bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response latency of brisk‐sustained (X) and brisk‐transient (Y) cells in the cat retina
Authors: Bolz J. , Rosner G. , Wässle H. 
Published: December 2014

1. Several methods for evaluating light‐evoked response latency and its variability in brisk‐sustained (X) and brisk‐transient (Y) retinal ganglion cells were tested. The most accurate procedure proved to be that described by Levick (1973), in which the time of the occurrence of the fourth impulse after stimulus onset is taken as an estimate of the latency.2. The shortest response latencies are obtained when the stimuli are the same size as the receptive field centre. At medium and high response amplitudes (> 150 impulses/sec) the response of brisk‐transient (Y) cells to these optimal stimuli is 10‐15 msec faster than that of adjacent brisk‐sustained (X) cells.3. The response latency of brisk‐sustained (X) cells for stimuli larger than the receptive field centre increases, whereas that of brisk‐transient (Y) cells remains constant. Brisk‐sustained (X) cells respond faster than do brisk‐transient (Y) cells to stimuli smaller than the receptive field centre.4. No systematic difference exists between brisk‐sustained (X) and brisk‐transient (Y) cells in regard to the temporal variability of the response. The standard deviation of the latency for stimuli of optimal size decreases from 2·0‐8·0 msec at medium stimulus contrast to 0·6‐2·0 msec at high stimulus contrast.5. The response of OFF‐centre cells to the disappearance of a light spot is always slower than that of an ON‐centre cell of the same class to the onset of this stimulus. However, when OFF‐centre cells are stimulated with dark spots, their response latency does not differ from that of ON‐centre cells of the same class.6. No simple relationship exists between the response latency and the response amplitude. At medium and high discharge rates, most brisk‐transient (Y) cells respond faster than an adjacent brisk‐sustained (X) cell with equal response. At the same response amplitude, the latencies become shorter as the background illumination is raised. The same discharge rate can be obtained with stimuli of sub‐optimal and supra‐optimal size, but the latency for the larger stimulus is shorter than that for the smaller one. Latency, therefore, is an additional parameter characterizing the light‐evoked response.
Voltage‐ and stage‐development uncoupling of Rohon‐Beard neurones during embryonic development of Xenopus tadpoles
Authors: Spitzer Nicholas C. 
Published: December 2014

1. Electrical coupling of Rohon‐Beard neurones in the spinal cord of Xenopus laevis has been studied from the time of closure of the neural tube (stage 20, 22h after fertilization of the egg) to the free swimming tadpole (stage 49, 12d old). Pairs of cells were examined by impaling both simultaneously with single micro‐electrodes having current‐passing and voltage‐recording capabilities.2. At the earliest time studied (stage 20), before Ca2+ action potentials are detected, cells are electrically coupled. Coupling coefficients as high as 0·6 can be recorded. Tests with small hyperpolarizing and depolarizing current pulses demonstrate that the coupling does not show rectification.3. The coupling is voltage‐dependent: depolarization or hyperpolarization of one cell with respect to another, above a threshold, causes relative uncoupling of the cells. The coupling coefficient falls to ∼10% of its initial value when the difference in potential between the two cell bodies is ∼75 mV. Cells usually become recoupled at the termination of the current pulse. Other, unidentified cells in the spinal cords of the same embryos show coupling that is not voltage‐dependent.4. Voltage‐dependent uncoupling and recoupling persist when cells are depolarized by high K+, and in the presence of 30 mM‐Co2+, suggesting that chemical synapses are not involved. They are also unaffected by addition of Rb+, Cs+ or TEA+ to the extracellular solution, elevated levels of Ca2+, or replacement of Na+ with Tris or Cl− with isethionate, suggesting that conductance changes in the surface membrane, such as anomalous rectification, are not responsible.5. Lowering the intracellular pH with CO2‐HCO3− buffered saline does not abolish electrical coupling but appears to eliminate its voltage dependence.6. Slightly later (e.g. stage 21), cells that do not yet produce Ca2+ action potentials while coupled will do so when their input resistance is increased by uncoupling them from their neighbours.7. Later still (e.g. stage 23), cells make Ca2+ action potentials while coupled, and an action potential in one cell can trigger an action potential in other cells to which it is coupled. Ca2+ action potentials that do not bring other coupled cells to threshold for impulse initiation can transiently reduce the strength of coupling. Repetitive firing of these Ca2+ action potentials at a low frequency does not cause permanent uncoupling of the cells.8. Rohon‐Beard neurones become electrically uncoupled about stage 25 (early tail‐bud, 28h old). Coupling disappears around the time of appearance of the Na+ component of the action potential, although coupling that is voltage‐dependent or independent can still be seen between other, unidentified cells. No electrical coupling of Rohon‐Beard cells was detected at later stages of development.
Redistribution by 5‐hydroxytryptamine of carotid arterial blood at the expense of arteriovenous anastomotic blood flow
Authors: Saxena Pramod R. , Verdouw Pieter D. 
Published: December 2014

1. The effects of 5‐hydroxytryptamine by intravenous (1, 5 and 10 μg kg−1 min−1 in cats) and intracarotid (0·5 and 2 μg kg−1 min−1 in pigs) routes were studied on the complete distribution of common carotid artery blood flow, measured with radioactive microspheres (15 μm). In addition, the amine was also infused (0·75‐3 μg kg−1 min−1) into the carotid artery of cats to observe its influence on the shunting of microspheres in the jugular venous blood.2. The basal total common carotid blood flow was distributed ipsilaterally mainly to extracerebral tissues and only little blood entered the brain. As shown by the presence of microspheres in the lungs after injection into the carotid artery (52% in cats; 82% in pigs), a major fraction of the carotid blood by‐passed the capillary bed through arteriovenous anastomoses in the head (non‐nutrient fraction).3. 5‐Hydroxytryptamine redistributed the blood in favour of the nutrient compartment at the expense of arteriovenous anastomotic fraction. In cats, tissue blood flow did not significantly change but, in the pig, blood flow to all tissues, particularly to skin and ears, was substantially increased despite a reduction in total carotid blood flow. This reduction was entirely due to a change in the non‐nutrient fraction.4. Intracarotid infusion of 5‐hydroxytryptamine in vagosympathectomized intact or spinal cats decreased the number of microspheres appearing in the jugular venous blood, again indicating a reduction in arteriovenous anastomotic flow due to a constriction of these non‐nutrient vessels.5. Cyproheptadine (1 mg kg−1) completely reversed the effect of 5‐hydroxytryptamine on the total carotid blood flow. However, the vasoconstriction of arteriovenous anastomoses was only partially attenuated and the vasodilatatory response was either unchanged (muscle) or even enhanced (skin, ear and bones).6. It is suggested that 5‐hydroxytryptamine causes vasoconstriction of the large arteries via D‐receptors which are only partly involved in the constriction of arteriovenous anastomoses. A part of the vasoconstriction in these non‐nutrient vessels and the vasodilatation in extracerebral tissues are mediated by atypical 5‐hydroxytryptamine receptors that are yet to be fully characterized.
Effects of calcium and manganese ions on mechanical properties of intact and skinned muscles from the guinea‐pig stomach
Authors: Itoh Takeo , Kuriyama Hirosi , Nanjo Tamaki 
Published: December 2014

1. To investigate the mechanism of generation of contractions in tissues from the guinea‐pig stomach, the effects of caffeine, procaine, acetylcholine (ACh), diltiazem or MnCl2 on the contraction evoked from small bundles of intact or skinned muscles (50 μm in width and 250‐300 μm in length) were observed.2. All these agents except for ACh blocked the spontaneously generated contraction. Diltiazem (1 × 10−4
m) had no effect and MnCl2 (3 m
m) slightly reduced and caffeine enhanced the tonic contraction evoked in Na‐free solution, whereas procaine relaxed the tissue. On the other hand, in the isotonic [K]o solution, diltiazem, MnCl2 and procaine relaxed the tissue, while caffeine enhanced the tonic contraction.3. Under pre‐treatment with Ca‐free solution (2 m
m‐EGTA‐containing solution) after depletion of the stored Ca, application of 2·5 m
m‐Ca and subsequently applied 5 m
m‐caffeine produced contractions (Ca‐ and caffeine‐induced contractions, respectively). In polarized (5·9 m
m‐Ko) and depolarized (128 m
m‐Ko) muscles, the various agents simultaneously applied with 2·5 m
m‐Ca modified the amplitude of the Ca‐induced and the resulting caffeine‐induced contractions. Thus, at least three different Ca influxes required to evoke the Ca‐ or caffeine‐induced contraction were identified; diltiazem‐sensitive Ca influx, diltiazem‐insensitive but Mn‐sensitive Ca influx and Mn‐insensitive Ca influx.4. The Ca‐ and caffeine‐induced contractions in Ca‐free and 15·5 m
m‐Na‐containing solutions were gradually reduced in amplitude, in proportion to the time of exposure. However, amplitude of the caffeine‐induced contractions was inhibited to a greater extent and the duration of the contracts was less prolonged than the case of the Ca‐induced contraction.5. In saponin‐treated skinned muscles, the minimum concentration of Ca required to produce the contraction was 1 × 10−7
m, and the maximum contraction was evoked by application of 1 × 10−5
m‐Ca. The effects of Na‐free solution on the Ca accumulation and release to and from the storage site were also observed in these skinned muscles. The removal of Na from the cell seems to accelerate the Ca leakage, and depletes the stored Ca. In addition, Na‐free solution inhibits to some extent the accumulation of Ca in the store site.6. In skinned muscles, Mn (over 2 × 10−9
m) significantly enhanced the Ca‐induced contraction and the pCa—tension relationship shifted to the left and upper directions. Mn seemed to possess the property of activating the contractile proteins, as determined from the pMn—tension relationship, and this agent may also inhibit leakage of Ca from the store sites. However, in relation to the latter two actions, the possible effects of Ca contaminations in the solution would have to be ruled out. Under physiological conditions, MnCl2 may act at the level of the myoplasmic membrane and not actually penetrate the cell in this tissue.
Quantitative differences in the currents of bursting and beating molluscan pace‐maker neurones
Authors: Gorman A. L. F. , Hermann A. 
Published: December 2014

1. The spontaneous activity and the membrane conductances to Na+, Ca2+ and K+ ions of the bursting pace‐maker neurone R‐15 and the repetitively discharging (beating) pace‐maker neurone L‐11 in the abdominal ganglion of the marine mollusc, Aplysia californica, were compared.2. The bursting pace‐maker R‐15 can be converted to a beating pace‐maker neurone by the removal of external Ca2+ or by the injection of EGTA intracellularly. Bursting pace‐maker activity is not restored by changes in the resting potential.3. Spontaneous action potentials of cell R‐15 are reduced, but not abolished, by the addition of tetrodotoxin (TTX) to block Na+ currents or by the removal of external Ca2+ to abolish Ca2+ currents, whereas the spontaneous action potentials of cell L‐11 are abolished by external TTX, but are unaffected by external Ca2+ removal.4. The membranes of both cells contain Na+ and Ca2+ inward currents. The specific Na+ conductance of both cells is of similar magnitude, whereas the specific Ca2+ conductance is about half the Na+ conductance in R‐15 cells and an order of magnitude smaller in L‐11 cells.5. The delayed K+ conductance of cell L‐11 is about 1·2 times greater than this conductance in cell R‐15. The transient K+ currents of the two cells are about the same magnitude.6. The Ca2+‐activated K+ conductance of cell R‐15 and cell L‐11 was estimated using two methods. The Ca2+‐activated K+ conductance of cell R‐15 estimated from the difference in the total outward current in normal external solution and the delayed K+ current in Ca2+‐free solution (to preclude Ca2+ influx) or after internal EGTA injection (to prevent Ca2+ accumulation) is about 23 times greater than this conductance in cell L‐11. The Ca2+‐activated K+ conductance of cell R‐15, estimated from local internal Ca2+ injections in Ca2+‐free solution, is about 3 times greater than this conductance in cell L‐11.7. The leakage conductance of cell L‐11 is about 1.3 times greater than this conductance in cell R‐15. This conductance increases by a factor of about 2 in both cells in Ca2+‐free external solutions containing 1 mM‐EGTA, but is unchanged or is decreased slightly by injection of EGTA internally.8. It is concluded that the Ca2+ conductance and the Ca2+‐activated K+ conductance are appreciably greater in the bursting pace‐maker neurone R‐15 than in the beating pace‐maker neurone L‐11, whereas other voltage‐dependent conductances to Na+ and K+ ions as well as the leakage conductance are quite similar. These quantitative differences provide a basis for understanding the different spontaneous activities of the two cells.
Trophism between C‐type axon terminals and thoracic motoneurones in the cat
Authors: Pullen A. H. , Sears T. A. 
Published: December 2014

1. Quantitative ultrastructural examinations of axon terminals synapsing with normal α‐motoneurones in segment T9 of cat spinal cord provided estimates of their numbers, sizes and synaptic structure. One synapse, the C type, derived from short‐axon propriospinal segmental interneurones, was studied in detail.2. The numbers, sizes and post‐synaptic structure of normal C‐type synapses at T9 were compared with similar estimates from material provided by cats subjected to partial central deafferentation by double spinal hemisection at T5 and T10 between 7 days and 2 years previously.3. The proportion of C‐type synapses present progessively increased from 1% in normal cats to 8·8% 200 days following hemisection, and had still attained a level of 3·1% by 2 years; these increases imply that the absolute number of C‐type synapses underwent increase.4. Mean sizes of C‐type synapses increased from 4·0 μm (normal) to 5·8 μm (200 days) and retained their enlarged sizes up to 2 years (5·9 μm). Furthermore, while 84% of C‐type synapses were under 6 μm in length in normal motoneurones, 48% were over 6 μm long 200 days post‐operatively.5. The unique post‐synaptic structure of C‐type synapses also proliferated following partial central deafferentation of the motoneurones. The elongated cistern, increased numbers and individual lengths of lamellae of the associated underlying rough endoplasmic reticulum indicated a trophic interaction between the presynaptic C terminal and its post‐synaptic motoneurone.6. Counts of ribosomes ‘bound’ to lamellae of the subsynaptic rough endoplasmic reticulum, and of the lamellae‐associated polyribosomes interposed between individual lamellae for normal and 200 day post‐operative C‐type synapses indicated an over‐all post‐operative increase in capacity for local subsynaptic protein synthesis topographically directed towards this type of axon terminal.7. The observed greater increase in frequency of ribosomes ‘bound’ to the rough endoplasmic reticulum, together with an over‐all proliferation of this structure, specificially indicated an increased capacity for synthesis of protein for utilization in sites remote from those of synthesis (e.g. a trans‐synaptic passage of protein).8. A hypothesis is advanced on the basis of the above results relating both pre‐ and post‐synaptic changes in structure to an increased functional activation of the segmental short‐axon propriospinal interneurones forming the C‐type synapses, as a compensatory response to partial central deafferentation of spinal motoneurones.
Axonal morphological changes following impulse activity in mouse peripheral nerve in vivo: the return pathway for sodium ions
Authors: Trigo Diogo , Smith Kenneth J. 
Published: December 2014

Key points
Conduction in myelinated axons involves substantial ion movements that must be reversed to restore homeostasis.
The pathway taken by sodium ions returning to their original location and the potential osmotic consequences are currently unknown.
We report striking morphological changes in axons following sustained impulse conduction that appear to result from osmosis and to indicate accumulation of ions in the periaxonal space followed by their release at the paranode.
We conclude that the morphological changes illustrate a hitherto unrecognized part of normal axonal physiology that may also indicate the return pathway for the sodium ions involved in impulse formation.
AbstractMyelinated axons can conduct sustained trains of impulses at high frequency, but this involves substantial ion movements that must be reversed to restore homeostasis. Little attention has been paid to the potential osmotic consequences of the ion movements or to the pathway taken by sodium ions returning to their original endoneurial location, given that the axolemmal Na+–K+‐ATPase extrudes these ions into the periaxonal space beneath the myelin rather than into the endoneurium. Serial confocal imaging of fluorescent axons conducting at sustained physiological frequencies in vivo has revealed surprising morphological changes that may illuminate these problems. Saphenous nerves and spinal roots of anaesthetized transgenic mice expressing axoplasmic yellow fluorescent protein were stimulated electrically or pharmacologically (veratridine). Within 2 h, the axon herniated on one or both sides of the nodal membrane, displacing the paranodal myelin and widening the nodal gap. The herniated axoplasm became directed back towards the internode, forming a ‘cap’ up to 30 μm long. Concurrently, the fluid in the expanded periaxonal space accumulated into droplets that appeared to travel to the paranode, where they escaped. No such alterations occurred in axons treated with sodium channel or Na+–K+‐ATPase inhibitors. Remarkably, impulse conduction continued throughout, and all these changes reversed spontaneously over hours or days. The morphological changes were verified ultrastructurally, and occurred in virtually all myelinated axons. The findings appear to reveal an overlooked part of the physiological repertoire of nerve fibres, and here they are interpreted in terms of osmotic changes that may illuminate the pathway by which sodium ions return to the endoneurial space after they have entered the axon during impulse conduction.
Modeling, Validation, and Vibration Reduction in an Electronic Stethoscope
Authors: Nelson Garrett , Rajamani Rajesh , Erdman Arthur 
Published: December 2014

This paper focuses on the influence of noise and vibration on auscultation with a digital stethoscope. Two types of vibrations, namely inputs through the patient chest and disturbances from the physician, influence the auscultation signal. The goal of this work is to reduce the influence of disturbances from the physician on the stethoscope’s digital signal without effectively reducing the coupling between the transducer and the patient’s chest.
A multi-DOF rigid body vibration model consisting of discrete connected components is developed for a digital stethoscope. The model is experimentally validated and its parameters identified by using a thorax simulator and vibration shaker. The introduction of vibration isolation so as to reduce the influence of physician noise on the transducer is then pursued. It is shown that directly introducing soft foam vibration isolation between the transducer and the rest of the stethoscope structure leads to a reduction in coupling with the patient’s chest. On the other hand, if the vibration isolation is introduced between the heavy transducer housing above the transducer and the rest of the stethoscope, then vibration isolation from the physician is achieved with a much less reduction in patient coupling. Experimental results are presented to study the influence of the proposed design changes.
Comparison of Three — Easy to Apply and Innovative — Signal-Based Approaches for Diagnosis of a Technical System With Wear
Authors: Söffker D. , Rothe S. 
Published: December 2014

Ensuring the reliability and availability of complex systems such as safe mechatronic systems or cost-sensitive machine components is of increasing importance. Besides the availability of problem-specific sensors and filtering techniques three major issues are of interest:
i) Preparation of the measured data (filtering),
ii) Interpretation of the data with respect to the machines state as well as to the machines’ remaining lifetime or guaranteed functionality, and
iii) establishing the required knowledge behind from available measurements and data.
Core of this contribution is the development and application of easy to apply and easy to interpret algorithms to be used directly with industrial data or measurements from technical systems in operation.
The three approaches applied are
AI: Acoustic Emission (AE) characterized by measurements in combination using a suitable filter to be designed,
AII: data analysis using operating system data feature capturing technique, and
AIII: Adaptive fuzzy-based filtering [1] with training and classification modules.
The approaches are developed in detail due to former research work [2], here they are applied and compared using the same experiment, the shown results are based on experiments. The three approaches use different algorithms but partially different signal sources (from the same experiment). Each of the approaches allows a different and distinguished problem-oriented insight to the complex wear process of the considered system, typical for mechanical engineering-related machines. The comparison between three different approaches for wear diagnosis can be considered as the main idea of this paper which allows insights into the advantages and disadvantages of each of these approaches.
Parental Influences on Preschoolers’ TV Viewing Time: Mediation Analyses on Australian and Belgian Data
Authors: De Decker Ellen , Hesketh Kylie , De Craemer Marieke , Hinkley Trina , De Bourdeaudhuij Ilse , Salmon Jo , Cardon Greet 
Published: December 2014

Background:Television viewing is highly prevalent in preschoolers (3–5 years). Because of the adverse health outcomes related to this behavior, it is important to investigate associations and mediators of young children’s television viewing time. This study investigated whether parental rules regarding television viewing time and parental concerns about screen viewing activities mediated the association between parents’ and preschoolers’ television viewing time.Methods:Mediation analyses were performed with the product-of-coefficient test on data derived from the Australian HAPPY study (n = 947) and the Belgian sample of the ToyBox-study (n = 1527). Parents reported their own and their child’s television viewing time, their rules regarding television viewing and concerns about their child’s screen viewing activities.Results:Parents’ television viewing time was directly associated with preschoolers’ television viewing time and parental rule for television viewing time mediated this association in both samples (14.4% and 8.1% in the Australian and Belgian samples, respectively).Conclusions:This study is unique in examining the mediating pathway of parental television viewing and a rule limiting TV viewing time and whether this is consistent in different samples. Due to the consistent importance, both parents’ television viewing time and rules should be targeted in interventions to decrease preschoolers’ television viewing time.