bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of sleep on hypoxic stimulation of breathing at sea level and altitude
Authors: Reed Donal J. , Kellogg Ralph H.
Published: December 2017

The effect of sleep on the level of hypoxia in four adult male, sea-level residents was studied at sea level, during 23 days at 14,250 ft. and after return to sea level. The subjects, awake and asleep, breathed graded O2-N2 mixtures, each followed by a high O2 gas. Sleep did not significantly affect the hypoxic drive of breathing as evaluated from the steady-state levels of ventilation or from the immediate respiratory depression produced by interrupting hypoxia. At the ambient altitude O2 tension, arterial O2 saturation indicated by ear oximeter fell 4–8% with sleep. This fall in arterial oxygenation is believed to be sufficient to help explain the increased severity of mountain sickness which is commonly associated with sleep at altitude.

Submitted on June 6, 1960
Cutaneous vasomotor nerves to the head and trunk
Authors: Blair D. A. , Glover W. E. , Roddie I. C.
Published: December 2017

Simultaneous measurements of skin temperature of various skin areas of the body were made during indirect cooling and heating of the body. Cooling the body caused a much larger fall in the nose and finger temperature than in mouth temperature, indicating active vasoconstriction in these areas. In the ear, cheek, chest and forehead there was no evidence for vasoconstriction. Evidence of vasodilatation in all the skin areas studied was obtained when the body was indirectly heated. Blocking the vasomotor nerves to the ear resulted in a large increase in skin temperature and, during body heating, the skin temperature of the normal ear did not exceed that of the nerve-blocked ear. It was concluded that the changes in ear blood flow subserving temperature regulation are mainly due to alterations in vasoconstrictor tone. In the chest and cheek, cutaneous nerve block did not alter skin temperature, yet it reduced the rise in skin temperature normally seen during body heating. It was concluded that the vasodilatation normally seen in these areas is not due to release of vasoconstrictor tone, but rather to an active vasodilator mechanism, mediated through fibers running with the cutaneous nerves.

Submitted on May 27, 1960
Effects of somatotropin in rats acutely exposed to adverse environments
Authors: Hale Henry B. , Mefferd Roy B.
Published: December 2017

Metabolic effects of acute (24-hr.) exposure to low barometric pressure (380 mm Hg), heat (35°C), or cold (2°C) were determined in fasting rats which had received subcutaneous injections of somatotropin (0.5 mg/100 gm b.wt.) 24 hours before and immediately before exposure. Comparison was made with rats exposed to the same conditions without pretreatment with somatotropin and with controls held under neutral conditions of temperature and pressure (24°C, 750 mm Hg). Somatotropin modified environmentally induced changes in 24-hour urinary excretion of urea, uric acid and phosphate and the urinary Na/K, Ca/P and uric acid/creatinine ratios. Suggestive evidence was thus obtained to support the hypothesis that somatotropin contributes to homeostasis.

Submitted on October 26, 1959
A unified system for evaluation and selection of heat stress candidates
Authors: Gold Joseph
Published: December 2017

A system for the evaluation and selection of heat stress candidates has been developed that is concerned not only with the extent to which an individual is capable of dissipating heat, but also the price he must pay for so doing. The former is dealt with through the concept of effective body heat storage ( qe); the latter, through a newly developed index of strain ( IG). Effective body heat storage is defined as that amount of storage obtained if a subject were able to go into a heat chamber already fully equilibrated with it and with all heat-dissipating mechanisms fully operating. The index attempts to express a new concept, accumulative circulatory strain, in terms of heart rate alone. The best subjects (usually in the young age groups) show a low ( IG) and low ( IG); the worst (usually in the older age groups) show a high ( qe) and low ( IG). All subjects were maintained at rest during heat exposure.

Submitted on April 8, 1960
Energy metabolism in college girls
Authors: Banerjee Sachchidananda , Barua Anita , Ghosh Arati
Published: December 2017

Energy expenditures during different activities of 24 college girls were determined by measurement of oxygen consumption. The energy cost of various activities expressed as Calories per square meter of body surface per hour was as follows: basal metabolic rate (BMR), 28.75 α 0.47; lying at rest, 30.95 α 0.60; sitting at rest, 36.03 α 0.66; sitting at study, 34.59 α 0.63; sitting at household work, 80.71 α 3.50; standing at laboratory work, 48.71 α 2.70; walking, 110.27 α 2.70; ascending stairs, 137.83 α 4.60; and descending stairs, 90.39 α 3.25. The average total daily energy expenditure of the subjects, determined for a period of 7 days, was 1503 Cal. and the average daily intake was 1507 Cal. Energy expenditure during standardized work on the bicycle ergometer was determined in six college girls by measurement of oxygen consumption. The energy cost of work done equivalent to 150 kpm/min. was found lowest when the work was performed in the basal state, highest 1 hour after a heavy meal, and intermediate 4 hours after the meal. The results indicated that performance of work was more efficient on an empty stomach than when it was full.

Submitted on September 19, 1960
Fluctuation of peripheral blood flow in subjects with circulatory impairment
Authors: Franke Ernst K.
Published: December 2017

Fluctuations of the capillary blood flow in the skin of the hands of cardiac patients were compared with those of normal controls. In normal subjects the peripheral blood flow undergoes spontaneous, rhythmic fluctuations of a period of 30–60 seconds, whose main function is the regulation of the body temperature. These fluctuations were recorded by means of a probe that was sensitive to the effective thermal conductivity of the skin, which is proportional to the blood flow in its capillaries. The essential elements of the probe are two wires (constantan, 0.2 mm) of 1-cm length that are in contact with the skin at a mutual distance of 0.5 cm. One of the wires is heated by alternating current. The temperature difference that therefore develops between these wires is proportional to the thermal conductivity of the skin. It is recorded by means of thermocouples in contact with the wires. It was found that the cardiac patients had, on the average, a substantially lower amplitude of fluctuations than the normal controls. It is assumed that this may be attributed to anatomical changes of the arteriolar walls, which cause increased rigidity.

Submitted on August 10, 1959
Stability of basal metabolic rate on a polar expedition
Authors: Lewis H. E. , Masterton J. P. , Rosenbaum S.
Published: December 2017

The basal metabolism studied in 29 young adults on 349 occasions over 2 years in the Arctic was 37.4 (sd α 3.7) kcal/m-2/hr-1, and well within the normal British standards. The variability showed no relationship to season. On polar expeditions, men's physiologically significant exposure to cold is small because of efficient protection by clothing and shelter. Information is needed about precise differences of microclimate in the polar regions and at home. Field work could more profitably be directed to the cognate problem of costs of various activities in the cold rather than basal metabolic rate.

Submitted on April 25, 1960
Relationship of aortic pressure and diameter in the dog
Authors: Barnett G. O. , Mallos A. J. , Shapiro A.
Published: December 2017

The measurement of the relationship between aortic diameter and aortic pressure is of importance in the general problem of blood flow measurements. This relationship was examined in the upper descending aorta of the anesthetized thoracotomized dog using a specially devised strain-gauge caliper and a catheter-manometer pressure recording system. It was found that the slope of the graph of mean diameter vs. mean pressure (“mean extensibility index”) was linear between mean pressures of 60–140 mm Hg, and was only slightly affected by intravenous norepinephrine. The ratio of the change in diameter to the change in pressure for a single pulse (“dynamic extensibility index”) was not significantly different from the mean extensibility index below mean pressures of about 130 mm Hg. The dynamic extensibility index was moderately decreased by norepinephrine.

Note:

(With the Technical Assistance of Walter Gray)

Submitted on August 8, 1960
Pulmonary gas transport as influenced by a hypergravitational environment
Authors: Steiner Sheldon H. , Mueller Gustave C. E. , Cherniack Neil S.
Published: December 2017

Inertial effects on pulmonary gas exchange were measured during forward acceleration at 6 and 8 g. During the 3-min-acceleration plateau, O2 uptake decreased a mean of 16 ml/min at 6 g and 71 ml/min at 8 g. CO2 excretion increased 62 ml/min at 6 g and only 30 ml/min at 8 g. The respiratory exchange ratio increased from 0.83 to 1.17 at 6 g and 1.24 at 8 g. There was a marked increase in the minute volume of ventilation. During the recovery periods, an additional 470 ml O2 was consumed; 360 ml CO2 was excreted above control values for 6 g; 650 ml O 2 was consumed; and 580 ml CO 2 was excreted for 8 g. The increased metabolic work at the g levels studied was small, representing approximately 150 ml/min O 2. The respiratory exchange ratio was well above 1.00, and a large O 2 debt accumulated. Exercise at 8 g resulted in a marked increase in O 2 uptake, which eliminated the possibility that the observed effects were caused by impaired alveolar ventilation or diffusing capacity. Cardiac output has been reported essentially unchanged or slightly increased during forward acceleration and, therefore, the response cannot be explained by a decrease in pulmonary blood flow. The evidence suggests that the diminution in O 2 exchange and impairment in CO 2 excretion represents a combination of alteration in the pulmonary ventilation to blood flow ratios and peripheral arterial shunting.

Note:(With the Technical Assistance of Justin L. Taylor)

Submitted on February 8, 1961
Left ventricular heat production measured by coronary flow and temperature gradient
Authors: Neill William A. , Levine Herbert J. , Wagman Richard J. , Messer Joseph V. , Krasnow Norman , Gorlin Richard
Published: December 2017

The study of energetics of the left ventricular myocardium, normally based on its oxygen consumption and mechanical work performance, can be extended by determining its heat production as well. By considering all forms of energy input and output of the left ventricle, calculations were made of left ventricular net heat production under a variety of hemodynamic conditions. One of the mechanisms for removal of the heat produced is provided by the coronary blood, which is warmed in transit through the myocardium. Direct measurements of the rate of heat removal by the coronary circulation were made from coronary flow rate and veno-arterial temperature gradient. The fraction of left ventricular net heat production which is removed by the coronary perfusion is proportional to coronary flow rate. The fraction at a given flow rate is sufficiently reproducible to permit estimation of total heat produced from the portion measured in the coronary circulation. Certain of the theoretical applications of heat data may require more accuracy than appears feasible by this method. Which of the applications discussed will prove practical remains to be determined.

Submitted on February 13, 1961
Effect of hypothermia on responses to imposed trachea obstruction
Authors: Hall F. G. , Salzano John
Published: December 2017

Respiratory and circulatory responses to three levels of imposed tracheal obstruction were measured in normothermic dogs; the same measurements were repeated after the blood temperature of the animals had been reduced to 28 C by immersion in ice water. Respiratory rate increased, tidal volume decreased, and arterial oxygen saturation progressively declined as a result of tracheal impedance at 37 C. The induction of the hypothermic condition caused a fall in respiratory rate, an increase in tidal volume, and no change in arterial oxygen saturation in response to the same obstruction to air flow. Cardiac output and systemic pressure increased as the magnitude of obstruction was increased in the normothermic animals but were not altered by the same degree of obstruction in the hypothermic animals. The differences in responses observed at the two temperatures studied seem to be related to the degree to which hypoxia develops in the normothermic animals as a result of tracheal air flow impedance.

Submitted on May 16, 1961
Pulmonary arterial shunting in man during forward acceleration
Authors: Steiner Sheldon H. , Mueller Gustave C. E.
Published: December 2017

The arterial blood gases were determined during forward acceleration 90∘ to the acceleration vector at 6 g and 8 g breathing room air and at 8 g breathing 100% oxygen. Arterial saturation fell to 84% at 6 gand 75% at 8 g. Prebreathing O2 for 15 min prior to acceleration with continued inhalation during the acceleration plateau only partially corrected the undersaturation to 86% at 8 g. Recovery was not complete in 3 min unless O g therapy was used. Whole blood carbon dioxide content was depressed at 6 g and 8 g on room air, but this was corrected by O g inhalation. However, during the recovery period while breathing oxygen the carbon dioxide content was depressed. pH was reduced and pCO g elevated slightly during each acceleration period. Since cardiac output and alveolar ventilation have been reported to be essentially unaltered during forward acceleration at these magnitudes, the observed effects must represent substantial alterations in the individual ventilation to blood flow ratios throughout the lung, with approximately 50% of the cardiac output shunted through totally nonventilated areas at 8 g. There also must be some inadequately perfused or nonperfused peripheral areas, as evidenced by the fall in CO g content and pH and the accumulation of a substantial O g debt previously reported during acceleration.

Note:

With the Technical Assistance of Alice M. Caton and Justin L. Taylor, Jr.

Submitted on June 12, 1961
Anthropometric fractionation of body weight
Authors: Behnke Albert R.
Published: December 2017

Body weight ( W) may be predicted with an accuracy of ±2% from the sum ( CCCC) of 11 anthropometric circumferences and stature ( h). Additional measurements made on two small groups of men and women and on a large group of workmen serve to confirm the equivalence of C/K and (See PDF). The value of the constant ( k) for both men and women is 300. If D represents C/K, then D2 x h = W. Each single circumference ( c) divided by a specific constant ( k), which is a fraction of K, may be converted into a d value and into an equivalent body weight, i.e., d2 x h = d( W). In effect, body weight can be fractionated into at least 11 components which provide quantitative intraindividual and interindividual comparison of body build.

Note:

With the Technical Assistance of Dorothy Merritt Jones and E. Chadwick Squires

Submitted on April 28, 1961
Continuous measurement of alveolo-arterial gradients at ambient and anoxic levels
Authors: Cosby R. S. , Stowell E. C. , Morrison D. M. , Mayo M. , Ruymann F. B. , Bernard B.
Published: December 2017

In 18 normal subjects continuous alveolo-arterial differences were measured at decreasing levels of inspired pO2 from ambient to 12% oxygen. A mean difference of 12.1 mm Hg decreased gradually to virtual obliteration of the gradient at low levels of inspired pO2. A modified Clark electrode lying within a Riley needle continuously recorded arterial O2 tensions and, together with a recording alveolar O2 electrode, inscribed a continuous visual alveolo-arterial difference. The response of arterial pO2 to an anoxic level, though maximal in the 1st min (74% of the total change in 4 min), continued to change at the rate of 2 frac12%/min during and after the 4th min. Continuously changing levels of ventilation and arterial pO2 and pCO2, as described, make it unlikely that the steady state is ever truly present during acute exposure to anoxia.

Submitted on April 17, 1961
Sweating and body temperatures following abrupt changes in environmental temperature
Authors: Belding H. S. , Hertig B. A.
Published: December 2017

Human subjects were transferred between environments imposing different levels of heat stress. Analyses of measurements obtained after a reasonably steady state had been achieved in each of several environments revealed equally good correlation between a) sweat rate and ear temperature (tympanic membrane), and b) sweat rate and calculated deep skin temperature (hypothetical). The correlations are consistent with adjustment of sweating in response to either hypothalamic temperature or temperature of skin receptors or some combination of the two. However, during the first 20 min after transfer, changes in sweat rate and skin temperature occurred together and in the same direction, but were not accompanied by any consistent change in ear temperature. Thus, to the extent that ear temperature represents hypothalamic temperature, an hypothesis of control of sweating based on hypothalamic temperature alone is not tenable. Alternative physiological explanations are given for data developed elsewhere and used in support of an hypothesis of sweat control solely from the hypothalamus.

Submitted on August 14, 1961
Use of respiratory quotients in assessment of aerobic work capacity
Authors: Issekutz B. , Birkhead N. C. , Rodahl K.
Published: December 2017

Oxygen uptake and carbon dioxide output were measured in 32 untrained subjects during exercise on the bicycle ergometer. It was shown that the work respiratory quotient (RQ) under standardized conditions can be used as a measure of physical fitness. ΔRQ (work RQ minus 0.75) increases logarithmically with the work load and maximal O2 uptake is reached at a ΔRQ value of 0.40. This observation offered the possibility of predicting the maximal O2 uptake of a person, based on the measurement of RQ during a single bicycle ergometer test at a submaximal load. For each work RQ between 0.95 and 1.15 a factor was presented, together with the aid of a simple equation, which gave a good approximation (generally better than ±10%) of the maximal O2 uptake.
Effect of altering limb position on blood flow, O2 uptake, and skin temperature
Authors: Abramson David I. , Tuck Samuel , Zayas Agenor M. , Mitchell Roscoe E.
Published: December 2017

The effect of altering the position of the upper extremity on local blood flow, oxygen uptake and tissue temperatures was studied in a group of 19 normal subjects. In each instance the limb was placed in three positions: 1) horizontally, at the level of the heart; 2) with the elbow at this level, but with the forearm and hand dependent and forming an angle of 34°with the horizontal; and 3) with the forearm and hand elevated and forming an angle of 34°with the horizontal. No consistent change in blood flow or O2 uptake was noted when the limb was placed in dependency. In the elevated position there was a small, but significant, reduction in blood flow and O2 uptake. Cutaneous temperature of the forearm was not affected by either position, while a definite fall in skin temperature was noted in the hand in dependency. These results suggest that variations in position of the upper extremity elicit compensatory vascular mechanisms which tend to counteract the hydrostatic effect on local blood flow and O2 uptake.

Submitted on June 19, 1961
Blood and plasma volume in adult males
Authors: Yiengst Marvin J. , Shock Nathan W.
Published: December 2017

Total blood volumes were estimated in 94 normal ambulatory males, aged 19–95 years, by the T-1824 dye dilution method. There were no significant age changes when results were expressed in terms of either body weight or surface area. The mean values for individual age groups between 40'49 and 80'95 years varied between 46.7 ± 1.5 and 51.5 ± 1.5 ml/kg body wt. for plasma volume and between 75.1 ± 2.0 and 82.3 ± 2.0 ml/kg body wt. for total blood volume.

Submitted on October 16, 1961
Maintenance of the pharyngeal airway
Authors: Shelton Ralph L. , Bosma James F.
Published: December 2017

The effect of cervical extension, cervical flexion, mandible displacement, tongue displacement, and effortful increase in intrathoracic pressure on the pharyngeal airway of ten normal adults is described from radiographic observations. Maintenance of the airway is viewed as being effected by interaction between cervical postural and pharyngeal muscles. Identification of the function of these mechanisms might provide new criteria for evaluation of pharyngeal impairment. The performance of extension was especially remarkable because of the consistency of the subjects' postural and pharyngeal responses to spoken command. The pharyngeal airway of each subject was distinctively expanded. The relationship between postural and pharyngeal structures has procedural implications for speech investigations.

Submitted on August 14, 1961
Effect of O2 breathing on pulmonary compliance
Authors: Griffo Zora J. , Roos Albert
Published: December 2017

The effect of oxygen breathing on pulmonary compliance was studied in paralyzed, artificially ventilated dogs and in two normal subjects. 1) In the dogs and the human subjects the course of compliance during oxygen breathing for periods of 1frac12–2 hr following hyperinflation was compared with that during air breathing. 2) In dogs compliance after apnea on oxygen (following hyperinflation) for frac12–7 min was compared with that after apnea on air. Intrapulmonary pressure during apnea was atmospheric. 3) In the human subjects the course of compliance was followed during air breathing for 50–70 min, preceded by hyperinflation and immediately followed by oxygen breathing for 80–100 min. In none of these three sets of studies did oxygen breathing affect the course or magnitude of pulmonary compliance. It is concluded that breathing pure oxygen at atmospheric pressure for several hours does not enhance the development of pulmonary atelectasis in normal subjects.

Submitted on July 3, 1961
Mechanical aspects of panting in dogs
Authors: Crawford Eugene C.
Published: December 2017

Apparently healthy, unanesthetized dogs weighing 12.3 ± 1.8 kg were caused to pant by the warming effect of incandescent lamps. Panting frequency was recorded and found to be 5.33 ± 0.7 cycles/sec. The natural frequency of the respiratory system of each of the animals was then determined, the mean being 5.28 ± 0.3 cycles/sec. The increased effectiveness of panting at the resonant frequency of the respiratory system is discussed in terms of respiratory impedance and maximum volume flow with least effort. The impracticality of panting at other frequencies is shown by calculation.

Submitted on August 2, 1961
Effect of chronic local cold exposure on finger temperature responses
Authors: Adams Thomas , Smith R. Elphin
Published: December 2017

Caucasian subjects from a temperate climate immersed their right index fingers in a stirred ice-water bath for 20 min four times daily for 1 month. During subsequent test immersion, fingers exposed in this way showed an earlier initiation and a more rapid rate of spontaneous rewarming and a higher and more labile final temperature level than did either the same finger before the prolonged cold exposure or other digits not chronically cold exposed. The inference derived from these data that blood flow is elevated in chronically cold-exposed fingers was supported by digital calorimetric determinations. Since finger temperature responses were modified only in the cold-conditioned digit, the term “local cold conditioning” appears justified. Variation of the number of daily exposures made clear a progressive modification of skin temperature responses to cold. During the month of repeated cold exposures, pain associated with this type of cold exposure diminished and finally disappeared. These experimental data parallel most observations on peripheral vascular responses to natural cold exposures and may suggest a mechanism for the changes under both conditions.

Submitted on July 28, 1961
Behavioral consequence of painful electric shock
Authors: Dinnerstein A. J. , Lowenthal M.
Published: December 2017

Choice reaction time and hand steadiness were studied under conditions in which correct performance of a task produced painful electric shock. Task performance deteriorated in response to shock. Deterioration was greater when shock was applied to the active hand than when applied to the passive hand. The hand steadiness test also involved variation in shock intensity and administration of aspirin or placebo. Tremor increased with shock intensity, and aspirin decreased the difference in performance between shock and nonshock trials. The methods employed offer a means of laboratory simulation of disability produced by pathological pain and a possible means of evaluation of analgesic effectiveness.

Submitted on September 11, 1961
Local reactions to air cooling in an Eskimo population
Authors: Miller L. Keith , Irving Laurence
Published: December 2017

Bare hand and facial temperatures in otherwise well-clothed Eskimo men, women, and children were studied during cooling in open air at temperatures between -3 and -7C. Two groups of white men, one composed of individuals accustomed to cold, served for comparison. In contrast to both groups of whites, Eskimo men showed significantly higher minimum finger temperatures, smaller temperature fluctuations during cooling, and higher finger temperatures at termination of exposure. White men less accustomed to cold cooled more rapidly than Eskimo men during initial exposure; white men accustomed to cold cooled at an intermediate rate. Despite an average hand volume less than half that of adult men, Eskimo children maintained finger temperatures as well as white men not accustomed to cold. Two white subjects exhibited a progressively deteriorating type of cooling response in which finger temperatures approached freezing, necessitating early termination of test exposures. Eskimo women reacted in the same manner as Eskimo men. Hand discomfort during cooling was reported absent or minor in adult Eskimos, but was marked in most whites. Eskimo and white adults responded similarly to facial cooling, but cheek temperatures of Eskimo children fell more rapidly.

Submitted on December 26, 1961
Total lung volume and its subdivisions in children: normal standards
Authors: Lyons Harold A. , Tanner Ralph W.
Published: December 2017

Total lung capacity and its subdivisions were determined for 458 apparently healthy school children who ranged in age from 6 to 14 years. Calculations of correlation coefficients for these determinations and height, weight, and body surface area were made. Correlation coefficients were best with height for expiratory reserve volume (boys, 0.821; girls, 0.777), for functional residual capacity (boys, 0.800; girls, 0.801), for residual volume (boys, 0.550; girls, 0.538), for vital capacity (boys, 0.895; girls 0.861), and for total lung capacity (boys, 0.898; girls, 0.975). Inspiratory capacity correlated best with body surface area (boys, 0.881; girls, 0.853). Prediction formulas based on these data were established for total lung capacity and its subdivisions. For total lung capacity the following formulas were found: for boys, 30.71 H + 29.35 W – 2545; for girls, 30 H + 31.31 W – 2536.

Submitted on November 6, 1961
Effect of heat acclimatization on artificial and natural cold acclimatization in man
Authors: Davis T. R. A.
Published: December 2017

The seasonal changes in oxygen consumption, rectal temperature, and skin temperature in response to a 1-hr nude exposure to 14.1 C were measured once monthly in six subjects between October and February. The same measurements were obtained in another group nude exposed 8 hr daily to a chamber temperature of 13.5 C. Shivering decreased as a result of the seasonal and chamber cold exposure ( P < 0.01). Heat production also decreased as a result of both types of exposure ( P < 0.05) but never decreased to basal values. Skin temperature in the seasonal group exhibited no change, whereas a small fall occurred in the chamber group ( P < 0.05). Although no rectal temperature change was demonstrated in the seasonal group, there was a significant fall in the rectal temperature in the chamber group. After the period of chamber and seasonal cold acclimatization, both groups were subjected to 21 days of heat acclimatization followed by another cold-response measurement. In both groups the changes induced by winter exposure and chamber exposure were not influenced by heat exposure. Since previous studies have demonstrated the lack of influence of cold exposure on heat acclimatization, it is concluded that heat and cold acclimatization are not mutually exclusive and can exist simultaneously in man.

Note:

(With the Technical Assistance of D. R. Johnston, F. W. Jacks, and W. Rawlings)

Submitted on October 6, 1961
Cerebrospinal fluid buffering during acute experimental respiratory acidosis
Authors: Swanson August G. , Rosengren Harold
Published: December 2017

Cerebrospinal fluid (CSF) in vitro has less buffering capacity than blood since it lacks serum protein and cellular hemoglobin buffers. However, during acute respiratory acidosis CSF pH falls less than blood pH, indicating a significant in vivo spinal fluid buffering capacity. The nature of this buffering capacity was studied in anesthetized and artificially ventilated cats. Carbon dioxide tensions of 70–75 mm Hg were induced by 7% CO2 breathing. Simultaneous arterial blood and cisternal CSF samples were drawn at 0, 15, 30, 60, and 120 min. pCO2 and bicarbonate were measured with a radiometer AME-1 pH meter and tonometer, using the Astrup technique. A rapid increase in CSF bicarbonate maintained spinal fluid significantly more alkaline than blood throughout CO2 breathing, even though CSF and blood CO2 tensions were nearly equal. Intravenous bicarbonate did not alter CSF bicarbonate significantly during 2 hr. It is postulated that the buffering capacity of spinal fluid increases as a result of diffusion of preformed bicarbonate from brain cells.

Submitted on March 12, 1962
Airflow resistance in lower airway of the dog
Authors: Rossing Robert G.
Published: December 2017

The resistance of the lower airway was measured in dogs by an adaptation of the esophageal-balloon method. In normal dogs resistance was found to be lower than previously reported values and not appreciably changed by flow or volume. In dogs with increased resistance, induced either acutely by pilocarpine inhalation or chronically by repeated exposure to phosgene, resistance decreased with increasing volume. However, resistance was not found to increase with increasing flow, supporting the concept that flow in the lower airway is laminar, at least at the flow rates studied. This changing resistance observed during tidal breathing suggests that a single value for resistance cannot adequately describe the dynamic mechanical behavior of the lung under conditions of increased resistance. The technique described for measuring lower-airway resistance may be useful in the evaluation of the bronchomotor effects of drugs.

Submitted on October 30, 1961
Thermal and metabolic responses of coastal Eskimos during a cold night
Authors: Hart J. S. , Sabean H. B. , Hildes J. A. , Depocas F. , Hammel H. T. , Andersen K. L. , Irving L. , Foy G.
Published: December 2017

Metabolic and thermal studies were conducted at night at Pangnirtung, N.W.T., on a group of ten Eskimo hunters from Cumberland Sound, Baffin Island, and on three white controls, to compare their reactions to cold (5 ± 1 C) with that of other racial groups. Cumberland Sound Eskimos maintained a resting metabolism that was elevated, according to DuBois standards, during sleep on warm nights. This elevation was not found in hospitalized men who had been living for an average of 6 months in Edmonton, Alberta. During exposure to moderate cold, the Cumberland Sound Eskimos and white controls had an elevated metabolism, shivering, and a disturbed sleep. Peripheral temperatures were maintained at a higher level in Eskimos than in whites. Because of the absence of marked physiological differences between Eskimos and whites, it is concluded that the principal adaptation of these Eskimos to their climate is technological.

Submitted on June 4, 1962
Chronic derangements of cerebrospinal fluid acid-base components in man
Authors: Pauli H. G. , Vorburger C. , Reubi F.
Published: December 2017

In a group of normal subjects a relative respiratory acidosis in the cerebrospinal fluid (CSF) as compared with arterial blood was found. There was no significant gradient for bicarbonate concentrations between the two compartments. In normal subjects under high-altitude adaptation, arterial and CSF respiratory alkalotic shifts were similar. A concomitant fall in bicarbonate levels was slightly less in CSF than in arterial blood. In a group of patients with uremic acidosis the arterial-cerebrospinal H ion gradient was reversed, as bicarbonate was significantly less reduced in CSF relative to arterial blood. Hemodialysis led to restitution of the relative respiratory acidosis in CSF. These findings seem to indicate fast diffusion of CO2 across the cerebrospinal-arterial barrier. In contrast, diffusion of bicarbonate and/or H ion appears to be delayed and incomplete. CSF acid-base components are not likely to correlate with stimulation of the respiratory centers under these conditions.

Submitted on March 12, 1962
A physiological criterion for setting thermal environmental limits for everyday work
Authors: Lind A. R.
Published: December 2017

Three subjects walked continuously on a treadmill for periods of 1 hr or more at 180, 300, or 420 kcal/hr in a range of cool and hot climates from corrected effective temperature (CET) 10–32 C. At each rate of work rectal thermal equilibrium was practically independent of the influence of environment over a wide range of climates (“prescriptive” zone); the upper limit of the prescriptive zone appeared to be associated with the minimal bodily thermal gradient compatible with the transfer of adequate amounts of heat from the core to the periphery without placing the thermoregulatory system under disproportionately increased strain, in terms of circulatory response and elevated body core temperature; as such, this seems to be one possible criterion by which thermal environmental limits for everyday work may be assessed. The upper limits of prescriptive zones for work at an energy expenditure of 300 kcal/hr is CET 27.4 C and those for the lower and higher rates of work, respectively, were CET 30.2 C and 26.9 C.

Submitted on June 15, 1962
Cardiogenic oscillations as an index of pulmonary blood flow distribution
Authors: Fowler K. T. , Read John
Published: December 2017

A relationship has been developed between the amplitudes of cardiogenic oscillations of expired gas tensions and the ratio of blood flows through upper and lower zones of the erect human lung. Instrumental methods have been devised for the accurate measurement of the amplitudes of these oscillations. A theoretical and experimental study was made of the sources of error. The ratio of upper- to lower-zone blood flow could be determined with a reproducibility of ±20% so that changes in this ratio of greater than 20%, attendant upon a stimulus, could be identified.

Submitted on July 16, 1962
Solubility of carbon dioxide in serum from 15 to 38 C
Authors: Austin William H. , Lacombe Eleanor , Rand Peter W. , Chatterjee Manu
Published: December 2017

The solubility of carbon dioxide in serum has been determined from 15 to 38 C. Consideration was given to the water, lipid, protein, and electrolyte composition of the serum which influences the solubility. It was concluded that the direct determination of the solubility of carbon dioxide in serum yields significantly different values from those extrapolated from 38 C based on an assumed parallel relationship between serum and water. New solubility factors and pK's have been calculated from this information.

Submitted on July 5, 1962
Slowing of the heart at the beginning of exercise
Authors: Craig F. N. , Cummings E. G.
Published: December 2017

At 18 C the heart began to beat faster at the beginning of treadmill exercise. In the first 10 beats, the average increase above the previous standing rate amounted to 12 beats/min in walking and 28 beats/min in running. At 38 C or when atropine was injected, the standing rate before exercise was rapid; in the immediate response to exercise, the rate increased less than at 18 C without atropine, remained the same as in standing, or decreased temporarily below the standing rate by as much as 40 beats/min. These early responses were attributed to changes in vagal inhibition. After the start of the run there was a secondary increase between the 25th and 60th sec that averaged 22 beats/min at the peak of the response to atropine. This secondary increase was attributed to accelerator activity.

Submitted on August 27, 1962
Artificial acclimatization of women to heat
Authors: Hertig B. A. , Belding H. S. , Kraning K. K. , Batterton D. L. , Smith C. R. , Sargent Frederick
Published: December 2017

Acclimatization to heat, repeatedly demonstrated in male subjects, has not been reported in females. This paper presents quantitative evidence for heat acclimatization in women. Nine women participated (five at University of Pittsburgh and four at University of Illinois, Urbana) in daily 2-hr walks in the heat for 2–3 weeks. By the usual criteria (reduced pulse rate, reduced rectal temperature rise, lower skin temperature, ability to complete the assigned task, and subjective comfort) all subjects became acclimatized to heat.

Submitted on September 4, 1962
Relationship between fractions of the Q-T interval
Authors: Simonson Ernst , Cady Lee D. , Woodbury Max
Published: December 2017

In 100 healthy men from 40 to 59 years of age, the regressions and correlations between the R-R, Q-T, QRS intervals, S-T segment duration, and T-wave duration were determined by means of computer analysis. The range of heart rate was from 45 to 115 beats/min, with equal distribution of the samples in four ranges of heart rate (45–60, 60–70, 70–80, 80–115). The error of measurement of the S-T duration was determined from independent repeat measurements of one observer and observer variation from measurements of two observers. The regressions of all interval fractions on heart rate are linear. The correlation of the R-R interval and of the Q-T interval with all fractions except the QRS interval is highly significant. The major contributing factor to the slope of the Q-T interval versus heart rate is the duration of the S-T segment. A table with the fiducial normal limits for evaluation of interval changes in individual patients is given.

Submitted on November 16, 1962
Relation between work output of respiratory muscles and end-tidal CO2 tension
Authors: Milic-Emili J. , Tyler J. M.
Published: December 2017

End-tidal CO2 tension, pulmonary ventilation, and work output of respiratory muscles were determined in six normal subjects breathing various mixtures of carbon dioxide in air, with three graded resistances added to both inspiration and expiration. In two individuals, the resistances were also added separately to inspiration or expiration. A linear relationship was found between work output of inspiratory muscles and end-tidal CO2 tension; this relationship was uninfluenced by added resistance. No consistent relationship was observed between either ventilation or work output of expiratory muscles and end-tidal CO2 tension. These results suggest that carbon dioxide controls directly the activity of inspiratory muscles alone and that the activity of expiratory muscles is only coincidentally involved. The possible role of intrinsic properties of respiratory muscles and of nervous mediation in the control of breathing is discussed.

Submitted on October 22, 1962
Alveolar-arterial oxygen tension gradient due to diffusion
Authors: Staub Norman C.
Published: December 2017

This is a theoretical paper in which the absolute time course of O2 uptake by the red blood cells during their passage through the pulmonary capillaries is calculated from recently obtained values of thetaO2 (the rate of O2 uptake by human red cells per milliliter of blood as a function of O2Hb saturation), the components of diffusion resistance (alveolar-capillary membrane and instantaneous pulmonary capillary blood volume), and the pulmonary blood flow. One result of these calculations is the alveolar-arterial Po2 difference due to diffusion. Five situations of varying degrees of diffusion stress are examined. The diffusion gradient for O2 is generally smaller than that computed by older techniques. Most of the diffusion resistance lies in the blood in normal subjects at rest breathing air. If the membrane and blood components of the diffusion resistance are unevenly distributed in the lung, the diffusion gradient will be greater than the ideal values. Regional variations in capillary transit time for any reason are more serious than membrane variation because of higher diffusion resistance of the blood normally.

Submitted on November 19, 1962
Effect of postburn serum on in vitro respiration of normal myocardium
Authors: Spector Arthur A.
Published: December 2017

An in vitro respiratory system using normal guinea pig left ventricular myocardium is described. QO2 values are given for this preparation incubated with representative substrates. A larger elevation in oxygen consumption is seen with linoleic acid as compared to other unesterified fatty acids tested. Serum obtained from dogs before and 15 min after flash burn was incubated with this heart slice system. No differences in oxygen uptake are noted between addition of control and postburn serum. No major serum enzymatic or chemical alterations are found at 15 min postburn. Plasma protein electrophoretic patterns remain unchanged at 15 and 40 min after injury. These results do not support the concept that the cardiac defect in early burn shock is caused by a circulating substance that either inhibits oxidation or uncouples oxidative phosphorylation by the myocardium.

Note:

(With the Technical Assistance of Ralph A. Abreo and Raburn Jackson)

Submitted on November 15, 1962
Heart rate responses to apneic underwater diving and to breath holding in man
Authors: Craig Albert B.
Published: December 2017

Bradycardia is a response to apneic diving which man has in common with many other species. Slowing of the heart rate during diving was observed in children as well as adults and was as prominent in poor swimmers as in those subjects who were familiar with the water. The response was independent of depth down to 27 m, but could not be produced by simulated dives in a compression chamber. Diving in water implies several maneuvers, some of which were investigated during breath holding. It was observed that the tachycardia produced by breath holding at different Valsalva pressures was proportional to the increase of intrathoracic pressure. At equal pressures the tachycardia was less when the subject was in water than when in air. Other maneuvers which increased venous return at the beginning of the breath hold produced a bradycardia during the apnea, and conversely when venous return was impaired there was a tachycardia. The hypothesis is presented that diving bradycardia in man might be explainable in terms of already known physiological mechanisms.

swimming; submersion

Submitted on February 27, 1963
Ventilatory response to inspired carbon dioxide in infants and adults
Authors: Avery Mary Ellen , Chernick Victor , Dutton Robert E. , Permutt Solbert
Published: December 2017

A rebreathing method was used to study the increase in ventilation with an increase in PaCOCO2 in newborn infants and adults. The response curve of infants was shifted to the left of that of adults, which is consistent with their lower initial PaCOCO2 and buffer base, and greater metabolism per kilogram of body weight. The rebreathing response curves of infants were also to the left of steady-state responses reported by others. It is postulated that nonchemical stimuli caused higher ventilation throughout the entire range of the CO2 response curves in the infants studied by rebreathing without altering the sensitivity to increases in Pco2. The change in ventilation per kilogram versus the change in PaCOCO2, the slopes of the CO2 response curves, were nearly the same in infants and adults studied by either method. This finding, when the comparison is made on the basis of body weight, suggests the sensitivity of the regulatory apparatus does not change with age, and the output of the effector apparatus, lungs and chest wall, is related to the mass of the individual.

CO2 response curves; nonchemical stimuli; chemical stimuli; respiration

Submitted on February 19, 1963
Effects of differential housing and stress on diet selection, water intake, and body weight in the rat
Authors: McDonald David G. , Stern John A. , Hahn William W.
Published: December 2017

Animals were divided into three groups: group-housed, standard laboratory diet; group-housed, self-selection diet; individually housed, self-selection diet. After adaptation to diets, animals were observed during periods of restricted (1 hr/day) feeding, cold stress (with restricted feeding maintained), recovery from cold stress, and recovery from restricted feeding, in that order. Measures recorded were body weight and food and water intake. Differential effects of the procedures on each of the groups were evaluated, and it was concluded that individually housed animals were generally less adaptable to the experimental procedures. Several hypotheses on the effects of individual housing are discussed.

cold stress; food deprivation; group vs. individual; housing; environmental adaptation; self-selection diet

Submitted on January 23, 1963
Glass electrode measurements of blood sodium and potassium in man
Authors: Friedman Sydney M. , Wong Shek-Leung , Walton John H.
Published: December 2017

A practical, simple procedure for the estimation of (Na+) and (K+) in undiluted whole blood or serum is presented. The method uses cation-responsive glass electrodes and is based on a graphic simplification of equations and on calibration steps for deriving the necessary constants. When one electrometer is used, the procedure requires about the same time as standard flame photometry; with two electrometers, it is faster. Values for (Na+) and (K+) in our series of 38 normal young adults compare well both absolutely and in terms of variability with recently published flame photometric measurements in protein-free samples. In a random series of hospital patients, occasional striking divergences suggest that ion binding as a factor in disease warrants further investigation.

blood cation activity; electrolytes in man

Submitted on March 21, 1963