bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bio-assay for antidiuretic activity in blood of undisturbed rats
Authors: Little John B. , Radford Edward P. 
Published: December 2017

In order to study circulating antidiuretic hormone (ADH) levels in rats unaffected by anesthesia or manipulation, a method is presented whereby blood samples may be obtained through an indwelling aortic catheter without disturbing the animal. An intravenous rat bio-assay for ADH is described which is sensitive to absolute doses of 2–3 microunits U.S.P. posterior pituitary standard. To obtain maximum sensitivity and reliability no surgical procedure was performed on the assay rat on the day of assay, as we have found that despite alcohol anesthesia ADH release may still be stimulated in assay animals. With 0.5-ml plasma samples injected into two assay animals simultaneously, ADH activity as low as 4μU/ml plasma could be reliably detected. Antidiuretic activity of plasma from undisturbed rats was generally below 4 μU/ml, but when ether anesthesia was used plasma levels were highly variable though generally markedly increased. In animals dehydrated for 1–3 days plasma levels averaged 14.6 μU/ml. These values are considerably lower than concentrations previously reported for rats, and the difference suggests the importance of minimal disturbance to the donor animal when blood is obtained. The low plasma levels we have observed in dehydrated rats are nevertheless above the level calculated to produce maximum antiduresis. ADH determination in circulating blood; vasopressin bio-assay; ADH in rat plasma; ADH levels in undisturbed rats Submitted on August 19, 1963
Role of hydrochloric acid in iron absorption
Authors: Jacobs Peter , Bothwell Thomas , Charlton Robert W. 
Published: December 2017

The absorption of 5 mg iron administered in 300 ml water was compared with absorption from 300 ml 0.05 n HCL in 24 subjects with histamine-fast achlorhydria, using a double isotope technique. In ten individuals given ferric chloride the mean absorptions were 2.2% with water and 9.2% in acid; the difference was less marked in the case of the seven subjects to whom ferrous ascorbate was administered (10.9% and 19.3%, respectively). In contrast, acid did not increase the absorption of hemoglobin iron, the mean figures being 13.4% with water and 9.6% with HCL. pernicious anemia; achlorhydria; gastric pH Fe55 and Fe59; radioactive hemoglobin iron Submitted on June 17, 1963
Estimation of tissue elasticity of the lung
Authors: Carton Robert W. , Clark John W. , Dainauskas John , Barron Arnold 
Published: December 2017

Theoretical work-volume curves for liquid-filled lungs were constructed based on an assumed geometric form and deformation of the terminal air spaces and on the characteristics of single fibers of elastic tissue. These curves were compared with those measured in rats and with one taken from the journal literature in the case of a human lung. The form of the measured curves fitted the theoretical curves. The assumptions necessary were considered in detail. In both species more elastic tissue has been found present in the lung than would be expected theoretically. The action of additional restraining elements was thought necessary at high volume. pulmonary pressure-volume curves; pulmonary work-volume curves; lung volume and elastic tissue mass; pulmonary elastic tissue; tissue elasticity; pulmonary mechanics Submitted on April 22, 1963
Saturation of arterial blood with oxygen during maximal exercise
Authors: Rowell Loring B. , Taylor Henry L. , Wang Yang , Carlson Walter S. 
Published: December 2017

The per cent saturation of the arterial blood with oxygen was examined in four men before and during the last 15 sec of a 3-min run of sufficient intensity to elicit a maximal oxygen intake. The measurements were repeated after a 3-month period of intensive conditioning for middle distance running and in a group of four athletes in good physical condition. The per cent saturation in the sedentary group was 95.8 at rest and 93.4 during exhausting exercise; after conditioning the similar figures were 95.4 and 91.4 and, finally, the athletes showed a per cent saturation of 85.2 during the heavy work. The arterial oxygen content during exhausting work was found to be 20.12 ml/100 ml blood in the sedentary group before training, 19.02 after conditioning, and 18.18 in the group of athletes. It is concluded that, in athletes who are well conditioned and pushing themselves close to the limit of their capacity, arterial desaturation can take place. athletic conditioning and arterial oxygen saturation; arterial desaturation in athletes; ventilation and arterial desaturation; oxygen intake and arterial oxygen saturation Submitted on August 5, 1963
An ultramicro oxygen electrode
Authors: Fatt Irving 
Published: December 2017

The advantages of a 1-μ-diameter platinum cathode in the Clark-type oxygen electrode are shown to be freedom from effects due to flow, stirring, or mechanical pressure. When used with a 5-mil polyethylene membrane the 1-μ electrode shows only a 2% difference between a vigorously stirred solution and the unstirred solution. A mechanical pressure of 200 psi on the 1-μ covered electrode caused only a 20% reduction in current. The use of a 1-μ covered electrode as an implant is suggested. electrode implant; Clark-type oxygen electrode modification; polarographic electrode; oxygen measurement; platinum electrode Submitted on March 4, 1963
A method of recording from single muscle fibers or motor units in human skeletal muscle
Authors: Pierce Donald S. , Wagman Irving H. 
Published: December 2017

It is possible to record single muscle fiber and single motor unit potentials with a tungsten microelectrode inserted percutaneously (without discomfort) into human muscle. Potentials averaging 10–12 mv, 2–4 msec in duration, have been recorded from such muscles as the gastrocnemius and pectoralis major. Firing of the motor units can be followed almost to a maximum isometric contraction without the action potentials being lost in a mass of other motor unit potentials. A technique has also been developed whereby the position of a microelectrode in a human muscle during isometric contraction can be controlled by means of a micromanipulator. The possibility of inserting hard metal microelectrodes into human skeletal muscle percutaneously and positioning them with a micromanipulator substantially widens the range of the experimental work that can be carried on to elucidate the electrophysiological phenomena concerned in human skeletal muscle contraction. intramuscular tungsten microelectrode; isotonic and isometric contraction measurement Submitted on August 2, 1963
Relationship of pulmonary arterial and venous pressure to diffusing capacity
Authors: Lawson W. H. , Duke Helen N. , Hyde Richard W. , Forster Robert E. 
Published: December 2017

Single-breath carbon monoxide diffusing capacity (DlCO) was determined in ten isolated perfused cat lungs at 37 C during a) forward (arterial) perfusion through the pulmonary artery and b) reverse (venous) perfusion through the left atrium. Blood flow, inflow and outflow pressure, lung volume, and transpulmonary ventilating pressure were approximately equal in a and b, but in all ten lungs DlCO was greater in b than a. In five lungs during forward (arterial) perfusion blood flow was increased from a mean of 62–180 ml/min while left atrial outflow pressure was maintained about zero mm Hg. At the higher blood flow DlCO was not significantly changed although vascular resistance decreased a mean of 34% and arterial pressure increased a mean of 98%. We conclude that a) transmural pressure in the pulmonary veins is more important than that in the arteries in determining the size of the capillary bed as measured by DlCO, and b) the size of the capillary bed and total vascular resistance can vary independently. When pulmonary edema occurred in five lungs DlCO did not change significantly. pulmonary capillary bed size; pulmonary edema and lung diffusing capacity; pulmonary blood flow and lung diffusing capacity Submitted on February 11, 1963
Location and mechanism of airway constriction after barium sulfate microembolism
Authors: Nadel J. A. , Colebatch H. J. H. , Olsen C. R. 
Published: December 2017

Injection of barium sulfate microemboli into the right side of the heart of paralyzed, artificially ventilated cats increased pulmonary resistance, decreased pulmonary compliance and functional residual capacity, and increased end-expiratory transpulmonary pressure and anatomic dead space. These effects could be due to constriction of terminal respiratory units without significant narrowing of the large airways, which may actually enlarge. Anatomic studies, performed after rapid freezing of the lungs in the open thorax, showed that the principal site of constriction was the alveolar ducts. Intravenous isoproterenol partially or completely prevented the changes following microembolism, suggesting that they were due to smooth muscle contraction. Vagotomy, injection of heparin or atropine or guanethedine, or inhalation of 6% carbon dioxide did not prevent the changes; prior injections of 48/80 decreased the changes. These studies suggest that the embolism-induced changes depend on histamine release. The varied manifestations of barium sulfate microembolism, including the shift of ventilation to the unaffected areas, atelectasis of embolized areas, anoxemia, and abnormal breathing pattern may depend on the presence and extent of contraction of peripheral respiratory units induced by liberation of histamine. terminal airway constriction; histamine release; lung compliance; pulmonary resistance; airway anatomy; alveolar duct; muscle Submitted on August 30, 1963
Factors affecting regional distribution of ventilation and perfusion in the lung
Authors: Bryan A. C. , Bentivoglio L. G. , Beerel F. , MacLeish H. , Zidulka A. , Bates D. V. 
Published: December 2017

Regional distribution of ventilation and perfusion in the lung has been studied using Xe133 in normal subjects. In 31 subjects seated upright at rest the previous findings of a gradient of ventilation and perfusion distribution from apex to base of the lung, have been confirmed. The results agree well with those obtained using C15O2. In seven normal subjects lying supine, the V/Q distribution from apex to base of the lung is much more uniform, though a perfusion gradient can be shown to exist from front to back. Five normal subjects exercising on a bicycle ergometer in the upright posture were found to have a proportionately much greater blood flow through the upper zone of the lung than when in the same position at rest. One study during induced syncope on standing indicated that this state is accompanied by a progressive decrease in perfusion to the upper zones of the lung. No change in distribution occurred breathing 100% oxygen. xenon 133; posture; exercise; syncope; oxygen Submitted on August 30, 1963
Pulmonary gas exchange during induction of pulmonary edema in anesthetized dogs
Authors: Said Sami I. , Longacher Joseph W. , Davis Ronald K. , Banerjee Chandra M. , Davis William M. , Wooddell W. Jeff 
Published: December 2017

We examined pulmonary gas exchange in 19 anesthetized dogs during the induction of acute pulmonary edema by intravenous infusion of dextran in saline. We monitored pulmonary capillary pressure by a left atrial catheter, and arterial blood Po2 by an indwelling electrode. PaOO2 remained near normal until just before pulmonary edema was grossly apparent, when it fell precipitously; left atrial pressure mounted to a peak and then declined. The apparent “steady-state” DlCO was reduced as much as 61%, but the dominant cause of hypoxemia was an increased venous admixture (shunt flow) on O2 breathing. Since the shunt was reversible by forcible inflation of the lungs, induced pulmonary edema was probably associated with closure of alveolar units. pulmonary venous admixture (shunt flow) and diffusing capacity; alveolar closure; arterial blood oxygen; tension in vivo; hypoxemia Submitted on August 14, 1963
Cardiac output in muscular exercise at 5,800 m (19,000 ft)
Authors: Pugh L. G. C. E. 
Published: December 2017

Cardiac output during muscular exercise was estimated by the acetylene technique on four members of the Himalayan Scientific and Mountaineering expedition 1960–1961 at sea level and 5,800 m (19,000 ft). The output for a given work intensity at 5,800 m (19,000 ft) was comparable with the output at the same work intensity at sea level, but the maximum output was reduced, the mean value being 16 liters/min, compared with 23 liters/min at sea level. Heart rates during light and moderate exercise were higher than the rates observed at the same work intensity at sea level. The maximum heart rate during exercise was limited to 130–150 beats/min compared with 180–196 beats/min at sea level. The stroke volume at altitude was lower than at sea level at each work rate. On breathing oxygen at sea-level pressure, heart rate for a given work intensity was reduced; but the maximum heart rate increased. Indirect evidence suggested that maximum cardiac output increased but probably not to the sea-level values because of the increased hemoglobin and lower heart rate. altitude acclimatization; cardiac function, work and altitude; hypoxia and cardiac output Submitted on July 29, 1963
A bag-in-box system for maintaining gases at body temperature within the body plethysmograph
Authors: Sackner Marvin A. , Feisal Khalil A. , DuBois Arthur B. 
Published: December 2017

Measurements of the tissue volume and CO2 dissociation slope of the lungs by a plethysmographic technique require maintenance of the inspired gases at body temperature and saturation with water. For such a purpose, the design of a thermostatically controlled bag-in-box system which introduces negligible dead space between the mouth and bags is described. apparatus for measurement of pulmonary tissue volume; bag-in-box system with negligible dead space; thermostatically controlled bag-in-box system Submitted on August 26, 1963
An improved suction electrode for recording from the dog heart in situ
Authors: Churney Leon , Ohshima Hisashi 
Published: December 2017

Action potential recordings by suction electrodes are generally small, unstable, and replete with artifacts like afterpotentials and incorrect values of the action potential overshoot. These electrodes record from the surface of the tissue plug imbedded in the electrode opening. This plug was found to have high electrical impedance, which accounts for the undesirable features of the recordings. The improved electrode yields negative-going resting potentials, and action potentials of 70–80 mv, routinely and for periods of 3–4 hr. The value of the overshoot compares with that recorded by glass microelectrodes. Afterpotentials are absent. The improvement results from the fact that the recording wire bypasses the tissue plug and is presumably recording from live, if injured, cells. We corroborate the important finding (B. F. Hoffman et al. Am. J. Physiol. 196: 1297, 1959) that the falling limbs of action potentials recorded simultaneously by suction and microelectrodes are coincident. cardiac electrophysiology; suction electrodes and microelectrodes Submitted on December 12, 1963
Plasma and red cell volume after prolonged severe exercise
Authors: Åstrand Per-Olof , Saltin Bengt 
Published: December 2017

On six subjects plasma volume (Evans blue space) was determined before and 1 hr after an 85-km race in cross-country skiing. The total water loss during the 5- to 9.5-hr competition was estimated to be 5.9 liters, and at the time of measuring the reduction in body weight was 3.9 kg or 5.5% of the weight. The plasma volume was increased 0.41 or 11% (0.01 > P > 0.001). A similar study was undertaken with measurements of red cell volume (Cr51) on five subjects. The decrease in red cell volume was 0.081 or 3.2%. These findings are discussed in light of the small reduction in aerobic work capacity in combination with a marked decrease in total work output after the race. In five workers in a steel mill (three at a hot bank and two at a smelting furnace) the total water loss during an 8-hr shift in a hot environment was 3.9 liters and the reduction in body weight was 1.1 kg or 1.9% of the weight. The blood volume (I131) was increased by 0.23 liters or 3.5%. dehydration; blood volume Submitted on October 16, 1963
Effects of mass loading the respiratory system in man
Authors: Sharp J. T. , Henry J. P. , Sweany S. K. , Meadows W. R. , Pietras R. J. 
Published: December 2017

Mass loading of the thorax in four normal conscious subjects and in six anesthetized paralyzed subjects transposed the thoracic volume-pressure curve to higher levels on the pressure axis without greatly affecting the slope of its linear portion. This effect is similar to that produced by forward acceleration and snorkel breathing. Mass loading the lower thorax produced a greater effect than mass loading the upper thorax. Mass loading the abdomen flattened the slope of the linear portion of the thoracic-volume pressure curve both in conscious subjects and in anesthetized paralyzed subjects, the effect resembling that of elastic loading which also flattened the thoracic volume-pressure curve. The shape of the total respiratory static volume-pressure curves in six of ten excessively obese subjects resembled that produced by thoracic mass loading in normal subjects. Five patients with the obesity-hypoventilation syndrome had curves suggesting a combination of elastic and mass loading or alternatively, abdominal mass loading. At any lung volume, the total transrespiratory static pressure is made up of a volume-dependent elastic component and a volume-independent gravitational component. The latter is approximately 5 cm H2O in the supine adult male of normal weight. thoracic compliance; total respiratory compliance; gravitational effects on thorax; respiratory compliances in obesity Submitted on January 6, 1964
Diffusing capacity of the lung in pulmonary emphysema
Authors: Ayres Stephen M. , Buehler Meta E. , Armstrong Ruth G. 
Published: December 2017

Steady-state CO and O2 methods for measuring pulmonary diffusing capacity may be affected by abnormal distribution of inspired gas relative to perfusion. These methods frequently fail to separate abnormalities in diffusion from abnormalities in distribution in patients with obstructive emphysema. A rebreathing CO method has been developed which, in theory, is less sensitive to inequalities in distribution. The DlCO by this method in 41 normal subjects averaged 20.8 ± 8.6 ml/min mm Hg and was closely correlated with body size and lung volume. Only 3 of 25 patients with obstructive emphysema had a DlCO less than the 95% confidence level although the mean value for all of the patients (16.8 ml/min mm Hg) was significantly lower than that of the normal group. It is concluded that loss of diffusing surface is not a common cause of oxyhemoglobin desaturation in obstructive emphysema. diffusion; carbon monoxide; ventilation-to-perfusion; gas chromatography Submitted on December 27, 1963
Use of a cross-circulation technique in studying respiratory responses to CO2
Authors: Michel C. C. , Kao F. F. 
Published: December 2017

The effect of hypercapnia and hypocapnia on ventilation was investigated in cross-circulated dogs in which the recipient dog's head and neck regions were perfused by blood from a donor dog. Hypercapnia of the donor dog was produced by administering CO2-O2-N2 gas mixtures in the inspired air. Hypocapnia was produced by hyperventilating the donor dog with the aid of a respiratory pump. When the donor dog was hyperventilated, the ventilation of the recipient was maintained at or just below its resting level and it was independent of the arterial Pco2 of the donor. The donor dog was apneic when the artificial hyperventilation was suspended and this response was not abolished by vagotomy. Bilateral vagotomy caused an increase in ventilation in the recipient when its head was perfused by hypocapnic blood. Bilateral removal of the carotid receptors did not influence the response to CO2 qualitatively although there was some reduction in the ventilation of the recipient to cephalic hypercapnia. The ventilation of the recipient dog was best correlated to the pH and Pco2 of its cerebrospinal fluid in both hypercapnic and hypocapnic states. Note: (With the Technical Assistance of S. S. Mei) respiration; cerebrospinal fluid; apnea; central chemosensitivity; perfusion techniques; hypocapnia; hypercapnia; regulation of ventilation; chemoreceptors; hyperventilation Submitted on February 19, 1964
Effect of sweat loss on body fluids
Authors: Kozlowski Stanislaw , Saltin Bengt 
Published: December 2017

Six healthy men were studied under normal conditions and after dehydration caused by sweating produced 1) in a sauna at 80 C, 2) by hard muscular work at 18 C, and 3) by mild exercise at room temperature 38 C. The dehydration period lasted for 2.5@#X2013;3.5 hr. Sweat was collected in impermeable plastic bags around the forearm. Body weight, Evans blue space, and apparent inulin space were determined before and about 90 min after the dehydration period. The average decrease in body weight was 3.1 (4.1%), 3.1, and 3.5 kg for 1, 2, and 3, respectively. The reduction in apparent inulin space was 1.4, 0.2 and 1.3 liters, respectively. The decrease in Evans blue space paralleled the reduction in apparent inulin space. In the three conditions no significant differences were found in calculated total loss of electrolytes. Water liberated from combustion of fat and carbohydrates plus water previously stored with glycogen can account for up to 1.1 liters of the intracellular water loss during the hard exercise (2). The additional water loss from the cells is discussed in light of electrolyte shifts. dehydration; intracellular fluid; extracellular fluid; plasma volume Submitted on January 20, 1964
Elevation of mean circulatory pressure in dogs with cerebral ischemia-induced hypertension
Authors: Richardson Travis Q. , Fermoso Jóse D. 
Published: December 2017

The Cushing reflex was elicited in 12 dogs. After the mean arterial pressures had become elevated, the mean circulatory pressures were measured. Mean circulatory pressure increased from the control of 7 mm Hg up to approximately 2.5 times the control when the mean arterial pressure was elevated to approximately 240 m Cushing reflex; intracranial compression Submitted on March 16, 1964
Factors influencing the concentration of expired nitrogen after a breath of oxygen
Authors: Mills R. J. , Harris P. 
Published: December 2017

In normal subjects, the change in the concentration of nitrogen in expired alveolar air after a single breath of oxygen has been found to be affected by the presence of a pause at the end of inspiration, by varying rates of expiration, and by variations in the initial volume of air in the lungs. The effects of these different respiratory maneuvers are analyzed in terms of the over-all dilution of the inspired oxygen, of the unequal and asynchronous movements of the chest wall, and of the presence of a distribution of ventilatory time constants. The evidence suggests that there is a greater uniformity of ventilatory time constants at a middle lung volume than at a high or low lung volume. distribution of ventilation Submitted on January 27, 1964