A new measurement of oesophago-gastric junction competence

Knowledge of the competence of the oesophago-gastric junction (OGJ) is fundamental to the understanding of gastro-oesophageal reflux disease (GORD), a disorder with a high incidence among the general population. A catheter with a bag 9.5 cms long mounted towards the distal end was swallowed by three volunteers. Using manometry readings and the point of respiratory inversion as a guide the probe was placed in the OGJ. The bag was distended with saline at a fixed rate volume before and after the administration of butylscopolamine to block cholinergic-mediated contractile smooth muscle activity. Using impedance planimetry three cross-sectional areas (CSA) measurements were made between three pairs of electrodes with 4 mm between each electrode on the catheter placed inside the ballon. Using the law of Laplace, CSA and pressure data could be calculated to give wall tension. Tension rose in all volunteers as the radius increased and it was higher towards the proximal end of the OGJ indicating that this measurement can be used to show the distensibility of the OGJ at different degrees of opening. This technique could be useful in identifying changes in the competence of the lower oesophageal sphincter in some patients with GORD.     

3D‐high resolution manometry of the esophagogastric junction

Background The esophagogastric junction (EGJ) is a complex structure that challenges accurate manometric recording. This study aimed to define EGJ pressure morphology relative to the squamocolumnar junction (SCJ) during respiration with 3D‐high resolution manometry (3D‐HRM). Methods A 7.5‐cm long 3D‐HRM array with 96 independent solid‐state pressure sensors (axial spacing 0.75 cm, radial spacing 45°) was used to record EGJ pressure in 15 normal subjects. Concurrent videofluoroscopy was used to localize the SCJ marked with an endoclip. Ex vivo experiments were done on the effect of bending the probe to match that seen fluoroscopically. Key Results 3D‐high resolution manometry EGJ pressure recordings were dominated by an asymmetric pressure peak superimposed on the lower esophageal sphincter (LES) attributable to the crural diaphragm (CD). Median peak CD pressure at expiration and inspiration (51 and 119 mmHg, respectively) was much greater in 3D‐HRM than evident in HRM with circumferential pressure averaging. Esophagogastric junction length, defined as the zone of circumferential pressure exceeding that of adjacent esophagus or stomach was also substantially shorter (2.4 cm) than evident in conventional HRM. No consistent circumferential EGJ pressure was evident distal to the SCJ in 3D‐HRM recordings and ex vivo experiments suggested that the intra‐gastric pressure peak seen contralateral to the CD related to bending the assembly rather than the sphincter per se. Conclusions & Inferences 3D‐high resolution manometry demonstrated a profoundly asymmetric and vigorous CD component to EGJ pressure superimposed on the LES. Esophagogastric junction length was shorter than evident with conventional HRM and the distal margin of the EGJ sphincteric zone closely correlated with the SCJ.     

The responses of dorsal horn neurones to controlled mechanical stimulation of the hindlimb skin in the rabbit

The functional characteristics and spatial arrangement of Type I mechanosensitive units found in the sural nerve of the anaesthetized rabbit have been investigated.There are approximately 108 Type I units innervating a skin area of about 59.1 cm² supplied by the sural nerve giving an innervation density of 1.83. This innervation density of 1.83 does not vary over the skin territory innervated by the sural. The dome/fibre ratio was 2.7.The domes were found to be distributed in a dispersed but fairly regular pattern. The average nearest neighbour distance was 5.3 mm. A stimulus of 5.5 threshold units showed the existence of a small receptive field of radius 2 mm surrounding each dome; at a 3 mm radius even the largest 2 mm indentation failed to evoke a response.The response of the Type I units exhibited 4 distinct phases:

1. (1) a dynamic phase

2. (2) a transient adaptive phase

3. (3) a highly irregular static phase

4. (4) an off phase. The impulse frequency/static displacement relationship was best fitted by a power function. The impulse frequency/velocity characteristic became horizontal at an average value of 15 μm/ms. A power function provided the best fit for this relationship.

The possible physiological significance of the differences between properties of Type I receptor populations in the rabbit and cat are discussed.     

Inhibition of dynamic thigh muscle contraction by electrical stimulation of the posterior cruciate ligament in humans.

We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh muscle during voluntary static and dynamic muscle contraction. The study group comprised nine young men with no history of injury to the knee joints. Multistranded Teflon-insulated stainless-steel wires were inserted into the PCL guided by ultrasound. In three subjects wires were also inserted into the fat pad of the knee. The PCL was electrically stimulated during static, concentric, or eccentric muscle contraction with a constant load of 20% of the maximal voluntary contraction of either the quadriceps or the hamstrings. Electromyographic signals were recorded with bipolar surface electrodes placed over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 HZ; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing muscle activity in both the quadriceps and hamstrings with latencies of 114-150 ms and 99-130 ms, respectively. Stimulation of the fat pad of the knee did not influence the muscle activity. The study suggests that the mechanoreceptors in the PCL are involved in controlling muscle activity during both static and active muscle contractions. The relative long latency of the reflex makes it unlikely that it can serve as a directly protective reflex for the cruciate ligaments.     

Chemical stimulation of the laryngopharynx increases Fos-like immunoreactivity in the rat hypothalamus and amygdala

Using immunohistochemical detection of the Fos protein as a cellular marker of neuronal activation, we examined forebrain areas that may be activated upon chemical stimulation of the laryngeal opening. Anesthetized rats were subject to multiple infusions of a chemical solution into the laryngopharynx. These animals were compared to two control groups: a surgical control group in which the animals were subject to the surgical procedure but received no stimulus infusions and a flow control group in which physiological saline replaced the chemical stimulus. Comparing the numbers of Fos-like-immunoreactive neurons in regions of the forebrain across groups revealed that infusing the chemical stimulus solution into the laryngopharyngeal opening selectively increased the number of Fos-like-immunoreactive nuclei in the paraventricular nucleus of the hypothalamus and the central nucleus of the amygdala, two autonomic-visceral related forebrain regions. Within the paraventricular nucleus of the hypothalamus, Fos-like-immunoreactive nuclei were significantly increased in the parvocellular subdivision while in the central nucleus of the amygdala, significant increases in Fos-like-immunoreactive nuclei were limited to the lateral capsular subdivision. These data suggest that in the rat laryngopharyngeal chemosensory stimulation activates forebrain regions that receive oral sensory information and are involved in visceral and autonomic functions.     

Morphology and somatotopic organisation of the central projections of afferents from tactile hairs on the hind leg of the locust.

The morphology and organisation of the central projections of tactile hair afferents from the hind leg of the locust, Schistocerca gregaria, were examined by staining individual hair afferents. Each tactile hair on the femur, tibia, and tarsus is innervated by a single sensory afferent, which projects to the ipsilateral half of the metathoracic ganglion. Afferents arborize in the ventralmost and lateral ventral association centres (vVAC and lVAC). The projections are organised somatotopically in a map with three axes, according to the position of the hair on the leg. First, proximo-distal: afferents from hairs on the proximal leg segments project more anteriorly than do those from hairs on distal leg segments. Moreover, on any given segment the afferents from the more proximal hairs project more anteriorly than do the afferents from the distal hairs. Second, antero-posterior: afferents from hairs on the posterior surface of the leg project more medially than do afferents from anterior hairs. Third, dorso-ventral: afferents from hairs on ventral parts of the leg project more ventrally than do afferents from the dorsal hairs. The afferents from posterior and anterior hairs project to an area between the central projections from dorsal hairs and ventral hairs. The position of a projection within the map is dependent upon the location of the hair on the leg and not the peripheral routes taken by the axon of its afferent to reach the ganglion.     

The effect of streptomycin on the neuromuscular junction of the frog

The neuromuscular block produced by streptomycin was studied in the frog sartorius muscle by means of intracellular recording and iontophoretic application of acetylcholine. Decreases of the end-plate potentials (e.p.p.s) and acetylcholine potentials (ACh potentials) were observed following the application of streptomycin. At a concentration of 10⁻⁴ M< the e.p.p. was36.8 ± 5.5%(mean ± S.E.) (n = 12), and the ACh potential was53.7 ± 3.8% (n= 12) of the control size. The resting membrane potential and membrane conductance of the muscle fibers were not affected by streptomycin. Streptomycin did not significantly alter the spontaneous prejunctional activity, but the amplitude of the miniature end-plate potentials (m.e.p.p.s) was decreased. After the application of higher concentrations of streptomycin, the quantum content decreased from the control value. It is suggested that the reduction of the e.p.p. amplitude produced by streptomycin is mainly due to a decrease in the sensitivity of the end-plate membrane. In addition, at higher concentrations, streptomycin reduced the amount of transmitter released from the motor nerve in response to a nerve volley.     

The effect of esomeprazole 20 mg twice daily on acoustic and perception parameters of the voice in laryngopharyngeal reflux

Background Randomized, placebo‐controlled studies have failed to demonstrate a significant treatment effect for laryngopharyngeal reflux (LPR) using traditional clinical endpoints. We compared the effect of esomeprazole 20 mg twice daily (b.i.d.) vs placebo on voice and acoustic‐related measures in patients with LPR. Methods Patients with LPR underwent endoscopy and pH testing. Subsequently, patients underwent videostroboscopic recordings of the larynx, acoustic voice and speech analysis. A voice use and quality diary and oesophageal symptom diary were completed at baseline. Thereafter, patients were randomized to esomeprazole 20 mg twice daily vs placebo for 3 months. The voice use and quality diary and oesophageal symptom dairy were repeated during the last week of treatment. Videostroboscopy and acoustic voice and speech analysis were also performed at the end of treatment. Key Results Twenty‐four patients were randomized to the esomeprazole group and 17 to the placebo group. There was no significant difference in videostroboscopic reflux finding scores from baseline to post‐treatment. Acoustic measures also failed to demonstrate significant differences within the same or between groups, even when a sub‐group analysis of patients with endoscopically documented oesophageal inflammation at baseline was performed. Additionally, no significant differences were found between groups when using voice use and quality diary. Conclusions & Inferences Use of more specific laryngeal functional parameters such as voice‐related acoustic measures of pitch range, fundamental frequency and intensity also failed to demonstrate a significant response to proton pump inhibitor treatment as compared to placebo in patients with suspected LPR.     

The effect of sciatic nerve stimulation on spinal cord blood flow.

Focal spinal cord blood flow was measured in the left dorsal column during left sciatic nerve stimulation, and compared to blood flow in the same area during sciatic nerve inactivity. Blood flow was found to be significantly increased during stimulation. It is suggested that this increased blood flow is a reflection of increased metabolic demands of the neurons and synaptic systems within the internuncial neural pools, activated by stimulation of all components of the sciatic nerve, rather than a reflection of increased non-synaptic axonal conduction in the dorsal column.     

The effect of quadriceps-electrocutaneous stimulation on the T-reflex and the H-reflex of the soleus muscle.

OBJECTIVE: To investigate the effect of ipsilateral quadriceps-electrocutaneous stimulation on the T-reflex and the H-reflex of the soleus muscle, and to examine the interactions in human cutaneous sensation - the soleus motoneuron pathway. METHODS: The T-reflex and H-reflex tests were performed bilaterally on 50 able-bodied adults with a standardized technique using the soleus muscle. The reflexes were conditioned by electrocutaneous stimuli applied to the ipsilateral quadriceps using the optimal transcutaneous electrical nerve stimulation (TENS) machine (3 x perception, intensity 15-30 mA). The conditioning stimuli were followed by reflex tests by 30-50 ms (conditioning A) and 80-100 ms (conditioning B). The latency and amplitude of the T-reflex and H-reflex were measured before (control) and after conditioning stimuli (A and B) and at sham (placebo). RESULTS: There were no significant differences between the right and left sides and between the control and placebo in both T-reflex and H-reflex. There were significant differences in both latency and amplitude of the T-reflex only between control and conditioning A. There were no significant differences between control and conditioning tests in the H-reflex. CONCLUSIONS: The above results suggest that supraspinal center and cutaneous fusimotor reflexes, which increase the sensitivity of the soleus muscle spindle, mediate the observed motoneuron excitability changes.     

Temporo-parietal junction stimulation in the treatment of depersonalization disorder

This is the first clinical trial of repetitive Transcranial Magnetic Stimulation (rTMS) in depersonalization disorder (DPD). After 3 weeks of right temporo-parietal junction (TPJ) rTMS, 6/12 patients responded. Five responders received 3 more weeks of right TPJ rTMS showing 68% DPD symptoms improvement. Right TPJ rTMS was safe and effective.     

The distribution of mechanosensory hair afferents within the locust central nervous system

The sensory projections from mechanosensory hairs on different body segments of the locust were filled with cobalt and their distribution within the central nervous system was described. A common feature of all projections was that in all ganglia axons were observed only in the median ventral tract and in the neuropil area known as the ventral association center. Within these restricted regions, axons from different segments or from different locations within a segment showed specific differences in the extent of their projection.     

The effect of glucocorticoid treatment on denervated rat hemidiaphragm

The degenerative process in phrenic nerve motor nerve terminals following nerve section was analyzed in rats that had previously been subjected to an intensive short term regimen of the steroid preparation triamcinolone. Morphological studies indicated that the onset time of degeneration was similar to that of untreated rats but less severe, and the time for maximal degenerative changes was increased. Concurrent to the preservation of motor nerve terminal structure under conditions of denervation, triamcinolone also induced myopathies in the diaphragm, the white muscle fibers being predominantly affected. Due to the structural aberrations of muscle, the indirect and direct twitch response of hemidiaphragms in triamcinolone treated rats we depressed. Data obtained from indirect post-tetanic potentiation (PTP) responses, however, did express the anatomical preservation of motor nerve terminals. These findings may add support to previous observations for the basis of effectiveness of the glucocorticoids in the treatment of neuromuscular disorders.