bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Blood in the Arousing Hibernator
Authors: Johansen Kjell 
Published: December 2008

AbstractThe distribution of circulating blood has been studied in the arousing hibernator following the method of fractional distribution of radioactive indicators (Sapirstein 1958). The results indicate a conspicuous differential vasoconstriction of the posterior part of the animal during the most active phase of arousal. The blood flow to skeletal muscle in the front of the arousing animals is more than 16 times greater than in the awake non‐hibernating animals. The perfusion rate to the myocardium is twice as large in the arousing animal. Likewise the lungs, diaphragm, and brown fat show a substantial increase in blood flow. Blood flow to gastrointestinal tissues is greatly reduced in the arousing animals, whereas flow to the skin, liver and thyroid shows insignificant differences.
Physiological Adjustments to Prolonged Diving in the American Alligator Alligator mississippiensis
Authors: Andersen Harald T. 
Published: December 2008

Conspicuous physiological adjustments to experimental submersion have been observed in the natural divers among the birds and the mammals. In order to obtain further information on the phenomena associated with water immersion, and to explore these characteristics in other diving vertebrates, experiments have been carried out on the American alligator, Alligator mississippiensis. The heart rate was found to slow down during diving. The pressure induced in the large arteries by ventricular systole diminished only gradually during diastole, probably due to an increased peripheral resistance resulting from a marked vasoconstriction in certain vascular beds. This thesis was supported by the fact that lactic acid formed in the muscles during diving did not appear in the blood until after emersion, suggesting that the blood flow through the muscles is greatly reduced while the animals dive. The alligator may recover easily from a submergence lasting until the oxygen stores are almost completely depleted. These results indicate that the “diving reflexes” occur in a wide variety of vertebrate divers belonging to different phylogenetic groups. They also support the following conclusions:

The circulatory adjustments, by shutting off the perfusion to certain vascular beds, enable the alligator to make the limited oxygen stores last throughout prolonged periods of submersion.
The animal remains in a state of useful consciousness until the oxygen stores are almost exhausted. This serves to extend the safety 4 margin for prolonged diving and ensure a complete utilization of the oxygen available.
Restoration of Vasoconstrictor Effects in Reserpinized Cats1
Authors: Rosell Sune , Sedvall Goran 
Published: December 2008

Reserpine completely abolishes the effects of vasoconstrictor nerve stimulation (Burn and Rand 1958, Rosell and Rosen 1961). Dopa, dopamine, noradrenaline and adrenaline infused intra‐arterially 20–24 hours after the administration of reserpine partially restored the responses to stimulation of the sympathetic chain. The responsiveness persisted for at least one hour after termination of dopa, dopamine and noradrenaline infusion. With adrenaline, however, vasoconstrictor responses to sympathetic chain stimulation persisted for only a short period after termination of the infusion. The threshold dose for dopa was 2 mg, for dopamine and noradrenaline 25 μg, and for adrenaline 100 μg.The data are considered to support the hypothesis of Burn and Rand (1960) that the adrenergic nerve terminals or adjacent tissue in reserpinized animals have the ability to store infused dopamine and noradrenaline. Adrenaline seems to be stored to a much lesser extent. Dopamine is presumably converted to noradrenaline, which is then released when the sympathetic chain is stimulated. The weak restoration of vasoconstrictor responses following infusion of dopa is of interest. The degree of restoration of the vasoconstrictor effects following infusion of noradrenaline is presumably related to the time elapsed between the administration of reserpine and the infusion.
Electrical Signs of the Relation between Caudate Nucleus and Cerebral Cortex in Cats1
Authors: Laursen Arne Mosfeldt 
Published: December 2008

AbstractCortico‐caudate and caudato‐cortical relationships were explored in the cat using electrical stimuli and recording with gross and micro‐electrodes. The difference in method from previous studies consisted iii the use of a 14‐lead multilead electrode.
Cardiac Inotropic and Skeletal Muscle Vasomotor Responses to Adrenaline and Noradrenaline, Threshold Doses on Intravenous Infusion
Authors: Rosén Anders 
Published: December 2008

AbstractIn cats under chloralose and urethane anesthesia, the mean threshold dose with standard deviation of intravenously infused adrenaline for a cardiac inotropic response was found to be 0.26 ± 0.12 μg/kg/min. and for a muscle vasodilator response 0.44 ± 0.20 μg/kg/min. The mean threshold dose of noradrenaline for an inotropic response amounted to 0.37 ± 0.14 μg/kg/min. and for a muscle vasoconstrictor response to 1.17 ± 0.45 μg/kg/min. The necessity of caution in estimating the differences in the threshold doses between inotropic and vasomotor responses is emphasized.
So‐called Free Erythrocyte Protoporphyrin and its Possible Role in Hemoglobin Formation
Authors: Eriksen Leif 
Published: December 2008

AbstractThe relations of so‐called free erythrocyte protoporphyrin to the number of reticulocytes in the blood of rabbits made anemic by daily injections of 25 mg phenylhydrazine for 5 days, has been studied. The heme forming capacity of the red cells as related to the number of reticulocytes has also been studied. All the data obtained are compatible with the assumption that the amount of free protoporphyrin is not strictly related to the number of the reticulocytes but to the stage of maturation of these cells. The possible role of free erythrocyte protoporphyrin in hemoglobin formation has also been studied, and it has been shown that the main pool of protoporphyrin is not normally utilized for heme formation. It is suggested that free protoporphyrin, although probably a normal intermediate in heme formation, when formed in excess diffuses out into the soluble part of cytoplasm and becomes unavailable for heme formation. The possibility that the true proto‐type intermediate in heme formation differs chemically from protoporphyrin IX is, however, not excluded. It is suggested that excess formed protoporphyrin may in part be the origin of the so‐called early bile pigment fraction found in mammals.
The Formation of Coproporphyrin III and I by Rabbit Reticulocytes Under Hypoxic Conditions in Vitro
Authors: Eriksen Leif , Eriksen Nora , Haavaldsen Synnöve 
Published: December 2008

AbstractIt has been shown that tetrapyrroles having from 4 to 8 carboxylic groups of both the III and I isomer series are formed by rabbit reticulocytes in vitro under hypoxic conditions. The tetrapyrroles of the III series are rapidly converted into protoporphyrin under aerobic conditions, while the tetrapyrroles of the I series are converted into coproporphyrinogen I. The implications of these findings have been discussed and it is suggested that an 8‐carboxylated openchained tetrapyrrolic intermediate of the I series is normally formed by a deaminase, the so‐called porphobilinogenase, and that this tetrapyrrole is condensed spontaneously into uroporphyrinogen I if this condensation is not hindered by a second enzyme, the so‐called isomerase. The possible effect of the latter is discussed and a scheme for the formation of ringformed tetrapyrroles of both the III and I series has been suggested. It is further suggested that the formation of ringformed tetrapyrroles of the I series is due to inhibition or blockage of the isomerase with spontaneous condensation into uroporphyrinogen I of the openchained tetrapyrrole of the I series formed by the deaminase, uroporphyrinogen I being rapidly converted by the decarboxylases present into coproporphyrinogen I. The accumulation of the latter when the atmosphere is changed into air, shows that the enzymes responsible for the conversion of coproporphyrinogen into protoporphyrin are highly specific and can utilize only coproporphyrinogen III and explains why porphyrins having less than 4 carboxylic groups have been found in nature only as isomers of the III series.
Different RNA Fractions during Cell Growth and Synchronous Division in Mass Cultures of Tetrahymena Pyriformis
Authors: Christensson Erik 
Published: December 2008

AbstractThe cellular divisions in mass cultures of the ciliate Tetrahymena pyriformis GL were synchronized through heat treatment. At all stages of the cell cycle were found two metabolically and chemically distinct classes of RNA fractionated by phenol. The fraction left behind in the phenol was poorer in guanylic acid and incorporated radioactive phosphorus more rapidly than the other that had been released in the phenol aqueous phase. The RNA fractions left behind in phenol decreased during heat treatment but showed a rapid increase prior to division. The RNA of the aqueous phase, on the other hand, rose almost proportionally to the cell size up to division. The RNA fraction released in the aqueous phase was chromatographed on Ecteola cellulose ion‐exhange columns.
Distribution of Extra‐ and Intrathoracic Pressure Variations in Rabbits Exposed to Air Shock Waves
Authors: Clemedson Carl‐Johan , Jönsson Arne 
Published: December 2008

AbstractRabbits were exposed directly, and excised rabbit and calf lungs after mounting in a pulse guide system, to high explosive air shock waves in a detonation chamber. The incident shock wave as well as the resulting pressure wave patterns were recorded by means of piezoelectric pressure transducers, simultaneously in the lungs, in the heart ventricles, or in the intercostal musculature of both sides of the thorax in the in vivo experiments, and immediately before and after the passage of the lung in the experiments in the pulse guide system. The velocity of propagation of the main part of a pressure pulse in the lung generally was found to be of the order of 15 to 30 m/sec. The velocity of the same type of pulse through the whole chest of some guinea pigs exposed in the pulse guide was of the same order of magnitude, indicating that the main part of the pulse in this case was transmitted through the lungs and not in the thoracic wall structures, which have a much higher transmission velocity. The very low intrathoracic transmission velocity indicates that in an animal, which is exposed freely to and engulfed by the shock wave, the main resulting pressure wave is not propagated through the thorax from one lung to the other. In this case a very complex relationship exists between the temporal and spatial distribution of the resulting extra‐ and intrathoracic forces.
The Effects of D‐ and L‐lactate and Osmotic Diuretics on Uric Acid Clearance in the Rabbit
Authors: Möller Jesper V. 
Published: December 2008

AbstractIt has repeatedly been found that ingestion of lactate diminishes the renal excretion of urate in man. The effect of intravenous injection of D‐ and L‐lactate on urate excretion in the rabbit was investigated, standard clearance technique being employed. At excretory rates of 0.1–0.4 mg/min of lactate no change in urate excretion could be detected. A reduction in urate clearance was observed when the mean urinary excretion of D‐ or L‐lactate was 1.1–3.1 mg/min, and this is attributed to inhibition of tubular secretion of urate. In two instances, marked uricosuria occurred when the rate of lactate excretion was raised to 7.9 and 10.0 mg/min. This may be attributed to the osmotic effect of lactate, since osmotic diuresis induced by mannitol and sulfate infusion were similarly accompanied by so great an increase in the urate excretion that the urate clearance exceeded the creatinine clearance. The results suggest that both active reabsorption and secretion of urate are operating in the rabbit.
Comparison of Ascending Spinal Tracts Activated by Group I Muscle Afferents in the Phalanger, Rabbit, and Gat
Authors: Magni Franco , Oscarsson Olov 
Published: December 2008

AbstractThe discharges evoked in ipsilateral and contralateral spinal tracts by a volley in group I muscle afferents in the phalanger and rabbit are similar to the previously investigated, corresponding discharges in the cat. In all three species, the responsible ipsilateral and contralateral tracts are influenced from group II and III muscle afferents and cutaneous afferents according to similar patterns. It is concluded that these tracts represent subdivisions of the dorsal and ventral spino‐cere‐bellar tracts respectively.
Principal Organization of Coarse‐Fibred Ascending Spinal Tracts in Phalanger, Rabbit, and Gat
Authors: Magni Franco , Oscarsson Olov 
Published: December 2008

AbstractTracts ascending in the dorsolateral funiculus have a different organization from tracts ascending in the ventral quadrant of the cord as disclosed by experiments in phalanger and rabbit and by previous observations in cat. Tracts in the dorsolateral funiculus are mono‐ and polysynaptically activated only from ipsilateral nerves. Tracts in the ventral quadrant are monosynaptically activated only from contralateral nerves and polysynaptically activated both from ipsilateral and contralateral nerves. The difference in organization of the two groups of ascending tracts is considered to represent a principal pattern of organization in the mammalian cord and a theory is given to account for it.
Effects of Posture on Alveolar‐Arterial CO2 and O2 Differences and on Alveolar Dead Space in Man
Authors: Bjurstedt H. , Hesser C. M. , Liljestrand G. , Matell G. 
Published: December 2008

AbstractThe increase in ventilation and lowering of the end‐tidal Pco2 after changing from the supine to the standing position were observed to be associated with a significant rise in the arterial to end‐tidal CO2 tension difference (average +2.1 mm Hg) in addition to an increased effective alveolar to arterial O2 tension difference (+ 4.8 mm Hg). All dead spaces increased, the alveolar dead space (= the physiological minus the anatomical dead space) on an average by 28 ml. Assuming an unchanged distribution of ventilation this can be expressed as corresponding to 6 per cent of the alveoli being unperfused. A lowering of the alveolar Pco2 during standing is thus in part due to an increased arterial to end‐tidal COa tension difference. The end result is also influenced by a certain metabolic acidosis (average decrease in BHCO3st = 0.6 mM/1), in addition to peripheral retention of CO2. The Eff. VA/VE ratio decreased in all subjects, indicating a decline in the respiratory gas exchange efficiency by an average of 6 per cent. The changes observed may be explained as a consequence of the influence of gravity on the blood flow and its distribution not only in the systemic but also in the pulmonary circulation.
A Method for the Determination of Normetanephrine in Brain
Authors: Carlsson Arvid , Lindqvist Margit 
Published: December 2008

AbstractBrain tissue is extracted with perchloric acid. The extract is neutralized and passed through a Dowex 50 column. Elution is performed by means of a carbonate‐bicarbonate buffer, pH 10. Utilizing the principles of the trihydroxyindole method the normetanephrine of the eluate is converted into a strongly fluorescent compound. Fluorescence is measured in a spectrophotofluorometer. Results are satisfactory with respect to reproducibility, recovery, and specificity.
The Effect of Lowering the Pulse Pressure in the Carotid Arteries on the Cardiac Output in the Cat
Authors: Groom A. C. , Löfving B. M. A. , Rowlands S. , Thomas H. W. 
Published: December 2008

AbstractGroom, A. C, B. M. A. Lofving, S. Rowlands and H. W. Thomas. The effect of lowering the pulse pressure in the carotid arteries on the cardiac output in the cat. Acta physiol. scand. 1962. 54. 116–127. Cardiac output was measured by a radioactive indicator dilution method at normal and reduced carotid pressure in anaesthetized, spontaneously breathing cats. The carotid baroreceptor activity was decreased by partial occlusion of a special screw‐clamp, mounted around the innominate artery, so as to reduce mainly the pulse pressure, while mean carotid blood pressure fell only 10–20 mm Hg. These changes produced a reflex rise in mean systemic pressure of 50–80 mm Hg. – Ten pairs of observations were made in each often animals. In no case did cardiac output increase; it remained essentially unchanged in five of the animals and in the others it fell, while at the same time a reflex bradycardia was seen. Evidence is presented that this fall in cardiac output was brought about by a vagal inhibition of the heart rate, presumably induced by cardiac receptors. After vagotomy or atropine administration this latter group of animals showed no change in cardiac output on reducing the carotid sinus pulse pressure. It is concluded that, under the present experimental conditions, the reflex adjustments elicited by moderate shifts in the baroreceptor influence on the bulbar cardiovascular centres are so balanced as to keep cardiac output essentially unchanged despite changes in the peripheral resistance.
Hypoxemia in Man Induced by Prolonged Acceleration
Authors: Barr P.‐O. 
Published: December 2008

AbstractBarr, P.‐O. Hypoxemia in man induced by prolonged acceleration. Acta physiol. scand. 1962. 54. 128–137. – Changes in the arterial oxygen saturation were recorded in healthy subjects on the human centrifuge by continuous cuvette oximetry before, during and after prolonged exposures to positive acceleration. With the subjects breathing air and wearing an automatically inflated anti‐g suit, an immediate fall in the arterial O, saturation was observed upon exposure to 4.5–5.0 g. After one minute of the first exposure the O2 saturation ranged between 95 and 81 per cent, the arterial pH remaining essentially unchanged. At the same time the respiratory minute volume had increased, indicating gross deterioration in the efficiency of pulmonary function. Repeated exposures caused the arterial O2 saturation to fall at a faster rate and to a lower level with each consecutive run. The rate of resaturation on returning to normal gravity was usually slow, and markedly so after several exposures. The arterial hypoxemia is interpreted as being mainly a shunt effect caused by congestion with collapse of alveoli (“atelectasis”) in dependent regions of the lungs. The potential dangers of acceleration‐induced hypoxemia in high performance flight missions are discussed.
The Influence of Sympathetic Adrenergic Vasoconstrictor Nerves on Transport of Diffusible Solutes from Blood to Tissues in Skeletal Muscle
Authors: Renkin Eugene M. , ROSELL SUNE 
Published: December 2008

AbstractArteriovenous (A‐V) extraction of rubidium ‐86 was continuously recorded in isolated skeletal muscles of dogs and cats perfused with blood at constant flow. In a few experiments, A‐V extraction of oxygen was measured also. The sympathetic trunk, still connected to the muscle, was stimulated electrically under various conditions. Excitation of sympathetic adrenergic vasoconstrictor nerves produced an increase in vascular resistance and a decrease in Rb86 and O2 transport. These effects were graded in relation to stimulus frequency, persistent throughout continued stimulation and large enough to be of importance at low, physiological frequencies. The changes in vascular resistance and blood‐tissue transport are mechanically independent. Both are mediated by preganglionic fibers of similar properties, but it is not possible to tell if the same or different fibers are involved. The reduction in transport is considered to result mainly from restriction of the number of open capillaries, due to closure of precapillary sphincters, with some contribution from a decrease in the uniformity of circulation through those parts of the capillary network remaining open
Functional Organization of the Ventral Spino‐Cerebellar Tract in the Cat. IV. Identification of Units by Antidromic Activation from the Cerebellar Cortex
Authors: Lundberg A. , Oscarsson O. 
Published: December 2008

AbstractFibres of the ventral spino‐cerebellar tract have been identified by antidromic activation from the anterior cerebellar lobe cortex. These neurones received polysynaptic excitation and inhibition from flexor reflex afferents in both contralateral and ipsilateral nerves and some were, in addition, monosynaptically activated from contralateral group I muscle afferents. The conduction velocities of the fibres ranged from 70 to 120 m/sec. Most fibres terminated contralaterally in a longitudinal zone consisting of a medial strip of the intermediate cortex and a lateral strip of the vermal cortex.
Two Ascending Spinal Pathways in the Ventral Part of the Cord
Authors: Lundberg A. , Oscarsson O. 
Published: December 2008

AbstractTwo pathways with axons ascending in the ventral part of the cord have been identified as not belonging to the ventral spinocerebellar tract because the axons could not be antidromically activated from the cerebellar cortex. One pathway ascends to the lower brain stem, is polysynaptically activated from the flexor reflex afferents of a bilateral receptive field, and receives strong excitatory and inhibitory actions from the anterior cerebellar lobe. The other pathway, with unknown Termination, is polysynaptically activated from the flexor reflex afferents of a contralateral receptive field, and is not influenced from the anterior cerebellar lobe.
The Metabolism of 1‐C14‐Palmitic Acid in Rats with Ethionine‐Induced Fatty Livers
Authors: Olivecrona Thomas 
Published: December 2008

AbstractC14‐palmitic acid bound to albumin was injected into normal and ethionine‐treated fasted female rats. Plasma, liver and carcass lipids were isolated and their specific activities determined. The initial halflives of the injected label were 0.61 and 0.92 minutes, the concentrations of plasma FFA 1.0 ± 0.3 and 1.6 ±; 0.4 μeq/ml, and the fluxes of plasma FFA calculated from this data, 9.0 and 9.3 μeq/min in the normal and ethionine‐treated rats respectively. The fraction of the plasma FFA flux taken up by the liver was about the same in the two groups, namely about 30 %. The initial incorporation of label into the liver NFFA was similar. The further metabolism of liver NFFA was slower in the ethionine‐treated group. Differences in liver PLFA metabolism were slight. In the normal rats a flux of approximately 10 % of the injected label through the plasma TGFA pool took place from 10–40 minutes after the injection. In the ethionine‐treated rats this flux was less than 1 %. The concentrations of plasma TGFA and PLFA were also lowered in the ethionine‐treated rats. The oxidation of the injected label was slower in the ethionine‐treated rats than in the normal ones. The accumulation of NFFA in the livers of the ethionine‐treated rats appears at least in part to be due to decreased transport of fatty acids from the liver in the form of plasma TGFA. Other factors may be depressed oxidation of fatty acids in the liver and/or increased liver uptake of fatty acids
The Behaviour of the Cerebral Circulation during Muscular Exercise
Authors: Hedlund Sven , Nylin Gustav , Regnström Olof 
Published: December 2008

AbstractThe behaviour of the cerebral circulation during muscular exercise has been studied in 4 healthy males by injecting labelled erythrocytes into the internal carotid arteries and sampling from the internal jugular bulbs. There seems to be little if any increase in the cerebral blood flow and the circulation time through the brain, even though there was a considerable rise in the cardiac output and the arterial blood pressure. The cerebral blood volume was apparently constant