Principles and clinical methods of body surface gastric mapping: Technical review

BACKGROUND AND PURPOSE

Chronic gastric symptoms are common, however differentiating specific contributing mechanisms in individual patients remains challenging. Abnormal gastric motility is present in a significant subgroup, but reliable methods for assessing gastric motor function in clinical practice are lacking. Body surface gastric mapping (BSGM) is a new diagnostic aid, employs multi-electrode arrays to measure and map gastric myoelectrical activity non-invasively in high resolution. Clinical adoption of BSGM is currently expanding following studies demonstrating the ability to achieve specific patient subgrouping, and subsequent regulatory clearances. An international working group was formed in order to standardize clinical BSGM methods, encompassing a technical group developing BSGM methods and a clinical advisory group. The working group performed a technical literature review and synthesis focusing on the rationale, principles, methods, and clinical applications of BSGM, with secondary review by the clinical group. The principles and validation of BSGM were evaluated, including key advances achieved over legacy electrogastrography (EGG). Methods for BSGM were reviewed, including device design considerations, patient preparation, test conduct, and data processing steps. Recent advances in BSGM test metrics and reference intervals are discussed, including four novel metrics, being the 'principal gastric frequency', BMI-adjusted amplitude, Gastric Alimetry Rhythm Index™, and fed: fasted amplitude ratio. An additional essential element of BSGM has been the introduction of validated digital tools for standardized symptom profiling, performed simultaneously during testing. Specific phenotypes identifiable by BSGM and the associated symptom profiles were codified with reference to pathophysiology. Finally, knowledge gaps and priority areas for future BSGM research were also identified by the working group.

An insight into the functional alterations in the gut microbiome of healthy adults in response to a multi-strain probiotic intake: a single arm open label trial

Background

Probiotic supplements, by definition, provide a benefit to the host, but few studies have investigated the effect of probiotic supplements in healthy adult populations.

Purpose

The present, single arm, open label clinical trial, evaluated compositional and functional changes in the fecal microbiome of healthy adults after supplementation with a 14-strain probiotic.

Methods

We analysed the effect of a 14-strain probiotic blend (Bacillus subtilis NCIMB 30223, Bifidobacterium bifidum NCIMB 30179, B. breve NCIMB 30180, B. infantis NCIMB 30181, B. longum NCIMB 30182, Lactobacillus helveticus NCIMB 30184, L. delbrueckii subsp. bulgaricus NCIMB 30186, Lacticaseibacillus paracasei NCIMB 30185, Lactiplantibacillus plantarum NCIMB 30187, Lacticaseibacillus rhamnosus NCIMB 30188, L. helveticus NCIMB 30224, Lactobacillus salivarius NCIMB 30225, Lactococcus lactis subsp. lactis NCIMB 30222, and Streptococcus thermophilus NCIMB 30189), on the faecal microbiota of healthy young adults (n=41) in a single arm study. The adults consumed 4 capsules daily of the 14 strain blend(8 billion colony forming units/day) for 8 weeks. Compositional and functional changes in faecal microbiota before and after supplementation were assessed using shotgun metagenomic sequencing. Fasting breath analysis, faecal biochemistry and bowel habits were also assessed.

Results

In healthy adult participants, no significant changes to the overall alpha- or beta-diversity was observed after 8 weeks of multi-strain probiotic supplementation. However, in a simplified model that considered only time and individual differences, significant decreases (p < 0.05) in family Odoribacteraceae and Bacteroidaceae abundance and a significant increase (p < 0.05) in genus Megamonas abundance were observed. At a functional level, there were significant changes in functional gene abundance related to several functional pathways, including phenylalanine metabolism, O-antigen nucleotide sugar biosynthesis, bacterial chemotaxis, and flagellar assembly. No significant changes in stool form or frequency, fecal biochemistry, or methane and hydrogen breath tests were observed.

Conclusion

In healthy young adults, overall alpha- and beta-diversity did not change in response to probiotic intake even though modest compositional changes at the family and genus level were observed. However, at functional level, results identified changes in gene abundance for several functional pathways.

Randomised clinical trial: the use of alginates during preinvestigation proton pump inhibitor wash-out and their impact on compliance and symptom burden

BACKGROUND/AIMS

Investigation of gastro-oesophageal reflux disease is usually performed off proton pump inhibitors (PPIs). This can exacerbate symptoms, potentially impacting investigation accuracy if patients circumvent the preinvestigation instructions. There are no standard recommendations on how to manage PPI withdrawal. We aimed to assess the impact of structured alginate use on symptom burden.

METHODS

Participants were already established on ≥4 weeks of PPI therapy and being referred for manometry and 24-hour pH/impedance testing. Preinvestigation instructions involved stopping PPIs and H2 receptor antagonists for 1 week, but antacids and alginates were allowed until the night before. Participants were randomised to follow these standard instructions (control group), or the same instructions with the provision of Gaviscon Advance to be taken four times daily (treatment group). The primary outcome assessed change in Gastro-Oesophageal Reflux Disease Health-Related Quality of Life Score.

KEY RESULTS

Data for 48 patients were available for primary outcome assessment. While patients in the control group had a significant increase in symptoms (median difference 6.5, 95% CI (1 to 7), p=0.04), no change occurred in the treatment arm (median difference -1.5, 95% CI (-2, 3.5), p=0.54). There were no serious adverse events.

CONCLUSIONS

Structured alginate use prevents symptom exacerbation during preinvestigation PPI wash-out. These findings are limited to the 1-week wash-out period but can benefit thousands of patients undergoing investigation for gastro-oesophageal reflux each year. Further research is required to assess this effect in other settings, such as sustained PPI deprescription. The trial was funded by Reckitt Benckiser.

TRIAL REGISTRATION NUMBER

EudraCT registration 2019-004561-41.

Improving the Diagnostic Yield of High-Resolution Esophageal Manometry for GERD: The "Straight Leg-Raise" International Study

BACKGROUND & AIMS

The straight leg raise (SLR) maneuver during high-resolution manometry (HRM) can assess esophagogastric junction (EGJ) barrier function by measuring changes in intraesophageal pressure (IEP) when intra-abdominal pressure is increased. We aimed to determine whether increased esophageal pressure during SLR predicts pathologic esophageal acid exposure time (AET).

METHODS

Adult patients with persistent gastroesophageal reflux disease (GERD) symptoms undergoing HRM and pH-impedance or wireless pH study off proton pump inhibitor were prospectively studied between July 2021 and March 2022. After the HRM Chicago 4.0 protocol, patients were requested to elevate 1 leg at 45º for 5 seconds while supine. The SLR maneuver was considered effective when intra-abdominal pressure increased by 50%. IEPs were recorded 5 cm above the lower esophageal sphincter at baseline and during SLR. GERD was defined as AET greater than 6%.

RESULTS

The SLR was effective in 295 patients (81%), 115 (39%) of whom had an AET greater than 6%. Hiatal hernia (EGJ type 2 or 3) was seen in 135 (46%) patients. Compared with patients with an AET less than 6%, peak IEP during SLR was significantly higher in the GERD group (29.7 vs 13.9 mm Hg; P < .001). Using receiver operating characteristic analysis, an increase of 11 mm Hg of peak IEP from baseline during SLR was the optimal cut-off value to predict an AET greater than 6% (area under the receiver operating characteristic curve, 0.84; sensitivity, 79%; and specificity, 85%), regardless of the presence of hiatal hernia. On multivariable analysis, an IEP pressure increase during the SLR maneuver, EGJ contractile integral, EGJ subtype 2, and EGJ subtype 3, were found to be significant predictors of AET greater than 6% CONCLUSIONS: The SLR maneuver can predict abnormal an AET, thereby increasing the diagnostic value of HRM when GERD is suspected.

CLINICALTRIALS

gov ID: NCT04813029.

Fractional flow reserve derived from computed tomography coronary angiography in the assessment and management of stable chest pain: the FORECAST randomized trial

Aims 

Fractional flow reserve (FFR_CT) using computed tomography coronary angiography (CTCA) determines both the presence of coronary artery disease and vessel-specific ischaemia. We tested whether an evaluation strategy based on FFR_CT would improve economic and clinical outcomes compared with standard care.

Methods and results 

Overall, 1400 patients with stable chest pain in 11 centres were randomized to initial testing with CTCA with selective FFR_CT (experimental group) or standard clinical care pathways (standard group). The primary endpoint was total cardiac costs at 9 months. Secondary endpoints were angina status, quality of life, major adverse cardiac and cerebrovascular events, and use of invasive coronary angiography. Randomized groups were similar at baseline. Most patients had an initial CTCA: 439 (63%) in the standard group vs. 674 (96%) in the experimental group, 254 of whom (38%) underwent FFR_CT. Mean total cardiac costs were higher by £114 (+8%) in the experimental group, with a 95% confidence interval from −£112 (−8%) to +£337 (+23%), though the difference was not significant (P = 0.10). Major adverse cardiac and cerebrovascular events did not differ significantly (10.2% in the experimental group vs. 10.6% in the standard group) and angina and quality of life improved to a similar degree over follow-up in both randomized groups. Invasive angiography was reduced significantly in the experimental group (19% vs. 25%, P = 0.01).

Conclusion 

A strategy of CTCA with selective FFR_CT in patients with stable angina did not differ significantly from standard clinical care pathways in cost or clinical outcomes, but did reduce the use of invasive coronary angiography.

POS0365 ANTI-TNF GLUCOCORTICOID RECEPTOR MODULATOR ANTIBODY DRUG CONJUGATE FOR THE TREATMENT OF AUTOIMMUNE DISEASES

Background:

Glucocorticoids (GC) are potent drugs used for treating many inflammatory diseases. While GCs are effective in many immune diseases, dose and duration of administration is limited due to significant side effects. Resting immune cells have very little TNF expression on the cell surface and it is only in an activated state that TNF expression is upregulated. Upon immune cell stimulation, TNF is upregulated and although a significant amount of TNF is cleaved from an activated cell, a portion remains on the cell surface. We have observed that anti-TNF antibodies bind to transmembrane TNF (tmTNF) and undergo endocytosis to the lysosome (1). We have developed a stable antibody drug conjugate (ADC), ABBV-3373, that has a proprietary, highly potent, glucocorticoid receptor modulator (GRM) payload linked to an anti-TNF monoclonal antibody (mAb) that is able to deliver the GC payload to activated immune cells.

Objectives:

We hypothesized that a TNF ADC with a GRM payload would be able to deliver increased efficacy through both TNF inhibition and targeted GRM payload delivery to activated immune cells while sparing systemic glucocorticoid side effects.

Methods:

A mouse surrogate TNF GRM ADC was characterized in an acute in vivo contact hypersensitivity model of inflammation (CHS) and in a mouse model of collagen induced arthritis (mCIA). Additionally, the human anti-TNF GRM ADC, ABBV-3373 has been characterized in healthy volunteers.

Results:

In the CHS model the anti-TNF GRM ADC significantly inhibited the inflammatory response with minimal effect on systemic GC biomarkers. In mCIA a single dose of an anti-TNF GRM ADC, administered at disease onset, was able to completely inhibit arthritis for greater than 30 days while an anti-TNF mAb only partially inhibited disease. ABBV-3373, a human anti-TNF GRM ADC with a GC payload, was evaluated in a Phase 1 study in healthy volunteers. ABBV-3373 demonstrated antibody-like PK profile and ABBV-3373 did not impact cortisol levels at predicted efficacious doses while control subjects that received a single oral dose of 10 mg prednisone demonstrated expected decreases in cortisol levels.

Conclusion:

These data suggest that an anti-TNF ADC delivering a GRM payload into activated immune cells may provide improved efficacy in immune mediated diseases, while minimizing systemic side effects associated with standard GC treatment.

References:

[1]Deora, A. et al. MABs. 2017;9(4):680-695.

Disclosure of Interests:

Bob Stoffel Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Michael McPherson Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Axel Hernandez Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Christian Goess Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Suzanne Mathieu Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Wendy Waegell Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Shaughn Bryant Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Adrian Hobson Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Melanie Ruzek Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Yinuo Pang Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Hartmut Kupper Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Ronilda D’Cunha Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Julie Parmentier Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie, Timothy Radstake Shareholder of: AbbVie, Grant/research support from: AbbVie, Employee of: AbbVie

Endoscopic measurement of gastric pH associates with persistent acid reflux in patients treated with proton-pump inhibitors for gastroesophageal reflux disease

Background

Proton-pump inhibitors (PPIs) are the mainstay of gastroesophageal reflux disease (GERD) treatment, however, up to 30% of patients have a poor symptomatic response. PH-impedance is the gold standard to assess whether this is due to persistent acid reflux. We aimed to characterize clinical predictors of persistent esophageal acid reflux on PPIs including gastric pH measured during endoscopy.

Methods

We prospectively recruited patients with GERD and/or Barrett's esophagus (BE) on PPIs. All patients completed a symptom questionnaire (RDQ) and underwent gastroscopy with gastric pH analysis, immediately followed by ambulatory 24-hour pH-impedance. We used a modified cut-off of 1.3% for pathological esophageal acid exposure time (AET). Multiple linear regression model was used to analyze the correlation between AET and predictive variables.

Results

We recruited 122 patients, of which 92 (75.4%) were included in the final analysis [44 male (47.8%), median age 53 years (IQR: 43-66)]. Forty-four patients (47.8%) had persistent acid reflux with a median total AET of 2.2 (IQR1.2-5.0), as compared to 0.1 (IQR 0.0-0.2) in patients without persistent reflux (n=48; P<.001). There was no difference in age, gender, BMI, PPI-regimen, diagnosis of hiatus hernia or BE, and severity of symptoms between patients with normal and abnormal AET. Median gastric pH was significantly lower in patients with abnormal AET (5.8 vs 6.6, P=0.032) and it correlated with the total AET (P=.045; R2=12.0%). With a pH cut-off of 5.05, single point endoscopic gastric pH analysis had an area under the ROC curve (AUC) of 63.0% (95%CI 51.3-74.7) for prediction of pathological esophageal AET.

Conclusions

Symptoms and clinical characteristics are not useful to predict persistent acid reflux in patients on PPIs. One-point gastric pH correlates with 24-hour esophageal AET and could guide clinicians to assess response to PPIs, however, its utility needs validation in larger studies.

Audit and review for evidence-based red cell wastage reduction measures

Stocks of red blood cells (RBC) are held to ideally match supply and demand; hold too great a stock and unnecessary wastage occurs; too low a stock results in delay or lack of blood for the patient. Blood is a precious resource and its supply needs to be managed effectively. The aim was to identify how RBC units are wasted and propose laboratory-based reduction measures that would not compromise the clinical requirements of the patient. Wastage of RBC was investigated using a 'dashboard' query of a laboratory information management system. By employing service improvement tools, proposals were made to reduce unnecessary RBC waste while ensuring an adequate supply to the patient. The efficacy of those proposals was examined using the same dashboard to compare similar periods before and after their introduction. The reduction in RBC wastage for all groups during an eight month period (December to July) was from 6.4% (5.3% non-AB or B RhD-positive) pre-implementation to 4.4% (2.5% non-AB/B RhD-positive) post-implementation. Group O RhD-negative wastage reduced from 10.4% to 4.4% after introduction of waste-saving proposals. However, there was an increase in staff time required to introduce the changes and in associated Group and Screen testing (3.4 to 3.8 per unit issued). RBC wastage was significantly reduced (P<0.0001) by 32.8% (52%, non-AB/B RhD-positive), saving approximately 225 RBC units per annum. Financially, increased associated costs did not negate the savings made by the measures introduced.

Motilin: towards a new understanding of the gastrointestinal neuropharmacology and therapeutic use of motilin receptor agonists

The gastrointestinal hormone motilin has been known about for >40 years, but after identification of its receptor and subsequent development of new tools and methods, a reappraisal of its actions is required. Firstly, it is important to note that motilin and ghrelin receptors are members of the same family (similar genomic organization, gastrointestinal distribution and abilities to stimulate gastrointestinal motility), yet each fails to recognize the ligand of the other; and whereas ghrelin and ghrelin receptors are widespread outside the gastrointestinal tract, motilin and its receptors are largely restricted to the gastrointestinal tract. Secondly, although some studies suggest motilin has activity in rodents, most do not, and receptor pseudogenes exist in rodents. Thirdly, motilin preferentially operates by facilitating enteric cholinergic activity rather than directly contracting the muscle, despite the relatively high expression of receptor immunoreactivity in muscle. This activity is ligand-dependent, with short-lasting actions of motilin contrasting with longer-lasting actions of the non-selective and selective motilin receptor agonists erythromycin and GSK962040. Finally, the use of erythromycin (also an antibiotic drug) to treat patients requiring acceleration of gastric emptying has led to concerns over safety and potential exacerbation of antibiotic resistance. Replacement motilin receptor agonists derived from erythromycin (motilides) have been unsuccessful. New, non-motilide, small molecule receptor agonists, designed to minimize self-desensitization, are now entering clinical trials for treating patients undergoing enteral feeding or with diabetic gastroparesis. Thus, for the translational pharmacologist, the study of motilin illustrates the need to avoid overreliance on artificial systems, on structural information and on animal studies.

LINKED ARTICLES

This article is part of a themed section on Neuropeptides. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.170.issue-7.

Human visceral afferent recordings: preliminary report

BACKGROUND

Conditions characterised by chronic visceral pain represent a significant healthcare burden with limited treatment options. While animal models have provided insights into potential mechanisms of visceral nociception and identified candidate drug targets, these have not translated into successful treatments in humans.

OBJECTIVE

To develop an in vitro afferent nerve preparation using surgically excised freshly isolated human colon and vermiform appendix-mesentery tissues.

METHODS

Non-inflamed appendix (n=18) and colon (n=9) were collected from patients undergoing right and left hemicolectomy. Electrophysiological recordings were made from mesenteric nerves and the tissue stimulated chemically and mechanically.

RESULTS

Ongoing neuronal activity was sparse and where units occurred peak firing rates were: colon (2.0±0.4 spikes/s, n=4) and appendix (2.4±0.6 spikes/s, n=9). Afferent nerves innervating the appendix responded with a significant increase in activity following stimulation with inflammatory mediators (73±10.6 vs 3.0±0.3 spikes/s, n=6, p<0.001, inflammatory mediator vs baseline) and capsaicin (63±15.8 vs 2±0.3 spikes/s, n=3, p<0.001, capsaicin vs buffer). Afferent nerves innervating the colon responded with increased activity to blunt probing of the serosal surface.

CONCLUSIONS

This first-in-human study demonstrates afferent nerve recordings from human gut tissue ex vivo and shows that tissue may be stimulated both chemically and mechanically to study neuronal responses. Collectively, the results provide preliminary evidence to validate this in vitro human tissue model as one that may aid future disease mechanistic studies and candidate drug testing.

Review article: the psychoneuroimmunology of irritable bowel syndrome--an exploration of interactions between psychological, neurological and immunological observations

BACKGROUND

The pathogenesis of irritable bowel syndrome (IBS) is founded on interactive mechanisms. Disentangling these processes is a prerequisite for the development of effective drug therapy.

AIM

To identify the interaction between the various factors implicated in IBS.

METHODS

Articles pertaining to IBS pathogenesis focusing on psychoneuroimmunology were identified using following search terms: IBS, animal models, microbiota, probiotics, immunology, visceral hypersensitivity, imaging, psychology and visceral pain.

RESULTS

Cerebral imaging using MRI and proton emission tomography scanning has revealed differential regional cerebral activation, whereas stimuli induced activation has been captured by both MRI and cortical evoked potentials. At the peripheral neurological level, the concept of visceral hypersensitivity has been challenged as perhaps representing psychological traits with symptom over-reporting or hyper-vigilance. Gut mucosal immunology is thought to be relevant with immunological changes reflected as peripheral blood cytokine level changes. Molecular technology advances suggest a role for microbiota by activating the gut immunological system. These interactions have been examined in IBS animal models.

CONCLUSIONS

Translation of animal model findings to humans is needed to link the various psychological, neurological and immunological changes noted in IBS. This analysis may identify patient sub-groups, which will ultimately be critical for drug testing to be focused accordingly.

Review article: the psychoneuroimmunology of irritable bowel syndrome--an exploration of interactions between psychological, neurological and immunological observations

BACKGROUND

The pathogenesis of irritable bowel syndrome (IBS) is founded on interactive mechanisms. Disentangling these processes is a prerequisite for the development of effective drug therapy.

AIM

To identify the interaction between the various factors implicated in IBS.

METHODS

Articles pertaining to IBS pathogenesis focusing on psychoneuroimmunology were identified using following search terms: IBS, animal models, microbiota, probiotics, immunology, visceral hypersensitivity, imaging, psychology and visceral pain.

RESULTS

Cerebral imaging using MRI and proton emission tomography scanning has revealed differential regional cerebral activation, whereas stimuli induced activation has been captured by both MRI and cortical evoked potentials. At the peripheral neurological level, the concept of visceral hypersensitivity has been challenged as perhaps representing psychological traits with symptom over-reporting or hyper-vigilance. Gut mucosal immunology is thought to be relevant with immunological changes reflected as peripheral blood cytokine level changes. Molecular technology advances suggest a role for microbiota by activating the gut immunological system. These interactions have been examined in IBS animal models.

CONCLUSIONS

Translation of animal model findings to humans is needed to link the various psychological, neurological and immunological changes noted in IBS. This analysis may identify patient sub-groups, which will ultimately be critical for drug testing to be focused accordingly.

Evaluating oral stimulation as a treatment for dysphagia after stroke

Deglutitive aspiration is common after stroke and can have devastating consequences. While the application of oral sensory stimulation as a treatment for dysphagia remains controversial, data from our laboratory have suggested that it may increase corticobulbar excitability, which in previous work was correlated with swallowing recovery after stroke. Our study assessed the effects of oral stimulation at the faucial pillar on measures of swallowing and aspiration in patients with dysphagic stroke. Swallowing was assessed before and 60 min after 0.2-Hz electrical or sham stimulation in 16 stroke patients (12 male, mean age = 73 +/- 12 years). Swallowing measures included laryngeal closure (initiation and duration) and pharyngeal transit time, taken from digitally acquired videofluoroscopy. Aspiration severity was assessed using a validated penetration-aspiration scale. Preintervention, the initiation of laryngeal closure, was delayed in both groups, occurring 0.66 +/- 0.17 s after the bolus arrived at the hypopharynx. The larynx was closed for 0.79 +/- 0.07 s and pharyngeal transit time was 0.94 +/- 0.06 s. Baseline swallowing measures and aspiration severity were similar between groups (stimulation: 24.9 +/- 3.01; sham: 24.9 +/- 3.3, p = 0.2). Compared with baseline, no change was observed in the speed of laryngeal elevation, pharyngeal transit time, or aspiration severity within subjects or between groups for either active or sham stimulation. Our study found no evidence for functional change in swallow physiology after faucial pillar stimulation in dysphagic stroke. Therefore, with the parameters used in this study, oral stimulation does not offer an effective treatment for poststroke patients.

Assessing the temporal reproducibility of human esophageal motor-evoked potentials to transcranial magnetic stimulation

BACKGROUND

Although the electrophysiological properties and reproducibility of somatic limb motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) are well characterized, little is known about the reproducibility of MEPs for viscerosomatic structures such as the esophagus.

AIM

To determine the temporal reproducibility of esophageal MEPs to TMS.

METHODS

MEPs to TMS were recorded from the proximal esophagus, using a swallowed catheter housing a pair of electrodes, in eight healthy subjects at five stimulus intensities (SI) (motor threshold [MT] to 20% above MT). For each SI, 20 consecutive TMS stimuli at 5-second intervals were delivered over a single scalp site (dominant hemisphere at site exhibiting MT at lowest SI) and repeated 40 and 80 minutes thereafter. MEP amplitudes and latencies were measured, and means were sequentially calculated for each SI and then log-transformed. The repeatability coefficients (RC) for the three time points were calculated across each set of 20 stimuli and presented as an exponential ratio.

RESULTS

Best RC (amplitude/latency) were achieved at 120% SI relative to MT, being 1.8/1.2 (optimal = 1.0). For lower intensities of 115%, 110%, 105%, and 100% SI, the RC were 2.1/1.2, 2.1/1.1, 2.4/1.2, and 2.6/1.4, respectively. For all SI, the greatest reductions in RC occurred over the first 10 stimuli, with little additional gain beyond this number.

CONCLUSIONS

Latencies of esophageal MEP to TMS across intensities are highly reproducible, whereas amplitudes are more stimulus intensity-dependent, being most reliable and reproducible at the highest stimulus strengths.

SIGNIFICANCE

Using careful parameters, TMS can be used reliably in future studies of viscerosomatic structures, although the size of the response variability needs to be taken into account when assessing changes in cortico-fugal activity.

Mapping metabolic brain activation during human volitional swallowing: a positron emission tomography study using [18F]fluorodeoxyglucose

We have previously shown that labelled water positron emission tomography (H2(15)O PET) can be used to identify regional cerebral blood flow (rCBF) changes in the human brain during volitional swallowing. (18F) fluorodeoxyglucose (FDG PET), by comparison, uses a glucose analogue to quantitatively measure regional cerebral glucose metabolism (rCMRglc) rather than rCBF. The main advantage of FDG PET is improved spatial resolution, and because of its pharmacodynamic properties, activation can be performed external to the scanner, allowing subjects to assume more physiologic positions. We therefore conducted a study of the brain's metabolic response while swallowing in the erect seated position, using FDG PET. Eight healthy male volunteers were studied with a randomised 2 scan paradigm of rest or water swallowing at 20-second intervals for 30 minutes. Data were analysed with SPM99 using multisubject conditions and covariates design. During swallowing, analysis identified increased rCMRglc (P<0.01) in the following areas: left sensorimotor cortex, cerebellum, thalamus, precuneus, anterior insula, left and right lateral postcentral gyrus, and left and right occipital cortex. Decreased rCMRglc were also seen in the right premotor cortex, right and left sensory and motor association cortices, left posterior insula and left cerebellum. Thus, FDG PET can be applied to measure the brain metabolic activity associated with volitional swallowing and has the advantage of normal task engagement. This has implications for future activation studies in patients, especially those suffering swallowing problems after brain injury.

Induction of long-term plasticity in human swallowing motor cortex following repetitive cortical stimulation

OBJECTIVE

The excitability of corticobulbar projections to swallowing musculature undergoes remarkable long-term increases after short periods of pharyngeal stimulation. The aim of this study was to investigate the excitability of swallowing motor cortex following repetitive transcranial magnetic stimulation (rTMS).

METHODS

Twelve healthy subjects were given 100 rTMS pulses over motor cortex at frequencies of 1, 5 and 10 Hz at an intensity of 80% threshold for corticobulbar activation. The excitability of the corticobulbar projection was assessed before and after rTMS and compared both to sham stimulation and to the corticospinal projection.

RESULTS

Stimulation at 5 Hz, but not 1 Hz, 10 Hz or sham stimulation increased the excitability of the corticobulbar projection to the pharynx, reaching a peak 60 min after rTMS (Delta increase: 65%, P=0.016). Excitability in the projection from the opposite hemisphere also increased, suggesting the presence of inter-hemispheric interactions, whereas excitability in the projection to thenar muscles was unchanged.

CONCLUSIONS

Corticobulbar and corticospinal projections may differ in response to rTMS, implying differences in relative thresholds of inhibitory and excitatory elements in hand versus swallowing cortex.

SIGNIFICANCE

This might be a useful approach in the motor rehabilitation of dysphagic stroke patients who have damage to sensory projections to the swallowing cortex.

Changes in pharyngeal corticobulbar excitability and swallowing behavior after oral stimulation

Faucial pillar (FP) stimulation is commonly used in swallowing rehabilitation, yet its physiological basis remains uncertain. We investigated the effects of intraoral FP stimulation on human corticobulbar excitability and swallowing behavior, to explore the possibility of a central mechanism for functional change. In 10 healthy subjects, corticobulbar projections to pharynx were investigated with transcranial magnetic stimulation, via intraluminal electrodes, before and up to 1 h after 10 min of electrical FP stimulation with three frequencies (0.2, 1, and 5 Hz) or sham and peripheral (median nerve) stimulation. In a second study, swallowing behavior was assessed with videofluoroscopy before and after FP stimulation. FP stimulation at 5 Hz inhibited the corticobulbar projection (-14 +/- 6%, P < 0.02) and lengthened swallow response time (+114 +/- 24%, P = 0.02). By comparison, FP stimulation at 0.2 Hz facilitated this projection (+60 +/- 28%, P < 0.04), without enhancing swallowing behavior. Neither 1-Hz, sham, nor median nerve stimulation altered excitability. Thus changes in corticobulbar excitability to FP stimulation are frequency dependent with implications for the treatment for neurogenic swallowing dysfunction.

Differential changes in human pharyngoesophageal motor excitability induced by swallowing, pharyngeal stimulation, and anesthesia

We investigated the effects of water swallowing, pharyngeal stimulation, and oropharyngeal anesthesia on corticobulbar and craniobulbar projections to human swallowing musculature. Changes in pathway excitability were measured via electromyography from swallowed intraluminal pharyngeal and esophageal electrodes to motor cerebral and trigeminal nerve magnetic stimulation. After both water swallowing and pharyngeal stimulation, pharyngoesophageal corticobulbar excitability increased (swallowing: pharynx = 59 +/- 12%, P < 0.001; esophagus = 45 +/- 20%, P < 0.05; pharyngeal stimulation: pharynx = 76 +/- 19%, P < 0.001; esophagus = 45 +/- 23%, P = 0.05), being early with swallowing but late with stimulation. By comparison, craniobulbar excitability increased early after swallowing but remained unaffected by pharyngeal stimulation. After anesthesia, both corticobulbar (pharynx =-24 +/- 10%, P < 0.05; esophagus = -28 +/- 7%, P < 0.01) and craniobulbar excitability showed a late decrease. Thus swallowing induces transient early facilitation of corticobulbar and craniobulbar projections, whereas electrical stimulation promotes delayed facilitation mainly in cortex. With removal of input, both corticobulbar and craniobulbar projections show delayed inhibition, implying a reduction in motoneuron and/or cortical activity.

Driving plasticity in human adult motor cortex is associated with improved motor function after brain injury

Changes in somatosensory input can remodel human cortical motor organization, yet the input characteristics that promote reorganization and their functional significance have not been explored. Here we show with transcranial magnetic stimulation that sensory-driven reorganization of human motor cortex is highly dependent upon the frequency, intensity, and duration of stimulus applied. Those patterns of input associated with enhanced excitability (5 Hz, 75% maximal tolerated intensity for 10 min) induce stronger cortical activation to fMRI. When applied to acutely dysphagic stroke patients, swallowing corticobulbar excitability is increased mainly in the undamaged hemisphere, being strongly correlated with an improvement in swallowing function. Thus, input to the human adult brain can be programmed to promote beneficial changes in neuroplasticity and function after cerebral injury.

Comparative structural and functional analysis of photoreceptor neurons of Rho-/- mice reveal increased survival on C57BL/6J in comparison to 129Sv genetic background

To explore the possible influence of defined genetic backgrounds on photoreceptor viability and function in mice carrying a targeted disruption of the rhodopsin gene, the severities of retinopathies in Rho-/- mice on C57BL/6J and 129Sv congenic backgrounds were compared by light microscopy and electroretinography and qualitatively by in situ end labeling of DNA in apoptotic photoreceptor nuclei of retinal sections. Cone photoreceptor viability and function were shown to deteriorate more slowly on the C57BL/6J background in comparison to that of the 129Sv, with significantly greater numbers of outer nuclear layer nuclei in the retinas of C57BL/6J mice at 3 and 4 months of age. Both amplitude and waveform features of the ERG were shown to be remarkably different in the two strains, indicating an approximately 6-fold difference in C57BL/6J Rho-/- mice compared to 129Sv Rho-/- mice at 80 days. Thus, in comparison with the 129Sv strain, genetic modifiers appear to constitute a component of the C57BL/6J background, the expression of which significantly protects cone photoreceptors from apoptotic death in a mutation-induced murine retinopathy. The differences in phenotype revealed in this study are sufficient in principle to provide a basis for comparisons to be made between QTLs in light-induced and mutation-induced systems.

Comparison of cortical potentials evoked by mechanical and electrical stimulation of the rectum

Patients with irritable bowel syndrome have heightened perception of gut sensation. The mechanisms responsible for this remain unknown, due to current poor knowledge of the central processing of gut sensation. Cortical evoked potentials (CEPs) have been recorded following both electrical rectal stimulation (ERS) and mechanical rectal stimulation (MRS). Because of the lack of a direct comparison of these two methods, their robustness for future clinical use remains unknown. The aim of our study was to compare the characteristics of CEPs following ERS and MRS. CEPs were recorded from the vertex in 14 healthy volunteers following ERS with bipolar ring electrodes, and MRS by repeated rectal distension. CEPs were recorded in all subjects following electrical stimulation, but only in 11 subjects following mechanical stimulation. In comparison with electrical stimulation, mechanical stimulation produced CEPs with a smaller amplitude and longer latency. However, the morphology of CEPs following electrical and mechanical rectal stimulation was similar, with no difference in the interpeak latencies. In conclusion, we have demonstrated that electrical rectal stimulation is a more reliable stimulus for recording CEPs. The similarity of the morphology and interpeak latencies of the CEPs suggests that both stimuli are activating a similar network of cortical neurones.

Cortical processing of human somatic and visceral sensation

Somatic sensation can be localized precisely, whereas localization of visceral sensation is vague, possibly reflecting differences in the pattern of somatic and visceral input to the cerebral cortex. We used functional magnetic resonance imaging to study the cortical processing of sensation arising from the proximal (somatic) and distal (visceral) esophagus in six healthy male subjects. Esophageal stimulation was performed by phasic distension of a 2 cm balloon at 0.5 Hz. For each esophageal region, five separate 30 sec periods of nonpainful distension were alternated with five periods of similar duration without distension. Gradient echoplanar images depicting bold contrast were acquired using a 1.5 T GE scanner. Distension of the proximal esophagus was localized precisely to the upper chest and was represented in the trunk region of the left primary somatosensory cortex. In contrast, distension of the distal esophagus was perceived diffusely over the lower chest and was represented bilaterally at the junction of the primary and secondary somatosensory cortices. Different activation patterns were also observed in the anterior cingulate gyrus with the proximal esophagus being represented in the right midanterior cingulate cortex (BA 24) and the distal esophagus in the perigenual area (BA32). Differences in the activation of the dorsolateral prefrontal cortex and cerebellum were also observed for the two esophageal regions. These findings suggest that cortical specialization in the sensory-discriminative, affective, and cognitive areas of the cortex accounts for the perceptual differences observed between the two sensory modalities.

Laterality effects of human pudendal nerve stimulation on corticoanal pathways: evidence for functional asymmetry

BACKGROUND

Although motor and sensory pathways to the human external anal sphincter are bilateral, a unilateral pudendal neuropathy may still disrupt anal continence. Anal continence can, however, be preserved despite unilateral pudendal damage, and so to explain those differing observations, we postulated that pudendal innervation might be asymmetric.

AIMS

To explore the individual effects of right and left pudendal nerve stimulation on the corticofugal pathways to the human external anal sphincter and thus assess evidence for functional asymmetric pelvic innervation.

METHODS

In eight healthy subjects, anal sphincter electromyographic responses, evoked to transcranial magnetic stimulation of the motor cortex, were recorded 5-500 msec after digital transrectal electrical conditioning stimuli applied to each pudendal nerve.

RESULTS

Right or left pudendal nerve stimulation evoked anal responses of similar latencies but asymmetric amplitudes in six subjects: dominant responses (>50% contralateral side) from the right pudendal in four subjects and from the left in two. Cortical stimulation also evoked anal responses with amplitude 448 (121) microV and latency 20.9 (1.1) msec. When cortical stimulation was preceded by pudendal nerve stimulation, the cortical responses were facilitated at interstimulus intervals of 5-20 msec. Dominant pudendal nerve stimulation induced greater facilitation of the cortically evoked responses than the non-dominant nerve.

CONCLUSIONS

Cortical pathways to the external anal sphincter are facilitated by pudendal nerve conditioning, in an asymmetric manner. This functional asymmetry may explain the presence and absence of anal incontinence after unilateral pudendal nerve injury.

Viremia in neonatal herpes simplex virus infections

BACKGROUND

Polymerase chain reaction assays of the peripheral blood mononuclear cells (PBMC) and plasma may facilitate the diagnosis of neonatal herpes simplex virus (HSV).

METHODS

Assays for HSV DNA were submitted from at least 1 specimen site (PBMC, plasma or cerebrospinal fluid) in 11 consecutive cases of neonatal HSV infection.

RESULTS

HSV DNA was detected by PCR in the PBMC of 6 of 10 infants tested (60%), the plasma of 4 of 6 tested (67%) and the cerebrospinal fluid of 4 of 11 tested (36%).

CONCLUSIONS

HSV viremia is more frequent than previously appreciated, and detection of HSV DNA in PBMC and plasma is a useful diagnostic tool, particularly in infants without skin lesions.

Natal origins of migratory monarch butterflies at wintering colonies in Mexico: new isotopic evidence

Each year, millions of monarch butterflies from eastern North America migrate to overwinter in 10-13 discrete colonies located in the Oyamel forests of central Mexico. For decades efforts to track monarch migration have relied on observations and tag-recapture methods, culminating with the discovery of the wintering colonies in 1975. Monarch tag returns from Mexico, however, are few and primarily from two accessible colonies, and therefore tag-recapture techniques have not quantified natal origins or distinctiveness among monarch populations at wintering sites. Such information would be invaluable in the conservation of the monarch and its migration phenomenon since the wintering sites currently are threatened by habitat alteration. Here we show that stable hydrogen (deltaD) and carbon (delta13C) isotope ratios of wintering monarchs can be used to evaluate natal origins on the summer breeding range. Stable-hydrogen and carbon isotopic values of 597 wintering monarchs from 13 wintering roost sites were compared with isotopic patterns measured in individuals at natal sites across their breeding range over a single migration cycle. We determined that all monarch wintering colonies were composed of individuals originating mainly from the Midwest, United States, thereby providing evidence for a panmictic model of wintering colony composition. However, two colonies showed more northerly origins, suggesting possible priority colonies for conservation efforts.

Cortical localisation of magnetic fields evoked by oesophageal distension

Magnetoencephalographic source localisation techniques were used to measure oesophageal evoked magnetic fields from the cerebral cortex in 3 subjects. By using rapid balloon distension as a stimulus, a comparison of proximal and distal oesophageal cortical representation was made. The distal oesophagus was represented bilaterally in the insular cortex and SII as well as the inferior aspect of SI. The proximal oesophagus was represented unilaterally in superior and inferior SI, insular cortex and SII. Significantly, the superior portion of SI was consistently activated in subjects following stimulation of the proximal oesophagus, but similar activation was not found in response to distal stimulation. This may reflect the contribution from somatic afferent fibres in the striate muscle of the proximal segment. In conclusion, vagal afferents appear to contribute more to cortical activation following stimulation of the distal rather than the proximal oesophagus, while spinal afferents appear to be activated by both proximal and distal oesophageal stimulation.

Sensorimotor modulation of human cortical swallowing pathways

1. Transcranial magnetic stimulation over motor areas of cerebral cortex in man can activate short latency bilateral cortical projections to the pharynx and oesophagus. In the present paper we investigate the interaction between pathways from each hemisphere and explore how activity in these pathways is modulated by afferent feedback from the face, pharynx and oesophagus. 2. Comparison of unilateral and bilateral stimulation (using interstimulus intervals (ISIs) of 1, 5 or 10 ms between shocks) showed spatial summation of responses from each hemisphere at an ISI of 1 ms, indicating that cortical efferents project onto a shared population of target neurones. Such summation was not evident at ISIs of 5 or 10 ms. There was little evidence for transcallosal inhibition of responses from each hemisphere, as described for limb muscles. 3. Single stimuli applied to the vagus nerve in the neck or the supraorbital nerve, which alone produce intermediate (onset 20-30 ms) and long (50-70 ms) latency reflex responses in the pharynx and oesophagus, were used to condition the cortical responses. Compared with rest, responses evoked by cortical stimulation were facilitated when they were timed to coincide with the late part of the reflex. The onset latency was reduced during both parts of the reflex response. No facilitation was observed with subthreshold reflex stimuli. 4. Single electrical stimuli applied to the pharynx or oesophagus had no effect on the response to cortical stimulation. However, trains of stimuli at frequencies varying from 0.2 to 10 Hz decreased the latency of the cortically evoked responses without consistently influencing their amplitudes. The effect was site specific: pharyngeal stimulation shortened both pharyngeal and oesophageal response latencies, whereas oesophageal stimulation shortened only the oesophageal response latencies. 5. Cortical swallowing motor pathways from each hemisphere interact and their excitability is modulated in a site-specific manner by sensory input. The latter may produce a mixture of excitation and inhibition at both brainstem and cortical levels.

Spinal and pudendal nerve modulation of human corticoanal motor pathways

We investigated the effects of lumbosacral and pudendal nerve stimulation on the corticofugal pathways to the human external anal sphincter. In 11 healthy subjects, anal sphincter electromyographic responses, evoked to transcranial magnetic stimulation of the motor cortex, were recorded 5-500 ms after lumbosacral root or pudendal nerve stimulation. Lumbosacral and pudendal nerve stimulation alone evoked responses with amplitudes of 293 +/- 73 and 401 +/- 153 microV and latencies of 3.2 +/- 0.2 and 2.2 +/- 0.2 ms, respectively. Cortical stimulation also evoked responses with amplitudes of 351 +/- 104 microV and latencies of 20.9 +/- 1.1 ms. When lumbosacral or pudendal nerve stimulation preceded cortical stimulation, the cortically evoked responses were facilitated (P < 0.01), with the effect appearing greatest at 5-20 ms after both lumbosacral and pudendal excitation and at 50-100 ms after lumbosacral excitation alone. Our results demonstrate that cortical pathways to the external anal sphincter are facilitated by prior lumbosacral and pudendal nerve stimulation, indicating that sensorimotor interactions are important in the central neural control of sphincter function.

Cranial nerve modulation of human cortical swallowing motor pathways

Animal data indicate that cortical swallowing pathways can be modulated by cranial nerve afferent stimulation. We therefore studied the effects of human trigeminal and vagal nerve excitation on the corticofugal pathways to the oropharynx and esophagus, using electromagnetic stimulation. Unilateral stimulation of either the trigeminal or vagus nerve evoked two distinct reflex electromyographic responses in the pharynx and esophagus, an early response (latency range 19-30 ms) and a late response (latency range 42-72 ms). In the mylohyoid muscles, however, only a single response was seen (latency range 36-64 ms). Cortical stimulation also evoked electromyographic responses in the mylohyoid muscles, pharynx, and esophagus, with latencies of 8.5 +/- 0.3, 9.3 +/- 0.3, and 10.1 +/- 0.4 ms, respectively. When either trigeminal or vagus nerve stimulation preceded cortical stimulation, the cortically evoked responses were facilitated, with maximal effects at interstimulation intervals of 30-200 ms for pharynx and esophagus (P < 0.02) and at interstimulation intervals of 50-100 ms for mylohyoid muscles (P < 0.05). Our results demonstrate that stimulation of human cranial nerve afferent fibers facilitates cortical swallowing motor pathways.

Evaluation of a quantitative competitive PCR assay for measuring herpes simplex virus DNA content in genital tract secretions

Previous studies have shown an association between the approximate titer of herpes simplex virus (HSV) DNA in clinical specimens and the ability to isolate HSV from genital secretions. To control for variance in amplification conditions, we developed a competitive quantitative PCR (QC PCR) for the detection of HSV DNA. The assay accurately measured from 10 to 10(6) copies of HSV DNA. We compared the QC PCR with our previous semiquantitative detection method and found concordance for 61 of 63 positive specimens. We also evaluated the HSV DNA content from individual swabs of genital secretions obtained from individual sites of the genital tract (cervix, vulva, and rectum) with that from one swab with secretions from all three sites. The concordance for detecting HSV DNA was 91%; for only 4 of 143 collection days was there a > 1 log difference between the two collection methods. A single swab with secretions from all three genital sites and evaluated in a QC PCR format can accurately measure the frequency of subclinical and clinical shedding of HSV and the titer of HSV shed from the genital region. Such an approach should be very useful in the evaluation of antiviral chemotherapy for HSV.

Frequent genital herpes simplex virus 2 shedding in immunocompetent women. Effect of acyclovir treatment

Reactivation of herpes simplex virus type 2 (HSV-2) occurs intermittently as perceived clinically and by viral culture. We performed a series of studies to evaluate the frequency and pattern of HSV-2 reactivation using both viral isolation and HSV PCR assay. Daily samples of genital secretions were obtained from 27 HSV-2 seropositive women; a subset of subjects obtained samples while receiving oral acyclovir 400 mg PO twice a day. HSV DNA was detected in genital swab specimens on 28% of 1,410 d compared with 8.1% of days by viral isolation. 11 of 20 women had HSV DNA detected on > 20% of days, 4 on > 50%, and 2 on > 75% of days; in contrast, none of the women shed on > 21% of days by viral isolation. The daily administration of oral acyclovir promptly reduced the frequency of HSV DNA detection by a median of 80%. Within 3-4 d of discontinuing daily acyclovir, HSV DNA again appeared in the genital area. HSV-2 shedding in the genital mucosa occurs much more frequently than previously appreciated. This frequent reactivation likely plays a role in the epidemic spread of genital herpes worldwide.

Manometric asymmetry in the anal canal in controls and patients with fecal incontinence

PURPOSE

This study was designed to ascertain the existence of manometric asymmetry in the anal canal in controls and in patients with fecal incontinence.

METHODS

A computerized manometric technique with an eight-channel perfusion catheter was used. Coefficient of variation (CV, a mathematical expression of the degree or magnitude of deviation of a set of data points from the mean) was developed in this study as an index of anal canal manometric asymmetry.

RESULTS

At 1 cm from the anal verge, mean CV was 9.3 and 8.7 percent in asymptomatic control males and females, respectively. During a maximum voluntary squeeze effort, mean CV in control males was 9.3 percent and was not significantly different (P = 0.28) from that in control females (7.8 percent). In 14 consecutive female patients with fecal incontinence, mean CV at rest (1 cm from the anal verge) was 21 percent and was significantly higher (P < 0.01) than in control females. Similarly, during a maximum voluntary squeeze effort, mean CV in patients with fecal incontinence was 20.5 percent and was significantly higher (P < 0.01) than in the female control group (7.8 percent).

CONCLUSION

It is concluded that CV, a method of expressing anal sphincter manometric asymmetry, is a useful manometric parameter in the assessment of anorectal function.

Topographic mapping of cortical potentials evoked by distension of the human proximal and distal oesophagus

We describe cortical potentials evoked by balloon distension of the proximal and distal oesophagus in 8 healthy right handed volunteers. Oesophageal stimulation was performed using a pump which rapidly inflated a 2 cm silicone balloon positioned either 3 cm distal to the upper oesophageal sphincter or 5 cm proximal to the lower oesophageal sphincter, at a frequency of 0.2 Hz, using inflation volumes which produced a definite but not painful sensation. Oesophageal evoked cortical potentials were recorded in all subjects with an initial negative and positive component (N1 and P1), followed by a second negative and positive component (N2 and P2) in 6 subjects. The morphology and the scalp topography of the N1 component elicited by proximal and distal oesophageal stimulation suggests activation of the primary somatosensory cortex and/or the insular. There was also evidence for hemispheric dominance for the N1 potential which was independent of handedness. The frontal emphasis of the proximal oesophageal N1 component, in contrast to the central emphasis of the distal oesophageal N1 component, suggests that different neuronal populations were activated by stimulation of the two sites. The frontal emphasis of the ensuing P1 component from both oesophageal sites suggests that it originates in a separate precentral source. The topography of the N2 components obtained by stimulation of either oesophageal site was similar to that of the N1 component, suggesting that they originate in similar areas of the cortex. The P2 component evoked by stimulation of both oesophageal sites was localised at the vertex. The inter- and intra-subject variation in the morphology of the N2 and P2 components suggests that secondary cortical processes related to cognition may be involved in their generation.

A systems approach to gathering and analyzing patient and family complaints and suggestions

Most medical facilities' leaders are concerned with satisfying the patients who use their healthcare organization. Whereas many facilities have identified specific individuals whose job it is to hear patient complaints, the authors promote the view that all staff members play important roles in patient advocacy. Management's role is to determine how to collect and analyze the complaints and suggestions voiced by patients throughout their healthcare experience. This article presents one method.

Esophageal myoelectric responses to magnetic stimulation of the human cortex and the extracranial vagus nerve

We describe the use of magnetic stimulation of the human motor cortex and the extracranial vagus nerve in the neck to study human esophageal electromyographic (EMG) responses. Diffuse cortical stimulation produced both an early and a late EMG response in the proximal esophagus with latencies of 10.9 +/- 0.5 and 43.4 +/- 4.3 ms, respectively. Increasing the stimulation intensity increased the amplitude and duration, but reduced the latency, of the early response (P < 0.01), whereas the late response remained unchanged. The early response, but not the late response, was facilitated when cortical stimulation was performed during valsalva maneuver. Maximal early response amplitudes were obtained by focal stimulation of either hemisphere 4-8 cm lateral to the vertex. Stimulation of the neck over the extracranial vagus nerve at the angle of the jaw also produced an early and a late EMG response in the proximal esophagus with latencies of 4.3 +/- 0.4 and 56.8 +/- 14.5 ms, respectively. Early responses were also recorded in the midesophagus and distal esophagus from either cortical or vagal stimulation, but amplitudes were smaller and rise times were longer, suggesting passive "volume conduction" from the proximal esophagus. Comparison of laryngeal, pharyngeal, and esophageal early EMG responses showed similar amplitudes and rise times, suggesting that the action potentials were generated locally at each site and that true esophageal responses were being detected.

Downregulation of cGMP phosphodiesterase induced by expression of GTPase-deficient cone transducin in mouse rod photoreceptors

PURPOSE

Photoexcitation of vertebrate retinal rod photoreceptors stimulates GTP binding to the transducin alpha subunit. Like other GTP-binding proteins, transducin restores itself to an inactive form by hydrolyzing its bound GTP. The role of GTP hydrolysis in phototransduction was investigated.

METHODS

A mutant form of cone transducin alpha deficient in its ability to hydrolyze bound GTP was expressed in mouse rod photoreceptors.

RESULTS

Expression of the mutant cone transducin alpha at levels threefold to sixfold higher than endogenous rod transducin alpha led to a specific depletion of the transducin target, cGMP phosphodiesterase, and a decrease in the cGMP level. Suction electrode recordings revealed abnormally prolonged flash responses, decreased maximal response amplitudes, and a shift in the stimulus-response relation to higher flash strengths.

CONCLUSIONS

Rods expressing high levels of GTPase-deficient cone transduction alpha have reduced levels of phosphodiesterase catalytic subunits and cGMP. These changes are associated with prolonged flash responses, reduced dark current, and decreased sensitivity to light.

Patients with dementia involving families to maximize nursing care

Incorporating family members in the care of patients with dementia provided pertinent psychosocial data, led to mutual decision-making regarding care, and produced changes in the responses of the residents with dementia, as well as in the family and nursing staff. The experimental group experienced increases in psychosocial nursing diagnoses with planning and interventions to meet the problems, more extensive problem description, and an active focus on interaction and change in the nurse's notes. As a result of collaborative nursing and family involvement, personal articles were brought from home; family collateral visits and interaction increased; families were more involved in the unit, medical center, and support groups; and p.r.n. medication use was decreased. As health-care technology prolongs the life of patients with chronic illness and sequelae such as dementia, nurses will need to continue to include families as collaborators in providing quality care.