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PubMed1985

Sensory neuron growth cones comigrate with posterior lateral line primordial cells in zebrafish.

The development of neuromasts and sensory neurons of the posterior lateral line was studied in zebrafish (Brachydanio rerio) in order to determine the relationship between growing axons of sensory neurons and the migratory cellular primordium of midbody line neuromasts. Scanning electron microscopy revealed that a primary system of six neuromasts develops during the second day after fertilization and evidence is presented that these arise from cells of a migratory primordium. The primordium is first detected in the postauditory region immediately adjacent to the developing sensory ganglion. Growth cones of posterior lateral line sensory neurons are found within the premigratory primordium when it is adjacent to the ganglion. At later times growth cones of these sensory neurons are found within the primordium as it migrates caudally along the midbody line. These results demonstrate that although the growth cones of the sensory neurons grow over a considerable distance to their final destination, they are never very far from their target cells (or target cell precursors), which migrate with them and may even lead them.

Animals↗
PubMed1985

Projection systems and terminal localization of dorsal column afferents: an autoradiographic and horseradish peroxidase study in the rat.

Projection systems from the gracile nucleus and the cuneate nuclear complex to their terminal sites in the mesencephalon, diencephalon, and cerebellum were examined by means of anterograde autoradiography and retrograde horseradish peroxidase methods. Three projection systems emerge from the dorsal column nuclei, decussate via internal arcuate fibers, and form the contralateral medial lemniscus (ML). At the obex, some fibers split off the ML and course dorsolaterally, forming an ascending lateral system which fits the "lemniscal adjunct channel" (LAC) concept of Graybiel ('72). The ML continues rostrally as the "main lemniscal line channel" (MLLC). At the inferior colliculus, some LAC fibers terminate in the pontine nuclei, parabrachial, dorsal reticular nuclei, and the external and ventral medial part of the central nucleus of the inferior colliculus. More rostrally at the level of the superior colliculus, terminal fields are found in the medial nucleus of the medial geniculate body, the suprageniculate, pretectal, and mesencephalic reticular nuclei, marking the end of the LAC. In the diencephalon, gracile fibers leave the MLLC and form a crescentlike terminal field along the extreme lateral border of the ventral posterior lateral nucleus (VPL) of the thalamus. Cuneate MLLC fibers terminate in a bandlike formation in the VPL medial to the gracile termination. The third fiber system, the cuneocerebellar projection, emerges from the cuneate, the external cuneate nuclei, and the "cellular bridge" and immediately enters the ipsilateral inferior cerebellar peduncle. Upon entering the cerebellum, the major fiber component remains ipsilateral and terminates as vertical bands in vermal and paravermal lobules, and lobules I through IVa. The posterior cerebellar lobe contains terminal bands in lobules VII-IX, the copula pyramidis, and the paramedian lobule. It is concluded that the dorsolateral fiber system conforms to Graybiel's LAC. It is more divergent and probably less modality specific, whereas the medial lemniscal system conforms to the MLLC, which is said to be modality specific, less divergent, and locked to specific sensory-motor response characteristics. The topography of cerebellar terminal bands indicates that there is sensory-motor representation from all parts of the body to all parts of the cerebellum, at least in the rat.

Afferent Pathways↗
PubMedDate not supplied

Identification of antibodies to nuclear acidic antigens by counterimmunoelectrophoresis.

Saline extracts of rabbit thymus were found to contain many nuclear antigens that reacted with antibodies in the sera of patients with systemic rheumatic diseases. Counterimmunoelectrophoresis (CIE) was used to detect antibodies to nuclear acidic protein (Sm), nuclear ribonucleoprotein (RNP), and antibody to nuclear antigen B, which was reported previously in Sjögren's syndrome. All these nuclear antigens behaved as anions with different mobilities in CIE and could be distinguished from one another by the locations of the precipitin lines. They could also be distinguished by the facts that the nuclear RNP precipitin lines were abolished by digestion with ribonuclease whereas others were unaffected, and that Sm precipitin lines developed later than other precipitin lines. With this technique antibody to nuclear RNP was detected in 46% of patients with systemic lupus erythematosus (SLE) compared to 26% detected by the hemagglutination technique. Similarly the increased sensitivity of the CIE technique was able to show that antibody to B antigen was present in 12% of SLE patients, whereas this antibody was not detectable in the same group of patients by immunodiffusion. This study shows that CIE is a rapid and sensitive technique for detecting precipitating antibodies to a number of nuclear acidic antigens. Methods are described to identify the immunochemical specificities of the precipitin lines by the use of standard reference sera.

Antibodies, Antinuclear↗
PubMed1984

Ultrastructure of fetal spinal cord and cortex implants into adult rat spinal cord.

The ultrastructure of cortex and spinal cord from 11-, 12-, and 15-day-old fetuses implanted into the spinal cord of adult rats was studied over 3 months. Under deep Chloropent anesthesia, a 0.5 X 1.0-mm square of fetal cortex or a 1.0-mm segment of fetal spinal cord was implanted subpially between the left dorsal column and the dorsal horn of 70 adult rats. Implants grew toward gray matter, usually interfacing with the host at the isthmus between the horns of the spinal cord. However, implants were observed that occupied the entire left dorsal and ventral horns of the left half of the host spinal cord. Implants had concentric zones: A central zone with basal lamina lined joined channels and subjacent neuroglia; a zone of differentiating implant nervous system; a zone with basal lamina lined implant with overlying pial cells on the dorsal and lateral surfaces of the implant; a zone that interfaced with the host with overlapping neuropil on the lateral and ventral surfaces of the implant. Neuron types were typical for cortical or spinal implants. Implants survived for 3 months and reached stages of neuronal and neuroglial maturation similar to controls. Both fetal spinal cord and brain were successful as implants, had delayed differentiation, and formed complex neuropils. The zone of overlapping interface of the donor and host is an anatomical indication of physiological and functional integration.

Animals↗
PubMed2005

Angle-splitting ostectomy followed by face lift for elderly patients with prominent mandibular angles.

A prominent mandibular angle is a relatively common aesthetic problem among Asians, and the reduction angle-splitting ostectomy is now becoming a very popular procedure in Asian countries. Although this operation is usually performed on young patients, the same aesthetic demands are also seen in the elderly. In this report, the authors describe their experience with angle-splitting ostectomies followed by face lifts in three patients older than 50 years. The angle-splitting procedure was the same as that performed in young patients, and clinical results were assessed with photographs and three-dimensional computed tomographic scans. The facial contours after angle-splitting ostectomy were satisfactory, but the patients showed postoperative redundancy of the skin, especially along the jaw line, because of the loss of bony protrusion laterally. Therefore, the patients underwent subsequent superficial musculoaponeurotic system cheek lifts. The final aesthetic results were satisfactory in all cases. When surgeons want to perform the angle-splitting ostectomy safely and effectively on the elderly, they should be aware of the risks and indications specific for elderly patients, and a multidisciplinary support system should be available. Subsequent face lifts can improve skin redundancy and lead to better cosmetic results.

Aged↗
PubMed1993

Adverse effects on sperm movement characteristics in women with minimal and mild endometriosis.

OBJECTIVE: To test the effect of peritoneal fluid from infertile women with minimal or mild endometriosis on sperm movement characteristics in comparison with fertile and infertile women with no endometriosis. DESIGN: A prospective observer-blind trial. SETTING: Academic infertility department. SUBJECTS: 57 women undergoing diagnostic laparoscopy or laparoscopic sterilisation. MAIN OUTCOME MEASURES: Changes in sperm movement characteristics in semen samples provided during routine infertility investigation or from sperm donors. Computer assisted semen analysis (CASA) performed using a Celltrack-S system. RESULTS: Significant reductions in linearity (P < 0.05), amplitude of lateral head displacement (P < 0.01), straight line velocity (P < 0.01), and curvilinear velocity (P < 0.01) (but not percentage motility) were observed. CONCLUSIONS: Peritoneal fluid from women with minimal or mild endometriosis adversely effects sperm movement characteristics in comparison to fertile women.

Adult↗
PubMed1978

Elasticity of excised dog lung parenchyma.

An experimental procedure was developed to measure the stress-strain relationship on rectangular slabs (5.0 X 5.0 X 0.5 cm) of excised dog's lung. The slabs were subjected to biaxial loading and the resulting triaxial deformations were measured. Deformations were measured in the central portion of the specimen by video dimension analysers in order to minimize boundary effects. Specimen thickness was measured with a magnetic reluctance proximeter system. The data were sampled and stored on-line by a PDP-8E computer. An electromechanical servo system was used to control the lateral force. Tests were performed at several pH values and at 20 and 37 degrees C. The tissue exhibited a highly nonlinear stress-strain relationship, compliant at low stress levels and stiff when the stress was high. Hysteresis was observed to be about 28% and was unaffected by a 250-fold change in strain rate. Biaxial loading revealed a new characteristic: there is a change in elastic behavior when the tissue undergoes a compressive strain. When the tissue was in tension increasing the lateral load decreased the compliance, but the opposite was true when compressive strain was present.

Animals↗
PubMed1995

Thallium poisoning presenting with abdominal colic, paresthesia, and irritability.

A case of acute thallium poisoning presenting with sudden abdominal pain, paraesthesiae and irritability is described. The peripheral nervous system was later affected along with loss of hair and the development of streaks (Mee's lines) on the nails of the hands and feet. The diagnosis was established by thallium assays of blood and urine. Thallium was undetectable in the blood by day 70. The manifestations cleared in six months with symptomatic treatment only. We review the characteristics and differential diagnosis of thallium poisoning and stress the importance of a high index of clinical suspicion.

Adult↗
PubMed1987

Control of isotubulin expression during neuronal differentiation of mouse neuroblastoma and teratocarcinoma cell lines.

Mouse neuroblastoma and teratocarcinoma constitute adequate cellular systems to study the expression of tubulin isoforms during early as well as later steps of neuronal differentiation. Tubulin heterogeneity is extensively analyzed using both isoelectric focusing and two-dimensional electrophoresis. Multipotential embryonal carcinoma cells express mainly one alpha-tubulin isoform (alpha 1) and three beta-tubulin isoforms: a major one (beta 3) and two minor ones (beta 4 and beta 5). Early events of neuronal differentiation are shown to induce the expression of an additional beta-tubulin isoform, beta'1, which is encoded by a specific mRNA. Neurite extension further increases tubulin heterogeneity and leads to the appearance of post-translationally modified isoforms: beta'2 in neuroblastoma and alpha 2 in teratocarcinoma cells. beta' 2 is shown to derive from the above mentioned beta'1 by phosphorylation, while alpha 2 is probably an acetylated form of the common alpha 1-tubulin. These results show that specific changes in tubulin heterogeneity are induced at different steps of neuronal differentiation and are controlled both at the transcriptional (or post-transcriptional) and post-translational levels.

Animals↗
PubMed1997

Calretinin-like immunoreactivity in mormyrid and gymnarchid electrosensory and electromotor systems.

Calretinin-like immunoreactivity was examined in the electrosensory and electromotor systems of the two families of mormyriform electric fish. Mormyrid fish showed the strongest immunoreactivity in the knollenorgan electroreceptor pathway; in the nucleus of the electrosensory lateral line lobe (ELL) and the big cells of the nucleus exterolateralis pars anterior. Mormyromast and ampullary zones of the ELL showed calretinin-like immunoreactivity in the ganglion, granule, and intermediate cell and fiber layers. Mormyromast zones additionally showed labeling of apical dendrites and commissural cells, but the ampullary zone did not. In the electromotor system, two nuclei in the corollary discharge pathway showed labeling: in the paratrigeminal command-associated nucleus and the juxtalobar nucleus. Gymnarchus niloticus (Gymnarchidae) showed strongest calretinin-like immunoreactivity in part of the phase-coding pathway; in S-type electroreceptor afferents. Zones of the ELL not receiving phase-coder input had weak labeling. The electromotor system showed labeling in the lateral relay nucleus and less strongly in the medullary relay nucleus, but none in the pacemaker. The concentration of calcium-binding proteins in mormyrid and gymnarchid time-coding electrosensory pathways is consistent with the hypothesis that they play a role in preserving temporal information across synapses. Cell types that encode temporal characteristics of stimuli in precise spike times have high levels of calcium-binding proteins, but cells that re-code temporal information into presence or magnitude of activity have low levels. Some cell types in the electromotor pathways and early in the time-coding electrosensory pathways do not follow this hypothesis, and therefore preserve temporal information using a mechanism independent of calcium-binding proteins. In particular, electromotor systems may use extensive electrotonic coupling within nuclei to ensure precise timing.

Afferent Pathways↗
PubMed2004

Pharmacology of acetylcholine-mediated cell signaling in the lateral line organ following efferent stimulation.

Cholinergic efferent fibers modify hair cell responses to mechanical stimulation. It is hypothesized that calcium entering the hair cell through a nicotinic receptor activates a small-conductance (SK), calcium-activated potassium channel to hyperpolarize the hair cell. The calcium signal may be amplified by calcium-induced calcium release from the synaptic cisternae. Pharmacological tests of these ideas in the intact cochlea have been technically difficult because of the complex and fragile structure of the mammalian inner ear. We turned to the Xenopus laevis lateral line organ, whose simplicity and accessibility make it a model for understanding hair cell organ function in a relatively intact system. Drugs were applied to the inner surface of the skin while monitoring the effects of efferent stimulation on afferent fiber discharge rate. Efferent effects were blocked by antagonists of SK channels including apamin (EC50 = 0.5 microM) and dequalinium (EC50 = 12 microM). The effect of apamin was not enhanced by co-administration of phenylmethylsulfonyl fluoride, a proteolysis inhibitor. Efferent effects were attenuated by ryanodine, an agent that can interfere with calcium-induced calcium release, although relatively high (mM) concentrations of ryanodine were required. Fluorescent cationic styryl dyes, 4-di-2-asp and fm 1-43, blocked efferent effects, although it was not possible to observe specific entry of the dye into the base of hair cells. These pharmacological findings in the Xenopus lateral line organ support the hypothesis that effects of efferent stimulation are mediated by calcium entry through the nicotinic receptor via activation of SK channels and suggest the generality of this mechanism in meditating cholinergic efferent effects.

Acetylcholine↗
PubMed2005

Auditory physiology and anatomy of octavolateral efferent neurons in a teleost fish.

Vertebrate hair cell systems receive innervation from efferent neurons in the brain. Here we report the responses of octavolateral efferent neurons that innervate the inner ear and lateral lines in a teleost fish, Dormitator latifrons, to directional linear accelerations, and compare them with the afferent responses from the saccule, the main auditory organ in the inner ear of this species. Efferent neurons responded to acoustic stimuli, but had significantly different response properties than saccular afferents. The efferents produced uniform, omnidirectional responses with no phase-locking. Evoked spike rates increased monotonically with stimulus intensity. Efferents were more broadly tuned and responsive to lower frequencies than saccular afferents, and efferent modulation of the otolithic organs and lateral lines is likely more pronounced at lower frequencies. The efferents had wide dynamic ranges, shallow rate-level function slopes, and low maximum discharge rates. These findings support the role of the efferent innervation of the otolithic organs as part of a general arousal system that modulates overall sensitivity of the peripheral octavolateral organs. In addition, efferent feedback may help unmask biologically relevant directional stimuli, such as those emitted by a predator, prey, or conspecific, by reducing sensitivity of the auditory system to omnidirectional ambient noise.

Acoustic Stimulation↗
PubMed1997

Morphological studies of the lungs in chronic hypobaric hypoxia.

The aim of the present study was to evaluate the effect of hypobaric hypoxia on the changes observed within lung parenchyma, particularly in the surfactant system-forming structures. The experiment used male Wistar rats, 180-220g b.w. The animals were kept in a hypobaric chamber for 3, 10 and 30 days. Pressure in the chamber (380mm Hg) corresponded to air rarefaction at an altitude of 5500m. Control animals were kept in the same room near the chamber at normal atmospheric pressure. The changes observed in the lungs were evaluated basing on ultrastructural analysis by transmission electron microscopy. The present results indicate phasic character of the changes occurring within lung parenchyma, including the surfactant system-forming structures. In the early phase (3 days), destructive-exudative changes predominated (delamelation of type II pneumocytes; oedematous changes, damage to the alveolar lining layer, accumulation of alveolar macrophages). In the later phases, repair-proliferative processes were predominant (increased number of type II pneumocytes, focal intensification of fibroplasia). The changes within the surfactant system-forming structures were accompanied by the accumulation of granulocytes and monocytes (hypobaric conditions for 3 and 10 days) and blood platelets (hypobaric conditions for 30 days) in the vascular bed of the lungs. The pathomechanism of the changes observed in the surfactant system was discussed with regard to the vascular changes. The possibility of formation of blood platelets within the vascular system of the lungs was considered.

Animals↗
PubMed1992

Automated, on-line quantification of left ventricular dimensions and function by echocardiography with backscatter imaging and lateral gain compensation.

To provide on-line quantification of left ventricular cavity dimensions and function by echocardiography 60 control subjects and 10 patients with cardiac dysfunction were studied. A novel, ultrasound imaging system was used which was developed to detect and track, in real time, ventricular endocardial blood boundaries based on quantitative assessment of acoustic properties of tissue. In addition, lateral gain compensation, a robust and novel image enhancement procedure, was used to provide instantaneous measurement and display of cavity areas and functional indexes on a beat-by-beat basis within regions of interest drawn around the blood pool cavity. In control subjects, short-axis end-diastolic area averaged 13.1 +/- 3.7 cm2 (SD), end-systolic area 5.9 +/- 2.7 cm2, and fractional area change 55.6 +/- 11.2%. Apical views yielded corresponding values of 23.8 +/- 4.5 cm2, 15.5 +/- 3.4 cm2 and 34.7 +/- 7.8%. Instantaneous peak rate of cavity area change approximated 50 cm2/s in systole and 60 cm2/s in diastole in each view. Serial measurements of area and functional index were reproducible over intervals of 2 to 3 weeks. Patients with dilated ventricles exhibited average apical view area values of 49.1 +/- 6.1 cm2 and 43.1 +/- 4.9 cm2 in diastole and systole with a fractional area change of 12.2 +/- 3.0%. Thus, results with on-line echocardiographic backscatter imaging-assisted automated edge detection are reproducible and capable of delineating cardiac dysfunction conveniently, promptly and serially at the bedside.

Adult↗
PubMed1998

Plasticity in an electrosensory system. III. Contrasting properties of spatially segregated dendritic inputs.

Efferent neurons of the first-order electrosensory processing center of the brain, the electrosensory lateral line lobe (ELL), receive electroreceptor afferent input as well as feedback inputs descending from higher centers. These ELL efferents, pyramidal cells, adaptively filter predictable patterns of sensory input while preserving sensitivity to novel stimuli. The filter mechanism involves integration of centrally generated predictive inputs with the afferent inputs being canceled. The predictive inputs, referred to as "negative image" inputs, terminate on pyramidal cell apical dendrites and generate responses that are opposite those resulting from the predictable afference, hence integration of these signals results in attenuation of pyramidal cell responses. The system also shows a robust form of plasticity; the pyramidal cells learn, with a time course of a few minutes, to cancel new patterns of repetitive inputs. This is accomplished by adjusting the strength of excitatory and inhibitory apical dendritic inputs according to an anti-Hebbian learning rule. This study focuses on the properties of two separate pathways that convey descending information to pyramidal cell apical dendrites. One pathway terminates proximally, nearer to the pyramidal cell body, whereas the other terminates distally. Recordings of ELL evoked potentials, extracellular pyramidal cell spike responses, and intracellularly recorded synaptic potentials show that the pyramidal cells respond oppositely to moderate-frequency (> approximately 8 Hz) single pulse stimulation or repeated (1/s) tetanic activation of these two pathways. Repetitive activation of the proximally terminating pathway results in highly facilitating responses due to potentiation of pyramidal cell excitatory postsynaptic potentials (EPSPs). These same stimuli applied to the distally terminating pathway result in a reduction of pyramidal cell responses due to depression of EPSPs and potentiation of inhibitatory postsynaptic potentials (IPSPs). Anti-Hebbian plasticity was demonstrated by pairing tetanic stimulation of either pathway with changes in the postsynaptic cell's membrane potential. After stabilization of the response potentiation due to tetanic stimulation of the proximally terminating pathway, paired postsynaptic hyperpolarization resulted in further increases in spike responses and additional potentiation of pyramidal cell EPSPs. Paired postsynaptic depolarization reduced subsequent responses to the tetanus, depressed EPSP amplitudes, and, in many cases, potentiated IPSPs. The same pattern of plasticity was observed when postsynaptic hyper- or depolarization was paired with tetanic stimulation of the distally terminating pathway except that the plasticity was superimposed on the depressed pyramidal cell responses resulting from stimulating this pathway alone. Modulation of a postsynaptic form of synaptic depression is proposed to account for the anti-Hebbian plasticity associated with both pathways.

Animals↗
PubMed2000

Nervous and sensory system correlates of an epibenthic evolutionary radiation in antarctic notothenioid fishes, genus Trematomus (Perciformes; Nototheniidae).

The perciform suborder Notothenioidei consists of 120 species, with 94 confined to the Antarctic Region of the Southern Ocean. On the Antarctic shelf, this phyletic radiation has been accompanied by a substantial morphological and ecological diversification towards a pelagic existence. For example, the primarily benthic genus Trematomus contains an epibenthic radiation that includes T. loennbergii, T. lepidorhinus, and T. eulepidotus. By comparing these epibenthic species with three congeneric benthic species (T. scotti, T. pennellii, and T. bernacchii) we tested three null hypotheses regarding brain variation in Antarctic trematomids: 1) that there is no difference in brain morphology among the six species; 2) that phylogenetic and ecological factors do not influence brain morphology; and 3) that peripheral sensory structures do not influence brain morphology. We rejected each of these hypotheses, leading us to conclude that Trematomus brains vary interspecifically, between benthic and epibenthic species, and with a species' depth distribution. Further, we conclude that brain variation is correlated with differences in peripheral sensory systems and motor activity. Specifically, epibenthic Trematomus have larger percentages of their brain volume devoted to lateral line mechanoreceptive and motor (cerebellar) structures. Species living at greater depths have low ratios of cones:rods in the retina and larger olfactory structures.

Animals↗
PubMed1987

A possible neurotransmitter role for CGRP in a hair-cell sensory organ.

We report that calcitonin gene-related peptide (CGRP) increases the discharge rate of afferent fibers innervating hair cells in the lateral line organ of Xenopus laevis. We have localized CGRP-like immunoreactivity in small, presumably efferent, fibers innervating the lateral line organ. In addition to providing evidence for a neurotransmitter role for CGRP in a sensory system, these results may help explain the non-cholinergic excitatory effect seen with efferent stimulation in this and other hair cell organs such as the inner ear.

Action Potentials↗