bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects ofS-nitroso-N-acetylcysteine on contractile function of reperfused skeletal muscle
Authors: Chen Long-En , Seaber Anthony V. , Nasser Rima M. , Stamler Jonathan S. , Urbaniak James R.
Published: December 2017

The ultimate goal of replantation and microsurgical reconstructive operations is to regain or improve impaired function of the tissue. However, the data related to the influence of NO on tissue function are limited. This study evaluated the effects of the NO donor S-nitroso- N-acetylcysteine (SNAC) on contractile function of skeletal muscle during reperfusion. Forty-nine rats were divided into six groups. The extensor digitorum longus (EDL) muscles in groups I and II were not subjected to ischemia-reperfusion but were treated with a low (100 nmol/min) or high (1 μmol/min) dose of SNAC. In groups III- V, the EDL underwent 3 h of ischemia and 3 h of reperfusion and was also treated with low (100 nmol/min) or high doses (1 or 5 μmol/min) of SNAC. Group VI was a phosphate-buffered saline (PBS)-treated control group. Twenty additional animals were used to document systemic effects of SNAC and PBS only. SNAC or PBS was infused for 6.5 h, beginning 30 min before ischemia and continuing throughout the duration of reperfusion. Contractile testing compared the maximal twitch force, isometric tetanic contractile forces, fatigue, and fatigue half time of the experimental EDL and the contralateral nontreated EDL. The findings indicate that 1) SNAC does not influence contractile function of EDL muscle not subjected to ischemia-reperfusion, 2) SNAC significantly protects the contractile function of ischemic skeletal muscle against reperfusion injury in the early reperfusion period, and 3) the protective role of SNAC is critically dosage dependent; protection is lost at higher doses. The conclusion from this study is that supplementation with exogenous NO exerts a protective effect on the tissue against reperfusion injury.
Renal function and Ca2+currents after dye-labeling identification of renal sympathetic neurons
Authors: Vari Richard C. , Emaduddin Muhammad , Schofield Geoffrey G.
Published: December 2017

The present study was performed to determine whether renal efferent sympathetic neurons could be identified using a retrograde neuronal tracer without compromising renal function and whether the labeling and identification procedure alters Ca2+ currents and neuromodulation of those neurons. Renal sympathetic and superior cervical ganglion (SCG) neurons were labeled with the fluorescent retrograde tracer fast blue. Renal function studies made 1 wk after labeling revealed that renal hemodynamics and fluid and electrolyte excretion were similar between the dye-injected (left) kidney and the control (right) kidney under control conditions and after hemorrhage. After volume expansion, urine flow in the dye-injected kidney was slightly, but significantly, less than that of the control kidney, whereas urinary sodium excretion increased by approximately ninefold in both kidneys. Patch-clamp studies of SCG neurons in 10 mM external Ca2+ revealed that peak currents were not affected by the presence of the dye or a 1-min exposure to ultraviolet (UV) light. Neither maximal norepinephrine-induced Ca2+ current inhibition nor the sensitivity to norepinephrine was affected by the dye or 1-min UV exposure. Facilitation protocols revealed that G protein modulation of Ca2+ currents remained intact in dye-labeled UV-exposed neurons. This study demonstrates that a retrograde fluorescent dye technique to identify renal sympathetic neurons does not compromise renal function and the presence of the dye label or UV exposure has no effect on Ca2+ currents and neuromodulation in these neurons. Isolation of single identified renal sympathetic neurons coupled with patch-clamp techniques represents a tool to investigate the role of individual current systems in the modulation of excitability in these neurons, which play an important role in the control of renal hemodynamics and excretory function and in the pathogenesis of hypertension.
Effects of food deprivation on daily changes in body temperature and behavioral thermoregulation in rats
Authors: Yoda Tamae , Crawshaw Larry I. , Yoshida Kyoko , Su Liu , Hosono Takayoshi , Shido Osamu , Sakurada Sotaro , Fukuda Yutaka , Kanosue Kazuyuki
Published: December 2017

Homeothermic animals regulate body temperature (Tb) by using both autonomic and behavioral mechanisms. In the latter process, animals seek out cooler or warmer places when they are exposed to excessively hot or cold environments. Thermoregulation is affected by the state of energy reserves in the body. In the present study, we examine the effects of 4-day food deprivation on circadian changes in Tb and on cold-escape and heat-escape behaviors in rats. Continuous measurement of Tb during food deprivation indicated that the peak Tb amplitude was not different from baseline values, but the trough amplitude continuously decreased after the onset of food deprivation. Cold-escape behavior was facilitated by food deprivation, whereas heat-escape behavior was unchanged. After the termination of food deprivation, the lowered Tb returned to normal on the first day. However, cold-escape behavior was still facilitated on the third day after food reintroduction. Autonomic and behavioral thermoregulatory effectors are modulated in the face of food shortage so as to maintain optimal performance during the active period, whereas increasing energy conservation occurs during the quiescent phase.
Cholecystokinin and leptin act synergistically to reduce body weight
Authors: Matson Claire A. , Reid Dana F. , Cannon Todd A. , Ritter Robert C.
Published: December 2017

Leptin, the product of the obese gene, reduces food intake and body weight in rats and mice, whereas administration of the gut-peptide CCK reduces meal size but not body weight. In the current experiments, we report that repeated daily combination of intracerebroventricular leptin and intraperitoneal CCK results in significantly greater loss of body weight than does leptin alone. However, leptin plus CCK treatment does not synergistically reduce the size of individual 30-min sucrose meals during this period, and the effect of leptin-CCK combination on daily chow intake, while significant, is small compared with the robust effects on body weight loss. This synergistic effect on body weight loss depends on a peripheral action of CCK and a central action of leptin. These data suggest a previously unsuspected role for CCK in body weight regulation that may not depend entirely on reduction of feeding behavior and suggest a strategy for enhancing the effects of leptin in leptin-resistant obese individuals.
Gβ regulation of Na/H exchanger-3 activity in rat renal proximal tubules during development
Authors: Li Xiao Xi , Albrecht Frederick E. , Robillard Jean E. , Eisner Gilbert M. , Jose Pedro A.
Published: December 2017

The decreased natriuretic action of dopamine in the young has been attributed to decreased generation of cAMP by the activated renal D1-like receptor. However, sodium/hydrogen exchanger (NHE) 3 activity in renal brush-border membrane vesicles (BBMV) can be modulated independent of cytoplasmic second messengers. We therefore studied D1-like receptor regulation of NHE activity in BBMVs in 2-, 4-, and 12-wk-old (adult) rats. Basal NHE activity was least in 2-wk-old compared with 4- and 12-wk-old rats. D1-like agonist (SKF-81297) inhibition of NHE activity was also least in 2-wk-old (−1 ± 9%, n = 3) compared with 4 (−15 ± 5%, n = 6)- and 12 (−65 ± 4%, n = 6)-wk-old rats. The decreased response to the D1-like agonist in BBMV was not caused by decreased D1 receptors or NHE3 expression in the young. Gsα, which inhibits NHE3 activity by itself, coimmunoprecipitated with NHE3 to the same extent in 2-wk-old and adult rats. Gsα function was also not impaired in the young because guanosine 5′- O-(3-thiotriphosphate) decreased NHE activity to a similar extent in 4-wk-old and adult rats. Gαi-3 protein expression in BBMV also did not change with age. In contrast, Gβ expression and the amount of Gβ that coimmunoprecipitated with NHE3 in BBMV was greatest in 2-wk-old rats and decreased with age. Gβ common antibodies did not affect D1-like agonist inhibition of NHE activity in adult rats (8%) but markedly increased it (48%)in 4-wk-old rats. We conclude that the decreased inhibitory effect of D1-like receptors on NHE activity in BBMV in young rats is caused, in part, by the increased expression and activity of the G protein subunit Gβ/γ. The direct regulation of NHE activity by G protein subunits may be an important step in the maturation of renal tubular ion transport.
Prevention of hypoinsulinemia modifies catecholamine effects in fetal sheep
Authors: Bassett John M. , Hanson Clifford
Published: December 2017

Increased epinephrine (Epi) and norepinephrine (NE) production plays an important role in fetal adaptation to reduced oxygen and/or nutrient availability, inhibiting insulin secretion and slowing growth to support more essential processes. To assess the importance of hypoinsulinemia for the efficacy of catecholamines, normoinsulinemia was restored by intravenous insulin infusion (0.18 mU ⋅ kg− 1 ⋅ min− 1) during prolonged infusion of either Epi (0.25–0.35 μg ⋅ kg− 1 ⋅ min− 1for 12 days, n = 7) or NE (0.5–0.7 μg ⋅ kg− 1 ⋅ min− 1for 7 days, n = 6) into normoxemic fetuses in twin-pregnant ewes, from 125–127 days of gestation. Insulin infusion for 8 days during Epi infusion or for 4 days during NE infusion decreased arterial blood pressure, O2 content, and plasma glucose, but increased heart rate significantly (all P <0.05), despite continuation of Epi or NE infusion. Cessation of insulin infusion reversed these changes. Estimated growth of fetuses infused with insulin during Epi or NE infusion (55 ± 13.9 and 83 ± 15.2 g/day) did not differ significantly from that of untreated controls (72 ± 15.4 g/day, n = 6). Growth of selected muscles and hindlimb bones was not altered either. Restoration of normoinsulinemia evidently counteracts the redistribution of metabolic activity and decreased anabolism brought about by Epi or NE in the fetus. Inhibition of insulin secretion by Epi and NE, therefore, appears essential for the efficacy of catecholamine action in the fetus.
Nucleus of the solitary tract lesions enhance drinking, but not vasopressin release, induced by angiotensin
Authors: Schreihofer Ann M. , Stricker Edward M. , Sved Alan F.
Published: December 2017

Rats with chronic nucleus of the solitary tract lesions (NTS-X) drink water and release vasopressin (VP) in response to reduced blood volume despite an absence of neural signals from cardiac and arterial baroreceptors. The present study determined whether rats with NTS-X have a greater sensitivity to circulating ANG II, which may contribute to the drinking and VP responses to hypovolemia. In conscious control rats and rats with NTS-X, ANG II was infused intravenously for 1 h at 10, 100, or 250 ng · kg−1 · min−1. At the two higher doses, ANG II stimulated more water intake with a shorter latency to drink in rats with NTS-X than in control rats. In contrast, infusion of ANG II produced comparable increases in plasma VP in the two groups. At the two higher doses, ANG II produced an enhanced increase in arterial pressure (AP) in rats with NTS-X, and the bradycardia seen in control rats was reversed to a tachycardia. Infusion of hypertonic saline, which did not alter AP or heart rate, produced comparable drinking and VP release in the two groups. These results demonstrate that chronic NTS-X increases the dipsogenic response of rats to systemic ANG II but has no effect on ANG II-induced VP release or the osmotic stimulation of these responses.
Age-related changes in circadian responses to dark pulses
Authors: Duncan Marilyn J. , Deveraux Anthony W.
Published: December 2017

Aging involves many alterations in circadian rhythms, including a loss of sensitivity to both photic and nonphotic time signals. This study investigated the sensitivity of young and old hamsters to the phase advancing effect of a 6-h dark pulse on the locomotor activity rhythm. Each hamster was tested four times during a period of ∼9 mo; periods of exposure to a 14-h photoperiod were alternated with the periods of exposure to constant light (20–80 lx), during which the dark pulses were administered. There was no significant difference in the phase shifts exhibited by the young (4–10 mo) and old hamsters (19–25 mo) or in the amount of wheel running activity displayed during each dark pulse. However, young hamsters had a significantly greater propensity to exhibit split rhythms immediately after the dark pulses. These results suggest that, although aging does not reduce the sensitivity of the circadian pacemaker to this nonphotic signal, it alters one property of the pacemaker, i.e., the flexibility of the coupling of its component oscillators.
Role of area postrema in control of torpor in Siberian hamsters
Authors: Bae Helen H. , Stamper Juliet L. , Heydorn Eric C. , Zucker Irving , Dark John
Published: December 2017

Siberian hamsters undergo torpor during the short days of winter and in response to glucoprivation or food restriction. We tested whether the area postrema and the adjacent nucleus of the solitary tract (hereafter the AP), which monitor metabolic fuel availability, also control the onset of torpor. Siberian hamsters that had manifested torpor spontaneously or had entered torpor in response to 2-deoxy-d-glucose (2-DG) treatment were subjected to area postrema ablations (APx). Hamsters continued to display torpor postoperatively; most features of torpor were unaffected by APx. The AP is not necessary for expression of torpor elicited by short day lengths or metabolic challenge. In contrast, decreases in food intake manifested by hamsters treated with 2-DG were counteracted by APx. In Siberian hamsters, the AP appears to mediate effects of 2-DG on food intake but not torpor.
Regulation of PDGF-beta receptor-operated Ca2+ channels by phospholipase C-gamma 1 in glomerular mesangial cells
Authors: Ma H. , Matsunaga H. , Li B. , Marrero M. B. , Ling B. N.
Published: December 2017

Platelet-derived growth factor (PDGF)-induced Ca2+ signaling mechanisms were examined in cultured rat glomerular mesangial cells. PDGF-BB stimulated the tyrosine phosphorylation of phospholipase C (PLC)-gamma 1, the formation of a PLC-gamma 1/PDGF-beta receptor membrane complex, and the generation of intracellular inositol 1,4,5-trisphosphate (IP3). Preincubation with a tyrosine kinase inhibitor (genistein) abolished these PDGF-induced responses. Activation of 1-pS Ca2+ channels in cell-attached patches by intrapipette PDGF-BB was also abolished by tyrosine kinase inhibition. In the absence of PDGF-BB, channels were activated in cell-attached patches exposed to intrapipette thapsigargin (IP3-independent releaser of intracellular Ca2+ stores) and in excised inside-out patches exposed to increasing “cytoplasmic” Ca2+ (10(-8) to 10(-6) M). In cell-attached patches, channel activation by PDGF-BB was abolished when extracellular Ca2+ was < 1 mM. In glomerular mesangial cells 1) PDGF-BB stimulates tyrosine phosphorylation of PLC-gamma 1, PDGF-beta receptor/PLC-gamma 1 membrane complex formation, IP3 production, and 1-pS Ca2+ channel activity; 2) all four PDGF-induced responses are abolished by tyrosine kinase inhibition; 3) PDGF receptor-operated Ca2+ channels are sensitive to both intra- and extracellular Ca2+.
Measurement of blood flow in kidney and isolated segments of intestine
Authors: Neely William A. , Turner M. D.
Published: December 2017

A method is presented for the determination of blood flow in kidney and isolated intestinal segments. It is essentially a modification of the plethysmographic method of Brodie and Russell ( J. Physiol. 32: xlvii, 1905). The procedure described here avoids the use of anticoagulants or the introduction of devices into the lumen of the vessels concerned. The reproducibility of this procedure is excellent and correlates well with direct cannulation.

Submitted on September 2, 1958
Studies of positive radial acceleration on mice
Authors: Chung Sung Jang
Published: December 2017

One hundred and ninety-one mice were subjected to positive acceleration of from 3 to 85 g, for periods of 5 seconds to 80 minutes. Data on mortality and on pathologic findings are presented. No significant differences were observed in the resistance of male and female mice to positive g. ECG tracings from mice exposed to 8 g for 25 minutes were examined. Formulas are presented to express probability of survival of mice in terms of exposure and magnitude of acceleration stress.

Submitted on May 21, 1958
Measurement of blood flow in minute volumes of specific tissues in man
Authors: Stow Richard W. , Schieve James F.
Published: December 2017

The theory, instrumentation and technique of a thermal method for measuring the blood flow in a small volume of tissue is described. With present instrumentation the volume sampled is about 4 or 5 mm3. The technique has been applied to the relation between tissue temperature and skin blood flow in the calf of the leg. In 25 observations on 3 subjects, values ranging from 1.3 to 82 x 10-4 gm of blood per gm of tissue per second have been obtained. An extension of the technique has led to the measurement of the temperature coefficient of flow, (1/F)(ΔF/ΔT), when flow is influenced by very local temperature changes. A mean value of +39%/° with a range of -57% to +81%/° was found. Periodic fluctuations in tissue temperatures of the frequencies of the heart beat and respiration are described.

Submitted on August 29, 1958
Effect of cooling of orbital cortex on exercise hyperpnea in the dog
Authors: Henry John P. , Whitehorn W. V.
Published: December 2017

The significance of cortical contribution to the hyperpnea of exercise has long been debated. An attempt was made to evaluate the role of this factor by cooling the respiratory area of the orbital cortex in 20 experiments on 13 Nembutal-urethane anesthetized dogs before, during and after electrically induced exercise of the hind limbs. Orbital cooling during eupnea produced a 10% decrease in respiratory rate with questionable reduction of minute volume. Cooling induced during exercise resulted in reduction of mean ventilatory volume from 4.37 l/min. to 4.18 l/min. The difference is highly significant statistically and represents 20% of the exercise hyperpnea under these conditions. Cessation of cooling was followed by return to precooling levels. Results indicate that cortical impulses contribute to exercise hyperpnea even under conditions of anesthesia and low levels of exercise and suggest a quantitative approach to evaluation of this factor under more physiologic conditions.

Submitted on July 21, 1958
Effectiveness of perphenazine and Systral against motion sickness
Authors: Milch Lawrence J. , Frankl Harold D. , Renzi A. A.
Published: December 2017

Perphenazine, a drug with high activity against apomorphine-induced vomiting in dogs, and Systral, an antiemetic analogue of benadryl with little or no activity against apomorphine-induced vomiting in dogs, were tested for antimotion sickness activity in human beings aboard aircraft. Neither furnished any protection. Further, dogs were swing-tested after the administration of chlorpromazine and perphenazine. In spite of the significant difference in protection against apomorphine-induced vomiting afforded by the two drugs (perphenazine much greater than chlorpromazine), perphenazine failed to protect against swing-induced vomiting and chlorpromazine furnished only 25% protection. These data emphasize the unreliability of extending the results of apomorphine inhibition to the relationship of the chemoceptive trigger zone to motion sickness.

Submitted on September 12, 1958
Electroencephalogram and sleep deprivation
Authors: Armington John C. , Mitnick Leonard L.
Published: December 2017

The occipital alpha rhythm was recorded from 10 subjects before, during and after a 98-hour period of sleep deprivation. The alpha rhythm declined progressively and was nearly absent in most subjects after 50 hours of deprivation. At every stage of deprivation the alpha activity was smaller during counting as compared to adding numbers. Stimuli that normally produce alpha block were found to elicit alpha rhythm when the effects of deprivation were apparent. Following deprivation alpha recovered rapidly and within 24 hours was essentially normal.

Submitted on July 23, 1958
Physiological effects of chronic exposure to carbon monoxide
Authors: Wilks Syrrel S. , Tomashefski Joseph F. , Clark Robert T.
Published: December 2017

A group of seven dogs was given a daily 6–8 hour exposure to CO levels of 0.08 to 0.10% for a period of 36 weeks and their tolerance to CO was compared with that of normal dogs, altitude-acclimatized dogs and dogs transfused with blood from normal dogs. The observed increased tolerance to CO was attributed primarily to the increase in concentration of the hemoglobin pigments of the blood. With this increased hemoglobin there was a greater reserve of the pigment for O2 transport at a given concentration level of HbCO. The time required to reach an equilibrium level with a given Pco was greater for the acclimatized than for the normal animals. The PaOO2 was always lower than PaOO2 during the acclimatization period. There was no evidence of factors, other than hematologic, which increased the tolerance of the dogs to CO. Animals subjected to other hypoxic stress such as altitude, or normal animals transfused with normal blood to increase the hematocrit level, showed increased tolerance similar to that accomplished by chronic exposure to low CO levels.

Submitted on September 22, 1958
Effects of pure carbon monoxide gas injection into the peritoneal cavity of dogs
Authors: Wilks Syrrel S.
Published: December 2017

Relatively large quantities of pure carbon monoxide (500 ml) were injected into the peritoneal cavity of normal dogs, CO-acclimatized dogs and altitude-acclimatized dogs. Withdrawal and analysis of the gas at timed intervals revealed a rise in oxygen tension from zero to values which were 2frac12 times the PaOO2. The PiOO2 (intraperitoneal O2 tension) in the acclimatized dogs attained values significantly higher than for the normal dogs. The PiCOCO2 (intraperitoneal CO2 tension) in all dogs approximated the value in normal animals. At no time after the injection did the COHb exceed a 40–50% concentration level. The physiologic mechanism of the observed phenomena is discussed.

Submitted on September 22, 1958
In vitro effect of nonindole compounds on oxidative activity of ceruloplasmin
Authors: Hanson K. M. , Austin D. C. , Aprison M. H.
Published: December 2017

It has already been shown that, in addition to ascorbic acid, 5-hydroxytryptamine and several other 5-hydroxyindole compounds affect the oxidative activity of ceruloplasmin and serum oxidase. Therefore, an in vitro study of the effect of several other normal metabolites and drugs on this enzyme system was undertaken. It was found that the compounds which affect this reaction fall into two classes. One group (cysteine, penicillamine and ascorbic acid) reacts with the oxidized form of the substrate reducing it back into the original compound, thereby producing a lag period in the reaction. The other group (DOPA and iproniazid) inhibits the reaction, probably by competing with the substrate molecules for the enzyme site.

Submitted on November 17, 1958
Local vasodilator action of carbon dioxide on blood vessels of the hand
Authors: Diji A.
Published: December 2017

Immersion of the hand in water saturated with carbon dioxide causes an increase of about 40% in the rate of heat elimination to water at 29℃. This indicates a local vasodilatation of the resistance blood vessels.

Submitted on July 28, 1958
Effect of a vapor barrier on rates of excretion of sweat solutes
Authors: Bass David E. , Mager Milton , Barrueto Richard B.
Published: December 2017

The effects of a vapor-impermeable barrier on rates of excretion of Na, Cl, K, true creatinine and ‘apparent’ creatinine from the arms of men during thermal sweating were determined by collecting sweat solutes simultaneously from both arms, one of which was enclosed in a polyethylene bag. The separate effects on rates of excretion of the higher local skin temperature (Ts) and relative humidity (RH) imposed by a vapor barrier were assessed by means of a thermoregulated arm-chamber. Wearing a vapor barrier resulted in a significantly decreased rate of excretion of K and an increased rate for both true and ‘apparent’ creatinine. The effect on ‘apparent’ creatinine was attributable entirely to the increased excretion of the fraction represented by true creatinine. Rates of excretion of Na and Cl were not significantly affected by the vapor barrier. Increased Ts, per se, resulted in higher excretion rates of Na, Cl, K, true creatinine and urea. Increased RH, per se, led to decreased excretion of Na, Cl, K and urea, but no effect on rate of excretion of true creatinine. The observed effect of a vapor barrier on excretion rates of these sweat solutes was therefore the net result of Ts and RH operating in opposite directions.

Submitted on July 31, 1958
Influence of age on pulmonary diffusing capacity
Authors: Donevan R. E. , Palmer W. H. , Varvis C. J. , Bates D. V.
Published: December 2017

The pulmonary function of 24 normal subjects ranging in age from 20 to 50 years has been studied at rest and during exercise. At rest there is a significant decrease with age in the pulmonary diffusing capacity and the level of diffusing capacity attained on exercise at any particular oxygen uptake decreases with increasing age. Simultaneous measurements of O2 uptake, ventilation, end tidal O2 and CO2 concentration and calculated alveolar CO2 concentration, using the Bohr equation, show no evidence that any of these measurements are significantly influenced by age. The predicted maximal O2 diffusing capacity ( J. Appl. Physiol. 6: 588, 1954) predicts with fair accuracy the diffusing capacity for carbon monoxide that will be found in any given individual at an O2 uptake of about 2.8 l/min. It correctly predicts the change in CO diffusing capacity with increasing age. Reasons are given for suggesting that the decrease in pulmonary diffusing capacity observed may be explained by a diminution in cardiac output with increasing age.

Submitted on November 21, 1958
Possible errors using esophageal balloon in determination of pressure-volume characteristics of the lung and thoracic cage
Authors: Knowles John H. , Hong Suk Ki , Rahn Hermann
Published: December 2017

The static pressure-volume curves of the lung, thoracic cage and total respiratory system were studied in the sitting, supine, prone and knee-elbow position in four subjects. The lung and thoracic-cage pressures were measured with the aid of an esophageal balloon and recorded on a water manometer. The analysis of these various components suggests that in the supine position the esophageal balloon is compressed by the mediastinal content, giving rise to an artifact in the recording of the lung pressure. If this artifact is taken into consideration, it would appear that the effect of posture on the compliance of the lung is negligible. Lung pressures calculated for various lung volumes during active breathing are compared with static values recorded on a water manometer.

Submitted on December 19, 1958
Summation and tetanus in postmortem human heart muscle
Authors: Ullrick William C. , Lentini Eugene A. , Sommers Sheldon C.
Published: December 2017

Induced isometric contractions were recorded from trabeculae carneae from the left ventricles of human hearts obtained at autopsy. Increasing the frequency of stimulation from a driving rate of 1/sec. up to 10/sec. resulted in complete tetanic contractions in the majority of experiments. The tetanic response was usually coupled with summation. The occurrence or nonoccurrence of tetanus was correlated with the contraction time-refractory period ratios.

Submitted on December 16, 1958
Thermal and metabolic responses of the Australian aborigine exposed to moderate cold in summer
Authors: Hammel H. T. , Elsner R. W. , Le Messurier D. H. , Andersen H. T. , Milan F. A.
Published: December 2017

Measurements of thermal and metabolic responses of central Australian aborigines exposed to moderate cold during sleep were repeated during summer and have shown that the small, but important, differences between these natives and control whites exist in summer to the same extent as in winter. The metabolism of the central natives declined continually throughout the night with a Q10 of about two in summer as in winter. Without metabolic compensation, body temperatures of the central natives fell at a greater rate than those of the whites. Measurements of thermal and metabolic responses of a mixed tribal group of tropical Australian aborigines under identical conditions of cold exposure have shown that the average tropical native was intermediate between central natives and control whites. The metabolic rate for tropical natives was 42.8 Cal/m2/hr. compared with 48.7 Cal/m2/hr. for whites and 37.0 Cal/m2/hr. for central natives. We suggest that the Australian aborigine has an inborn ability to tolerate greater body cooling without metabolic compensation which can be increased by prolonged exposure to cold.

Submitted on December 3, 1958
Comparative features of the mechanics of breathing
Authors: Agostoni Emilio , Thimm Frederick F. , Fenn W. O.
Published: December 2017

Dogs, cats, rabbits, guinea pigs and rats have been studied. The lung-thorax compliance per unit body weight and per unit vital capacity shows some significant differences between species. Static pressure required by a normal inspiration is, however, similar in different animals. The expiratory reserve per unit vital capacity and the functional residual capacity per unit total lung capacity are larger in the animals breathing at lower frequency. These findings are related to the hypothesis that animals breathing at lower frequency have a larger functional residual capacity in order to contain within small limits the changes in composition of the alveolar air due to the breathing cycle. Relationship between dynamic pressure and flow follows Rohrer's equation. The dynamic pressure required by a normal ventilation is similar in the different species. Relationship between rate of work of breathing and breathing frequency shows that the frequency typical of each animal is that corresponding to the minimum rate of work.

Submitted on April 13, 1959
Breath-by-breath sampling of end-expiratory gas
Authors: Lambertsen C. J. , Benjamin J. M.
Published: December 2017

An electromechanical method is described for breath-by-breath sampling of gas from the respiratory passages of experimental subjects or from various locations in the breathing apparatus employed. The sampling system includes features permitting the initiation of sampling at different phases of exhalation, initiation of sampling by inspiration and the varying of sampling duration. The breath-by-breath sampling system is shown to be adaptable to physiological and pharmacological studies of spontaneous fluctuations in the composition of end-tidal gas, studies of the rate of change of end-expiratory gas in transitional states and to artificial control of end-tidal pCO2. The magnitude of the pCO2 difference between end-tidal gas and arterial blood is shown to decrease to essentially zero as tidal volume is increased above normal levels.

Submitted on February 11, 1959
Respiratory effects of a calibrated volume-limited pressure-variable ventilator during surgery
Authors: Etsten Benjamin , Reynolds Robert N. , Li T. H.
Published: December 2017

The application of a calibrated volume-limited, pressure-variable ventilator was studied in 34 patients during surgery. Tidal volume and respiratory frequency were determined by means of the Radford nomogram and ventilation was controlled throughout the intra-abdominal and intrathoracic procedures. There was no resistance to the expiratory flow of gases and the recoil of the lung was not impeded during the expiratory phase. The tidal volume was unchanged while the airway pressure varied in relationship to the change of the nonelastic and elastic resistance of the lung-thorax system. The ratio of the duration of the expiratory flow of gas to the duration of the expiratory pause varied in accordance with the changes of the airway resistance and was not altered by the ventilator. This allowed a sufficient duration of the pause period for compensatory circulatory adjustment. Adequate alveolar ventilation was maintained during surgery from 1–6 hours as indicated by the level of the arterial pCO2 (range: 30–48 mm Hg).

Submitted on October 20, 1958
Effect of bronchial and arterial constriction on alveolar gas concentrations in a lobe of the dog's lung
Authors: West J. B. , Hugh-Jones P.
Published: December 2017

Gas concentration tracings were obtained with a mass spectrometer by sampling in the left lower lobe bronchus of open-chested dogs ventilated by a plethysmograph. Partial bronchial obstruction and/or arterial obstruction could be produced by tightening clamps on the bronchus and the branch of the pulmonary artery supplying the lobe. Characteristic patterns of oxygen, carbon dioxide and argon concentration (following a single inspiration of an argon-air mixture) were found with partial bronchial obstruction, arterial obstruction and a combination of both. The patterns were explained by alterations in the ventilation-perfusion ratio and in the phase of ventilation of the obstructed lobe. By relating the tracing taken during mixed obstruction to the pressure cycle of the plethysmograph, some mechanical properties of the obstructed lobe were derived.

Submitted on September 3, 1958
Patterns of gas flow in the upper bronchial tree
Authors: West J. B. , Hugh-Jones P.
Published: December 2017

Patterns of gas flow in the upper bronchial tree have been studied by observing the flow of dye and different gases through a lung cast, and by measurements made on open-chested dogs and on human beings at bronchoscopy. Flow is completely laminar throughout the bronchial tree at low expiratory flow rates (up to 10 l/min.) and completely turbulent, proximal to the segmental bronchi, at high flow rates (80 l/min.). Both at low and high expiratory flow rates, gas from segmental bronchi was not uniformly mixed in the lobar or main bronchi which they supplied. The composition of a catheter sample in these airways would therefore not be representative of the alveolar gas in the corresponding lobe or lung unless the alveolar gas in all areas distal to the sampling tube was homogeneous. Penetration of the left upper lobe bronchus by gas from the lower lobe was demonstrated in the model and a normal subject at bronchoscopy.

Submitted on September 3, 1958
Effects of heat and cold on the albino rat: crossed resistance or crossed sensitization?
Authors: Fleischner Jerry Robert , Sargent Frederick
Published: December 2017

Two experiments were carried out to test whether or not cold-acclimatized rats adjust better to heat and heat-acclimatized rats adjust better to cold than rats not previously exposed to either environmental extreme. In both, groups of rats were exposed to 94.5°–96.5℉ (hot), 33°–40℉ (cold) and 76°–78℉ (control). In the first experiment 45 female Holtzman littermates were used. After 50 days, ‘hot’ rats were abruptly transferred to cold, ‘cold’ rats to heat. Control animals were also placed in each environment. In the second experiment 55 identical rats were similarly treated; the cross, however, was made after 29 days. Rats exposed to 95℉ exhibited sustained hypothermia. Rats exposed to 36℉ developed a transient hypothermia which lasted longer in the first experiment than in the second and was accompanied by more severe cold injury. Heat was not a stress in the sense of Selye, but cold was. There was crossed sensitization rather than crossed resistance.

Submitted on January 26, 1959
Mammary ketogenesis in the cow
Authors: Kronfeld D. S. , Kleiber Max
Published: December 2017

Acetate–2–C14 was injected intracisternally into one quarter of the udder of a normal and of a mildly ketotic cow. The standardized specific activities of fat and ketone bodies in the milk sampled from the injected quarter were greater than those from the noninjected quarter. The percentage of direct udder transfer of C14 was calculated for the normal and ketotic cow, respectively, as 92% and 83% for milk fat, 72% and 94% for beta-hydroxy-butyrate and 80% and 98% for the acetone plus acetoacetate fraction. Total–C14 recovery was decreased in the milk fat, but increased in the milk ketone bodies during ketosis. The results indicated that mammary ketogenesis from acetate occurs in cows and suggested that it is increased during bovine ketosis, probably in association with impaired mammary lipogenesis from acetate. The possible role of coenzymes in bovine ketosis is discussed.

Submitted on June 25, 1959
24-Hour rhythm in susceptibility of C mice to a toxic dose of ethanol
Authors: Haus Erhard , Halberg Franz
Published: December 2017

Male C mice were injected (i.p.) with 0.8 cc of saline or with a 25% ethanol solution in two experiments. In each experiment, separate subgroups of comparable mice were injected at 4-hour intervals during a 24-hour period, under conditions standardized for periodicity analysis. Death rates from ethanol showed a 24-hour rhythm in susceptibility; over 50% of the mice injected in one phase of rhythm died from the injection of a dose of ethanol which barely killed 30% of comparable mice injected in another phase, 12 hours earlier or 12 hours later. In one experiment, ethanol-induced hypothermia was recorded and its degree also was found to be a function of 24-hour rhythm.

Submitted on January 6, 1959
Rate of fall of O2 tension in a lobe of dog lung after bronchial occlusion
Authors: West J. B. , Hugh-Jones P.
Published: December 2017

The oxygen tension in a lobe of the dog's lung following occlusion of the bronchus was measured with a mass spectrometer. The bronchus was rapidly blocked by inflating a small latex balloon just proximal to the tip of the mass spectrometer sampling tube sited in the bronchus. Cannulas in the branch of the pulmonary artery allowed the blood flow to the lobe to be continuously monitored on a rotameter, and direct measurements of flow were made by collection of timed samples. The rate of fall of O2 tension following occlusion was approximately linear initially, and the rate correlated well with the direct measurement of perfusion when the animal was in a steady state. Preliminary trials suggest that the method can be used to compare lobar or segmental perfusion in different parts of the lung in man at bronchoscopy.

Submitted on June 10, 1959
Various degrees of hypothermia in mice
Authors: Blumer W. F. C. , Cole J.
Published: December 2017

Some mice were cooled to a deep body temperature of 15°C, others in ice for an additional 20 minutes to 1°C, still others in ice for 45 minutes to 1°C. The first group showed no impairment on a test for CNS function; the second produced equivocal results; in the third, transitory impairment occurred in skilled mice and in others, slowness in acquiring skill. This third group also showed decrease in weight gain and a mortality rate, especially among the heavier animals. It is inferred that duration as well as intensity of hypothermia is significant, and that a critical point is reached after 20 minutes in ice. Histology revealed no CNS damage.

Submitted on October 27, 1958
Seasonal variation in human amino acid excretion
Authors: Hale Henry B. , Ellis James P. , Van Fossan Donald D.
Published: December 2017

Amino acid excretion was studied in young, healthy men during summer, fall and winter months in a southwestern U. S. location. Both untimed and timed urine samples were employed. The amino acids determined were alanine, arginine, cysteine, glutamic acid, glutamine, glycine, histidine, lysine, methyl histidine, serine, threonine and valine. Supplemental determinations included urine volume, creatinine, uric acid, urea, sodium and potassium. Using untimed urine samples and expressing values as ratios with creatinine, significant seasonal variation was found for alanine, arginine, cysteine, glutamic acid, glycine, lysine and serine.

Submitted on April 11, 1959
Role of pH and thrombin in the PNH hemolytic system
Authors: Auditore Joseph V. , Hartmann Robert C. , Flexner John M.
Published: December 2017

The effect of bovine thrombin on pH-hemolysis curves in paroxysmal nocturnal hemoglobinuria (PNH) was studied. Symmetrical curves demonstrating accentuation of PNH hemolysis by thrombin were obtained. There was no skew toward relative increase in hemolysis at somewhat higher pH values such as might have been anticipated if the mechanism of the thrombin effect was mediated through heterophil antibodies. The buffering effect of small amounts of normal or PNH erythrocytes on acidified serum was studied. The present studies provide no evidence for impaired buffering capacity on the part of the PNH erythrocyte. One of the four PNH patients demonstrated no effect of thrombin on pH-hemolysis curves when autologous cell-serum suspensions were used. However, mixtures of compatible isologous normal or PNH serum with the cells of this patient did demonstrate potentiation of hemolysis when thrombin was added.

Submitted on July 20, 1959
Early effect of moderate altitude stress on plasma potassium in the dog
Authors: Gold Armand J. , Barry Jeanne Q. , Ferguson Frederick P.
Published: December 2017

Exposure of dogs to a simulated altitude of 30,000 feet for 30 minutes resulted in marked respiratory alkalosis and hypokalemia. The data failed to demonstrate, however, the appearance of the early transient hyperkalemic response which has been observed in human beings in the early moments of hyperventilation. Blood pH rose from an initial level of 7.46 to 7.71 after 3 minutes of exposure to altitude. At 30 minutes it had declined slightly from this maximal level to 7.63, suggesting the development of partial compensation to respiratory alkalosis. The results also indicated a temporal potassium-glucose relationship, potassium decreasing and glucose increasing simultaneously during exposure to altitude.

Submitted on July 13, 1959
Pulmonary vascular resistance and vascular transmural gradient
Authors: Lloyd Thomas C. , Wright George W.
Published: December 2017

Perfusion studies were made on vascular beds of isolated dog lungs. Submerged, gas-free, fluid-distended lobes served for studies of resistance versus transmural pressure in a technique that abolished gravitational effects. Air-distended lobes with varying degrees of pulmonary edema were used to display the transmural gradient differences produced by height, and the effect alveolar fluid has on the apparent transmural gradient. Results indicate that the vascular bed behaves as a compliant tube of a limited maximal radius to which it may be distended while still in the normal pressure range. Vasopressors influence the wall distensibility and thus only the lower pressure portion of a pressure-flow curve. Flow continues through lobes distended at higher than arterial pressures with air. Progressive disappearance of this phenomenon as intra-alveolar fluid collects suggests that the effective transmural gradient differs from the vascular-alveolar gradient and is in part a function of alveolar surface tension.

Submitted on October 16, 1959
Effect of acceleration on blood creatine, creatinine and inorganic phosphorus in man
Authors: Slonim Arnold R.
Published: December 2017

Ten healthy male subjects were centrifuged front to back at 6 g for 3 min., with head and trunk inclined 25 degrees forward in the direction of acceleration. Average control values of blood creatine, creatinine and inorganic phosphorus were almost identical to those found immediately after exposure to the acceleration. Relatively large differences (test minus control) in some individuals were not significant. Acceleration of the magnitude and/or duration used in this study does not appear to be comparable to the effects of vigorous exercise on the phosphocreatine system of man.

Submitted on July 23, 1959
Mechanical efficiency of breathing
Authors: Milic-Emili G. , Petit J. M.
Published: December 2017

Simultaneous measurements of mechanical work and energy cost of breathing were performed on four normal subjects with ventilation increased by adding dead space. Mechanical work was obtained from simultaneous records of endoesophageal pressure and tidal volume. The associated energy cost was estimated by measuring oxygen consumption of respiratory muscles by means of a closed-circuit spirometer. In all subjects studied and over the range of ventilations involved (ca. 30–110 l/min.), the mechanical efficiency of breathing was found to be in the order of 0.19–0.25.

Submitted on July 6, 1959
Effect of body composition and weight gain on performance in the adult dog
Authors: Young D. R.
Published: December 2017

The effect of overfeeding and variations in body composition on resting metabolism and work performance has been examined in the adult dog. At rest, the mean O2 uptake was 85.5 cc/min. and the R.Q. was .65. These were not substantially altered by 20% gain in weight associated with variations of 12%–20% in body fat content. Work performance was tested during a 50-min. period of treadmill running at a fixed work intensity of 202.9 kg-m/min. Oxygen uptake, work and recovery pulse rates were constant. However, the respiratory quotient increased from .81 to .95 and water loss during work increased from 1.16 cc/Cal. to 1.84 cc/Cal. with gain in weight and adiposity. It is concluded that the most important effect of gain in weight is to promote increased water loss during constant steady-state work.

Submitted on December 11, 1959
Electric response in the mammary gland
Authors: Forbes Alexander , Neyland Marjorie , Fox Sally
Published: December 2017

Our previous investigations have indicated that ‘let-down’ sensation in the mammary gland in nursing, or on injection of Pituitrin, is accompanied by slow electric response. This was believed to emanate from secreting-gland cells or from contractile myoepithelial cells. Indirect control indicated that sweat-gland activity, related to emotional reaction, played little part in electric response recorded from the breast. We have controlled this question of sweat-gland participation in observed response by recording simultaneously from the palm of the hand and from the areola in a non-lactating subject. It was found that spoken words evoking emotional reactions were accompanied by large electric responses from the palm, but from the areola there were either no responses or very small inverse deflections, presumably due to sweat glands in the skin of the thorax. Observations on lactating subjects showed that during nursing occasional deflections in the palmar record resembled those evoked in word tests, but in no case did the palmar record show a slow response synchronized with that recorded from the areola during the letdown. From these observations we conclude that sweat-gland reactions play little part in the characteristic let-down electric response led off from the areola. This must arise from a different source, presumably either the myoepithelial cells, the secreting cells, or both.

Submitted on January 14, 1960