bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flash bleaching of rhodopsin in the human retina
Authors: Ripps H. , Weale R. A. 
Published: December 2014

1. Measurements were made of the photo‐sensitivity of rhodopsin in the living human retina following bleaching with (a) a flash less than 1 msec in duration, (b) a continuous exposure lasting 30 sec.2. The apparatus consisted of a fundus reflectometer coupled to a computer for on‐line processing. Three subjects were studied.3. The relations between the quantity of pigment bleached and the incident energy are so similar for the flash and continuous exposure tests that the occurrence of photo‐reversal (such as has been reported in similar circumstances for visual pigment in solution) seems to be ruled out.4. Nonetheless, the two experimental conditions lead qualitatively to two different photo‐chemical states in as much as the density difference spectrum for the flash exposure is displaced toward longer wave‐lengths in comparison with the data obtained with the continuous exposure.5. The results are discussed with reference to the sequence of events following the bleaching of visual pigments solutions as reported by other workers.
The influence of calcium on sodium efflux in squid axons
Authors: Baker P. F. , Blaustein M. P. , Hodgkin A. L. , Steinhardt R. A. 
Published: December 2014

1. Previous work has shown that the sodium efflux from the axons of Loligo forbesi increases when external sodium is replaced by lithium.2. The increase in efflux in lithium was unaffected by ouabain but was abolished by removal of external calcium; in these respects it differed from the potassium‐dependent sodium efflux which was abolished by ouabain but not reduced by removal of external calcium.3. Strontium but not magnesium could replace calcium in activating the ouabain‐insensitive sodium efflux; lanthanum had an inhibitory effect.4. Replacing all the external NaCl by choline chloride or dextrose gave a rise in Na efflux which was abolished by ouabain but not by removal of external calcium.5. The rise in Na efflux resulting from partial replacement of NaCl by dextrose or choline chloride consisted of two components one of which was ouabain‐insensitive and calcium‐dependent and the other was inhibited by ouabain but calcium‐insensitive.6. The ouabain‐insensitive component of the Na efflux was activated by low concentrations of Na, Li or K but inhibited by high concentrations of Na and to a lesser extent Li. The inhibiting effect of high Na was of the kind expected if these ions displace calcium from an external site.7. The ouabain‐insensitive component of the Na efflux was abolished by cyanide, had a Q10 of 2·7; and was roughly proportional to [Na]i2. It was much more variable in magnitude than the ouabain‐sensitive, potassium‐dependent component of the sodium efflux.8. The calcium influx increased five to fortyfold when external NaCl was replaced by LiCl or dextrose, the increase for Li being larger than the increase for dextrose.9. The calcium influx from Na, Li or dextrose sea water was increased three to tenfold by increasing the internal Na about fourfold.10. The experiments provide evidence for a coupling between an inward movement of calcium and an outward movement of sodium.
Motor nerves of salivary myoepithelial cells in dogs
Authors: Emmelin N. , Garrett J. R. , Ohlin P. 
Published: December 2014

1. The pressures in the ducts of the parotid and submaxillary glands were recorded in dogs under chloralose‐urethane anaesthesia. A single stimulus applied to the parasympathetic nerve regularly caused a pressure rise of short duration. Usually it did not evoke secretion.2. In both glands a single stimulus applied to the vagosympathetic trunk usually caused a pressure response of short duration. It had no secretory effect.3. In the parotid gland, repetitive vagosympathetic stimulation caused a sustained increase of pressure in the duct, usually without inducing secretion.4. In the submaxillary gland, repetitive vagosympathetic stimulation caused a sustained pressure rise, even when the secretory response had been abolished by propranolol.5. It is concluded that the salivary myoepithelial cells of dogs are supplied with fibres from both sympathetic and parasympathetic divisions of the autonomic nervous system and both can cause the cells to contract.
Extraocular muscle afferents to the cerebellum of the cat
Authors: Fuchs A. F. , Kornhuber H. H. 
Published: December 2014

1. Afferents from the extraocular muscles to the cerebellum of the cat were investigated by evoked potential techniques using muscle stretch as a stimulus.2. Short (about 4 msec) latency responses occurred in the vermian folia anterior (Larsell's lobule V b, c) and posterior (lobules VI and VII) to the primary fissure under light Nembutal anaesthesia.3. The location of the cerebellar eye muscle responses coincides with the visual and auditory projections as well as homologous projections from cortical Areas 8 (the frontal eye fields) and 17 in the monkey. It also overlaps the oculomotor area of the cerebellum as revealed by electrical stimulation.4. Facts 2 and 3 above, together with the selective disturbance of saccadic eye movements in humans with cerebellar atrophy, suggest a cerebellum mediated proprioceptive feed‐back loop for the control of saccadic eye movements.
The molecular dimensions of porcine neurophysin and some thermodynamic parameters of the reaction with lysine vasopressin
Authors: Ginsburg M. , Thomas P. J. 
Published: December 2014

1. The molecular weight of porcine neurophysin was estimated by molecular sieve chromatography and by analytical ultracentrifugation and was found to be in the order of 13,000.2. Internal evidence for the homogeneity of the preparation of neurophysin with respect to molecular weight was obtained in the ultracentrifugation experiments.3. The frictional ratio of neurophysin was 1·1 which suggests that the molecular form of the protein approximates to a sphere.4. The molecular weight and frictional ratio were not affected by temperature change (10–34° C) or by twofold change in protein concentration.5. The binding of [14C]lysine vasopressin to porcine neurophysin was studied at 0, 27 and at 45° C, and double reciprocal plots of the binding were shown to be curvilinear at 27 and at 45° C and rectilinear at 0° C.6. Concordant estimates for maximum binding capacity were obtained by extrapolations from the data at 27 and 45° C by applying two independent empirical methods of approximation; these agreed with the estimate obtained by extrapolation of the straight line, fitting data obtained at 0° C, being approximately 1 mole lysine vasopressin per 13,000 g protein.7. The association constant and thermodynamic parameters of the reaction were estimated for near saturation conditions. The reaction is entropy driven.8. The binding of lysine vasopressin was found to be dependent on protein concentration. No dependence of oxytocin binding on protein concentration was apparent.
Calcium movements across the membrane of human red cells
Authors: Schatzmann H. J. , Vincenzi F. F. 
Published: December 2014

1. A study has been made of the cellular content and movement of Ca across the membrane of human red blood cells.2. The [Ca] in the cellular contents of fresh red cells is 4·09 × 10−2 m
M. The intracellular concentration of free ionic Ca ([Ca2+]) is considered to be less than this value and therefore less than extracellular [Ca2+] under normal conditions.3. Observation of unidirectional Ca fluxes with 45Ca confirms previous reports of low permeability of the red cell membrane for Ca. After nearly 1 week of loading in the cold, intracellular 45Ca content is 1·8% of extracellular 45Ca content. Appearance in extracellular fluid of 45Ca from coldloaded cells can be considered to arise from two compartments. Efflux of 45Ca from the ‘slower compartment’ is accelerated by the addition of glucose.4. Starved red cells, incubated at 37° C, after reversible haemolysis for loading with Ca and Mg‐ATP, exhibit an outward net transport of Ca against an electrochemical gradient. The transport is associated with the appearance of inorganic phosphate (Pi). Cells treated similarly, but without ATP show no transport and no appearance of Pi.5. During the initial phase of transport, 1·3 mole Pi appear per mole Ca transported.6. The transport of Ca from ATP‐loaded cells is highly temperature‐dependent, with a Q10 of 3·5.7. Cell membrane adenosine triphosphatase (ATPase) activity of reversibly haemolysed cells is stimulated only by intracellular, and not by extracellular Ca.8. Neither Ca transport in reversibly haemolysed cells, nor the Ca‐Mg activated ATPase of isolated cell membranes is sensitive to Na, K, ouabain or oligomycin.9. Mg is not transported under the conditions which reveal Ca transport, but Mg appears to be necessary for Ca transport.10. Sr is transported from reversibly haemolysed Mg‐ATP‐loaded cells. Sr also can substitute for Ca, but not for Mg, in the activation of membrane ATPase.11. It is concluded that, in addition to a low passive permeability, an active extrusion mechanism for Ca exists in the human red cell membrane. This extrusion mechanism, in addition to a low passive membrane permeability for Ca, may represent the means by which intracellular Ca content is maintained at a low level. It is suggested that the Ca‐Mg activated membrane ATPase and the active transport of Ca are two manifestations of the same process.
Non‐linear summation of unit synaptic potentials in spinal motoneurones of the cat
Authors: Kuno M. , Miyahara J. T. 
Published: December 2014

1. Monosynaptic excitatory post‐synaptic potentials (EPSPs) produced in spinal motoneurones of the cat by stimulation of a single afferent fibre were recorded with intracellular electrodes.2. In total, seventy‐three triceps surae motoneurones were studied with stimulation of thirty‐six different afferent fibres.3. The mean amplitude of the EPSPs evoked by single afferent impulses ranged from 0·06 to 2·0 mV with an average of 0·27 mV.4. The mean number of unit EPSPs responding to a single afferent impulse (m) was calculated from the number of failures. The values ranged from 0·7 to more than 5. About 10% of the sample showed no failure of synaptic response in about 200 consecutive trials. The m values for these synaptic responses were estimated to range from 5 to 15.5. In the majority of tests, the observed amplitude fluctuations of monosynaptic EPSPs evoked by stimulation of a single fibre were less than those expected from Poisson's law. This discrepancy may be accounted for by non‐linear summation of the unit EPSPs at dendritic synaptic sites.6. It is suggested that the synaptic responses initiated at different sites of a motoneurone may summate linearly at the soma, although summation of unit EPSPs is non‐linear at individual synaptic sites.
The nature and location of certain phasic mechanoreceptors in the cat's foot
Authors: Lynn Bruce 
Published: December 2014

1. The locations of the receptor endings of twenty‐two phasic, primary afferent units which could be excited by small (less than 40 μm) point displacements of cats' large foot pads have been determined by dissection.2. Eleven of these units had endings located within or immediately below the skin on the plantar surface of the pad; eight had endings located deep within the pad and three had endings on the digits.3. All the deep and digital endings were of the PC type of Jänig, Schmidt & Zimmermann (1968) whilst five of the superficial endings were definitely of the RA type of Jänig et al. (1968), and another five could have been. One superficial ending had properties intermediate between those of RA and PC receptors.4. It was shown by dissection that the endings of four of the PC type units were Pacinian corpuscles and such corpuscles were seen within 1 mm of the apparent location of six other PC receptors. Pacinian corpuscles were found close to only two of the eleven superficial receptor locations.5. It is therefore concluded that of the two functionally distinct types of phasic receptors studied, the PC receptors are Pacinian corpuscles located deep in the pad or on the digits, whilst the RA receptors are located within or immediately below the skin and are not Pacinian corpuscles.
Reflex discharges into thoracic white rami elicited by somatic and visceral afferent excitation
Authors: Coote J. H. , Downman C. B. B. , Weber W. V. 
Published: December 2014

1. Reflex discharges in white rami (WR) were elicited by single‐shock stimulation of dorsal roots (DR), splanchnic (SPL) and intercostal nerves (IC).2. The reflexes have been compared in anaesthetized cats with intact neuraxis, after mid‐brain transection and after high cord transection. The brain stem can maintain moderate inhibition of the WR responses, but strong inhibition of IC responses. After cord transection all reflexes are released again.3. Stimulation of ventromedial medullary reticular substance could completely, and independently, inhibit maximal SPL‐to‐WR and IC‐to‐WR reflexes.4. Carotid sinus distension did not reduce WR responses, indicating that the major part of the volley is not in vasoconstrictor fibres.5. Central delay of DR‐to‐WR responses is longer than delay of DR‐to‐IC responses and is unchanged by transections of the neuraxis at mid‐brain or high spinal levels.6. There was no facilitation of WR responses by a prior conditioning volley in the visceral or somatic afferent pathway in contrast to early facilitation of the IC responses.
A theory of cerebellar cortex
Authors: Marr David 
Published: December 2014

1. A detailed theory of cerebellar cortex is proposed whose consequence is that the cerebellum learns to perform motor skills. Two forms of input—output relation are described, both consistent with the cortical theory. One is suitable for learning movements (actions), and the other for learning to maintain posture and balance (maintenance reflexes).2. It is known that the cells of the inferior olive and the cerebellar Purkinje cells have a special one‐to‐one relationship induced by the climbing fibre input. For learning actions, it is assumed that:(a) each olivary cell responds to a cerebral instruction for an elemental movement. Any action has a defining representation in terms of elemental movements, and this representation has a neural expression as a sequence of firing patterns in the inferior olive; and(b) in the correct state of the nervous system, a Purkinje cell can initiate the elemental movement to which its corresponding olivary cell responds.3. Whenever an olivary cell fires, it sends an impulse (via the climbing fibre input) to its corresponding Purkinje cell. This Purkinje cell is also exposed (via the mossy fibre input) to information about the context in which its olivary cell fired; and it is shown how, during rehearsal of an action, each Purkinje cell can learn to recognize such contexts. Later, when the action has been learnt, occurrence of the context alone is enough to fire the Purkinje cell, which then causes the next elemental movement. The action thus progresses as it did during rehearsal.4. It is shown that an interpretation of cerebellar cortex as a structure which allows each Purkinje cell to learn a number of contexts is consistent both with the distributions of the various types of cell, and with their known excitatory or inhibitory natures. It is demonstrated that the mossy fibre‐granule cell arrangement provides the required pattern discrimination capability.5. The following predictions are made.(a) The synapses from parallel fibres to Purkinje cells are facilitated by the conjunction of presynaptic and climbing fibre (or post‐synaptic) activity.(b) No other cerebellar synapses are modifiable.(c) Golgi cells are driven by the greater of the inputs from their upper and lower dendritic fields.6. For learning maintenance reflexes, 2(a) and 2(b) are replaced by2′. Each olivary cell is stimulated by one or more receptors, all of whose activities are usually reduced by the results of stimulating the corresponding Purkinje cell.7. It is shown that if (2′) is satisfied, the circuit receptor → olivary cell → Purkinje cell → effector may be regarded as a stabilizing reflex circuit which is activated by learned mossy fibre inputs. This type of reflex has been called a learned conditional reflex, and it is shown how such reflexes can solve problems of maintaining posture and balance.8. 5(a), and either (2) or (2′) are essential to the theory: 5(b) and 5(c) are not absolutely essential, and parts of the theory could survive the disproof of either.
The response of the sweat glands of the new‐born baby to thermal stimuli and to intradermal acetylcholine
Authors: Foster K. G. , Hey E. N. , Katz G. 
Published: December 2014

1. Measurements of evaporative sweat loss were made on fifty‐six premature and full‐term babies 1‐67 days after birth with an infra‐red analyser and a ventilated capsule placed on the thigh. Measurements were also made of total evaporative water loss while in a closed metabolic chamber and of the regional distribution of sweating with starch—iodine paper.2. No sweating to thermal stimuli could be detected in infants of less than 210 days post‐conceptual age, even when rectal temperature rose as high as 37·8° C. In older infants sweat was detected first on the forehead and temple, later on the chest, and usually by 240–260 days post‐conceptual age on the legs (term ∼ 268 days). Generalized sweating on the limbs appeared at an earlier post‐conceptual age in the more prematurely born infants.3. The response of sweat glands on the thigh to an intradermal injection of 2 μg acetylcholine (ACh) was tested. No sweat response was detected in infants under 225 days post‐conceptual age, while all infants born within 2 weeks of term responded. The response was often augmented after 2‐5 tests at 5‐10 min intervals; all the eight infants born within 2 weeks of term who were examined twice in the first 2 weeks of life showed a greater response on the second occasion.4. An average of 414 active sweat glands/cm2 were detected on the thigh in eight babies 7–10 days old born within 2 weeks of term. This was 6½ times the number found in adults. The mean peak sweat rate to chemical stimulation was however only 2·4 nl./gland.min, which was 3 times lower than the maximum rate recorded in adults.5. In five infants with congenital defects of the brain and complete absence of temperature control there was no sweat response to thermal or direct chemical stimulation of the glands.6. Functional maturation appears to depend on intact central innervation and is marginally hastened by post‐natal factors. Immaturity of the sweat glands can account for the lack of any response to thermal stimuli in premature babies, but not for the modest thermal response obtained in babies at term.
The effect on drinking in the rat of intravenous infusion of angiotensin, given alone or in combination with other stimuli of thirst
Authors: Fitzsimons J. T. , Simons Barbara J. 
Published: December 2014

1. Intravenous infusion of angiotensin causes rats which are in water balance to drink water.2. The mean amount of angiotensin needed to initiate drinking was 29·1 ± 4·6 μg/kg (
S.E. of mean) in twenty normal rats, and 15·7 ± 2·1 μg/kg in thirty‐four nephrectomized rats.3. The nephrectomized rat is therefore more sensitive to this action of angiotensin than the rat with intact kidneys.4. The rates of infusion (0·05–3·0 μg/kg−1 min−1) which cause drinking are comparable to those used to produce other effects in rats.5. Angiotensin restores the drinking response of the nephrectomized rat subjected to caval ligation to a value similar to that obtained in the uninfused normal rat subjected to caval ligation.6. The effects of angiotensin and hypertonic saline on drinking are additive when both substances are administered to nephrectomized rats.7. These experiments provide further support for the view that the renin—angiotensin system is concerned in extracellular thirst.
Effect of environmental temperature on the turnover of noradrenaline in hypothalamus and other areas of rat brain
Authors: Simmonds M. A. 
Published: December 2014

1. The hypothesis that noradrenaline (NA) may be a transmitter in the temperature regulating centre in the hypothalamus is based on the changes in rectal temperature induced by injection of large doses of NA into the brain. As an alternative approach, the effect of environmental temperature on the rate of turnover of endogenous NA in the hypothalamus has been studied.2. Small amounts of tritium labelled noradrenaline [3H]NA were injected into the c.s.f. of rats in order to label radioactively the endogenous NA in the brain. The rats were then exposed to environmental temperatures of 9, 17, 24 and 32° C. The rates of disappearance of [3H]NA from discrete areas of brain were taken as indices of the rates of turnover of endogenous NA in those areas.3. The rate of disappearance of [3H]NA from the hypothalamus was three times as fast at 9 and 32° C as at 17 or 24° C. There were no such significant differences from the pre‐optic area or ‘rest of brain’ (whole brain minus hypothalamus, pre‐optic area, cerebellum and medulla).4. The endogenous concentrations of NA were not altered by the experimental procedures in any of the areas of brain studied.5. The rats maintained normal rectal temperatures at environmental temperatures of 9, 17 and 24° C but became 2·8° C hyperthermic at 32° C.6. It is concluded that mild conditions of both heat and cold resulted in an increased turnover of NA in specific nerve terminals in the hypothalamus. Since the rats were thermoregulating normally, the nerve terminals involved are regarded as forming a part of the central temperature regulating centre.
Some physiological properties of identified mammalian neuroglial cells
Authors: Dennis M. J. , Gerschenfeld H. M. 
Published: December 2014

Mammalian glial cells were identified and studied in the optic nerves of anaesthetized rats.Cells with membrane potentials of 77–85 mV were located in the optic nerve with capillary micropipettes. These were shown to be neuroglia by iontophoretic injection of a fluorescent dye through the recording electrode, followed by histological verification of the location of the dye. No distinction was made between astroglia and oligodendroglia.Neuroglial cells gave no impulse activity. Their membrane potential was studied in isolated optic nerves by varying the ionic composition of the bathing fluid. The glial membrane potential depends predominantly on a transmembrane gradient of potassium ions.
Spontaneous and evoked activity of motor nerve endings in calcium Ringer
Authors: Katz B. , Miledi R. 
Published: December 2014

1. Electrical activity of neuromuscular junctions of the frog was studied in a medium (Ca‐Ringer) whose Na ions had been entirely replaced by Ca.2. Spontaneous miniature end‐plate potentials (m.e.p.p.s) of reduced amplitude are recorded in this abnormal ionic environment, and graded end‐plate potentials can be elicited by applying depolarizing current pulses to the pre‐junctional parts of the nerve.3. Addition of 5 m
M tetraethylammonium (TEA) to the Ca‐Ringer causes the appearance, in almost all‐or‐none fashion, of very large e.p.p.s (up to 45 mV in amplitude) in response to nerve stimulation.4. These ‘giant’ e.p.p.s occur despite the curarizing action of TEA (and its depressing effect on the amplitude of m.e.p.p.s) and they persist after application of tetrodotoxin.5. After several hours exposure to Ca‐Ringer, spontaneous end‐plate activity gradually declines, and eventually evoked e.p.p. responses fail. On return to normal Na‐Ringer, spontaneous end‐plate activity is quickly resumed, but the potentials have an abnormal, very wide, amplitude distribution.6. The results are discussed, in conjunction with relevant work on the squid giant synapse, in terms of the ‘calcium hypothesis’ of transmitter release.