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B J Winterson

Publications and source records attributed to B J Winterson.

16 recordsLinked to original sources
PubMed2000

The effects of manually applied intermittent pulsation pressure to rat ventral thorax on lymph transport.

The present study evaluated the effects of tissue massage on a part of the body remote from the region of lymph uptake into the initial lymphatics. Lymph uptake was assessed with a fluorescent probe placed in a potential space of the lower extremity of anesthetized female Sprague-Dawley rats. Tail blood was assayed at intervals over 15 hours for fluorescence. A total of 63 animals were utilized (treatment = 32 and control = 31). The manipulated group received lymph flow enhancing treatment (LFET) five minutes per rat per hour until they were aroused. The control group were left lying prone in cages until a blood sample was taken. The LFET procedure was bilateral finger pressure applied to the lower ribs of a supine rat followed immediately by a light tap to the sternum. These maneuvers were repeated for 5 minutes. The rate of appearance of fluorescent probe was greater during the first nine hours of the experiment in the treatment group than in the controls but not at hours 12 and 15. This study demonstrates that mechanical pressure to body regions physically distant from the location of lymph formation enhances lymph uptake.

Animals↗
PubMed1995

Properties of peripherally induced persistent hindlimb flexion in rat: involvement of N-methyl-D-aspartate receptors and capsaicin-sensitive afferents.

In the sodium pentobarbital anesthetized rat, percutaneous electrical stimulation (2 mA, 7 ms, 100 Hz, 60 min) across the upper hindlimb produces an ipsilateral hindlimb flexion that persists following spinal transection. Using this preparation, the following were found. (1) Flexion was observed in both the intact and acutely spinalized (T7) rat 10 hours to two weeks following induction, but was negligible at six weeks. (2) Pretreatment of intact rats with the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists, ketamine HCl and MK-801, reduced persistent hindlimb flexion in a dose-dependent manner. (3) Pretreatment of spinalized rats with MK-801 reduced the amount of flexion, observed at 30 min following stimulation. However at 72 hrs following stimulation, administration of MK-801 to acutely spinalized rats had no effect on flexion. (4) Capsaicin pretreatment, of either neonates or adults, reduced the amount of flexion observed at 30 min following stimulation, but only adult capsaicin pretreatment reduced flexion at 72 h. (5) At 72 h following induction, bilateral dorsal rhizotomy (T11-L6) of acutely spinalized rats had no significant effect on flexion when compared to pre-rhizotomy levels. However, the subsequent removal of the hindlimb skin produced a significant reduction in flexion, and the remaining flexion was eliminated by the removal of the thoracolumbar spinal cord and cauda equina. These combined results suggest that prolonged activation of C-afferents and NMDA receptors induce a persistent hindlimb flexion in rat that is maintained at the level of the spinal cord.

Afferent Pathways↗
PubMed1992

Intrathecally administered N-methyl-D-aspartate increases persistent hindlimb flexion in rat.

Persistent hindlimb flexion was induced in pentobarbital anesthetized rats using a prolonged, electrical stimulus. Intrathecal (i.t.) N-methyl-D-aspartate NMDA) (1 mM, 5 microliters) applied prior to stimulation increased flexion relative to stimulated controls subsequent to stimulation (156%); 3 days later (109%) and after spinalization at 3 days (91%). Pretreatment with MK-801 (3 mg/kg, i.p.) prevented the enhancement of flexion. Withdrawal latencies to a thermal stimulus also were measured. I.t. NMDA plus stimulation reduced mean latency relative to controls only subsequent to stimulation. Latencies were increased by MK-801 post-injection, post-stimulation and at 3 days. The results suggest that the induction of persistent hindlimb flexion depends upon spinal NMDA receptors.

Animals↗
PubMed1992

Behaviors induced by 5-hydroxytryptophan in neonatal, preweaning, postweaning, and adult Sprague-Dawley rats.

The behaviors induced by the 5-hydroxytryptamine (5-HT) precursor 5-hydroxytryptophan (5-HTP) has been called the "5-HT (serotonin) syndrome." These behaviors and others identified in rat pups were observed following administration of 5-HTP (300 mg/kg, SC) on postnatal (PN) days 3, 14, and 28 and in adult rats. Certain 5-HT syndrome behaviors and other uniquely neonatal behaviors were present in PN3 pups treated with vehicle. 5-HTP-treated PN3 pups showed increased head-shakes, rollovers, vocalizations, and forepaw treading and decreased hindlimb abduction. No 5-HT syndrome or neonatal behaviors were present at PN14 or PN28 or in adults treated with vehicle. 5-HTP administered at PN14 stimulated circling, forepaw treading, and resting tremor; at PN28, stimulated head-shakes and resting tremor; and in adults produced only head-shakes. To determine if prior exposure to 5-HTP affected the sensitivity of 5-HT receptor subtypes, the 5-HT1A agonist (+/-)-8-hydroxy-dipropylaminotetralin (8-OH-DPAT) and the 5-HT2/1C agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) were administered to all rats as adults. 8-OH-DPAT (1 mg/kg, SC) produced flattened body posture unaffected by prior exposure to 5-HTP. Head-shakes induced by DOI (5mg/kg, IP) were decreased by prior exposure to 5-HTP at PN3 and adult, but increased by preexposure at PN28. Thus, serotonergic neural systems are implicated in some behaviors of neonates. The developmental patterns suggest changes in the sensitivity to these systems. Further, lasting changes in 5-HT2/1C receptor sensitivity occur due to exposure to 5-HTP.

5-Hydroxytryptophan↗
PubMed1991

Inhibition of chronic hindlimb flexion in rat: evidence for mediation by 5-hydroxytryptamine.

Prolonged high-intensity stimulation of the rat hindlimb produces a persistent unilateral flexion. 5-Hydroxytryptamine (5-HT) has been implicated in the modulation of spinal cord mechanisms. Electrical stimulation across the upper hindlimb was used to induce a persistent hindlimb flexion. The flexion was measured after stimulation and at 72 h, both before and after spinal transection at T7. Transection of the spinal cord typically resulted in an increase in flexion of 3-5 g (rebound). Pretreatment with para-chlorophenylalanine (pCPA) to deplete 5-HT, or the administration of metergoline, a non-specific 5-HT antagonist, had no significant effect on flexion at 72 h in the intact rat but abolished rebound. The 5-HT1A agonist, (+-)-8-hydroxy-2-(di-N-propylamino)tetralin hydrobromide (8-OH-DPAT) and 5-HT1B agonist, m-trifluoromethylphenylpiperazine-HCl (TFMPP), had no effect on flexion at 72 h in the intact rat but reduced rebound. The 5-HT2 agonist, 1-(2.5-dimethoxy-4-iodophenyl)-2-aminopropane-HCl (DOI), suppressed post-stimulation flexion and flexion subsequent to spinal section. Furthermore, ketanserin, a 5-HT2 antagonist, restored flexion suppressed by DOI in the acutely spinalized rat. These results suggest that chronic hindlimb flexion is suppressed in the intact rat by descending, serotonergic fibers which exert an effect through spinal 5-HT2 receptors. Moreover, 5-HT1 agonist suppression of rebound implicates these receptors as well in the modulation of chronic hindlimb flexion.

Animals↗
PubMed1985

Direction-selective single units in the nucleus lentiformis mesencephali of the pigeon (Columba livia).

The receptive field properties of single units within the nucleus lentiformis mesencephali (LM) of the pigeon were studied using electrophysiological methods. Previous studies have suggested that the avian LM may be homologous to the nucleus of the optic tract (NOT) in mammals. Single units in the pigeon LM are similar to mammalian NOT units in that they are direction-selective, mostly for horizontal directions, velocity-selective, have large visual receptive fields and respond preferentially to large stimuli with many visual contrasts. In contrast to most reports of NOT units of mammals, more than half of pigeon LM units prefer high velocities (greater than 10 degrees/s), a large proportion (0.37) prefer non-horizontal directions, and receptive fields that are retinotopically arranged within the LM. The response properties of pigeon LM units are compared to the response properties of units within the accessory optic nucleus (the nucleus of the basal optic root or nBOR). In the avian brain, nBOR neurons respond at low velocities (0.5-5 degrees/s) and respond predominantly to vertical stimulus movement whereas LM units respond over a broader range of velocities (0.2-80 degrees/s) and respond predominantly to horizontal movements. Thus, the LM and nBOR may play different roles in the control of compensatory eye movements.

Animals↗
PubMed1981

Inversion of direction-selectivity to anterior fields in neurons of nucleus of the optic tract in rabbits with ocular albinism.

Extracellular recordings were made of 46 well-isolated single units in the nucleus of the optic tract (NOT) from 27 rabbits which were paralyzed but unanesthetized. Rabbits were selected from 3 varieties with ocular albinism. These units showed short latencies (mean = 2.2 msec, S.D. = 0.4) to chiasmic stimulation suggestive of monosynaptic innervation from retinal ganglion cells. Receptive fields were large and receptive field centers were confined to the projection of the visual streak. All units showed direction selectivity in which preferred stimulus motions were always nearly horizontal in the anterior or posterior direction. The direction selectivity of the units was broad in that excitatory acceptance angles were 180 degrees. Single units recorded from NOT in albino rabbits could be classified into 4 types based on regions of direction selectivity. The most common (64%) type of unit had receptive fields with two regions of opposed direction selectivity. The preferred direction of motion was anterior in lateral and posterior visual fields and was posterior in anterior visual fields. Two smaller groups of units (13% and 11%) had receptive fields with only one preferred direction. When the receptive field was anterior, the preferred direction was posterior. When the receptive field was lateral or posterior, the preferred direction was anterior. The least commonly encountered type of unit (7%) had receptive fields with two regions of direction selectivity. Anterior visual fields gave rise to anterior direction selectivity and lateral and posterior visual fields gave rise to posterior direction selectivity. The characteristics of NOT units are similar to those described for NOT units in pigmented rabbits except for an inversion of direction selectivity to stimulation from anterior visual fields. NOT units in albino rabbits show posterior direction selectivity when stimulation arises from anterior visual fields. The difference in directional preference in the visual receptive fields of the units in the NOT of albino rabbit may be responsible for the inversion of optokinetic pursuit eye movements characteristic of albino rabbits.

Albinism↗
PubMed1980

Post-rotary nystagmus and optokinetic after-nystagmus in the rabbit linear rather than exponential decay.

The decay of the slow phase velocity of post-rotatory (PRN) and optokinetic (OKAN) after-nystagmus as a function of time was measured in Dutch rabbits after stimulation with velocity steps of 30, 60, and 150 degrees/s. The decays fitted linear functions very well, but only poorly exponential ones. Typical decay rates were 2-5 degrees/s2, with apparent time constants (defined by decay to 37% of initial velocity) in the order of 10-20 s. Within one animal, the decays of OKAN and PRN with similar initial velocities were indistinguishable. With sinusoidal oscillation, the time constant of the vestibulo-ocular reflex - estimated from phase lead - was only 2-3 s, and probably similar to the cupular time constant. In general, time constants increased when eye velocities increased. This indicates that the vestibulo-ocular reflex of the rabbit behaves as a non-linear system. A velocity storage system with a constant discharge rate is postulated as a main non-linear element. This would introduce a linear decay of velocity as well as a threshold for velocity. This storage system would be common to both vestibulo-ocular and optokinetic reflexes.

Animals↗
PubMed1978

Optokinetic eye movements in albino rabbits: inversion in anterior visual field.

When visual contrasts are restricted to the anterior sector (90 degrees to 180 degrees) of the albino rabbit's visual field, eye position is dramatically unstable, and when such contrasts are moved, horizontal optokinetic eye movements are inverted: the direction of pursuit is opposite to that of the stimulus. In the posterior visual field stability and optokinetic reactions are normal, as in all parts of the pigmented rabbit's visual field. This phenomenon may be one more of the complex of visual system defects linked to albinism.

Albinism↗
PubMedDate not supplied

Semicircular canal orientation in the adult resting rabbit.

Photographs of rabbits in the alert resting position were used to record head position. Semicircular canals were surgically exposed and points measured along each canal were used to compute the best-fit plane using a least-squares method. Computations of mean best-fit planes showed that the horizontal canals were not carried horizontally in the rabbit. The anteromedial edges were superior by 16 degrees. The anterior canals were vertically oriented and made an angle of 43 degrees to the sagittal plane. The posterior canal was tipped in the anterior direction slightly and also made an acute angle (26 degrees) with the frontal plane. Rabbit semicircular canals deviated significantly from orthogonality. The range was 86 degrees (anterior canals) to 133 degrees (posterior canals). Thus, there were no co-planar canals. Such semicircular canal geometry has implications for the neural circuitry controlling posture in the rabbit.

Animals↗