bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinal dysplasia inAmerican pit bull terriers – phenotypic characterization and breeding study
Authors: Rodarte‐Almeida Ana Carolina Veiga , Petersen‐Jones Simon , Langohr Ingeborg M. , Occelli Laurence , Dornbusch Peterson T. , Shiokawa Naoye , Montiani‐Ferreira Fabiano 
Published: December 2014

AbstractObjectiveThe purpose of this study was to investigate the inheritance and phenotype of retinal dysplasia (RD) in the American pit bull terrier.Animals StudiedA breeding colony established from a single female pure‐bred American pit bull terrier dog withRD.ProceduresA female pure‐bred American pit bull terrier withRDwas donated to the Veterinary Hospital of Federal University of Paraná, Curitiba, Brazil. A breeding colony was established and the phenotype and inheritance of the condition investigated. Regular ophthalmic examinations and fundus photography were performed on three generations of offspring from the founder animal. Some animals were additionally studied by optical coherence tomography. Ocular histopathology was performed on some animals from the colony.ResultsFifty‐seven offspring were produced in two generations from the affected founder female. Thirty‐two were diagnosed withRDand showed a spectrum of severity of lesions including multifocal, and or geographic lesions and some developed retinal detachment. Histologic examination demonstrated retinal folds, rosettes, and areas of retinal detachment. The affected dogs were shorter in stature than the unaffected littermates. Breeding studies suggested the trait has an autosomal dominant mode of inheritance.DNAtesting showed that the affected dogs were negative for the known gene mutations for canine dwarfism with RD.ConclusionThis is a report of a novel inherited form of RD that affects American pit bull terriers.
The influence of conjugation of cholic acid on its uptake and secretion: hepatic extraction of taurocholate and cholate in the dog
Authors: O'Máille E. R. L. , Richards T. G. , Short A. H. 
Published: December 2014

1. Sodium taurocholate or cholate was administered systemically at a constant rate of about 2·9 μmole/min.kg body wt. to anaesthetized dogs in which the common bile duct had been cannulated. In steady‐state conditions blood was sampled from systemic and hepatic veins and the fraction of bile salt removed in a single passage through the liver was determined. Total hepatic blood flow was estimated by application of the Fick principle.2. The hepatic extraction fraction for synthetic taurocholate in ten experiments was 92%±5% (
S.D.) over the blood flow range encountered (1·1‐2·8 ml./min.g liver). The extraction of cholate extensively conjugated in the liver before excretion into bile was 79%±8% (
S.D.) (twenty‐one observations, thirteen experiments). In circumstances of similar hepatic blood flow the extraction of cholate transferred to bile in the free form (after acute taurine depletion) was significantly less than that of either synthetic taurocholate or cholate which could be actively conjugated before excretion. These results, which are discussed and criticized, support previous work on the advantage of conjugation in the transfer of cholic acid from blood to bile.3. The hepatic clearance of bile salt decreases with increasing administration rate, but the values obtained may be influenced by changes in hepatic blood flow. With regard to taurocholate an increase in total hepatic flow was observed when its administration rate exceeded about 5 μmole/min.kg body wt.4. The secretory maximum for glycocholate, a bile salt not normally found in dog bile, was of the same order as that for taurocholate.
The pH sensitivity of the chloride conductance of frog skeletal muscle
Authors: Hutter O. F. , Warner Anne E. 
Published: December 2014

1. The effect of changes in the pH of the extracellular solution on the membrane conductance of frog sartorius and toe muscle fibres was measured with intracellular micro‐electrodes.2. In Ringer solution the membrane conductance was found to be highly sensitive to changes in pH between 5·0 and 9·8. In alkaline solution the conductance rose; in acid solution it fell.3. After replacement of chloride by the relatively impermeant methylsulphate ion the membrane conductance showed little change when pH was altered. It is concluded that chloride is the ion species principally concerned in the pH sensitivity of the resting membrane conductance.4. The relation between pH and the chloride conductance was sigmoid, with the steepest part of the curve lying in the region of neutrality.5. The membrane conductance of muscles equilibrated in a 100 m
M‐K 216 m
M‐Cl solution was also sensitive to changes of extracellular pH. As in Ringer solution, the membrane conductance rose in alkaline and fell in acid solutions in a sigmoid fashion.6. Sartorius muscles in isotonic potassium methylsulphate solution showed no change in membrane conductance at different pH values.7. In chloride‐free solution a fall in pH tended to cause depolarization; a rise in pH had the opposite effect.8. In Ringer solution the initial effect of a rise in pH was usually a transient depolarization. The indication is that the intracellular concentration of chloride ions may be slightly in excess of that which corresponds to the resting potential. The long‐term effects of changes in pH on the membrane potential in Ringer solution were in the same direction as in the absence of chloride.9. The transient potential changes produced on addition and withdrawal of chloride ions were found to be larger in alkaline solutions than in acid solutions. This is further evidence for a higher chloride permeability in alkaline solutions.
Responses of the pyramidal tract to stimulation of the baboon's motor cortex
Authors: Kernell D. , Chien-Ping Wu 
Published: December 2014

1. The arm area of the baboon's precentral motor cortex was stimulated by brief surface‐anodal pulses, and the discharge of the corticospinal tract (the ‘pyramidal tract waves’) was recorded by an electrode resting on the dorsolateral surface of the cervical spinal cord.2. Some properties of the pyramidal tract waves were described, and they were also studied in relation to the firing of single cortico spinal fibres.3. The results led to the conclusion that the later pyramidal tract waves (the ‘I waves’) were almost exclusively due to a semi‐synchronous repetitive discharge of the same fast cortico spinal fibres as those responsible for the initial wave (the ‘D wave’).4. Some problems concerning the origin and significance of the I waves were discussed.
The variation of hand tremor with force in healthy subjects
Authors: Sutton G. G. , Sykes K. 
Published: December 2014

1. Total root‐mean‐square (r.m.s.) error over an effectively unrestricted band, and error power spectra from 0·256 to 12·5 c/s were measured for four subjects attempting to maintain fixed forces of 1‐6 Lb. (0·45‐2·72 kg) on a pressure joystick. The subject could see his errors as the deflexion of a cathode ray tube spot.2. The total r.m.s. error increases linearly with force with a considerable (positive) intercept when the line is extrapolated to zero force. Hence accuracy in the sense (r.m.s. error)/(force) increases with force for this type of control.3. The rate of increase of total r.m.s. error with force is greater in subjects with prominent tremor peaks in their power spectra at 8‐10 c/s.4. At each frequency the r.m.s. error per unit bandwidth also increases linearly with force. Except at the very lowest frequencies the rate of increase is greater in subjects with prominent tremor peaks at 8‐10 c/s. This is thought to account for the observation described in paragraph 3.5. The frequency of the tremor peak near 8‐10 c/s is almost independent of the force exerted.
Transport of caesium in frog muscle
Authors: Beaugé L. A. , Sjodin R. A. 
Published: December 2014

1. The entry of caesium into sartorius muscle cells is strongly suppressed by the presence of 10−5
M strophanthidin in Ringer solution.2. The amount by which caesium entry is reduced in the presence of strophanthidin is dependent on the intracellular sodium concentration and is greater the higher the intracellular sodium concentration.3. The magnitude of caesium influx in the absence of strophanthidin is highly dependent on the intracellular sodium concentration.4. Caesium uptake by muscles in which sodium has been largely replaced by lithium is reduced to very low values.5. Caesium can promote the extrusion of sodium from muscles with high intracellular sodium concentrations. The effects of 25 m
M caesium and 5 m
M potassium on sodium extrusion are roughly the same.6. External potassium inhibits the entry of caesium ions into muscle cells presumably by competing for transport sites.7. The drug strophanthidin has no effect on 134Cs efflux provided that muscles have been loaded with tracer ions for a long period of time. Caesium efflux from the intracellular compartment appears to occur by a process not mediated by metabolism.8. The action of strophanthidin on 134Cs efflux from muscles exposed to tracer for short times suggests that caesium ions are transported inwardly by an active process after first accumulating in a superficial reservoir.
Receptive fields and functional architecture of monkey striate cortex
Authors: Hubel D. H. , Wiesel T. N. 
Published: December 2014

1. The striate cortex was studied in lightly anaesthetized macaque and spider monkeys by recording extracellularly from single units and stimulating the retinas with spots or patterns of light. Most cells can be categorized as simple, complex, or hypercomplex, with response properties very similar to those previously described in the cat. On the average, however, receptive fields are smaller, and there is a greater sensitivity to changes in stimulus orientation. A small proportion of the cells are colour coded.2. Evidence is presented for at least two independent systems of columns extending vertically from surface to white matter. Columns of the first type contain cells with common receptive‐field orientations. They are similar to the orientation columns described in the cat, but are probably smaller in cross‐sectional area. In the second system cells are aggregated into columns according to eye preference. The ocular dominance columns are larger than the orientation columns, and the two sets of boundaries seem to be independent.3. There is a tendency for cells to be grouped according to symmetry of responses to movement; in some regions the cells respond equally well to the two opposite directions of movement of a line, but other regions contain a mixture of cells favouring one direction and cells favouring the other.4. A horizontal organization corresponding to the cortical layering can also be discerned. The upper layers (II and the upper two‐thirds of III) contain complex and hypercomplex cells, but simple cells are virtually absent. The cells are mostly binocularly driven. Simple cells are found deep in layer III, and in IV A and IV B. In layer IV B they form a large proportion of the population, whereas complex cells are rare. In layers IV A and IV B one finds units lacking orientation specificity; it is not clear whether these are cell bodies or axons of geniculate cells. In layer IV most cells are driven by one eye only; this layer consists of a mosaic with cells of some regions responding to one eye only, those of other regions responding to the other eye. Layers V and VI contain mostly complex and hypercomplex cells, binocularly driven.5. The cortex is seen as a system organized vertically and horizontally in entirely different ways. In the vertical system (in which cells lying along a vertical line in the cortex have common features) stimulus dimensions such as retinal position, line orientation, ocular dominance, and perhaps directionality of movement, are mapped in sets of superimposed but independent mosaics. The horizontal system segregates cells in layers by hierarchical orders, the lowest orders (simple cells monocularly driven) located in and near layer IV, the higher orders in the upper and lower layers.
The dependence of calcium efflux from cardiac muscle on temperature and external ion composition
Authors: Reuter H. , Seitz N. 
Published: December 2014

1. Exchangeable Ca in guinea‐pig auricles and ventricular trabeculae of sheep and calf hearts was labelled with 45Ca and the loss of radioactivity into inactive rinsing solutions of different ion composition was measured for periods up to 6 hr. At no time did the decrease of radioactivity in the muscle follow a single exponential course, while the rate coefficient k (= fraction of 45Ca lost per minute from muscle into rinsing solution) decreased slightly with time.2. On the basis of the temperature‐sensitivity of Ca efflux from auricles the activation energy has been calculated to have a value of 5900 cal/mole, corresponding to a Q10 of 1·35. 2,4‐Dinitrophenol (5·5 × 10−5 ‐ 5·5 × 10−4
M) had either no effect on Ca efflux or increased it slightly.3. Compared to control efflux in 1·8 m
M [Ca]o Ca efflux decreased to 70% in Ca‐free solution, to 20% in Ca‐free, Na‐free solution and to 65% in Ca‐containing, Na‐free solution, NaCl being replaced by either sucrose or LiCl. Quantitatively, Ca efflux from auricles has been shown to depend to a large extent on the ratio [Ca2+]o/[Na+]o2. The affinity for Na of the activation site for Ca efflux (carrier) is much less than for Ca.4. The efflux from muscles soaked for about 2 hr in Ca‐free solution was not linearly related to Ca‐concentration in the tissue but followed a square law.5. While Ca content in auricles increased in Ca‐containing, Na‐poor solution it decreased again when Tyrode solution was readmitted indicating a Na‐sensitive Ca net transport in cardiac muscle.6. The results are interpreted in terms of a modified exchange diffusion mechanism (Ussing, 1947) which is responsible for Ca extrusion from mammalian cardiac muscle.
The contrast sensitivity of the colour mechanisms of the human eye
Authors: Green Daniel G. 
Published: December 2014

1. To isolate the colour receptive systems of the eye, a sinusoidal grating of one colour was superimposed on a bright background of another colour and the threshold contrast for resolving the grating was determined.2. A procedure is described which allows one to estimate the extent by which the bright background reduces the contrast of the test grating of another colour. Using this procedure, the measured threshold contrasts of the test grating were replotted in terms of the effective contrast sensitivity for the composite target.3. The effectivity of a red background in reducing the contrast of a green grating was found to be determined not by its apparent brightness but rather by the extent to which it excited the green mechanism.4. The effective contrast sensitivities for a green grating on a green background, for a green grating on a red background, and for a red grating on a green background were found to be not significantly different.5. Visual acuity for a blue grating on a yellow background was reduced from normal by about a factor of six. This loss in visual acuity was due to both a reduction in contrast sensitivity and a reduction in resolution.
Responses to single photons in visual cells of Limulus
Authors: Borsellino A. , Fuortes M. G. F. 
Published: December 2014

1. A system proposed in a previous article as a model of responses of visual cells has been analysed with the purpose of predicting the features of responses to single absorbed photons.2. As a result of this analysis, the stochastic variability of responses has been expressed as a function of the amplification of the system.3. The theoretical predictions have been compared to the results obtained by recording electrical responses of visual cells of Limulus to flashes delivering only few photons.4. Experimental responses to single photons have been tentatively identified and it was shown that the stochastic variability of these responses is similar to that predicted for a model with a multiplication factor of at least twenty‐five.5. These results lead to the conclusion that the processes responsible for visual responses incorporate some form of amplification. This conclusion may prove useful for identifying the physical mechanisms underlying the transducer action of visual cells.
The distribution of monosynaptic excitation from the pyramidal tract and from primary spindle afferents to motoneurones of the baboon's hand and forearm
Authors: Clough J. F. M. , Kernell D. , Phillips C. G. 
Published: December 2014

1. Intracellular records were obtained from motoneurones innervating muscles of the baboon's forearm and hand. Monosynaptic excitatory postsynaptic potentials (EPSPs) were elicited by stimulation of motor cortex (CM EPSPs) and peripheral nerves (Ia EPSPs).2. CM EPSPs were larger on average in motoneurones innervating intrinsic hand muscles and extensor digitorum communis (EDC) than in neurones of other forearm muscles.3. Among motoneurones of the median nerve, the CM EPSP tended to be larger for cells with more rapidly conducting axons than for those with more slowly conducting axons. Among motoneurones of EDC the opposite tendency was found.4. The afferent fibres responsible for the Ia EPSP nearly always had a lower stimulus threshold than that of motor axons in the same nerve. Some observations were made concerning the distribution of heteronymous Ia EPSPs.5. Among motoneurones of a given nerve, those with large Ia EPSPs tended to receive larger CM EPSPs than did cells in which the Ia EPSP was small.6. The results are discussed in relation to problems concerning the pyramidal control of hand and finger movement.
Outward membrane currents activated in the plateau range of potentials in cardiac Purkinje fibres
Authors: Noble D. , Tsien R. W. 
Published: December 2014

1. The membrane currents in Purkinje fibres under voltage clamp conditions have been investigated in the range of potentials at which the action potential plateau occurs. The results show that in this range slow outward current changes occur which are quite distinct from the potassium current activated in the pace‐maker range of potentials.2. The time course of current change in response to step voltage changes is non‐exponential. At each potential the current changes may be analysed in terms of the sum of two exponential changes and this property has been used to dissect the currents into two components, ix1 and ix2, both of which have been found to obey kinetics of the Hodgkin—Huxley type.3. The first component, ix1, is activated with a time constant of about 0·5 sec at the plateau. At more positive and more negative potentials the time constants are shorter. The steady‐state degree of activation varies from 0 at about ‐50 mV to about 1 at +20 mV. The instantaneous current—voltage relation is an inward‐going rectifier but shows no detectable negative slope. In normal Tyrode solution ([K]0 = 4 m
M) the reversal potential is about ‐85 mV.4. The second component, ix2, is activated extremely slowly and the time constant at the plateau is about 4 sec. The steady‐state activation curve varies from 0 at about ‐40 mV to 1 at about +20 mV. The instantaneous current—voltage relation is nearly linear. The reversal potential occurs between ‐50 and ‐20 mV in different preparations.5. It is suggested that these currents are carried largely by K ions, but that some other ions (e.g. Na) also contribute so that the reversal potentials are positive to EK.6. The relation of these results to previous work on delayed rectification in cardiac muscle is discussed.
Strontium and quantal release of transmitter at the neuromuscular junction
Authors: Dodge F. A. , Miledi R. , Rahamimoff R. 
Published: December 2014

1. Previous work has shown that in calcium‐free solutions nerve impulses invade the motor nerve terminals at the neuromuscular junction, but fail to release transmitter. In these conditions, strontium ions applied iontophoretically to a minute part of a junction, or to the whole muscle by bath application, restore to the nerve impulse its ability to release transmitter.2. As with calcium, the transmitter released in the presence of strontium is in the form of packages (quanta) whose release can be predicted from Poisson's Theorem.3. The mean number of quanta released by a nerve impulse increases with the concentration of strontium. Strontium is much less effective than calcium in equimolar concentrations.4. Transmitter quanta released in the presence of strontium evoke larger unit potentials than quanta released in the presence of calcium. The larger size of the Sr‐unit potentials is caused by a prolongation of transmitter action, presumably due to a post‐synaptic effect of strontium.5. Neuromuscular transmission was blocked in some fibres when the concentration of strontium was raised beyond 10 m
M. This junctional block was presumably due to a failure in the propagation of nerve impulses.6. The post‐stimulation increase in the frequency of miniature end‐plate potentials, which is normally seen in calcium solutions, is also observed when calcium is substituted by strontium. The post‐stimulation effect increases with the concentration of strontium.7. It is concluded that strontium can substitute for calcium in the process of quantal release of transmitter. The physico‐chemical mechanism of this substitution remains unknown.
Projection to cerebral cortex of Group I muscle afferents from the cat's hind limb
Authors: Landgren S. , Silfvenius H. 
Published: December 2014

1. Muscle afferent projections from the contralateral hind limb to the postsigmoid gyrus of the cerebral cortex were investigated in cats anaesthetized with chloralose. The evoked potentials were recorded from the cortical surface or from deeper layers by penetrating micro‐electrodes. Graded electrical stimulation of the nerves was used.2. Group Ia as well as Ib muscle afferents from the contralateral quadriceps, posterior biceps‐semitendinosus, gastrocnemius‐soleus and deep peroneal muscles projected to two different loci in the postsigmoid gyrus. One of these was located on the dorsal surface of the hemisphere 4‐5 mm lateral to the mid line and 1‐3 mm posterior to the cruciate sulcus, thus rostro‐medial to the postcruciate dimple. The other was located on the medial surface of the hemisphere adjacent to the cruciate sulcus. There was no overlap between the two loci.3. There was no significant difference in thresholds or latencies of the Group I responses in the two loci. The latency was short and similar to that of the potential evoked by the cutaneous afferents in the somatosensory primary projection areas.4. The Group Ib path was largely independent of the Ia path, because a maximal Group I volley evoked a response, when the Ia path was made refractory by simultaneous stimulation with a maximal Ia volley at 20 per second.5. The cortical potentials evoked by the Group I muscle afferents from the contralateral hind limb did not change after transection of the dorsal columns at C1‐C3 levels but disappeared after a superficial section in the dorsolateral fascicle at C1 level. The responses were not affected by cerebellectomy. It was concluded that the path travelled with the dorsal spinocerebellar tract or utilized brain stem collaterals of this tract.6. Group II muscle afferents evoked a response near the border of the Group I loci, but not in the positions where the Group I responses were maximal in amplitude.7. The receptor origin of the stimulated Group I afferents, the location of the medullary relay in the Group I path and the destination of the efferent outflow from the Group I loci were discussed.