bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Occurrence of ß‐Garotene in Blood Cells from Cattle
Authors: Nilsson Bo 
Published: December 2008

AbstractBlood cells were prepared from cattle, sucking calves and pigs and the chief part of the hemoglobin was removed by hemolysis. The remains were disintegrated with ultrasonic vibration and extracted with phosphate buffer after which they were freeze‐dried and finally extracted with iso‐octane. Spectrophotometrical registrations of the iso‐octane extracts obtained from blood cells of adult cattle showed that the extracs contained β‐carotene. The concentration of β‐carotene in the disintegrated blood cells was estimated at about 0.5 mg%. In cattle β‐carotene thus occurs not only in the blood plasma, as stated in the literaure, but also in the blood cells. The iso‐octane extracts obtained from blood cells of sucking calves or pigs contained no measurable quantities of β‐carotene on account of which the β‐carotene in the blood cells from adult cattle seems to derive from the fodder.
Postnatal Excitability Changes of Kitten Motoneurones
Authors: Kellerth Jan‐Olof , Mellström Anders , Skoglund Sten 
Published: December 2008

AbstractThe responses of lumbosacral motoneurones to iterative dorsal root (DR) stimulation were studied in unanesthetized, spinalized kittens and adult cats by means of intracellular microelectrodes. The resting membrane potentials were found to increase in magnitude from birth up to 1.5 months of age. The action potentials increased in amplitude but decreased in duration with increasing age. In young kittens many cells, for several reasons considered to be motoneurones, failed to be invaded by antidromic spikes. In kittens less than 10 days old the majority of the action potentials did not show an overshoot. The amplitude of orthodromic spikes could be varied in kittens by varying the stimulation strength, probably due to summation of dendritic spikes. In young kittens supramaximal DR stimulation produced large depolarizations which generally decreased in magnitude with increasing age. Spikes elicited during such depolarization were often considerably reduced in amplitude (sometimes more than 50%). In young kittens almost all neurones responded with a monosynaptic spike to each DR‐stimulus at a frequency of 2/sec. This property gradually disappeared with increasing age, especially in extensor motoneurones. The findings are discussed in the light of some recent studies on the postnatal changes in morphology and physiology of the cat spinal cord.
ATP Hydrolysis and Noradrenaline Transport in Purified Vesicles from Splenic Nerve Trunk
Authors: Klein Richard L. , Lagercrantz Hugo 
Published: December 2008

AbstractA fraction of highly purified noradrenaline (NA) storage vesicles isolated from bovine splenic nerve trunk was tested for ATP hydrolytic activity. At 37.5† C and pH 7.2, the specific activity of Mg++‐ and Ca++‐activated hydrolyses were 0.22 and 0.15 μM P1/mg protein/min, respectively. There was no hydrolysis in the absence of divalent cations. The additions of various combinations of Na+ and K+ salts had little effect. Concentrations of NA and dopamine between 0.1 and 10.0 μg/ml had no effect. A concentration of 5×10‐8 M reserpine, which produced 30–50% inhibition of NA exchangeability and influx rate, had no effect on ATP hydrolysis under a wide variety of conditions. This concentration of drug causes no obvious evidence of vesicle damage at the electron microscopic level. The data do not support the possibility of a link between ATP hydrolysis and NA transport in either direction across the membrane of the isolated nerve trunk vesicle.
Studies on the Site and Mechanism of Action of the Growth Inhibiting Effects of Estrogens
Authors: Herbai Georg 
Published: December 2008

AbstractThe effect of estrogens and growth hormone on the incorporation rate of sulfate into costal cartilage of the mouse was studiedin vivoandin vitroin normal, starving and hypophysectomized animals. Growth hormone was unable to counteract estrogen‐induced inhibition of sulfate incorporationin vivo.Starvation of the mice elicited a depression of sulfate uptakein vivo, but a simultaneous estrogen treatment caused a further decrease in sulfate incorporation in the starving mice. Sulfate incorporation into costal cartilage samplesin vitrowas markedly inhibited in the presence of estrogen in the incubation medium. Costal cartilage samples from hypophysectomized mice incorporated less35S‐sulfate than those from the controls, but estrogen in the medium caused no further decrease in sulfate uptake. Incorporation rates of3H‐acetate and35S‐sulfate were reduced to a similar degree by estrogen in the medium. It is concluded that estrogen‐induced inhibition of growth is neither due to growth hormone deficiency, nor to an appetite diminishing effect of the hormones. Estrogens exert a local inhibitory effect on sulfate (and acetate) incorporation in the chondrocytes and growth stimulation of the cells is a necessary condition for the appearance of the inhibiting actions of estrogens.
Renal Vascular Resistance in Spontaneously Hypertensive Rats
Authors: Folkow Björn , Hallbäck Margareta , Lundgren Yen , Weiss Lilian 
Published: December 2008

AbstractThe renal vascular beds of one spontaneously hypertensive rat (SHR) and one matched normotensive control rat (NCR) were perfused with oxygenated plasma substitute in 27 paired expts. Pressure‐flow curves indicated that the renal vascular resistance is lower in SHR than in NCR during maximal dilatation, in contrast to the situation in other major circuits, while the SHR renal resistance vessels are less distensible than those of NCR.–Graded noradrenaline (NA) infusions showed that the NA threshold does not differ significantly between the two groups, but SHR displays a steeper dose‐response curve and an increased maximal pressor response as compared to NCR.–The results suggest an increased media thickness in the SHR renal resistance vessels, raising their wall/lumen ratio, “reactivity” and maximal contractile strength but reducing their distensibility. However, while the thickened vascular walls in other major circuits encroach upon the lumina, even at maximal dilatation (Folkowet. al.1970 a, b), they are in the kidneys combined with increased vascular lumina. This implies a larger renal blood supply in SHR than in NCR at very low level of vascular tone while the reverse is true at enhanced tone, due to the steeper resistance curve in the SHR.
Effect of Angiotensin on Plasma‐Free Fatty Acids in Dogs
Authors: Akre Stein , Mjøs Ole Danbolt 
Published: December 2008

AbstractMechanisms underlying the plasma‐free fatty acids (FFA) lowering effect of angiotensin have been studied in anesthetized dogs. Angiotensin in pressor doses reduced fatty tissue blood flow (FBF) as well as plasma‐FFA. After ganglionic blockade, angiotensin had the opposite effects, as a slight increase was found in FBF and plasma‐FFA. Atropine or a β‐adrenergic blocking agent did not interfere with the angiotensin effect on plasma‐FFA. It is concluded that the angiotensin action on plasma FFA is secondary to its vasoconstrictive effect in adipose tissue.
Salivary Secretion in the Rat in a Hot Environment
Authors: Elmér Mats , Ohlin Per 
Published: December 2008

AbstractConscious rats were found to secrete saliva from the submaxillary gland when exposed to heat. In rats with sympathetically denervated glands the secretory rate was a little lower and in parasympathetically denervated glands the secretion was almost abolished. The salivary flow appeared to increase with increasing ambient temperature and the secretion started earlier at higher temperatures. The secretion elicited by heat stress was compared to the secretion evoked by electrical stimulation of the parasympathetic nerve to the gland. It is concluded that the salivary secretion evoked by heat stress is mainly mediated by the parasympathetic secretory nerves, although the sympathetic fibres also take part.
The Intracellular pH‘ in the Brain in Acute and Sustained Hypercapnia
Authors: Messeter Kenneth , Siesjö Bo K. 
Published: December 2008

AbstractThe regulation of intracellular pH′ in the brain was studied in rats exposed to about 11% CO2 for periods of 15 min to 72 h. At the end of each exposure period cisternal cerebrospinal fluid, as well as the supratentorial parts of the brain, were sampled and analysed for the CO2 contents. The intracellular HCO3‐ concentration was calculated assuming extracellular volumes of 12, 15 and 20%, respectively, and the intracellular pH′ was derived from the HCO3‐ concentration and the mean tissue CO2 tension. Acute hypercapnia (15 min) was associated with an increase in the intracellular HCO3‐ concentration of about 6 meq/kg of i.e. water. With an extracellular volume of 15% the corresponding decrease in pH′i was from 7.06 to 6.93. When the hypercapnia was upheld there was a further increase in the intracellular HCO3‐ concentration of about 5 meq/kg and an increase in pH′i to about 7.03. Most, if not all, of this regulation of pH′i occurred during the first 3 h. An analysis of the regulating mechanisms suggests that physicochemical buffering, metabolic consumption of acids, and transmembrane fluxes of H+ or HCO3‐ each contributed about a third of the total accumulation of bicarbonate in the cell during hypercapnia.
Characterization of Simple and Composite Uptake Systems in Cells and Tissues by Competition Experiments
Authors: Bárány Ernst H. 
Published: December 2008

AbstractThe first step of active uptake of a substance is taken to be the reversible combination with a primary binding site (receptor) by a first order reaction. Such a binding is characterized by an affinity constant. Several kinds of receptors can be simultaneously present in a cell or tissue: one then has a composite uptake system. Each receptor is characterized by an affinity spectrum, a list of its affinities to all possible substances with any affinity. Naturally, such a list can never be complete. The affinity spectrum can be obtained by means of a single test substance which the tissue is allowed to accumulate and which is analyzed in the tissue while the affinities of all other substances are measured by their ability competitively to depress the uptake of the test substance. For these substances, only the concentrations in the medium are required. The mathematics of such competition experiments are derived for a simple and for a composite system consisting of two independent systems with completely overlapping but not identical affinity spectra. A formula is derived which allows one to estimate the affinities of any substance to the two receptor systems by measurements at four concentrations of the substance. In the case of incompletely overlapping affinity spectra, the systems can either be studied separately or as if there were complete overlap.
Uptake of Micellar Lipids by Small Intestinal Segments [under Different Experimental Conditions].
Authors: Sylvén Christer 
Published: December 2008

AbstractUptake of radioactive cholesterol, sitosterol and monoolein from micellar solutions was studied under different conditions in rat small intestinal segments both with and without blood supply, and in inverted segments in vitro. The Na+/K+ ratio of the micellar test solution did not influence the uptake of any species of lipid tested. In vivo the uptake of sterols was maximal at 37°C. It had a Q10 of about 3. Three states of sterol uptake were observed. (1) A high uptake of both cholesterol and sitosterol, (2) a low uptake of both sterols, and (3) a low uptake of sitosterol with a high uptake of cholesterol. The latter state corresponds to normal uptake in vivo. These states were demonstrated under different experimental conditions involving exclusion of blood supply to the small intestine, extensive hypothermic treatment of the rat, extensive hypothermic treatment followed by rewarming to 37°C, and biliary drainage followed by uptake experiments with high concentrations of NaTDC or NaTC. It was demonstrated that the normal uptake of sterols could be both irreversibly and reversibly changed into the other abnormal states of uptake.
Uptake of Serotonin in Blood Platelets in vitro. III: Effects of Acetate and Other Monocarboxylic Acids
Authors: Lingjærde O. 
Published: December 2008

AbstractThe chloride‐dependent uptake of serotonin in human blood platelets is stimulated by acetate, maximal effect being obtained with about 10–15 mM acetate at pH 7.3. In the absence of chloride (or other halogen anions), acetate has no effect on serotonin uptake. The stimulatory effect of acetate seems to be mainly due to an increased affinity of the “anionic site” of the 5HT carrier for chloride. Acetate conceiveably reacts with the hypothetical “activating site” on the plasma membrane in the same way as was previously shown to be the case for nitrite. The specific activating effect of both acetate and nitrite is blocked by increasing the extracellular potassium concentration to about 30 mM. At pH 6.2, acetate in concentrations higher than about 10 mM exerts an uncompetitive inhibitory effect on serotonin uptake. This effect is not counteracted by potassium, and seems to be quite independent of the stimulatory effect. The stimulatory effect of acetate on serotonin uptake is shared by other monocarboxylic acids, such as formate, propionate, butyrate, lactate, and pyruvate. The possibility that lactate may act as a physiological regulator of serotonin uptake in platelets and “serotoninergic” neurons is mentioned.
Effect of Training on Oxygen Consumption in Negative Muscular Work
Authors: Klausen K. , Knuttgen H. G. 
Published: December 2008

AbstractDuring negative work, bicycling downhill on a motordriven treadmill, it was found in 3 young, male subjects that the oxygen consumption (V&#x030a;o2) continued to increase over a 25–50 min exercise period. The increase from the 10th to the last min of exercise was more than 25%. After 3–5 weeks of training with negative work of higher numerical work intensity, a marked decrease in V&#x030a;o2 was seen and the continuous increase in V&#x030a;o2 during the exercise period was reduced to a minimum, when the subjects worked at the same work intensity as before the training period. The direct employment of energy received by the muscles during negative work in the contraction process is discussed as a possible explanation for the reduced aerobic metabolism. Strengthening of the connective tissue during training and changes in muscle viscosity due to changes in muscle temperature are suggested as other possible factors involved in the decrease in V&#x030a;o2.
The Metabolism of Monosaccharides in Isolated Rat Mast Cells and its Influence on Histamine Release Induced by Adenosine‐5‘‐Triphosphate.
Authors: Diamant Bertil , Peterson Curt 
Published: December 2008

AbstractHistamine release from isolated rat mast cells induced by extracellularly applied ATP in the presence of calcium was enhanced by D(+)glucose and D(+)mannose, but not by D(‐)‐fructose or D(+) galactose (0.6 mM of each). Only those monosaccharides which enhanced the histamine release were metabolized by the mast cells through the Embden‐Meyerhof pathway as judged from the accumulation of lactate in samples incubated with the sugars. Lactate (1 mM) as well as pyruvate (1 mM) also enhanced the histamine release induced by ATP. Antimycin A (10‐7M) completely inhibited ATP‐induced histamine release irrespectively of the presence of glucose, pyruvate or lactate. Iodoacetate (10‐4M) blocked the enhancing effect of glucose, but not that of pyruvate or lactate. In the presence of glucose (0.6 mM) or mannose (0.6 mM) the accumulation of lactate in suspensions of rat mast cells was enhanced by antimycin A (10‐7M) and blocked by iodoacetate (10‐4M). In the absence of glycolytic substrates and metabolic inhibitors no accumulation of lactate was noted whereas in the presence of antimycin A (10‐7M) a slight but statistically significant accumulation occurred.
Effects of Noradrenaline on Activity in Single Aortic Baroreceptor Fibres
Authors: Aars Harald 
Published: December 2008

AbstractThe possibility of sympathetic control of the sensitivity of arterial baroreceptors has been examined by recording activity of single baroreceptor fibres in the rabbit's aortic nerve before and during intravenous infusion of noradrenaline (4–6 μg/kg × min). Activity was related to blood pressure — which could be changed by bleeding and reinfusion of blood — and to diameter of ascending aorta measured with ultrasonic technique inside the intact thorax. At the same blood pressures as in control runs, activity of 34 single myelinated fibres (conduction velocities 10–35 m/s) was lowered by noradrenaline, on average by 1 spike per pulse beat, and diastolic aortic diameter was reduced by about 7%. When compared at equal diastolic diameters, pulsatile diameter variations were smaller with noradrenaline than in control runs, but even so, receptor activity was found to have risen by 2–3 spikes per pulse beat, i.e., up to 50 %. Thinner myelinated fibres (conduction velocities about 5 m/s) occasionally showed higher than normal activity also at comparable blood pressures. The results demonstrate that the sensitivity of aortic baroreceptors to distension of the receptor area can be increased by noradrenaline. However, as aortic diameter is simultaneously decreased, activity in most single baroreceptor fibres was slightly reduced at any given blood pressure during intravenous infusion of noradrenaline.
Differential Effect of Sleep Deprivation on the Two Slow Wave Sleep Stages in the Gat
Authors: Ursin Reidun 
Published: December 2008

AbstractThe effect of total sleep deprivation on the sleep stages and their interrelations was studied in 10 cats. EEG, EMG and eye movements were recorded for 24 h after 12 h and 24 h sleep deprivation and after no sleep deprivation. Sleep was divided into three stages: Light slow wave sleep (LSWS), deep slow wave sleep (DSWS) and rapid eye movement (REM) sleep. The total quantities of DSWS and REM sleep in the 24 h recordings increased with deprivation, as did the relative proportion (per cent of total sleep) of these sleep stages. The total quantity of LSWS did not change with sleep deprivation, and the LSWS per cent of total sleep decreased. The changes were most pronounced after 24 h deprivation and in the first hours of recovery sleep. Sleep deprivation reduced LSWS episode length and tended to increase DSWS and REM sleep episode length. The number of sleep cycles was increased, but the length of each cycle was not altered. The results support earlier findings of a functional dissociation between LSWS and DSWS and a functional relationship between DSWS and REM sleep.
The Distribution of the Yolk Cholesterol in the Young Chick. An Autoradiographic Study
Authors: Svanberg Olof 
Published: December 2008

Abstract 14C‐4‐cholesterol was injected into the invaginated yolks of newly hatched chicks and the distribution of the labelled molecules was recorded by autoradiography. 14C was homogeneously distributed in the yolks 1 h after the injection. After 4 h, traces of radioactivity were found in the liver and after 12 h 14C had been transported from the liver into most parts of the body. The liver content of 14C‐labelled cholesterol was very high up to 6 days after the injection. The bile was rapidly intensively labelled, and was regularly regurgitated into the gizzard. The walls of the large arteries contained significantly more 14C‐cholesterol than the surrounding tissues. Organs engaged in steroid hormone synthesis incorporated more yolk cholesterol than “inactive” tissues. In the central nervous system of the youngest chicks, radioactivity was only found to any great extent in the pineal gland, while the peripheral nerves were rapidly intensively labelled. The retention of 14C‐cholesterol after 2 months was greatest in the peripheral nerves and the white matter of the central nervous system. Starvation did not markedly influence the relative distribution pattern of labelled material during the first week after hatching.
Properties of Hematopoietic Progenitor Cells
Authors: Benestad Haakon Breien , Breivik Harald 
Published: December 2008

AbstractAssay of hematopoietic progenitor cells has been carried out with the use of quantitative diffusion chamber culturing. Some progenitor cell properties were investigated. Hydroxyurea, which kills the fraction of normal mouse bone marrow progenitor cells synthesizing DNA, was given to donor mice of different ages. This DNA‐S fraction of progenitor cells was found to be as large as or larger than the corresponding fraction of spleen colony‐forming cells. It was concluded that the progenitor cells for the formation of granulocytes in the chambers are probably mixtures of cells which can give rise to spleen colonies and of cells able to form agar colonies.In chamber cultures, formation of granulocytes and macrophages is prominent, whereas erythropoiesis is scant or absent. This differentiation pattern was not changed by adding erythropoietin to the culture inocula. Nor did admixture of antigens to the cell inocula influence the formation of granulocytes and macrophages. The chamber progenitor cell population as a whole was found to have a near average adhesiveness to glass and fibrin, when compared with normal bone marrow cells or blood leucocytes.
Relationship between Antral Acidity and Gastrin Releasing Potency of Chemical Stimulants
Authors: Andersson Sven , Elwin Carl‐Eric 
Published: December 2008

AbstractThe effect of antral acidity on gastrin releasing potency of some compounds was studied in Pavlov and Heidenhain pouch dogs. Gastrin release by an unionized stimulatory compound (ethanol) was less sensitive to changes of pH than that by ionized compounds (choline, acetylcholine) or a compound with amphoteric characteristics (glycine). All dogs showed pronounced signs of general, cholinergic activation with the highest concentration of choline at pH 7 in the dose‐response curve indicating absorption through the antral mucous membrane. Absorption of choline showed pH dependency and no signs of cholinergic excitation were obtained at pH 5 or below. At low pH levels (pH 1–2) acid may produce a general, physiological insensitivity of the gastrin release mechanism to all stimuli and at higher pH levels the action of acid most likely includes effects related to changes of ionization and absorption of stimuli. In comparison with maximal acid output to intravenous histamine, choline was found to be the most potent compound under study. Responses to 4 % choline solutions at pH 7 reached the same level and responses at pH 5 exceeded the maximal histamine response. Responses to acetylcholine and glycine were 60–65 % of maximal histamine response at the most, whereas acid output to antral irrigation with ethanol only reached 1/3 of the maximal histamine response.