RESUMEN
BACKGROUND: In the United Kingdom, totally implantable venous access systems (TIVAS) are not routinely used. Compared with Hickman catheters, these devices are more expensive and complex to insert. However, it is unclear whether the higher costs may be offset by perceived greater health benefits. This pilot trial aimed to generate relevant data to inform the design of a larger definitive randomised controlled trial. METHODS: This was a phase II prospective, randomised, open trial from two UK oncology centres. The primary end point was overall complication rate. Secondary end points included individual complication rates, time to first complication and quality of life. Analysis was by intention to treat. An economic evaluation was also carried out. RESULTS: A total of 100 patients were randomised in a 3 : 1 ratio to receive a Hickman or a TIVAS. Overall, 54% of patients in the Hickman arm suffered one or more complications compared with 38% in the TIVAS arm (one-sided P=0.068). In the Hickman arm, 28% of the devices were removed prematurely due to a complication compared with 4% in the TIVAS arm. Quality of life based on the device-specific questionnaire was greater in the TIVAS arm for 13 of the 16 questions. The economic evaluation showed that Hickman arm was associated with greater mean cost per patient £1803 (95% CI 462, 3215), but similar quality-adjusted life years -0.01 (95% CI -0.15, 0.15) than the TIVAS arm. However, there is much uncertainty associated with the results. CONCLUSIONS: Compared with Hickman catheters, TIVAS may be the cost-effective option. A larger multicentre trial is needed to confirm these preliminary findings.
Asunto(s)
Cateterismo Venoso Central/métodos , Sistemas de Liberación de Medicamentos/métodos , Quimioterapia/métodos , Cateterismo Venoso Central/economía , Análisis Costo-Beneficio , Sistemas de Liberación de Medicamentos/economía , Quimioterapia/economía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios ProspectivosRESUMEN
Intracellular electrophysiological studies of lateral protocerebral interneurons (LPIs) in the crayfish Procambarus clarkii have revealed convergence of multimodal sensory information onto these higher-level cells of the crustacean central olfactory pathway. Antennular stimulation by odors or electrical shocks generates excitatory-inhibitory sequences in some LPIs as does electrical or hydrodynamic stimulation of the antennae. Photic stimulation of the ipsilateral compound eye generates excitatory responses in LPIs, usually in the form of trains of impulse bursts that are timed to the peaks of the spontaneous oscillatory activity that characterizes these neurons. Focal electrical stimulation of the olfactory lobe, the termination point of antennular afferent input, or the accessory lobe, where higher-level visual and tactile inputs converge, also generates brief excitation and a delayed, prolonged inhibition in LPIs. Both phases of this activity are thought to be transmitted to the lateral protocerebrum via deutocerebral projection neurons, which have extensive dendritic arborizations in the olfactory lobe and the accessory lobe. The excitatory pathway is thought to synapse directly with target LPIs, whereas the inhibitory pathway is probably indirect and mediated through GABAergic interneurons within the lateral protocerebrum. There is evidence that both presynaptic and postsynaptic inhibition suppress activity in LPIs. Preliminary observations suggest that a small cluster of neurons adjacent to the hemi-ellipsoid body are inhibitory to LPI activity. Multimodal inhibitory and excitatory modulation of LPI activity may play a part in the contextual identification of odors in the crayfish olfactory system.
Asunto(s)
Astacoidea/fisiología , Neuronas/fisiología , Vías Olfatorias/fisiología , Potenciales de Acción/fisiología , Animales , Sistema Nervioso Central/fisiología , Estimulación Eléctrica , Modelos Neurológicos , Inhibición Neural/fisiología , Neuronas/citología , Neuronas Receptoras Olfatorias/citología , Neuronas Receptoras Olfatorias/fisiología , Estimulación Luminosa , Tiempo de Reacción/fisiología , Estimulación QuímicaRESUMEN
Posthatch larval crayfish (Procambarus clarkii) were unilaterally antennulectomized and maintained in the laboratory for a 6-month period, during which time all regenerating antennular stumps were periodically excised. In another group of animals at a similar developmental stage a heteromorphic antennule was induced on the side of the head ipsilateral to the chronically sectioned normal antennule. After 6 months, all experimental animals were sacrificed and their brains were fixed and sectioned. Computer-aided quantitative measurements were obtained for the volumes of the olfactory lobes on both the experimental and control sides of the brains of both groups of crayfish. In the brains of the crayfish group in which only chronic antennualectomy had been performed, the olfactory lobe ipsilateral to the lesion was reduced in volume by about 80% compared to the olfactory lobe on the control side. In animals in which the normal antennule had been chronically ablated, but which possessed a heteromorphic antennule on the same side, the olfactory lobe on the lesioned side differed in volume from the control side by a mean value of only 28%. We conclude that afferent fibers from a heteromorphic antennule ipsilateral to a chronically lesioned normal antennule can assume some of the central trophic functions of the afferents from the normal antennule; thus, the presence of a heteromorphic antennule offers some measure of protection from the dystrophic effects of chronic ablation of the normal antennule during development and growth in crayfish.
Asunto(s)
Astacoidea/fisiología , Mesencéfalo/fisiología , Bulbo Olfatorio/fisiología , Órganos de los Sentidos/fisiología , Animales , Larva/fisiología , Mesencéfalo/anatomía & histología , Bulbo Olfatorio/anatomía & histología , Órganos de los Sentidos/anatomía & histologíaRESUMEN
Lateral protocerebral interneurons (LPIs) in the central olfactory pathway of the freshwater crayfish Procambarus clarkii reside within the lateral protocerebrum and receive direct input from projection neurons of the olfactory midbrain. The LPIs exhibit periodic (0.5 Hz) changes in membrane potential that are imposed on them synaptically. Acute surgical experiments indicate that the synaptic activity originates from a group of oscillatory neurons lying within the lateral protocerebrum. Simultaneous intracellular recordings from many LPI pairs indicate that this periodic synaptic input is synchronous and coherent among the population of approximately 200 LPIs on each side of the brain. In many LPIs, specific odors applied to antennules in isolated head preparations generate long-lasting excitatory postsynaptic potentials and impulse bursts. The impulse bursts are generated only near the peaks of the ongoing depolarizations, approximately 1 s after stimulus application, and so the periodic baseline activity is instrumental in timing burst generation. Simultaneous recordings from pairs of LPIs show that, when impulse bursts occur in both cells after an odorant stimulus, they are synchronized by the common periodic depolarizations. We conclude that the common, periodic activity in LPIs can synchronize impulse bursts in subsets of these neurons, possibly generating powerful long-lasting postsynaptic effects in downstream target neurons.
Asunto(s)
Sincronización Cortical , Neuronas Receptoras Olfatorias/fisiología , Animales , Astacoidea , Estimulación Eléctrica , Interneuronas/fisiología , Potenciales de la Membrana/fisiología , OscilometríaRESUMEN
NADPH-d histochemistry was used to investigate presumptive nitric oxide synthase (NOS)-containing neurons in the crayfish olfactory midbrain. Three anatomically different types of local olfactory interneurons exhibiting NADPH-d activity were observed: two pairs of large interneurons as well as positively stained globuli cells. Branches derived from the large interneurons were confined to the ipsilateral olfactory lobe and accessory lobe, but only a few branches innervated the olfactory lobe glomeruli. Local field potential recordings on the olfactory lobe showed that administration of SNP or SIN-1 (10-4 M) into the brain had reversible inhibitory effects on electrically-evoked responses of unidentified neuronal cell populations.
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Mesencéfalo/fisiología , Óxido Nítrico/fisiología , Bulbo Olfatorio/fisiología , Sistemas de Mensajero Secundario/fisiología , Animales , Astacoidea , Femenino , Inmunohistoquímica , Interneuronas/enzimología , Masculino , Mesencéfalo/citología , NADP/análisis , Óxido Nítrico Sintasa/análisis , Bulbo Olfatorio/citologíaRESUMEN
An AIDS patient was seen in respiratory difficulty with a superior mediastinal mass. Examination revealed a candida fungoma. To the best of our knowledge, this is the only case of its nature. The differential diagnosis and management of this patient are presented in detail.
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Síndrome de Inmunodeficiencia Adquirida/complicaciones , Enfermedades de la Tráquea/etiología , Adulto , Candida albicans/aislamiento & purificación , Humanos , Masculino , Ventilación Pulmonar , Ruidos Respiratorios , Enfermedades de la Tráquea/microbiología , Enfermedades de la Tráquea/fisiopatologíaRESUMEN
Little knowledge is available concerning the detailed anatomy of the crusctacean central olfactory pathway. We are using radiolabeling, Golgi and biocytin/neurobiotin tracer methodologies, at the correlated light and electron microscopical levels, to study the olfactory midbrain of the freshwater crayfish. We have found that primary afferent fibers from the antennular olfactory receptor cells branch extensively throughout the length of the glomerular columns within the olfactory lobes in the midbrain. Globuli cells of the lateral cell clusters ramify as dendritic arborizations within both the olfactory and accessory lobes; their axons project out the olfactory-globular tracts to the lateral protocerebrum, often branching to both sides. Developmental plasticity involving the connections made by afferent fibers within the olfactory lobes may permit detailed examination of organizational changes within the midbrain as the animal grows and adds new afferent input from the periphery.
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Astacoidea/anatomía & histología , Plasticidad Neuronal , Vías Olfatorias/ultraestructura , Vías Aferentes/ultraestructura , Animales , Axones/ultraestructura , Biotina/análogos & derivados , Lisina/análogos & derivados , Mesencéfalo/ultraestructuraRESUMEN
Golgi impregnation and neurobiotin injection were used to examine details of the neural pathways in the olfactory system of the freshwater crayfish, Procambarus clarkii. Deutocerebral projection neurons (globuli cells) were directly injected with neurobiotin. These neurons have dendritic arborizations in the ipsilateral olfactory and accessory lobes, and they project axons to the lateral protocerebrum, where they terminate in microglomeruli of the hemi-ellipsoid body. The axons of the deutocerebral projection neurons are readily impregnated by Golgi procedures, and they terminate as an expanded membranous knot about 5 microns in diameter. Electron microscopy on Golgi-stained terminals has revealed that each knot makes several hundred synapses with small spine-like or shaft-like processes of postsynaptic neurons. Injection of neurobiotin into local interneurons of the hemi-ellipsoid body and subsequent examination of stained preparations with the electron microscope reveals that these cells are a major postsynaptic target of the deutocerebral projection neurons. Furthermore, the local interneurons make extensive efferent synaptic connections with unidentified neurons in the terminal medulla.
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Astacoidea/anatomía & histología , Neuronas/citología , Animales , Simulación por Computador , Aparato de Golgi/ultraestructura , Microscopía Electrónica , Modelos Anatómicos , Modelos Neurológicos , Neuronas/ultraestructura , Vías Olfatorias/anatomía & histología , Vías Olfatorias/citología , Vías Olfatorias/ultraestructura , Coloración y Etiquetado , Sinapsis/ultraestructuraRESUMEN
Myxedema results from hypofunction of the thyroid gland. Symptoms include dry skin, loss of and dryness of hair, mental apathy, drowsiness, and sensitivity to cold. Ocular complications associated with myxedema may be the symptoms that first prompt patients to seek a physician or cosmetic surgeon, however, though other symptoms may be present before eyelid myxedema occurs. The case reported here illustrates the value of a correct diagnosis and appropriate medical treatment, and demonstrates how surgical intervention to correct remaining eyelid problems can succeed when it is part of a comprehensive treatment plan.
Asunto(s)
Mixedema/cirugía , Párpados/cirugía , Humanos , Masculino , Persona de Mediana Edad , Cirugía Plástica , Colgajos QuirúrgicosRESUMEN
We have used tritiated leucine to trace the input projection pattern of olfactory sensory neurons in crayfishes. The olfactory neurons are associated with cuticular sensilla on the external antennular filaments. Each sensillum, or aesthetasc, harbors the distal dendritic segments of about 175 bipolar sensory neurons, the cell bodies for which are grouped in a subcuticular ensemble or ganglion. About 150-175 individual ganglia may be found on each antennule in an adult crayfish. When an aesthetasc is exposed to tritated leucine, the tracer is taken up by the associated olfactory sensory neurons and is transported along the axons to their central terminations within the glomeruli of the ipsilateral olfactory lobe. We tested the possibility that the sensory neurons from specific aesthetascs project to specific glomeruli. By restricting access of the leucine to small groups of aesthetascs, we exposed less than 2% of the olfactory sensory neurons to the tracer. Nonetheless, all glomeruli were labeled following such treatment. We conclude that the sensory neurons are generally distributed to the olfactory glomeruli. If each neuron terminates in a single glomerulus, these data support a divergent pattern of sensory projection from individual ganglia to all regions of the olfactory lobe.
Asunto(s)
Astacoidea/anatomía & histología , Sistema Nervioso Central/anatomía & histología , Neuronas Aferentes/citología , Vías Olfatorias/anatomía & histología , Animales , Astacoidea/fisiología , Leucina/farmacocinética , Vías Olfatorias/fisiologíaRESUMEN
Surgical excision of one of the compound eyes from juvenile crayfish leads to the regeneration of a heteromorphic antennule in 30% of the cases. Most of the heteromorphic antennules generated this way are bifurcate appendages possessing morphologically distinct medial and lateral branches. These structures are identical to the internal and external flagella of the normal antennules, and the homolog of the external flagellum bears aesthetascs supplied by olfactory sensory neurons. Autoradiographic analysis of the brain following exposure of heteromorphic antennules to tritiated leucine indicates that the supernumerary sensory axons transport the labeled amino acid into their central terminals at appropriate target locations within the ipsilateral olfactory lobe. The data suggest that olfactory input from heteromorphic antennules is incorporated into the organized central projection of olfactory afferents from the normal antennule.
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Astacoidea/metabolismo , Leucina/farmacocinética , Neuronas Aferentes/metabolismo , Bulbo Olfatorio/metabolismo , Animales , Autorradiografía , Microscopía Electrónica , Neuronas Aferentes/ultraestructura , Bulbo Olfatorio/citología , Vías Olfatorias/citología , Vías Olfatorias/metabolismoRESUMEN
We have performed surgical transections on nerves in the transforming claws of snapping shrimps. In normal transformation muscle restructuring occurs, involving degeneration of some fibers and biochemical changes in others. Surgical section of the entire second limb nerve root or of its distal, dorsal branch--both of which contain the motor axons to the closer muscle--prevents muscle restructuring, even though transformation of external claw morphology proceeds. Furthermore, nerve lesions must be performed within a specific time period after transformation has been triggered in order for the effects to be observed. We suggest that transformation involves an early sensitization of the targeted muscle and that this process depends upon an intact nervous pathway within the second nerve root.
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Decápodos/fisiología , Extremidades/inervación , Músculos/fisiología , Unión Neuromuscular/fisiología , Nervios Periféricos/fisiología , Potenciales de Acción , Animales , Estimulación Eléctrica , Extremidades/fisiología , Potenciales de la Membrana , Músculos/inervación , RegeneraciónRESUMEN
Isotopes of a number of crustacean myofibrillar proteins have been identified with sodium dodecyl sulfate-polyacrylamide electrophoresis, and their distribution in muscles of the snapping shrimp has been examined. Fast-slow differences in distribution have been observed for myosin light chains and tropomyosin. In contrast, three troponin T subunits have been resolved, each specific to one of the three muscles examined. This result suggests that expression of crustacean contractile proteins is not accomplished by a simple coexpression of a battery of slow or fast isotopes. In addition, the expression of these proteins was examined during the quasi-developmental fiber-type transition of the main claw closer muscle during the reversal of claw asymmetry in response to the loss of the large snapper appendage. The changes observed appear similar to the cross-innervation induced changes in gene expression of vertebrate muscle.
Asunto(s)
Regulación de la Expresión Génica , Músculos/citología , Animales , Diferenciación Celular , Decápodos , Electroforesis en Gel de Poliacrilamida , Proteínas Musculares/análisis , Proteínas Musculares/genéticaRESUMEN
During growth of identified crayfish muscle fibres from a diameter of 20 to 400 micron, the excitatory junctional potential (e.j.p.) amplitude was found to be independent of diameter. Thus, e.j.p. amplitude was maintained during growth in spite of a 21-fold decrease in miniature excitatory junctional potential (m.e.j.p.) amplitude previously reported (Lnenicka & Mellon, 1983). The maintenance of e.j.p. amplitude was found to be partially due to a 5-fold increase in quantal release at 'active sites' during growth. In order to determine whether the increase in transmitter release can be regulated by the rate of muscle fibre growth, the rate of growth was experimentally reduced. By decreasing the resting length of the muscle during growth, the rate of increase in the diameter was reduced by approximately 50% compared with the contralateral control muscle fibres. The input resistance and the m.e.j.p. were appropriately larger in the smaller-diameter experimental fibres. However, e.j.p. amplitude in the experimental fibres was not significantly different from that in the contralateral control fibres. This was apparently due to the significantly smaller quantal release at active sites on the experimental fibres compared with control fibres. Thus, experimental alteration of the rate of muscle fibre growth results in regulation of transmitter release, suggesting that the muscle fibre may control the increase in transmitter release seen during normal growth.
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Astacoidea/fisiología , Músculos/fisiología , Neurotransmisores/metabolismo , Potenciales de Acción , Animales , Axones/fisiología , Conductividad Eléctrica , Desarrollo de Músculos , Unión Neuromuscular/fisiología , Sinapsis/metabolismo , Sinapsis/fisiología , Transmisión SinápticaRESUMEN
The muscle fibre electrical properties, miniature excitatory junctional current (m.e.j.c.) and miniature excitatory junctional potential (m.e.j.p.) were studied during growth of an identified crayfish muscle fibre from a diameter of 20 to 400 microns. The specific membrane resistance (Rm), and the specific internal resistance (Ri), of the muscle fibre were independent of fibre diameter (d) during growth. The current-voltage relation has a similar shape in large and small fibres, indicating that voltage dependence of Rm does not change during growth. The input resistance (R0) was approximately proportional to d-1.5, as predicted theoretically. The specific membrane capacitance (Cm) and the membrane time constant (Tm) increased linearly with fibre diameter, apparently as a result of the contribution of the tubular capacitance to Cm. The decrease in R0 and the increase in Tm should have resulted in a 90-fold decrease in m.e.j.p. amplitude during growth of the fibre from a diameter of 20 to 240 microns. However, m.e.j.p. amplitude was found to decrease only 21-fold. This discrepancy was shown to result from an increase in m.e.j.c. amplitude and duration during growth. There was 2.9-fold increase in m.e.j.c. amplitude and a 2.7-fold increase in m.e.j.c. duration over the range of muscle fibre growth studied. This increase in the m.e.j.c. apparently results from an increase in the magnitude and duration of the synaptic conductance change produced by a quantum of transmitter. Throughout the range of muscle fibre diameters studied, the muscle fibre effective input impedance for the m.e.j.c. was 17-19% of R0. This is due to the relatively large Cm and the short duration of the m.e.j.c.
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Astacoidea/fisiología , Músculos/fisiología , Potenciales de Acción , Animales , Axones/fisiología , Conductividad Eléctrica , Desarrollo de Músculos , Unión Neuromuscular/fisiología , Sinapsis/fisiología , Factores de TiempoRESUMEN
We compared the neuromuscular junctions on the main closer muscle in the first pair of chelipeds in the snapping shrimp Alpheus heterochelis by serial section electron microscopy. We sought an ultrastructural basis for the different behavioral and physiological functions of these dimorphic claws and for the role of the nervous system in claw transformation. We were unable to detect any statistically significant morphological differences between the junctions. Further, we found the muscle fiber populations and filament arrangements, as well as the electrical properties of the fibers, to be more homogeneous and similar to each other in A. heterochelis than those reported for another species, A. armillatus. We consider our results in light of recent data on the anatomy and electrical properties of the motor neurons within the CNS and conclude that the neural trigger for claw transformation involves factors not revealed by conventional electron microscopy.
Asunto(s)
Decápodos/anatomía & histología , Unión Neuromuscular/ultraestructura , Animales , Miembro Anterior/inervación , Cuerpos de Inclusión/ultraestructura , Microscopía Electrónica , Contracción Muscular , Sinapsis/ultraestructura , Vesículas Sinápticas/ultraestructuraRESUMEN
Cell bodies of claw closer motor neurons in snapping shrimp are dimorphic. Snapper claw motor neurons are larger than corresponding pincer claw motor neurons, but the relative sizes of these cells are reversed during claw transformation. An additional neuronal modification occurs early within this period, in that the pincer claw dorsal inhibitor cell body migrates within the nervous system, from a dorsal to a ventral position. These findings are evidence of rapid, reversible changes in the nervous system following the trigger for the transformation process.
Asunto(s)
Sistema Nervioso Central/anatomía & histología , Decápodos/anatomía & histología , Neuronas Motoras/fisiología , Animales , Axones/fisiología , Conductividad Eléctrica , Potenciales Evocados , Ganglios/anatomía & histología , Neuronas Motoras/citologíaRESUMEN
The morphologies and passive electrical parameters of fibres in two eye muscles of a surface- and a cave-dwelling crayfish were compared. In the cave-dwelling form the muscles contained fewer fibres, of less diameter, and hence had a smaller cross-sectional area. Current-voltage relationships were similar in both species. Input resistance was higher in the cave-dweller, but the difference was not as great as would be expected on the basis of geometry alone. Accordingly, the specific membrane resistance of muscle fibres in the cave-dweller is 50-60% smaller than that in the surface-dweller. This may account partially for the observation that identified excitatory junctional potentials in muscles of cave- and surface dwellers have similar amplitudes. We conclude that a functional oculomotor system is maintained in cave-dwelling crayfish, and that this system confers some positive selective advantage.
Asunto(s)
Astacoidea/fisiología , Oscuridad , Músculos Oculomotores/anatomía & histología , Adaptación Fisiológica , Animales , Astacoidea/anatomía & histología , Ambiente , Ojo/anatomía & histología , Potenciales de la Membrana , Músculos Oculomotores/fisiologíaRESUMEN
Intracellular recordings demonstrated a transfer of impulses between the paired giant axons of Sabella, apparently along narrow axonal processes contained within the paired commissures which link the nerve cords in each segment of the body. This transfer appears not to be achieved by chemical transmission, as has been previously supposed. This is indicated by the spread of depolarizing and hyperpolarizing voltage changes between the giant axons, the lack of effects of changes in the concentrations of external divalent cations on impulse transmission and by the effects of hyperpolarization in reducing the amplitude of the depolarizing potential which precedes the action potentials in the follower axon. The ten-to-one attenuation of electronic potentials between the giant axons argues against the possibility of an exclusively passive spread of potential along the axonal processes which link the axons. Observation of impulse traffic within the nerve cord commissures indicates, on the other hand, that transmission is achieved by conduction of action potentials along the axonal processes which link the giant axons. At least four pairs of intact commissures are necessary for inter-axonal transmission, the overall density of current injected at multiple sites on the follower axon being, it is presumed, sufficient to overcome the reduction in safety factor imposed by the geometry of the system in the region where axonal processes join the giant axons. The segmental transmission between the giant axons ensures effective synchronization of impulse traffic initiated in any region of the body and, thus, co-ordination of muscular contraction, during rapid withdrawal responses of the worm.