Transpelvic Magnetic Stimulation Enhances Penile Microvascular Perfusion in a Rat Model: A Novel Interventional Strategy to Prevent Penile Fibrosis after Cavernosal Nerve Injury

PURPOSE

Penile microvascular dysfunction is a known contributor to erectile dysfunction (ED) and penile fibrosis has been shown to impair microvascular perfusion (MVP). Our objectives were to: (i) determine beneficial effects of TPMS to modulate penile MVP, (ii) determine its mechanism, (iii) evaluate impact of cavernosal nerve injury (CNI) on penile MVP, and (iv) determine time-course of cavernosal tissue elastin changes after CNI in rats.

MATERIALS AND METHODS

Adult male rats (n=5) were anesthetized and subjected to TPMS (13%, 15%, and 17%) and MVP changes were recorded using laser speckle contrast imaging (LSCI). Another group of male rats were subjected to either bilateral cavernosal nerve injury (CNI; n=7) or sham surgery (n=7). After recovery, animals were monitored for MVP using LSCI before and after TPMS. Rat penile tissues were harvested and analyzed for fibrosis using a marker for elastin.

RESULTS

Rat TPMS resulted in a stimulus dependent increase in MVP; maximal perfusion was observed at 17%. L-N(G)-Nitroarginine methyl ester (L-NAME) resulted in a marked decrease in TPMS induced MVP increase (393.33 AU vs. 210.67 AU). CNI resulted in 40% to 50% decrease in MVP. CNI produced a remarkable increase in elastin deposits that are noticeable throughout the cavernosal tissues post injury.

CONCLUSIONS

TPMS is a novel and non-invasive intervention to improve penile MVP after CNI. Potential application includes treatment of ED and sexual function preservation following cancer treatment, possibly through improved penile hemodynamics that might help prevent penile hypoxia and fibrosis.

Preclinical applications of high-definition manometry system to investigate pelvic floor muscle contribution to continence mechanisms in a rabbit model

External anal sphincter (EAS), external urethral sphincters, and puborectalis muscle (PRM) have important roles in the genesis of anal and urethral closure pressures. In the present study, we defined the contribution of these muscles alone and in combination with the sphincter closure function using a rabbit model and a high-definition manometry (HDM) system. A total of 12 female rabbits were anesthetized and prepared to measure anal, urethral, and vaginal canal pressures using a HDM system. Pressure was recorded at rest and during electrical stimulation of the EAS and PRM. A few rabbits (n = 6) were subjected to EAS injury and the impact of EAS injury on the closure pressure profile was also evaluated. Anal, urethral, and vaginal canal pressures recorded at rest and during electrical stimulation of EAS and PRM demonstrated distinct pressure profiles. EAS stimulation induced anal canal pressure increase, whereas PRM stimulation increased the pressures in all the three orifices. Electrical stimulation of EAS after injury resulted in about 19% decrease in anal canal pressure. Simultaneous electrical stimulation of EAS and PRM resulted in an insignificant increase of individual anal canal pressures when compared with pressures recorded after EAS or PRM stimulations alone. Our data confirm that HDM is a viable system to measure dynamic pressure changes within the three orifices and to define the role of each muscle in the development of closure pressures within these orifices in preclinical studies.NEW & NOTEWORTHY We anticipate that with this new HDM technology, physiological changes within these orifices may be redefined using the extensive data that are generated from 96 sensors. When compared with conventional methods, HDM offers the advantages of an increased response rate, as well as the utilization of 96 circumferential sensors to simultaneously measure pressure along the three orifices. Our findings suggest a potential use of this technology to better define urinary leak point pressure.

AB0018 ACCUMULATION OF FUNCTIONALLY MATURE CD1C+ DENDRITIC CELLS CONTRIBUTES TO SYNOVIAL INFLAMMATION IN INFLAMMATORY ARTHRITIS

Background:

Myeloid Dendritic Cells (DC) are potent antigen presenting cells that can be subdivided into CD141 and CD1c+ DC. We have previously reported an unacknowledged role for CD141+DC in the IA synovium. However, the identification and function of CD1c+ DC in the IA synovium has yet to be fully elucidated.

Objectives:

To investigate if CD1c+DC reside in the IA synovium and ascertain if they represent a unique population, distinct from peripheral CD1c+DC and if they contribute to synovial inflammation.

Methods:

Synovial tissue (ST) biopsies and synovial fluid mononuclear cells (SFMC) were obtained via arthroscopy and healthy control (HC) ST was obtained during ACL surgery. Synovial tissue single cells suspensions were generated following enzymatic and mechanical digestion. Single cell analysis of synovial tissue cell suspensions, along with PBMC and SFMC was performed by multicolour flow cytometry. CD1c+DC were sorted from IA synovial fluid and peripheral blood and bulk RNA sequencing was performed. CD1c+DC functionality and maturation was assessed using OVA DQ phagocytosis assays, multiplex ELISA and DC: T cell cocultures.

Results:

Within the circulation the frequency of CD1c+DC are significantly decreased in IA peripheral blood compared to HC (p<0.01) in addition to expressing significantly higher levels of the maturation markers CD80 (p<0.01) and CD40 (p=0.08). IA peripheral blood DC also express significantly higher levels of CXCR3 (p<0.01) and CCR7 (p<0.05) compared to HC - suggestive of DC migration from the periphery to the synovium. Following RNA-seq analysis, IPA and differentially expressed gene (DEG) analysis revealed an enrichment in genes involved in DC maturation, TLR signalling and chemokine signalling in IA peripheral blood compared to HC. In support of the hypothesis that DC migrate and accumulate in the IA synovium, CD1c+ DC were identified in IA ST and were significantly enriched compared to IA peripheral blood (p<0.01). IA ST CD1c+DC express significantly higher levels of the activation marker CD80 compared to IA peripheral blood (p<0.05) or HC ST (p<0.05). Upon examination of IA synovial fluid, we report similar findings to ST, whereby CD1c+DC are enriched in synovial fluid compared to PB (p<0.001). Moreover, RNA sequencing and PCA analysis of synovial versus blood CD1c+DC revealed distinct transcriptional variation between both sites. Functionally, synovial CD1c+DC express higher levels of the maturation markers CD80, CD83, CD40, PD-L1 and BTLA (all p<0.05) and have distinct coexpression of these maturation markers which is unique to the synovium. Synovial CD1c+DC are less phagocytic compared to peripheral blood DC, have decreased production of MMP1 and MMP9 and importantly are still capable of additional activation in-vitro. Finally, synovial CD1c+DC induce the proinflammatory cytokines TNFα, GMCSF, IL-17a and IFNγ from CD4+ T-cells in allogeneic DC: T cells cocultures.

Conclusion:

Mature circulatory CD1c+DC migrate and accumulate in the IA synovium. Synovial DC are present in the IA synovium in a mature state, have distinct tissue specific characteristics and can induce proinflammatory CD4+T cell responses.

Acknowledgements:

We would like to thank all the patients who contributed to this study

Disclosure of Interests:

Mary Canavan: None declared, Viviana Marzaioli: None declared, Vipul Bhargava Employee of: Janssen Research and Development, Sunil Nagpal Employee of: Janssen Research and Development, Phil Gallagher: None declared, Conor Hurson: None declared, Ronan Mullan: None declared, Douglas Veale Speakers bureau: Abbvie, Janssen, Novartis, Pfizer, MSD, UCB, Consultant of: Abbvie, Janssen, Novartis, Pfizer, MSD, UCB, Grant/research support from: Pfizer, Janssen, AbbVie, UCB, Ursula Fearon Speakers bureau: Abbvie, Grant/research support from: Pfizer, Janssen, Abbvie, UCB

Rheumatoid arthritis synovial microenvironment induces metabolic and functional adaptations in dendritic cells

Rheumatoid arthritis (RA) is a chronic autoimmune disease which causes degradation of cartilage and bone. It is well appreciated that the pathogenic hallmark of RA is the mass influx of inflammatory cells into the joint. However, the role that dendritic cells (DC) may play in this inflammatory milieu is still relatively unexplored. Moreover, the contribution this unique synovial microenvironment has on DC maturation is still unknown. Using monocyte-derived DC (MoDC), we established an in-vitro model to recapitulate the synovial microenvironment to explore DC maturation. MoDC treated with conditioned media from ex-vivo synovial tissue biopsy cultures [explant-conditioned media (ECM)] have increased expression of proinflammatory cytokines, chemokines and adhesion molecules. ECM DC have increased expression of CD83 and CC-chemokine receptor (CCR)7 and decreased expression of CCR5 and phagocytic capacity, suggestive of heightened DC maturation. ECM-induced maturation is concomitant with altered cellular bioenergetics, whereby increased expression of glycolytic genes and increased glucose uptake are observed in ECM DC. Collectively, this results in a metabolic shift in DC metabolism in favour of glycolysis. These adaptations are in-part mediated via signal transducer and activator of transcription-3 (STAT-3), as demonstrated by decreased expression of proinflammatory cytokines and glycolytic genes in ECM DC in response to STAT-3 inhibition. Finally, to translate these data to a more in-vivo clinically relevant setting, RNA-seq was performed on RA synovial fluid and peripheral blood. We identified enhanced expression of a number of glycolytic genes in synovial CD1c+ DC compared to CD1c+ DC in circulation. Collectively, our data suggest that the synovial microenvironment in RA contributes to DC maturation and metabolic reprogramming.

Evaluation of Age- and Radical-Prostatectomy Related Changes in Male Pelvic Floor Anatomy Based on Magnetic Resonance Imaging and 3-Dimensional Reconstruction

Purpose

Puborectalis muscles (PRM) and ischiocavernosus muscles (ICM) play important roles in urinary continence and male erectile functions. Understanding of anatomy and surgical-injury related changes to these muscles is critical to monitor changes in continence or erectile function. Anatomical description of these muscles has undergone revisions because these conclusions were derived from cadavers. Our objectives were to: (i) elucidate male pelvic muscles by in-vivo magnetic resonance imaging (MRI) and 3-dimensional (3-D) reconstruction of these images and (ii) compare PRM and ICM thickness in healthy volunteers and symptomatic patients.

Materials and Methods

Healthy young male (mean age, 25 years; n=5), older male (age, 65–70 years; n=5), and post-prostatectomy patients with erectile dysfunction and urinary incontinence (age, 65–70 years; n=5) were scanned on a 3T-magnetic resonance scanner. Images were acquired from slices above urinary bladder base to urethra entry into penis. Pelvic bone, bladder/urethra, corpus cavernosum, ICM, PRM, and prostate were segmented. 3-D models of each structure were generated and assembled into composite images, and ICM and PRM thicknesses were calculated.

Results

We successfully reconstructed 3-D male pelvic floor anatomy including ICM, PRM, bladder, urethra, bulbospongiosus, corpus cavernosa, prostate and bones from the two groups. We documented significant reduction in PRM and ICM thickness in older men.

Conclusions

This is perhaps the first 3-D reconstruction of male pelvic floor structures based on in-vivo MRI in healthy and symptomatic patients. Observed reduction in PRM and ICM thickness is possibly due to age-related atrophy.

Characterization of urethral fibrosis in a rabbit model: Potential roles of Wnt-β catenin pathway and epithelial to mesenchymal transition

AIM

To elucidate the precise cellular and molecular mechanisms that underlie urethral fibrogenesis.

METHODS

Endoluminal electrocautery injury (using Karl Storz 10 Fr. Pediatric urethroscope) was employed in male rabbits (n = 6) to create mucosal injury. Retrograde urethrogram (RUG) and endoluminal ultrasound techniques were used to assess severity and changes in luminal cross-sectional area. Six control rabbits were subjected to sham injury, in which the electrocautery was inserted but not powered. Urethral tissues were harvested 30 days postinjury and subjected to RNA sequencing and quantitative polymerase chain reaction (qPCR) to determine changes in gene expression. Histological, immunostaining, and Western blot studies were used to determine changes in protein expression of known markers of fibrosis (eg, collagen, Integrinαv, GIV/Girdin, transforming growth factor-β (TGF-β), and pSMAD1,2,3).

RESULTS

Trichrome staining confirmed increased connective tissue in urethral scar tissues. Immunostaining revealed a potential role for epithelial to mesenchymal cell transition (EMT) and positive labeling for all fibrotic markers (eg, collagen-1, Integrin αv, GIV/Girdin, transforming growth factor-β (TGF-β), and SMAD1,2,3). Western blot analysis confirmed increased protein levels of these fibrotic markers.

CONCLUSION

Our RNA sequencing and qPCR studies, in conjunction with our protein data, suggest that urethral mucosal fibrogenesis may be mediated by novel fibrogenic signaling pathways involving Wnt-β catenin, TGF-β, GIV/Girdin, and EMT which lead to increased collagen deposition. Therapeutic strategies targeting these pathways may be beneficial in attenuating fibrogenesis and stricture progression.

A prospective genome-wide study of prostate cancer metastases reveals association of wnt pathway activation and increased cell cycle proliferation with primary resistance to abiraterone acetate-prednisone

Background

Genomic aberrations have been identified in metastatic castration-resistant prostate cancer (mCRPC), but molecular predictors of resistance to abiraterone acetate/prednisone (AA/P) treatment are not known.

Patients and methods

In a prospective clinical trial, mCRPC patients underwent whole-exome sequencing (n = 82) and RNA sequencing (n = 75) of metastatic biopsies before initiating AA/P with the objective of identifying genomic alterations associated with resistance to AA/P. Primary resistance was determined at 12 weeks of treatment using criteria for progression that included serum prostate-specific antigen measurement, bone and computerized tomography imaging and symptom assessments. Acquired resistance was determined using the end point of time to treatment change (TTTC), defined as time from enrollment until change in treatment from progressive disease. Associations of genomic and transcriptomic alterations with primary resistance were determined using logistic regression, Fisher's exact test, single and multivariate analyses. Cox regression models were utilized for determining association of genomic and transcriptomic alterations with TTTC.

Results

At 12 weeks, 32 patients in the cohort had progressed (nonresponders). Median study follow-up was 32.1 months by which time 58 patients had switched treatments due to progression. Median TTTC was 10.1 months (interquartile range: 4.4-24.1). Genes in the Wnt/β-catenin pathway were more frequently mutated and negative regulators of Wnt/β-catenin signaling were more frequently deleted or displayed reduced mRNA expression in nonresponders. Additionally, mRNA expression of cell cycle regulatory genes was increased in nonresponders. In multivariate models, increased cell cycle proliferation scores (≥ 50) were associated with shorter TTTC (hazard ratio = 2.11, 95% confidence interval: 1.17-3.80; P = 0.01).

Conclusions

Wnt/β-catenin pathway activation and increased cell cycle progression scores can serve as molecular markers for predicting resistance to AA/P therapy.

Pulmonary Calcifications: Is it an Entity in the New World Dialysis Patient?

Metastatic pulmonary calcification (MPC) has been described in the literature to affect up to 60% of dialysis patients. Several case series of MPC were described in 1960s and 1970s. Patients are generally asymptomatic or may present with acute respiratory distress. This entity is associated with up to 60% mortality. We hereby report a case of chronic kidney disease on maintenance hemodialysis who presented with unexplained recurrent dyspnea despite adequate hemodialysis. She was evaluated and found to have a rare presentation of calciphylaxis.

Age and multiparity related urethral sphincter muscle dysfunction in a rabbit model: Potential roles of TGF-β and Wnt-β catenin signaling pathways

AIMS

Prior studies demonstrate increased incidence of urinary incontinence (UI) in the geriatric population which affects their quality of life. Pathophysiology of UI in the geriatric population and the underlying molecular mechanisms are still unclear. To elucidate these mechanisms, we performed a pre-clinical study in a rabbit model and the objectives were to (i) determine the effect of aging as well as multiparity on urethral sphincter muscle thickness and urethral closing pressure (UCP); (ii) examine the role of fibrosis and atrophy; and (iii) elucidate the molecular pathways that mediate fibrosis and atrophy in the urethral tissue.

METHODS

New Zealand White female rabbits (n = 6 each; young 6-12 months and old over 30 months of age) were anesthetized and urethral muscle thickness and sphincter closure function were measured. Rabbits were then sacrificed and urethral tissues (bladder neck and mid-urethra) were collected to process for immunostaining as well as for molecular studies for markers for fibrosis (β-catenin which is an important mediator of Wnt signaling, Collagen-1, and TGF-β) and atrophy (MuRF-1).

RESULTS

Our studies showed a significant decrease in the urethral sphincter muscle thickness and closure function with age. Age-related increase in protein and mRNA expression levels of fibrosis, as well as atrophy markers were observed in the bladder neck and mid-urethral tissues.

CONCLUSIONS

Age and multiparity related increase in fibrosis and atrophy of urethral sphincter muscles may contribute to impaired urethral closure function seen in old animals.

Exploration of male urethral sphincter complex using diffusion tensor imaging (DTI)-based fiber-tracking

BACKGROUND

Urinary incontinence is a major clinical problem arising primarily from age-related degenerative changes to the sphincter muscles. However, the precise anatomy of the normal male sphincter muscles has yet to be established. Diffusion tensor imaging (DTI) may offer a unique insight into muscle microstructure and fiber architecture.

PURPOSE

To explore the anatomy of the urethral sphincter muscles pertinent to urinary continence function using DT-MRI.

STUDY TYPE

Prospective cohort study.

SUBJECTS

Eleven normal male subjects (mean age: 25.4 years); two subjects were scanned in three separate sessions to assess reproducibility.

FIELD STRENGTH/SEQUENCE

3T; using a diffusion-weighted spin echo planar sequence.

ASSESSMENT

DT parameters including fractional anisotropy (FA), primary (λ1 ), secondary (λ2 ), and tertiary (λ3 ) eigenvalues, Apparent diffusion coefficient and radial diffusivity were analyzed statistically, while tracked muscle fibers were assessed visually.

STATISTICAL TESTS

Regional differences (sphincters and longitudinal muscle of the urethra) in the DTI indices were assessed by one-way analysis of variance. A Tukey post-hoc test was used to identify significant differences between muscle regions.

RESULTS

Two sphincter muscles, one proximal near the base of the bladder, corresponding to the lisso-sphincter, and the other distal to the end of the prostate corresponding to the rhabdo-sphincter, surrounding a central urethral muscle fiber bundle, were clearly identified. FA was higher and λ3 lower in the proximal sphincter muscle compared to the central urethral muscle and the distal sphincter (P < 0.05). The average coefficient of variation ranged from 5-12% for the DTI indices.

DATA CONCLUSION

Since DTI values are known to reflect underlying tissue microarchitecture, significant differences in DTI indices identified here between the muscles of the urethral complex may potentially arise from differences in tissue microarchitecture that may in turn be related to the specific function of the sphincter and other muscles.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1002-1011.

A Novel Endoluminal Ultrasound Imaging Technique to Determine Urethral Luminal Cross-Sectional Area

INTRODUCTION AND OBJECTIVES

Retrograde urethrogram (RUG) and voiding cystourethrogram (VCUG) are currently the gold standard imaging technique for diagnosis of urethral stricture and determination of stricture location. However, RUG and VCUG have multiple limitations. These techniques require exposure to ionizing radiation, the quality is operator and patient dependent, there is a moderate degree of invasiveness with urethral catheterization, can have artifacts because of patient positioning that underestimates stricture length. The development of novel imaging modalities without ionizing radiation to accurately evaluate the presence, location, length, and lumen cross-sectional area (CSA) of the urethral stricture would be of great value. The objective of this study was to develop a novel endoluminal ultrasound (ELUS) imaging technique that permits the accurate quantitation of urethral stricture.

METHODS

Urethral strictures were created in rabbits (n = 5) by electrocautery and an ELUS technique was developed for subsequent luminal imaging. A 3.2F 40 MHz ultrasound (US) probe was introduced transurethrally and infused with US contrast agent. Images were recorded as the catheter was pulled back at a constant speed to acquire tomographic images. Lumen CSA over the entire urethral length was calculated using a custom methodology and validated in our laboratory.

RESULTS

Urethral luminal CSA over the entire length of urethra before and after experimental stricture development was quantified including the length of stenosis. Intra- and interobserver variability (r = 0.99 for both) was excellent.

CONCLUSIONS

Feasibility of ELUS as a quantitative technique to determine healthy urethral lumen and stricture CSA was demonstrated. The translational potential for a nonionizing imaging modality to better describe CSA, length, location, and uninvolved urethral CSA of the stricture is a significant improvement over current methodology.

Hemostatic Parameters in Newborn - II. Sequential Study During the First Four Weeks of Life

A sequential study of kaolin cephalin clotting time (KCCT), prothrombin time (PT), thrombin time (TT), plasma fibrinogen and serum FDP was conducted during the first four weeks of life on term and preterm babies. A “physiological dip” of PT and TT was noted inappropriate for gestational age (AGA) babies both term and preterm; in case of KCCT, the dip was significant in term AGA babies only. At the end of four weeks, PT and TT had moderately improved in term babies but showed little improvement in preterm ones; KCCT reached almost an adult value in all babies except in preterm AGA and term LGA (large for gestational age) ones. Plasma fibrinogen showed no “physiological dip” and reached adult level in two to four weeks. Serum FDP levels were appreciably raised in preterm AGA babies only at birth and there too normalised by 72 h.

Hemostatic Parameters in Newborn - I. Effect of Gestation and Rate of Intrauterine Growth

The present study comprises of 208 term, 159 preterm and 18 post-term neonates born to mothers with no history of drug intake or any disease likely to effect coagulation of the newborn. PT, TT and KCCT were relatively prolonged and plasma fibrinogen reduced to varying degree in newborns (as compared to adults). There was further prolongation of TT and reduction in plasma fibrinogen levels amongst preterm newborns as compared to term babies; TT was more prolonged amongst post-term babies also. PT was significantly more prolonged till 30 weeks of gestation, after which a near plateau was formed. KCCT showed significant improvement after 33 weeks and a further trend to normalisation after 38 weeks of gestation. Serum FDP values showed too much of variation for any meaningful statistical analysis but generally FDPs were higher in preterm babies. Intrauterine growth rate had no significant effect on these parameters amongst preterms -similar values for SGA (small for gestational age), AGA (appropriate for gestational age) and LGA (large for gestational age). On the other hand, amongst term babies SGA neonates had significantly prolonged PT and low plasma fibrinogen as compared to AGA; LGA babies also showed more prolongation of TT as compared to AGA.

Characterization of age-related penile microvascular hemodynamic impairment using laser speckle contrast imaging: possible role of increased fibrogenesis

Current technology for penile hemodynamic evaluations in small animals is invasive and has limitations. We evaluated a novel laser speckle contrast imaging (LSCI) technique to determine age‐related changes in penile microvascular perfusion (PMP) and tested the role of cavernosal muscle (CC) fibrosis mediated by Wnt‐TGF β1 signaling pathways in a mouse model. Ten young (2–3 months) and old (24–28 months) wild‐type C57BL6 male mice were subjected to PMP measured using a LSCI system. Penile blood flow (PBF, peak systolic velocity, PSV) was also measured using a color Doppler ultrasound for comparison. Measurements were made before and after injection of vasoactive drugs: prostaglandin E₁ (PGE₁) and acetylcholine (ACh). CC was processed for immunohistochemical studies for markers of endothelium and fibrosis. Protein levels were quantified by Western blot.PMP and PBF increased significantly from baseline after injection of vasoactive drugs. Peak PMP after PGE₁ and ACh was higher in young mice (225.0 ± 12.0 and 211.3 ± 12.1 AU) compared to old (155.9 ± 7.1 and 162.6 ± 5.1 AU, respectively). PSV after PGE₁ was higher in young than old mice (112.7 ± 8.5 vs. 78.2 ± 4.6 mm/sec). PSV after ACh was also higher in young (112.7 ± 5.6 mm/sec) than older mice (69.2 ± 7.1 mm/sec). PMP positively correlated with PSV (r = 0.867, P = 0.001). Immunostaining and Western blot showed increased protein expression of all fibrosis markers with aging. LSCI is a viable technique for evaluating penile hemodynamics. Increased cavernosal fibrosis may cause impaired penile hemodynamics and increased incidence of erectile dysfunction in older men.

Intracoronary Gene Transfer of Adenylyl Cyclase 6 in Patients With Heart Failure: A Randomized Clinical Trial

IMPORTANCE

Gene transfer has rarely been tested in randomized clinical trials.

OBJECTIVE

To evaluate the safety and efficacy of intracoronary delivery of adenovirus 5 encoding adenylyl cyclase 6 (Ad5.hAC6) in heart failure.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, double-blind, placebo-controlled, phase 2 clinical trial was conducted in US medical centers (randomization occurred from July 19, 2010, to October 30, 2014). Participants 18 to 80 years with symptomatic heart failure (ischemic and nonischemic) and an ejection fraction (EF) of 40% or less were screened; 86 individuals were enrolled, and 56 were randomized. Data analysis was of the intention-to-treat population. Participants underwent exercise testing and measurement of left ventricular EF (echocardiography) and then cardiac catheterization, where left ventricular pressure development (+dP/dt) and decline (-dP/dt) were recorded. Participants were randomized (3:1 ratio) to receive 1 of 5 doses of intracoronary Ad5.hAC6 or placebo. Participants underwent a second catheterization 4 weeks later for measurement of dP/dt. Exercise testing and EF were assessed 4 and 12 weeks after randomization.

INTERVENTIONS

Intracoronary administration of Ad5.hAC6 (3.2 × 109 to 1012 virus particles) or placebo.

MAIN OUTCOMES AND MEASURES

Primary end points included exercise duration and EF before and 4 and 12 weeks after randomization and peak rates of +dP/dt and -dP/dt before and 4 weeks after randomization. Fourteen placebo participants were compared (intention to treat) with 24 Ad5.hAC6 participants receiving the highest 2 doses (D4 + 5).

RESULTS

Fifty-six individuals were randomized and monitored for up to 1 year. Forty-two participants (75%) received Ad5.hAC6 (mean [SE] age, 63 [1] years; EF, 30% [1%]), and 14 individuals (25%) received placebo (age, 62 [1] years; EF, 30% [2%]). Exercise duration showed no significant group differences (4 weeks, P = .27; 12 weeks, P = .47, respectively). The D4 + 5 participants had increased EF at 4 weeks (+6.0 [1.7] EF units; n = 21; P < .004), but not 12 weeks (+3.0 [2.4] EF units; n = 21; P = .16). Placebo participants showed no increase in EF at 4 weeks or 12 weeks. Exercise duration showed no between-group differences (4-week change from baseline: placebo, 27 [36] seconds; D4 + 5, 44 [25] seconds; P = .27; 12-week change from baseline: placebo, 44 [28] seconds; D4 + 5, 58 [29 seconds, P = .47). AC6 gene transfer increased basal left ventricular peak -dP/dt (4-week change from baseline: placebo, +93 [51] mm Hg/s; D4 + 5, -39 [33] mm Hg/s; placebo [n = 21]; P < .03); AC6 did not increase arrhythmias. The admission rate for patients with heart failure was 9.5% (4 of 42) in the AC6 group and 28.6% (4 of 14) in the placebo group (relative risk, 0.33 [95% CI, 0.08-1.36]; P = .10).

CONCLUSIONS AND RELEVANCE

AC6 gene transfer safely increased LV function beyond standard heart failure therapy, attainable with one-time administration. Larger trials are warranted.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00787059.

Age-related external anal sphincter muscle dysfunction and fibrosis: possible role of Wnt/β-catenin signaling pathways

Studies show an age-related increase in the prevalence of anal incontinence and sphincter muscle atrophy. The Wnt/β-catenin signaling pathway has been recently recognized as the major molecular pathway involved in age-related skeletal muscle atrophy and fibrosis. The goals of our study were to 1) evaluate the impact of normal aging on external anal sphincter (EAS) muscle length-tension (L-T) function and morphology and 2) specifically examine the role of Wnt signaling pathways in anal sphincter muscle fibrosis. New Zealand White female rabbits [6 young (6 mo of age) and 6 old (36 mo of age)] were anesthetized, and anal canal pressure was measured to determine the L-T function of EAS. Animals were killed at the end of the study, and the anal canal was harvested and processed for histochemical studies (Masson trichrome stain for muscle/connective tissue) as well as for molecular markers for fibrosis and atrophy [collagen I, β-catenin, transforming growth factor-β (TGF-β), atrogin-1, and muscle-specific RING finger protein-1 (MuRF-1)]. The L-T was significantly impaired in older animals compared with young animals. Anal canal sections stained with trichrome showed a significant decrease in the muscle content (52% in old compared with 70% in young) and an increase in the connective tissue/collagen content in the old animals. An increased protein and mRNA expression of all the fibrosis markers was seen in the older animals. Aging EAS muscle exhibits impairment of function and increase in connective tissue. Upregulation of atrophy and profibrogenic proteins with aging may be the reason for the age-related decrease in anal sphincter muscle thickness and function.NEW & NOTEWORTHY Our studies using a female rabbit model show age-related alterations in the structure and function of the external anal sphincter (EAS) muscle. We used endoluminal ultrasound to measure age-related changes in EAS muscle thickness. We employed Western blot and quantitative PCR to demonstrate age-related changes in the levels of important fibrogenic as well as atrophy markers. Our findings may have significant clinical implications, i.e., use of specific antagonists to prevent age-related EAS muscle dysfunction.

Altered Penile Caveolin Expression in Diabetes: Potential Role in Erectile Dysfunction

BACKGROUND

The pathophysiology of increased severity of erectile dysfunction in men with diabetes and their poor response to oral pharmacotherapy are unclear. Defective vascular endothelium and consequent impairment in the formation and action of nitric oxide (NO) are implicated as potential mechanisms. Endothelial NO synthase, critical for NO generation, is localized to caveolae, plasma membrane lipid rafts enriched in structural proteins, and caveolins. Type 2 diabetes mellitus (T2DM)-induced changes in caveolin expression are recognized to play a role in cardiovascular dysfunction.

AIMS

To evaluate DM-related changes to male erectile tissue in a mouse model that closely resembles human T2DM and study the specific role of caveolins in penile blood flow and microvascular perfusion using mice lacking caveolin (Cav)-1 or Cav-3.

METHODS

We used wild-type C57BL6 (control) and Cav-1 and Cav-3 knockout (KO) male mice. T2DM was induced by streptozotocin followed by a high-fat diet for 4 months. Penile expressions of Cav-1, Cav-3, and endothelial NO synthase were determined by western blot, and phosphodiesterase type 5 activity was measured using [3H] cyclic guanosine monophosphate as a substrate. For hemodynamic studies, Cav-1 and Cav-3 KO mice were anesthetized, and penile blood flow (peak systolic velocity and end-diastolic velocity; millimeters per second) was determined using a high-frequency and high-resolution digital imaging color Doppler system. Penile tissue microcirculatory blood perfusion (arbitrary perfusion units) was measured using a novel PeriCam PSI system.

OUTCOMES

Penile erectile tissues were harvested for histologic studies to assess Cav-1, Cav-3, and endothelial NO synthase expression, phosphodiesterase type 5 activity, and blood flow, and perfusion measurements were assessed for hemodynamic studies before and after an intracavernosal injection of prostaglandin E1 (50 ng).

RESULTS

In T2DM mice, decreased Cav-1 and Cav-3 penile protein expression and increased phosphodiesterase type 5 activity were observed. Decreased response to prostaglandin E1 in peak systolic velocity (33 ± 4 mm/s in Cav-1 KO mice vs 62 ± 5 mm/s in control mice) and perfusion (146 ± 12 AU in Cav-1 KO mice vs 256 ± 12 AU in control mice) was observed. Hemodynamic changes in Cav-3 KO mice were insignificant.

CLINICAL TRANSLATION

Our findings provide novel mechanistic insights into erectile dysfunction severity and poor pharmacotherapy that could have potential application to patients with T2DM.

STRENGTHS AND LIMITATIONS

Use of KO mice and novel hemodynamic techniques are the strengths. A limitation is the lack of direct evaluation of penile hemodynamics in T2DM mice.

CONCLUSION

Altered penile Cav-1 expression in T2DM mice and impaired penile hemodynamics in Cav-1 KO mice suggests a regulatory role for Cav-1 in DM-related erectile dysfunction. Parikh J, Zemljic-Harpf A, Fu J, et al. Altered Penile Caveolin Expression in Diabetes: Potential Role in Erectile Dysfunction. J Sex Med 2017;14:1177-1186.

Wnt-β Catenin Signaling Pathway: A Major Player in the Injury Induced Fibrosis and Dysfunction of the External Anal Sphincter

Wnt-β catenin is an important signaling pathway in the genesis of fibrosis in many organ systems. Our goal was to examine the role of Wnt pathway in the external anal sphincter (EAS) injury-related fibrosis and muscle dysfunction. New Zealand White female rabbits were subjected to surgical EAS myotomy and administered local injections of either a Wnt antagonist (sFRP-2; daily for 7 days) or saline. Anal canal pressure and EAS length-tension (L-T) were measured for 15 weeks after which the animals were sacrificed. Anal canal was harvested and processed for histochemical studies (Masson trichrome stain), molecular markers of fibrosis (collagen and transforming growth factor-β) and immunostaining for β catenin. Surgical myotomy of the EAS resulted in significant impairment in anal canal pressure and EAS muscle L-T function. Following myotomy, the EAS muscle was replaced with fibrous tissue. Immunostaining revealed β catenin activation and molecular studies revealed 1.5–2 fold increase in the levels of markers of fibrosis. Local injection of sFRP-2 attenuated the β catenin activation and fibrosis. EAS muscle content and function was significantly improved following sFRP-2 treatment. Our studies suggest that upregulation of Wnt signaling is an important molecular mechanism of injury related EAS muscle fibrosis and sphincter dysfunction.

Dengue Fever-induced Thrombotic Microangiopathy: An Unusual Cause of Renal Failure

Dengue fever is a tropical infection, which is mosquito-borne disease, caused by dengue virus and spread by Aedes mosquitoes. The incidence of dengue fever has risen rapidly over the past few years. About half of dengue infections are asymptomatic, and a great majority present with fever and body ache. However, the occurrence of complications is well known, including acute kidney injury (AKI). AKI in dengue is usually attributable to a pre-renal cause. Thrombotic microangiopathy is an extremely rare complication of dengue fever, with only a few published case reports in medical literature. This case intends to highlight the importance of recognizing dengue fever-induced thrombotic microangiopathy by physicians and pathologists, enabling better diagnosis and management of this life-threatening condition.

Clinical Evaluation of Heart Failure: Agreement among Tests

Methods commonly used clinically to assess cardiac function in patients with heart failure include ejection fraction (EF), exercise treadmill testing (ETT), and symptom evaluation. Although these approaches are useful in evaluating patients with heart failure, there are at times substantial mismatches between individual assessments. For example, ETT results are often discordant with EF, and patients with minimal symptoms sometimes have surprisingly low EFs. To better define the relationship of these methods of assessment, we studied 56 patients with heart failure with reduced EF (HFrEF) who underwent measurement of ETT duration, EF by echocardiography, quantitative symptom evaluation, and LV peak dP/dt (rate of left ventricular pressure development and decline, measured invasively). Correlations were determined among these four tests in order to assess the relationship of EF, ETT, and symptoms against LV peak dP/dt. In addition, we sought to determine whether EF, ETT, and symptoms correlated with each other. Overall, correlations were poor. Only 15 of 63 total correlations (24%) were significant (p < 0.05). EF correlated most closely with LV peak -dP/dt. Linear regression analysis indicated that EF, ETT, and symptoms taken together predicted LV peak dP/dt better than any one measure alone. We conclude that clinical tests used to assess LV function in patients with HFrEF may not be as accurate or correlate as well as expected. All three clinical measures considered together may be the best representation of cardiac function in HFrEF patients currently available.

Circular and longitudinal muscles shortening indicates sliding patterns during peristalsis and transient lower esophageal sphincter relaxation

Esophageal axial shortening is caused by longitudinal muscle (LM) contraction, but circular muscle (CM) may also contribute to axial shortening because of its spiral morphology. The goal of our study was to show patterns of contraction of CM and LM layers during peristalsis and transient lower esophageal sphincter (LES) relaxation (TLESR). In rats, esophageal and LES morphology was assessed by histology and immunohistochemistry, and function with the use of piezo-electric crystals and manometry. Electrical stimulation of the vagus nerve was used to induce esophageal contractions. In 18 healthy subjects, manometry and high frequency intraluminal ultrasound imaging during swallow-induced esophageal contractions and TLESR were evaluated. CM and LM thicknesses were measured (40 swallows and 30 TLESRs) as markers of axial shortening, before and at peak contraction, as well as during TLESRs. Animal studies revealed muscular connections between the LM and CM layers of the LES but not in the esophagus. During vagal stimulated esophageal contraction there was relative movement between the LM and CM. Human studies show that LM-to-CM (LM/CM) thickness ratio at baseline was 1. At the peak of swallow-induced contraction LM/CM ratio decreased significantly (<1), whereas the reverse was the case during TLESR (>2). The pattern of contraction of CM and LM suggests sliding of the two muscles. Furthermore, the sliding patterns are in the opposite direction during peristalsis and TLESR.

Myoarchitectural and functional alterations in rabbit external anal sphincter muscle following experimental surgical trauma

Obstetrical trauma to external anal sphincter (EAS) is extremely common; however, its role in the development of anal incontinence is not clear. We examined the regenerative process and functional impact of experimental surgical trauma to EAS muscle in an animal model. Surgical myotomy, a craniocaudal incision extending along the entire length and thickness of the EAS, was performed in rabbits. Animals were allowed to recover, and anal pressures were recorded at weekly intervals for 12 wk using a custom-designed probe system to determine the length-tension property of EAS muscle. Animals were killed at predetermined time intervals, and the anal canal was harvested for histochemical studies (for determination of muscle/connective tissue/collagen) and sarcomere length measurement. In addition, magnetic resonance diffusion tensor imaging (MR-DTI) and fiber tracking was performed to determine myoarchitectural changes in the EAS. Myotomy of the EAS muscle resulted in significant impairment of its length-tension property that showed only partial recovery during the 12-wk study period. Histology revealed marked increase in the fibrosis (connective tissue = 69% following myotomy vs. 28% in controls) at 3 wk, which persisted at 12 wk. Immunostaining studies confirmed deposition of collagen in the fibrotic tissue. There was no change in the sarcomere length following myotomy. MR-DTI studies revealed disorganized muscle fiber orientation in the regenerating muscle. We conclude that, following experimental injury, the EAS muscle heals with an increase in the collagen content and loss of normal myoarchitecture, which we suspect is the cause of impaired EAS function.

Esophageal distension during bolus transport: can it be detected by intraluminal impedance recordings?

BACKGROUND

Esophageal multiple intraluminal impedance (MII) measurement has been used to detect gastro-esophageal reflux and bolus transport. It is not clear if MII can detect changes in luminal cross sectional area (CSA) during bolus transport. Intraluminal ultrasound (US) images, MII, and high resolution manometry (HRM) were recorded simultaneously to determine temporal relationship between CSA and impedance during esophageal bolus transport and to define the relationship between peak distension and nadir impedance.

METHODS

Studies were conducted in five healthy subjects. MII, HRM, and US images were recorded 6 cm above LES. Esophageal distensions were studied during swallows and injections of 0.5 N saline bolus into the esophagus.

KEY RESULTS

Temporal change in esophageal CSA correlates with changes in impedance (r-value: mean ± SD = -0.80 ± 0.08, range: -0.94 to -0.66). Drop in impedance during distension occurs as a two-step process; initial large drop associated with onset of CSA increase, followed by a small drop during which majority of the CSA increase occurs. Peak CSA and nadir impedance occur within 1 s of each other. Increase in swallow and injection volumes increased the CSA, had no effect on large drop but increased the small drop amplitude. We observed a significant correlation between peak CSA and nadir impedance (r = -0.90, p < 0.001) and a better correlation between peak CSA and inverse impedance (r = 0.94, p < 0.001).

CONCLUSIONS & INFERENCES

Further studies are needed to confirm that intraluminal impedance recordings may be used to measure luminal CSA during esophageal bolus transport.

Purse-string morphology of external anal sphincter revealed by novel imaging techniques

The external anal sphincter (EAS) may be injured in 25-35% of women during the first and subsequent vaginal childbirths and is likely the most common cause of anal incontinence. Since its first description almost 300 years ago, the EAS was believed to be a circular or a "donut-shaped" structure. Using three-dimensional transperineal ultrasound imaging, MRI, diffusion tensor imaging, and muscle fiber tracking, we delineated various components of the EAS and their muscle fiber directions. These novel imaging techniques suggest "purse-string" morphology, with "EAS muscles" crossing contralaterally in the perineal body to the contralateral transverse perineal (TP) and bulbospongiosus (BS) muscles, thus attaching the EAS to the pubic rami. Spin-tag MRI demonstrated purse-string action of the EAS muscle. Electromyography of TP/BS and EAS muscles revealed their simultaneous contraction and relaxation. Lidocaine injection into the TP/BS muscle significantly reduced anal canal pressure. These studies support purse-string morphology of the EAS to constrict/close the anal canal opening. Our findings have implications for the effect of episiotomy on anal closure function and the currently used surgical technique (overlapping sphincteroplasty) for EAS reconstructive surgery to treat anal incontinence.

Anatomical disruption and length-tension dysfunction of anal sphincter complex muscles in women with fecal incontinence

BACKGROUND

Anal sphincter complex muscles, the internal anal sphincter, external anal sphincter, and puborectalis muscles, play an important role in the anal continence mechanism. Patients with symptoms of fecal incontinence have weak anal sphincter complex muscles; however, their length-tension properties and relationship to anatomical disruption have never been studied.

OBJECTIVE

This study aimed to assess the anatomy of the anal sphincter complex muscles with the use of a 3-dimensional ultrasound imaging system and to determine the relationship between the anatomical defects and the length-tension property of external anal sphincter and puborectalis muscles in women with incontinence symptoms and in control subjects.

DESIGN

Severity of anal sphincter muscle damage was determined by static and dynamic 3-dimensional ultrasound imaging. The length-tension property was determined by anal and vaginal pressure with the use of custom-designed probes.

PATIENTS

Forty-four asymptomatic controls and 24 incontinent patients participated in this study.

MAIN OUTCOME MEASURES

The anatomical defects and length-tension dysfunction of anal sphincter complex muscles in patients with fecal incontinence were evaluated.

RESULTS

The prevalence of injury to sphincter muscles is significantly greater in the incontinent patients than in the controls. Eighty-five percent of patients but only 9% controls reveal damage to ≥2 of the 3 muscles of the anal sphincter complex. Anal and vaginal squeeze pressures increased with the increase in the probe size (length-tension curve) in the majority of controls. In patients, the increase in anal and vaginal squeeze pressures was either significantly smaller than in controls or it decreased with the increasing probe size (abnormal length-tension).

LIMITATIONS

We studied patients with severe symptoms. Whether our findings are applicable to patients with mild to moderate symptoms remains to be determined.

CONCLUSIONS

The length-tension property of the external anal sphincter and puborectalis muscles is significantly impaired in incontinent patients. Our findings have therapeutic implications for the treatment of anal incontinence.

Longitudinal muscle dysfunction in achalasia esophagus and its relevance

Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high-resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and "angina like" pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.

Esophageal wall blood perfusion during contraction and transient lower esophageal sphincter relaxation in humans

We recently reported that esophageal contraction reduces esophageal wall perfusion in an animal study. Our aim was to determine esophageal wall blood perfusion (EWBP) during esophageal contraction and transient lower esophageal sphincter relaxations (TLESRs) in humans. We studied 12 healthy volunteers. A custom-designed laser Doppler probe was anchored to the esophageal wall, 4-6 cm above the LES, by use of the Bravo pH system so that the laser light beam stay directed toward the esophageal mucosa. A high-resolution manometry equipped with impedance electrodes recorded esophageal pressures and reflux events. Synchronized pressure, impedance, pH, and EWBP recordings were obtained during dry and wet swallows and following a meal. Stable recordings of laser Doppler EWBP were only recorded when the laser Doppler probe was firmly anchored to the esophageal wall. Esophageal contractions induced by dry and wet swallows resulted in 46 ± 9% and 60 ± 10% reduction in the EWBP, respectively (compared to baseline). Reduction in EWBP was directly related to the amplitude (curvilinear fit) and duration of esophageal contraction. Atropine reduced the esophageal contraction amplitude and decreased the EWBP reduction associated with esophageal contraction. TLESRs were also associated with reduction in the EWBP, albeit of smaller amplitude (29 ± 3%) but longer duration (19 ± 2 s) compared with swallow-induced esophageal contractions. We report 1) an innovative technique to record EWBP for extended time periods in humans and 2) contraction of circular and longitudinal muscle during peristalsis and selective longitudinal muscle contraction during TLESR causes reduction in the EWBP; 3) using our innovative technique, future studies may determine whether esophageal wall ischemia is the cause of esophageal pain/heartburn.

Role of puborectalis muscle in the genesis of urethral pressure

PURPOSE

The internal (smooth muscle) and the external (rhabdosphincter striated muscle) urethral sphincters have important roles in the genesis of urethral closure pressure. The U-shaped pelvic floor puborectalis muscle is important in the closure of anal and vaginal orifices in humans. We defined the contribution of the puborectalis to urethral pressure.

MATERIALS AND METHODS

A total of 11 female rabbits were anesthetized and prepared to measure urethral, vaginal and anal canal pressure using manometric methods. Pressure was recorded at rest, after administration of pharmacological agents and during electrical stimulation of the puborectalis and rhabdosphincter sphincter muscles. Phenylephrine, sodium nitroprusside (Sigma-Aldrich®) and rocuronium bromide (PharMEDium, Lake Forest, Illinois) were used to define the relative contribution of smooth and striated muscles to urethral pressure. Histology of the pelvic floor hiatus was also studied.

RESULTS

At rest mean ± SEM maximum urethral pressure was 13 ± 6 mm Hg. Sodium nitroprusside (50 μg/kg) infusion resulted in a 30% to 40% decrease in resting urethral pressure (mean 7.2 ± 0.2 mm Hg). Phenylephrine produced a dose dependent increase in urethral pressure (mean 17 ± 6, 25 ± 5 and 29 ± 6 for 5, 10 and 50 μg/kg intravenously, respectively). Electrical stimulation of the puborectalis muscle induced a stimulus dependent increase in urethral, vaginal and anal canal pressure. On the other hand, rhabdosphincter stimulation induced a stimulus intensity dependent increase in urethral pressure only. The increase in urethral pressure after puborectalis muscle stimulation was more than twofold higher than after rhabdosphincter stimulation.

CONCLUSIONS

Our data prove that the puborectalis, a component of the pelvic floor muscles, is an important contributor to urethral pressure in the rabbit.

A novel pattern of longitudinal muscle contraction with subthreshold pharyngeal stimulus: a possible mechanism of lower esophageal sphincter relaxation

A subthreshold pharyngeal stimulus induces lower esophageal sphincter (LES) relaxation and inhibits progression of ongoing peristaltic contraction in the esophagus. Recent studies show that longitudinal muscle contraction of the esophagus may play a role in LES relaxation. Our goal was to determine whether a subthreshold pharyngeal stimulus induces contraction of the longitudinal muscle of the esophagus and to determine the nature of this contraction. Studies were conducted in 16 healthy subjects. High resolution manometry (HRM) recorded pressures, and high frequency intraluminal ultrasound (HFIUS) images recorded longitudinal muscle contraction at various locations in the esophagus. Subthreshold pharyngeal stimulation was induced by injection of minute amounts of water in the pharynx. A subthreshold pharyngeal stimulus induced strong contraction and caudal descent of the upper esophageal sphincter (UES) along with relaxation of the LES. HFIUS identified longitudinal muscle contraction of the proximal (3-5 cm below the UES) but not the distal esophagus. Pharyngeal stimulus, following a dry swallow, blocked the progression of dry swallow-induced peristalsis; this was also associated with UES contraction and descent along with the contraction of longitudinal muscle of the proximal esophagus. We identify a unique pattern of longitudinal muscle contraction of the proximal esophagus in response to subthreshold pharyngeal stimulus, which we propose may be responsible for relaxation of the distal esophagus and LES through the stretch sensitive activation of myenteric inhibitory motor neurons.

Ambulatory high-resolution manometry, lower esophageal sphincter lift and transient lower esophageal sphincter relaxation

BACKGROUND

Lower esophageal sphincter (LES) lift seen on high-resolution manometry (HRM) is a possible surrogate marker of the longitudinal muscle contraction of the esophagus. Recent studies suggest that longitudinal muscle contraction of the esophagus induces LES relaxation.

AIM

Our goal was to determine: (i) the feasibility of prolonged ambulatory HRM and (ii) to detect LES lift with LES relaxation using ambulatory HRM color isobaric contour plots.

METHODS

In vitro validation studies were performed to determine the accuracy of HRM technique in detecting axial movement of the LES. Eight healthy normal volunteers were studied using a custom designed HRM catheter and a 16 channel data recorder, in the ambulatory setting of subject's home environment. Color HRM plots were analyzed to determine the LES lift during swallow-induced LES relaxation as well as during complete and incomplete transient LES relaxations (TLESR).

KEY RESULTS

Satisfactory recordings were obtained for 16 h in all subjects. LES lift was small (2 mm) in association with swallow-induced LES relaxation. LES lift could not be measured during complete TLESR as the LES is not identified on the HRM color isobaric contour plot once it is fully relaxed. On the other hand, LES lift, mean 8.4 ± 0.6 mm, range: 4-18 mm was seen with incomplete TLESRs (n = 80).

CONCLUSIONS & INFERENCES

Our study demonstrates the feasibility of prolonged ambulatory HRM recordings. Similar to a complete TLESR, longitudinal muscle contraction of the distal esophagus occurs during incomplete TLESRs, which can be detected by the HRM. Using prolonged ambulatory HRM, future studies may investigate the temporal correlation between abnormal longitudinal muscle contraction and esophageal symptoms.

Effect of esophageal contraction on esophageal wall blood perfusion

Myocardial blood flow occurs during the diastolic phase of the cardiac cycle, because myocardial contraction during the systolic phase impedes myocardial perfusion. Using laser Doppler perfusion technique, we studied the effect of esophageal contraction on the esophageal wall perfusion. Studies were conducted in rats. A laser Doppler probe was anchored to the esophageal wall, and wall perfusion was studied under various experimental conditions. Increase and decrease in the systemic blood pressure induced by different pharmacological agents was associated with the increase and decrease in the esophageal wall perfusion, respectively. Esophageal contractions induced by electrical stimulation of the vagus nerve and electrical stimulation of the muscle directly resulted in a reduction in the esophageal wall perfusion, in a dose-dependent fashion. Esophageal wall perfusion could be monitored by placing the Doppler probe on the esophageal mucosa or on the outside of the esophageal wall. Esophageal contraction impedes entry of blood into the esophageal wall. Future studies may investigate if ischemia of the esophageal wall induced by sustained esophageal contractions/esophageal spasm is the cause of esophageal pain symptoms in humans.

Variability in the muscle composition of rat esophagus and neural pathway of lower esophageal sphincter relaxation

Several studies from our laboratory show that axial stretch of the lower esophageal sphincter (LES) in an oral direction causes neurally mediated LES relaxation. Under physiological conditions, axial stretch of the LES is caused by longitudinal muscle contraction (LMC) of the esophagus. Because longitudinal muscle is composed of skeletal muscle in mice, vagal-induced LMC and LES relaxation are both blocked by pancuronium. We conducted studies in rats (thought to have skeletal muscle esophagus) to determine if vagus nerve-mediated LES relaxation is also blocked by pancuronium. LMC-mediated axial stretch on the LES was monitored using piezoelectric crystals. LES and esophageal pressures were monitored with a 2.5-Fr solid-state pressure transducer catheter. Following bilateral cervical vagotomy, the vagus nerve was stimulated electrically. LES, along with the esophagus, was harvested after in vivo experiments and immunostained for smooth muscle (smooth muscle α-actin) and skeletal muscle (fast myosin heavy chain). Vagus nerve-stimulated LES relaxation and esophageal LMC were reduced in a dose-dependent fashion and completely abolished by pancuronium (96 μg/kg) in six rats (group 1). On the other hand, in seven rats, LES relaxation and LMC were only blocked completely by a combination of pancuronium (group 2) and hexamethonium. Immunostaining revealed that the longitudinal muscle layer was composed of predominantly skeletal muscle in the group 1 rats. On the other hand, the longitudinal muscle layer of group 2 rats contained a significant amount of smooth muscle (P < 0.05). Our study shows tight coupling between axial stretch on the LES and relaxation of the LES, which suggests a cause and effect relationship between the two. We propose that the vagus nerve fibers that cause LMC induce LES relaxation through the stretch-sensitive activation of inhibitory motor neurons.

Functional morphology of anal sphincter complex unveiled by high definition anal manometery and three dimensional ultrasound imaging

BACKGROUND

Anal sphincter complex consists of anatomically overlapping internal anal sphincter (IAS), external anal sphincter (EAS) and puborectalis muscle (PRM). We determined the functional morphology of anal sphincter muscles using high definition anal manometery (HDAM), three dimensional (3D)-ultrasound (US) and Magnetic resonance (MR) imaging.

METHODS

We studied 15 nulliparous women. High definition anal manometery probe equipped with 256 pressure transducers was used to measure the anal canal pressures at rest and squeeze. Lengths of IAS, PRM, and EAS were determined from the 3D-US images and superimposed on the HDAM plots. Movements of anorectal angle with squeeze were determined from the dynamic MR images.

KEY RESULTS

High definition anal manometery plots reveal that anal canal pressures are highly asymmetric in the axial and circumferential direction. Anal canal length determined by the 3D-US images is slightly smaller than that measured by HDAM. The EAS (1.9 ± 0.5 cm long) and PRM (1.7 ± 0.4 cm long) surround distal and proximal parts of the anal canal, respectively. With voluntary contraction, anal canal pressures increase in the proximal (PRM) and distal (EAS zone) parts of anal canal. Posterior peak pressure in the anal canal moves cranially in relation to the anterior peak pressure, with squeeze. Similar to the movement of peak posterior pressure, MR images show cranial movement of anorectal angle with squeeze.

CONCLUSIONS & INFERENCES

Our study proves that the PRM is responsible for the closure of the cranial part of anal canal. HDAM, in addition to measuring constrictor function can also record the elevator function of levator ani/pelvic floor muscles.

Swallow induces a peristaltic wave of distension that marches in front of the peristaltic wave of contraction

BACKGROUND

Current understanding is that swallow induces simultaneous inhibition of the entire esophagus followed by a sequential wave of contraction (peristalsis). We observed a pattern of luminal distension preceding contraction which suggested that inhibition may also traverses in a peristaltic fashion. Our aim is to determine the relationship between contraction and luminal distension during bolus transport.

METHODS

Eight subjects using two solid-state pressure and two ultrasound (US) transducers were studied. Synchronous pressure and US images were obtained with wet swallows and after edrophonium and atropine. Luminal cross-sectional area (CSA) at 2 cm and 12 cm above the lower esophageal sphincter (LES) were recorded. Relationship between pressure and CSA at each site, propagation velocity of peak pressure and peak distension waves were determined. Fluoroscopy coupled with manometry was also performed in five normal subjects.

KEY RESULTS

Esophageal distension precedes contraction wave at both-recorded sites. During distension, esophageal pressure remains constant while luminal CSA increases significantly. The onset and the peak of distension wave traverses in a peristaltic fashion between both sites. A tight coupling exists between the peak distension and peak contraction waves with similar velocities (3.7 cm s(-1) and 3.6 cm s(-1)) of propagation. The degree of distension is greater at 2 cm compared to 12 cm. Atropine and edrophonium reduced and increased the contraction pressure respectively, without affecting the distension wave. Fluoroscopic study confirmed that the wave of distension traverses the esophagus in a peristaltic fashion.

CONCLUSIONS & INFERENCES

Distension and contraction waves are tightly coupled to each other and both traverse in a peristaltic fashion.

Antireflux action of Nissen fundoplication and stretch-sensitive mechanism of lower esophageal sphincter relaxation

BACKGROUND & AIMS

Surgical fundoplication is an effective treatment for gastroesophageal reflux disease. One of the proposed mechanisms for its antireflux action is that it reduces lower esophageal sphincter (LES) relaxation. We investigated whether fundoplication works through a stretch-sensitive mechanism of LES relaxation.

METHODS

Studies were performed in rats. Intravenous and arterial lines were placed and tracheal intubation was performed. A midline laprotomy was performed to place sutures through the esophagus to exert axial stretch on the LES, and the vagus nerve was isolated in the neck for electrical stimulation. The LES pressure was monitored with a 2F solid-state pressure transducer placed through a gastrostomy. Cranial displacement of the LES was recorded using piezoelectric crystals. Data were recorded before and after 360-degree Nissen fundoplication.

RESULTS

Axial stretch and vagus nerve stimulation induced cranial displacement of the LES as well as LES relaxation in a dose-dependent manner. LES relaxation and axial stretch were each significantly reduced after fundoplication (P < .01). Nitric-oxide-induced LES relaxation was not affected by fundoplication. Removal of fundoplication restored axial stretch- and vagus nerve-stimulated LES relaxation as well as LES cranial displacement.

CONCLUSIONS

Fundoplication reduces LES relaxation by interfering with axial stretch on the LES. Based on this mechanism of the antireflux actions of fundoplication, it might be possible to design new surgical strategies to treat reflux disease and reduce complications of fundoplication surgery.