bluuebunny/crossref_metadata_2025 huggingface dataset:
Tonic and Phasic Ventral Horn Cells Differentiated by Post‐Tetanic Potentiation in Cat Extensors.
Authors: GRANT RAGNAR , HENATSCH H.‐D. , STEG GORAN
Published: December 2008

In decerebrate cats stretch reflexes from the ankle extensors have been studied in 100 fibres from dissected ventral root filaments. These reflexes have been maximally facilitated by post‐tetanic potentiation, as describthd by Granit (1956 a).

In the post‐tetanic or potcwtiated state the reflexes to a constant 10 mm stretch haw been found to fall into two main categories: (i) tonic reflexes which go on firing for a long duration in maintained stretch and (ii) phasic ones which only fire one or two spikes on the rising phase of stretch, in spite of any amount of post‐tetanic potentiatioit.

Analysis of spike size showed that the tonic ventral horn cells tended to fire smaller spikes than the phasic ones. From this it was concluded that the tonic motoneurones tend to group themselves among the smaller ventral horn cells.

The difference between tonic and phasic ventral horn cells was maintained when the extensor tonus was raised by decortications of the anterior lobe of the cerebellum.
Shock Wave Transmission to the Central Nervous System.
Authors: CLEMEDSON CARL‐JOHAN
Published: December 2008

The transmission of air shock waves to the central nervous system was studied in rabbits by means of a barium titanate pressure transducer inserted into the brain or the spinal column.

By exposing only a part of the animale. g. the head only or the trunk to the shock wave and with the other part thoroughly protected, it was possible to show that the main part of the shock wave pressure is transmitted to the brain directly through the skull. The indirect transmission of pressure from other parts of the body to the brain is of minor importance and the rôle of the blood vessels or the spine for that transmission is insignificant.

Pressure is also propagated from the skull down through the spine but the transmission in the opposite direction, when the abdomen only is exposed is insignificant.
On the Permeability of Guinea Pig Placenta for Triiodothyronine.
Authors: LYBECK HARRY
Published: December 2008

The permeability of the guinea‐pig placenta to I131labeled triiodothyronine was investigated. Two to four hours after subcutaneous administration of the substance, samples were taken and counted. A significant difference in radioactivity was demonstrable between the maternal and foetal samples. The results indicate that the placenta is virtually impermeable to exogenous triiodothyronine in the first hours after its subcutaneous administration.
Determination of Carbon Monoxide in Small Gas Volumes
Authors: LINDERHOLM H. , SJÖSTRAND T.
Published: December 2008

A method is described for analysis of CO in small gas volumes with hopcalite CO‐meters. By the use of electrical temperature measurement and registration with direct writing potentiometers the applicability of these CO‐meters has been greatly increased. Amounts of pure CO, from about 0.001 ml up to about 1 ml, can be measured with marked accuracy in gas volumes from 0.02 to about 500 ml irrespective of the CO concentration. Accurate calibration can be obtained by comparison with 100 per cent CO without dilution procedures. The method was found especially suitable for analysis of small amounts of CO extracted from blood samples.
Some Laboratory Data on Hedgehogs, Hibernating and Non‐hibernating
Authors: BIÖRCK GUNNAR , JOHANESON BENGT , VEIGE STEN
Published: December 2008

Comparative biochemical studies have been performed in hibernating hedgehogs in January and March and in non‐hibernating hedgehogs in June.

Red blood corpuscles and hemoglobin level were lower in March in comparison to January and June when the difference was slight. Also the hematocrit values were lower in March compared with January, while the values in June lay between these. The leucocytes decreased during hibernation but the differential leucocyte count did not change markedly except for the eosinophils which decreased comparatively more than the other leucocytes. Also reticulocytes decreased but blood platelets increased.

The blood sugar decreased as did the protein‐bound iodine. — No significant changes in serum potassium or sodium were found.

At electrophoresis an increase of the albumin fraction was found, while β1‐,β2‐ and γ‐globulins decreased.

From the tissue studies — made on hibernating hedgehogs in late February to early March and on non‐hibernating ones in September — it can be seen that the magnesium content of the heart was lower during winter; the cytochrome c content, however, did not change.

Sugar, aceton or aceto‐acetic acid were not found in the urine. Urinary albumin, however, appeared in all the hibernating animals and in half of the non‐hibernating ones.

Part of this study was supported by a grant from the Medical Research Fund of the Swedish Life Insurance Companies. Our thanks are due to the head and personal of the Central Chemical Laboratory of Allmänna Sjukhuset and to Drs. Bengt Skanse and S. E. Björkman for valuable help in this investigation.
Experiments on the Potassium Absorption of the Erythrocytes of Rana Esculentn and Rann Temporaria after Bleeding and in Hypertonic Plasma1
Authors: ØRSKOV SØREN L.
Published: December 2008

It is shown that the erythrocytes of ranae esculentae and temporariae behave very much as those from pigeons.

The blood taken from the neck of the frogs shows a marked, and in some cases a very rapid absorption of potassium from the plasma. If the frogs are cooled (2°) for an hour before the bleeding the erythrocytes show no spontaneous absorption.

Addition of hypertonic sodium chloride solution is followed by a potassium absorption of the red blood cells.
Histamine and Mast Cells.l: Studies on Living Connective Tissue in the Hamster Cheek Pouch
Authors: ASBOE‐HANSEN G. , WEGELIUS OTTO
Published: December 2008

The reaction of the mast cells to histamine, the chemical histamine‐liberators compound 48/80 and stilbamidine, peptone and water was studied in living connective tissue of the hamster cheek pouch. Degradation of the cells was invariably observed and occasionally irreversible disruption. The degranulation is interpreted as a response to increased tissue fluid, which in turn may be due to increased capillary permeability. The mucopoly‐saccharide‐containing granular substance of the mast cells may bind extracellular water and thus maintain the gel structure of the connective‐tissue ground substance. This view unites the results of previous experiments on the relation of the mast cells to histamine as well as to tissue mucopolysaccharides.
Influence of Cholesterol Feeding on the Distribution of Polyenoic Fatty Acids in the Liver of Chicks
Authors: DAM HENRIK , NIELSEN GUNHILD KOFOED
Published: December 2008

Feeding of cholesterol at a dietary level of 1 % together with 10 or 20 % peanut oil to chicks caused a decrease in the amount of tetraenoic acid in the liver. especially when expressed as per cent of total fatty acids.

When the diet did not contain fat. 1 % cholesterol had no influence on the amount of liver tetraenoic acid.

Liver pentaenoic acid and hexaenoic acids. the amounts of which were low under the conditions of the experiment. seemed to be influenced in the same direction as tetraenoic.

No significant change in liver dienoic or trienoic acids expressed as per cent of total fatty acids was found as a consequence of feeding 1 % cholesterol. When expressed as mg per g liver or per whole liver dienoic increased when 1 % cholesterol was fed with 10 or 20 % peanut oil.
Quantitative Aspects of the Sympathetic Neuro‐hormonal Control of the Heart Rate
Authors: FOLKOW BJÖRN , LÖFVING BIRGER , MELLANDER STEFAN
Published: December 2008

In cats stimulation of the accelerans nerves exerts a much stronger effect on the heart rate than the hormones released at a similar activation of the adrenal medullas. This is in accordance with the characteristics of the sympatho‐adrenal control of other autonomic effectors.

The heart response is sometimes seen to vanish quite rapidly on interruption of a low‐frequency accelerans nerve stimulation. It is therefore discussed whether the prompt reflex decreases of stroke volume, known to occur on baroceptor stimulation in man, really necessitate the assumption of a direct vagal control of the heart ventricles. It is after all not impossible that this is the consequence of an inhibition of a tonic sympathetic influence on the heart and adjacent capacity vessels, factors which both must result in some decrease of stroke volume.
Water and Food Intake and the Inhibitory Effect of Amphetamine on Drinking and Eating before and after “Prefrontal Lobotomy” in Dogs
Authors: ANDERSSON B. , LARSSON S.
Published: December 2008

A complete section through the forebrain through and just anterior to the orbital sulcus and directed well anterior to the caput of the caudate nucleus was not seen to primarily reduce the water intake of dogs or to cause any reduction in the amount of water drunk by the animals subsequent to the intravenous injection of a certain amount of hypertonic saline. The latter was temporarily the case in one animal where the lesion was extended in ventro‐caudal direction to involve the preoptic area on both sides.

 Amphetamine (1 mg per kg of body weight) completely inhibited the drinking of water after an intravenous injection of 20 cc of a 20 % NaCl solution in 4 of 5 normal dogs tested. This was no longer the case in 3 of these animals after “prefrontal lobotomy”.

 An incomplete section through the forebrain in 5 out of 8 dogs made that the dose of amphetamine necessary to inhibit, the food intake of the animals completely had to be increased by 50 to 100 %.
The Influence of Different Ions on the Intestinal Absorption of Sodium and Chloride
Authors: BUDOLFSEN SV. E.
Published: December 2008

Previously it was found that the chloride as well as the sodium ions could be absorbed against a concentration gradient in the colon and the distal part of the small intestine of rats when pure sodium chloride solutions were infused. In this paper it is demonstrated that the chloride ion is still absorbed against a concentration gradient in the colon when sodium is replaced by potassium, calcium, magnesium or ammonium, and that sodium, too, is absorbed against a concentration gradient in the colon as well as the distal part of the small intestine when the chloride ion is replaced by acetate, nitrate, bicarbonate or sulphate ions.
The Distensibility of the Systemic Resistance Blood Vessels
Authors: FOLKOW BJöRN , LöFVING BIRGER
Published: December 2008

Tlie distensibility of the systematic resistance blood vessels has been quantitatively measured at known levels of a steady vascular tone. Their distensibility is, from a liaemodynamc point of view. considerable except at more intense vasoconstriction where the lnmen‐to‐wall ratio is decreased enough to minimize the dietending effect of the intravascular pressure.

Often, however, vascular distension is more or less balanced by adaptive changes of smooth muscle tone. Therefore. a standard pressure‐flow relationship cannot be given. as this relationship varies, not only with the region studied, but also with the level of vascular tone and reactivity.

Generally, a ‘critical closing pressure’, correlated with the prevailing tone, can only be recorded if the normally occurring, adaptive changes of smooth muscle tone are eliminated. The basis for this closing is discussed at length. Reasons are presented that it might simply be an extension of the well‐known intermittent closings of the praecapillary sphincter regions to include all parallel channels at this level. It is suggested that the complete closing of this section of the vascular tree is a consequence of a pronounced distensibility of the thin intima and muscle layers of these small vessels, where an outer limit for distension is set by a surrounding network of collagen fibrils.
Functional Organization of the Dorsal Spino‐Cerebellar Tract in the Cat
Authors: LUNDBERG A. , OSCARSSON O.
Published: December 2008

Intra‐axonal recording in Flechsig's fascieulus was used to study neurons which could be activated by electrical stimulation of group I muscle afferents. There were recorded simultaneously the mass discharge in the dissected Flechsig's fasciculus and sensory volleys with triphasic recording from dorsal roots for control of input in terms of Ia and Ib volleys. In addition adequate stimulation of stretch receptors in muscles was used in some experiments.

Ib fibres reach the region of Clarke's column via the dorsal column as do the Ia fibres.

Most of the mass discharge in the dissected Flechsig's fasciculus appears with a primary Ia volley but some increase occurs with Ib. Most neurons examined discharge on stimulation of Ia but some only when stimulation was raised to include part of Ib. In many neurons excited by Ia, a second post‐synaptic spike appeared with a Ib volley generated in the refractory period of the preceding Ia volley. Ia as well as Ib volleys were found to contribute inhibitory action to neurons excited by group I afferents from antagonist muscles.

The discharge in secondary neurons, responding to a stretch of a muscle. was examined during contraction of the muscle (soleus. gastrocnemius or quadriceps). An acceleration was found in 36 per cent, demonstrating excitatory action by Golgi tendon organ afferents, and the remainder paused during rontraction. Occasionally results were obtained indicating convergence of excitatory action from Golgi tendon organ and muscle spindle afferents.

It is concluded that some DSCT neurons subserve transmission of information from Golgi tendon organs and others from muscle spindles. The occurrence of convergence of excitatory action from muscle spindles and Golgi tendon organs is discussed.

Convergence of excitatory and inhibitory actions mediated by group I afferents from the same muscle has been encountered in some cases. It is suggested that convergence of this type is exceptional and not representative for the general pattern of synaptic organization.
Potentiation of Histamine Effects by Histamine Inhibitors in the Unanaesthetized Guinea‐Pig.
Authors: WESTLING H.
Published: December 2008

Histamine was given subcutaneously to unanaesthetized guinea pigs and its effects on the respiration were studied by counting the respiratory frequency and observing the external respiratory movements.

The respiratory symptoms caused by histamine were potentiated by some histaminase in hibitors in doses, which did not increase the responses to β‐2‐pyridylethylamine, acetylcholine or carbaminoylcholine.

The specificity of the potentiation and the parallelism found between potentiating effects and histaminase inhibiting properties of the different histaminase inhibitors suggest that the increase in histamine sensitivity was due to diminished histaminase activity.

The maximum increase in sensitivity obtained by these inhibitors was about two‐fold. The skilful technical assistance given by miss M.‐B. Johansson was highly appreciated.
Electrophysiologic and Pharnincological Observations on Trypsin‐Disintegrated Embryonic Chick Hearts Cultured in Vitro.
Authors: FANGE R. , PERSSON H. , THESLEFF S.
Published: December 2008

Summary. A suspension of living heart muscle cells has been obtained by trypsin treatment of embryonic chick hearts, and subsequently kept in tissue culture.

Both discrete single cells and cell elusters were observed in the tissue culture. Histologic preparations and electrophysiologic evidence indicated that the cell clusters have a syncytial structure.

The electrophysiologic properties of clusters of heart muscle cells in tissue culture have been investigated with the intracellular microelectrode technique.

The values for the resting and action potentials in cell clusters are found to be of the same magnitude as those reported by other investigators in the intact embryonic chick heart.

In cell clusters obtained from embryos younger than 8 days, a “prepotential” always preceded the action potential.

When occasionally the spontaneous contractions of heart cell clusters temporarily stopped it was observed that oscillatory fluctuations of the membrane potential initiated the appearance of contractions.

The effects of acetylcholine on the spontaneous frequency of contraction of cell clusters have been investigated. The spontaneous contractions of cell clusters deriving from the ventricular part of embryonic chick hearts were rarely (4 out of 110 clusters) inhibited by acetylcholine in a concentration of 104g/ml. The contractions of cell clusters obtained from the atrial part of the hearts were stopped to a considerable extent (115 out of 169 clusters) by this concentration of acetylcholine.
The Effects of Cooling the Feet and Closing the Eyes on Standing Equilibrium. Different Patterns of Standing Equilibrium in Young Adult Men and Women
Authors: ORMA E. J.
Published: December 2008

A clear sex difference in behavior in standing equilibrium has been observed. Swaying in young women is significantly wider than that in young men, and the numbness of the soles due to standing in ice water and closing the eyes noticeably increases swaying in women, but not in men. This difference between the sexes and some other observations on the maintenance of standing equilibrium can be explained by the following hypothesis: If muscular strength is great, muscular myotatic stretch reflexes are used almost exclusively in the maintenance of standing equilibrium, and in this case the amplitude of swaying is small. If muscular strength is not great, other afferent parts, the soles and sight
Some Charateristics of Goldthioglucose Obesity in the Mouse
Authors: LARSSON S. , STROM L.
Published: December 2008

1. Eating and drinking behaviour have been studied in mice made obese by injection of goldthioglucose.

2. Continuous recordings of food and water intake showed that the obese mice ate less frequently but much larger average amounts of food compared to the control animals.

3. It is suggested that because of damage to structures in the ventro‐medial parts of the hypothalamus in the obese mice, these animals are more dependent on the peripheral mechanisms regulating food intake, such as that referable to the gastrointestinal tract.

4. The obese mice were not able to compensate with increased food intake when kaolin as caloric inert material was added to the diet.

5. The control animals compensated for kaolin added to the diet by increasing the meal frequency or the amount of food eaten each time or by a combination of both.

6. The obese mice showed little ability to increase their food intake when forced to exercise or when exhibiting a progressively increasing “spontaneous” activity.

7. Continuous recordings of water consumption showed that no damage to the mechanisms regulating water intake was incurred in this type of obesity.
Secondary Fall in Blood Pressure Following Noradrenaline Infusion in the Cat
Authors: DUNER H. , von EULER U. S.
Published: December 2008

The rise in blood pressure caused by an infusion of noradrenaline in the cat is frequently followed by a marked fall in blood pressure to subnormal levels, often lasting for 20–40 minutes.

The sensitivity to single injections of noradrenaline is diminished during the first part of this period. After section of the buffer nerves the fall after noradrenaline infusion is prolonged and often enhanced.

Intravenous infusions of calcium chloride reduce the blood pressure fall after noradrenaline.

Only a brief and moderate fall is seen in animals having received TEAB in transmission blocking doses. This fall can be abolished by small doses of ergotamine.

It is concluded that the fall in blood pressure after noradrenaline is partly due to a blocking effect on transmission within the vasomotor system.

Certain implications of the present observations for the therapeutic use of noradrenaline infusions in man are briefly discussed.
Unsaturated Fatty Acid Composition of Subcutaneous Fat in Rats in Relation to Diet
Authors: CHRISTENSEN FREDE , DAM HENFIK , ENGEL P. FREDERIK
Published: December 2008

The subcutaneous fat from three male rats reared on a fat‐free diet and three other male rats reared on a diet containing 28 % hydrogenated peanut oil was analyzed at regular intervals for linoleic acid and conjugated dienoic acid. The content of linoleic acid declined rapidly to a low level in both groups. The level of conjugated dienoic acid was almost constant in rats on the fat free diet, but increased to a maximum value of about 2 % in the fat of the rats receiving the hydrogenated peanut oil diet. The hydrogenated peanut oil contained less than 0.1 % conjugated dienoic acid. Thus a certain accumulation of the conjugated acid from this oil has taken place in the adipose tissue. The period in which the subcutaneous fat contains an increased amount of conjugated dienoic acid coincides with the period of growth retardation. The significance of this finding is discussed.
Studies on the Placental Transfer of Phosphate in the Guinea Pig.: I. The Transfer from Mother to Foetus
Authors: FUCHS FRITZ , FUCHS ANNA‐RIITTA
Published: December 2008

In a study of the placental transfer of phosphorus in the guinea pig the transfer of inorganic phosphate from mother to foetus has been investigated from the 29th day to term with the aid of radioactive phosphorus. The inorganic phosphate in the maternal plasma was found to be the main source of phosphorus to the foetus. If most of the placental uptake of phosphate not needed in placental growth was considered to be transferred to the conceptus, enough inorganic phosphate is supplied to cover the foetal needs for phosphorus. hut the safety margin is small. especially late in gestation.

The amount of phosphorus retained in foetal growth per day increases with advancing gestation. and the increase is linear from the 38th day to term. The amount retained in placental growth is nearly constant. during the period studied.

If the maternal plasma, as our previous studies indicate, contains a labile, non‐diffusible phosphorus compound. which is broken down to inorganic phosphate in the course of the chemical determination. it is either present in too small quantities to influence the results, or it is utilized by the conceptuses to the same extent as the inorganic phosphate in the maternal plasma.

The foetal plasma was found to contain twice as much inorganic phosphate as the maternal plasma. The transfer of phosphate front mother to foetus thus takes place against a concentration gradient.
Studies on the Placental Transfer of Phosphate in the Guinea Pig.: II. The Transfer from Foetus to Mother
Authors: FUCHS FRITZ , FUCHS ANNA‐RIITTA
Published: December 2008

In a study of the placental transfer of phosphorus in the guniea pig the transfer of inorganic phosphate from foetus to mother has been investigated in the last part of gestation with the aid of radioactive phosphorus. The quantity transferred in this direction across the placenta is approximately 25 % of the amount which is transmitted from mother to foetus at the same stage of gestation. The amount transferred from mother to foetus is about equal to the amount retained in foetal growth plus the amount returned to the mother. The return of phosphate from foetus to mother is facilitated by the concentration gradient from the foetal to the maternal plasma.
Ventilatory Response to CO2 During Work at Normal and at Low Oxygen Tensions
Authors: ASMUSSEN ERLING , NIELSEN MARIUS
Published: December 2008

The sensitivity of the respiratory center to CO2 during muscular work at normal and at low oxygen tensions has been studied in three human subjects.

It was found that the rectilinear part of the stimulus‐response curves in normal air was displaced to the left of the resting curve and the more so the higher the work intensity. The steepness of the curves was in the majority of cases about the same. In low oxygen the stimulus‐response curves were displaced more to the left and were much steeper than for the same work intensity in normal air. The flattening of the stimulus‐response curves found at higher CO2 concentrations is assumed to be due mainly to a special depressant effect of high CO2 tensions on the respiratory center.
Heparin Monosulphuric Acid, β‐Heparin and Dog Mast Cell Tumour Heparin in Different Clotting Systems
Authors: MAGNUSSON STAFFAN , NILSSON INGA MARIE
Published: December 2008

Standard ox heparin, dog mast cell tumour heparin, heparin monosulphuric acid and β‐heparin from ox lung were compared with respect to anticoagulant effect on human, bovine and dog plasma in one‐stage prothrombin, recalcification and thrombin systems, and on whole ox blood. Different values for the anti‐coagulant activity of a certain heparin was observed when using the various assay methods, which is in conformity with the results of previous authors. In addition it was demonstrated that one and the same assay method for a certain heparin may give different results depending on the species of plasma used as clotting substrate.
The Renal Excretion of Urea
Authors: BLEGEN EINAR , LYGREN TORLEIV , VOGT AUD
Published: December 2008

Based upon works by Russian authors and upon own clearance studies the Hungarian authors Földi and Szabó in 1951 conclude that urea loading promotes tubular secretion of urea. In an attempt at reinvestigating the problem we made 18 clearance experiments in 5 dogs with altogether 87 clearance periods. Intravenous urea loads was performed in 14 experiments with 76 clearance periods. We never succeeded in raising urea clearance significantly above creatinine clearance. It is emphasized that true creatinine which shows the same values as inulin, not total chromogen determination has to be done for obtaining correct ratios.
Indirect Determination of Peripheral Blood Pressure in Mice during Light Anaesthesia
Authors: KNUDSEN PETER J.
Published: December 2008

A method is described for measuring blood pressure in mice during light ether anaesthesia. The method involved compression of the arteria plantaris pedis with air in a glass chamber under strong illumination. During release of pressure, the pressure was arrested when blood just refilled the artery. Values at this point varied between 60‐120 mm Hg in normal mice.
A Comparative Study of Prostaglandin from Human Seminal Fluid and from Prostate Gland of Sheep
Authors: ELIASSON RUNE
Published: December 2008

1. Prostaglandin extracted from human seminal fluid and from prostate gland of sheep have been compared chemically and biologically.

2. It has not been possible to distinguish the two substances by paper chromatography, thermostability or biological tests, including rabbit jejunum, rat jejunum, guinea‐pig ileum, guinea‐pig uterus, rabbit blood pressure and cat blood pressure.

This investigation has been supported by grants from the Therese and Johan Anderssons Minne, the Lars Hiertas Minne and Karolinska Institutet Stockholm.
Pyrrolidone Carboxylic Acid in Enzymatic Casein Hydrolysates
Authors: ÅQVIST STIG , WRETLIND ARVID
Published: December 2008

An investigation has been made of the “bound” glutamic acid present in an enzymatic casein hydrolysate, aminosol, and which is determined as the difference between the values obtained micro‐biologically before and after hydrolysis of the preparation with hydrochloric acid. Part of this “bound” glutamic acid is found to consist of pyrrolidone carboxylic acid.

Pyrrolidone carboxylic acid is isolated and analyzed in different casein hydrolysates, in which it is probably formed from glutamine.

The pyrrolidone carboxylic acid content of the enzymatic casein hydrolysates investigated (aminosol) lies between 4.0 and 7.7 per cent.

The quantity of pyrrolidone carboxylic acid in the enzymatic casein hydrolysates rises continuously during the 34‐day digestion period, and is probably formed from the glutamine freed during enzymatic digestion.

In addition to pyrrolidone carboxylic acid, “bound” glutamic acid is also present in other forms in the enzymatic casein hydrolysates.
The Flicker Electroretinogram of the Human Eye
Authors: HECK J.
Published: December 2008

An account is given of the human photopic flicker electroretinogram (ERG) with increasing flicker frequency, and its different phases are analyzed. With rising frequency, the amplitude initially diminishes owing to interference between the negative a‐wave and the 2nd positive off‐effect making the ERG practically diphasic. With a further increase in flicker frequency, a considerably greater amplitude of response is recorded, owing to superimposition of the off‐effect on the b‐wave. This is followed by a linear decrease in amplitude until fusion occurs. Slightly before fusion, the flicker ERG consists of an a‐wave and the 1st off‐effect.

The flicker fusion frequency is directly proportional to the logarithm of light intensity (Ferry‐Porter law) up to 90‐95 flashes/sec. With an increase in light intensity above 2,500 lux, the flicker fusion frequency once more diminishes.

The different phases in the flicker ERG are discussed. It is suggested that the splitting of the b‐wave and the off‐effect can be explained by the presence of colour components with different latency periods.
The Effect of Intracarotid Centripetal Injection of Cholinesterase Inhibitors on the Nuclear Region of the Vestibular Nerve
Authors: DIAMANT HERMAN , HEILBRONN EDITH
Published: December 2008

Using an earlier‐described technique in which a vestibular syndrome is induced by means of intracarotid, centripetal injection of tabun the writers attempt to throw light on the question of the cause of the pharmacodynamic effect of cholinesterase inhibitors in vivo. The results show a definite relation between the induced syndrome and reduced enzyme activity. In some cases where the syndrome does not occur, there is nevertheless a definite unsymmetric decrease of the cholinesterase activity in the brain with lower activity on the injected side. It is therefore impossible to establish definitely that it is the enzyme‐inhibiting effect of the cholinesterase inhibitors which causes their pharmacodynamic effect. It may as well be a specific pharmacodynamic action. The experiments further show a rapid restitution of the enzyme activity which also occurs in brain preparations kept more than 24 hours in vitro. Determination of the activity shall accordingly be carried out within this period.
The Influence of Oxygen Tension and Some Drugs on Human Placental Vessels
Authors: NYBERG RUNE , WESTIN BJÖRN
Published: December 2008

The response of human placentas to different oxygen tensions was studied in perfusion experiments using fresh human heparinized blood. Two different techniques of perfusion were used: constant pressure and constant output. The placental volume, the blood pressure near the afferent cannula and the flow rate through the placenta were recorded.

In other experiments the circular musculature of isolated placental vessels was studied. The alterations of the length of the specimen to different oxygen tensions in the blood were registered.

The tonus of the fetal placental vessels was found to be dependent on the oxygen tension of the blood. Vasoconstriction occurred when the tension was increased and vasodilatation when the oxygen tension was decreased.

The response of the fetal placental circulation to some drugs was studied by means of the constant pressure perfusion technique. These experiments confirmed the findings of previous investigators.

The oxygen consumption of the placenta was measured under constant flow. It was found to be 3.7±0.9 ml O2 per kg and minute.
Motor Hyperactivity Resulting in Diameter Decrease of Peripheral Nerves1
Authors: ANDERSSON YVONNE , EDSTRÖM JAN‐ERIK
Published: December 2008

Two groups of guinea‐pigs were subjected to intense motor training. Fibre spectra of one unimodal and one bimodal nerve were recorded after training periods of 11 and 29 days, respectively.

The data recorded show that a significant decrease in fibre diameter can be produced by hyperactivity.

The mechanisms underlying the present findings are discussed. It is suggested that the consumption of substances in the processes may be so great on intense activity that it cannot be completely compensated by synthesis, thus resulting in a decrease in fibre diameter.
Potentiation by Histaminase Inhibitors of the Effects of Histamine on the Rectal Temperature in the Unanaesthetized Guinea‐Pig
Authors: WESTLING H.
Published: December 2008

The effects of subcutaneous injections of histamine on the rectal temperature of guinea‐pigs were potentiated by amino‐guanidine and 2‐methyl‐4‐amino‐5‐methylaminopyrimidine, two histaminase inhibitors.

 The histaminase inhibitors did not increase the response of the rectal temperature to two “histamine analogues”, which have pharmacological effects resembling those of histamine. The “histamine analogues” used are resistant to histaminase in vitro.

I am grateful to dr. H. O. Schild for advice on the statistical treatment of the data. The technical assistance given by Miss M.‐B. Johansson was highly appreciated.

This investigation was aided by a grant from the Medical Faculty, University of Lund.
Electrical Potential Gradients Through Frog Skin
Authors: ENGBÆK LISE , HOSHIKO T.
Published: December 2008

The electrical potential gradients through the frog skin bathed in sulphate Ringer's were studied with microelectrodes inserted through the skin from its outer surface.

The total skin potentials ranged between 73 and 145 mV, the inside positive with reference to ground. In most instances the total skin potential was reached in two, rarely three, distinct potential jumps. Comparison with measurements of the frog skin thickness indicated that the site of the first jump is in the epidermis while the second potential jump may correspond to the junction between epidermis and corium.
Anionic Dependence of Secretion and Secretory Potentials in the Perfused Sublingual Gland.
Authors: LUNDBERG ANDERS
Published: December 2008

The sublingual gland of the cat has been found to give normal amounts of saliva in response to acetylcholine or stimulation of the chorda when perfused at 20° C with a saline containing physiological amounts of sodium and potassium and chloride and with chloride as the only anion. On intracellular recording normal secretory potentials are found over the outer membrane with activation.

After replacement of chloride by nitrate in the perfusion fluid the amount of saliva in response to acetylcholine drops to 10–25 per cent of normal and the secretory potential over the outer gland cell membrane is greatly reduced. On readmission of chloride, secretion and the secretory potentials recover promptly. With partial substitution of chloride by nitrate, secretion is about 50 per cent at 10 per cent chloride and virtually normal at 50 per cent chloride.

It is concluded i) that the decrease of secretion and secretory potential in the nitrate‐perfused gland is due to the lack of chloride ion in the external medium of the cells; ii) that normal secretion of salt and water is largely caused by an active transport of chloride over the outer gland cell membrane.

Of other anions tested with regard to their capacity to maintain secretion bromide was found to substitute fully for chloride and iodide and thiocyanate in about the same degree as nitrate. The possibility is discussed that the activated outer membrane has a limited ability for transport of these latter ions.

On perfusion with potassium‐free saline, secretion is greatly reduced. This finding is discussed in the light of the fact that in other tissues the transport of sodium and potassium is linked.
Heat Regulation and Metabolism in some Tropical Mammals and Birds.
Authors: ENGER PER STOCKFLETH
Published: December 2008

Five species of tropical mammals and three species of high soaring birds in Panama have been subjected to various air temperatures and their heat production was determined by the carbon dioxide production. The mouse and the squirrel were good thermoregulators with a critical temperature of about 27° C, whereas the opossum, armadillo and three‐toed sloth were bad regulators. The birds have relatively low critical temperatures, about 24° (vultures) and 20° C (frigate‐bird), which may reflect their habit of soaring in cool air at high altitudes. At sub‐critical temperatures the metabolism in both mammals and birds increased with decreasing temperatures, more or less closely approaching Newton's law of cooling.

The resting metabolic rates in mouse, squirrel and opossum were in accordance with the standard mouse to elephant curve. Mammals of the suborder Xenarthra (anteater, sloth, armadillo) and the three bird species had a relatively low metabolic rate.
Recorder for Blood‐Flow Determination.
Authors: WRETLIND ARVID
Published: December 2008

An apparatus is described for direct, exact determination of the blood flow in large arteries of anesthetized animals. It permits direct recording on the kymograph curve of the blood flow per time unit (0.5 ‐ 2 sec).
Convergence of Tactile, Thermal, and Gustatory Impulses on Single Cortical Cells.
Authors: LANDGKREN SVEN
Published: December 2008

Using the extracellular microelectrode technique 325 cortical cells in the tongue projection area were studied and tested by the application of mechanical, thermal, gustatory or electrical stimuli to the tongue. Out of this group of tested cells 101 cells responded to tongue stimulation. The majority of these responding cells were discharged by one type of stimulus only, but 27 cells were activated by fibres subserving different sensory modalities. The usually observed combinations of effective stimuli were cooling and touch or cooling and “stretch”, but cortical cells responding to taste and touch or taste and “stretch” were also found. In some cells even more complicated combinations of effective stimuli were observed.

All cortical cells of the type responding to more than one modality were discharged via rapidly conducting afferent paths from touch or stretch receptors in the tongue. Thermal and gustatory stimuli on the other hand, activated these same cells more efficiently but with a longer latency (100–500 msec.) than did mechanical stimulation.

It was concluded that the observed convergence of tactile, thermal and gustatory impulses occurred in the central nervous system.
On the Extent of Hydrolysis of Triglyceride Ester Bonds in the Lumen of Human Small Intestine during Digestion.
Authors: BORGSTRÖM BENGT , TRYDING NILS , WESTÖÖ GUNNEL
Published: December 2008

Glycerides containing a fraction of a percentage of 2,2‐dimethyl[1‐14C] long‐chain fatty acids, the ester bonds of which are resistent to the action of pancreatic lipase, have been fed to human subjects.

From the concentration of the labelled acid in the neutral fat of the intestinal contents it is possible to calculate the real extent of hydrolysis of the glyceride esters fed if it is assumed that the different glycerides are absorbed at the same rate.

The results show that as a mean around sixty per cent of fed glyceride ester bonds are split in the lumen of the small intestine before absorption. About forty per cent of the fed triglycerides are completely hydrolyzed to glycerol and fatty acids, the remaining sixty per cent are partly hydrolyzed to an extent of around forty per cent, giving rise to a mixture of tri‐, di‐ and monoglycerides and free fatty acids.

It is, therefore, clear that fatty acids fed to human subjects in the form of triglycerides are absorbed from the small intestine to a greater extent as free fatty acids than as glycerides.

We are indebted to Prof. S. Bergström for placing the 13C‐labelled glycerides at our disposal.

The technical assistance of Mrs. M. B. Nilsvik and Miss K. Sjöström is gratefully acknowledged. The investigation has been supported by grants from Statens Medicinska Forsk‐ningsråd, from Knut och Alice Wallenbergs Stiftelse, from the Medical Faculty of the University of Lund and from Statens naturvetenskapliga forskningsråd.
A Modification of the Thiocholine Method for the Determination of Cholinesterase. II. Histochemical Application.
Authors: HOLMSTEDT BO
Published: December 2008

Based upon the biochemical controls of the thiocholine method (Holmstedt1957) the various steps of the histochemical procedure have been investigated. The inhibitors Mipafox and BW 284c51 and the substrates acetylthiocholine and butyrylthiocholine were combined as shown in Table 3 with the object of producing a reliable method of separating the two types of cholin‐esterase. Sufficient controls are included in the table to allow a distinct separation of the two types of cholinesterase.

The technique of the modified thiocholine method is given in detail. The following modifications have been made.

1. Inclusion of new inhibitors as above. (Mipafox and BW 284c51.)

2. No presaturation with copper thiocholine.

3. No development with ammonium sulphide.

With the modified method, stellate ganglion, striated muscle and stomach wall have been stained in order to produce confirmation of the biochemical controls, not with the purpose of studying the morphology in detail. Comparison of sympathetic ganglia and motor end‐plates shows that the ganglion cells contain only acetylcholinesterase but that the motor end‐plates also contain a considerable amount of butyrylcholinesterase.

The reasons for the alterations of the original thiocholine method are discussed. The exclusion of the presaturation with copper thiocholine produces no effect on the staining of tissue sections. The exclusion of development with ammonium sulphide diminishes diffusion artefacts to a considerable degree. Only fresh frozen sections can be used at present, if the purpose is to distinguish between the two types of cholinesterase.
Food Preferences in Obesity Caused by Goldthioglucose.
Authors: LARSSON S.
Published: December 2008

The preference for different diets has been studied in adult mice, both normal and those made obese by a single injection of goldthioglucose.

The normal mice did not show any changes in weight when transferred from standard to free selection diets. On free selection the caloric intake of fat and carbohydrate was about equal.

The obese mice showed marked variations in weight gain and food preferences. While gaining weight no carbohydrate was eaten in most cases.

In some cases obesity did not develop on the standard diet but only on the free selection diet.
Effect of Anastomosis Between the Hypoglossal and Chord a‐Lingual Nerves on the Supersensitivity of the Denervated Submaxillary Gland.
Authors: EMMELTN N. , MUREN A. , STROMBLAD R.
Published: December 2008

The central stump of the hypoglossal nerve was connected to the peripheral stump of the chorda‐lingual nerve in cats, and the effect of this operation on the sensitivity of the submaxillary gland towards adrenaline was studied.

The supersensitivity caused by the denervation of the gland was in these cases not found to remain on its high level but started to decrease after five to six weeks. When the hypoglossal nerve was stimulated electrically later on in an acute experiment the effects typical of stimulation of the chorda tympani ensued: secretion from the submaxillary and sublingual glands, which was abolished by atropine; and a vasodilatation in the submaxillary gland, which persisted after injection of atropine. Hexamethonium was remarkably efficient in abolishing these effects of hypoglossal stimulation.

It is concluded that the fall in sensitivity was due to reinnervation of the gland from the hypoglossal nerve, indicating that the restraining influence on the sensitivity, which seems to be a function of the normal efferent nerve, is not specific to this nerve but can be exerted by other nerve fibres as well. In this particular case the effect of the parasympathetic secretory fibres was taken over by somatomotor fibres meant for the tongue.
Effect of Anastomosis Between the Hypoglossal find Sympathetic Nerves on the Supersensitivity of the Denervated Submaxillary Gland.
Authors: EMMELIN N. , MUREN A. , STROMBLAD R.
Published: December 2008

Cross nerve anastomosis was performed between the proximal end of the hypoglossal nerve and the distal end of the cervical sympathetic trunk in cats. At the same time the chorda‐lingual nerve was cut. In some of the cats the supersensitivity of the submaxillary gland towards adrenaline, which follows this latter operation, was not maintained. The sensitivity started to decrease and at about the same time signs of reinnervation of the pupillary dilator and nictitating membrane from the hypoglossal nerve appeared. In acute experiments stimulation of the hypoglossus was then found to cause effects, characteristic of stimulation of the sympathetic trunk: secretion from the submaxillary gland (and sometimes from the sublingual and parotid glands as well); these responses were abolished by dihydroergotamine but not by atropine; vasoconstriction occurred in the gland; the pupil dilated and the nictitating membrane was withdrawn.

It is inferred that the hypoglossal nerve had reinnervated the superior cervical ganglion, and that impulses from the nuclei of the XIIth cranial nerve had reached the salivary gland cells via the hypoglossal and postganglionic sympathetic fibres; and that such impulses had lowered the high level of sensitivity created by section of the chorda. The observations seem to lend further support to the opinion that the gland cells innervated by sympathetic fibres have a parasympathetic nerve supply as well.
Chromatographic Separation of Five Vitamin A1 Isomers from the Eyes of Deep‐Water Prawns (Pandalus Borealis).
Authors: BARNHOLDT B. , HJARDE WILLY
Published: December 2008

In fractional chromatography of the unsaponifiable fraction from the eyes of deep water prawns the vitamin A1 present was found to separate into five components: a, b, c, d, and e. In two instances the relative proportions of the different isomers present, expressed by E325 measured on the collected fractions were found by chromatography to be as follows:

1. a:b:c:e = 0.8:52:9:38 (d was incompletely separated from c and e, the quantity of d may be estimated to be about 0.5—1 %).

2. a:b:c:d:e = 1.5:49:17:1.5:31.

The results obtained suggest that substances a, b, c, and e are identical with 11.13‐di‐cis, 11‐mono‐cis, 13‐mono‐cis and all‐trans vitamin A1. respectively, while the small quantities of substance d available have rendered the identification of this substance less certain. The possibility that substance d is 9,13‐di‐cis vitamin A1 is discussed. In a preparation marketed by Messrs. Hoffmann‐La Roche & Co., Basle, under the name of “Vitamin A, Feed Grade”, the presence has been ascertained of an isomer the properties of which agree with those of substance a and 11,13‐di‐cis vitamin A1.

The substances obtained were subjected to a number of identification tests: isomerization with iodine as catalyst, formation of anhydro vitamin by means of hydrogen chloride, determination of E620.,mμ Carr‐Price/En. v. max. and the maleic anhydride reaction. The spectrophotometry properties of the substances have also been examined for the purpose of establishing their identity.
Ventilatory Studies of the Lungs During Continuous Pressure Breathing.
Authors: HARBOE M. , LORENTZEN F. VOGT
Published: December 2008

The nitrogen clearance of the lungs during oxygen breathing has been investigated by means of the nitrogen meter during continuous pressure breathing, compared with normal conditions.

In all, 135 experiments have been made on 5 healthy subjects. The degree of uneven ventilation, nitrogen washout time, nitrogen washout volume and lung clearance index have been investigated.

Increasing tidal volumes gave more even ventilation on some subjects but no change on others.

Nitrogen clearance pattern remains stable with CPB and normal respiration.

The changes in ventilation‐perfusion relationship when switching to CPB can probably — when the ventilation does not undergo any important change — be attributed to change in blood perfusion of the lungs during CPB.