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At least 1,405 records · Page 78Linked to original sources

PubMed2000

David and Goliath - the slingshot that started the neuropeptide revolution.

This review in honor of David de Wied summarizes the work done in my laboratory that first indicated that adrenocorticotropic hormone (ACTH) has a direct effect on the neuromuscular system. Cold stress or ACTH and its related peptides alpha-melanocyte-stimulating hormone (alpha-MSH ) and beta-lipotropin improve the electromechanical characteristics of adrenalectomized and hypophysectomized rats. ACTH-(1-39) accelerates the return of motor and sensory function and improves the morphological characteristics of the motor endplate after peripheral nerve crush. The non-corticotropic fragments ACTH-(4-10), alpha-MSH, the ACTH-(4-9) analogue Organon 2766 (Org 2766) or the ACTH-(4-10) analogue Biomeasure 22015 (BIM 22015) improve electrophysiological and morphological parameters of the regenerating neuromuscular system. ACTH-(4-10) immunoreactivity, present in ventral horn motor neurons in low levels, is decreased ipsilaterally following ipsilateral nerve crush but increases both ipsilaterally and contralaterally if injured animals are treated with ACTH-(4-10) indicating a neuroprotective action. Similarly, Org 2766 appears to have a protective action in the brain following nigrostriatal lesions. In developmental studies, perinatal exposure to ACTH peptides improves the structure of the neuromuscular junction, accelerates the maturation of electromechanical properties and enhances nerve-muscle integration and nerve regeneration. Perinatal exposure to these peptides decreases adult male sexual behavior, a change correlated with increased serotinergic input within the medial preoptic area. Similar changes occur in female rats and appear to be long-lasting. In tissue culture studies, both Org 2766 and BIM 22015 promote neurite outgrowth in the absence of nerve growth factor, indicating a neurotrophic role for these peptides.

Adrenocorticotropic Hormone↗

PubMed2003

The potent melanocortin receptor agonist melanotan-II promotes peripheral nerve regeneration and has neuroprotective properties in the rat.

The neurotrophic and neuroprotective potential of the alpha-melanocyte-stimulating hormone (alpha-MSH) analog cyclo-[Ac-Nle(4),Asp(5),D-Phe(7),Lys(10)]alpha-MSH-(4-10) amide (melanotan-II), a potent melanocortin receptor agonist, was investigated. The sciatic nerve crush model was used as a paradigm to investigate the neurotrophic properties of melanotan-II. Melanotan-II significantly enhanced the recovery of sensory function following a crush lesion of the sciatic nerve in the rat at a dose of 20 microg kg(-1) per 48 h, s.c., but not at a dose of 2 or 50 microg kg(-1). In addition, we observed that melanotan-II also possesses neuroprotective properties, as it partially protected the nerve from a toxic neuropathy induced by cisplatin. Thus, the present data for the first time demonstrate the effectiveness of the potent alpha-MSH analog melanotan-II in nerve regeneration and neuroprotection.

Animals↗

PubMed2002

The effects of thyroxine or a GnRH analogue on thyroid hormone deiodination in the olfactory epithelium and retina of rainbow trout, Oncorhynchus mykiss, and sockeye salmon, Oncorhynchus nerka.

Using low (0.5nM) substrate levels we determined the activities of thyroxine (T4) outer-ring deiodination (ORD), T4 inner-ring deiodination (T4IRD) and 3,5,3(')-triiodothyronine (T3) IRD activities in the olfactory epithelium (OLF) and retina (RET) of laboratory-held immature 1-year-old rainbow trout and immature 2.5-year-old sockeye salmon. In both species all three deiodination activities were detected in OLF and RET. For OLF, no particular pathway predominated and activities were similar to those of brain. For RET, T3IRD activity was greater than T4ORD activity and in sockeye RET T3IRD activity exceeded that of liver. Trout immersion for 6 weeks in 100ppm T4 increased plasma T4 levels 3-fold and plasma T3 levels by 50% and caused the anticipated autoregulatory responses in brain and liver deiodination ( downward arrow T4ORD, upward arrow T4IRD, and upward arrow T3IRD); OLF deiodination and RET T4ORD activity were unaltered but RET T4IRD and T3IRD activities increased dramatically. Two injections of a GnRH analogue (20 microgkg(-1)) into sockeye increased plasma T3 levels but not T4 levels and decreased RET T4IRD and T3IRD activities without changing liver, brain, or OLF deiodination. We conclude that in salmonids the main TH deiodination pathways occur in OLF but show no regulation by T4 or GnRH. In contrast, T3IRD activity predominates in RET and can be regulated by T4 and GnRH, suggesting that for RET plasma may be the major T3 source. These findings have implications for thyroidal regulation of sensory functions during salmonid diadromous migrations.

Animals↗

PubMed1998

Replantation of multi-level hand severances.

Since 1990, the replantation of hands severed at multiple levels has been carried out successfully for 22 patients. In each case the motor and sensory functions of the hand were recovered satisfactorily. We suggest that such wounds should be named 'multi-level severances' and should be classified into five groups according to the wound localities. In order to shorten ischaemic time, debridement should be carried out simultaneously by several groups. The main technical points of the operation are: (1) The order of replantation for multiply severed fingers is that the most distant section should be reattached first, and then the more proximal part. (2) High quality blood vessel anastomosis must be ensured. (3) Avoid taking the blood vessels, nerves and tendons from severed region. (4) During the operation, care should be taken to ensure that the replanted fingers' segments are protected from collision and stretching. In the early stages following the operation correct functional exercise is very important.

Accidents, Occupational↗

PubMed1998

Stomach distension increases efferent muscle sympathetic nerve activity and blood pressure in healthy humans.

Although the enteric nervous system is usually described as a separate and independent entity, animal studies show that gastric distension causes a reflex increase in arterial pressure and a sympathetically mediated increase in heart rate and peripheral vascular resistance. To assess the influence of gastric distension on sympathetic outflow and blood pressure, we recorded muscle sympathetic nerve activity (MSNA) from the peroneal nerve by microneurography in eight healthy volunteers. The stomach was distended by means of a barostat, using a single staircase protocol by which pressure was increased by 2 mmHg every 3 min. Gastric sensory function was assessed at each distension step by using a visual analog scale (VAS) for sensations of fullness, nausea and pain. For comparison, we also performed a cold pressor test. The MSNA increased on barostat-induced gastric distension with an almost concomitant elevation of blood pressure. The increase in both was proportional to the intragastric pressure and both decreased towards initial values after the end of distension. Heart rate increased inconsistently and only at higher distension pressures that were associated with high VAS scores. The opposite was found for the cold pressor test. The results of this study confirm the existence of a functional relationship between gastrointestinal distension and cardiovascular function. Decrease in this gastrovascular response may play a role in postprandial hypotension in the elderly, since the MSNA responses to simulated microgravity decrease with age.

Adult↗

PubMed2003

Electrophysiological assessment of sensations arising from the bladder: are there objective criteria for subjective perceptions?

PURPOSE: Initial bladder filling sensation, first and strong desire to void are subjective perceptions that occur periodically during the urine storage mode of bladder function, representing sensory input from the lower urinary tract. To our knowledge methods for evaluating sensory bladder function are not available. We studied a simple electrophysiological procedure for the objective assessment of bladder sensations using sympathetic skin responses and surface pelvic floor electromyography. MATERIALS AND METHODS: Informed consent was provided by 8 healthy male subjects, who were administered 20 mg. furosemide and 1 l. fluid to drink. Palmar and plantar sympathetic skin responses, and surface pelvic floor electromyogram were continuously recorded during bladder filling, voluntary pelvic floor contraction and voiding. RESULTS: First desire to void evoked simultaneous sympathetic skin responses and pelvic floor contractions. This pattern appeared periodically with the desire to void sensation as well as with strong desire to void at maximum bladder capacity and it correlated well with the subjective sensation of the subjects. Voluntary pelvic floor contraction decreased the subjective intensity of the desire to void sensation as well as sympathetic skin response activity for the same short period. During voiding sympathetic skin responses almost complete absence of sympathetic skin responses was observed. CONCLUSIONS: Sensations arising from the bladder induce combined activation of sympathetic skin responses and pelvic floor activity. This coherence indicates synchronized activation and inactivation of the autonomic and somatic pathways necessary for appropriate urine storage and coordinated voiding. Our observations may introduce a new approach for objectively assessing subjective sensations arising from the urinary tract.

Adult↗

PubMed2002

17Beta-estradiol inhibits high-voltage-activated calcium channel currents in rat sensory neurons via a non-genomic mechanism.

There is increasing evidence that estrogen influences electrical activity of neurons via stimulation of membrane receptors. Although the presence of intracellular estrogen receptors and their responsiveness in dorsal root ganglion (DRG) primary sensory neurons were reported, rapid electrical responses of estrogen in DRG neurons have not been reported yet. Therefore the current study was initiated to examine the rapid effects of estrogen on Ca2+ channels and to determine its detailed mechanism in female rat DRG neurons using whole-cell patch-clamp recordings. Application of 17beta-estradiol (1 microM) caused a rapid inhibition on high-voltage-activated (HVA)-, but not on low-voltage-activated (LVA)-Ca2+ currents. This rapid estrogen-mediated inhibition was reproducible and dose-dependent. This effect was also sex- and stereo-specific; it was greater in cells isolated from intact female rats and was more effective than that of 17alpha-estradiol, the stereoisomer of the endogenous 17alpha-estradiol. In addition, ovariectomy reduced the inhibition significantly but this effect was restored by administration of estrogen in ovariectomized subjects. Occlusion experiments using selective blockers revealed 17beta-estradiol mainly targeted on both L- and N-type Ca2+ currents. Overnight treatment of cells with pertussis toxin profoundly reduced 17beta-estradiol-mediated inhibition of the currents. On the other hand, estradiol conjugated to bovine serum albumin (EST-BSA) produced a similar extent of inhibition as 17beta-estradiol did. These results suggest that 17beta-estradiol can modulate L- and N-type HVA Ca2+ channels in rat DRG neurons via activation of pertussis toxin-sensitive G-protein(s) and non-genomic pathways. It is likely that such effects are important in estrogen-mediated modulation of sensory functions at peripheral level.

Animals↗

PubMed2003

Impaired 0.1-Hz vasomotion assessed by laser Doppler anemometry as an early index of peripheral sympathetic neuropathy in diabetes.

Impairment of 0.1-Hz vasomotion, which was found in diabetic patients, was suggested to be an early index of sympathetic dysfunction. We studied the relationships between alterations in vasomotion and both cardiac autonomic and sensory neuropathy. Twenty type 1 and 22 type 2 diabetic patients were investigated. Vasomotion was recorded in single capillaries at the dorsal middle phalangeal area of the left ring finger by means of laser Doppler anemometry. Cardiac autonomic neuropathy was assessed by spectral analysis of heart rate variation during rest and recording heart rate responses to deep breathing and Valsalva manoeuvre. Sensory neuropathy was investigated by measuring heat pain, vibration, and thermal sensory thresholds. Impaired vasomotion was more often (82.4%) found in diabetic patients with at least one altered cardiac autonomic test, but also in 47.1% of those with all of these tests being normal (P = 0.035). Both heart rate variation coefficient during rest (r = 0.40, P = 0.045) and Valsalva ratio (r = 0.41, P = 0.037) correlated positively with amplitudes of vasomotion in type 1 diabetic patients. The prevalence of impaired vasomotion was not higher in patients with sensory neuropathy compared to those with normal sensory functions. A disturbed warm sensation was only found in 2 patients and none had an abnormal heat pain threshold. Our data indicate that impairment of 0.1-Hz vasomotion precedes parasympathetic neuropathy, assessed by heart rate variation tests, and abnormalities in warm and heat pain sensation. Reduction of arteriolar vasomotion, detected by laser Doppler anemometry, might be an early index of sympathetic dysfunction, because it correlates with disturbances in those cardiac autonomic tests, which are at least in part under sympathetic control.

Adult↗

PubMed2005

[Transplantation of olfactory ensheathing cells after spinal injury. II--Experimental variability and clinical perspectives].

Over recent years, a certain number of experimental investigations have studied the effect of the transplantation of olfactory ensheathing glial cells (OEC) after spinal traumatism in animal, the rat in particular. Some of these studies have reported improvements in motor (mainly locomotor, postural and respiratory) and sensory function. While these new data provide additional support for the interest of the strategy of EOC transplantation to minimise the incapacitating effects of spinal pathologies in clinical therapy, it nonetheless remains necessary to continue experiments on animal models in order to better understand and master certain important points: beneficial effects according to the nature and composition of the transplants; therapeutic impact according to the type of pathology and the nature of the traumatism; influence of the dose effect; migration of the transplanted OECs (distance, pathways); active principles of the transplants; beneficial effect on various functions, in particular at the level of the vesico-sphincteric area; long-term innocuousness; long-term posttraumatic efficacy. Although therapeutic trials are in progress in certain countries (Australia, China, Portugal), it would nonetheless appear essential that these somewhat obscure points should be better understood before any clinical application might be seriously envisaged, in order to respect the principles of precaution, maximum efficacy and observance of the prevailing ethical rules.

Animals↗

PubMed2002

Attentional demands of continuously monitoring orientation using vestibular information.

The aim of this series of experiments was to determine whether attention is normally required for continuously processing vestibular information concerning orientation, or is required only when orientation is disrupted (eg by vestibular dysfunction or by conflicting visual and vestibular orientation cues). In the first two studies, healthy subjects were passively oscillated, and indicated when they perceived they were passing through their starting position. There was only weak evidence for interference between performance on this 'continuous orientation monitoring task' and on concurrent mental tasks. However, a third study showed that when patients with vestibular imbalance carried out the continuous orientation monitoring task their performance on a concurrent mental arithmetic task was substantially impaired. This dual task interference was correlated with inaccuracy in judging orientation on the continuous orientation monitoring task, which in turn correlated with severity of recent vestibular symptomatology (assessed by questionnaire). In a fourth experiment, disorientation was induced in healthy subjects by rotating the visual field about the line of sight. Bidirectional interference was observed between monitoring orientation (assessed by accuracy in setting a rod to the perceived vertical) and performance of an arithmetic task. Dual task interference was correlated with baseline levels of disorientation induced by the visual field, as indicated by inaccuracy in judging the visual vertical. These findings suggest that monitoring orientation makes significant demands upon cortical processing resources when disorientation is induced, whether the disorientation results from deficient sensory functioning or from ambiguous perceptual information.

Adult↗

PubMed1999

An event-related brain potential study of receptive speech comprehension using a modified Token Test.

There is a long and distinguished history of evaluating sensory functions with evoked potentials (EPs). However, the clinical utility of event-related brain potentials (ERPs) in the assessment of cognitive functions remains to be established. We present evidence for the efficacy of ERPs in the assessment of speech comprehension. In this normative study, a version of the Token Test (Boller and Vignolo, 1966, Brain, 89, 815-831: De Renzi and Vignolo, 1962, Brain, 85, 665-678) was modified for computer presentation with simultaneous ERP recordings and then administered to a group of healthy individuals (n = 27). A differential neural response pattern to incorrect and correct test items was obtained for the group and, more importantly, this result was also observed reliably at the individual subject level. This research complements on-going efforts in our laboratory to develop innovative measures for patients that are difficult or impossible to assess due to motoric and/or communicative limitations.

Adolescent↗

PubMed2001

Forehead and temple reconstruction.

Reconstruction of the forehead and temple region poses special aesthetic challenges for maintaining eyebrow symmetry and hairline. The preservation of motor and sensory function is also important. There are a wide variety of techniques available to the reconstructive surgeon, and these methods are compared and discussed with specific reference to the forehead and temple region.

Forehead↗

PubMed1997

Reduction in buoyancy alters parameters of motility in E9 chick embryos.

Over the course of embryonic development, chick embryos express 3 different types of motility (I, II, III). Although neural pattern generators appear to control embryonic motility, the mechanisms responsible for the sequential emergence and/or transformations in these behaviors are not known. Given the early presence of functional sensory connections and substantial changes in movement dynamics associated with body growth in the fixed volume of an egg, it was hypothesized that changes in environmental constraints might contribute to shaping the transformations in motility. In this study, we tested the hypothesis that changes in buoyancy can alter parameters of motility in ovo at embryonic Day 9 (E9). Results demonstrate that attributes of Type I motility can be altered by a reduction in buoyancy. The possible contributions of the environment and experience to transformations in embryonic motor behavior are discussed.

Animals↗

PubMed1999

Anion size of sodium salts and simple taste reaction times.

Simple taste reaction times (RT) and taste intensities were measured in adult humans for 100-mM aqueous solutions of sodium chloride, acetate, glutamate, ascorbate, and gluconate flowed over the anterodorsal tongue with a closed liquid delivery system. Results from 12 subjects showed a significant increase in RT with molecular weight of the tastant, and a correlation of 0.941 between RT and the square roots of anionic weights. A multiple regression analysis controlling for perceived taste intensity indicated that RT increased linearly with the square root of the anionic weight. These findings support a model that includes both the permeability of ions through the tight junctions between the taste receptor cells of fungiform papillae taste buds and the effects of ions at apical portions of the receptor cells. They also suggest that gustatory transduction of sodium salts in humans normally involves intercellular spaces of taste buds as part of the functional sensory structures, in addition to individual taste receptor cells.

Adolescent↗

PubMed1999

Salt sensitivity and hydration behavior of the toad, Bufo marinus.

Toads, Bufo marinus, were placed on laboratory tissue saturated with water or with hyperosmotic (250 or 500 mM NaCl or KCl) solutions, and their behavior was observed for 5 min. Toads placed on water initially allowed their ventral skin to touch the surface without abducting the hind limbs. During this "seat patch down" (SPD) behavior toads appeared to be evaluating the suitability of a hydration source prior to initiating "water absorption response" (WR) behavior with the hind limbs fully abducted and the ventral skin pressed to the moist surface. Toads dehydrated by more than 10% showed significantly shorter periods of SPD behavior and initiated WR behavior more frequently than did hydrated toads. Dehydrated toads placed on 250 mM NaCl initiated WR behavior in only 18% of the trials, but spent significantly more time showing SPD behavior than they did on water, indicating that this concentration is marginally acceptable to them. Recordings from spinal nerve #6 showed an increase in activity when 250 mM NaCl or KCl solutions were perfused over the outer surface of the ventral skin. The response to KCl was significantly greater than NaCl. The addition of 10 microM amiloride to 250 mM NaCl resulted in a higher frequency of WR behavior and reversibly inhibited the neural response to 250 mM NaCl. These results suggest that epithelial Na+ channels in the skin serve a sensory function in this species. Neither the hydrated nor dehydrated toads initiated WR behavior on 250 or 500 mM KCl solutions, indicating that toads have a lower tolerance of K+ than of Na+ salts.

Amiloride↗

PubMed2004

[Devic's optic neuromyelitis and viral hepatitis type A. A paediatric case report].

INTRODUCTION: Devic optic neuromyelitis is a rare clinical disease that involves severe transverse myelitis and unilateral or bilateral optic neuropathy. Its pathogenesis would be explained by demyelinization triggered by bacterial or viral infections phenomena. According to several author, prognosis would be better in children. CASE REPORT: We report a case of optic neuromyelitis in an 8-year-old child with an uneventful history who was admitted because he suffered from flaccid tetraplegia and sudden decline of the visual acuity. The ophthalmologic examination revealed bilateral neuropapillitis. The medullary MRI visualized a spreading myelitis with bifocal arachnoiditis. Search for a precipitating infectious factor showed positive IgM for viral hepatitis A. With corticosteroid treatment the child achieved total recovery of vision and recovered motor and sensorial function of the upper limbs and the trunk. Paraplegia with sphincteral disorders persisted. CONCLUSION: This case characterized by the precipitating factor (hepatitis virus A), illustrates this rare syndrome. We present a general review of the pediatric cases reported in the literature.

Child↗

PubMed1980

Funicular orientation by electrical stimulation and internal neurolysis in peripheral nerve suture.

Eleven peripheral nerve lacerations around the wrists of ten patients were treated with funicular suture or nerve graft. In three freshly lacerated nerves funicular orientation could be made only by electrical stimulation to both cut ends. The electrophysiological method was also utilised to obtain funicular orientation of a proximal stump in eight old nerve lacerations. However, funicular orientation of the distal stump of old lacerations, which was not responsive to electrical stimulation, was performed anatomically by internal neurolysis from a terminal branching area up to a distal stump. By six months after the operation, motor and sensory functions of the patients with funicular suture had recovered to an excellent degree with rapid reinnervation.

Adolescent↗

PubMed2006

Role of the urothelium in urinary bladder dysfunction following spinal cord injury.

A consequence of spinal cord injury is a change in bladder reflex pathways resulting in the emergence of detrusor hyperreflexia and increased activity of the urethral sphincter. A basis for some of these alterations could be changes in the environment of bladder sensory nerve endings at the target organ. Recent evidence suggests that the urothelium (the lining of the urinary bladder) plays a prominent role in modulating bladder sensory nerve ending excitability. It is conceivable that factors and processes affecting the plasticity of bladder neurons after spinal cord injury may be partly due to changes occurring in the urothelium. Although the urothelium has classically been thought of as a passive barrier to ions/solutes, a number of novel properties have been recently attributed to these cells. Our work and that of others clearly demonstrates that the urothelium exhibits both "sensor" (expression of sensor molecules or response to thermal, mechanical and chemical stimuli) as well as "transducer" (release of factors/transmitters) properties. Taken together, these and other findings discussed in this chapter suggest a sensory function for the urothelium and that alterations in urothelial properties may contribute to afferent abnormalities following spinal cord injury.

Botulinum Toxins↗