Intra-amniotic pharmacological blockade of inflammatory signalling pathways in an ovine chorioamnionitis model.

Intrauterine inflammation (IUI) associated with infection is the major cause of preterm birth (PTB) at <32 weeks' gestation and accounts for ∼40% of all spontaneous PTBs. Pharmacological strategies to prevent PTB and improve fetal outcomes will likely require both antimicrobial and anti-inflammatory therapies. Here we investigated the effects of two cytokine-suppressive anti-inflammatory drugs (CSAIDs), compounds that specifically target inflammatory signalling pathways, in an ovine model of lipopolysaccharide (LPS)-induced chorioamnionitis. Chronically catheterized ewes at 116 days gestation (n = 7/group) received an intra-amniotic (IA) bolus of LPS (10 mg) plus vehicle or CSAIDS: TPCA-1 (1.2 mg/kg fetal weight) or 5z-7-oxozeaenol (OxZnl; 0.4 mg/kg fetal weight); controls received vehicle (dimethylsulphoxide). Amniotic fluid (AF), fetal and maternal blood samples were taken 0, 2, 6, 12, 24 and 48 h later; tissues were taken at autopsy (48 h). Administration of TPCA-1 or OxZnl abrogated the stimulatory effects of LPS (P < 0.01 versus vehicle control) on production of PGE2 in AF, with lesser (non-significant) effects on IL-6 production. Fetal membrane polymorphonuclear cell infiltration score was significantly higher in LPS versus vehicle control animals (P < 0.01), and this difference was absent with TPCA-1 and OxZnl treatment. LPS-induced systemic fetal inflammation was highly variable, with no significant effects of CSAIDs observed. Lung inflammation was evident with LPS exposure, but unaffected by CSAID treatment. We have shown in a large animal model that IA administration of a single dose of CSAIDs can suppress LPS-induced IA inflammatory responses, while fetal effects were minimal. Further development and investigation of these compounds in infectious models is warranted.

Induction of necrosis and cell cycle arrest in murine cancer cell lines by Melaleuca alternifolia (tea tree) oil and terpinen-4-ol.

PURPOSE: To examine the in vitro anticancer activity of Melaleuca alternifolia (tea tree) oil (TTO), and its major active terpene component, terpinen-4-ol, against two aggressive murine tumour cell lines, AE17 mesothelioma and B16 melanoma. METHODS: Effects of TTO and terpinen-4-ol on the cellular viability of two tumour cell lines and fibroblast cells were assessed by MTT assay. Induction of apoptotic and necrotic cell death was visualised by fluorescent microscopy and quantified by flow cytometry. Tumour cell ultrastructural changes were examined by transmission electron microscopy and changes in cell cycle distribution were assessed by flow cytometry, with changes in cellular morphology monitored by video time lapse microscopy. RESULTS: TTO and terpinen-4-ol significantly inhibited the growth of two murine tumour cell lines in a dose- and time-dependent manner. Interestingly, cytotoxic doses of TTO and terpinen-4-ol were significantly less efficacious against non-tumour fibroblast cells. TTO and terpinen-4-ol induced necrotic cell death coupled with low level apoptotic cell death in both tumour cell lines. This primary necrosis was clarified by video time lapse microscopy and also by transmission electron microscopy which revealed ultrastructural features including cell and organelle swelling following treatment with TTO. In addition, both TTO and terpinen-4-ol induced their inhibitory effect by eliciting G1 cell cycle arrest. CONCLUSION: TTO and terpinen-4-ol had significant anti-proliferative activity against two tumour cell lines. Moreover, the identification of primary necrotic cell death and cell cycle arrest of the aggressive tumour cells highlights the potential anticancer activity of TTO and terpinen-4-ol.

Subjective visual vertical in patients with benign paroxysmal positional vertigo.

The ocular tilt reaction leads to an alteration in the subjective visual vertical (SVV). Nonsurgical peripheral vestibular dysfunction only rarely leads to changes in the SVV. To our knowledge, no studies have examined the effects on the SVV in patients with benign positional paroxysmal vertigo (BPPV) post Hallpike and Semont maneuvers. Sixteen patients with posterior canal BPPV were assessed in the vestibular clinic in Winnipeg, Manitoba. These patients had assessment of their SVV at baseline, post Hallpike and Semont maneuvers, and at follow-up 2 weeks later. These patients were also compared to a control group (n = 9). Ten of 16 patients showed a statistically significant change in SVV post Hallpike maneuver. An even larger number of patients, 14 of 16, showed a significant difference when compared to the control group post Hallpike. These findings suggest that the inferior vestibular nerve may to some degree influence the ocular tilt reaction.

Decision matrix analysis for tonic ocular torsional abnormalities with posturography abnormalities.

Tonic ocular torsions can arise from a variety of central or peripheral, vestibular, and nonvestibular lesions. However, the role of tonic ocular torsions in neurotology has been limited to surgical patients after unilateral vestibular deafferentation. By using 12 patients with a spectrum of well-defined unilateral peripheral vestibular lesions confirmed by electronystagmography (ENG), we identified a link between ipsiversive tonic ocular torsion compensation and vestibulospinal compensation, as measured by computerized dynamic posturography. In the context of ENG findings and posturography, the differential diagnosis of ocular torsions may be localized to the otoliths by using a decision matrix. Specifically, conditions of absent vision and sway-referenced support on computerized dynamic posturography associated with concurrent static ocular torsional abnormalities may suggest an otolith disorder. Furthermore, static ocular torsion assessment provides another important window on central vestibular compensation.

Ocular torsion monitoring in chemical labyrinthectomy.

OBJECTIVE: To study the usefulness of ocular torsion analysis as an adjunct to examining central vestibular compensation. DESIGN: Prospective evaluation. SETTING: The Vestibular Disorders Clinic, University of Manitoba Health Sciences Centre. METHODS: Seven patients with intractable Meniere's disease underwent elective transtympanic gentamycin labyrinthectomy. Serial examination of patient progress was performed using fundus photography, subjective visual vertical estimations, electronystagmography, and audiometry. RESULTS: Ocular torsion analysis reveals unexpected initial and early contraversive torsion behaviour in some patients, which may represent an early irritative phenomenon stemming from either the gentamicin or the Meniere's disease itself. CONCLUSION: Despite the sensitivity of the ocular torsion measures, there appears to be no useful predictive correlation between ocular torsion and audiometric functioning that might predict impending hearing loss. Nevertheless, ocular torsion analysis reveals subtle changes in vestibular system functioning and may provide useful adjunctive information in the assessment of vestibular ototoxicity.

Post-treatment instructions in the nonsurgical management of benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is the commonest peripheral vestibular disorder seen in dizziness clinics. It was long believed that the condition was caused by inorganic particles in the cupula of the posterior semicircular canal (PSC). More recently it has been suggested that BPPV may result from free-floating densities in the endolymph of the long arm of the PSC. Among the various treatment modalities used, two maneuvers, each based on a different theory of pathogenesis, have reported equally high success in the control of this disorder. These maneuvers are customarily followed by strict post-treatment instructions. We studied patients with BPPV prospectively by comparing the therapeutic effectiveness of these two modalities and studying the importance of post-treatment instructions in affecting the final outcome in each modality. We showed that both maneuvers were equally successful in controlling the symptoms and that post-treatment instructions were not necessary.

Dizziness Handicap Inventory correlates of computerized dynamic posturography.

To assess the handicapping effect of dizziness related to posture and balance, the Dizziness Handicap Inventory (DHI) and Computerized Dynamic Posturography (CDP) were used to assess 101 consecutive patients referred for neurotologic evaluation of dizziness. Most patients, regardless of diagnosis, related some level of preexisting handicap, most often in the DHI Physical subscale. Generally, females and patients with bilateral lesions scored higher in all DHI subscales. No clinically useful correlations emerged between DHI and CDP testing, although DHI scores were marginally higher for patients failing CDP conditions. Functional balance ability could not be correlated with patient handicap, but a literature review suggests that the desynchrony between dizziness signs and symptoms may be related to underlying patient anxiety and differences in coping strategies.

Vestibular evoked myogenic potentials.

A pilot study was undertaken in our Vestibular Disorders Clinic to re-evaluate the clinical benefits of vestibular evoked myogenic potentials (VEMP). In seven normal subjects and 20 documented unilateral peripheral vestibular disorder patients, electromyograms were recorded from surface electrodes over the sternomastoid muscles and averaged in response to 0.1-millisecond clicks played through headphones. Control patients demonstrated EMG positive-negative potentials (p14-n21) of equivalent latencies and amplitudes both ipsilateral and contralateral to the stimuli. In patients with documented unilateral peripheral vestibular disorders, the p14-n21 potentials were preserved in the presence of sensorineural hearing loss and absent in those patients with partial or total vestibular loss. A high directional correlation is noted between the p14-n21 potential and gold-standard caloric testing. We suspect the origin of the response may be in the saccule and suggest that VEMP testing may be useful in assessing intact vestibulocollic pathways in humans.

Comparison of different exercise programs in the rehabilitation of patients with chronic peripheral vestibular dysfunction.

The purpose of this study was to evaluate the effects of two exercise programs on balance performance in patients with chronic peripheral vestibular dysfunction and to assess whether these exercise programs induce adaptive modifications of the vestibulo-ocular reflex (VOR). Patients were randomly assigned to one of two groups. (1) Those in the Rehab (Reh) group (n = 11) received a comprehensive exercise program that consisted of balance retraining and goal-directed eye-head exercises under combinations of varied visual and somatosensory sensory conditions. Patients received 45-minute training sessions, three times per week for 12 weeks, and were instructed on a custom home exercise program. (2) Those in the Home group (n = 12) were instructed to perform the Cooksey-Cawthorne eye-head exercises at home, on a daily basis, for 12 weeks. In addition, after completion of the exercise program and a follow-up period, 7 of the participants in the Home group (here defined as the A group) chose to enter the Reh program (here defined as the B group). Balance performance was assessed by measuring the peak-to-peak magnitude and total amount of anterior-posterior body sway, and of horizontal (shear) ground reaction force during six test conditions, in which visual and somatosensory orientation cues were reduced or altered by rotation of the visual surround or support surface in proportion to the subject's sway, and in which vision was eliminated (eyes closed). The VOR response to step chair rotations of 60 degrees/s and 120 degrees/s, and the optokinetic reflex (OKN) response to 60 degrees/s constant velocity optokinetic stimuli were recorded. Left-right difference in VOR gain, VOR time constant, and OKN gain were determined. These tests were performed 1 day prior to start of treatment (TD 1), 6 weeks after start of treatment (TD 2), at the end of the 12-week treatment period (TD 3), and 5 months after end of treatment (TD 4). The findings revealed a significant improvement in standing balance performance under dynamic conditions for patients in the Reh program (Reh and B groups) but not for patients performing the eye-head exercise (Home or A groups). Thus, even in patients with chronic vestibular dysfunction, compensation for the loss or disruption of peripheral vestibular inputs can be effectively induced by exercises that provide sensory feedback appropriate for behavioral changes involving sensory substitution or sensory-motor reorganization.(ABSTRACT TRUNCATED AT 400 WORDS)

Unilateral vestibular deafferentation: a model of adaptation.

After acute loss of peripheral vestibular function, a centrally adaptive process takes place. Clinical measurements of vestibular adaptation are useful, both diagnostically and as a means of following patients after acute vestibular deficits. Ocular torsion is one measurement that can be used to follow these acutely disabled patients. The measurement is made from fundus photographs and is technically easy to perform and interpret. We present a pilot study from our Vestibular Disorders Clinic using fundus photography to measure the optic nerve head-foveal angle in six patients undergoing unilateral vestibular neurectomy, with subsequent analysis resulting in a speculative mathematical model of vestibular compensation in the roll plane. While the identification or selection of patients with significant ocular torsions from the vestibular population remains ill-defined, fundus photography remains an easy and useful method of following compensation in postoperative patients.

Human vertical optokinetic nystagmus and after-response, and their dependence upon head orientation with respect to gravity.

Characteristics of human vertical optokinetic nystagmus (VOKN) and afternystagmus (VOKAN) were examined by electro-oculography in 18 normal human subjects by means of the analysis of slow phase velocity (SPV) and area under the regression curve of the VOKAN decay. Under normal gravity, subjects were tested in upright and left ear down (90 degrees roll) positions, respectively, using a hemisphere onto which stripes were projected at a velocity of 40 degrees/s in left, right, up and down directions. Analysis of the VOKN and VOKAN revealed a significant asymmetry of vertical eye movements in the subjects' sagittal plane, ie, stronger upward SPV than downward in both VOKN and VOKAN decay. This asymmetry became even more prominent when the head was in the 90 degrees roll position. It is postulated that the asymmetry of VOKN and VOKAN in humans, as in animals, is due to the asymmetrical storage capability of the vertical velocity storage mechanism which mainly contributes to upward eye movements. In addition, it is postulated that the vertical storage mechanism is modified by the action of gravity on the otolith organs. However, only two out of our 18 subjects demonstrated cross-coupling, as reported in animals, from the horizontal to the vertical mode of storage when the head was tilted away from the spatial vertical.

Stimulus velocity dependence of human vertical optokinetic nystagmus and afternystagmus.

Stimulus velocity dependence of human VOKN and VOKAN was investigated using 20 degrees, 40 degrees, 60 degrees, and 80 degrees/s optokinetic stimulation. In our experimental conditions, 40 degrees/s was found to be the most appropriate stimulus velocity for inducing reliable VOKN and VOKAN based on the analysis of SPV, gain, and the area under the VOKAN decay curve. There was a clear trend toward up/down asymmetry of VOKN gain, with higher upward OKN SPV than downward at 40 degrees/s. VOKAN with both short and long time constant components was induced in 5 of 11 subjects, but only when the stimulus was upgoing. Stimulation at 20 degrees/s in either direction produced a decay with only a short time constant. VOKN-SPV and the area under VOKAN decay curve at 40 degrees/s showed no significant difference from the corresponding values at 60 degrees/s or 80 degrees/s, indicating that following and the velocity storage mechanism had saturated at 40 degrees/s. However, the gain at 60 degrees/s and 80 degrees/s became low and eye movement regularity was poor. Stimulation at 20 degrees/s may activate mainly the vertical pursuit mechanism, as it did not produce up/down asymmetry. It is proposed that, as in the horizontal case, two kinds of mechanisms are involved in vertical stripe-following eye movements, which represent smooth pursuit and optokinetic systems respectively.

Suppression of optokinetic velocity storage in humans by static tilt in pitch.

The effects of static tilts about the pitch axis on human horizontal optokinetic after-nystagmus OKAN (HOKAN) were examined. Static tilts in pitch produced tilt-dependent HOKAN suppression. The slow decay (indirect pathway) component (coefficient C and long time constant 1/D) of the two-component model for OKAN was significantly reduced, while the short decay (direct pathway) component (coefficient A and short time constant 1/B) remained invariant as angle of tilt was increased. These results provide further evidence that otolith organ activity can couple to horizontal velocity storage in humans, in accordance with models proposed in the literature.

Suppression of optokinetic velocity storage in humans by static tilt in roll.

The effects of static tilts about the roll (anterior-posterior) axis on human horizontal optokinetic afternystagmus (HOKAN) were examined. Static tilts in roll, with subjects lying on their left side, produced significant tilt-dependent HOKAN suppression. Only the slow (indirect pathway) component time constant (1/D) of the double exponential model for human HOKAN decreased with angle of roll tilt. The effect was direction specific in that suppression occurred only following a leftward-going stimulus. These findings provide further support for the postulate that otolith-organ-mediated activity can couple to the horizontal velocity storage mechanism in humans. A slight trend towards a tilt-dependent reduction of coefficient A (initial slow phase velocity of fast component decay) was revealed, suggesting the possibility that otolith-organ-mediated activity could couple to direct (pursuit-mediated?) pathways as well. No horizontal-to-vertical cross-coupling occurred, indicating that this aspect of the 3-dimensional model for velocity storage proposed by Raphan & Cohen (1988) may not completely apply to humans.

Effect of active head movements about the pitch, roll, and yaw axes on human optokinetic afternystagmus.

Effects of active head movements about the pitch, roll, or yaw axes on horizontal optokinetic afternystagmas (OKAN) were examined in 16 subjects to test the hypothesis that otolith organ mediated activity induced by a change in head position can couple to the horizontal velocity storage in humans. Active head movements about the pitch axis, forwards or backwards, produced significant OKAN suppression. Pitch forward head movements exerted the strongest effect. Active head movements about the roll axis towards the right also produced OKAN suppression but only if the tilted position was sustained. No suppression was observed following sustained yaw. However, an unsustained yaw left movement after rightward drum rotation significantly enhanced OKAN. Sustained head movement trials did not significantly alter subsequent control trials. In contrast, unsustained movements about the pitch axis, which involve more complex interactions, exerted long-term effects on subsequent control trials. We conclude that otolith organ mediated activity arising from pitch or roll head movements couples to the horizontal velocity storage in humans, thereby suppressing ongoing OKAN. Activity arising from the horizontal canals during an unsustained yaw movement (observed mainly with yaw left), following drum rotation in a direction contralateral to the movement, may also couple to the velocity storage, resulting in increased activity instead of suppression.

Convergent effects from vestibulospinal tract and primary cutaneous afferent fibers on motoneurons to proximal lower limb flexor and extensor muscles in humans.

In human subjects, the latency and magnitude of cutaneomuscular test reflexes, evoked by stimulation of the sural nerve in the contralateral and ipsilateral quadricep and hamstring muscles, were investigated during static tilts in the pitch axis. The ANOVA demonstrated a highly significant, tilt-dependent modulation of the magnitude of the test reflex for the initial phase of both ipsilateral quadriceps and ipsilateral hamstrings. These results are consistent with results from a similar study on human ankle muscles and provide further evidence that the tilt-dependence of these cutaneomuscular reflexes originates from activity in the otolith receptors.

Convergent effects from vestibulospinal tract and primary cutaneous afferent fibers on motoneurons to ankle extensor and flexor muscles in humans.

The latency and magnitude of cutaneomuscular reflexes, evoked by stimulation of the sural nerve in the contralateral and ipsilateral tibialis anterior and soleus, were investigated in normal human subjects during static tilts in the pitch axis. For all subjects the test reflex consisted of oscillating sequences of excitation and inhibition, each muscle exhibiting a characteristic pattern defined by its latency and sign of the initial phase. The latency of the various components and the sign of the initial phase did not vary with angle of tilt. However, the results of an ANOVA demonstrate a highly significant tilt-dependent modulation of the amplitude of the test reflex for the initial inhibitory phase of the contralateral tibialis anterior. We propose that this tilt-dependent effect on the crossed cutaneomuscular reflex originates from activity in the otolith organ receptors.

Human optokinetic afternystagmus. Is the fast component of OKAN decay due to smooth pursuit?

Eye movement after-effects subsequent to pursuit of a single LED target were studied in human subjects to test the hypothesis that constant velocity pursuit activates a velocity storage system in the neuronal pathway. The temporal characteristics of observed after-effects fall within those predicted from the Robinson model of eyeball mechanics, indicating that neuronal integration was not a factor.