
Published: December 2017

When 12 healthy adult male subjects held their breath after breathing 100% O2, the PaCOCO2, at the breaking point was higher when they exercised than when they were at rest. Attention was not a factor, and passive exercise did not produce a result different from rest. By repeated breath-holding experiments at different work loads it was possible to demonstrate a systematic error due to the sampling site, the alveolar air. When this error was examined quantitatively, it was found that there is probably no difference in the Pco2 at some critical sensing site at the breaking point under the different conditions of voluntary apnea. Our results imply that exercise may not change the sensitivity to CO2, or at least the sensitivity is not decreased.

Submitted on March 16, 1962
Regional differences in gas exchange in the lung of erect man
Authors: West J. B.
Published: December 2017

Measurements of regional ventilation and blood flow using radioactive CO2 show that both increase from apex to base of the lung; the results are used to build an integrated picture of gas exchange. Ventilation-perfusion ratios at nine levels of the lung have been calculated and differences in local gas exchange deduced. In the resulting model, alveolar O2 tension changes by more than 40 mm Hg from apex to base while CO2 and N2 tensions change by about 14 and 29 mm Hg, respectively. Maximal differences in O2 saturation of end-capillary blood are 4% but differences in CO2 contents of 7 vol % and pH variations of 0.12 units occur. The O2 uptake per unit lung volume increases eightfold down the lung while corresponding variations in CO2 output are less than threefold. N2 passes out of the blood in upper parts of the lung but into the blood in basal regions (net exchange is zero). Over-all O2 uptake and CO2 outputs are reduced by only 2–3% by the ventilation-perfusion ratio inequality, causing alveolar-arterial differences of 4, 1, and 3 mm Hg for O2, CO2, and N2, respectively.

Submitted on April 6, 1962
Changes in serum enzyme levels after exercise in trained and untrained subjects
Authors: Fowler William M. , Chowdhury Sudhir R. , Pearson Carl M. , Gardner Gerald , Bratton Robert
Published: December 2017

Twenty-eight healthy trained and untrained men and eleven untrained women were exercised at several grades on a treadmill or in various athletic events. The serum levels of five enzymes (two transaminases, aldolase, and two dehydrogenases) were compared prior to and at intervals after work. Generally there was a rise after exercise which reached its peak 5 min after completion of the work. The greatest increment of enzyme increase was observed in the untrained subjects and the least in the trained athletes. As the total amount of work output increased the mean serum enzyme levels were correspondingly raised. Aldolase and lactic dehydrogenase showed the least change, malic dehydrogenase increased moderately, while the two transaminases manifested very significant rises after all forms of exercise.

Submitted on September 5, 1961
Heat exchanges of men during caloric restriction in the cold
Authors: Iampietro P. F. , Bass David E.
Published: December 2017

The ability of men to maintain thermal balance during continuous cold exposure (14 days at 15.6 C, sedentary while nude) was assessed under four regimens of caloric intake: a) adequate, 2,800 kcal/day; b) moderate restriction, i.e., sufficient to maintain weight in a warm environment but without the added calories to support shivering, 2,600 kcal/day; c) marked restriction, 600 kcal/day; and d) complete starvation, 0 kcal/day. Respective weight losses for b, c, and d were 1.8, 8.2, and 12.2% body wt. With 600 and 0 kcal/day there was an impaired ability to maintain rectal temperature; under these conditions the men exhibited rectal temperatures 0.7 C lower than when they were on adequate or nearly adequate caloric intake. The men on complete starvation had the lowest heat production of all groups during later days in the cold; however, the data were too variable to demonstrate a close relationship between depressed core temperature and decreased heat production. It is concluded that marked restriction of calories is associated with depressed core temperatures during prolonged cold exposure, due in part to absence of specific dynamic action.

Note:

(With the Technical Assistance of Edward B. Green and John A. Vaughan)

Submitted on April 30, 1962
Local adaptation to cold of Gaspé fishermen
Authors: LeBlanc Jacques
Published: December 2017

This study indicates that Gaspé fishermen have a general peripheral adaptation to cold, since immersion of the hands and feet into ice water gave lower pressor responses than those observed in a control group. This local adaptation is maintained throughout the year. Immersion of the hands in hot water (47 C) reveals no significant differences between the fishermen and control subjects. The thermoreceptors, hypothalamus, cortex, and effector organs are suggested as sites of adaptation in this study.

Submitted on May 3, 1962
Estimation of body fat in young women
Authors: Sloan A. W. , Burt J. J. , Blyth C. S.
Published: December 2017

The body density of 50 healthy young women was determined by underwater weighing, and five skin-fold thicknesses and five girths were measured on each subject. The mean body density was 1.0467 g/ml (sd ± 0.0122), corresponding to 20.06 ± 4.63% by weight of fat in the body by the formula of Keys and Brozcaronek or 22.91 ± 5.58% by the formula of Siri. The mean specific gravity at water temperature 37.5 C was 1.0537 (sd ± 0.0122), corresponding to 22.13 ± 7.08% fat by the formula of Rathbun and Pace. The skin-fold measurement that showed the highest correlation with a composite criterion of skin folds was that over the iliac crest (r = +.92). The best prediction of body density was from skin-fold measurements over the iliac crest and back of arm, which gave a multiple correlation of –.74.

Submitted on October 9, 1961
Bronchoconstriction in man following single deep inspirations
Authors: Lloyd Thomas C.
Published: December 2017

Consistent small transient increases in airway resistance were observed to occur following maximal inspirations by a number of normal subjects. The same effect was also seen after merely attempting inspiration against a closed glottis, and both this and the response after deep inhalation were blocked by prior inhalation of a bronchodilator. An active bronchomotor mechanism is postulated for this response.

Submitted on January 24, 1962
Computer analysis of curves from an infrared CO2 analyzer and screen-type airflow meter
Authors: Noe F. E.
Published: December 2017

Curves from an infrared CO2 analyzer and a screen-type airflow meter were analyzed with a digital computer, and new curves were obtained. Practical applications are illustrated for the data and curves from the computer, and the significance of differences is discussed for the curves from normal, emphysematous, and obese subjects. Curves are shown for breaths with added dead space and for breaths after various periods of breath holding. Also included is a schematic diagram for an analogous analogue computer.

Submitted on October 26, 1961
Stopped-flow measurements of CO and O2 uptake by hemoglobin in sheep erythrocytes
Authors: Sirs John A. , Roughton F. J. W.
Published: December 2017

A stopped-flow method is described to measure spectrophotometrically the rates of uptake of CO and O2 by the hemoglobin of intact sheep erythrocytes. A comparison of the results obtained with the constant flow system has led to further refinement of the latter procedure. A linear relation is found between the rate of uptake and the concentration of the dissolved gas, and the initial percentage rate of saturation is independent of the concentration of the erythrocytes.

Submitted on September 21, 1961
Water diuresis after hypnotic suggestion in hydropenic subjects
Authors: Hulet William H. , Shapiro Theodore , Schwarcz Benjamin E. , Smith Homer W.
Published: December 2017

Four hydropenic female subjects who engaged in sham water drinking associated with suggested satiation of thirst during a short period of hypnosis responded by water diuresis of moderate magnitude after the termination of hypnosis. No evidence of water diuresis was observed under similar conditions in four male subjects, a circumstance possibly related to the effects of bladder catheterization. No significant increase in sodium excretion, sodium excretion fraction, or inulin clearance was observed in any instance.

Submitted on April 9, 1962
Estimation of energy expenditure from expired air
Authors: Liddell F. D. K.
Published: December 2017

Short cut methods of estimating energy expenditure from pulmonary ventilation are examined. Although for any one subject carrying out a particular task, the relationship between his energy expenditure and his ventilation is approximately linear, the equation of the regression line differs from task to task and, for any particular task, from subject to subject. Thus, the estimation of energy expenditure, for the generality of subjects and tasks, from pulmonary ventilation alone, by application of a single simple formula, is seen to be unacceptable as the estimates could be subject to serious error. Analysis of expired air cannot, therefore, be dispensed with but the calculations for estimating energy expenditure in terms of ventilation and the analysis of the expired air, already simplified by Weir, are shown to be even further reducible. A nomogram by which they can be carried out with negligible error is presented.

Submitted on March 1, 1962
Vascular responses produced by histamine by ion transfer
Authors: Abramson David I. , Tuck Samuel , Zayas Agenor M. , Donatello Therese M. , Chu Luke S. W. , Mitchell Roscoe E.
Published: December 2017

The vascular effects of histamine by ion transfer were studied in the hand and/or forearm of 25 normal subjects, using the venous occlusion plethysmographic method. Consistently a marked increase in blood flow was elicited in the hand and a lesser, but still considerable, augmentation occurred in the forearm. Histamine by ion transfer to the hand and foot produced significant vasodilatation in an opposite forearm, thus supporting the view that the drug is absorbed into the systemic circulation to affect distant vascular structures. Further evidence for such a belief was the flushing of the face and neck, associated with very little alteration in blood pressure and pulse rate. As a vasodilating agent, histamine by ion transfer was found to compare more than favorably with such agents as Mecholyl by ion transfer, ultrasound, short-wave diathermy, reflex vasodilatation, and wet heat.

Submitted on September 10, 1962
Silver-silver chloride electrode as a nonpolarizable bioelectrode
Authors: Feder Walter
Published: December 2017

A thermal-electrolytic method for the preparation of Ag AgCl electrodes suitable for measurement of bioelectrical changes in the microvolt range is given in detail. A potential of 0.5 mv or less between electrode pairs is easily attained; and such electrodes will accurately measure emf generated by both steady and fluctuating phenomena down to ±5 μv under routine laboratory conditions. Studies in the variations in potential for pairs of electrodes from the time they are introduced into the circuit until they reach a stable state, as well as long-term drift are presented. These data are analyzed in terms of activation, ohmic, and concentration polarization effects.

Submitted on July 19, 1962
Effect of exercise on pulmonary diffusing capacity
Authors: Turino G. M. , Bergofsky E. H. , Goldring R. M. , Fishman A. P.
Published: December 2017

The effect of graded exercise on the pulmonary diffusing capacity for both oxygen and carbon monoxide measured simultaneously was studied in healthy young adults by steady-state methods. Pulmonary diffusing capacity for oxygen increases progressively with increasing severity of exercise; it exceeds the DlCO at high levels of exercise by amounts greater than can be accounted for by the difference in diffusivity of the test gases. Diffusing capacity for carbon monoxide increases less than DlOO2 for comparable grades of exercise but no definite plateau value could be established. The supine or upright body position does not influence the values of either DlOO2 or DlCO during exercise. Diffusing capacity of the lung for oxygen does not limit the maximum levels of exercise which may be achieved by normal man.

Submitted on August 6, 1962
Effect of a systemic A-V fistula and of pulmonary embolization on diffusing capacity
Authors: Williams M. Henry , Sobol Bruce J.
Published: December 2017

Opening an aortic-caval fistula in anesthetized dogs was associated with slight but significant increase of the steady-state diffusing capacity of the lungs. Extensive pulmonary embolization with glass beads resulted in a slight and insignificant fall of the diffusing capacity. Increased pulmonary blood flow and obstruction to pulmonary arterioles do not appear to be associated with marked increase and decrease of the diffusing capacity.

Submitted on October 5, 1962
Effect of hyperthermia on peripheral dark adaptation rates
Authors: Kissen Abbott T.
Published: December 2017

Supersonic or hypersonic aircraft flight can produce hyperthermia in crew members. Dark adaptation is a physiologic response possibily influenced by such stress. Biochemical regeneration rate of rhodopsin might be altered if retinal blood or tissue temperatures are raised by this hyperthermia. Peripheral dark adaptation curves were obtained on five subjects at comfort (21.0 C) and 65.6 C temperatures alternately, using a modified Hecht-Schlaer adaptometer. In 24 heat experiments, subjects were exposed to 65.6 C ambient air temperature for 55 min after which the heat was shut off. Chamber temperature declined but the subjects remained in a relatively constant hyperthermic condition during the subsequent 35-min dark adaptation test. The criterion used here for hyperthermia is the elevation and maintenance of the rectal temperature at least 0.56 C above corresponding control temperature. Curves obtained under hyperthermic conditions (with the exception of the initial and terminal values) differ, with statistical significance, from controls, indicating a facilitation of dark adaptation under the imposed thermal stress conditions.

Submitted on July 9, 1962
Contralateral effects of thermal stimuli on manual performance capability
Authors: Clark R. Ernest , Flaherty Charles F.
Published: December 2017

The performance capability of one hand was studied as a function of its surface temperature and that of the contralateral hand. Three findings were determined to be statistically reliable for the subject sample tested: a) when the performing hand itself was cooled to a surface temperature of 40 F, performance decrements appeared which were independent of the temperature of the contralateral hand; b) when the performing hand was kept warm, cooling of the nonperforming hand resulted in an average reduction of 33% in the time typically needed for the completion of the manual task; and c) the surface temperature of a hand not exposed to the cold was found to fall an average of 2 F below its normal level when the contralateral hand was cooled to surface temperatures of 55 F or lower.

Submitted on August 20, 1962
Body-temperature regulation in the normal and cold-acclimatized cat
Authors: Adams Thomas
Published: December 2017

The role of the anterior hypothalamus as a temperature-sensible area serving a thermal regulatory input function for body-temperature control in cats living at 25 C (noncold acclimatized) or 5 C (cold acclimatized) was tested by selectively changing diencephalic temperatures in the unanesthetized animal resting at 23 C ambient temperature. Extremity and internal body-temperature and metabolic-rate responses were monitored during the induced thermal shifts. Both groups of animals showed greater peripheral vasomotor and internal body-temperature changes consequent to hypothalamic heating than cooling; no modification of these test patterns was noted as a function of whole-body cold acclimatization. The temperature-sensible anterior hypothalamic areas appear to be more influential in protecting against hyperthermia than hypothermia and their function in biothermal control does not appear to be altered by whole-body cold acclimatization.

Submitted on November 1, 1962
Combined effect of cold and alcohol on heat balance in man
Authors: Andersen K. Lange , Hellstr⊘m B. , Lorentzen F. Vogt
Published: December 2017

The combined effect of alcohol and cold on the heat balance of human subjects was studied by measuring heat production, deep body temperature, and skin surface temperature during an 8-hr night. Moderate doses of alcohol had no deteriorative effect on heat balance during prolonged mild cold exposure. The only noticeable effect of alcohol under these conditions is a hypnotic effect giving the subjects more comfort and sleep. If the cold stress becomes severe, some risk is involved by consuming alcohol, as an insufficient metabolic compensation was observed in one subject resulting in a greater drop of the rectal temperature than when the same subject rested nonintoxicated under the same environmental conditions.

cold and alcohol

Submitted on January 14, 1963
Cardiovascular responses to head-stand posture
Authors: Rao Shanker
Published: December 2017

Reports of cardiovascular responses to head-stand posture are lacking in literature. The results of the various responses, respectively, to the supine, erect, and head-stand posture, are as follows: heart rate/min 67, 84, and 69; brachial arterial pressure mm Hg 92, 90, and 108; posterior tibial arterial pressure mm Hg 98, 196, and 10; finger blood flow ml/100 ml min 4.5, 4.4, and 5.2; toe blood flow ml/100 ml min 7.1, 8.1, and 3.4; forehead skin temperature C 34.4, 34.0 and 34.3; dorsum foot skin temperature C 28.6, 28.2, and 28.2. It is inferred that the high-pressure-capacity vessels between the heart level and posterior tibial artery have little nervous control. The high-pressure baroreceptors take active part in postural adjustments of circulation. The blood pressure equating mechanism is not as efficient when vital tissues are pooled with blood as when blood supply to them is reduced.

man; heart rate; blood flow; skin temperature

Submitted on January 3, 1963
Validity of heart rate as an indicator of cardiac strain
Authors: Maxfield Mary E. , Brouha Lucien
Published: December 2017

Total cardiac cost is a measurement of the area under the curve obtained by plotting the heart rate for each minute during work and recovery. In a constant environment it varies with the work accomplished in a given time and, for a constant work performance, it varies with the severity of the conditions. The work accomplished per beat has a reciprocal relation to total cardiac cost when work and recovery times are constant. Recovery cost and the average of three early recovery heart rates, P1, P2, and P3, vary linearly with total cardiac cost when work or environmental stress increases. In these experiments P1, P2, and P3 are the heart rates per minute recorded during the last 30 sec of the 1st, 2nd, and 3rd min, respectively, of the recovery period. These recovery pulse rates provide a simple measurement of the degree of cardiac strain induced by work in any environment.

cardiac cost; recovery pulse rates; work rate; warm environment; human male; human female

Submitted on July 13, 1961
Square-wave electromagnetic flowmeter employing commercially available recorder
Authors: Scher Allen M. , Zepeda Julian , Brown Otis F.
Published: December 2017

The availability of a stable, highly sensitive commercial recorder led us to construct a simple delay unit and square-wave driver for the purpose of measuring blood flow electromagnetically. The construction of the flowmeter heads is described briefly, and some analysis is made of possible deficiencies in flowmeter heads employing iron cores. The flow-measuring system is sensitive and linear and, when the magnet drive is turned off, the base line is within a few microvolts of true zero flow.

blood flow in intact animals; epoxyresin embedding implantation

Submitted on March 4, 1963
Indocyanine green densitometry in flowing blood compensated for background dye
Authors: Edwards Anthony W. T. , Isaacson James , Sutterer William F. , Bassingthwaighte James B. , Wood Earl H.
Published: December 2017

Blood is nonhomogeneous; hence, the relationship between light transmission and increasing concentration of dye in whole blood is never the perfect exponential curve predicted by Beer's law. Instead, as the concentration of indocyanine green is increased to high levels (40 mg/liter) the light transmission decreases exponentially toward an asymptote at 6–8% transmission for nearly monochromatic densitometers (half-band width: 13–20 mμ), but at 30–40% for densitometers using light of wide-band width. Consequently, following recording of a dilution curve, circulating background dye reduces the change in transmission per unit increase in dye concentration in subsequent curves. This decrease in sensitivity cannot be compensated for by a simple increase in the sensitivity of the densitometer or in the intensity of its light source. Compensation can be attained, however, if increasing densitometer sensitivity is associated with the automatic scale expansion provided when a suppressed zero point is used. At correct zero suppression, the deflection for zero output of the densitometer coincides with the asymptotic transmission value mentioned above.

indicator-dilution in circulation; blood flow measurement; blood optical density; dye dilution technic; cardiac output measurement

Submitted on April 15, 1963
Effects of carbon dioxide inhalation on sweating
Authors: Bullard Robert W.
Published: December 2017

Inhalation of 6% carbon dioxide by male subjects exposed to three different ambient temperatures resulted in increased sweating as measured by resistance hygrometry. The increase, which occurred in all body areas studied, reached approximately 100% over the control levels. All measured body temperatures decreased during or immediately following the carbon dioxide period. In the recovery period a marked depression of sweating occurred which ended as skin temperatures increased.

body temperature; thermal effector activity (cyclic sweat gland activity); skin temperature; tympanic membrane and hypothalamus temperatures; resistance hygrometry responses to heat

Submitted on April 24, 1963
Prolonged exposure of young rats to an oxygen atmosphere at reduced pressure
Authors: Dines John H. , Hiatt Edwin P.
Published: December 2017

The effect was studied of exposing 12 young male white rats to an atmosphere almost free of nitrogen but with an alveolar Po2 the same as that of the 12 control animals breathing ambient air. This was achieved by keeping the experimental animals in almost pure oxygen at a reduced pressure. Experimental and control animals were in closed chambers with oxygen being supplied from a spirometer while Co2 was absorbed. Humidity and temperature were closely regulated. Provision was made for handling the animals and supplying them with food and water without changing the chamber environment. A successful experiment lasting 24 days was completed, not including observation periods of 6 days be-before and 8 days after the experiment when both groups were kept in air. No consistent difference was noted in rate of growth, oxygen consumption, food consumption, water intake, hemoglobin concentration, or behavior of the two groups. A decreased rate of urine production by the rats in the experimental group was attributed to an increased evaporative loss of water in the rarified atmosphere.

nitrogen-free atmosphere; growth rate; O2 consumption; reduced pressure; oxygen low pressure atmosphere

Submitted on March 20, 1963
Aerobic and anaerobic metabolism in exercising dogs
Authors: Cerretelli P. , Piiper J. , Mangili F. , Ricci B.
Published: December 2017

For an analysis of the energy expenditure as related to the work performance in exercising dogs, the O2 consumption and the lactic acid production were determined at rest and during running on a treadmill at varying speeds (from 4 to 16 km/hr) and inclines (from 0 to +20%). The incline being constant, the O2 consumption was found to increase linearly with the speed. Although the maximum O2 intake probably could not be reached, the highest value measured, 100 ml O2/kg min, was about twice the average maximum O2 intake value for untrained men. The lactic acid production became detectable as the metabolic rate reached about 280 cal/kg min and increased at higher metabolic levels. The contribution of the anaerobic metabolism to the increase of the total metabolic rate due to exercise attained about 5% at the highest metabolic rate that could be measured, 580 cal/kg min The energy cost of running per kilogram body weight was found to be the same as in man for running on the level, 1.0 kcal/kg min; it increased more than in man in uphill running. The efficiency of running, as for man, was found to be independent of the speed.

O2 consumption during running; lactic acid production during running; pyruvic acid production during running; energy cost and mechanical efficiency

Submitted on July 15, 1963
An analysis of pressure-volume characteristics of the lungs
Authors: Salazar Eduardo , Knowles John H.
Published: December 2017

By analysis of the retractive forces of the lungs it was found that the pressure-volume characteristics of the lungs may be expressed by an exponential function. The curve described by such expression could be fitted to the experimental data obtained in 20 normal subjects. A half-inflation pressure (h) was defined which makes possible the evaluation of the retractive forces of the lungs by a measurement independent of lung size and accounting for known curvilinearity. H is a useful index of the stiffness of the organ and it is defined as the increase in transpulmonary pressure necessary to inflate the lungs halfway to the maximal pulmonary volume from any resting level. The mean value of h for the group was 7.58 ± 2.53 cm H2O. The half-inflation pressure is independent of the level of measurement within the inspiratory capacity and it does not vary with or depend on the size of the lungs. It may therefore be a more useful expression of the retractive forces of the lungs than compliance.

pulmonary retractive forces; lung stiffness; compliance half-inflation pressure and lung size; VC and half-inflation pressure; FRC and half-inflation pressure; new expression for compliance; pressure-volume curve

Submitted on March 4, 1963
Effects of aspartic acid salts (Mg and K) on physical performance of men
Authors: Consolazio C. Frank , Nelson Richard A. , Matoush Le Roy O. , Isaac Gerhard J.
Published: December 2017

The performance of twelve men was measured during a 9-week study. Six of the men received placebos and six received 2 g of magnesium and potassium salts of aspartic acid (Spartase) daily during 5 weeks of therapy. There was no significant difference in metabolic rate and RQ between the control or aspartate supplemented groups during moderate exercise and the recovery period after moderate exercise. Differences in other factors, such as maximum breathing capacity, vital capacity, breath-holding time, etc., were also nonsignificant. A few significant differences appeared between groups for the neuromuscular excitability values, which because of their erratic pattern probably were due to chance. Under the stresses imposed in this study there seemed to be no convincing evidence of the beneficial effects of aspartate therapy.

exercise; neuromuscular fatigue; metabolic rate, respiratory measurements and physical fitness index under aspartate therapy; ergogenic drugs

Submitted on May 8, 1963
Determinants of duration of left ventricular ejection in normal young men
Authors: Jones William B. , Foster Glenn L.
Published: December 2017

The factors governing the duration of ejection were studied by statistical techniques at rest and during exercise in man. Data consist of 207 points in 20 subjects. Linear stepwise regression analysis results in the following formula for the prediction of the duration of ejection from the heart rate, stroke index, and the aortic diastolic pressure: duration of ejection = .36646 - .00108 (rate) - .00036 (diastolic pressure) + .00076 (stroke index). The correlation coefficient is 0.90 on comparison with the measured duration of ejection. The error of estimate is .0155 sec. The validity of the three variables was confirmed by factor analysis. Heart rate was found to be the major determinant of the duration of ejection. Stroke index and pressure have a relatively minor but statistically significant effect.

ventricular ejection time prediction and calculation; factor analysis of ventricular ejection; cardiac output during exercise; heart rate, stroke index, and ventricular ejection; aortic diastolic pressure and ventricular ejection

Submitted on July 18, 1963
Measurement of total pressure of dissolved gas in mammalian tissue in vivo
Authors: Lategola Michael T.
Published: December 2017

An in vivo method for the quantitative estimation of total gas pressure in mammalian tissue has been established. This method utilizes a rigid-walled capsule specially constructed to be permeable to O2, CO2, and N2, but negligibly permeable to water vapor. The results obtained, after subcutaneous implantation of this capsule, directly demonstrate that the total gas pressure in the adjacent tissue interface is about 40–50 mm Hg less than the concomitant atmospheric pressure. This pressure difference is a result of the metabolic gas exchange of the tissue interface.

tissue metabolism; blood-gas tensions; tissue-blood gas diffusion; gas-bubble physiology; dog tissues total gas pressure

Submitted on July 25, 1963
In situ pressure-radius-length measurements in ascending aorta of anesthetized dogs
Authors: Patel Dali J. , Fry Donald L.
Published: December 2017

Instantaneous pressure-radius-length relationship was studied in the ascending aorta of ten living dogs. Results indicate: 1) longitudinal and circumferential strains in the ascending aorta are large as compared to other segments of the aorta, and 2) it is suggested that the intravascular pressure may not be the only radially distending stress since other forces due to contraction of the heart seem to play a role in this local area.

Note:With the Technical Assistance of Joseph M. Pearce

mechanical properties ascending aorta living dog; stress-strain relation ascending aorta living dog

Submitted on September 27, 1963
Hemodynamic response of normal men to graded treadmill exercise
Authors: Tabakin Burton S. , Hanson John S. , Merriam Thornton W. , Caldwell Edgar J.
Published: December 2017

The physiologic variables defining the circulatory and respiratory state in normal man have been measured in recumbency, standing at rest and during progressively severe grades of exercise approaching near-maximal levels. Indicator-dilution technique was used for determination of cardiac output with simultaneous radio-electrocardiographic recordings of heart rate. Direct intra-arterial pressure measurements were utilized for calculation of peripheral vascular resistance. Minute volume of ventilation, oxygen utilization, and carbon dioxide elimination were obtained from analysis of expired air collected at the time of each cardiac output determination. A peak mean workload of 1,501 kg-m/min was realized during the treadmill exercise. Increases in cardiac output over the range of exercise employed correlated well with indices of workload such as heart rate, oxygen utilization, and minute volume of ventilation. There was no correlation of stroke volume with these indices. It is concluded from examination of individual stroke-volume responses that a progressive increase in stroke volume is not a necessary or constant phenomenon in adapting to increasing workload.

cardiac output in treadmill exercise; dye-dilution cardiac output determinations; arterial pressure during upright exercise; stroke-volume response to graded treadmill exercise; exercise response of cardiac output and stroke volume; peripheral vascular resistance response to position and exercise; treadmill exercise—effects on cardiac output, stroke volume, and oxygen uptake; minute ventilation, cardiac output, and stroke volume during exercise; carbon dioxide elimination during treadmill exercise; heart rate and cardiac output during treadmill exercise; exercise; physiology

Submitted on July 12, 1963
Reliability of estimation of metabolic levels from respiratory frequency
Authors: Ramanathan N. L.
Published: December 2017

The reliability of estimating the physiological energy cost from the respiratory frequency has been tested from 114 exercise experiments on 11 volunteers. A correlation according to E (kcal/min) = -3.06 + 0.198 R (no/min) was obtained between energy consumption and breathing rate. This regression was highly significant (P < 0.01) with a correlation constant of 0.93 and standard error of only 0.46 kcal/min. The convenience of the method in comparison with pulse rate and pulmonary ventilation methods which have similar correlation and accuracy, have been discussed. In states of low energy metabolism and also in the performance of severe muscular tasks, when oxygen debt may occur, the present relation may not strictly apply. Breath amplitude also affects energy levels, but it seems to bear no relation to the effect of respiratory frequency. Techniques for observing respiratory frequencies accurately and for deriving the best estimate of energy cost under field conditions are described. Determinations of energy consumption to the first approximation are readily achieved by this method.

exercise; respiratory rate and energy expenditure in man pulmonary ventilation and respiratory rate; work output measurement

Submitted on May 21, 1963
Calibration of an impedance pneumograph
Authors: Kubicek W. G. , Kinnen E. , Edin A.
Published: December 2017

An experimental calibration of an electrical impedance pneumograph is presented over a range of tidal volumes from 250 to 4,000 ml. Transthoracic impedance measurements were made on four subjects using 1-in. cup electrodes, and at a frequency of 100 kc/sec. A 1-ohm change of impedance magnitude corresponding to an average tidal volume of 830 ml was observed, based on a total of 1,063 measurements. The standard deviation of these data was approximately 50% for low tidal volumes and 30% for the larger tidal volumes. Data from individual subject trials indicated significant variations in the calibration constants and regions of apparent linearity, both between subjects and between trials on each subject. Experimental records of the change in impedance magnitude as a function of inspired air volume during inspiration are included to illustrate typical variations.

plethysmography, impedance; impedance, transthoracic; tidal volume, measurement of; respiration meter

Submitted on July 29, 1963
Base-line effects on response of stroke volume to leg exercise in the supine position
Authors: Frick M. H. , Somer Timo
Published: December 2017

Cardiac output was measured with dye dilution in normal subjects at rest in horizontal position, at rest supine with the legs on the pedals, and during increasing work loads. Experiments were designed to clarify the effect of leg raising on comparisons of stroke volume at various levels of exercise. Leg raising evoked a 19% increase in stroke volume and a decrease in heart rate. Oxygen uptake and A-V O2 difference remained unaltered. In comparing stroke volume at mild exercise with leg-raised resting position, no change occurred contrasting the significant rise when compared with horizontal position. At mild exercise cardiac output response was relatively flat, whereas A-V O2 difference rose sharply. At heavier exercise cardiac output rose more steeply and approximately linear to oxygen consumed. Stroke volumes at these loads were significantly higher than levels in both of the resting positions. Ignorance of the effect of leg raising results in misinterpretation of the stroke volume data at low levels of supine exercise when greatly enhanced tissue extraction of oxygen allows smaller blood flow increments.

base line in exercise; exercise stroke volume; stroke volume, exercise; stroke volume, base line; supine exercise

Submitted on December 13, 1963
Effect of exercise on zonal distribution of pulmonary blood flow
Authors: Read John , Fowler K. T.
Published: December 2017

Redistribution of pulmonary blood flow was studied by means of the cardiogenic oscillations of expired gas tensions in seven normal subjects during exercise in the vertical posture. The results are expressed in terms of Qr, the ratio of blood flow per unit of alveolar volume between upper and lower zones of the lungs, and are compared with the response of the same subjects to alveolar hypoxia. In six subjects, Qr rose on exercise by an amount which varied from subject to subject and from day to day, depending on the resting level of Qr. A further subject usually failed to increase Qr on exercise. Aminophylline reduced resting Qr in some subjects. It is concluded that the response of Qr to exercise depends on the extent to which active pulmonary vasodilatation occurs. Differences in the response of Qr to exercise, hypoxia, and aminophylline are interpreted in terms of differing initial pulmonary vasomotor tone.

gas tension; argon; alveolar volume; alveolar hypoxia

Submitted on August 5, 1963