bluuebunny/crossref_metadata_2025_split huggingface dataset:
A technique for differential photoelectric plethysmography of brain and ear
Authors: Heck Albert F. , Hall Verlan R. 
Published: December 2017

A technique for implantation and apparatus for obtaining a circulatory pulse volume wave from the surface of the cerebral cortex of animals in both acute and chronic experimental situations are described. Fiber optic light guides are placed through burr holes on the brain surface and the skull closed with cement, thus restoring the Munro-Kellie principle. Heatless light is conducted into the brain and changes in optical density of this tissue due to vascular pulsation are converted to wave forms by a photoelectric pickup. Trauma and tissue reaction are minimal. Attachment of a similar plethysmograph to the ear by means of Teflon button receptacles allows differential recording of plethysmograms from either vascular bed. fiber optics; photoelectric technique; Munro-Kellie principle Submitted on March 5, 1964
Lung volume and ventilatory response to airway obstruction during treadmill exercise
Authors: Tabakin Burton S. , Hanson John S. 
Published: December 2017

Measurement of lung volumes and certain ventilatory variables during treadmill exercise with a 5-mm expiratory airway obstruction revealed significant changes in residual volume, expiratory reserve volume, and lung clearance index as compared to values obtained without obstruction. These variations in themselves do not explain previously observed large decrements in oxygen utilization with acute airway obstruction. However, the additive effects of decreased alveolar ventilation and alterations in intrapulmonary gas distribution could account for this phenomenon. expiratory airway obstruction; lung volume changes with airway obstruction; decreased oxygen utilization with resistance breathing; treadmill exercise and resistance breathing; ventilatory alterations with obstructed expiration Submitted on April 19, 1963
Criteria for physiological limits for work in heat
Authors: Wyndham C. H. , Strydom N. B. , Morrison J. F. , Williams C. G. , Bredell G. A. G. , Maritz J. S. , Munro A. 
Published: December 2017

New physiological criteria are put forward for setting the limits for men at work in hot conditions. They are based upon the fact that the curves relating rectal temperatures to conductances and rectal temperatures to sweat rates have two components. One is where the increases in the sweat rates and conductances, with rise in rectal temperature, are relatively large, i.e., there is a “sensitive” range of control; the second is where the curves of sweat rates and conductances against rectal temperatures reach asymptotes, i.e., become “saturated.” The upper limit of the sensitive range is a rectal temperature of 100.5 F (38.1 C), and the saturated range begins at rectal temperatures of 102.5 F (39.4 C). These concepts explain the “easy,” “difficult,” or “excessive” ranges of conditions of the Fort Knox and Human Sciences Laboratory studies. The great advantage of these criteria over others proposed is that the extent of the physiological strain on the workmen can be assessed, directly and simply, by a measurement of oral or rectal temperatures during the shift, and from these results limits for work can be set for work at specific hot jobs. assessment of the extent of physiological strain on workmen in heat; determination of physiological limits for work in hot conditions; sensitive and saturated control ranges in man's temperature regulation; relationships between rectal temperature and conductance and rectal temperature and sweat rate Submitted on March 20, 1964
Effects of immersion of the hand in cold water on digital blood flow
Authors: Hsieh A. C. L. , Nagasaka T. , Carlson L. D. 
Published: December 2017

The temperatures of the tip of the middle fingers ( Ts) of nine comfortably warm subjects have been recorded during immersion of all the fingers of one hand in a 27–liter bath containing slowly stirred water at temperatures ranging from 4.6 to 40 C ( Tw). Blood flow ( F = ml/cm2 per min) was estimated from the average Ts for the last 15 min of a 20-min period, Tw and body temperature ( Tb) by using the equation: F = 1,087 x K( Ts – Tw)/ ( Tb – Ts). (K = 0.0134 kcal/cm2 per min per °C.) The increase in F per °C reduction in Tw below 10 C was 0.16 ± 0.077 (P < .05). This value gives a measure of the vasodilatation occasioned by immersion in water below 10 C. The sample regression equation of F on Tw was: F = 4.1 – .16 Tw ± 0.17 (n = 27; range of Tw = 4.6 to 10 C). This method of estimating blood flow at several levels of Tw describes more fully the peripheral circulatory response to cold than methods in which only one level of Tw is used. cold-induced vasodilatation; temperature and finger blood flow Submitted on August 28, 1963
Tolerance of men working in hot, humid environments
Authors: Iampietro P. F. , Goldman R. F. 
Published: December 2017

Tolerance of acclimatized men working in eight hot, humid environments was studied. Results show that the upper limits for completion of 3 hr of work at a caloric expenditure of 350 kcal/hr are dry bulb (DB) 95 F and wet bulb (WB) 90 F. Rectal temperature is not a good indicator of tolerance under the conditions of our study, while skin temperature and heart rate are. A good relationship is evident between the rapid changes in skin temperature during work (first 10 min of exposure) and tolerance time; thus, these rapid changes may be used to predict tolerance time. Of the physical indexes of thermal stress the best relationship was established between WD (WD = 0.15 DB and 0.85 WB) and tolerance time. body temperature; tolerance to heat; tolerance to humidity; skin temperature; temperature regulation Submitted on June 8, 1964
Pulmonary hemodynamics and arterial oxygen saturation in pulmonary embolism
Authors: Caldini Paolo 
Published: December 2017

Thoracotomized dogs with a reservoir and mechanical pump substitution of the right heart were subjected to pulmonary embolization by repeated injection of glass microspheres (80-120 뀅) or autologous clots (2-3 mm). Airway pressure was controlled by means of a Starling resistor connected to the expiratory line of the respirator. Following embolization with microspheres, the initial abrupt rise in pulmonary arterial pressure was followed by a more gradual increase, interpreted as due to delayed constriction of pulmonary vascular bed. Following emboli injection, systemic arterial oxygen saturation decreased to 82%, venous admixture rose to 30%. When the end-expiratory pressure was increased from 5 to 20 cm of water, the arterial oxygen saturation rose and venous admixture decreased to values not significantly different from pre-embolic levels. These findings suggest that pulmonary hypertension in pulmonary embolism is due not only to a mechanical obstruction of pulmonary vessels, but that some degree of pulmonary vasoconstriction also occurs when small-sized emboli are used. Arterial hypoxemia associated with pulmonary embolism appears to be due to perfusion of non- or poorly ventilated areas of the lung and not to significant blood flow through arteriovenous anastomoses. blood tensions; pulmonary edema; pulmonary venoarterial shunts Submitted on May 4, 1964
Fetal respiratory movements in response to rapid changes of CO2 in carotid artery
Authors: Avery Mary Ellen , Chernick Victor , Young Maureen 
Published: December 2017

Recent studies have suggested that chemoreceptors may respond to the rate of change of carbon dioxide as well as its level in arterial blood. The blood which perfuses the carotid body of the fetus would be expected to have less cyclic changes in blood gases since the placenta is the organ of gas exchange. The absence of oscillations in blood gases may contribute to the lack of sustained respiratory activity in utero. Slow changes in fetal blood gases do not initiate fetal respiratory activity. Rapid infusions of blood equilibrated with high CO2 mixtures into the carotid artery of exteriorized fetal guinea pigs and a lamb were associated with gasps. It is proposed that the initiation of rhythmic breathing at birth may depend in part on the oscillations in CO2 which follow use of the lung as the organ of gas exchange. oscillations, Pco2; first breath; chemoreceptors Submitted on July 20, 1964
Secondary ventilatory response to exercise: modification by agents which alter CBF
Authors: Krumholz Richard A. , Ross Joseph C. 
Published: December 2017

Ventilation increases at the onset of exercise. Another abrupt increase, the secondary ventilatory response, occurs later. This study gives further observations on the secondary ventilatory response and its modification by O2 breathing and other agents which alter cerebral blood flow. The secondary ventilatory response is similar to the response which follows release of arterial tourniquets inflated on the thighs, which is delayed in time of onset by O2 breathing and infusion of aminophylline and NH4Cl and accelerated by CO2 breathing and NaHCO3 infusion. This suggested that the respiratory center response may, to some extent, be dependent upon cerebral blood flow. The onset of the secondary ventilatory response was delayed by 100% O2 breathing. Infusion of NH4Cl significantly delayed the onset of the secondary rise and NaHCO3 tended to make it come sooner. The timing of the secondary ventilatory response, then, was changed by substances which alter cerebral blood flow. It is suggested that the secondary ventilatory response may be due to a blood-borne substance released from working muscles. regulation of breathing; cerebral blood flow and respiratory center responses Submitted on January 10, 1964
An experimental chamber for long-term studies of chronic hypoxia in small animals
Authors: Sulkin Norman M. , Jones George 
Published: December 2017

An experimental chamber was designed in which chronic hypoxia, as well as adaptation to hypoxia, could be studied over prolonged periods of time in 36 or more small laboratory animals. Rats have been kept in this chamber for periods up to 90 days with oxygen levels from 21% down to 3%, the percentage of oxygen being controllable to 0.25%. The chamber is temperature controlled and maintains a constant relative humidity which may be predetermined. Oxygen levels are maintained by adjusting input of air and nitrogen. The nitrogen tanks are attached to an automatic manifold control which maintains a constant flow of nitrogen even while nitrogen tanks are being changed. It is practical to have a bank of six to eight nitrogen tanks attached to the manifold. Such a bank of nitrogen tanks may last from 4 to 12 days depending on the percentage of oxygen desired. The percentage of oxygen in the chamber is measured directly by means of an oxygen analyzer. apparatus for producing chronic hypoxia; automatic system for studying hypoxia; temperature and humidity control for small animals Submitted on June 29, 1964
A comparison of concentric, eccentric, and isometric strength of elbow flexors
Authors: Doss Wayne S. , Karpovich Peter V. 
Published: December 2017

A method was developed for a continuous and simultaneous recording of maximum muscle force of the elbow flexors and the degrees of the elbow angles during isotonic contractions. Both concentric and eccentric movements were used. The data thus obtained were compared with the flexors' force measured during isometric contractions at similar angles. It was found that eccentric force was 13.5% greater than isometric force and 39.7% greater than concentric force. force during movement; isotonic continuous force; electrogoniometer; force, maximum Submitted on April 6, 1964
Thermoregulation and cold acclimation in a hibernator, Citellus tridecemlincatus
Authors: Pohl Hermann , Hart J. Sanford 
Published: December 2017

In the thirteen-lined ground squirrel, Citellus tridecemlineatus, the maintenance of body temperature and oxygen consumption in the cold is improved by acclimation to 18 and 6 C in the laboratory. Heat production at -30 C was greater in animals acclimated to 6 C, whether or not they had been previously hibernating, than in squirrels kept at 28 C. Oxygen consumption was correlated to body weight0.41. This relationship was not significantly affected by changes in ambient temperature. Local heat flow from the dorsal thorax was similar at a given temperature in all acclimation groups but the thermal conductance was greater and the cardiac-subcutaneous temperature difference was smaller in squirrels acclimated to 6 and 18 C. Although shivering was equally high in warm- and cold-acclimated ground squirrels in the cold, nonshivering thermogenesis occurred in curarized cold-acclimated animals exposed to cold or injected with noradrenaline. The results of the study suggest that ground squirrels are regularly exposed to temperatures in their natural habitat which induce considerable cold acclimation. oxygen consumption—heat production; body temperature—heat conductance; muscular activity Submitted on July 6, 1964
Acclimatization of older men to work in heat
Authors: Robinson Sid , Belding H. S. , Consolazio F. C. , Horvath S. M. , Turrell E. S. 
Published: December 2017

Four men, ages 44—60, repeated daily work experiments in the heat by which they had demonstrated on themselves rapid acclimatization to work in a hot climate 21 years earlier. The work, heat stress, and duration of exposure were those originally found to cause marked hyperpyrexia and circulatory strain in unacclimatized men (mean age 31 years) on the 1st day in the heat. Under these conditions, the subjects sweated at 1.3— 1.5 kg/hr. Tolerance of the men on the 1st day of exposure was no less than when they were younger. Body temperatures and heart rates of the older men were lowered in successive days of exposure and the work was judged progressively easier. Final values of body temperature reached after 5—7 days of exposure were about the same as observed originally after the same number of exposures. Thus, these older men exhibited about the same degree of strain during work in the heat as they did 21 years earlier and acclimatized about as well. aging; hyperthermia Submitted on October 1, 1964
Blood serum enzyme activity of dogs exposed to heat stress and muscular exercise
Authors: Bedrak E. 
Published: December 2017

The activity of several clinically important enzymes was determined in 11 Alsatian dogs exercised in a temperate environment, exposed to heat stress alone, and exercised in a hot environment before and after heat acclimatization. Enhanced activities of glutamic oxalacetic transaminase (GOT) (P < 0.01), glutamic pyruvic transaminase (GPT) (P < 0.05), lactic dehydrogenase (LDH), phosphohexose isomerase (PHI) (P < 0.05), acid phosphatase (ACP), alkaline phosphatase (ALP), aldolase (ALD), and lipase (LIP) were observed in all dogs exposed to the various physiological stresses. The alteration in enzyme activities of acclimatized dogs was generally smaller than in nonacclimatized animals. Comparison between the two control groups (heat acclimatized versus nonacclimatized) indicates a significant increase in LDH activity (P < 0.01) and lower activities of PHI (P < 0.05), ACP (P < 0.05), and ALP (P < 0.01) in heat-acclimatized dogs. blood serum enzymes in acute stresses; muscular exercise in a hot environment; nonacclimatized dogs; heat-acclimatized dogs Submitted on August 17, 1964
Functional blood volume and distribution of specific blood flow in the kidney of man
Authors: Gómez Domingo M. , Demeester Michel , Steinmetz Philip R. , Lowenstein Jerome , Sammons Billy P. , Baldwin David S. , Chasis Herbert 
Published: December 2017

A method has been devised to determine the distribution of blood flow through the kidney in man and animals. The studies reported here have been accomplished in humans by using catheterization of renal artery and vein so as to administer a dye indicator at the entrance of the system and measure its behavior at the exit. Through a transformation of the equation of the dye curve the distribution of specific blood flow is inferred. The distribution function seems to be superimposable from one individual to another. The ratio of the half width to the first moment of the distribution function remains nearly constant under widely variable physiological conditions. Renal blood volume and renal capillary surface area are also measured. specific renal blood flow; functional renal blood volume; renal blood volume; capillary blood volume; renal capillary surface area Submitted on October 9, 1964
Fetal and maternal temperatures in rabbits
Authors: Hart Frederick M. , Faber J. Job 
Published: December 2017

The differences between fetal deep body temperature and maternal aortic temperature were measured in 10 New Zealand white rabbits of 22—29 days gestation with thermocouples thrust into the fetuses immediately after the animals had been killed by a warmed overdose of sodium pentobarbital. Fetal temperatures exceeded maternal temperatures by —2.51 + 0.099.X °C, where X is the gestational age in days. There is 95% confidence that fetal temperatures exceeded maternal temperature by at least 0.25 °C at a fetal age of 29 days. Permanently implanted thermocouples in six nonpregnant rabbits showed that the ventral surface of the abdominal cavity is colder than the aorta, and that the dorsal surface is slightly warmer. Fetal heat loss is partly via the umbilical circulation and partly via the fetal body surface. tissue temperatures in rabbits; fetal heat loss Submitted on September 28, 1964
An improved system for prolonged exposure of small animals to artificial low pressures
Authors: Kollias James , Jordan John Patrick 
Published: December 2017

A system has been developed for exposing small animals to a low pressure-high oxygen environment. Several unique features such as 1) pressure control, 2) an electronic watering device, and 3) a constant environmental temperature are discussed. artificial environment; high altitude; high oxygen; watering device Submitted on July 24, 1964
Change in oxygen tension of shed blood at various temperatures
Authors: Eldridge Frederic , Fretwell L. Kent 
Published: December 2017

The change in oxygen tension (pO2) of shed blood was determined polarographically for 2 hr after shedding at temperatures of 37.5, 22—24, and 1 C. The results show that blood pO2 decreases progressively after shedding, that the decrease is especially marked in blood of high initial pO2 values, and that cooling of the sample slows but does not stop the metabolic processes leading to oxygen utilization. The results reaffirm the need for rapid analysis of blood for pO2. polarographic pO2 analysis; temperature effect; blood metabolism Submitted on March 6, 1964
Effects of aspirin on detection and tolerance of electric shock
Authors: Dinnerstein Albert J. , Blitz Bernard , Lowenthal Milton 
Published: December 2017

Most studies of the effects of aspirin on laboratory-induced pain in humans have shown no effect. A few studies showed analgesic effects. Previous work by the present authors, using indirect measures of pain intensity, showed aspirin to often increase rather than decrease the effects of a noxious stimulus. The present study, employing electric shock and 600 mg of aspirin, examined shock detection and pain thresholds, judgments of discomfort, and the maximum tolerated voltage. Aspirin had little or no effect on most subjects. In a large minority of subjects, aspirin produced a highly reliable increase in sensitivity to shock. These results can be reconciled with the clinical use of aspirin as well as with conflicting laboratory results. Methodological issues are raised concerning this domain of investigation. pain; analgesia; anxiety Submitted on December 18, 1964
A strain-gage platform for force measurements
Authors: Petersen W. A. , Brookhart J. M. , Stone Solon A. 
Published: December 2017

Design, construction and performance characteristics are described for a rugged, compact, linear force transducer using strain gages as the sensing elements. The device is adaptable to a variety of weighing or force-measurement tasks in the laboratory. weight measurement; mass measurement; force transducer; weight transducer; load cell Submitted on November 13, 1964
Cardiovascular and sweating responses to water ingestion during dehydration
Authors: Senay Leo C. , Christensen Margaret L. 
Published: December 2017

The experiments reported are concerned with cardiovascular and sudomotor events preceding, accompanying, and following ingestion of water by five dehydrating subjects 8.75 hr after entrance into a heat chamber (43.3 C DB, 29 C WB). Certain skin areas such as the cheek showed increases in evaporative heat loss before subjects came in contact with water. This reflex could be initiated by saline ingestion but the degree of skin and oral temperature changes appeared to depend on tonicity of fluid ingested. The gustatory reflex was not thought to be the initiating agent for sudomotor responses. Increases in cutaneous blood flow appeared to begin almost as promptly as sweating responses but took considerably longer to develop. Ingestion of saline, though initiating a sweating response, did not alter heart rate, blood pressure, or cutaneous blood flow. It is suggested that fluid ingestion, regardless of tonicity, triggers reflex sweating over the body surface. Intensity and duration of this sudomotor response, as well as initiation of cardiovascular changes, apparently depend on tonicity of ingested fluid. cutaneous blood flow; skin temperature; regional sweating Submitted on November 27, 1964
Pulmonary diffusing capacity and capillary blood flow during forward acceleration
Authors: Power Gordon G. , Hyde Richard W. , Sever Raymond J. , Hoppin Frederic G. , Nairn Jean R. 
Published: December 2017

We studied possible causes of the decreased arterial oxygen saturation seen when a subject is accelerated in a centrifuge by measuring simultaneously the pulmonary diffusing capacity, DlCO, and the effective pulmonary capillary blood flow, Qc, using breath-holding techniques with carbon monoxide and acetylene. After 1 min of forward ("eyeballs in") acceleration at eight times normal gravity, 8 G, average Dl decreased 35% from an initial control of 33.7 to 21.5 ml/(min x mm Hg) in four subjects. Although this decrease was statistically significant, the values observed were not low enough to indicate that impaired diffusion was a prime cause of arterial unsaturation. Average Qc decreased 35% during acceleration from an initial control value of 12.9 to 8.2 liters/min, also a significant change. These values may have indicated that total pulmonary blood flow was reduced, but a more likely explanation is that a large portion of pulmonary flow perfused nonventilated regions. Dl and Qc returned toward initial control levels within 8 min after acceleration in most instances. lung volume during acceleration Submitted on March 1, 1965
Deep diving and short decompression by breathing mixed gases
Authors: Keller H. , Bühlmann A. A. 
Published: December 2017

A series of test dives carried out by 14 subjects in depths between 130 and 1,000 ft. for periods varying between 5 min and 2 hr revealed that changes of the inert gas in the breathing mixture permit a considerable shortening of the decompression time. The physical and physiological basis of the method is discussed. physiological properties of He, N2, and Ar related to molecular weight and solubility; differences in diffusion rate and saturation speed of He, N2, and Ar Submitted on January 18, 1965