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Biomedical subjects

C D Balaban

Publications and source records attributed to C D Balaban.

At least 55 records · Page 3Linked to original sources
PubMed1997

Adaptation to capsaicin within and across days.

Subjects judged the time-course of the burn caused by 100 ppm capsaicin applied to the tongue on Day 1 and Day 5. On Days 2-4, they tasted hard candy containing capsaicin. Most subjects did not show adaptation within Day 1, but either plateaued after about 16 min or rose monotonically for the entire 34 min. Intensity was less on Day 5 and levelled off or declined for most subjects. Data were fit to a mathematical model of adaptation. Adaptation across days was accounted for by changes in the gains of the three processes.

Adaptation, Physiological↗
PubMed1997

Immunohistochemistry of lymphocytes and macrophages in human celloidin-embedded temporal bone sections with acute otitis media.

Immunohistochemical analyses were used to investigate the distribution of lymphocytes and macrophages in routine human temporal bone sections obtained from a subject with acute suppurative otitis media. Primary antibodies specific for human CD3 and CD43 (T-lymphocytes), CD20 (B-lymphocytes), CD45 (leukocyte common antigen), and CD68 (macrophages) were used. As a pretreatment, the sections were soaked in antigen retrieval solution (saturated sodium hydroxide-methanol solution in methanol at a ratio of 1:3). A second antigen retrieval procedure (microwave treatment in 1% zinc sulfate) was also employed for identifying CD3-positive cells. Then the avidin-biotin-peroxidase complex technique was performed. Positive reactions to all antibodies but anti-CD68 were observed in the mucosa of the eustachian tube, tympanic cavity, and mastoid air cells. Particularly, cells positive to anti-CD3 or anti-CD43 were making a diffuse invasion upon the lamina propria. CD68-positive cells were scattered only in the effusion of mastoid air cells. These results suggest that the retrospective immunohistochemical study of archival temporal bone sections is a promising approach to investigate the pathogenesis of otitis media.

Acute Disease↗
PubMed1997

Vestibular compensation in a patient with a cerebellar infarction.

We report the case of a 67-year-old man who suffered a traumatic unilateral peripheral vestibular injury subsequent to an unrelated prior cerebellar infarction that occurred at least 2 years earlier. The patient's clinical course was marked by poor compensation for his peripheral vestibular loss. Four months after his vestibular injury, his symptoms of dizziness had not resolved. He had a spontaneous vestibular nystagmus, and laboratory testing indicated an asymmetric semicircular canal-ocular reflex. The otolith-ocular reflex, tested using off-vertical axis rotation, also was asymmetric but had a preserved modulation component. Visual-vestibular interaction and semicircular canal-otolith interaction were normal. An MRI indicated preservation of the flocculo-nodular lobe but infarction of the pyramis and uvula. Taken together, the findings in this case suggest that despite structural and functional preservation of the flocculo-nodular lobe, an anatomic region often labeled the "vestibulo-cerebellum", a lesion of the cerebellum that can impair CNS compensation for a unilateral peripheral lesion in humans.

Adaptation, Physiological↗
PubMed1996

Interaction between head-down tilt and anterior chamber infusions on intraocular pressure of anesthetized rats.

Head-down tilt or infusions of a balanced salt solution into the anterior chamber of the eye raise intraocular pressure. We measured intraocular pressure directly in adult male Sprague-Dawley rats, anesthetized with pentobarbital, and subjected to 45 degrees head-down tilt alone, tilt with an anterior chamber infusion (0.087 microliter min-1), or tilt with an infusion containing arginine vasopressin. The intraocular pressure of the three groups differed during the 1 hr tilt and recovery periods. In the case of tilt alone, intraocular pressure quickly reached a peak after tilting, partially decreased during the tilt period, recovered to baseline immediately after tilt, then a secondary rise occurred. Combined infusion and tilt caused a slower rise to peak intraocular pressure, and only a partial recovery occurred during the 1 hr recovery period. Combined vasopressin infusion and tilt caused a gradual rise in intraocular pressure of a lesser magnitude than the other groups, followed by a rapid recovery to baseline pressure and no secondary rise. Systemic arterial pressure was stable within and between the groups. The underlying mechanism for these differing response patterns is unknown. However, some evidence indicates that infusions are independent of aqueous synthesis rate, and that vasopressin, acting on a V1 receptor subtype reached from the anterior chamber, exerts a vascular effect.

Analysis of Variance↗
PubMed1996

Vestibular nucleus projections to the parabrachial nucleus in rabbits: implications for vestibular influences on the autonomic nervous system.

Acute vestibular dysfunction and motion sickness are characterized by autonomic effects such as pallor, nausea, and vomiting. Previous anatomic and physiologic studies suggest that one potential mediator of these effects may be light, direct vestibular nuclear projections to the nucleus tractus solitarius and the dorsal motor nucleus of the vagus nerve. This study presents evidence for relatively dense, direct projections from the vestibular nuclei to the parabrachial nucleus. Male albino rabbits received injections of Phaseolus vulgaris leucoagglutinin into the vestibular nuclei. The tracer was visualized immunocytochemically with standard techniques. Anterogradely labeled axons were traced bilaterally from the vestibular nuclei to the parabrachial nuclear complex, where they terminated around somata in the Kölliker-Fuse nucleus, external medial parabrachial nucleus, medial parabrachial nucleus, and lateral parabrachial nucleus. Less dense terminations were observed in the ventrolateral aspect of the medullary reticular formation, the subtrigeminal nucleus, lateral tegmental field, and nucleus ambiguus. These findings have several important implications. First, they suggest that vestibular input converges directly at brain stem levels with visceral sensory input in both nucleus of the solitary tract and the parabrachial complex. Second, they suggest that vestibular input influences brain stem autonomic outflow via two parallel pathways: (1) direct, light projections to the nucleus of the solitary tract, dorsal motor nucleus of the vagus nerve, and ventrolateral medullary reticular formation; and (2) denser projection to regions of the parabrachial nucleus that project to these brain stem regions. Finally, since the parabrachial nucleus regions that receive vestibular input also project to the hypothalamus and the insular and infralimbic prefrontal cortex, the parabrachial nucleus may serve as an important relay and integrative structure for the cognitive impairment and vegetative symptoms associated with motion sickness, vestibular dysfunction, and responses to altered gravitational environments.

Afferent Pathways↗
PubMed1996

Comparison of anterior chamber infusates on the intraocular pressure of intact rat eyes.

1. Infusions of balanced salt solutions (BSS) into the eye often cause a delayed, gradual increase in intraocular pressure or outflow facility, known as the "washout" effect. The reason(s) is occult, especially at low input rates when drainage mechanisms are not overloaded by excessive volume input. However, direct, quantitative comparisons of BSSs used in ocular research have been reported infrequently. 2. We compared the effects of three BSSs on intraocular pressure and the estimated resistance to drainage after a 1-hr, low-volume infusion into the anterior chambers of the eyes of anesthetized rats. 3. The BSSs tested raised intraocular pressure (P < 0.05) after a 20-40-min delay, and the highest IOPs occurred at 1 hr. Recovery of intraocular pressure to baseline only occurred with one BSS (Dulbecco). 4. Fitting the ascending and descending portions of the mean pressure curves to an exponential revealed differences among the infusates. The Dulbecco solution resulted in minimal changes in time constant, gain, and offset during the ascending and descending periods. 5. The data obtained show that different BSSs yield pressure curves that appear grossly similar, even though there were large differences in composition and osmolality. However, the underlying changes in ocular dynamics were not identical. Thus, it may be prudent to test more than one solvent to study "washout," or to deliver drugs directly into the anterior chamber.

Animals↗
PubMed1996

Anatomy and physiology of the primate interstitial nucleus of Cajal I. efferent projections.

1. The efferent projections of the interstitial nucleus of Cajal (NIC) were studied in the squirrel monkey after iontophoretic injections of biocytin and Phaseolus Vulgaris leucoagglutinin into the NIC. To ensure the proper placement of the tracer, the same pipettes were used to extracellularly record the discharge pattern of NIC neurons. 2. Three projection systems of the NIC were distinguished: commissural (through the posterior commissure), descending, and ascending. 3. The posterior commissure system gave rise to dense terminal fields in the contralateral NIC, the oculomotor nucleus, and the trochlear nucleus. 4. The descending system of NIC projections deployed dense terminal fields in the ipsilateral gigantocellular reticular formation and the paramedian reticular formation of the pons, as well as in the ventromedial and commissural nuclei of the first two spinal cervical segments. It also gave rise to moderate or weak terminal fields in the vestibular complex, the nucleus prepositus hypoglossi, the inferior olive, and the magnocellular reticular formation, as well as cell groups scattered along the paramedian tracts in the pons and the pontine and medullary raphe. 5. The ascending system of NIC projections gave rise to dense terminal fields in the ipsilateral mesencephalic reticular formation and the zona incerta as well as moderate or weak terminal fields in the ipsilateral centromedian and parafascicular thalamic nuclei. It also provided dense bilateral labeling of the rostral interstitial nucleus of the medial longitudinal fasciculus and the fields of Forel, and moderate or weak bilateral labeling of the mediodorsal, central medial, and central lateral nuclei of the thalamus. 6. Models of saccade generation that rely on feedback from the velocity-to-position integrators and include the superior colliculus in their local feedback loop are contradicted because no fibers originating from the NIC traveled to the superior colliculus to deploy terminal fields. 7. Consistent with its morphological and functional diversity, these data indicate that the primate NIC sends signals to a multitude of targets implicated in the control of eye and head movements.

Afferent Pathways↗
PubMed1995

Vestibular inputs to the lateral tegmental field of the cat: potential role in autonomic control.

The lateral tegmental field (LTF), which is comprised of the lateral reticular formation near the obex, is an important integrative area involved in cardiovascular control and the production of emesis. Using neuroanatomical and electrophysiological techniques, we tested the hypothesis that LTF neurons receive vestibular inputs; the neurons studied included those projecting into the subretrofacial rostral ventrolateral medulla (sRVLM), which contains cells that make direct connections with sympathetic preganglionic neurons. Injections of the anterograde tracer PHA-L into the medial and inferior vestibular nuclei produced labeled terminals in the LTF. Electrical stimulation of the vestibular nerve affected the firing rate of LTF neurons, including approximately one-third of those antidromically activated from the sRVLM. The response latencies ranged from 1.5 to 20 ms, suggesting that the neurons received both direct and polysynaptic vestibular inputs from the vestibular nuclei. The LTF may be involved in the production of vestibulosympathetic reflexes and vestibular-elicited vomiting.

Animals↗
PubMed1995

Effects of angiotensin, vasopressin and atrial natriuretic peptide on intraocular pressure in anesthetized rats.

The effects of atrial natriuretic peptide (ANP), vasopressin (AVP) and angiotensin (ANG) on blood and intraocular pressures of pentobarbital anesthetized rats were evaluated following intravenous, intracerebroventricular or anterior chamber routes of administration. Central injections did not affect intraocular pressure. Equipressor intravenous infusions of ANG raised, whereas AVP decreased, intraocular pressure. Direct infusions of a balanced salt solution (0.175 microliter/min) raised intraocular pressure between 30 and 60 min. Adding ANG or ANP slightly reduced this solvent effect but AVP was markedly inhibitory. An AVP-V1 receptor antagonist reversed the blunting of the solvent-induced rise by the peptide, indicating receptor specificity. Acetazolamide pretreatment lowered intraocular pressure, but the solvent-induced rise in intraocular pressure and inhibition by AVP still occurred without altering the temporal pattern. Thus, these effects appear unrelated to aqueous humor synthesis rate. The data support the possibility of intraocular pressure regulation by peptides acting from the blood and aqueous humor.

Acetazolamide↗
PubMed1995

N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) has differential efficacy for causing central noradrenergic lesions in two different rat strains: comparison between Long-Evans and Sprague-Dawley rats.

We tested the hypothesis that Long-Evans (LE) and Sprague-Dawley (SD) rat strains were equally sensitive to the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) with respect to central lesions of locus coeruleus (LC) terminals as measured by immunohistochemical localization of dopamine-beta-hydroxylase (D beta H). Analysis of D beta H immunoreactivity was made by both qualitative and quantitative methods. Intraperitoneal injections of 50 mg/kg DSP-4 caused a dramatic reduction of noradrenergic terminals in the neocortex, hippocampus and cerebellum of SD, but not LE rats as compared to saline-injected controls. This finding indicates that LE rats are less sensitive than SD rats to the neurotoxic effects of DSP-4 in the central nervous system.

Analysis of Variance↗
PubMed1994

Evidence for a noradrenergic projection to the subcommissural organ.

Several physiological studies have shown that the subcommissural organ (SCO) is influenced by catecholamines. This study provides immunohistochemical evidence for a noradrenergic input to the SCO of rats. A light plexus of tyrosine hydroxylase (TH)-and dopamine-beta-hydroxylase (D beta H)-positive axons present in the SCO of both Long-Evans and Sprague-Dawley rats. The innervation density was greatest in the hypendymal wing of the rostral aspect of the SCO and it declined both caudally in the hypendymal wing and medially in the hypendymal layer. Some TH- and D beta D beta H-immunoreactive fibers entered the lateral margin of the ependymal layer along the basal surface of ependymal cells; others coursed medially in the transverse plane to ramify along the base of the ependymal cells. These fibers are presumed to be noradrenergic because phenylethanolamine N-methyltransferase immunoreactivity was absent in adjacent sections through the SCO. Considering the potential role of the SCO region in sodium homeostasis, these data suggest that central noradrenergic input to the SCO may parallel peripheral catecholaminergic mechanisms that regulate sodium balance.

Adrenergic Fibers↗
PubMed1994

NMDA-mediated metabolic activation of the cerebellar cortex in behaving rats by the neuropeptide endothelin-1.

Generalized barrel-rolling convulsions and focal hypermetabolic responses in the cerebellar cortex of conscious rats to lateral ventricular injection of the neuropeptide, endothelin-1 (ET; 9 pmol), were diminished or eliminated by i.c.v. pretreatment with the glutamatergic NMDA receptor antagonist, MK-801 (44 nmol). Using the quantitative autoradiographic [14C]deoxyglucose technique, we assessed rates of glucose metabolism in individual structures anatomically connecting forebrain nuclei within a polysynaptic network linked to the cerebellar cortex. Cerebellar cortical afferent sources from specific subnuclei of the inferior olivary complex, cuneate nucleus, and medial vestibular nucleus, all of which were hypermetabolic following injection of ET alone, were also inhibited by MK-801. The findings indicate that a convulsive i.c.v. dose of ET elicits an NMDA-related stimulatory effect, whose origin is probably at the periventricular caudate nucleus, that activates rates of glucose metabolism in several afferent sources and subregions of the cerebellar cortex involved in the regulation of equilibrium, posture, and the visuovestibular system.

Animals↗
PubMed1994

Vestibular nucleus projections to nucleus tractus solitarius and the dorsal motor nucleus of the vagus nerve: potential substrates for vestibulo-autonomic interactions.

Autonomic effects of vestibular stimulation are important components of phenomena as diverse as acute vestibular dysfunction and motion sickness. However, the organization of neural circuits mediating these responses is poorly understood. This study presents evidence for direct vestibular nucleus projections to brain stem regions that mediate autonomic function. One group of albino rabbits received injections of Phaseolus vulgaris leucoagglutinin into the vestibular nuclei. The tracer was visualized immunocytochemically with standard techniques. Anterogradely labeled axons from the caudal medial vestibular nucleus (cMVN) and inferior vestibular nucleus (IVN) could be traced bilaterally to nucleus tractus solitarius (NTS). Fewer axons ended near the somata of neurons in the dorsal motor nucleus of the vagus nerve (DMX). A second group of rabbits received pressure or iontophoretic injections of cholera toxin B-HRP or Fluoro-Gold into a region including NTS and DMX. Retrogradely labeled neurons were observed bilaterally in the caudal half of cMVN and ipsilaterally in IVN. The labeled somata were small and they tended to occupy the center of cMVN in transverse sections. These previously unreported vestibular nucleus projections to NTS and DMX are a potential substrate for vestibular influences on autonomic function. In particular, they may contribute to both cardiovascular control during head movements (e.g., orthostatic reflexes) and autonomic manifestions of vestibular dysfunction, motion sickness and exposure to altered gravitational environments.

Animals↗
PubMed1994

Organization of vestibular nucleus projections to the caudal dorsal cap of kooy in rabbits.

This study used retrograde and anterograde tracing methods to characterize the origin and terminal distribution of vestibular nuclear projections to the caudal dorsal cap of the inferior olive in albino rabbits. Comparisons of the retrograde labeling patterns from Cholera toxin B fragment-horseradish peroxidase and Fluoro-Gold injection sites centred in either the caudal dorsal cap or the rostral dorsal cap plus ventrolateral outgrowth revealed that they receive projections from different vestibular nuclear regions. Tracer injections in the rostral dorsal cap and ventrolateral outgrowth produced a sparse bilateral distribution of labeled neurons in the superior vestibular nucleus and an almost exclusively ipsilateral pattern of labeled neurons in caudal pars alpha of the lateral vestibular nucleus. Injections in the caudal dorsal cap, though, labeled neurons bilaterally in the rostral medial vestibular nucleus, predominantly ipsilaterally in pars beta of the lateral vestibular nucleus and almost exclusively ipsilaterally in caudal pars alpha of the lateral vestibular nucleus and the rostral aspect of the inferior vestibular nucleus. Vestibular nucleus injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin indicated (1) that a predominantly ipsilateral projection to the caudal dorsal cap originates bilaterally from the pars beta of the lateral vestibular nucleus and the rostroventral aspect of the rostral medial vestibular nucleus, (2) that the medial half of the caudal medial vestibular nucleus is the source of a predominantly contralateral projection to dorsal cap, (3) that the caudal aspect of nucleus prepositus hypoglossi contributes a predominantly ipsilateral projection to the medial accessory olive and (4) that the rostral aspect of inferior vestibular nucleus and the dorsal and lateral aspects of the caudal medial vestibular nucleus project to nucleus beta of the medial accessory olive. In addition, axons containing anterogradely transported PHA-L were observed bilaterally in the oculomotor and abducens nuclei from injection sites involving pars beta of the lateral vestibular nucleus. It is hypothesized that bilateral vestibulo-caudal dorsal cap pathways coordinate activity in the left and right flocculus and nodulus during horizontal head movements to facilitate the performance of conjugate vestibulo-ocular and optokinetic reflexes.

Animals↗
PubMed1994

Organization of vestibular inputs to nucleus tractus solitarius and adjacent structures in cat brain stem.

The vestibular system is involved in maintaining stable blood pressure and respiration during changes in posture and is essential for eliciting motion sickness-related vomiting. Because the nucleus tractus solitarius (NTS) participates in the regulation of sympathetic and inspiratory outflow and the triggering of emesis, we tested the hypothesis that this region receives vestibular inputs in cats. In one set of experiments, microinjections of the tracer Phaseolus vulgaris leucoagglutinin into the medial and inferior vestibular nuclei labeled projections to the middle and lateral regions of the NTS. In electrophysiological experiments, electrical stimulation of the vestibular nerve modified the firing rates of neurons located in the same regions. Some neurons with vestibular inputs received convergent signals from the abdominal vagus nerve and could potentially mediate motion sickness-related vomiting. Others received convergent baroreceptor inputs and could act as a substrate for some components of vestibulosympathetic reflexes. In contrast, inspiratory neurons in the dorsal respiratory group received little vestibular input, suggesting that vestibulorespiratory reflexes are mediated by cells located elsewhere.

Animals↗
PubMed1993

Immunohistochemical demonstration of regionally selective projections from locus coeruleus to the vestibular nuclei in rats.

This study describes a regionally selective projection of tyrosine hydroxylase and dopamine beta-hydroxylase-immunoreactive fibers from locus coeruleus (LC) and the A4 region of nucleus subcoeruleus to the vestibular nuclear complex in Long-Evans and Sprague-Dawley rats. These fibers travel in two distinct pathways. A lateral descending noradrenergic bundle provides input from LC to the superior vestibular nucleus (SVN), the cochlear nuclei, and the cerebellar cortex. A medial descending noradrenergic bundle provides input to the lateral vestibular nucleus (LVN), medial vestibular nucleus (MVN), and the inferior vestibular nucleus (IVN) before continuing on to the cochlear and cerebellar nuclei. The terminal plexus of these fibers varies markedly across these vestibular nuclear regions. Immunoreactive axons form a dense plexus around somata and proximal dendrites of Deiters' neurons in dorsal LVN. The axon plexus is less dense in SVN and ventral LVN, and relatively sparse in MVN and IVN. This regional selectivity of noradrenergic innervation suggests that central adrenergic systems may selectively modulate vestibulospinal reflexes at the level of the vestibular nuclear complex.

Animals↗
PubMed1992

A "beat-to-beat" interval generator for optokinetic nystagmus.

An analysis of optokinetic responses was used to derive an iterative model that reproduces the duration of nystagmus slow phases and eye position control during optokinetic nystagmus. Optokinetic nystagmus was recorded with magnetic search coils from red-eared turtles (Pseudemys scripta elegans) during monocular, random dot pattern stimulation at constant velocities ranging from 0.25-63 degrees/s. The beat-to-beat behavior of slow phase durations was consistent with the existence of an underlying neural clock, termed the basic interval generator, that is based on an integrate-to-fire neuron model. This hypothetical basic interval generator produces an interval that is the product of the duration of the previous interval and a mean 1 truncated normal variate with variance sigma 2. Data analyses indicated that the initial value of the interval generator during a period of nystagmus, termed tau 0, is proportional to the inverse square root of slow phase eye velocity. Further, if the eye was deviated in the slow phase direction (re mean eye position) when the slow phase began, the slow phase duration was consistent with a single cycle of the basic interval generator. However, if the eye was deviated in the fast phase direction, the distribution of the durations of the ensuing slow phases indicated that a proportion of the slow phases were produced by more than one cycle of the basic interval generator. This phenomenon is termed "skipping a beat" and occurs with probability Ps. Finally, the amplitude of fast phases behaved as a linear function of eye position at the fast phase onset and the product of tau 0 and slow phase eye velocity. A computer simulation reproduced the observed distribution of slow phase durations, the proportion of fast phases in the fast phase and slow phase directions and the distribution of eye positions at the onset and end of fast phases. This novel model suggests that both timing and eye position information contribute to the alternation of nystagmus fast and slow phases.

Animals↗