bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaporative water loss in the new‐born baby
Authors: Hey E. N. , Katz G. 
Published: December 2014

1. Measurements of total evaporative water loss (EWL) were made on sixty‐three premature and full‐term babies 0‐65 days after birth within a closed Perspex chamber under varied environmental conditions by measuring the flow and absolute humidity of air entering and leaving the chamber. Control experiments suggested that the method underestimated loss by about 5%. Measurements of O2 consumption were made concurrently by recording the volume change of the closed gas circuit.2. The total basal EWL averaged 10·8 g H2O/m2.hr in infants 2‐10 days old when ambient water vapour pressure (PH2O) was 18 mm Hg; basal EWL was correlated with basal metabolic rate at all ages studied and evaporative heat loss accounted for ∼ 23% of basal heat production.3. Respiratory water loss was measured by detecting the water added to air at 33° C passed across the face of eight infants in a trunk plethysmograph. Respiratory water loss was inversely related to the water vapour content of the inspired air; gas appeared to leave the nose ∼ 95% sat. at 35·6° C.4. Measurements of total EWL were obtained when humidity was varied and skin loss was calculated by subtracting estimated respiratory loss from total loss; changing PH2O from 7 to 25 mm Hg appeared to decrease basal skin water loss by only 1·5 g/m2.hr.5. No consistent changes in EWL were obtained when environmental temperature (TE) was varied between 28 and 34° C. Active sweating occurred in infants 0‐10 days old born within 3 weeks of term when TE exceeded 34‐35° C and rectal temperature (TR) rose above 37·2° C. The threshold rectal temperature at which sweating was detected fell significantly in the first 10 days of life; EWL increased two to fourfold when TR rose to between 37·5 and 37·8° C.6. In infants of less than 215 days post‐conceptual age (term ∼ 268 days) EWL increased less than 50% at TR 37·7‐37·8° C; it is concluded that the sweating mechanism is defective in these infants.
Biophysical and mechanical properties of red and white muscle fibres in fish
Authors: Hidaka T. , Toida N. 
Published: December 2014

1. The electrical properties of red muscle fibres of the silver carp (Carassius auratus (Linné)) were investigated and compared with those of white fibres. The resting membrane potential of red muscle was −73·1 mV, and of white muscle −82·4 mV. The effective resistance of fibre, time constant and space constant were 1·43 MΩ, 26·6 msec and 2·1 mm for red muscle and 1·0 MΩ, 48·4 msec and 1·9 mm for white muscle.2. The membrane capacitance in red muscle was 2·55 μF/cm2 and in white muscle was 7·23 μF/cm2, though the sarcoplasmic reticulum and the transverse tubular system were developed equally in both tissues.3. No rectification could be observed in the current—voltage relation in both the muscles. However, in excess potassium solutions, both types of muscle showed anomalous rectification.4. In red muscle it was rare to trigger a spike by nerve stimulation or by field stimulation of the tissue. However, in white muscle, there appeared graded responses and occasionally spikes were generated with overshoot potentials.5. Excess potassium concentration produced contracture in the red muscle, but even forty times of normal potassium never produced contracture in the white muscle.
Changes in contractile properties of disused soleus muscles
Authors: Fischbach Gerald D. , Robbins Norman 
Published: December 2014

1. The hypothesis that the pattern of activity of muscle can determine its contractile properties was tested in the case of the rat soleus subjected to chronic disuse.2. In order to characterize the pattern of motor activity over long periods of time, a method of chronic EMG recording with indwelling electrodes was developed. Some characteristics of the EMG recorded from unrestrained animals are described.3. Immobilization of the knee and ankle joints reduced aggregate EMG activity in the soleus to 5‐15% of control and resulted in a shift from tonic to a more phasic pattern of firing.4. After 4 weeks of immobilization, speeding of the soleus mechanical properties was indicated by: shortened contraction time; decreased tetanus/twitch ratio; increased maximum rate of development of tetanic tension; and decreased fusion during a 5/sec tetanus.5. Because the contractile properties of the soleus can be altered by a period of disuse with no change in innervation, neuronal control of the contractile mechanism depends in part on impulse activity.
Sodium influxes in internally perfused squid giant axon during voltage clamp
Authors: Atwater I. , Bezanilla F. , Rojas E. 
Published: December 2014

1. An experimental method for measuring ionic influxes during voltage clamp in the giant axon of Dosidicus is described; the technique combines intracellular perfusion with a method for controlling membrane potential.2. Sodium influx determinations were carried out while applying rectangular pulses of membrane depolarization. The ratio ‘measured sodium influx/computed ionic flux during the early current’ is 0·92 ± 0·12.3. Plots of measured sodium influx and computed ionic flux during the early current against membrane potential are very similar. There was evidence that the membrane potential at which the sodium influx vanishes is the potential at which the early current reverses.
The regularity of primary and secondary muscle spindle afferent discharges
Authors: Matthews P. B. C. , Stein R. B. 
Published: December 2014

1. The patterns of nerve impulses in the afferent fibres from muscle spindles have been studied using the soleus muscle of the decerebrate cat. Impulses from up to five single units were recorded simultaneously on magnetic tape, while the muscle was stretched to a series of different lengths. Various statistics were later determined by computer analysis.2. After the ventral roots were cut to eliminate any motor outflow to the muscle spindles, both primary and secondary spindle endings discharged very regularly. At frequencies around 30 impulses/sec the coefficient of variation of the interspike interval distributions had a mean value of only 0·02 for the secondary endings and 0·058 for the primary endings. The values obtained for the two kinds of ending did not overlap.3. When the ventral roots were intact, the ‘spontaneous’ fusimotor activity considerably increased the variability of both kinds of endings. Secondary endings still discharged much more regularly than primary endings, even when the fusimotor activity increased the frequency of firing equally for the two kinds of endings. At frequencies around 30/sec the average coefficient of variation of the interval distributions was then 0·064 for the secondary endings and 0·25 for the primary endings.4. When the ventral roots were intact there was usually an inverse relation between the values of successive interspike intervals. The first serial correlation coefficient often had values down to — 0·6 for both kinds of ending. Higher order serial correlation coefficients were also computed.5. Approximate calculations, based on the variability observed when the ventral roots were intact, suggested that when the length of the muscle was constant an observer analysing a 1 sec period of discharge from a single primary ending would only be able to distinguish about six different lengths of the muscle. The corresponding figure for a secondary ending was twenty‐five lengths.6. The increase in variability with fusimotor activity, and the pattern of serial correlations, were probably caused by static fusimotor fibres firing at rates below the fusion frequency of the intrafusal muscle fibres that they supply.
Osmotic concentration of the gastric juice of dogs
Authors: Altamirano M. , Izaguirre Elizabeth , Milgram E. 
Published: December 2014

1. The freezing point of the gastric juice, produced by histamine stimulation in anaesthetized dogs, of the arterial plasma and of the plasma obtained from a gastric vein were measured.2. The osmolality of the blood that passes through the gastric mucosa increases during secretion of acid juice.3. The amount of water that should be removed from the arterial plasma to obtain a solution isosmolal to the gastric venous plasma is equivalent to the amount of water required to dilute the secreted H+. From this result it is concluded that the increase of osmolality of the venous plasma is a consequence of the clearance of water free of solute by the gastric mucosa.4. The gastric juice was hyposmotic to the venous plasma in twenty out of thirty dogs, being isosmotic to that plasma in seven dogs. Even in the last group of animals, the gastric secretion might be considered as slightly hypotonic to the venous blood that passes through the secretory part of the mucosa.5. Considerations based on available data suggest that the ‘primary’ acid juice is usually hyposmotic to the extracellular fluid in the vicinity of the oxyntic cells.
Rod increment thresholds on steady and flashed backgrounds
Authors: Hallett P. E. 
Published: December 2014

1. This paper presents increment threshold data for a fairly wide range of parameters but certain of the relationships are slightly complicated by what may amount to large differences in the observers’ criterion. The following paper deals with a very limited range of parameters but the measurements are more precise and the analysis more simple.2. Increment thresholds have been measured for a small, brief duration test viewed against large steady and pulsed backgrounds, using the technique of Aguilar & Stiles (1954) which is intended to isolate rod vision. Under these circumstances it is shown that the test is seen by the rods and that the cones do not disturb the sensitivity of the rods.3. The relative positions of increment threshold curves for steady and pulsed backgrounds are usually consistent with an integration time of τ = ca. 0·1 sec.4. Backgrounds of less than 0·1 sec duration are effectively impulse inputs in the sense that the magnitude and time course of the test threshold disturbance (‘impulse function’) is dependent only on background energy.5. Functions of the impulse function may be substituted for the classical integration time τ. The exact form of the impulse function and its theoretical treatment is pursued in the next paper.6. The threshold disturbance caused by switching on a background light settles to a steady value within 2 to 3 times τ.
Maternal placental and myometrial blood flow in the pregnant rabbit
Authors: Duncan Sheila L. B. , Lewis B. V. 
Published: December 2014

1. In anaesthetized rabbits 27–29 days pregnant (term is 31 days) uterine blood flow was measured in an extracorporeal loop between a carotid and the central end of an external iliac artery, the descending aorta and its other branches being tied. Mean flow was 45 ± 2 ml. min−1, or 105 ± 4 ml. min−1 per kg uterus and contents in thirty‐four litters.2. The partition of uterine blood flow to placentas (∼ 60%), myometrium (∼ 27%) and vagina (∼ 13%) as estimated by injection of isotopelabelled microspheres of 35 or 50 μ diameter, was similar in intact rabbits and in those with an extracorporeal loop.3. Maternal blood flow was greater to the placentas of larger foetuses both absolutely and per unit placental weight. Flow to the placentas of dead foetuses was much less than to those of live foetuses, but flow to the adjacent myometrium was not decreased.4. Maternal hypoxaemia (Pa, O2 ∼ 40 mm Hg) caused vasoconstriction in the uterine vascular bed after 3‐4 min. The distribution of blood flow within the uterus was altered, the placental fraction falling to 32%. This was unaffected by carotid denervation.5. These observations suggest that there are large differences in the physiological control of maternal blood flow to the placenta, myometrium and vagina.
Control of body temperature in the unanaesthetized monkey by cholinergic and aminergic systems in the hypothalamus
Authors: Myers R. D. , Yaksh T. L. 
Published: December 2014

1. In the unanaesthetized rhesus monkey, 5‐hydroxytryptamine (5‐HT), catecholamines, acetylcholine or carbachol were micro‐injected in a volume of 1·0 μl. or less through chronically implanted cannulae at eighty‐six sites in the hypothalamus.2. 5‐HT in doses of 2‐10 μg caused a long‐lasting elevation in temperature which was dose‐dependent. An anatomical ‘mapping’ of the hypothalamus revealed that the hyperthermic action of 5‐HT was localized to the anterior, pre‐optic area directly ventral to the anterior commissure.3. Noradrenaline in doses of 1‐12 μg produced a dose‐dependent fall in temperature of short duration. An anatomical ‘mapping’ showed that the hypothermic action of this and other catecholamines was again localized to the anterior, pre‐optic region.4. Acetylcholine, alone or in a mixture with eserine, or carbachol caused a dose‐dependent hyperthermia which was characterized by an intense rise of short duration and vigorous shivering. A ‘mapping’ of this response revealed a diffuse patterning of sites throughout the hypothalamus which were sensitive to the application of acetylcholine and carbachol. However, in one circumscribed region at the junction between the posterior hypothalamus and mesencephalon, the two cholinomimetic substances caused a marked fall in temperature.5. We conclude that 5‐HT activates a cholinergic heat production pathway which projects from the anterior to posterior hypothalamus. Noradrenaline, on the other hand, blocks the hyperthermic action of 5‐HT rather than activates the heat loss system. A chemically mediated heat loss pathway apparently does not exist in the hypothalamus.
The role of glandular activity in the electrical response of amphibian skin to noradrenaline
Authors: House C. R. 
Published: December 2014

1. The electrical response of isolated amphibian skins to the presence of 4 × 10−5
M noradrenaline in the inner medium has been studied.2. The response to noradrenaline consists of a transient secretion from the skin glands, a transient increase in the short‐circuit current, a transient decrease in the skin resistance and a partial depolarization of the skin potential (inside surface becoming less positive) followed by a hyperpolarization.3. The origin of the initial depolarizing phase of the response to noradrenaline has been studied.4. It is considered that the initial depolarization results partially from an increase in the chloride permeability of the outer membranes of the epithelial cells and predominantly from the emergence of an additional transient shunt pathway in the skin.5. It is proposed that during secretory activity the skin glands constitute the transient shunt pathway responsible for the initial depolarizing phase of the response to noradrenaline.
Intracellular recordings from ganglia of the thoracic sympathetic chain of the guinea‐pig
Authors: Blackman J. G. , Purves R. D. 
Published: December 2014

1. Intracellular recordings have been obtained from cells of thoracic paravertebral sympathetic ganglia of guinea‐pigs.2. Resting potentials were 50–70 mV. The steady‐state current—voltage curve was linear for all hyperpolarizations and usually for depolarizations up to 10 mV. The slope of this curve was 19–186 MΩ (mean 55 MΩ). Time constants of cells were 6–14 msec (mean 9·1 msec).3. Most cells maintained a high rate of firing of action potentials during strong current pulses.4. Indirect stimulation via the rami communicantes or the interganglionic nerves of the sympathetic chain evoked a graded synaptic response which could lead to the discharge of one or more action potentials. Hexamethonium blocked the responses to such stimulation. Occasionally an all‐or‐none response remained, apparently conducted antidromically along the cell's axon.5. Spontaneous synaptic potentials were observed. Their occurrence frequency was increased during indirect stimulation. If they are assumed to represent single quanta of release of transmitter, the quantal content of a threshold synaptic potential was 8–20 quanta.6. Preganglionic fibres could ascend at least three segments or descend two after entering the sympathetic chain. They had conduction velocities of 0·1–1·1 m/sec.7. Inexcitable cells were frequently impaled. Repetitive indirect stimulation gave rise in these cells to a large (20 mV) slow depolarizing response.
The spatial selectivity of the visual cells of the cat
Authors: Campbell F. W. , Cooper G. F. , Enroth-Cugell Christina 
Published: December 2014

1. Micro‐electrode recordings have been made from single units in the visual cortex of the cat, during stimulation by moving grating patterns generated on a cathode ray tube.2. The responses of the units have been measured in terms of either the frequency of impulses, or the contrast sensitivity, and expressed as a function of the spatial frequency of the grating pattern.3. The amplitude of the responses recorded from cortical cell bodies was dependent upon the orientation of the moving grating, and for these units the stimulus was always presented at the preferred orientation. The response amplitude of other units did not depend upon the orientation of the grating stimulus, and these are believed to be the terminations of geniculate fibres.4. The high spatial frequency end of the response function measured in terms of the contrast sensitivity could be well fitted by an exponential function. Subtraction of the blank count from the impulse frequency data gave a curve fitted by the same exponential function. The low frequency end was less consistent.5. The spatial frequency at which this exponential function had fallen by one log. unit was taken to specify the position of the unit's response in the spatial frequency spectrum. For all units these values cover a range of four octaves of spatial frequency (from 0·18 to 3·8 cycles per degree).6. It is suggested that these neurophysiological results support psychophysical evidence for the existence in the visual system of channels, each selectively sensitive to a narrow band of spatial frequencies.
Activity of lung irritant receptors in pulmonary micro‐embolism, anaphylaxis and drug‐induced bronchoconstrictions
Authors: Mills Janet E. , Sellick Hilary , Widdicombe J. G. 
Published: December 2014

1. Lung irritant receptors have been studied in rabbits by recording action potentials from single vagal nerve fibres. Some of the rabbits were bilaterally vagotomized, and some paralysed and artificially ventilated.2. The receptors gave rapidly adapting irregular discharges on inflation and deflation of the lungs. Many were stimulated by insufflation of ammonia vapour into the lungs, and some by passage of a fine catheter into the right bronchial tree. The fibres had conduction velocities in the range 3·6–25·8 m/sec.3. The receptors were strongly stimulated by intravenous injections of histamine acid phosphate, 25–100 μg/kg. The response was considerably reduced by previous injection of isoprenaline which also reduced the bronchoconstriction due to histamine.4. The receptors were stimulated by intravenous injections of isoprenaline, phenyl diguanide and micro‐emboli, and by anaphylaxis induced in rabbits previously sensitized to egg albumin.5. The receptor responses could not be closely correlated in size with simultaneous changes in total lung resistance, lung compliance, tidal volume or breathing frequency.6. It is concluded that, in rabbits with intact vagus nerves, lung irritant receptors contribute to the reflex hyperpnoea and bronchoconstriction of the conditions studied.
Effect of barbiturates on ‘quantal’ synaptic transmission in spinal motoneurones
Authors: Weakly J. N. 
Published: December 2014

1. Monosynaptic excitatory post‐synaptic potentials (EPSPs) produced in triceps surae motoneurones of the cat by stimulation of single afferent fibres in the muscle nerve were recorded with intracellular electrodes before and after the administration of thiopentone or pentobarbitone.2. The average amplitude of the ‘unit’ EPSP was 0·11–0·21 mV and remained unchanged after the administration of the barbiturates (10 mg/kg,
I.V.).3. Mean quantum content (m) ranged from 1·9 to more than 5 before drug administration. The m was reduced by thiopentone (10 mg/kg,
I.V.) and pentobarbitone (10 mg/kg,
I.V.) by 23·1 and 24·7% respectively.4. The barbiturates, in the doses employed, produced no alterations in the input resistance of the motoneurone membrane or in the strength—duration relation obtained by passing depolarizing current pulses through the micro‐electrode.5. It is concluded that the action of thiopentone and pentobarbitone, in the doses used, is confined to the presynaptic nerve terminals and results in a reduction in the amount of transmitter released by afferent impulses.
A circadian rhythm in the disappearance of thyroxine from the blood in the calf and the thyroidectomized rat
Authors: Nathanielsz P. W. 
Published: December 2014

1. Many factors affect the rate of disappearance of thyroxine from the peripheral blood. The normal animal is exposed to these to differing extents throughout a 24‐hr day. Conflicting results have been described with regard to circadian variations in several parameters of thyroid physiology.2. The disappearance of radioactive thyroxine from the blood has been followed in intact and thyroidectomized calves and thyroidectomized rats fed either at night or during the day.3. When calves were fed during the day the rate of disappearance of thyroxine from the blood was significantly faster in the day than at night. When fed at night the nocturnal disappearance rate became faster than the diurnal rate.4. The circadian rhythm persists in the thyroidectomized calf and is hence not solely a feature of hypothalamic, pituitary or thyroid function.5. On a full diet (Oxo Ltd., diet 41 B) the faster disappearance of thyroxine from the blood occurs at night when rats feed at night and during the day when they feed during the day.6. After bile‐duct ligation the faster disappearance still occurs in the period in which the animal is feeding. This occurs even if the diet is solely glucose. When feeding on pure glucose the effect is less marked.7. The substitution of a glucose diet for a full oxoid diet (Oxo Ltd., diet 41 B) results in a fall of 33·5% in the over‐all disappearance rate in bile‐duct‐ligated animals.8. These results show that feeding, and the processes associated with it, are important factors determining utilization of thyroxine. This is so even after the prevention of any biliary‐faecal loss of thyroxine.
Warm receptors in the nasal region of cats
Authors: Hensel H. , Kenshalo D. R. 
Published: December 2014

1. Specific warm receptors in the nasal region of cats were studied by recording afferent impulses from single units dissected from the infraorbital nerve. In addition, a few cold fibres from the same region were examined.2. Numerous warm fibres with spot‐like receptive fields were found on the back of the nose. They were not excited by mechanical stimulation.3. Multi‐fibre strands serving this area responded to moderate warming with an increase of the integrated discharge.4. At constant temperatures from 30° C on, single warm fibres showed a steady discharge with a regular sequence of impulses, the frequency of which rose steeply with temperature and reached a maximum between 45 and 47° C. At higher temperatures the frequency fell to zero.5. Rapid warming caused a dynamic overshoot, rapid cooling a transient inhibition of the warm fibre discharge. The highest dynamic frequencies of single fibres were 200 impulses/sec.6. For a large population of single warm fibres the average maximum of static activity was 36 impulses/sec at 46° C, whereas the cold fibre population had a maximum of 9 impulses/sec at 27° C.