bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cholinergic and catecholaminergic receptors in the Xenopus oocyte membrane
Authors: Kusano K. , Miledi R. , Stinnakre J. 
Published: December 2014

1. Neurotransmitter‐receptors in the membrane of Xenopus oocytes have been studied using electrophysiological techniques. Neurotransmitters and related agents were applied while recording either membrane potential or membrane current. The majority of ovarian oocytes used were at stages IV and V.2. Three types of oocytes were examined: inner ovarian epithelium covered (e.c.) oocytes; epithelium manually removed (e.r.) oocytes; and collagenase treated (c.t.) ooctyes.3. Ovarian oocytes are sensitive to some cholinergic and catecholaminergic agents. Responses to serotonin were seldom observed and when present were much weaker than responses to other agents. No responses were observed to the amino acids: aspartate, glutamate, γ‐aminobutyric acid, and glycine; or to octopamine and histamine.4. Acetylcholine (ACh) usually depolarized the membrane, in a dose‐dependent manner, with threshold concentrations as low as 10−9
m. The ACh‐potential was due to an increase in Cl permeability and had a reversal potential around — 19 mV. The intracellular Cl ion activity, measured with a Cl‐ion sensitive micro‐electrode, was about 65 m
m and the estimated Cl‐ion equilibrium potential, ECl, agreed with the reversal potential of the ACh‐potential.5. Curare (10−4
m), tetrodotoxin (10−6
m), or α‐bungarotoxin (10−6 g/ml.) did not block the response to 10−6
m‐ACh; whereas atropine (10−7
m) blocked it. No response to nicotinic agents (e.g. nicotine, 1,1‐dimethyl‐4‐phenylpiperazinium) was observed. These results suggest that the ACh receptors in the oocyte membrane are muscarinic in nature.6. The apparent latency of the ACh potential, examined by ionophoretic application of ACh to e.r. oocytes and c.t. oocytes, ranged from 0·5 sec to over 20 sec. Intracellular injection of ACh was without effect.7. Responses to catecholamines were observed mostly in e.c. oocytes; while in e.r. and c.t. oocytes they were rare and of very small amplitudes.8. The usual response to both dopamine and (—)‐epinephrine was a transient hyperpolarization manifested by an initial increase in K‐permeability followed by a decrease. The latency of these responses ranged from 10 sec to over 30 sec and their reversal potential was nearly — 100 mV, which coincided with EK.9. Oocytes responded to the β‐adrenergic receptor agonist, isoproterenol, as well as (—)‐epinephrine. Pre‐treatment with the β‐adrenergic receptor blocker, propranolol, abolished the response to both (—)‐epinephrine and (—)‐isoproterenol. The dopamine potential was also reduced considerably. Both the α‐adrenergic receptor agonist, phenylephrine, and the α‐adrenergic receptor blocker, phentolamine, were without effect.10. Maturation of the oocytes, induced in vivo by gonadotropin or in vitro by progesterone, led to loss of responsiveness to both cholinergic and catecholaminergic agents.
An electrophysiological study of somatic and visceral convergence in the reflex control of the external sphincters
Authors: McMahon S. B. , Morrison J. F. B. , Spillane Kathy 
Published: December 2014

1. Mass wave and single unit discharges have been recorded from pudendal efferents innervating the external anal and urethral sphincters in chloralose anaesthetized or decerebrate cats.2. Reflex discharges in these neurones were elicited by electrical stimulation of the contralateral pudendal nerve, the posterior cutaneous nerve of thigh, or the vesical or colonic branches of the pelvic nerve. The latencies of the evoked responses were 5·5‐20 msec. The vesical branches of the pelvic nerve produced discharges less consistently than the other nerves.3. Irrespective of whether afferent stimulation produced an early evoked response there was always a prolonged period of depression of pudendal nerve excitability following the stimulus. Condition—test interactions showed that this depression began within 50 msec of the stimulus and that its duration varied between 150 and 2500 msec in single units, with a modal value of 500 msec.4. No evoked response or depression of excitability was seen when afferents in the hypogastric or lumbar colonic nerves were stimulated.5. Increasing intravesical or intracolonic pressure, within physiological limits, produced a graded reduction in the size of evoked discharges.6. Short trains of stimuli (four shocks in 20 msec) applied to the raphé nucleus, were capable of inhibiting test responses in pudendal efferents for periods of up to 800 msec.7. The possible functional roles of two groups of sphincteric reflex interneurones, with either excitatory or inhibitory receptive fields, are discussed.
The effect of horizontal‐plane environment on the development of binocular receptive fields of cells in cat visual cortex
Authors: Hänny P. , von der Heydt R. 
Published: December 2014

1. The different perception of vertical in the two eyes (Helmholtz, 1864) was interpreted as an adaptation of cortical binocular receptive fields to the bias distribution of orientation disparity in the visual environment resulting from the relative frequency of contours in horizontal planes below eye level (ground, table) compared to other orientations in space.2. Kittens were reared in environments where visible contours were confined to a horizontal plane which was the floor for two kittens and the ceiling for two other kittens. The floor tended to produce negative, the ceiling positive, orientation disparities. In either case, the disparities were maximal about the vertical retinal meridians and zero at the horizontal meridian. The preferred stimulus orientations of binocular neurones in area 17 of the visual cortex were determined at 3‐4 months age in these four kittens and in seven normal cats for control. Automatic stimulus variation, quantitative analysis, and eye drift correction were used.3. In the ‘floor cats’ neurones with near‐vertical orientations showed a mean interocular angle between the preferred orientations of ‐8.7° relative to neurones with near‐horizontal orientations; in the ‘ceiling cats’, the angle was +2.8°; in the normal cats it was ‐0.4°.4. Since these angles are independent of the alignment of the eyes, the difference between floor cats and ceiling cats reflects different functional connexions at cortical level. This indicates that the orientations of the developing receptive fields can be modified by visual experience.5. These observations in kittens suggest that the perceptual difference between the eyes in man is also caused by early visual experience.
Behaviour of human motor units in different muscles during linearly varying contractions
Authors: de Luca C. J. , LeFever R. S. , McCue M. P. , Xenakis A. P. 
Published: December 2014

1. The electrical activity of up to eight concurrently active motor units has been recorded from the human deltoid and first dorsal interosseous (f.d.i.) muscles. The detected myoelectric signals have been decomposed into their constituent motor‐unit action potential trains using a recently developed technique.2. Concurrently active motor unit behaviour has been examined during triangular force‐varying isometric contractions reaching 40 and 80% of maximal voluntary contraction (m.v.c.). Experiments were performed on four normal subjects and three groups of highly trained performers (long‐distance swimmers, powerlifters and pianists).3. Results revealed a highly ordered recruitment and decruitment scheme, based on motoneurone excitability, in both muscles and in all subject groups.4. Differences were observed between the initial (recruitment) and final (decruitment) firing rates in each muscle. These parameters were invariant with respect to the force rates studied, although some differences were observed among subject groups.5. In general, firing rates of f.d.i. motor units increased steadily with increasing force (up to 80% m.v.c.). The firing rates of deltoid motor units rose sharply just after recruitment and then increased only slightly thereafter.6. Recruitment was found to be the major mechanism for generating extra force between 40 and 80% m.v.c. in the deltoid, while rate coding played the major role in the f.d.i.7. The potential of rate coding for increasing force levels up to m.v.c. is discussed.
Stimulation of calcium‐dependent release of labelled protein from pulse‐labelled mouse pituitary intermediate lobe tissue
Authors: Thornton V. F. 
Published: December 2014

1. The effect of K depolarization on the release of labelled protein from pulse‐labelled intermediate lobe tissue of mouse pituitaries has been studied.2. Depolarization briefly stimulated Ca‐dependent release of labelled protein. Co (2·5 mM) and verapamil (0·08 mM) reversibly blocked stimulation. Efflux of 45Ca was also briefly stimulated by depolarization, but not in the presence of Co or verapamil, nor in the absence of Ca.3. The response to maintained depolarization quickly inactivated. Inactivation probably resulted from Ca‐channel inactivation rather than exhaustion of available labelled protein, since responses different in magnitude but of constant time course could be obtained by depolarization in different concentrations of Ca. In addition, much more labelled protein could be released by exposure to Ba.4. Depolarization did not cause a response if the Ca concentration was 0·4 mM or less; neither did inactivation occur in these conditions, and a response occurred as soon as the Ca concentration was raised. Two separate responses could be generated by a stepwise increase in the Ca concentration during maintained depolarization. The magnitude of the two responses together was similar to the magnitude of one response at the higher Ca concentration.5. Recovery from inactivation was complete after about 20 min in normal K. However, recovery also occurred during maintained depolarization provided the Ca concentration was reduced sufficiently. Recovery was complete at 0·4 mM‐Ca or less, and at higher concentrations the extent of recovery depended on the Ca concentration selected.6. It is concluded that depolarization opened potential‐dependent Ca channels permitting Ca entry and causing the release of labelled products. The response was brief probably because the Ca channels were inactivated. Since the channels were not inactivated by depolarization in low Ca, inactivation may result from Ca entry.
Short‐ and long‐term effects of paralysis on the motor innervation of two different neonatal mouse muscles
Authors: Brown M. C. , Hopkins W. G. , Keynes R. J. 
Published: December 2014

1. A study was made of short‐ and long‐term effects of paralysis induced by type A botulinum toxin on the development of innervation of mouse muscles. The toxin was injected locally over the tensor fasciae latae (t.f.l.) and gluteus muscles at various times after birth, and the innervation was later examined by intracellular recording and by a histological technique using a reduced silver stain for axons.2. Paralysis induced at 0‐4 days of age delayed but did not prevent the eventual elimination of nearly all focal multiple innervation in gluteus muscle fibres, whereas in t.f.l. up to 50% of the fibres remained focally innervated by more than one axon for at least 120 days. There was an associated reduction in the number of muscle fibres in t.f.l. of between 50 and 70%. The biggest reduction in the number of gluteus fibres was under 40%.3. In the t.f.l., paralysis begun at 6‐9 days caused the extent of single‐site polyneuronal innervation to increase above the level existing at the time of paralysis. Histologically this increase was seen to be due at least in part to the stimulation of nodal sprout growth from a limited number of nodes.4. Motor nerve terminal sprouts were evoked by paralysis at all ages. In mice injected before 4 days of age recovery from the toxin occurred rapidly and without the formation of ectopic synapses by sprouted motor terminals; however, intrafusal motor nerves also sprouted and established a permanent ectopic innervation on surrounding extrafusal muscle fibres.5. The following conclusions are drawn. (a) In some but not all muscles, neonatally induced paralysis can not only temporarily halt elimination of polyneuronal innervation but actually lead to an increase; it is suggested tentatively that this occurs only during the neonatal period because of the availability at that time of endoneurial pathways associated with normal polyneuronal innervation, rather than because of any special neuronal growth potential then. (b) Permanent establishment of focal polyneuronal innervation is due not to stability of presynaptic elements maintained past a critical developmental stage but is associated with substantial losses of muscle fibres, leading to a high ratio of nerve fibres to muscle fibres.
Fibre types in chicken skeletal muscles and their changes in muscular dystrophy
Authors: Barnard E. A. , Lyles Joan M. , Pizzey J. A. 
Published: December 2014

1. Five major fibre types in chicken skeletal muscles are recognized, based upon their histochemical and morphological characteristics. A classification of these which is readily related to a commonly used classification of mammalian muscle fibre types is given.2. Seven muscles of the chicken were analysed in recognizing this range of fibre types. The proportions of the different types in each of these were determined. In some cases a gradient of fibre type composition exists across a single muscle.3. Measurements of muscle contraction were used in defining tonic muscles, which contain two fibre types. It was shown that in addition to the anterior latissimus dorsi (a.l.d.), previously well known to be a tonic muscle, two other muscles, the plantaris and the adductor profundus, are of the same class, but differ subtly from the a.l.d. in certain features. Gross red colouration is not a useful diagnostic feature of slow muscles, since the tonic adductor profundus, for example, is white.4. Fibres similar histochemically to mammalian type I (slow‐twitch) occur in some of the avian twitch muscles investigated. These are oxidative in character, and despite the fact that they are multiply innervated we suggest that these are avian slow‐twitch fibres.5. The patterns of cholinesterases found in a skeletal muscle correspond to its fibre type composition, with regard to both the concentrations and the proportions of the multiple forms of enzyme present. The distinctive patterns of those forms of acetylcholinesterase in the different fibre types are described.6. The fibre type composition is changed by inherited muscular dystrophy in a characteristic manner. This change has so far been found (at the earlier stages of the disease) only in the muscles with a predominance of type II B fibres in the normal chicken. Pathological changes within the fibres occur selectively in the type II B fibres, but there are exceptions to this and the effect can be greatly modified by the type of neighbouring fibres.
Origin of the light peak: in vitro study of Gekko gekko
Authors: Griff Edwin R. , Steinberg Roy H. 
Published: December 2014

1. The light peak is a large, light‐evoked increase in standing potential recorded in mammals, birds and reptiles. We have studied the cellular origin of the light peak in an in vitro preparation of neural retina‐pigment epithelium (r.p.e)—choroid from the lizard, Gekko gekko. The tissue was mounted between two separate bathing solutions; the trans‐tissue potential was recorded retinal‐side positive; micro‐electrodes were introduced to measure the trans‐epithelial potential (t.e.p.) and to record intracellularly from the r.p.e.2. A 10 min stimulus of diffuse white light evoked an increase in trans‐tissue potential that reached maximum amplitude, the light peak, about 15 min after stimulus onset. Since the light peak is present in vitro, it must originate in either the neural retina or the r.p.e.3. A micro‐electrode was positioned in the subretinal space and the trans‐retinal potential and t.e.p. were measured simultaneously. A 10 min stimulus produced an increase in t.e.p. equal in magnitude and time course to the trans‐tissue light peak; no potential was present across the retina. The light peak is therefore generated solely across the r.p.e.4. Intracellular r.p.e. recordings were made to determine whether the light peak was generated at the apical or basal membrane or across the paracellular shunt. A 10 min stimulus first caused a hyperpolarization of both membranes with a time course similar to the r.p.e. c‐wave followed by a depolarization of both membranes with the time course of the light peak. We conclude that whereas the r.p.e. c‐wave results from a hyperpolarization of the apical membrane, the light peak is generated by a depolarization of the basal membrane of the r.p.e.5. Changes in tissue resistance, Rt, and the ratio of apical to basal membrane resistances, a, were monitored during the light peak by passing current across the tissue and measuring the appropriate current‐induced voltages. Rt decreased and a increased with the time course of the light peak. Assuming that the paracellular shunt resistance is constant, we conclude that the light peak is accompanied by an increase in basal membrane conductance.6. This and the following paper present the first direct demonstration of an interaction between the neural retina and the basal membrane of the r.p.e. The light peak, initiated by absorption of light by photoreceptors, results in a depolarization and conductance increase of the basal membrane.
Renin‐induced sodium appetite: effects on sodium balance and mediation by angiotensin
Authors: Avrith D. B. , Fitzsimons J. T. 
Published: December 2014

1. Injection of pig renin or purified renin from the mouse submaxillary gland into the preoptic region or third ventricle of the rat caused thirst within a minute or so of injection followed shortly afterwards by increased sodium appetite. Renin from two widely different sources produced identical responses.2. The stimulating effect of renin on intake of water and hypertonic (2·7%) NaCl was continuous and persisted for at least a week after the largest (265 ng) dose of purified renin.3. The stimulating effect was also very large. A single preoptic injection of less than 0·75 pmol (26·5 ng) purified mouse renin caused mean intakes of 250·4 ± 26·2 ml water and 44·8 ± 12·5 ml 2·7% NaCl by five naive rats in 24 h. After the largest dose (265 ng) intakes of water and 2·7% NaCl reached about 80% and 20% body weight respectively.4. Weekly injections of renin resulted in progressively larger intakes of NaCl and water in response to the injections.5. Even after repeated injections, carbachol did not stimulate sodium appetite. The stimulating effect on water intake was quickly over and showed no progressive increase with repeated injections. Overnight intake of water was generally depressed after carbachol.6. Preoptic injection of renin caused some increase in sodium excretion but this was small compared with the stimulating effect on sodium appetite.7. Detailed temporal analysis of fluid and sodium balance shows that the increased intakes of water and 2·7% NaCl were not secondary to renin‐induced urinary losses. Increased intakes of water and 2·7% NaCl caused by renin resulted in the rats going into and remaining in positive fluid and sodium balance throughout the 24 h experiment.8. Renin‐induced sodium appetite and thirst were inhibited by the converting enzyme inhibitors teprotide or captopril, or by the angiotensin antagonist saralasin. Inhibition was longer lasting after captopril. Carbachol‐induced thirst was unaffected.9. In conclusion, renin injected into the preoptic region or third ventricle is a potent stimulus to sodium appetite as well as thirst. The effect is mediated by local generation of angiotensin II and it is not secondary to increased urinary loss.
An Ultrasonic Approach for Sensing and Imaging Shielding Containers of Nuclear Threats
Authors: Martínez Lorenzo José Á. , Álvarez López Yuri 
Published: December 2014

A new guided wave imaging application for fast, low-cost ultrasound-based cargo scanning system is presented. The goal is the detection of high-atomic-number, shielding containers used to diminish the radiological signature of nuclear threats. This ultrasonic technology complements currently deployed X-ray-based radiographic systems, thus enhancing the probability of detecting nuclear threats.
An array of acoustic transceivers can be attached to the metallic structure of the truck to create a guided acoustic wave. Guided medium thickness and composition variation creates reflections whose placement can be revealed by means of an imaging algorithm. The knowledge of the reflection position provides information about the shielding container location inside the truck.
Reflected waves in the guided domain bounds may limit the performance of imaging methods for guided media. This contribution proposes a solution based on Fourier domain analysis, where plane wave components can be filtered out, thus removing non-desired contributions from bounds. Apart from this, the imaging algorithm can be used to recover information about material composition. Simulation-based examples are used for algorithm validation.
Paternal Lifestyle-Related Parenting Practices Mediate Changes in Children’s Dietary and Physical Activity Behaviors: Findings From the Healthy Dads, Healthy Kids Community Randomized Controlled Trial
Authors: Lloyd Adam B. , Lubans David R. , Plotnikoff Ronald C. , Morgan Philip J. 
Published: December 2014

Background:This study examined potential parenting-related mediators of children’s physical activity and dietary behavior change in the Healthy Dads, Healthy Kids (HDHK) community program.Methods:A randomized controlled trial was conducted with 45 overweight/obese (mean [SD] age = 39.8 [5.4] years; BMI = 32.4 [3.8]) fathers and their children (n = 77; 58% boys; mean [SD] age = 7.7 [2.5] years). Families were randomized to either the HDHK program or wait-list control group. The program involved 7 sessions. Fathers and their children were assessed at baseline and at 14 weeks for physical activity (pedometery) and core food intake (Questionnaire). Fathers’ lifestyle-related parenting practices included; self-efficacy, beliefs, modeling, logistic support, rules, cophysical activity, shared mealtime frequency and intentions.Results:Significant intervention effects were found for cophysical activity and modeling physical activity. Cophysical activity mediated children’s physical activity in the intervention (‘mediated effect,’ AB = 653, 95% CI = 4–2050) and was responsible for 59.5% of the intervention effect. Fathers’ beliefs mediated children’s percent energy from core foods (AB = 1.51, 95% CI = 0.05–5.55) and accounted for 72.9% of the intervention effect.Conclusions:Participation in the HDHK program positively impacted on fathers’ cophysical activity with their child and beliefs about healthy eating which mediated changes in children’s diet and physical activity behaviors.
Comparative Genome Analysis of Two Isolates of the Fish Pathogen Piscirickettsia salmonis from Different Hosts Reveals Major Differences in Virulence-Associated Secretion Systems
Authors: Bohle Harry , Henríquez Patricio , Grothusen Horst , Navas Esteban , Sandoval Alvaro , Bustamante Fernando , Bustos Patricio , Mancilla Marcos 
Published: December 2014

ABSTRACT

Outbreaks caused by
Piscirickettsia salmonis
are one of the major threats to the sustainability of the Chilean salmon industry. We report here the annotated draft genomes of two
P. salmonis
isolates recovered from different salmonid species. A comparative analysis showed that the number of virulence-associated secretion systems constitutes a main genomic difference.