bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stimulation of Sweating by Exercise after Heat Induced“Fatigue” of the Sweating Mechanism
Authors: Ahlman K. , Karvonen M. J. 
Published: December 2008

AbstractWhen wrestlers lose weight before a competition, they often induce sweating in a hot bath until the“fatigue” of the sweating mechanism. It is reported that at this stage exercise may still induce sweating. This claim was tested in experiments on five young males. After three or four exposures of 12 min each to ambient heat in a“sauna” bath which caused the rectal temperature to rise to values in a range from 38.4 to 39.4°C, substantial sweating could no more be elicited by repeating the thermal stimulus. However, treadmill running for 20 min caused a further weight loss of 0.1 to 0.9 kg, although the rectal temperature now remained on an average 0.7°C lower than during the preceding exposure to heat. The mean total loss of weight during the whole procedure was 3.6 per cent of the initial body weight.The concentration of sodium, potassium and chloride varied individually at repeated exposures to heat. In most subjects, the range of the variation was small. During exercise the mean content of sodium was lower than in sweat collected during the first exposure to ambient heat.The results are discussed.
The Effect of Small Doses of Alcohol on the “Optokinetic Fusion Limit”
Authors: Blomberg Lars‐H. , Wassen Anders 
Published: December 2008

AbstractOptokinetic nystagmus was examined and registered electronystagmographically in the cases of 21 healthy subjects where the angular speed of optical stimulation was successively increased until the eyes could no longer follow the black and white bands on the optokinetic screen (the “optokinetic fusion limit”, OFL). This limit was also examined under the effect of a small dose of alcohol intravenously 0.8–1.6 g (concentration in serum of up to 5 mg/100 ml). The results showed a statistically significant decrease in OFL (P < 0.01). It is pointed out that the effect of small doses of alcohol on the eye movements is similar in certain respects to that of the barbiturates. No information concerning the exact site of action of alcohol on the central nervous system may be implied from those data.
Regional Blood Flow of the Cerebral Cortex Determined by Krypton85
Authors: INGVAR By DAVID H. , LASSEN NIELS A. 
Published: December 2008

AbstractA new method for determining regional blood flow in tissue by means of the inert radioactive gas Krypton85is presented. The method has been applied on the exposed cerebral cortex of anesthetized rabbits, cats and dogs. The radioisotope Kr85, a weak beta emitter, was dissolved in saline which was then injected into the carotid artery of the hemisphere to be studied. The rapid uptake and slower clearance of the isotope was recorded from a small area of the exposed cortical surface, about 1 mm in depth. The theory of analyzing the clearance curves and of calculating the average regional cortical blood flow in ml per gram per minute is described. The method requires constant blood flow in the tissue during the measurement (about 5 min). It may, however, to some extent be used for studies of acute changes in perfusion. It is also possible to use it in a continuous fashion. It has been possible to confirm and to study in quantitative terms the correlation between arterial carbon dioxide tension or cortical functional activity, and the regional cortical blood flow. The method is simple to use and permits repeated measurements in the same experiment with minimal interference with the functional activity of the brain. The method may readily be adapted for studies in man
Regional Cerebral Cortical Metabolic Rate of Oxygen and Carbon Dioxide, Related to the EEG in the Anesthetized Dog
Authors: Gleichmann U. , Ingvar D. H. , Lassen N. A. , Lübbers D. W. , Siesjö B. K. , Thews G. 
Published: December 2008

Abstract— The regional oxygen consumption and carbon dioxide production of a small area of the cerebral cortex (somato‐sensory cortex) in anesthetized dogs at steady state were determined quantitatively by means of a new method for measuring the regional cerebral blood flow (Lassen and Ingvar 1961, 1962) and by determination of the cortical arteriovenous difference of oxygen and carbon dioxide. Samples of cortical venous blood were obtained from the anterior part of the superior sagittal sinus after elimination of the diploic anastomoses. There were 26 complete sets of determinations. The a. v. differences (rAVDo1, and rAVDco2,) were found to be fairly stable (averages 11.3 and 11.7 vol. per cent). Large variations were found in the regional cortical blood flow (rCBF; 0.19 –1.06 ml per g per minute, average 0. 65 ± S.D. 0.23). The regional cortical oxygen consumption (rCMRo2 = rCBF × rAVDo2) hence varied between 2.3 and 13.4, average 7.0 (± S. D. 2.8), ml per 100 g tissue per minute. Studies of the EEG patterns prevailing at the time of the determinations showed that an EEG pattern dominated by faster frequencies (5–12 cycles per second) had an average rCMRo2, of 8.6 ml per 100 g per minute. A pattern dominated by high voltage slow waves (0.5 to 4 cycles per second) showed an average of 5.0, and a mixed EEG pattern of fast and slow waves an average rCMRo2 of 6.8 ml per 100 g per minute.
Formation of Phenolic Acids in Brain after Administration of 3,4‐Dihydroxyphenylalanine
Authors: Carlsson Arvid , Hillarp Nils‐Åke 
Published: December 2008

Abstract— When L‐DOPA (100 mg/kg body wt.) was given i.v. to rabbits large amounts of first 3,4‐dihydroxyphenyl‐acetic acid (DOPAC) and then homovanillic acid rapidly accumulated in the brain stem. The data suggest that the dopamine formed in the brain from the administered DOPA first reaches sites of monoamine oxidase. The DOPAC thus formed then reaches sites of catechol‐O‐methyl transferase. The data also suggest that the accumulated phenolic acids do not easily escape from the brain to the blood.
Heat Exchange Through the Muskrat Tail. Evidence for Vasodilator Nerves to the Skin
Authors: Johansen Kjell 
Published: December 2008

AbstractThe importance of peripheral vascular adjustments in the regulation of thermal balance has been studied in 25 adult muskrats. This animal has a pelage of high insulative value while the tail is naked. The importance of the naked tail for maintenance of thermal balance was studied by plethysmographic techniques and measurements of tail and rectal temperatures. When subjecting the animal to a positive heat load by general body heating or following excercise, the tail skin temperatures rose to 35–37° C. Tail blood flow increased concomitantly by a factor of more than 400. The vasodilatation and subsequent increase in tail blood flow prevented heat accumulation and increase in rectal temperature during the positive heat load. Nerve block of the tail before heating or excercise precluded the described increase in tail blood flow and hyperthermia resulted. Nerve block at maximum blood flow led to a prompt decrease in tail temperature and a rapid increase in rectal temperature. It is concluded that the muskrat tail is an indispensible heat exchanger, reducing excess heat from increased metabolism or general body heating. The data indicate that the conspicious changes in tail blood flow are mediated through a sympathetic vasodilator mechanism.
Effect of Methanol, N‐Propanol and Acetaldehyde on Oxygen Uptake and on Blood Glucose Concentration in Anesthetized Rabbits
Authors: Perman E. S. 
Published: December 2008

AbstractIncreases in oxygen uptake and in blood glucose concentration after ethanol administration have recently been demonstrated in urethane‐anesthetized rabbits. The present experiments were performed to determine whether substances related to ethanol produce similar effects. The substances were infused intravenously. — Methanol and n‐propanol did not affect the oxygen uptake in doses comparable to the effective ethanol doses. This suggests that the effect of ethanol on oxygen uptake is not common to lower primary alcohols. Acetaldehyde, the chief primary ethanol metabolite, increased oxygen uptake in a smaller dose. It is tentatively suggested that acetaldehyde is involved in the production of increased oxygen uptake noted after ethanol. – Blood glucose increased only after methanol administration. The increase was not abolished by ganglionic blockade, suggesting that methanol and ethanol raise the blood glucose level via different mechanisms.
The Effect of Oxygen at High Pressure on the Histology of the Central Nervous System and Sympathetic and Endocrine Cells
Authors: Edström J.‐E. , Röckert H. 
Published: December 2008

AbstractRats were exposed to oxygen at 6 atm daily for about 8 weeks in one series and for 4 weeks in a second series. The exposure times were so adjusted as to give a low incidence of convulsions and lung symptoms. The treated animals did not show any evidence of lung damage at autopsy. Slight motor symptoms of a paralytic nature developed in some of the rats of the first series after about 2 weeks. The symptoms regressed during the continued treatment and had disappeared after further 5 weeks. Histological investigation of the nervous system after 7 to 9 weeks showed no degeneration. The rats of the second series exhibited no neurogenic symptoms. The exposures to high oxygen tension were found to have an action on the sympathetic nervous system resulting in an increased size of the nucleolus of neurons of the stellate ganglion and the adrenal medulla. In both series there was a decrease in the weight of the thymus, but the reduction was significant in the second series only. In agreement with earlier investigators a weight increase of the adrenals was found (P < 0.05 for the first series), and histologically, a thickening of the zonal fasciculata. A weight increase of the same statistical significance was obtained also for the thyroid. The histology of the pituitary was unchanged. Determinations of ribonucleic acid and size of nucleolus in the supraoptic nucleus did not reveal any changes. The investigation, consequently, could not provide any evidence for a direct degenerative action of OHP on the central nervous system. The observed changes are characteristic for a stress reaction. However, the weight increase of the thyroid is not typical for stress and may be an expression of a specific OHP effect.
Self‐Stimulation in the Goat
Authors: Persson Nils 
Published: December 2008

AbstractA method is described to obtain intracerebral self‐stimulation in the goat. Permanent platinum iridium electrodes were implanted into the hypothalamus. The animal could elicit the electrical stimuli by pressing a switch connected to a stimulator that delivered trains of damped square pulses to the electrodes. High rates of self‐stimulation were obtained in the premamillary region of the hypothalamus between columna fornices descendens and tractus mamillothalamicus. The behaviour of the goats during self‐stimulation was observed, as well as the different rates and frequencies of self‐stimulation that they developed at various electrode sites. The influence of different strengths of current on the rate of self‐stimulation was also observed. In some parts where high rates of self‐stimulation were obtained, an increase in current strength up to 1.0 mA did not decrease the rate of self‐stimulation. A sudden change to stimuli in “rewarding areas” that never before had been tested with electric current immediately developed high rates of self‐stimulation. Amphetamine was tested on self‐stimulating animals. The drug increased the animals' urge for self‐stimulation.
The Solubility of Carbon Dioxide in Cerebral Cortical Tissue of Cats With a note on the solubility of carbon dioxide in water, 0.16 M NaCl and cerebrospinal fluid.
Authors: Siesjö Bo K. 
Published: December 2008

AbstractThe solubility of carbon dioxide in cerebral cortical tissue from cats was determined in homogenates, acidified to pH < 4 (cf. van Slyke, Sendroy, Hastings and Neill, 1928). The homogenates, which were prepared from brains frozen in situ with liquid nitrogen, were equilibrated with pure carbon dioxide at 37.5° C. The carbon dioxide content of the homogenates was determined by the microdiffusion method of Conway (1950) and the resulting Kuenen coefficients (ml CO2/g and ml CO2/g of H2O) calculated. A linear relationship was found between solubility coefficient and tissue concentration in the homogenates. Extrapolation to undiluted tissue gave the coefficients 0.49 (ml CO2/g tissue) and 0.61 (ml CO2/g of H2O in the tissue) respectively. The solubility of carbon dioxide in the tissue followed Henry's law, which should indicate that no appreciable amount of carbon dioxide is adsorbed onto tissue constituents. Measurement of the solubility coefficient for carbon dioxide in cerebrospinal fluid at 37.5° C revealed that this coefficient came very close to that obtained in a 0.16 M NaCl solution. The solubility coefficient in water, originally determined to test the methods used, was in good agreement with two, but in less good agreement with the majority of the coefficients reported in the literature. An examination of the literature indicated a source of error in the determination of the latter values.
The Reliability and Validity of a Physical Work Test
Authors: Borg Gunnar , Dahlström Hans 
Published: December 2008

AbstractThis investigation deals with the reliability and validity of different measurements of importance for the physical working capacity. Some physiological variables,e. g.pulse rate during a work test, have been correlated with each other, with some morphological variables and with an independent external criterion of the physical working capacity in the form of results from a skiing competition. The reliability of the work test on the bicycle ergometer was shown to be very high with intra‐test correlations as high as r = 0.97 and re‐test correlations (after about 8 months) r = 0.75. The highest validity correlation was 0.54 thus showing the usefulness of the work test on the bicycle ergometer.
Further Observations on the Effect of Anoxia on Histamine Release from Guinea‐Pig and Rat Lung Tissue in Vitro
Authors: Diamant Bertil 
Published: December 2008

AbstractHistamine release was induced in vitro by antigen from sensitized guinea‐pig and rat lung tissue, and by compound 48/80 and Ascaris extract from non‐sensitized rat lung tissue. Preexposure of the lung tissue to nitrogen anoxia in the absence of glucose (“pre‐incubation”) markedly inhibited histamine release subsequently elicited under nitrogen in the presence of glucose, or under oxygen in its absence, whereas the same procedure had a comparatively smaller effect on histamine release induced under oxygen in the presence of glucose. Washing the lung tissue after“pre‐incubation” enhanced the histamine release subsequently induced under nitrogen with glucose, whereas histamine release under oxygen with or without glucose was less affected by the washing procedure. Rat and guinea‐pig lung tissue exposed to compound 48/80 and antigen, respectively, during“pre‐incubation” was found to be insensitive to a second exposure to the same histamine releaser. The results are explained on the assumption that high‐energy compounds available at the time of exposure of the lung tissue to the histamine‐releasing agents are of consequence for histamine release to proceed. They also suggest that the initial reaction (coupling of antigen to antibodies and of compound 48/80 to active sites) occurs without involvement of high‐energy compounds.
Competitive Effects of Sympathetic Control and Tissue Metabolites on Resistance and Capacitance Vessels and Capillary Filtration in Skeletal Muscle
Authors: Lewis David H. , Mellander Stefan 
Published: December 2008

AbstractReduction in regional blood flow to skeletal muscle impairs and eventually abolishes the responses of the resistance and capacitance vessels to both sympathetic vasoconstrictor nerve fibre activation and close intraarterial infusion of l‐noradrenaline. The resistance response declines more rapidly and is abolished earlier than the capacitance response. The more severe the degree of flow reduction the more rapid is the decline and the shorter is the time to abolition of both responses. Increased frequency of nerve stimulation and increased dosage of noradrenaline produce greater responses and can ‘protect’ reactivity, temporarily, against the effects of flow reduction. This protection is greater for the capacitance response than for the resistance response. Flow reduction also impairs precapillary resistance to a greater degree and more rapidly than postcapillary resistance. This interferes with and eventually abolishes the normal ability of the nerves to decrease mean capillary hydrostatic pressure and, thereby, to cause a net inward movement of extravascular fluid. Retention of postcapillary resistance response beyond that of precapillary results eventually in an outward movement of fluid on nerve stimulation. The data indicate that precapillary responses (precapillary resistance vessels, precapillary sphincters) are more under the influence of local dilating metabolic factors than are postcapillary responses (postcapillary resistance vessels, major capacitance vessels) which, in turn, are more dominated by extrinsic nervous factors. These observations provide a more precise understanding of the regulation of the local circulation and may aid in explaining the nature of the circulatory derangement in shock.
Distribution of Ingested Palmitic Acid‐1‐C14 between Rat Serum Lipoprotein Fractions
Authors: Karvinen Esko , Koskimies Olli , Miettinen Matti 
Published: December 2008

AbstractUptake of palmitic acid‐1‐C14 in albumin plus α1 lipoprotein fraction, in α2 lipoprotein, SbT lipoprotein and chylomicron fractions separated by paper electrophoresis was followed from 3 to 76 hours after oral administration of palmitic acid‐1‐C14. Except the initial high activity in the chylomicrons, the highest activity was found in the albumin plus α1 lipoprotein fraction. Apparent turnover time of this fraction between 3 and 18 hours after ingestion of the label was about 12 hours. Activity of the α2 lipoprotein fraction was not much altered up to 28 hours. Activity of the β lipoprotein fraction seemed to follow the activity of the chylomicron fraction to a greater extent.
Relative Adrenaline Content in Brain Tissue
Authors: Gunne Lars‐M. 
Published: December 2008

AbstractFollowing chromatographic separation on a weak cation exchange resin (Amberlite IRC 50) adrenaline was identified in the brains of hens, pigs and rats by means of 1) the ethylene diamine condensation method, 2) the trihydroxyindole method and 3) bioassay on the hen's rectal caecum and cat's blood pressure. The percentage adrenaline in these species varied from 4,5 to 17. In brains of oxen and guinea pigs no adrenaline was detected, indicating less than 4 per cent adrenaline in these species.
The Relation Between Stimulus and Discharge in a Rapidly Adapting Touch Receptor
Authors: Lindblom U. 
Published: December 2008

AbstractA quantitative experimental analysis was made in decerebrate toads of the relation between stimulus and discharge in touch receptors of the common rapidly adapting type. The stimuli consisted of mechanical pulses of variable slope, amplitude and duration. Recording was made from single afferent fibres in the dorsal root. The impulse frequency of the discharge from the very rapidly adapting receptors, and of the dynamic discharge from the less rapidly adapting receptors, varied with the gradient of the stimulus in a characteristic way. When the rate of the displacement was successively increased from the minimum effective value (critical slope), the impulse frequency was low at first, and then rose as a logarithmic function of the displacement rate (Fig. 2, 3, 5 and 6). The range of rates in which the change in frequency occurred was called the optimal slope range of the receptor. The impulse frequency was independent of the amplitude of the displacement in the very rapidly adapting receptors (Fig. 1 and 3 B), and only partially related to it in the less rapidly adapting ones. The demonstrated relation between displacement rate and discharge frequency constitutes a basis for an exact reproduction of the temporal characteristics of the stimuli and may be of primary importance for tactile discrimination.
Der Einfluss chronischer Hypoxie entsprechend 1,000 — 8,000 m Höhe auf die Erythropoiese der Ratte
Authors: Tribukait Bernhard 
Published: December 2008

AbstractA device is described for the maintenance of a constant low air pressure. Rats were held under hypoxia equivalent to 1,000—8,000 m altitude for several months. Total hemoglobin was determined according to a modified alveolar CO‐method. Total hemoglobin at sea level was about 0.75 g/100 g body weight, increased significantly at 1,000 m and to 1.1 g at 4,000 m. A maximum of 2.2 g was at 6,000 m. The limit of survival was reached at 8,000 m. New levels of total hemoglobin was reached after 20 and 40 days at 5,000 respectively 6,000 m. An additional supply of iron had no effect. Hemoglobin per 100 ml. blood was 14, 19 and 26 g at sea level, 4,000 respectively 6,000 m. Hematocrite was 45 % at sea level, 60 % and 85 % at 4,000 m and 6,000 m respectively. Hemoglobin concentration parallels hematocrite values during hypoxia. Blood volume increased by 20—50 % at 6,000 m but plasma volume decreased by 10—20 %. Hemoglobin per unit body weight decreased with increasing body weight in animals adapted to 5,000 and 6,000 m, also the blood volume at 6,000 m. The daily production of hemoglobin was calculated from the total hemoglobin and the assumed life span of 60 days for erythrocytes. It increased to 4—5 times the normal during the first two days regardless of degree of hypoxia, but was thereafter a function of the degree of hypoxia.
Reflex Responses and Recurrent Discharges Evoked by Stimulation of Laryngeal Nerves
Authors: Maåtensson A. 
Published: December 2008

AbstractReflex responses in intrinsic laryngeal muscles to stimulation of the internal laryngeal nerve were studied with a view to elucidating the mechanism of the protective reflex closure of the glottislpsilateral stimulation evoked reflex discharges of multisynaptic character in all four vocal cord adductors studied but never in the abductor in which only inhibition of pre‐existent activity was observed. Contralateral stimulation evoked similar reciprocal effects but the discharges in the adductors were smaller and of longer latencies and did not appear in all muscles; latent contralateral reflex connections could, however, be demonstrated in all muscles. The reciprocal innervation pattern and the difference in transmitter potentiality of different reflex connections are discussed. 2/ Proprioceptive mechanisms in the laryngeal musculature were investigated. Stimulation of individual muscle nerves evoked, in nerve and muscle, in addition to the direct response, a secondary response amounting to a few per cent of the primary response. By performing an analysis in analogy with previous work on the spinal cord it was concluded that the secondary response represented a recurrent discharge from the motoneurons, whereas no response exhibiting the properties of a monosynaptic reflex was observed. Attempts to record afferent impulses from muscle spindles gave negative results. The findings are discussed in relation to earlier results from morphological and physiological studies of proprioceptive systems in the larynx.