bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic particle size measurements of platelet aggregates formed in vitro
Authors: Solis R. T. , Wright C. B. , Gibbs M. B.
Published: December 2017

The aggregation of human platelets induced by adenosine diphosphate (ADP) was used to evaluate electronic particle size analyzer measurements of platelet aggregates in plasma. As platelets began to clump in plasma, the total volume and the diameter of individual aggregates increased; after a time dependent on experimental conditions, the diameter increased but the total volume remained unchanged. Similar but opposite changes in size distribution occurred during platelet deaggregation. The total volume of aggregates formed in plasma varied (linear correlation coefficient = 0.99) with the total volume of platelets which were available to clump and with simultaneous changes in optical density. The diameter of the aggregates varied with the concentration of, and time of exposure to, ADP and with the total volume of platelets and aggregates in plasma was not different from that of control platelets in untreated plasma, the individual platelets aggregated without an accompanying increase in size. This study demonstrates that platelet aggregation can be characterized by electronic measurements of the size distribution of platelet aggregates.
Effect of vibration on isolated dog bronchi
Authors: Sinclair A. S. , Roach M. R.
Published: December 2017

Vibratory stress, induced by turbulent flow, has been shown to alter the structural properties in arteries. Since turbulent flow can exist in the lungs it seems important to know whether a similar effect can occur in bronchi. To answer that question air was passed through isolated dog bronchi. Turbulent flow was created by having, at one end, a cannula acting as a stenosis, producing vibrations or a “flitter” in the wall. A measure of the elastic properties was obtained by coupling pressure-volume data with photographs taken at different pressures. The results demonstrate a significant alteration in the structural properties, localized to ares under maximum vibration. A “yielding” in the direction of maximum stress was observed with a corresponding structural rearrangement (radius decreased, length increased). This effect and its relation to structural fatigue is discussed. The physiological significance of the results are that the bronchi become more resistant to deformation under positive pressures and less resistant to collapse under negative pressures.
Cardiac performance during graded exercise in acute hypoxia
Authors: Manchanda Subhash C. , Maher John T. , Cymerman Allen
Published: December 2017

To evaluate the cardiocirculatory changes induced by acute hypoxic stress, rate corrected electro-mechanical systole (QS2)) left ventricular ejection time (LVET), and preejection period (PEP) were determined in 11 healthy males at sea level (SL) and after 2 h at a simulated altitude (HA) of 4,300 m. Recordings were made at rest and at 15 min of upright bicycle exercise at light and moderately heavy loads (40 and 75% of Vo2 max, respectively). Venous blood was withdrawn simultaneously for estimation of total plasma catecholamines (CATS). Exposure to HA produced a significant decrease in each interval at rest with differences narrowing progressively with exercise of increasing intensity. PEP/LVET ratio decreased progressively with graded exercise at SL indicating an enhancement of left ventricular performance that was directly related to the elevation in plasma CATS. Cardiac performance was augmented at rest during HA exposure, despite a normal level of CATS. However, during moderately heavy exercise at HA, when the plasma CATS were increased to twice the SL values, cardiac performance, as reflected by the PEP/LVET ratio, did not increase proportionately. It is postulated that the depressant effect of increased hypoxemia and acidosis during moderately heavy exercise in HA may override the cardiostimulatory influence of circulating CATS.
Decreased oxygen uptake with stored blood in the isolated hindlimb
Authors: Yhap E. O. , Wright C. B. , Popovic N. A. , Alix E. C.
Published: December 2017

Storage of red cells in acid-citrate-dextrose (ACD) solution for more than a week has been shown to cause a reduction in red cell 2,3-diphosphoglycerate (2,3-DPG), resulting in a decrease in the half-saturation pressure (P50) of stored blood, thus increasing hemoglobin-oxygen affinity and theoretically decreasing oxygen delivery to the tissues. A method to isolate and perfuse the hindlimb in a dog has been developed and used successfully to compare the difference of oxygen release between banked and fresh ACD blood. Ten dogs were perfused using canine blood collected in standard blood transfusion bags containing ACD and stored at 4 degrees C and fresh blood collected in a similar manner but used immediately. The total oxygen release in the limb during perfusion with fresh blood was significantly greater than during perfusion with stored blood.
Effect of end-expiratory airway pressure on accumulation of extravascular lung water
Authors: Demling R. H. , Staub N. C. , Edmunds L. H.
Published: December 2017

The effect of end-expiratory airway pressure on the accumulation of extravascular lung water during lobar venous occlusion for 2 h was studied in closed-chest artifically ventilated dogs. Dogs were divided into two groups by end-expiratory airway pressures of 0 or 10 cmH2O. High-pressure lobar pulmonary edema was produced by lobar venous occlusion, which elevated microvascular hydrostatic pressure. After occlusion of the lobar pulmonary vein, lobar venous pressure (and microvascular hydrostatic pressure) rapidly became identical to pulmonary arterial pressure. We measured extravascular lung water (post mortem) and pulmonary arterial pressure and calculated plasma colloid osmotic pressure to determine the relationship between the accumulation of lung water and the difference between pulmonary microvascular pressure and plasma colloid osmotic pressure (net intravascular filtration pressure). At comparable net intravascular filtration pressures, dogs ventilated at the higher end-expiratory airway pressure accumulated more extravascular lung water. This study indicates that increasing end-expiratory airway pressure from zero to 10 cmH2O increases the accumulation of extravascular lung water when microvascular hydrostatic pressure is raised.
Effects of topical and general anesthetic agents on tracheal mucous velocity of sheep
Authors: Landa J. F. , Hirsch J. A. , Lebeaux M. I.
Published: December 2017

Tracheal mucous velocity was estimated in eleven sheep by means of cine-bronchofiberscopic technique in which Teflon discs placed on the tracheal mucosa were filmed as markers. The procedure was done using a transnasal approach in conscious nonanesthetized sheep, and in the same sheep using topical and/or general anesthetic agents. The average mucous velocity in conscious sheep was 17.3 plus or minus 6.2 (SD) mm/min; in sheep anesthetized with intravenous pentobarbital or thioamylal, the average velocity was significantly depressed to 11.1 plus or minus 3.6 mm/min. No Significant differences in tracheal mucous velocity were found when 10 ml of 2 percent lidocaine was instilled into the tracheas of either conscious sheep or sheep under general anesthesia. Sheep as an animal model appear to be ideal in the study of the responses of tracheal mucous velocity to physical and chemical agents since they tolerate bronchofiberscopy quite well without the use of topical or general anesthetic agents. The basis for the depression of tracheal mucous velocity by barbiturates cannot be ascertained from the present study but the model should be useful for comparing different types of anesthetic agents.
Inhibition of respiratory reflexes by local anesthetic aerosols in dogs and rabbits
Authors: Dain D. S. , Boushey H. A. , Gold W. M.
Published: December 2017

The effects of inhalation of 100 breaths of bupivacaine hydrochloride (5 percent solution in saline) on the cough reflex, the Breuer-Hering inflation, reflex, and the duration of apnea and bronchoconstriction produced by histamine aerosol were studied in nine anesthetized dogs. Cough was abolished in every animal; the duration of the inflation reflex was shortened from 47 +/- 4.6 s (mean plus or minus SE) to 16 +/- 3.4 s. The duration apnea produced by histamine was abolished or shortened and the rise in resistance was diminished from 170 plus or minus 22 per cent (control) to 49 +/- 6 per cent (after bupivacaine). These reflexes returned toward control values within 45 min. Bupivacaine inhibited the bronchoconstriction produced by electrical stimulation of the distal ends of cut vagus nerves both in dogs and in rabbits, but it did not alter the rise in resistance produced by histamine aerosol in vagotomized dogs. We conclude that administration of bupivacaine aerosol produces a reversible blockage of both afferent and efferent nervous activity in airways without abolishing the ability of smooth muscles to contract.
Measurement of gastric blood flow with radioactive microspheres
Authors: Archiabld L. H. , Moody F. G. , Simons M.
Published: December 2017

The validity of using radioactive microspheres (15 +/- 5-mum diameter) to measure gastric blood flow and its partition between gastric wall layers was investigated in anesthetized dogs with a chambered segment of gastric corpus. Total flow measured by a venous effluent technique demonstrated close correlation with microsphere-measured flow (r = 0.98, slope = 0.95) in 12 dogs given histamine, gastrin, or isoproterenol. In 12 histamine-stimulated dogs, mucosal flow measured by aminopyrine clearance and by microspheres also showed good agreement (r = 0.96, slope = 0.83). No evidence was found to indicate that microspheres altered hemodynamic or gastric function. In all experiments less than 1% of the total gastric radioactivity passed through arteriovenous shunts. The mucosa always contained a statistically adequate number of spheres (greater than 400), but the submucosa and muscularis frequently did not. Microspheres of all sizes mixed adequately in large arteries, but a significant difference was found in the distribution of 16- and 26 mum spheres between mucosa and submucosa, presumably because of streaming of the larger spheres past mucosal arteries. It was concluded that, with the techniques developed in our laboratory, microspheres could be a highly useful tool for quantitating gastric regional blood flow under a variety of experimental conditions.
Effect of behavioral variables on cooling rate of man in cold water
Authors: Hayward J. S. , Eckerson J. D. , Collis M. L.
Published: December 2017

Five different behaviors of man while in cold ocean water (9–10 degrees C) were assessed for their effect on rate of progress into hypothermia. With subjects wearing lifejackets, two thermally protective behaviors were studied which reduce exposure to the water of areas of body surface with high relative heat loss potential. One was huddling of three persons and the other a self-huddle behavior (HELP or Heat Escape Lessening Posture). These two behaviors resulted in significant reductions of rectal temperature cooling rate of 66 per cent and 69 per cent, respectively, of that of a control behavior. With no flotation available, two survival swimming behaviors (treading water and drownproofing) were shown to result in significant increases in cooling rate to 134 per cent and 182 per cent, respectively, of the control behavior. Potential swimming distance of subjects wearing a life-jacket was 0.85 miles in water near 12 degrees C before predicted incapacitation by hypothermia. It was concluded that behavioral variables can be of major importance in determining survival time in cold water through modulation of cooling rate associated with other variables such as fatness, body size, and clothing.
Thermoregulatory control of finger blood flow
Authors: Wenger C. B. , Roberts M. F. , Nadel E. R. , Stolwijk J. A.
Published: December 2017

Three men exercised on a bicycle ergometer at 30, 50, asd 70 per cent of maximal aerobic power in ambient temperatures of 15, 25, and 35 degrees C with water vapor pressure less than 18 Torr. Exercies was used to vary internal temperature during as experiment, and different ambient temperatures were used to vary skin temperatures independently of internal temperature. Finger temperature was fixed at about 35.7 degrees C. Espohageal temperature (Tes) was measured with a thermocouple at the level of the left atrium, and mean skin temperature (Tsk) was calcualted from a weighted mean of thermocouple temperatures at eight skin sites. Finger blood flow (BF) was measured by electrocapacitance plethysmography. Although some subjects showed small and equivocal vasomotor effects of exercise, our data are well accounted for by an equation of the form BF equal to alTes + a2Tsk + b, independent of exercise intensity. For these subjects, the ratios a1/a2 (5.9, 8.6, 9.4) were similar to the ratios of the corresponding coefficients recently reported for thermaoregulatory sweating (8.6, 10.4) and for forearm blood flow (9.6).
2-Deoxy-D-glucose inhibition of prostaglandin E1 hyperthermia and yeast fever in mice
Authors: Robinson S. M. , Mager M.
Published: December 2017

2-Deoxy-D-glucose (2-DG) and sodium salicylate were evaluated relative to their effects on body temperature in mice with prostaglandin E1 (PGE1)hyperthermia or yeast fever. Injection of 2-DG into the cerebral ventricles of conscious mice abolished the hyperthermia of PGE1 and reduced the fever produced by yeast, while sodium salicylate was effective only in yeast fever. The data are suggestive of glucose dependency of thermoregulatory centers in the brain.
Lung volumes, mechanics, and single-breath diffusing capacity in anesthetized cats
Authors: Watanabe S. , Frank R.
Published: December 2017

We measured lung weight, lung volumes, pulmonary mechanics, and carbon monoxide transfer (DLCO, single-breath method) in healthy cats (3.3 +/- 0.4 kg) that were anesthetized, paralyzed, and mechanically ventilated through a tracheal cannula. Compared with Stahl's predicted values which were based on regression analyses of data collected from several species, our cats had larger and more compliant lungs in relation to body weight, higher DLCO per unit body weight, and similar DLCO/TLC (size independent constant). Compared with Robinson et al.'s values derived entirely from studies on dogs, our cats had significantly smaller lung volumes and DLCO per unit body weight, DLCO/TLC and similar ratios of CL/FRC. Several factors appear to contribute to the functional variations among mammalian species: differences in the relation of lung to body weight, differences in the relation of chest wall compliance to lung compliance, and differences in the fundamental structure and design of the respiratory systems. Differences in methodology are acknowledged to be an additional factor.
Branching pattern of airways and air spaces of a single human terminal bronchiole
Authors: Hansen J. E. , Ampaya E. P. , Bryant G. H. , Navin J. J.
Published: December 2017

A polyurethane-foam enlarged reconstruction was made from serial sections of a portion of young adult human lung parenchyman. Study of the progeny of a terminal bronchiole disclosed three generations of respiratory bronchioles and an irregular branching pattern of eight generations of alveolar ducts. Sacs and alveoli arose from the lateral and distal aspects of all generations of ducts. There were an average of 3.5 alveoli per sac. Considering the terminal bronchiole as the first generation branch of the acinus, over 60 per cent of the alveoli counted and predicted were members of the 10–12th generations. The acinus contained one terminal bronchiole and approximately 14 respiratory bronchioles, 1,200–1,500 ducts, 2,500–4,500 sacs, and 14,000–20,000 alveoli.
Avian ventilatory responses to dynamic CO2 signals
Authors: Miller D. A. , Kunz A. L.
Published: December 2017

This study uses an awake unidirectionally ventilated avian preparation to examine the effects of dynamic CO2 signals on the respiratory drive. Results show that minute ventilation is affected by both 1) mean CO2 level and 2) amplitude of CO2 oscillations at the frequency of breathing. An increase in mean CO2 level increased minute ventilation. Comparisons of the effects of CO2 oscillations at the same mean CO2 level, however, showed minute ventilation to be less with the larger amplitudes of oscillations than with smaller ones. Graphs of minute ventilation (V) versus mean CO2 for families of oscillation sizes (0.5%, 1% and 2%) showed that the ventilatory sensitivity (slop) was least for the 2% oscillations and greatest for the 0.5% oscillations. Therefore, a static model for the respiratory regulator is not adequate. However, the apneic level of CO2 (V = O intercept) was independent of the size of the CO2 oscillations.
Heat transport in laminar flow of erythrocyte suspensions
Authors: Ahuja A. S.
Published: December 2017

Measurements of thermal conductivity were made in laminar flow of dog and turkey erythrocyte suspensions in a stainless stell tube of about 1 mm ID. These measurements were independent of the shear rate, showing that the red cell motion relative to plasma in flowing blood had no effect on the heat transfer. Measurements of thermal conductivity were further made in suspensions of polystyrene spheres of 100 mum and were found to be dependent upon the shear rate. The Graetz solution corresponding to uniform wall temperature was used for determining the value of thermal conductivity in an apparatus calibrated with tap water. The overall accuracy of the results is within 10%. A model based on the particle rotation with the entrained fluid is proposed. It is pointed out that the diffusion of platelets, red cells, and possibly plasma proteins (such as fibrinogen) will be augmented if they happen to be in the hydrodynamic field of rotating erythrocytes.
Nonperipheral chemoreceptor stimulation of ventilation by cyanide
Authors: Levine S.
Published: December 2017

To assess the ventilatory responses elicited by changes of tissue hypoxia, sodium cyanide (0.12 mg/kg-min for 10 min) was infused into the upper abdominal aorta of anesthetized dogs. These infusions produced decreases in oxygen consumption, increases in arterial lactate concentration, and increases in arterial lactate/pyruvate ratio. Coincident with these metabolic changes of hypoxia, minute ventilation (VE) increased 228 +/- SE 36% and arterial PCO2 decreased 21 +/- SE 2 mmHg; therefore, pH increased both in arterial blood in and cisternal cerebrospinal fluid. Following infusion of cyanide into the abdominal aorta, small quantities of cyanide (48 +/- SE 14 mumol/liter) appeared in carotid arterial blood. To evaluate the possibility that the observed increases in VE were due to stimulation of peripheral arterial chemoreceptors by the recirculating cyanide, the carotid and aortic chemoreceptors were denervated in four dogs. Nonetheless, after intra-aortic infusion of sodium cyanide (1.2 mg/kg), ventilation in these chemodenervated animals again increased considerably (154 +/- SE 36%). In order to explore the possibility that cyanide infusion can stimulate ventilation by an extracranial mechanism, heads of vagotomized dogs (including the carotid bodies) were perfused entirely by donor dogs. The intra-aortic infusion of sodium cyanide (0.9 mg/kg) into these head-perfused animals still caused large increases in VE (163 +/- SE 19%). It is concluded that intra-aortic cyanide infusions stimulate VE by an extracranial mechanism other than the carotid and aortic chemoreceptors.
A multichannel implantable telemetry system for flow, pressure, and ECG measurements
Authors: Fryer T. B. , Sandler H. , Freund S. W. , McCutcheon E. P. , Carlson E. L.
Published: December 2017

The design of telemetry systems for chronic implantation within the body have progressed from simple single-channel devices to complex multichannel systems over the last 15 yr. Although chronic measurements of temperature, ECG, and pressure have been reported with good results, measurements such as dimension and blood flow have been difficult because of heavy power requirements. The design to be described is a multiplex system that will measure up to eight individual parameters simultaneously, including blood flow. Flow is measured using an electromagnetic transducer, and by special design, the normal high power requirements of the electromagnetic technique have been reduced to a few hundred milliwatts. The system is powered by two NiCad, rechargeable batteries which are periodically recharged through the intact skin by induction at 250 kHz to an implanted pickup coil. The presently constructed units have been configured to measure ECG, two pressures, temperature and ascending aortic flow.
Renal blood flow distribution during steady-state exercise and exhaustion in conscious dogs
Authors: Delgado R. , Sanders T. M. , Bloor C. M.
Published: December 2017

To determine whether renal blood flow is reduced or redistributed during exercise, we measured total renal flow (TRF) and intrarenal flow distribution (IRFD) in nine dogs. They ran on a motor-driven treadmill at 3–8 mph at grades of 8–15% for an average of 35 min. We measured aortic pressure, heart rate, stroke volume, and cardiac output (CO) via chronically implanted catheters and an electromagnetic flow probe. We injected 15-mum radiolabeled microspheres (85Sr, 141Ce, and 51Cr) via a left atrial catheter during resting control, steady state (SS) and exhaustive (EE) exercise; measured their distribution by gamma spectrometry; and determined TRF as % CO and as ml/100 g per min. We determined IRFD for the outer and inner cortex and the outer medulla. TRF as %CO dropped (P less than 0.05) during both levels of exercise: from 10.2 +/- 0.7% to 3.9 +/- 0.4% (SS) and 3.4 +/- 0.6% (EE). TRF in ml/100 g per min did not change significantly from control (228 +/- 30 ml/100 g per min). IRFD was unchanged with exercise, remaining at about 80, 20, and 3% of TRF for the outer and inner cortex and outer medulla, respectively. We conclude that blood flow is not diverted from the kidneys during severe exercise in the dog.
High-resolution radioisotopic measurements of calcium, strontium, and barium in heart
Authors: Sanborn W. G.
Published: December 2017

A gamma-ray detector system used in conjunction with isolated vascularly perfused rabbit septa labeled with the Ca-like cations 85Sr and 133Ba has been developed to test the feasibility of constructing a considerably more efficient detector system capable of measuring the highly energetic (Emax congruent to 1.3 MeV) 47Ca radionuclide. In addition an experimental design has been developed to quantify, statistically, perturbations of total tissue Ca, Sr, or Ba should they occur. This project was undertaken because the severe attenuation by living tissue of the beta-emitting radionuclide 45Ca (Emax congruent to 250 keV) limits its usefulness as a Ca tracer during experiments in which total tissue Ca is being measured minute-by-minute by an external detector. Analyses of over 100 experiments conducted on 35Sr- and 133Ba-labeled rabbit septa indicate that a tissue-detector system can be developed having the capacity to resolve perturbations of as little as 2 mumol Ca/kg wet tissue at 1-min sampling times or 6 mumol Ca/kg wet tissue at 0.1-min sampling times.
Electrical activity of phrenic nerve and diaphragm in utero
Authors: Bahoric A. , Chernick V.
Published: December 2017

Phrenic nerve activity, diaphragmatic EMG, and tracheal or pleural pressure changes were recorded in a chronic fetal sheep preparation. Three patterns of fetal phrenic nerve activity were observed: 1) a single burst; 2) irregular nonrhythmic bursts; and 3) prolonged rhythmic activity, seen only prior to fetal death. The total recording time was 54.53 h and the total duration of phrenic nerve activity was 65.34 min (2.16%). When an inactive period was defined as the absence of phrenic nerve activity for 60 s or more, active periods occupied 44.7% of the total time. Phrenic nerve activity was present in all fetuses and 97.5% of the time was coupled with diaphragmatic EMG. Both diaphragmatic EMG and intrapulmonary pressure changes occurred in the absence of phrenic nerve activity. In three fetal animals both phrenic nerves were transected. Tracheal pressure changes were seen which were not coupled with corresponding intrauterine pressure changes. Thus, changes in fetal tracheal pressure or diaphragmatic EMG do not necessarily represent the output of the fetal respiratory center. This study suggests that the fetal respiratory center is active in utero, but this activity is minimal and has a different pattern that that present after birth.
Effective respiratory system elastance during positive-pressure breathing in supine man
Authors: Josenhans W. T. , Peacocke T. A. , Schaller G.
Published: December 2017

Two healthy males relaxing supine on a ballistobed were mechanically ventilated at positive end-expiratory pressures (PEEP) from 0 to 19 cmH2O. Pressures at the airway opening, middle esophagus, and stomach were monitored, together with tidal volume (VT) and ballistobed displacement. The effective elastance (i.e., sum of active and passive components) of the respiratory system (E'rs) and its components--abdominal muscle (E'ab), diaphragm (E'di), and rib cage (E'rc)--were calculated. With increasing PEEP, lung compliance increased slightly, E'rc and E'di decreased linearly, and E'ab increased linearly. The combined effective elastance of abdomen and diaphragm (E'ab+di) first decreased and then increased again. The abdomen-diaphragm contribution to VT during mechanical ventilation was approximately half that of spontaneous breathing.
Effect of elastic loading on ventilatory response to hypoxia in conscious man
Authors: Rebuck A. S. , Betts M. , Saunders N. A.
Published: December 2017

Ventilatory responses to isocapnic hypoxia, with and without an inspiratory elastic load (12.1 cmH2O/l), were measured in seven healthy subjects using a rebreathing technique. During each experiment, the end-tidal PCO2 was held constant using a variable-speed pump to draw gas from the rebreathing bag through a CO2 absorbing bypass. Studies with and without the load were performed in a formally randomized order for each subject. Linear regressions for rise in ventilation against fall in SaO2 were calculated. The range of unloaded responses was 0.74–1.38 1/min per 1% fall in SaO2 and loaded responses 0.71–1.56 1/min per 1% fall in SaO2. Elastic loading did not significantly alter the ventilatory response to progressive hypoxia (P greater than 0.2). In all subjects there was, however, a change in breathing pattern during loading, whereby increments in ventilation were attained by smaller tidal volumes and higher frequencies than in the control experiments. These results support the hypothesis previously proposed in our studies of resistive loading during progressive hypoxia, that a similar control pathway appears to be involved in response to the application of loads to breathing, whether ventilation is stimulated by hypoxia or hypercapnia.
Slow respiratory stimulant effect of hyperoxia in chemodenervated decerebrate cats
Authors: Rosenstein R. , McCarthy L. E. , Borison H. L.
Published: December 2017

A direct stimulating action of oxygen on the CO2 respiratory control system was determined from steady-state and dynamic observations in unanesthetized decerebrate cats. In peripheral nerve-intact animals, inhalation of oxygen (1 atm) produced a small but significant shift to the left as well as a decrease in slope in the steady-state VT vs. log PACO2 relationship. Carotid sinus neurotomy more than doubled the shift, to the extent that the mean PACO2 apneic point was lowered by 6.5 mmHg. Neither vagotomy nor chronic ablation of the area postrema had any detectable influence on the stimulating effect of oxygen on CO2 responsiveness. The arterial-alveolar PCO2 difference, prior to and following carotid chemo-denervation, remained unchanged or was increased by a negligible amount during oxygen inhalation. The oxygen threshold for respiratory stimulation, obtained isocapnically, occurred between 115 and 200 mmHg; VT then increased exponentially tending to level off as PAO2 approached 1 atm. The dynamic response to sudden presentation of oxygen after carotid chemodenervation consisted of a monotonic rise in VT, starting after 20–30 s with a t 1/2 of about 75 s.
Oxygen-induced changes in pulmonary phospholipids in the rat
Authors: Valimaki M. , Pelliniemi T. T. , Niinikoski J.
Published: December 2017

The composition and synthesis of alveolar and lung tissue phospholipids were investigated in normal and oxygen-poisoned rat lungs. Sixty-hour exposure to oxygen increased the total amount of phospholipids in the endobronchial extracts and lung tissue. Phosphatidyl glycerol was identified in both endobronchial extracts and lung tissue. The amount of unsaturated fatty acids in surfactant lecithin and phosphatidyl glycerol was slightly increased in oxygen-poisoned lungs whereas the composition of phospholipids in the endobronchial extracts was not affected by oxygen. After intraperitoneal administration of [32P]phosphate the specific activities of surfactant lecithin and phosphatidyl glycerol were clearly lower in oxygen-treated animals whereas the specific activities of lung tissue lecithin and phosphatidyl glycerol remained unaffected. The synthesis of lecithin from [14C]methionine through N-methyltransferase pathway was markedly depressed in lung slices but increased in liver tissue taken from oxygen-poisoned rats and incubated under oxygen indicating a difference between lung and liver methyltransferase enzymes. In conclusion, the present work suggests impaired synthesis and removal of alveolar phospholipids in oxygen-poisoned rats.
Respiratory sinus arrhythmia: noninvasive measure of parasympathetic cardiac control
Authors: Katona P. G. , Jih F.
Published: December 2017

The degree of parasympathetic heart rate control, PC, was defined as the decrease in average heart period (RR interval) caused by the elimination of parasympathetically mediated influences on the heart while keeping sympathetic activity unchanged. By reviewing published results on the interaction of sympathetic and parasympathetic heart rate control, the prediction was made that PC should be directly proportional to VHP, the peak-to-peak variations in heart period caused by spontaneous respiration. In sevel chloralose/urethan-anesthetized dogs the vagi were reversibly blocked by cooling, and PC (the difference between average heart period before and after cooling) and VHP (without cooling) were determined under a variety of conditions that included a) increasing vagal activity by elevating the blood pressure b) sympathetic blockade, and c) parasympathetic blockade. The relationship between VHP and PC was linear with an average correlation coefficient of 0.969 +/- 0.024 (SD) and a PC-axis intercept of 15.2 +/- 25.9 ms. In each dog the correlation coefficient between VHP and PC was higher than between VHP and the average heart period (avg correlation coef: 0.914 +/- 0.044). These results suggest that the degree of respiratory sinus arrhythmia may be used as a noninvasive indicator of the degree of parasympathetic cardiac control.
Menstrual variations in thermal properties of the human breast
Authors: Nassar A. M. , Smith R. E.
Published: December 2017

Menstrual variations in breast skin temperature (Tbr), heat flow (HF), volume (Vol), surface area (A), and core temperature (Tre) have been measured in 13 women. Measurements were made twice weekly on resting subjects throughout one cycle. Twelve of thirteen subjects showed increased Vol and A during the second half of the menstrual cycle; six also showed a minor peak prior to the midcycle rise in Tre. Eight of thirteen subjects had significant peaks in Tbr which preceded the estimated day of ovulation. Breast HF was generally low during the first half of the cycle, rising following estimated ovulation. Analysis of core-to-breast conductance indicates that a decrease in resistance to heat transfer occurs both during the luteal phase and at the Tbr peak. It is hypothesized that the control mechanism underlying the Tbr peak is independent of that controlling the postovulatory increases in Vol, HF, and Tre.
Longitudinal measurements of blood volume and essential body mass in human subjects
Authors: Chien S. , Peng M. T. , Chen K. P. , Huang T. F. , Chang C. , Fang H. S.
Published: December 2017

Repeated determinations of blood volume and body density were made on 34 Chinese subjects (28 men and 6 women) in Taiwan over a period of 12 yr, as the mean age increased from 31 to 43 yr. Essential body mass calculated from body density and body weight showed no significant change over the 12-yr period. Changes in body weight (mean gain equals 6.0 kg) were attributable to alterations in adipose tissue weight, the density of which was found to be 0.948 g/cm3. In two-thirds of the subjects the second blood volume increased by more than 5% over the first determination, and the mean blood volume for all subjects increased by 7.5% (P less than 0.01). Correlation of the blood volume data with the findings on essential body mass and adipose tissue mass suggests that blood content per unit tissue mass increased in the second determination. This interpretation is supported by the increase in nutrient availability in Taiwan over the 12-yr period, and it may explain the lack of blood volume increase in an earlier longitudinal study on American subjects with stable nutrient availability.
Longitudinal studies on adipose tissue and its distribution in human subjects
Authors: Chien S. , Peng M. T. , Chen K. P. , Huang T. F. , Chang C. , Fang H. S.
Published: December 2017

On 27 men and 6 women, total body density and 10 skinfolds were measured 12 yr apart, with the mean age increasing from 31 to 43 yr. The increase in skinfold thickness was found to be related to the increase in total body adiposity, calculated from hydrostatic weighing. The external adipose tissue was calculated from the mean skinfold thickness and body surface area. Variations in total adiposity among the population studied as well as changes in total adiposity with age showed a characteristic distribution with approximately two-thirds on the surface and one-third in the interior. The essential body mass or total adipose mass determined by hydrostatic weighing was compared with the values obtained by water-immersion volumetry, total body potassium counting, and skinfold measurements. Teh volumetric and skinfold determinations gave better estimates of these parameters than total body potassium counting.
Alveostat, an alveolar PACO2 and PAO2 control system
Authors: Chambille B. , Guenard H. , Loncle M. , Bargeton D.
Published: December 2017

In the study of the physiological regulation of respiration through a control system model it is necessary to test the ventilatory response to various forcing functions of either the parrtial pressure of alveolar carbon dioxide (PACO2) or oxygen (PAO2). Since PACO2 and PAO2 are both functions of alveolar ventilation and metabolic rate, such a result cannot be obtained by merely changing the composition of the inspired gases without a feedback control. Thus a servomechanism is necessary. The input to the servomechanism is an instantaneous determination of PACO2 and PAO2. This is accomplished by using the criterion of equality of the exchange ratio in mean alveolar gas and mean expired gas. The servomechanism described has three essential characteristics: rapidity, accuracy, and stability. In experiments of step, ramp, and sinusoidal forcing functions, variations of PACO2 have been obtained without change in PAO2, and step variations of PAO2 have been obtained without change in PACO2.
Continuous estimation of adipose tissue blood flow in rats by 133Xe elimination
Authors: Madsen J. , Malchow-Moller A. , Waldorff S.
Published: December 2017

A method is described which permits continuous estimation of adipose tissue blood flow (ATBF) in anesthetized female rats. The method is basesd on continuous monitoring of the elimination of 133Xe after labeling of the animal by intraperitoneal injection. From 2 to 6 h after the beginning of the elimination period close to 100% of the measured activity is shown to be located in adipose tissue, mainly in the parametrial fat. About 18% of the elimination is by way of intertissue diffusion, 82% of the perfusing blood. Changes in ATBF can readily be detected. The coefficient of variation for ATBF determinations is 9–11%. Changes in ATBF can be determined with great accuracy. Average ATBF per g tissue for fed and 48-h fasted rats were 0.105 and 0.122 ml-g-1-min-1, respectively. Total ATBF was lower in fasted than in fed rats (1.05 vs. 1.43 ml-min-1 for parametrial plus retroperitoneal fat). Intravenous administration of glucose (250 mg/h) decreased ATBF significantly in fed but not in fasted rats.
Effect of plasma [K+] on the DC potential and on ion distributions between CSF and blood
Authors: Bledsoe S. W. , Mines A. H.
Published: December 2017

Keeping the arterial pH at 7.4 and PaCO2 at 40 mmHg in eight anesthetized dogs, we acutely raised plasma potassium concentration from 3.4 to 8.2 meq/1, then allowed it to decay back to control levels. The cerebrospinal fluid (CSF)-blood electrical potential difference (pd) increased 13.2 mV per 10-fold increase in plasma [K+]. Again keeping arterial pH at 7.4 and PaCO2 at 40 mmHg, we elevated plasma [K+] in four dogs from 3.3 to 8.0 meq/1 and maintained this level for 6 h. We found 1) that the PD increased from a control value of +1.3 to +8.9mV, showing no tendency to decay over the 6 h; and 2) that the change in PD did not affect the distribution of Na+, K+, H+, Cl-, or HCO3- between blood and CSF over the 6 h. These results suggest that under these conditions the PD between CSF and blood may play no effective role in determining the distributions of these charged species by 6 h. These results are contrasted with recent findings which suggest that H+ and HCO3- are distributed according to passive forces between CSF and blood.
A device to measure cutaneous temperature sensitivity in humans and subhuman species
Authors: Kenshalo D. R. , Bergen D. C.
Published: December 2017

A device is described to maintain restricted areas of skin at any temperature between 5 and 45 degrees C. Changes in temperature of controlled intensity up to 10 degrees C at rates from 0.03 degrees C to 2 degrees C/s can be delivered in either the warm or cool directions. The stimulator, which is in contact with the skin, is sufficiently simple so that a number of them can be constructed, each with a different contact area up to 18.2 cm2. The current control apparatus that operates a Peltier device in the stimulator is a feedback control system that maintains a precisely controlled temperature at the stimulator-skin interface. Safety features make it suitable and safe for use in human psychophysical studies and subhuman behavioral measurements of temperature sensitivity. Electrostatic shielding makes it compatible with the electronic instruments used in electrophysiological studies of the temperature sense.
Influence of acute hypertension on aortic valve competence
Authors: Fowler N. O. , Holmes J. C. , Spitz H.
Published: December 2017

The effect of acutely induced hypertension on aortic valve competence was studied in anesthetized dogs. Aortic pressure was increased by infusion of methoxamine or mechanically; aortic valve competence was evaluated by aortogrphy and by indicator dye. The aortic valve was normally competent; aortic insufficiency appeared with increase of mean pressure by as little as 20–50 mmHg; 6 of 9 animals showed aortic incompetence when mean aortic pressure was elevated 45–70 mmHg, but the valve remained competent in 2 of 9 animals with mean pressure increments of 60–90 mmHg. The aortic root was appreciably less distensible than was the proximal descending aorta; this factor may limit the degree of aortic insufficiency in response to acute hypertension in the dog.
Forearm skin and muscle vascular responses to prolonged leg exercise in man
Authors: Johnson J. M. , Rowell L. B.
Published: December 2017

o determine the cutaneous and resting skeletal muscle vascular responses to prolonged exercise, total forearm blood flow (FBF-plethysmography) (5 men) and forearm muscle blood flow (MBF-[125I]antipyrine clearance) (4 men) were measured throughout 55–60 min of bicycle exercise (600–750 kpm/min). Heart rate (HR) and esophageal temperature (Tes) were also measured throughout exercise. FBF showed only small changes during the first 10 min followed by progressive increments during the 10–40 min interval and smaller rises thereafter. For the full 60 min of exercise, there was an average increase in FBF of 8.26 ml/100 ml-min. MBF showed an initial fall with the onset of exercise (on the average from 3.84 to 2.13 ml/100 ml-min) which was sustained or fell further as exercise continued, indicating that increments in FBF were confined to skin. Much of the increase in FBF occurred despite essentially constant Tes. Results suggest that the progressive decrements in central venous pressure, stroke volume, and arterial pressure previously seen during prolonged exercise are due in part to progressive increments in cutaneous blood flow and volume.
Elastic behavior of postmortem human lungs: effects of aging and mild emphysema
Authors: Niewoehner D. E. , Kleinerman J. , Liotta L.
Published: December 2017

The elastic behavior of postmortem human lungs has been studied in an effort to differentiate the effects of normal aging from those of mild emphysema. Static pressure-volume (P-V) curves were measured in 50 lungs obtained from men 15–85 yr of age, including 12 lungs with mild-to-moderate emphysema. The emphysema was quantitatively assessed by gross and microscopic methods. The P-V relationship in all lungs is accurately described by the empirically fitted equation, P = alpha1ea2v. This expression is useful because the two parameters separate the effects of elastic behavior (alpha1) from size (alpha2) on the P-V curve. There is a close negative correlation (R = -0.94) Between age and alpha1 in normal lungs but no significant age dependence of alpha2. Further decreases in alpha1 are found in most emphysematous lungs. Alpha1 is more than 2 SEE below the age-predicted mean in five of nine lungs with minimal emphysema (1–10% by point count) and more than 5 SEE below the mean in the three more severely affected lungs. There is a close correlation (R = +0.90) between alpha1 and the alveolar surface-to-volume ratio in both normal and emphysematous lungs.
In vivo motility of the unobstructed fallopian tube
Authors: Guha S. K. , Talwar G. P.
Published: December 2017

Current methods of recording the fallopian tube motility in vivo essentially measure the intraluminal pressure. Diametral change is another parameter which can provide additional useful information related to tubal function. A method for in vivo monitoring of diametral change without obstructing the lumen and based on the impedance measurement technique has been proposed. An in vitro comparison of wall displacement with transtubal electrical impedance change shows that the impedance changes reflect diametral changes. Another in vitro experiment in which the autorhythmicity of contractions was maintained by means of a perfusion bath indicates that the impedance changes are primarily due to the contraction of the circular muscles of the fallopian tube. These studies were followed up with long-term chronic implantations with dual probes on the isthmic and ampullar regions of the tube in female rabbits. Inpedance changes over periods as long as 6 mo could be readily obtained. Histological observations as well as fertility studies support the conclusion that the tube is minimally affected by the placement of the probes.
Biplane videoroentgenographic analysis of dynamic regional lung strains in dogs
Authors: Chevalier P. A. , Greenleaf J. F. , Robb R. A. , Wood E. H.
Published: December 2017

A method is described for determining the spatial distribution of pulmonary parenchymal strains in the intact canine thorax, using measurements of displacement of metallic (1-mm-diam)) markers percutaneously implanted throughout the parenchyma of the right lung. Dogs are supported head up or head down in a water-immersion respirator with the animal's airway connected to ambient air. Tracking of the parenchymal markers is accomplished by stereo biplane videoroentgenographic recordings, which allow high temporal (60/S) and spatial (+/- 1.5 mm) resolution measurements of the “tagged” lungs during various respiratory maneuvers. After transferring the video information to a stop-action video disc, an operator-interactive computer program is used to input the geometric coordinates of the markers into the computer. The true spatial coordinates are then determined after correction for pincushion and magnification distortions. Spatial and temporal distributions of regional parenchymal strains are obtained by determining the distance between markers on a frame-by-frame basis over the extent of the respiratory cycle. Data indicate nonuniformity in regional lung parenchymal strains.
Effect of hyperinflation on inspiratory function of the diaphragm
Authors: Minh V. D. , Dolan G. F. , Konopka R. F. , Moser K. M.
Published: December 2017

The inspiratory efficiency of the diaphragm during unilateral and bilateral phrenic stimulation (UEPS and BEPS) with constant stimulus was studied in seven dogs from FRC to 120% TLC. Alveolar pressures (PAl) were recorded during relaxation, BEPS and UEPS at each lung volume in the closed respiratory system. From the PAl-lung volume curves, tidal volume (VT), and pressure developed by the diaphragm (Pmus) were derived. Results are summarized below. a) Hyperinflation impaired the inspiratory efficiency of the diaphragm which behaved as an expiratory muscle beyond the lung volume of 103.7% TLC (Vinef). b) The diaphragm during UEPS became expiratory at the same Vinef as during (BEPS. C) The VT-lung volume relationship was linear during BEPS, allowing simple quantitation of VT loss with hyperinflation and prediction of Vinef. d) With only one phrenic nerve stimulated, the functional loss is less pronounced in VT than in Pmus, as compared to BEPS, indicating that the respiratory system was more compliant during UEPS than BEPS. This compliance difference from UEPS to BEPS diminished with severe hyperinflation.
A quantitative description of normal AV nodal conduction curve in man
Authors: Teague S. , Collins S. , Wu D. , Denes P. , Rosen K. , Arzbaecher R.
Published: December 2017

The AV nodal conduction curve generated by the atrial extrastimulus technique has been described only qualitatively in man, making clinical comparison of known normal curves with those of suspected AV nodal dysfunction difficult. Also, the effects of physiological and pharmacological interventions have not been quantifiable. In 50 patients with normal AV conduction as defined by normal AH (less than 130 ms), normal AV nodal effective and functional refractory periods (less than 380 and less than 500 ms), and absence of demonstrable dual AV nodal pathways, we found that conduction curves (at sinus rhythm or longest paced cycle length) can be described by an exponential equation of the form delta = Ae-Bx. In this equation, delta is the increase in AV nodal conduction time of an extrastimulus compared to that of a regular beat and x is extrastimulus interval. The natural logarithm of this equation is linear in the semilogarithmic plane, thus permitting the constants A and B to be easily determined by a least-squares regression analysis with a hand calculator.