bluuebunny/crossref_metadata_2025 huggingface dataset:
Fetal cardiovascular and breathing responses to an adenosine A2a receptor agonist in sheep
Authors: Koos Brian J. , Chau Andrew
Published: December 2017

CGS-21680 (CGS), a highly selective adenosine A2a receptor agonist, may excite the fetal carotid bodies. This study was designed to determine 1) whether CGS stimulates fetal breathing and 2) whether sinoaortic denervation abolishes CGS-induced tachycardia. In eight intact fetuses (>0.8 term), intra-arterial CGS infusion (6 μg ⋅ min−1 ⋅ kg estimated fetal wt−1) increased mean arterial [Formula: see text] by 3–7 Torr, reduced fetal arterial[Formula: see text] by 2–5 Torr, and produced a mild metabolic acidemia. Heart rate increased from 154 ± 7 (control) to 249 ± 12 beats/min, but mean arterial pressure was not significantly affected. CGS initially increased the frequency, amplitude, and incidence of fetal breathing, but this hyperpnea was followed by prolonged respiratory depression that was not reversed with blockade of adenosine A1 receptors. Denervation of both carotid bodies together with interruption of the vagi abolished the hyperpnea without altering the respiratory depression or the maximum rise in heart rate. We conclude that CGS induces 1) tachycardia by a mechanism independent of the peripheral arterial chemoreceptors, 2) hyperpnea by stimulating peripheral adenosine A2areceptors, and 3) respiratory depression by activating central A2a receptors.
Prejunctional M1 facilitory and M2 inhibitory muscarinic receptors mediate rat bladder contractility
Authors: Braverman Alan S. , Kohn Ira J. , Luthin Gary R. , Ruggieri Michael R.
Published: December 2017

Subtype-selective muscarinic antagonists effects on carbachol-induced and electric field-stimulated contractility of rat bladder were compared in vitro. Schild plot analysis of cumulative carbachol dose-response curves in the presence of antagonists was consistent with M3-mediated bladder contractions. However, nerve-evoked contractions were inhibited 15% at 30 Hz ( P < 0.01) by 10 nM pirenzepine (M1-selective antagonist), whereas 10 nM methoctramine (M2-selective antagonist) increased these contractions by 17% at 30 Hz ( P < 0.01). Identical doses had no effect on carbachol-induced contractions, indicating prejunctional M1 facilitory and M2 inhibitory receptors. m1 Receptors could not be identified by subtype-selective antibodies, nor could the m1 transcript be identified by Northern hybridization. However, m1, m2, m3, and m4 transcripts were identified in rat bladder using the reverse transcriptase-polymerase chain reaction, providing support for the existence of the m1 subtype. In conclusion, strong evidence is provided for the existence of prejunctional M1 facilitory and M2 inhibitory and postjunctional M3 receptors modulating contractility in the rat urinary bladder.
Integration and saturation within the circadian photic entrainment pathway of hamsters
Authors: Nelson Dwight E. , Takahashi Joseph S.
Published: December 2017

The sensitivity of the visual pathway that subserves circadian entrainment was measured in hamsters after prior stimulation and using trains of multiple pulses. Immediately after subsaturating stimulation in the late subjective night, there was a significant decrease in responsiveness that persisted for at least 1 h. The reduced responsiveness was not due to light adaptation (shifting of the stimulus-response curve) but rather to response saturation, which appeared to reduce the sensitivity to subsequent stimulation and limit the maximum response of the pacemaker. The system, therefore, integrates the total number of photons delivered in two light stimuli separated in time by up to 1 h. The responsiveness was also measured using stimulus trains containing 10–1,000 individual pulses of equal irradiance and equal total photons. Results suggest that this pathway is responsive to the total photons delivered in all of the stimuli and is not responsive to light onsets or offsets associated with individual stimuli. These data outline several fundamental characteristics of phase shifting for the circadian photic entrainment pathway in hamsters. Knowledge of these characteristics is important for designing and interpreting results of future studies to dissect the cellular and molecular nature of the mammalian circadian clock and for understanding how visual information affects the cellular clock during entrainment.
Suppression of food intake, body weight, and body fat by jejunal fatty acid infusions
Authors: Cox James E. , Tyler William J. , Randich Alan , Kelm Gary R. , Bharaj Satinder S. , Jandacek Ronald J. , Meller Stephen T.
Published: December 2017

Three experiments investigated effects of jejunal lipid infusions given on 4 or 21 consecutive days in adult, male Sprague-Dawley rats. In experiment 1, 7-h infusions of linoleic or oleic acid (0.2 ml/h for 7 h; total load = 11.5 kcal) on 4 consecutive days reduced total intake (ad libitum consumption of the liquid diet Boost, Mead Johnson, plus load) by ∼15% and decreased weight gain compared with 4-day tests with saline administration. In experiment 2, linoleic acid at 0.1 ml/h for 7 h (5.7 kcal) was ineffective, whereas the same load delivered in 3.5 h produced effects similar in magnitude to those in the first experiment. In experiment 3, jejunal infusions of linoleic acid (0.2 ml/h for 7 h) on 21 consecutive days reduced mean total intake by 16%, body weight by 10%, and carcass fat by 48% compared with controls receiving saline. The net decrease in caloric intake may reflect the combined activation of pre- and postabsorptive mechanisms, and it suggests a possible treatment for obesity.
Feeding-entrained circadian rhythms are attenuated by lesions of the parabrachial region in rats
Authors: Davidson Alec J. , Cappendijk Susan L. T. , Stephan Friedrich K.
Published: December 2017

Rats anticipate daily restricted meals with increased approaches to a feeder and an increase in core body temperature. Food anticipatory activity (FAA) is thought to be under the control of a feeding-entrained circadian oscillator. Although numerous forebrain lesions have failed to permanently abolish FAA, the hindbrain has not been investigated. The parabrachial nuclei (PBN) integrate information from visceral and gustatory afferents. This region is also innervated by neurons in the area postrema that have access to the peripheral circulation. Therefore, it is possible that this region plays a role in triggering FAA. In two experiments, a total of 19 rats were given ibotenic acid or electrolytic lesions targeted at the PBN. The PBN-lesioned animals showed a marked attenuation in anticipatory approaches to the food bin relative to sham-operated controls. Some animals did not anticipate the meal at all. In addition, the expected increase in core body temperature was severely attenuated in the PBN-lesioned animals compared with controls. The most likely interpretation of these data is that the PBN serve as a relay for information about the zeitgeber (food in the gut) or as a clock output pathway, but not as the site of the feeding-entrained circadian oscillator.
Intrapericardiac injections of algogenic chemicals excite primate C1-C2 spinothalamic tract neurons
Authors: Chandler Margaret J. , Zhang Jianhua , Qin Chao , Yuan Yu , Foreman Robert D.
Published: December 2017

Extracellular potentials of 38 C1-C2 spinothalamic tract (STT) neurons in anesthetized monkeys ( Macaca fascicularis) were examined for responses to intrapericardiac injections of an algogenic chemical mixture (adenosine, 10−3 M; bradykinin, prostaglandin E2, serotonin, histamine, each 10−5 M). Chemical stimulation of cardiac/pericardiac receptors increased activity of 21 cells, decreased activity of 5 cells, and did not change activity of 12 cells. Cells excited by chemical stimuli received input from noxious mechanical stimulation of somatic fields; most receptive fields included the neck, inferior jaw, or head areas. Nerve ablations in 11 cells excited by intrapericardiac chemicals showed that cardiac input activated by algogenic chemicals traveled primarily in vagal afferent fibers to C1-C2 segments; phrenic or cardiopulmonary sympathetic inputs were predominant in 2 of 11 cells. These results supported the concept that activation of cardiac vagal afferents might lead to the production of referred pain sensation in somatic fields innervated from high cervical segments.
[Ca2+]i in rat afferent arteriole during constriction measured with confocal fluorescence microscopy
Authors: Yip K. P. , Marsh D. J.
Published: December 2017

Using confocal fluorescence microscopy, we followed the time course of intracellular calcium concentration ([Ca2+]i) in vascular smooth muscle cells (VSMC) and endothelial cells (EC) of microperfused afferent arterioles isolated from rat juxtamedullary nephrons. Measurements were made while arterioles were exposed to pharmacological agonists or myogenic stimulation. Luminal addition of acetylcholine triggered an immediate increase of [Ca2+]i in EC and vasodilation. Addition of norepinephrine to the bath solution constricted the vessel and initiated periodic oscillations of [Ca2+]i in VSMC and synchronized vasomotion. Increase of perfusion pressure from 80 to 120 mmHg induced an immediate 9.6 +/- 2.9% (P < 0.05, n = 9) increase of [Ca2+]i in VSMC that was sustained. The arteriole dilated transiently when the perfusion pressure was increased, and persistent vasoconstriction to reduced diameter was observed after 35 s. When nitric oxide (NO) production in the perfused vessel was blocked with nitro-L-arginine methyl ester prior to the pressure step, similar profiles of change in VMSC [Ca2+]i were observed and persistent vasoconstriction began after 28 s. The same pressure step triggered an increase of [Ca2+]i in EC by 11.3 +/- 1.1% (P < 0.05, n = 5). These observations suggest that myogenic constriction of afferent arterioles was associated with an increase of [Ca2+]i in VSMC, and the constriction was delayed by endogenous NO production.
Induction of FGF-7 after kidney damage: a possible paracrine mechanism for tubule repair
Authors: Ichimura T. , Finch P. W. , Zhang G. , Kan M. , Stevens J. L.
Published: December 2017

A member of the fibroblast growth factor (FGF) family, keratinocyte growth factor (FGF-7 has unique specificity for epithelial cells. We investigated the role of FGF-7 in repair of proximal tubular damage caused by S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFEC). In situ hybridization localized FGF-7 to interstitial cells in the medulla and outer stripe of the outer medulla. Interstitial FGF-7 expression increased throughout the kidney 1 day after TFEC treatment. FGFR2 IIIb mRNA was high in the papilla and medulla and also increased after TFEC administration. By in situ hybridization, FGFR2 IIIb was localized to the tubular epithelium, particularly in collecting ducts. Proliferation of collecting duct epithelial cells increased in adult kidney after damage to the proximal tubule. FGFR2 IIIb, but not FGF-7, mRNA was also expressed by rat proximal tubule epithelial (RPTE) cells in vitro, and FGF-7 increased DNA synthesis in RPTE. Thus FGFR2 IIIb and FGF-7 expression is segregated between epithelial and interstitial cells forming a paracrine growth factor loop. These results raise the possibility that a novel paracrine growth loop is activated by chemical damage and regulates epithelial cell growth during tubular repair.
Localization and regulation by vitamin D of calcium transport proteins in rabbit cortical collecting system
Authors: Van Baal J. , Yu A. , Hartog A. , Fransen J. A. , Willems P. H. , Lytton J. , Bindels R. J.
Published: December 2017

The 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3]-induced expression of Na+/Ca2+ exchanger, Ca(2+)-adenosinetriphosphatase (Ca(2+)-ATPase), and calbindin-D28k was investigated in the rabbit distal nephron. Immunocytochemical studies in rabbit kidney sections revealed colocalization of the three Ca2+ transport proteins in the majority of cells in the distal nephron, including connecting tubules and cortical collecting ducts. Subsequently, rabbit connecting and cortical collecting tubule cells were immunodissected and cultured on permeable supports. Immunocytochemical analysis of the cultured cells by confocal microscopy revealed that Na+/Ca2+ exchanger and Ca(2+)-ATPase were present at the basolateral membrane, whereas calbindin-D28k was evenly distributed throughout the cytosol. Concomitant with an increase in Ca2+ transport, 1,25(OH)2D3 increased calbindin-D28k protein and RNA content two- to threefold, as determined by Northern and Western blotting. By contrast, neither Na+/Ca2+ exchanger nor Ca(2+)-ATPase RNA or protein content was noticeably altered. Our findings suggest that 1,25(OH)2D3 stimulation of transcellular Ca2+ transport in primary cultures of rabbit cortical collecting system cells involves an increase in the gene expression of calbindin-D28k but not of Na+/Ca2+ exchanger and Ca(2+)-ATPase.
P2 purinoceptor stimulation attenuates PTH inhibition of phosphate uptake by a G protein-dependent mechanism
Authors: Lederer E. D. , McLeish K. R.
Published: December 2017

Pages F309–F316: E. D. Lederer and K. R. McLeish. ”P2 purinoceptor stimulation attenuates PTH inhibition of phosphate uptake by a G protein-dependent mechanism.“ The American Heart Association of Kentucky should have been acknowledged for their support of E. D. Lederer.
Pattern of N15-excretion in man following administration of N15-labeled glycine
Authors: Wu Hsien , Bishop Charles W.
Published: December 2017

The patterns of N15-excretion, as shown by isotope concentration-time curves for ammonia, hippuric acid and urea, are different in the first few hours after oral and intravenous administration of N15-labeled glycine. After 6–8 hours, the curves are substantially the same. Therefore, data obtained in oral and in intravenous experiments should not be treated indiscriminately from the beginning. The ratio of the isotope concentration of glycine (calculated from that of hippuric acid) to that of ammonia should, on the basis of certain assumptions, theoretically begin with a high value (i.e. 20) and fall eventually to 1 when transamination equilibrium is reached. In an oral experiment the ratio found is 8.5 at 1 hour, 6.1 at 2 hours and 2.6 at 14 hours. It may be concluded that the transfer of NH2 from glycine to the other amino acids is not so rapid, compared with rates of other metabolic reactions of the amino acids, as to justify the assumption of a single pool for all amino acids from the beginning. The implications of this finding with reference to interpretation of N15-excretion data are discussed, and some sample calculations with data in the glycine experiments are given in a subsequent paper.

Submitted on September 15, 1958
Effects of semistarvation and water deprivation on adrenal cortical function and corticosteroid metabolism
Authors: Huseby Robert A. , Reed Fredrick C. , Smith Thomas E.
Published: December 2017

The urinary excretion of 17-KS and 17-OH-CS and the level of circulating unconjugated 17-OH-CS in the plasma were determined in 12 healthy young subjects during a 16-day period of acute undernutrition. In half the group, the intake of water was also significantly restricted during the first 5 1/2 days. The data indicate that although the urinary excretion of steroid metabolites decreased rapidly during the first 6 days of undernutrition and then stabilized at a level approximately half that seen in the control period, the level of circulating unconjugated 17-OH-CS in the plasma was not depressed by this degree of acute undernutrition and protein deprivation. Dehydration increased the level of circulating unconjugated 17-OH-CS, indicating that the pituitary-adrenal axis could respond to ‘stress’ when the diet was calorically inadequate and protein-deficient. These findings have been interpreted as indicating that acute undernutrition and protein deprivation alter the catabolism of adrenal steroids, but that the level of circulating hormonally-active corticosteroids reaching the tissues of the organism is probably adequate.

Submitted on July 28, 1958
Elastic characteristics of isolated segments of human aortas under dynamic conditions
Authors: Cope Freeman W.
Published: December 2017

When isolated segments of human descending thoracic aorta were caused to change their volume rapidly and continuously in sinusoidal fashion with pulse pressures and pulse rates maintained in the physiological range, the resulting pressure-volume curves showed slight but consistent increases in stiffness, compared to pressure-volume curves obtained on the same specimens when inflated stepwise. There was introduced into the pressure measuring system a time lag of sufficient magnitude to eliminate the hysteresis loop. The extent of hysteresis in the aorta was not determined because time lags in the aorta could not be distinguished from time lags in the measuring equipment.

Submitted on September 10, 1958
Fate of radioactive krypton (Kr85) introduced intravenously in man
Authors: Chidsey C. A. , Fritts H. W. , Hardewig A. , Richards D. W. , Cournand A.
Published: December 2017

When a small volume of dissolved Kr85 was rapidly injected into the venous circulation, only about 5% of the injected gas appeared in the systemic arteries. Further, when a similar solution was infused over a 10-minute period, the fraction reaching the systemic arteries was less than 15% of that contained in the pulmonary arterial blood. Because the problem of recirculation was minimized, an infusion of Kr85 was used to measure continually the output of the right ventricle. The values obtained, both at rest and during steady-state exercise, agreed satisfactorily with direct Fick measurements. Although similar comparisons could not be made in the interval when flow was changing, the values measured with the Kr85 method appeared to be of reasonable magnitude.

Submitted on September 2, 1958
Airway resistance measurement during any breathing pattern in man
Authors: Bartlett R. G. , Brubach H. F. , Trimble R. C. , Specht H.
Published: December 2017

A broadly applicable method for the quantitative and continuous measurement of airway resistance in man is described. It permits the simultaneous measurement of air flow (breath velocity) and alveolar pressure during any breathing pattern. Alveolar pressure is calculated from body plethysmograph pressure (plethysmogram) changes coincident with the compression and expansion of lung air during expiration and inspiration, respectively. The plethysmograph interior is maintained at body temperature and complete H2O saturation. This avoids the errors in measurement due to plethysmograph pressure changes produced by temperature and humidity changes in the inspired and expired breath and also obviates the necessity of using only a panting type breathing pattern. Data on three normal subjects at near resting and near maximum breathing efforts are presented and discussed. This improved method, permitting airway resistance measurements during any breathing pattern, should find application in diagnosis and assessment of treatment of pulmonary diseases as well as in the investigation of several basic pulmonary function problems.

Submitted on June 17, 1958
Genesis of human cerebrospinal fluid
Authors: Lloyd B. B. , Taylor K. B.
Published: December 2017

Analysis of two sets of steady-state data on bromide ion in the serum and cerebrospinal fluid of one human subject and of recently published data on the entry of bromide and sodium ions into human cerebrospinal fluid suggests that bromide is secreted out of the bulk of the cerebrospinal fluid, not excluded from it at a source, and that the secretory activity reaches a maximum at high concentrations of bromide ion.

Submitted on August 25, 1958
Hemolysis of PNH erythrocytes in isotonic solutions of choline esters
Authors: Auditore Joseph V. , Hartmann Robert C.
Published: December 2017

When the acetylcholinesterase activity of normal cells suspended in isotonic choline ester solutions is inhibited by the addition of physostigmine, these cells are more sensitive to H+ ions (i.e. hemolyze at a relatively higher pH) than the control cells. Such observations have led to the hypothesis that acetylcholinesterase may control membrane pH. Erythrocytes of paroxysmal nocturnal hemoglobinuria (PNH) have been demonstrated to be markedly deficient in acetylcholinesterase activity. PNH cells were incubated in isotonic solutions of choline esters and hemolysis and pH changes were followed with time. Such enzyme-deficient cells did not hemolyze at a relatively higher pH, as reported in the case of physostigmine-treated normal cells. The results of these experiments provide no concrete evidence that the erythrocyte acetylcholinesterase enzyme plays any role as an enzyme buffer system. As yet, no simple explanation has been found to correlate the acetylcholinesterase deficiency of PNH erythrocytes with their known susceptibility to hemolysis in acidified serum.

Note:

(With the Technical Assistance of Dorris E. Webb)

Submitted on January 19, 1959
Lyophilized glycerol pectate (lot 18) for plasma volume replacement and expansion
Authors: Handford Stanley W.
Published: December 2017

Lyophilized glycerol pectate (lot 18) was tested as a plasma expander in 10 normovolemic and 10 acute oligemic, unanesthetized dogs. In all cases the hemodynamic responses were favorable and no untoward effects of the infusion solutions were noted. No difficulty in dissolution of the lyophilized lot 18 material was encountered. Approximately 20 minutes was required for reconstitution after the addition of the appropriate amount of isotonic saline solution to the lyophilized material. The physicochemical characteristics of lot 18 furnished by the manufacturer are compared with similar measurements made recently on the same lot of material by other investigators.

Note:

(With the Technical Assistance of Y. Gabr, Aram Belekjian and Paul J. Stonestreet)

Submitted on November 20, 1958
Oxygen consumption and body temperature during sleep in cold environments
Authors: Kreider M. B. , Iampietro P. F.
Published: December 2017

Six young soldiers slept at the following ambient temperatures: 25.5° to 26℃ (78–80℉), 15° to 18.5°C (60°–65℉) and -32° to -34.5℃ (-25°--30℉). Rectal (Tr) and skin temperatures were recorded and mean weighted skin temperature (Ts) was calculated at -hour intervals every night; oxygen consumption (Vo2) was measured at 6-minute intervals on occasional nights. During sleep at a ‘comfortable’ temperature (25.5℃) Tr, Ts and Vo2 decreased below the resting levels measured just before retiring. During sleep in cold environments, Tr and Ts dropped to still lower levels with the lowest values recorded at an early hour of the night. Vo2 during sleep in the cold did not differ from values recorded during sleep at 25.5℃. Lowest values measured during sleep in the coldest environment were 35.5°C, 30.5℃ and 78 Cal/m2 for Tr, Ts and body heat debt, respectively. These values may represent the limits of body cooling compatible with substantially continuous sleep in the cold.

Submitted on February 19, 1959
Effects of artificially induced fever on serum proteins, vitamin levels and hematological values in human subjects
Authors: Méndez José , Scrimshaw Nevin S. , Salvadó Carlos , Selva Manuel López
Published: December 2017

Ten male subjects in apparently good health were submitted to artificial hyperpyrexia of 2°–3℃ above their initial orally determined body temperature for 2-hour periods. The pulse rate was markedly increased and the diastolic blood pressure was markedly decreased. Other major changes observed were a highly significant decrease of serum vitamin A levels and a highly significant increase of the white cell count, due primarily to an increase of the neutrophils. An eosinopenic effect observed was believed to be related to the stress of fever treatment. Minor changes were observed in the red cell count and in the serum gamma globulin fraction, which showed a delayed decrease. No changes were observed in carotene, vitamin E, alkaline phosphatase, riboflavin, or ascorbic acid.

Submitted on January 16, 1959
Changes in osmotic pressure and ionic concentrations of plasma during muscular work and recovery
Authors: Lanne R. De , Barnes J. R. , Brouha L.
Published: December 2017

Changes in the plasma ions and osmolality as a result of exercise under several controlled environmental conditions were investigated. The plasma osmolality rises slightly but significantly during exercise largely because of increases in Na+, K+, Ca++, phosphate, lactate and proteinate. These ions are influenced as much by the environmental temperature and humidity as by exercise. When the changes in ion concentration and hence the osmolality of the plasma are small, the total base is better measured by the depression of the freezing point rather than by conductometry.

Submitted on May 11, 1959
Experimental alterations of certain colloidal properties of blood during cardiopulmonary bypass
Authors: Owens Guy , Adams J. E. , McElhannon F. M. , Youngblood R. W.
Published: December 2017

Microscopic examination of brain, kidney and lung tissues from patients whose unexplained deaths occurred shortly following cardiopulmonary bypass procedures have revealed varying degrees of systemic fat embolization. Similar findings have been observed experimentally in animals when cardiopulmonary bypass has been maintained by a stationary screen oxygenator for prolonged periods. These findings were not altered by changes in the heparin level, the utilization of protamine or by the type of anesthetic agent employed. Animals receiving replacement transfusions of blood, which had circulated in the pump-oxygenator for 2 hours, demonstrated large quantities of peripheral fat emboli. However, very few fat emboli were found if the oxygenator was omitted from the circuit.

Submitted on May 28, 1959
Paradoxical effect of an orally ingested histamine analogue on capillaries and arteriovenous anastomoses of the human digit
Authors: Naftchi Nosrat , Mendlowitz Milton , Weinreb Herbert L. , Gitlow Stanley
Published: December 2017

The effect on the circulation of an orally ingested histamine analogue was studied in nine human subjects, and of subcutaneously administered histamine phosphate in four human subjects. In the digit, a paradoxical effect was observed consisting of capillary and venular dilatation and constriction of arteriovenous anastomoses. The latter effect was probably a reflex response to heat loss caused by the generalized dermal capillary dilatation which was the direct effect of the drug.

Submitted on March 18, 1959
Adaptive changes to moderate seasonal heat in human subjects
Authors: Mefferd Roy B.
Published: December 2017

The excretion patterns of 29 members (including children) of 7 south Texas Caucasian families of varying economic status were determined each November (neutral-cool, averaging 68.7°F) and May (warm, averaging 81.6°F) for 3 consecutive years, to determine whether heat-adaptive mechanisms were stimulated by a moderate increase in average temperature as contrasted to intense heat. Four timed overnight samples from each person were analyzed in each period for five electrolytes, five nitrogenous waste products and thirteen amino acids. Excretion rates of most substances were lower in November than in May. Creatinine and the magnesium/calcium ratio were elevated, however, and the urine volume, magnesium, urea, glutamic acid, arginine and the sodium/potassium and uric acid/creatinine ratios did not change significantly. The excretion patterns of the heat-adapted human subjects were strikingly similar to those seen in heat-adapted rats.

Submitted on April 13, 1959
Effects of restraint on rats exposed to high temperature
Authors: Frankel Harry M.
Published: December 2017

Male rats were placed in a cage either 8 in. x 8 in. x 10 in. (free) or 2 in. x 2 in. x 8 in. (restrained) and exposed to ambient temperatures between 40° and 60°C. ‘Restrained’ rats died sooner than ‘free’ animals at all temperatures. There was no significant difference between final rectal temperatures of free and restrained rats at ambient temperatures greater than 40°C; mean for these groups was 44.6°C. At 40°C the final rectal temperature was slightly lower in the restrained group (43.4° vs. 44.6°C). Restraint had no significant effect on the constituents of the blood examined. Serum potassium and specific gravity and blood hematocrits were increased and serum sodium was unchanged in heat-exposed rats compared with controls at 26°C. Serum calcium varied irregularly with exposure temperature.

Submitted on December 23, 1958
Small volume perfusion system of the isolated rat liver
Authors: Burton Stanley D. , St. George Shirley , Ishida Tadashi
Published: December 2017

A perfusion system utilizing 25 ml of heparinized whole blood as a perfusate has been developed to study the metabolism of the isolated rat liver. Changes in the composition of the plasma of the perfusate were studied by circulation of the whole blood for 3 hours in the presence and absence of the liver. The discharge of glucose by the liver is marked by a pronounced initial hyperglycemia, which is countered slightly by red cell glycolysis. Despite continuous carbohydrate metabolism, a fall in sodium and a rise in potassium concentration occurs, ascribable chiefly to alteration of red blood cells. The hepatic glycogen content decreased slightly during perfusion. Urea production and bile flow were well preserved.

Note:

(With the Technical Assistance of Donna Cary and Veronica Mena)

Submitted on June 26, 1959
Tactile discrimination and skin temperature
Authors: Provins K. A. , Morton Rosemary
Published: December 2017

Ten subjects immersed an index finger in water at 0.75°C for 40 minutes. Two-edge threshold discrimination was tested during cooling of the finger and subsequent spontaneous rewarming due to cold vasodilatation. There was a marked deterioration of tactile discrimination at finger skin temperatures below about 8°C, although the curve showing the mean decrease of numbness with increasing skin temperature was displaced relative to the curve showing the mean increase of numbness with decreasing skin temperature. Tactile discrimination was also tested on five subjects at each of six water bath temperatures (2°, 4°, 6°, 8°, 15° and 30°C). At each temperature the finger was immersed for 20 minutes and the finger circulation arrested after the first 5 minutes. There was little impairment of two-edge discrimination after 15–20 minutes immersion of the finger at temperatures of 6°C or higher. At 4°C there was marked impairment, and at 2°C all subjects experienced complete numbness at the test site.

Submitted on May 18, 1959
Tissue carbon dioxide concentrations in rats during acute respiratory acidosis
Authors: Thompson Alan M. , Brown E. B.
Published: December 2017

Tissue carbon dioxide concentrations were measured in rats following exposure of the intact animals to 10% or 30% Co2 in oxygen for time intervals from 5 minutes to 2.5 hours. The rats were sacrificed by decapitation. The average normal Co2 concentrations in skeletal muscle, heart and brain were 13.2, 18.6 and 15.1 mm/kg of wet tissue, respectively. The tissue Co2 increased at about the same rate, relative to normal concentration, in each of the three tissues, the concentration approximately doubling in the first 35 minutes on 30% Co2. The skeletal muscle Co2 concentration on 30% Co2 followed a single exponential curve in which the rate constant was 0.036 min.-1. Tissue Co2 capacity curves and data on the rate of Co2 loss post mortem are presented. The barium-soluble Co2 fraction of Conway and Fearon was found to increase in skeletal muscle from 9.4 to 14.6 mm/kg wet tissue when rats had been on 30% Co2 for 1 hour. Even in control rats this fraction showed a large variability and may have little physiological significance.

Submitted on April 23, 1959
Mechanical properties and dimensions of the major pulmonary arteries
Authors: Patel Dali J. , Schilder Donald P. , Mallos Alexander J.
Published: December 2017

The relationship between instantaneous distending pressure and diameter of the pulmonary artery was studied in 18 living thoracotomized dogs. An electrical caliper with adequate recording characteristics was developed for instantaneous diameter measurement. Control observations were made over a range of pressures induced by rapid, right heart dextran-infusion and were compared with those obtained during norepinephrine administration. Results indicate: a) the pulse contours of the pulmonary artery pressure and diameter are essentially identical, indicating negligible inertance and viscous resistance of the vessel wall, b) the mean change in average radius during a cardiac cycle was ±7.8% ± 2.86 S.D. ± .32 S.E.M. (0.48%/cm H2O pulse pressure) under control conditions, c) the ratio of change in radius to pulse pressure, R/P, showed a significant decrease during norepinephrine administration when compared to control values within the same pressure range (P < .01) and d) the cross-sectional area of the main pulmonary artery exceeded that of the right and left combined.

Note:

(With the Technical Assistance of Alfred G. T. Casper)

Submitted on August 25, 1959
Flicker fusion thresholds in control subjects and identical twins
Authors: Murawski Benjamin J.
Published: December 2017

Flicker fusion thresholds were investigated in 18 unrelated subjects and 5 pairs of identical twins. Analysis of variance of the findings on 18 subjects followed for 5 weeks demonstrated that flicker fusion thresholds were relatively constant for each individual. Individual differences far outweighed the degree of variability in the same individual from one day to the next. An hypothesis of constitutional determinants of the threshold of fusion appeared to be confirmed in the observations on the identical twins.

wSubmitted on July 22, 1959
Secretion from human submaxillary gland after section of the chorda tympani
Authors: Laage-Hellman Jan-Erik , Strömblad B. Charles R.
Published: December 2017

The sensitivity of the human submaxillary gland to Mecholyl was followed after section of the chorda tympani. A supersensitivity of a low degree developed. The low degree was considered due to the fact that the nerve section did not prevent reflex secretion. An unknown efferent parasympathetic pathway for this secretory reflex is postulated.

Submitted on September 21, 1959
Principles of the Bohr integration procedure and their application to measurement of diffusing capacity of the lung for oxygen
Authors: Briehl Robin W. , Fishman Alfred P.
Published: December 2017

This paper deals with the physiological implications of the successive steps which are involved in the determination of the diffusing capacity of the lungs for oxygen. In the course of the presentation, a ‘Bohr integral chart’ is derived and its geometrical and mathematical bases are indicated. The chart is of theoretical interest in elucidating physiological events, such as the rate of increase in the oxyhemoglobin saturation of blood traversing the pulmonary capillary. It also illustrates the principles which are entailed in use of two levels of oxygenation for the estimation of the diffusing capacity of the lungs for oxygen. An enlarged version of the chart has the practical advantage of simplifying the calculation of the diffusing capacity while keeping before the operator the assumptions and potential sources of error.

Submitted on November 23, 1959
Compliance of the respiratory system and its components in health and obesity
Authors: Naimark A. , Cherniack R. M.
Published: December 2017

The compliance of the total respiratory system and its components was studied in 24 normal and 12 obese spontaneously breathing unanesthetized subjects. The mean compliance of the total respiratory system was .119 l/cm H2O in normal individuals, but was .052 l/cm H2O in obese subjects. The difference indicated an increased elastic resistance to distention. The compliance of the lung in obese individuals was not different from that of the normals. The compliance of the chest wall was .224 l/cm H2O in normal subjects and was .077 l/cm H2O in obese individuals. In contrast to normal subjects, total respiratory compliance was markedly reduced by recumbency in obese individuals. This was entirely due to a further increase in the resistance of the chest wall. A significant correlation was demonstrated between vital capacity and total respiratory compliance in normal and obese subjects. It has been estimated that of the increase in the mechanical work of breathing in obesity is due to elastic work done on the chest wall.

Submitted on November 2, 1959
Distribution of blood flow and ventilation-perfusion ratio in the lung, measured with radioactive CO2
Authors: West J. B. , Dollery C. T.
Published: December 2017

Inhaled radioactive CO2 is rapidly taken up by pulmonary blood. By external counting over the chest during breath holding, the clearance rate of radioactive CO2xs from the counting field can be recorded, and is proportional to the regional perfusion. In normal subjects, the clearance rate varied from about 20%/ sec. at the base of the lung to virtually nil at the apex, and the change was approximately linear with distance up the chest. The difference between upper and lower zones was reduced on moderate exercise and eliminated when the subject lay on his back. By relating the counting rate at the end of inspiration to the volume of lung in the counting field, the difference in ventilation between upper and lower zones was measured and found to be small. Variation in ventilation-perfusion ratio was thus determined. Alveolar-arterial O2 gradient expected from this ventilation-perfusion ratio inequality was calculated to be about 4 mm Hg. This suggests that the variation in blood flow between upper and lower parts of the lung in erect man accounts for the whole of the ventilation-perfusion ratio inequality in the normal lung.

Submitted on November 23, 1959
Ballistocardiographic response to hyperthermia
Authors: Moss Arthur J. , Bradley Bruce E.
Published: December 2017

The body temperature of five normal subjects was raised to levels above 100.0°F through the use of a rubberized anti-exposure suit. The induced hyperkinetic cardiovascular state was studied on an ultra-low-frequency force ballistocardiogram. The ejection deflection (HI wave) consistently increased in amplitude and became more vertical during the hyperthermic state. The time duration from the onset of ventricular ejection to the J wave peak generally was shortened. These changes were interpreted in terms of the known cardiovascular response to the hyperkinetic state. Diminished peripheral resistance and its sequelae seemed to play a major role in the ballistocardiographic changes seen with hyperthermia.

Submitted on November 23, 1959
Pain and thermal burns in skin areas previously exposed to ultraviolet radiation
Authors: Stoll Alice M. , Greene Leon C. , Hardy James D.
Published: December 2017

In order to evaluate the relationship of tissue damage to pain sensation in areas of hyperalgesia, the skin of three subjects was irradiated with injurious doses of ultraviolet radiation and then exposed to thermal radiation. Measurements were made of the pain-threshold-lowering effect of the ultraviolet radiation and, following the development of the hyperalgesia, of the lowering of the blister threshold to thermal radiation. Lowering of the pain threshold of 4-7°C was observed, while the lowering of the blister threshold (i.e. the temperature at which blistering was produced) was of the order of 0.5°C. The ultraviolet-irradiated hyperalgesic skin is therefore not more fragile as regards moderately high temperature (50°C) and high temperature burns than is normal undamaged skin. This finding is in keeping with the previously proposed theory that the intensity of pain is a function of the relative reaction rates at the thermal threshold and at skin temperatures above this threshold. Theory predicts, however, that ultraviolet-irradiated skin heated to, and maintained at, relatively low temperatures (40–45°C) will be more easily blistered than will undamaged skin.

Submitted on December 30, 1959
Magnesium metabolism in human beings: studies with Mg28
Authors: Aikawa Jerry K. , Gordon Gerald S. , Rhoades Eloise L.
Published: December 2017

Mg28 was used to explore the kinetics of magnesium distribution in 9 normal individuals and in 16 patients with various diseases. When Mg28 was given in 12–30 mEq of stable magnesium intravenously, plasma disappearance was rapid within the first several hours. In normal subjects a mean of 19.8% of the injected radioactivity was accounted for in the urine within 24 hours. Fecal excretion was negligible, although equilibration of Mg28 in bile occurred within 18 hours. The specific activities of plasma and urine stabilized by the 18th hour, and showed only a gradual decrease thereafter. Exchangeable magnesium contents in normal subjects ranged between 2.6 and 5.3 mEq/kg of body weight—less than 16% of the estimated total body content of magnesium. Mg28 exchanged very slowly with the stable ion in bone, muscle and erythrocytes. The results in patients with diabetes mellitus and hepatic diseases showed no striking differences from those obtained in normal subjects.

Note:

(With the Technical Assistance of Dale R. Harms and Jacqueline Z. Reardon)

Submitted on October 5, 1959
Response to ventilatory obstruction during steady-state exercise
Authors: Tabakin Burton S. , Hanson John S.
Published: December 2017

Five normal male subjects, 27–37 years of age, were studied during steady-state treadmill exercise to observe the effects of varying expiratory airway obstruction on minute volume, oxygen consumption and carbon dioxide elimination. A 5-mm-diameter resistance produced significant depressions in minute volume for the duration of the obstructed period. Carbon dioxide elimination showed significant reductions during the first 6 minutes of breathing against resistance. Oxygen uptake, however, was reduced significantly only during the 1st minute of obstructed breathing, but the reduction was great enough so that, despite subsequent rises in oxygen uptake, an ‘oxygen debt’ had already been incurred for the total period of obstruction. Following removal of the resistance, all these values rebounded to levels above those of the original steady state. The physiological mechanisms possibly effecting the response to obstruction are discussed.

Submitted on February 24, 1959
Proteinuria during the 24-hour period following exercise
Authors: Coye Robert D. , Rosandich Ronald R.
Published: December 2017

The urine of 10 football players, collected for 24 hours following a practice game, was found to contain 2.3–15.2 times as much protein as urine collected following a period of rest. No changes were noted on electrophoresis of the serum proteins. The renal clearance of serum albumin increased more than the clearance of serum globulins following exercise, but in both the control and post-exercise specimens the clearance of globulins and percentage of globulins in the urine usually exceeded these values for albumin. Considerable variation in the excretion of proteins was noted among individual subjects in the control period; as protein excrextion increased following exercise, the protein excretion patterns became more uniform in these subjects. Compared to the previously described exercise proteinuria which occurs immediately following exercise, this second phase is characterized by less intense protein excretion and longer duration.

Submitted on January 6, 1960
Effect of Adrenalin on human plasma Stypven time and plasma thromboplastin time
Authors: Härtel Gottfried
Published: December 2017

Subcutaneous injection of 0.7 mg of Adrenalin was followed by a significant shortening of the plasma Stypven time in 10 healthy male students. There was no effect of Adrenalin administration on plasma thromboplastin time. It is suggested that the effect of Adrenalin on plasma Stypven time is mediated by the release of some lipid material.

Submitted on January 13, 1960
Homeostasis of carbon dioxide during intravenous infusion of carbon dioxide
Authors: Yamamoto William S. , Edwards McIver W.
Published: December 2017

When rats are infused intravenously continuously with blood enriched in an extracorporeal system with 100% CO2, they are found to excrete the infused CO2 quantitatively. The excretion is accomplished by increasing ventilation in proportion to the infusion rate. Neither mean arterial pH nor Pco2 shows a statistically significant change. This constancy of composition is observed at CO2 infusion rates ranging from zero to an amount equal to six times the resting metabolic CO2 production. Similarity of this hyperpnea to the chief characteristics of the hyperpnea of exercise is notable. Increased oxygen uptake during this procedure is about 3.5 ml/l. of ventilation, a reasonable value for the oxygen cost of ventilation. Since, during this process the animal is quiescent and shows no other metabolic changes it is suggested that the effective signal for the regulation of arterial Pco2 is CO2 itself. The ability of the experimental animal to respond successfully to high rates of loading seems to be limited by failure to make appropriate circulatory adjustments. Removing CO2 by equilibrating blood with 100% o2 in the extracorporeal circuit decreases ventilation, but readily leads to an uncontrolled alkalosis.

Submitted on April 13, 1960
Ventilatory response to forward acceleration
Authors: Zechman Fred W. , Cherniack Neil S. , Hyde Alvin S.
Published: December 2017

Two series of experiments dealing with the effect of forward acceleration on respiration in man were performed. In both series of studies the trunk was inclined 12 degrees in the direction of acceleration and a rate of onset of 1 g/sec. was used. In the first series, the effect of 5, 8 and 12 g on respiratory frequency, tidal volume, minute volume and nitrogen elimination was determined. Frequency increased, reaching an average of 39.2 cpm and tidal volumes decreased to an average of 318 cc at 12 g. The volume of nitrogen eliminated during a 30-second period, breathing O2 at 12 g, was essentially unchanged, suggesting that alveolar ventilation did not decrease. In the second series, O2 consumptions were measured before, during and after accelerations of 5, 8, 10, and 12 g. O2 consumptions increased with acceleration and it is presumed that the extra work of breathing may be an important contributing factor.

Submitted on March 2, 1960
Effect of sauna bath on fibrinolysis
Authors: Miettinen Matti
Published: December 2017

The fibrinolytic activity of plasma is significantly increased immediately after a bath in the sauna. Two hours after bathing, and on the next morning, there is no difference in the fibrinolytic activity between sauna groups and control groups.

Submitted on February 1, 1960
Tolerance of Gaspé fishermen to cold water
Authors: LeBlanc Jacques , Hildes J. A. , Héroux O.
Published: December 2017

A group of Gaspé fishermen used to cold water immersion and control subjects from the same vicinity were studied to determine if the fishermen's hands were adapted to cold. With one hand immersed in cold water, the pressor response was greater in the control subjects; the fishermen maintained a higher finger temperature and complained less of pain; heat flow from the fishermen's hands was greater than in the control group; finger numbness as measured by a modification of Mackworth's V-test was variable and not significantly different in the two groups. Skin biopsies showed no difference in skin thickness or cell size but there was a significantly greater number of mast cells in the fishermen's skin. The differences between the fishermen and the control subjects may be related to repeated cold exposure.

Submitted on June 7, 1960
Maximal work of one breathing cycle
Authors: Craig Albert B.
Published: December 2017

The method used enables one to record directly the pressure-volume diagram of a subject while breathing against a high resistance. The average work accomplished during expiration was 69% and, during inspiration, 79% of that which was predicted from the pressures developed against a column of mercury at different lung volumes. When maximal respiratory efforts are assessed, one can expect to incur the same problems of defining maximum as are encountered with other muscles.

Submitted on June 2, 1960