bluuebunny/crossref_metadata_2025 huggingface dataset:
Central actions of adrenomedullin on cardiovascular parameters and sympathetic outflow in conscious rats
Authors: Saita Mitsuhiko , Shimokawa Ayumi , Kunitake Takato , Kato Kazuo , Hanamori Takamitsu , Kitamura Kazuo , Eto Tanenao , Kannan Hiroshi
Published: December 2017

Adrenomedullin (ADM) is reported to be a peripherally acting hypotensive peptide, but its central actions are unclear. We investigated the effects of centrally administered ADM on blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) in conscious rats and sinoaortic-denervated (SAD) rats. We also investigated the receptors interacting with ADM using two putative antagonists. Intracerebroventricular administration of ADM in doses of 0.1 and 0.5 nmol/kg caused tachycardia and early inhibition of RSNA. Central ADM (1.0 nmol/kg) induced hypertension, tachycardia, and a decrease followed by an increase in RSNA. In SAD rats, increases in BP, HR, and RSNA at the late phase were enhanced by central ADM (1.0 nmol/kg), whereas the early decrease in RSNA remained. Thus the inhibition of RSNA via central ADM may be unrelated to the arterial baroreceptor reflex. Pretreatment with antagonists human calcitonin gene-related peptide-(8—37) and human ADM-(22—52) significantly suppressed the central actions of ADM. The findings suggest that ADM is involved as a neuropeptide in the receptor-mediated central regulation of the cardiovascular system and RSNA.
Pudendal nerve stimulation induces urethral contraction and relaxation
Authors: le Feber Joost , van Asselt Els
Published: December 2017

In this study we measured urethral pressure changes in response to efferent pudendal nerve stimulation in rats. All other neural pathways to the urethra were transected, and the urethra was continuously perfused. We found fast twitch-like contractions, superimposed on a slow relaxation. The amplitude of the twitches was independent of the stimulation frequency below 26 Hz, whereas the relaxation depended highly on this frequency. The twitches were caused by striated urethral muscles, and the relaxation was caused by smooth muscles. Both were mediated by acetylcholine. We calculated the effective urethral relaxation as the absolute relaxation multiplied by the time fraction between the twitches. Maximum effective relaxation occurred at 8–10 Hz, exactly the frequency of spontaneous oscillations during bladder voiding in rats. Although the oscillatory sphincter contractions in rats during voiding may be needed in other mechanisms for efficient voiding, our data suggest that they may be a side effect of the actual purpose: urethral relaxation.
Feeding-entrained circadian rhythms in hypophysectomized rats with suprachiasmatic nucleus lesions
Authors: Davidson Alec J. , Stephan Friedrich K.
Published: December 2017

Several pituitary hormones are important in the regulation of metabolism, and their release appears to be controlled by a circadian clock. Consequently, they may be involved in feeding-entrained circadian rhythms. Hypophysectomized (Hypox) and sham-operated male Sprague-Dawley rats had access to food for 4 h each day. Food-anticipatory activity (FAA) and core body temperature (Tb) were monitored. Both groups entrained to the daily meal with an increase in activity in the 4 h preceding meal access and quickly reentrained after an 8-h phase advance of food access. FAA was not disrupted in either group after suprachiasmatic lesions were added. Core Tb increased in the sham-operated subjects before mealtime, but Hypox rats failed to show this effect. Rather, Tb declined during anticipation and throughout the food access period. Respiratory quotient (RQ), an indirect measure of metabolic rate, was measured for 24 h in some subjects. Sham-operated rats showed a dramatic downturn in RQ 1 h before mealtime, whereas Hypox rats showed a steadily decreasing RQ throughout the day. The results show that the pituitary hormones are not necessary for FAA and that in Hypox rats the anticipatory rise in Tb and changes in RQ become dissociated from anticipatory behavior, indicating that these functions are separate outputs of the food-entrainable circadian oscillator.
Aging does not contribute to the decline in insulin action on storage of muscle glycogen in rats
Authors: Gupta Gaurav , She Li , Ma Xiao-Hui , Yang Xiao-Man , Hu Meizhu , Cases Jane A. , Vuguin Patricia , Rossetti Luciano , Barzilai Nir
Published: December 2017

Increase in fat mass (FM) and changes in body composition may account for the age-associated impairment in insulin action on muscle glycogen storage. We wish to examine whether preventing the increase in FM abolishes this defect seen with aging. We studied the novel aging model of F1 hybrids of BN/F344 NIA rats fed ad libitum (AL) at 2 (weighing 259 ± 17 g), 8 (459 ± 17 g), and 20 (492 ± 10 g) mo old. To prevent the age-dependent growth in FM, rats were caloric restricted (CR) at 2 mo by decreasing their daily caloric intake by 45% (weighing 292 ± 5 g at 8 mo, 294 ± g at 20 mo). As designed, the lean body mass (LBM) and %FM remained unchanged through aging (8 and 20 mo old) in the CR rats and was similar to that of 2-mo-old AL rats. However, 8- and 20-mo-old AL-fed rats had three- to fourfold higher FM than both CR groups. Peripheral insulin action at physiological hyperinsulinemia was determined (by 3 mU ⋅ kg−1 ⋅ min−1insulin clamp). Prevention of fat accretion maintained glucose uptake (Rd; 29 ± 2, 29 ± 2, and 31 ± 4 mg ⋅ kg LBM−1 ⋅ min−1) and glycogen synthesis rates (GS, 12 ± 1, 12 ± 1, and 14 ± 2 mg ⋅ kg LBM−1 ⋅ min−1) at youthful levels (2 mo AL) in 8- and 20-mo-old CR rats, respectively. These levels were significantly increased ( P < 0.001) compared with AL rats with higher %FM (Rd, 22 ± 1 and 22 ± 2 and GS, 7 ± 1 and 8 ± 2 mg ⋅ kg LBM−1 ⋅ min−1in 8- and 20-mo-old rats, respectively). The increase in whole body GS in age-matched CR rats was accompanied by ∼40% increased accumulation of [3H]glucose into glycogen and a similar increase in insulin-induced muscle glycogen content. Furthermore, the activation of glycogen synthase increased, i.e., ∼50% decrease in the Michaelis constant, in both CR groups ( P < 0.01). We conclude that chronic CR designed to prevent an increase in storage of energy in fat maintained peripheral insulin action at youthful levels, and aging per se does not result in a defect on the pathway of glycogen storage in skeletal muscle.
Interstitial K+ in human skeletal muscle during and after dynamic graded exercise determined by microdialysis
Authors: Juel C. , Pilegaard H. , Nielsen J. J. , Bangsbo J.
Published: December 2017

Interstitial K+ concentrations were measured during one-legged knee-extensor exercise by use of microdialysis with probes inserted in the vastus lateralis muscle of the subjects. K+ in the dialysate was measured either by flame photometry or a K+-sensitive electrode placed in the perfusion outlet. The correction for fractional K+ recovery was based on the assumption of identical fractional thallium loss. The interstitial K+ was 4.19 ± 0.09 mM at rest and increased to 6.17 ± 0.19, 7.48 ± 1.18, and 9.04 ± 0.74 mM at 10, 30, and 50 W exercise, respectively. The individual probes demonstrated large variations in interstitial K+, and values >10 mM were obtained. The observed interstitial K+ was markedly higher than previously found for venous K+ concentrations at similar work intensities. The present data support a potential role for interstitial K+ in regulation of blood flow and development of fatigue.
Lipopolysaccharide effects on neuronal activity in rat basal forebrain and hypothalamus during sleep and waking
Authors: Xi Xinzheng , Toth Linda A.
Published: December 2017

Peripheral administration of lipopolysaccharide (LPS) is associated with alterations in sleep and the electroencephalogram. To evaluate potential neuronal mechanisms for the somnogenic effects of LPS administration, we used unanesthetized rats to survey the firing patterns of neurons in various regions of rat basal forebrain (BF) and hypothalamus during spontaneous sleep and waking and during the epochs of sleep and waking that occurred after the intraperitoneal administration of LPS. In the brain regions studied, LPS administration was associated with altered firing rates in 39% of the neurons examined. A larger proportion of LPS-responsive units showed vigilance-related alterations in firing rates compared with nonresponsive units. Approximately equal proportions of LPS-responsive neurons showed increased and decreased firing rates after LPS administration, with some units in the lateral preoptic area of the hypothalamus showing particularly robust increases. These findings are consistent with other studies showing vigilance-related changes in neuronal activity in various regions of BF and hypothalamus and further demonstrate that peripheral LPS administration alters neuronal firing rates in these structures during both sleep and waking.
Disorder of salivary secretion in inbred polydipsic mouse
Authors: Hamada Akiko , Inenaga Kiyotoshi , Nakamura Shuichi , Terashita Masamichi , Yamashita Hiroshi
Published: December 2017

To find mechanisms of an extreme polydipsia in an inbred strain of mice, STR/N, this study was undertaken using Institute of Cancer Research (ICR) mice as a control. During food deprivation, daily water intake of both strains decreased. The decrement in the STR/N mice was larger than that in the ICR mice. During dehydration, daily food intake of the STR/N mice was smaller than that of the ICR mice. These data indicate that prandial drinking was more severely affected for the STR/N mice. Under anesthesia, the stimulated salivary secretion by pilocarpine of the STR/N mice was significantly smaller than that of the ICR mice. The submandibular gland of the STR/N mice was lighter and harder than that of the ICR mice. After desalivation from the major three salivary glands, the ICR mice drank as much as the STR/N mice. Young STR/N mice with undeveloped polydipsia did not show different salivary secretion stimulated by pilocarpine from the young ICR mice. These findings indicate a dysfunction with age in the salivary glands of the STR/N mice, and they suggest that the decreased saliva induces thirst and triggers extraordinary drinking in the polydipsic mice.
Enhanced pressor response to carotid occlusion in commNTS-lesioned rats: possible efferent mechanisms
Authors: Sato Monica Akemi , Menani José Vanderlei , Lopes Oswaldo Ubríaco , Colombari Eduardo
Published: December 2017

Bilateral common carotid occlusion (BCO) over a period of 60 s in conscious rats produces a biphasic pressor response, consisting of an early (peak) and late (plateau) phase. In this study we investigated 1) the effects of lesions of the commissural nucleus of the solitary tract (commNTS) on the cardiovascular responses produced by BCO in conscious rats and 2) the autonomic and humoral mechanisms activated to produce the pressor response to BCO in sham- and commNTS-lesioned rats. Both the peak and plateau of the pressor response produced by BCO increased in commNTS-lesioned rats despite the impairment of chemoreflex responses induced by intravenous potassium cyanide. In sham rats sympathetic blockade with intravenous prazosin and metoprolol, but not vasopressin receptor blockade with the Manning compound, reduced both components of BCO. In commNTS-lesioned rats the sympathetic blockade or vasopressin receptor blockade reduced both components of BCO. The results showed 1) the sympathetic nervous system, but not vasopressin, is important for the pressor response to BCO during 60 s in conscious sham rats; 2) in commNTS-lesioned rats, despite chemoreflex impairment, BCO produces an increased pressor response dependent on sympathetic activity associated with vasopressin release; and 3) the increment in the pressor response to BCO in commNTS-lesioned rats seems to depend only on vasopressin secretion.
Brain-blood permeability: TNF-α promotes escape of protein tracer from CSF to blood
Authors: Dickstein Jodi B. , Moldofsky Harvey , Hay John B.
Published: December 2017

The objective of this study was to determine the effect of tumor necrosis factor (TNF)-α on the efflux of protein from the central nervous system to blood based on assessing the clearance of radiolabeled albumin from the cerebrospinal fluid (CSF) to blood in rats. 125I-labeled human serum albumin (125I-HSA) was injected into a lateral ventricle, and venous blood was sampled hourly to determine the basal CSF protein clearance into the blood. After this, rats were intraventricularly infused with 10 μl TNF-α and 10 μl131I-HSA ( n = 6) or 10 μl saline and 10 μl 131I-HSA ( n = 6). Venous blood was sampled hourly for 3 h. 131I-HSA tracer recovery increased threefold in the venous blood and was significantly higher in the spleen, muscles, and skin in animals treated with TNF-α. No significant changes were observed in control animals treated with saline. The data suggest that TNF-α promotes the clearance of protein macromolecules from the CSF to the venous blood.
Effects of angiotensin II on regional afferent and efferent arteriole dimensions and the glomerular pole
Authors: Denton Kate M. , Anderson Warwick P. , Sinniah Raja
Published: December 2017

The diversity of renal arteriole diameters in different cortical regions has important consequences for control of glomerular capillary pressure. We examined whether intrarenal angiotensin II (ANG II; 0.1, 1, or 5 ng · kg−1 · min−1) in anesthetized rabbits acts preferentially on pre- or postglomerular vessels using vascular casting. ANG II produced dose-related reductions in afferent and efferent diameters in the outer, mid, and inner cortex, without effecting arterial pressure. Afferent diameter decreased more than efferent in the outer and mid cortex ( P < 0.05) but by a similar extent in juxtamedullary nephrons ( P = 0.58). Calculated efferent resistance increased more than afferent, especially in the outer cortex (127 vs. 24 units; 5 ng · kg−1 · min−1 ANG II). ANG II produced significant dose-related increases in the distance between the arterioles at the entrance to the glomerular pole in all regions. Thus afferent diameter decreased more in response to ANG II, but efferent resistance rose more due to smaller resting luminal dimensions. The results also indicate that glomerular pole dimensions change in response to ANG II.
Effect of continuous cold exposure on nocturnal body temperatures of man
Authors: Kreider M. B. , Iampietro P. F. , Buskirk E. R. , Bass David E.
Published: December 2017

Effects of continuous cold stress on 24-hour patterns of body temperature were studied in five men. Cold stress consisted in living at 15.6℃ (60℉) for 14 days wearing only shorts. The cold period was preceded and followed by 2 weeks at 26.7℃ (80℉). Activity (minimal) and diet were the same for all periods. One blanket was used at night. Rectal temperature (Tr) and skin temperature (Ts) were measured. Tr during sleep fell more rapidly and to lower values during cold exposure (35.6℃) than during the control period (36.1℃). Ts during sleep was slightly lower in the cold than in the control period; also, Ts did not exhibit the gradual drop characteristic of sleep in the control period. Comparison of Tr and Ts between early and later cold days revealed the following differences: a) nocturnal Tr fell to lower levels on the later cold days; b) nocturnal toe temperatures were 15℃ (27℉) higher on the later cold days. The arch temperatures followed the same pattern as the toes. No significant differences were found in daytime temperatures between early and later cold days. The data suggest that evidence for acclimatization to cold in terms of altered body temperature responses may be fruitfully sought in responses during rewarming and/or sleep.

Submitted on September 19, 1958
Static volume-pressure interrelations of the lungs and pulmonary blood vessels in excised cats' lungs
Authors: Frank N. Robert , Radford Edward P. , Whittenberger James L.
Published: December 2017

Measurements were made of the effect of pulmonary vascular distention on static volume-pressure relations of excised cats' lungs filled either with saline to minimize surface forces, or inflated with gas. Only slight changes of questionable significance occurred in elastic behavior of the lungs during deflation when pulmonary vascular pressure was increased from 0 to 16 cm H2O. Measurements were also made of quasi-static pulmonary vascular volume-pressure relations at different lung volumes. The overall slope of the vascular volume-pressure curve in saline-filled lungs was greatest at a moderate lung volume and was slightly less when the lungs were either collapsed or highly distended. The vascular volume-pressure curve was considerably flattened in gas-inflated lungs at airway pressures above 10 cm H2O. During filling and emptying of the vascular system there were slight but definite changes in equilibrium volume of the lung. Hysteresis of the vascular system was an invariable finding. Regardless of the complex mechanism underlying hysteresis, it can be explained if all units of the system are assumed to have sigmoid volume-pressure curves. The findings of these experiments illustrate the highly complex interrelations of the pulmonary blood vessels and lungs, particularly when surface forces are taken into account.

Note:

(With the Technical Assistance of Martha McLaughlin)

Submitted on May 29, 1958
Pulmonary mechanics during induced pulmonary edema in anesthetized dogs
Authors: Cook C. D. , Mead J. , Schreiner G. L. , Frank N. R. , Craig J. M.
Published: December 2017

In order to study the mechanisms underlying the changes in the mechanical properties of the lungs during pulmonary edema, pulmonary vascular congestion was produced in spontaneously breathing, anesthetized dogs by partial aortic obstruction and intravenous infusion. Brief periods of congestion were associated with small changes in the lung compliance compared with the progressive and striking compliance reduction (-78%) noted with more prolonged congestion. Lung volume at end-expiration showed little change if edema fluid and trapped gas as well as the ventilated gas volume were taken into account. When edematous lungs were forcibly inflated beyond the tidal range, it was found that the overall compliance at a distending pressure of 30 cm H2O was not much less (-6%) than that of normal lungs. Furthermore, edematous lungs manifested marked ‘static’ hysteresis during such maneuvers. These findings suggested that surface phenomena were responsible for the mechanical behavior of edematous lungs rather than vascular congestion, per se, or intrinsic tissue changes. This was borne out by experiments on excised lungs which showed that the elastic properties of edematous lungs were not significantly different from normal lungs when surface forces were minimized.

Submitted on August 25, 1958
Some factors which are correlated with swimming capacity in guinea pigs
Authors: Wilber Charles G.
Published: December 2017

Guinea pigs were forced to swim to exhaustion under various experimental conditions. Electrocardiograms taken on some animals showed T waves with high amplitude and take-off. Ventricular fibrillation was never observed. The length of swim in guinea pigs varied inversely with the logarithm of the rate of change of rectal temperature. Liver glycogen was found to decrease markedly after forced swimming. Blood glucose values showed no clear pattern of change. Blood lactic acid values at termination were elevated by at least 50 mg/100 ml. Swimming time was found to vary inversely with the logarithm of the rate of change of blood lactic acid. Swimming time was decreased significantly if the animals were forced to bear a load. At 20° and 30℃ bath temperature, the ST50 (reduction of swimming time to 50% of control) was obtained with a load equal to about 2.5% of the body weight. If guinea pigs were forced to swim in groups rather than alone, about 70% showed a decrease of at least 50% in expected swimming time. It is suggested that small mammals should be forced to swim singly rather than in groups to obtain precise results.

Submitted on July 30, 1958
Renal circulatory occlusion and local cooling
Authors: Birkeland S. , Vogt A. , Krog J. , Semb C.
Published: December 2017

A method was developed for local kidney cooling in vivo, evaluated in dogs and applied clinically. In dogs a reversible lesion was not obtained if renal ischemia lasted beyond 1 hour at 37℃. Application of local cooling (10±5℃) extended the tolerance time to 7 hours, with clamping of the entire renal pedicle, and to 12 hours with occlusion of the renal artery alone. Exposure of the same kidney to a second occlusion period (up to 9 hr.) resulted in a reversible lesion. Renal function studies (CU, CIn, CPAH and TmPAH) showed the same pattern (initial depression and course of recovery) as after renal ischemia at body temperature. Initial depression was roughly paralleling the duration of clamping. Preischemic function values were, in most instances, reached 3 months following the experimental procedure. Physiological aspects of ‘local cooling’ are discussed and the advantages over general hypothermia are pointed out. The technique used for clinical application is described.

Submitted on April 25, 1958
Comparison between alveolo arterial gradient predicted from mixing studies and the observed gradient
Authors: Briscoe William A.
Published: December 2017

The component of the A-a gradient due to uneven V/Q ratios would average 9 mm in 18 studies on six normal subjects if the observed uneven ventilation coexisted with even perfusion of the lung. This component constitutes the largest part of the A-a oxygen gradient of the resting man breathing air. In cases where the A-a gradient, predicted on the basis of helium mixing studies and the assumption of even perfusion, exceeds the observed total gradient, there must be either an error in the measurements or else the less ventilated alveoli must be underperfused with blood. In a group of eight subjects with cardiopulmonary dysfunction, the A-a gradient predicted from the helium mixing studies averaged 23 mm, with a range of 5–65 mm. The measured total gradient averaged 25 mm, a nonsignificant difference. Comparison with total measured A-a oxygen gradient is difficult because, this gradient is underestimated to a variable degree when computed on the assumption that arterial and alveolar CO2 tensions are the same. It is clear, however, that the predicted component due to uneven Va/Qc ratios accounts for the largest part of the total observed A-a gradient.

Submitted on October 3, 1958
Influence of vagal blockade on respiratory work in the hypoxic and hypercapneic anesthetized dog
Authors: Salzano John , Hall F. G.
Published: December 2017

The mechanical work of breathing was determined in anesthetized dogs by measurements of intrathoracic pressures and tidal volumes, during inhalation of various gas mixtures while vagi reflexes were functional (warm) and blocked (cool). Pressure-volume loops obtained when vagi reflexes were blocked showed that both elastic and viscous work per breath increased during inhalation of 3.8% and 5.2% CO2. However, the total work per minute increased during inhalation of 3.8% CO2, but remained constant during inhalation of 5.2% CO2. During inhalation of 10.1% O2 in nitrogen, viscous and elastic work per breath increased when vagi were blocked, with no significant changes in total work per minute. When 6.39% O2 in nitrogen was inhaled, elastic and viscous work per breath increased with blocked vagi, but a significant decrease in total work per minute occurred. Vagal reflexes do not have as prominent a role in influencing the work of breathing during severe hypoxia and hypercapnia as they do during normal and obstructive breathing.

Submitted on November 20, 1958
Tracking proficiency as a function of thermal balance
Authors: Payne Robert B.
Published: December 2017

An experiment was conducted for the purpose of learning a) whether or not performance decrement in monitoring and controlling a complex visual display is related to body heat loss and b) whether or not such an impairment can be forestalled by glycine administration. Following extensive training on the experimental task, 72 subjects were independently and randomly assigned to the 9 combinations of 3 ambient temperature conditions (70°, 55° and 40℉) and 3 glycine treatments (0, 20 and 40 gm), then required to execute a performance sequence lasting 3 hours and 20 minutes. Statistical analyses established that the mathematical function relating performance to temperature was a parabola having a maximum near 55°. No significant glycine effects were observed.

Submitted on September 25, 1958
Effect of rhythmically inflating a pneumatic cuff at the ankle on blood flow in the foot
Authors: Loane R. Andrew
Published: December 2017

Rhythmic inflation to 110 mm Hg of a pneumatic cuff around the ankle of a seated subject reduces the venous pressure in the foot and is found by three methods, venous occlusion plethysmography, heat flow and calorimetry, to increase the rate of blood flow through the foot. The increases measured by the three methods are not, however, in quantitative agreement and it is not possible to decide how large the increase may be. It is considered, however, that the increase in flow is probably of the same order as the increase in perfusion pressure and not greatly in excess of this increase.

Submitted on August 5, 1958
Electrical activation and mechanical asynchronism in the cardiac cycle of the dog
Authors: Samet Philip , Bernstein William H. , Litwak Robert S. , Meyer William H. , Lemberg Louis
Published: December 2017

Dissociation of electrical and mechanical asynchronism in the right and left ventricle of the dog has been studied by simultaneous registration of the precordial electrocardiogram and right and left ventricular pressure curves. Observations were made during sinus rhythm and during digitalis-induced ventricular premature beats with widened aberrant QRS complexes. Measurements were made of the time of onset of isometric contraction in the ventricles, relative to each other, and to the onset of the QRS complex. The results indicate that mechanical asynchronism in onset of isometric contraction is not a necessary consequence of the asynchronous electrical depolarization of ventricular premature systoles.

Submitted on November 10, 1958
Passive antibody decay in rabbits under cold or altitude stress
Authors: Trapani Ignatius L. , Campbell Dan H.
Published: December 2017

Rabbits maintained at an environmental temperature of -15℃ (5℉) for 10 weeks exhibit an increase in the decay rate of passively administered antibody. Rabbits acclimatized at an altitude of 12,470 feet for 30 days show little or no change in passive antibody decay. Protein turnover in these groups of animals is discussed.

Submitted on October 27, 1958
Design of a body plethysmograph for studying cardiopulmonary physiology
Authors: Comroe Julius H. , Botelho Stella Y. , DuBois Arthur B.
Published: December 2017

A body plethysmograph may be used for the measurement in man of thoracic gas volume, airway resistance, instantaneous pulmonary capillary flow and abdominal gas volume; if functional residual capacity (dilution method) and pulmonary resistance (esophageal balloon technique) are measured concomitantly, calculations of ‘trapped’ gas (in the lungs or pleural cavity) and of pulmonary tissue resistance may also be made. The design of the plethysmograph, the electrical circuits and recording devices used and the direct reading attachments for the cathode ray oscillograph are presented together with details of operation and some suggestions for modifications of the original design.

Submitted on July 14, 1958
Estimation of pulmonary ventilation with nitrogen and helium, using the mass spectrometer
Authors: Tokuyasu K. , Coblentz A. , Bierman H. R.
Published: December 2017

Estimation of pulmonary ventilation was attempted by measuring the elimination of nitrogen and helium with the mass spectrometer. Exhalatory concentrations of nitrogen and helium were continuously recorded in each of 12 normal subjects and 10 patients with pulmonary enphysema or space-occupying pulmonary lesions. Uniform values for both slow and rapid uneven ventilation were found in all normal subjects but always less than in emphysematous states. Ratios of effective tidal volume (Vt) and alveolar ventilation volume (f·Vt) to functional residual capacity P = Vt/Vr and Q = f·Vt/Vr were one half or less than those in the normal subject. Smaller values of uneven ventilation were found for helium than nitrogen. Data computed by the theory of 'periodic' ventilation gave greater values for uneven ventilation (Q) and more accurately represented the physiologic conditions than derived by ‘continuous’ ventilation.

Submitted on August 7, 1958
Course of mercurial diuresis during Pitressin infusion in mild congestive heart failure
Authors: Grossman Jacob , Gibbons Donald , Weston Raymond E.
Published: December 2017

In an attempt to assess the influence of diminished filtration rate on the renal response to a mercurial diuretic, with particular emphasis on anisosmotic (free) water reabsorption, six patients with mild congestive failure were given Mercaptomerin, 2 ml, i.v., while receiving a constant infusion of Pitressin 2 μ/kg/hr. During the control collection periods, the anisosmotic water reabsorption was less than that encountered previously in a group of normal subjects. With the onset of diuresis, free water reabsorption rose to the same levels as that of normal individuals and, thereafter, followed the same course. The changes observed are compatible with the hypothesis that free water reabsorption is limited by either of two factors, at low flows, the concentration gradient along the tubule and, at higher flows, the maximal ability of the anisosmotic segment to reabsorb water at a given level of hydration and antidiuretic activity.

Submitted on November 13, 1958
Release of intracellular potassium as the physiological stimulus for pain
Authors: Benjamin Fred B.
Published: December 2017

Evidence is presented that various types of pain-producing stimuli also release intracellular potassium, and that potassium is a pain-producing stimulus. If the potassium releasing process is inhibited or neutralized by calcium, or reversed by increasing cellular uptake of potassium by means of a glucose-insulin combination, the response to painful stimuli is decreased. Calcium appears to have a more immediate effect on pain, while the effects of the glucose-insulin combination become more apparent at a later stage. When the two agents are combined there is no summation of the effect produced by each one individually. Itch is not affected by this glucose-insulin combination. It is suggested that the role of histamine in pain production is via the potassium releasing process. Evidence is considered to indicate that the major effect of a noxious stimulus is not the direct effect on the pain receptor but indirect due to the tissue reaction.

Submitted on August 26, 1958
Transcapillary exchange rates in acute and intermittent hyperthermia
Authors: Agersborg H. P. K. , Barlow George , Overman R. R.
Published: December 2017

The effects of severe, acute and mild, intermittent hyperthermia on the transcapillary exchange rates of Na24 and of K42 have been studied in dogs. Measurements were made before and after a single exposure to a rectal temperature of 42.5℃ for 1 hour, before and after a single exposure to a rectal temperature of 41.5℃ and before and after exposure to the seventh daily rectal temperature elevation to 41.5℃. The sodium exchange rate was seen to be altered in every instance in which a post-hyperthermic measurement was obtained. A measured change in the potassium exchange rate was found to exist only in the animals which had been exposed to daily bouts of intermittent hyperthermia for 7 days.

Submitted on February 10, 1959
Calcium-45 binding by human prealbumin
Authors: Johnson Philip C. , Smith William O , Wulff Beulah
Published: December 2017

Calcium-45 binding by human albumin and prealbumin has been studied. Protein separation was performed by continuous paper electrophoresis. Calcium-45 was added to the fractions and the mixture incubated at 37℃ for 24 hours. Unbound calcium-45 was removed by dialysis against tap water for 16 hours, the pH of the fractions remained between 8.6–9.1 at all times. Aliquots of the fractions were then counted with a micromil gas flow counter. The greatest specific activity was found in several tubes preceding the albumin, i.e. with faster electrophoretic mobility than classical albumin. The calcium-binding ability of this fraction, which has been previously called ‘prealbumin,’ exceeded that of classical albumin by sixfold.

Submitted on December 1, 1958
Density, fat, water and solids in freshly isolated tissues
Authors: Allen T. H. , Krzywicki H. J. , Roberts J. E.
Published: December 2017

Once the initial density, D1, is noted, a single piece of freshly isolated mammalian tissue is analyzed for water and fat. Knowing the densities of water and fat, the tissue's fat-free density, D2, and the dry, fat-free density, D3, can be computed. Among the various types of soft tissues, since D3 is similar, a simple relationship is shown to exist between the fat-free water content and the corresponding density. The biological extremes in a water:fat:protein system thus operate in such a way that the quantity of fat can be predicted from an equation containing three variables, i.e. the initial weight and density of a tissue and its quantity of water. This is of interest in human body composition and also to those who desire to make a sequence of determinations on a single piece of tissue without having to submit a portion thereof to direct analysis of fat, e.g. to express tissue electrolytes and water content on the fat-free basis.

Submitted on June 15, 1959
Effect of food deprivation on treadmill running in dogs
Authors: Young D. R.
Published: December 2017

Effect of food deprivation on endurance capacity was studied in dogs under the following conditions: a) 3 and 5 days of fasting with daily high levels of energy expenditure and b) 15 days of fasting with low daily levels of energy expenditure. Relative maximum performance, i.e. endurance capacity under conditions wherein work dehydration is a limiting factor, is unaffected by 10–15% body-weight loss and hypoglycemia induced by acute food deprivation. Even with weight loss up to 22%, capacity for daily moderate levels of work is well maintained. Absolute maximum performance (water provided exhaustive treadmill running) improves with 5 days of fasting. Associated with 74% increase in endurance capacity, there is an increased mobilization of body tissue for fuel for the working muscles and a large increase in the post-exercise blood glucose concentration. The dog is resistant to starvation ketosis. In animals tested for absolute performance capacity, the average cumulative calorie deficit, including the exhaustive running trial, was 7500 Calories; yet there was no significant change in the level of blood acetone. It is concluded that absolute performance in the dog increases with 5 days of food deprivation; this response is mediated by a unique permissive effect of such treatment particularly on ability to mobilize body energy reserves.

Submitted on April 17, 1959
Hemolysis caused by pumps in extracorporeal circulation (in vitro evaluation of pumps)
Authors: Cahill John J. , Kolff Willem J.
Published: December 2017

To test in vitro the hemolytic properties of pumps used in extracorporeal circulation, a system was made of polyvinyl chloride tubing. Hemolysis was expressed as the rate of accumulation of free hemoglobin in the plasma determined colorphotometrically. Human blood was recirculated with a single pump in the system. Several pumps—the Sigmamotor, the Leonards occlusive roller, the Hercik nonocclusive roller, the MacNeill-Collins and three modifications of the Dale-Schuster were tested under similar conditions. Some pumps in general clinical use produced as much as 19 mg/100 ml of free hemoglobin/hr. A modified Dale-Schuster pump and a Clowes membrane oxygenator also were tested in the system recirculating 800 ml of blood. The hourly production of free hemoglobin was only 3.2 mg/100 ml/hr. The concentration of free hemoglobin was kept constant by exchange transfusion with a modified Dale-Schuster pump and Clowes membrane oxygenator in the system. A formula used to calculate the required amount of blood to be exchanged is presented.

Submitted on May 11, 1959
Ulnar nerve conduction velocity and H-reflex in infants and children
Authors: Thomas Juergen E. , Lambert Edward H.
Published: December 2017

Measurements of conduction velocity of the motor fibers of the ulnar nerve in the segment between the upper part of the arm and the wrist were made in 6 premature infants, 42 full-term newborn infants and 98 children up through the age of 14 years. In premature infants, 21 – 40 days before full term, values ranged from 18 to 22 meters per second with a mean of 21. Full-term newborn infants had velocities that ranged from 21 to 33 m.p.s., with a mean of 28. The values in the newborn were about one-half those of normal young adults, which range from 47 to 73 m.p.s. (mean, 60). By the age of 3 years almost all values were in the lower part of the adult range and, at 5 years, the velocities were not significantly different from those of the adult. These observations are in harmony with information about the diameter of nerve fibers during growth in man. The H-reflex could be elicited by stimulation of the ulnar nerve in almost every newborn infant. By the age of 1 year and thereafter it could rarely be elicited. Between the elbow and wrist, afferent fibers subserving this reflex conducted with a mean velocity of 30 m.p.s. Data on the action potential of the hypothenar muscles, residual latency of conduction in the ulnar nerve, latency of the H-reflex and conduction in the peroneal nerve in infants and children are compared with those on adults.

Submitted on July 15, 1959
Serum lipoprotein statistics in populations and individuals
Authors: Tamplin Arthur R. , Tandy Robert K.
Published: December 2017

Age and sex trends in individual and population statistics of the low density serum lipoproteins are presented and discussed. The data disclose a lack of conformity between populations which reasonably could be considered comparable random population samples. The data also indicate a metabolic independence of the sf 0 – 20 and the sf 20 – 400 lipoprotein classes and the suggestion is introduced that this is due to a metabolic independence of cholesterol and triglycerides.

Submitted on April 13, 1959
Effects of a short period of training of varying severity on some measurements of physical fitness
Authors: Durnin J. V. G. A. , Brockway J. M. , Whitcher H. W.
Published: December 2017

The experiment attempted to measure whether there was an improvement in physical fitness through varying degrees of exercise which had a duration of only 10 days. Forty-four untrained young men acted as subjects. They were divided into four groups; one group acted as controls and did only a minimum of exercise, while the men in the other three groups walked 10 km, 20 km and 30 km daily, respectively. ‘Fitness’ was assessed by measurements of pulmonary ventilation, oxygen extraction, oxygen consumption and heart rate during a standardized physical test on the treadmill. Recovery heart rate was also measured. The test was done before, during and after the period of training. The use of a submaximal exercise test and the significance of some cardiorespiratory measurements is discussed. The group of men walking 20 km daily showed the most marked improvement in ‘fitness,’ with a significant lowering of pulmonary ventilation, oxygen consumption and heart rate during the test.

Submitted on May 8, 1959
Hematological changes during muscular activity and recovery
Authors: De Lanne R. , Barnes J. R. , Brouha L.
Published: December 2017

Hematological changes were studied in men and women during exercise and recovery under three environmental conditions. An erythrocytosis due to hemoconcentration was observed which was not followed by hemodilution and was not accompanied by the destruction or generation of red cells. Hemoconcentration was influenced by exercise, but not by thermal stress, in spite of greater water losses in warm environments. Sex differences at rest were found for red and white cells, but the pattern of the reactions to exercise was similar for both sexes. Leucocytosis resulted from exercise and heat exposure, with a greater effect of exercise in the females. This is due to increased capillary circulation, hemoconcentration and lymphatic pressure, but not to the stimulation of leucopoietic centers. Changes in the systemic circulation followed by an increase of lymph flow explain the lymphocytosis. Granulocytosis occurs later, persists longer, and may be related to the concentration of circulating corticosteroid hormones.

Submitted on August 24, 1959
Pulmonary resistance and compliance with concurrent radioactive sulfur distribution in dogs breathing S35O2
Authors: Balchum Oscar J. , Dybicki Jerzy , Meneely George R.
Published: December 2017

Ten dogs breathed S35O2 via a tracheal cannula in concentrations ranging from 1.8 to 148 p p.m. There was a decrease in the compliance of the lungs and thorax after 10–15 minutes of inhalation, and an immediate and marked increase in the nonelastic resistance to breathing. S35 was found to be highest in concentration in the trachea, lungs, and hilar lymph nodes, and next highest in the kidneys and esophagus. A relatively uniform and low concentration was noted in other tissues, such as the heart muscle, liver, spleen and striated muscle. S35O2 when inhaled was absorbed quickly, distributed widely to many tissues and readily gained access to many tissues, including the brain.

Submitted on April 28, 1959
A method for continuous recording in vivo of blood oxygen tension
Authors: Kreuzer F. , Harris E. D. , Nessler C. G.
Published: December 2017

A catheter-type Po2 electrode has been developed which permits the polarographic continuous recording of the blood oxygen tension in vivo. The electrodes have the size of ordinary cardiac catheters and yield continuous Po2 tracings in the animal over several hours, with a standard deviation of less than 3%. Model experiments assessed the dependency of the polarographic readings on temperature and showed that static pressure was without effect, but pulsatile pressure caused mechanical deflections depending on the rate of pressure change, and the readings became constant with linear velocities of more than 8–10 cm/sec. In experiments with anesthetized dogs, the readings were calibrated on arterial blood samples analyzed in an in vitro polarograph. With changing inspiratory o2 concentrations, the time for reaching a new equilibrium was found to be 3–4 minutes. The course of the alveolar-arterial o2 gradient was studied over the whole range of inspiratory o2 concentrations. The value of this gradient in the higher o2 ranges permitted the estimation of venous admixture in the anesthetized dog; the average was 5.5% of the cardiac output.

Submitted on February 20, 1959
Determination of oxygenated, mixed venous blood CO2 tension by a breath-holding method
Authors: Knowles John H. , Newman William , Fenn Wallace O.
Published: December 2017

At the end of a normal expiration the subject inhaled a given volume of gas mixtures containing different concentrations of CO2 in O2 from 5 to 17%. These were held in the lung for 3 and then again for 12 seconds and were then expired and analyzed. Analyses were made with an infrared analyzer and times were obtained from the graphical record. If the rate of change of CO2 tension is plotted against the mean CO2 tension a straight line results which passes through zero rate at the tension which equals the tension of CO2 in the mixed oxygenated venous blood. From the slope of this straight line it is possible to calculate the cardiac output if the lung volume and slope of the CO2 dissociation curve of the blood are known. Data are presented from 37 experiments on 10 subjects. The method is believed to be theoretically sound but has not been validated as a practical clinical method. Occasional erratic points were obtained, especially in untrained subjects. The standard error of the mean value for venous CO2 tension was 1.9 mm Hg.

Submitted on July 13, 1959
Effect of sleep deprivation on plasma 17-hydroxycorticosteroids
Authors: Murawski Benjamin J. , Crabbé Jean
Published: December 2017

Paid volunteers, 18 male college students, were deprived of sleep for one night on two separate occasions when alone. On a third occasion they were asked to stay up all night in groups of four. Plasma concentrations of 17-hydroxycorticosteroids at 8:00 a.m. following the nights without sleep were 4–5 μg lower than control values (significant at .01 level). The noon values after sleep deprivation in a solitary setting were not significantly different from the corresponding control values. When subjects stayed up with three other people, the noon values tended to be higher. Urinary 17-hydroxycorticosteroid levels showed a decrease following the nights without sleep, but this decrease did not reach statistical significance (between the .10–.05 level).

Submitted on May 21, 1959
Cardiovascular adjustments in dogs during continuous pressure breathing
Authors: Lenfant Claude , Howell Barbara J.
Published: December 2017

Pressure changes in the pulmonary artery and vein, thoracic vena cava, aorta and intrapleural space as well as the cardiac output were measured in anesthetized dogs subjected to continuous airway pressures varying between -25 to +25 cm H2O. Pulmonary and systemic resistances were calculated. During positive airway pressures the pulmonary artery, vein and vena cava pressures approximately paralleled changes in intrapleural pressures. Cardiac output and aorta pressures decreased; systemic and pulmonary flow resistances markedly increased. During negative airway pressures the pulmonary vessels and vena cava pressures decreased but no longer paralleled the changes in intrapleural pressures. It is assumed that these vessels reached their limit of distensibility. While aortic pressures decreased, cardiac output, systemic and pulmonary resistances remained essentially unchanged.

Submitted on January 14, 1960
Measurement of hepatic blood flow in the unanesthetized dog by a modified bromsulphalein method
Authors: Shoemaker William C.
Published: December 2017

Possible errors of the bromsulphalein method for estimation of hepatic blood flow are enumerated and an analytic method which takes into account the amount of hemolysis present in the samples is described. Improved analytical accuracy allows flow measurements to be carried out at lower bromsulphalein levels, which theoretically allow less extrahepatic bromsulphalein loss and provide larger gradients relative to the circulating level. A preparation for the study of hepatic blood flow and regional hepatic metabolism in the chronic unanesthetized dog is described. Modifications of the bromsulphalein method are proposed for use in this experimental preparation; these modifications include an attempt to obviate the problems of the retrograde hepatic vein catheter technique and a direct measurement of the portal-hepatic venous bromsulphalein concentration gradient. Comparison of hepatic blood flow measurements by the modified bromsulphalein method with direct measurements of flow in the in situ perfused liver have shown comparable results.

Submitted on September 18, 1959