Current data processing methods and reporting standards for untargeted analysis of volatile organic compounds using direct mass spectrometry: a systematic review

INTRODUCTION

Untargeted direct mass spectrometric analysis of volatile organic compounds has many potential applications across fields such as healthcare and food safety. However, robust data processing protocols must be employed to ensure that research is replicable and practical applications can be realised. User-friendly data processing and statistical tools are becoming increasingly available; however, the use of these tools have neither been analysed, nor are they necessarily suited for every data type.

OBJECTIVES

This review aims to analyse data processing and analytic workflows currently in use and examine whether methodological reporting is sufficient to enable replication.

METHODS

Studies identified from Web of Science and Scopus databases were systematically examined against the inclusion criteria. The experimental, data processing, and data analysis workflows were reviewed for the relevant studies.

RESULTS

From 459 studies identified from the databases, a total of 110 met the inclusion criteria. Very few papers provided enough detail to allow all aspects of the methodology to be replicated accurately, with only three meeting previous guidelines for reporting experimental methods. A wide range of data processing methods were used, with only eight papers (7.3%) employing a largely similar workflow where direct comparability was achievable.

CONCLUSIONS

Standardised workflows and reporting systems need to be developed to ensure research in this area is replicable, comparable, and held to a high standard. Thus, allowing the wide-ranging potential applications to be realised.

A276 CANNABINOID RECEPTOR 1 IS LOCALIZED IN ENTERIC NEURONS AND EPITHELIUM IN FETAL AND EARLY POSTNATAL MOUSE INTESTINE

Background

The endocannabinoid system (ECS) is necessary for gastrointestinal (GI) homeostasis and serves as a target for exogenous medicinal and recreational cannabinoid compounds. While components of the ECS, including receptors, ligands, and biosynthetic/degradative enzymes, have been increasingly characterized in the adult GI tract of both humans and animal models, similar advances in understanding the role of the ECS in GI developmental programming have not yet been made.

Purpose

We tested the hypothesis that the ECS plays a role in the developmental programming of the GI tract.

Method

The developmental timeline of ECS component expression was investigated in the GI tract from fetal and early postnatal mice. Samples from timed-pregnant outbred mice were collected from embryonic days 14 (E14), E16, E18 and postnatal days 1 (P1), P7 and P28, representing a timeline of early colonization of the GI tract by enteric neurons (E14) to 1 week after weaning (P28). Localization of cannabinoid receptor 1 (CB1) expression was examined in fetal and postnatal small intestine by immunohistochemistry. Fetal intestine was processed for RNA extraction and relative expression of ECS components determined by RT-qPCR.

Result(s)

CB1 expression at E14 was observed in the outer wall of the gut and in the developing mucosa. By E18, expression of CB1 became more localized to the enteric plexuses and to mucosal epithelial cells. In postnatal ileum, at least >50% of myenteric ganglia were found to express CB1 from P1 to P28. CB1 expression continued to be present in the mucosal epithelium of ileum from P1 to P28, with a subset of CB1 expression in enterochromaffin cells, as identified by 5-HT immunolabeling. Significant decreases in expression of mRNA encoding CB1 (p<0.0001) and the ECS biosynthetic enzymes NAPE-PLD (p<0.05) and DAGLa (p<0.05) were found between E14 and E18.

Conclusion(s)

Components of the ECS are present in the fetal and early postnatal GI tract. Further research is needed to better characterize the roles and mechanisms of action of the ECS in GI development. The potential impact of exogenous cannabis exposure in early life, either by in utero exposure or via the use of medicinal cannabinoids in childhood, highlights the importance of identifying the contributions of the ECS to normal development.

Disclosure of Interest

None Declared

A241 KIWIFRUIT AND KIWIFRUIT EXTRACTS FOR TREATMENT OF CONSTIPATION: A SYSTEMATIC REVIEW AND META-ANALYSIS

Aims

This systematic review and meta-analysis aimed to determine the effectiveness of kiwifruit or kiwifruit extracts in thetreatment of constipation.

Methods

Electronic databases were searched from inception until January 2021. Eligible studies enrolled participants with functional constipation (FC) or irritable bowel syndrome with constipation (IBS-C) with randomization to receive kiwifruit or kiwifruit extracts vs. any non-kiwifruit control. Standardized meandifference (SMD) or mean difference (MD) with confidence intervals (CI) were determined for the following outcomes: weekly frequency of spontaneous bowel movements (SBM) and Bristol Stool Scale (BSS). GRADE approach was used to rate the certainty of evidence. PROSPERO registration number CRD42020207365.

Results

Seven randomized controlled trials including 399 participants (82% female; mean age 42 years [Standard Deviation 14.6]) were included. Compared with placebo, kiwifruit extract might increase weekly frequency of SBM (MD 1.36; 95% CI -0.44 to 3.16) with low certainty evidence. Kiwifruit had an uncertain effecton BSS (SMD 1.54; 95% CI -1.33 to 4.41) with very low certainty evidence. Compared with psyllium, kiwifruitmay increase weekly SBM (MD 1.1; 95% CI -0.02 to 2.04) and may increase BSS (softer stools) (MD 0.63;95% CI 0.01 to 1.25) both with low certainty evidence. Compared to placebo, kiwifruit encapsulated extracts may result in an increase in minor adverse events (Relative Risk 4.58; 95% CI 0.79 to 26.4).

Conclusions

Among individuals with constipation, overall low certainty of evidence indicate that kiwifruit may increase SBM when compared to placebo or psyllium. Although overall results are promising, establishing therole of kiwifruit in FC or IBS-C requires large, methodologically rigorous trials.

Funding Agencies

None

A246 GASTROINTESTINAL ADVERSE EVENTS OF CANNABINOIDS IN PEDIATRIC POPULATIONS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Use of therapeutic cannabinoids in the pediatric population has increased in recent years within areas of epilepsy, palliative care, and cancer. Given the endocannabinoid system plays a crucial role in gastrointestinal (GI) homeostasis, exogenous cannabinoids have the potential to develop GI related side effects. While some GI adverse events have been reported with the use of therapeutic cannabinoids, the full profile of GI adverse events in the pediatric population is still unknown.

Aims

To understand the impact of therapeutic cannabinoids on the GI system of pediatric patients, we performed a systematic review and meta-analysis to assess the prevalence of various GI-related adverse events arising from cannabinoid usage within pediatric populations.

Methods

Searches were conducted from OVID MEDLINE, EMBASE, CINAHL, Web of Science, and The Cochrane Library for study screening. The included studies were quantitatively assessed for GI adverse events including nausea, diarrhea, increased appetite, decreased appetite, weight gain, weight loss, constipation, abdominal pain, and unspecified events. The prevalence along with their relation towards diagnosis, type of cannabinoid, dosage, duration of treatment, and study type were also assessed.

Results

Among a total of 1201 patients across 25 included studies, an overall prevalence of 33.91% GI adverse events was observed in patients. The statistical analysis of the pediatric population displayed no relation between therapeutic cannabinoid usage and GI adverse events, bearing a large heterogeneity (I² = 91%, P < 0.01). Upon analysis based on study type, a significant difference was observed between prospective and retrospective studies in categories of all GI adverse events, diarrhea, and decreased appetite, with prospective studies displaying a higher prevalence in all three categories. Nausea symptoms showed a significant negative correlation with maximum dosage of cannabinoid used. In addition, diarrhea was found to have a higher prevalence in Dravet syndrome related to an ion channel gene mutation (SCN1A) compared to other epilepsy patients.

Conclusions

While the meta-analysis did not identify any significant associations between therapeutic cannabinoid usage and GI adverse events, there remains the potential for interactions of cannabinoids on GI symptoms depending on dosage and underlying patient factors.

Funding Agencies

Farncombe Family Digestive Health Research Institute

A68 THERAPEUTIC EFFECTS OF MEDICINAL CANNABINOIDS ON THE GASTROINTESTINAL SYSTEM IN PEDIATRIC PATIENTS: A SYSTEMATIC REVIEW

Background

Changes in cannabis legalization in recent years have led to an increasing interest in medicinal cannabinoids for a variety of therapeutic uses, including those which target the gastrointestinal tract. These effects are mediated by interactions with the endocannabinoid system. As this system is present in early life, it is important to ensure pediatric representation in clinical studies regarding cannabinoid use.

Aims

We conducted a systematic review to assess the efficacy of medicinal cannabinoids in treating gastrointestinal symptoms in pediatric patients.

Methods

A literature search of Medline, Embase, CINAHL, Web of Science and the Cochrane Library was conducted from inception. Study design, patient characteristics, type, dose and duration of medicinal cannabinoid therapy, and gastrointestinal outcomes were extracted.

Results

From 7,303 records identified, five studies met all inclusion criteria. The focus of the included studies ranged from chemotherapy-induced nausea, inflammatory bowel disease and gastrointestinal symptoms associated with severe complex motor disorders. Results varied based on the symptom being treated, the type of cannabinoid, and the patient population, however, the most consistently improved symptom was chemotherapy-induced nausea.

Conclusions

Medicinal cannabinoids may have a potential role in treating specific gastrointestinal symptoms in specific patient populations. The limited number and heterogenicity of included studies highlight the requirement for future research to distinguish the effects amongst different cannabinoid types, patient populations and examine drug-interactions. In addition, the molecular interplay between disease processes, the endocannabinoid system and medicinal cannabinoids require investigation to further understand the mechanisms behind this intervention.

Funding Agencies

Natural Sciences and Engineering Research Council of Canada; Farncombe Family Digestive Health Research Institute

A66 THE IMPACT OF A MULTIDISCIPLINARY ADOLESCENT AND YOUNG ADULT (AYA) INFLAMMATORY BOWEL DISEASE (IBD) ON CLINIC NO SHOW RATES

Background

Transitioning from pediatric to adult health care is associated with significant psychosocial and clinical morbidity. Adolescents not only transition their medical care, but also experience vast changes in the physical, social, and psychological spheres of their lives. The medical team must help navigate these changes to provide optimal care.

IBD in adolescence is associated with increased hospitalizations and surgery. This is due to several factors, including medication non-adherence and a failure to attend medical appointments. There has been a greater focus on improving care for this unique population.

McMaster Children’s Hospital has integrated the AYA IBD clinic for patients between the ages of 16 and 22. The goal is to transition patients using a developmentally appropriate framework to facilitate self-efficacy and help identify comorbid mental health conditions while building resilience.

Aims

To explore the impact of the implementation of a dedicated transition clinic on attendance at medical visits for AYA patients with IBD.

Methods

The total numbers of patients booked in the AYA IBD Clinic was compared to an age matched subset of the patients in the adult McMaster Complex IBD (CIBD) Clinic. These visits were assessed based on whether the visit was: attended, cancelled, or no showed. Visits were then stratified between in-person and virtual visits. Unpaired t tests was performed to compare the AYA IBD clinic and the CIBD clinic. Findings were deemed significant based on p-values <0.05.

Results

The percentages of patients that attended visits (in-person or virtually) was similar between both clinics at 86% versus 79% Year 1 (Y1) and 76% versus 81% Year 2 (Y2). The number of patients seen in the AYA clinic increased from Y1 (n=92) to Y2 (n=131). The CIBD clinic saw fewer patients between Y1 (n=202) and Y2 (n=79). There were a higher number of patients who cancelled or no showed in Y2 versus Y1 for the AYA virtual visits (13 versus 8) compared to the CIBD clinic (Y2,1 versus Y1,1).

Conclusions

Our results highlight the challenges of transitioning adolescent patients with IBD. Our retrospective study was not powered to show significance. Given the increase in cancellation and no-show rates in Y2, the AYA clinic has incorporated a patient navigator to issue reminder phone calls and facilitate communication with patients between clinics. Future studies will re-assess how the presence of a patient navigator impacts attendance and cancellation rates. Future studies will also assess how the AYA clinic impacts transition readiness and self-efficacy, which is being measured through validated questionnaires in our clinic.

Funding Agencies

Grants-In-Aid

Proceedings of the 2018 Advances In Motility and In NeuroGastroenterology: AIMING for the Future Single Topic Symposium

OBJECTIVES

Motility and functional disorders are common in children and often debilitating, yet these disorders remain challenging to treat effectively. At the 2018 Annual North American Society for Pediatric Gastroenterology, Hepatology and Nutrition meeting, the Neurogastroenterology and Motility Committee held a full day symposium entitled, 2018 Advances In Motility and In NeuroGastroenterology - AIMING for the future. The symposium aimed to explore clinical paradigms in pediatric gastrointestinal motility disorders and provided a foundation for advancing new scientific and therapeutic research strategies.

METHODS

The symposium brought together leading experts throughout North America to review the state of the art in the diagnosis and management of motility and functional disorders in children. Presentations were divided into esophageal, antral duodenal, and colorectal modules. Each module included oral presentations by experts in the respective fields, leading to thought-provoking discussions. There were 2 breakout sessions with small group discussions on select topics, focusing on defining scientific insights into the diagnosis and management of pediatric functional gastrointestinal and motility disorders in a systematic, segment-based approach.

CONCLUSIONS

The field of neurogastroenterology has made remarkable progress in the last decade. The current report summarizes the major learning points from the symposium highlighting the diagnosis and promising therapies on the horizon for pediatric neurogastrointestinal and motility disorders.

The cyclic motor patterns in the human colon

BACKGROUND

High-resolution colonic manometry gives an unprecedented window into motor patterns of the human colon. Our objective was to characterize motor activities throughout the entire colon that possessed persistent rhythmicity and spanning at least 5 cm.

METHODS

High-resolution colonic manometry using an 84-channel water-perfused catheter was performed in 19 healthy volunteers. Rhythmic activity was assessed during baseline, proximal balloon distention, meal, and bisacodyl administration.

KEY RESULTS

Throughout the entire colon, a cyclic motor pattern occurred either in isolation or following a high-amplitude propagating pressure wave (HAPW), consisting of clusters of pressure waves at a frequency centered on 11-13 cycles/min, unrelated to breathing. The cluster duration was 1-6 minutes; the pressure waves traveled for 8-27 cm, lasting 5-8 seconds. The clusters itself could be rhythmic at 0.5-2 cpm. The propagation direction of the individual pressure waves was mixed with >50% occurring simultaneous. This high-frequency cyclic motor pattern co-existed with the well-known low-frequency cyclic motor pattern centered on 3-4 cpm. In the rectum, the low-frequency cyclic motor pattern dominated, propagating predominantly in retrograde direction. Proximal balloon distention, a meal and bisacodyl administration induced HAPWs followed by cyclic motor patterns.

CONCLUSIONS AND INFERENCES

Within cyclic motor patterns, retrograde propagating, low-frequency pressure waves dominate in the rectum, likely keeping the rectum empty; and mixed propagation, high-frequency pressure waves dominate in the colon, likely promoting absorption and storage, hence contributing to continence. Propagation and frequency characteristics are likely determined by network properties of the interstitial cells of Cajal.

On the nature of high-amplitude propagating pressure waves in the human colon

Characterization of high-amplitude propagating pressure waves (HAPWs or HAPCs) plays a key role in diagnosis of colon dysmotility using any type of colonic manometry. With the introduction of high-resolution manometry, more insight is gained into this most prominent propulsive motor pattern. Here, we use a water-perfused catheter with 84 sensors with intervals between measuring points of 1 cm throughout the colon, for 6-8 h, in 19 healthy subjects. The catheter contained a balloon to evoke distention. We explored as stimuli a meal, balloon distention, oral prucalopride, and bisacodyl injection, with a goal to optimally evoke HAPWs. We developed a quantitative measure of HAPW activity, the "HAPW Index." Our protocol elicited 290 HAPWs. 21% of HAPWs were confined to the proximal colon with an average amplitude of 75.3 ± 3.3 mmHg and an average HAPW Index of 440 ± 58 mmHg·m·s. 29% of HAPWs started in the proximal colon and ended in the transverse or descending colon, with an average amplitude of 87.9 ± 3.1 mmHg and an average HAPW Index of 3,344 ± 356 mmHg·m·s. Forty-nine percent of HAPWs started and ended in the transverse or descending colon with an average amplitude of 109.3 ± 3.3 mmHg and an average HAPW Index of 2,071 ± 195 mmHg·m·s. HAPWs with and without simultaneous pressure waves (SPWs) initiated the colo-anal reflex, often abolishing 100% of anal sphincter pressure. Rectal bisacodyl and proximal balloon distention were the most optimal stimuli to evoke HAPWs. These measures now allow for a confident diagnosis of abnormal motility in patients with colonic motor dysfunction.NEW & NOTEWORTHY High-amplitude propagating pressure waves (HAPWs) were characterized using 84 sensors throughout the entire colon in healthy subjects, taking note of site of origin, site of termination, amplitude, and velocity, and to identify optimal stimuli to evoke HAPWs. Three categories of HAPWs were identified, including the associated colo-anal reflex. Proximal balloon distention and rectal bisacodyl were recognized as reliable stimuli for evoking HAPWs, and a HAPW Index was devised to quantify this essential colonic motor pattern.

A173 RECOGNIZING RARE PRESENTATIONS OF POLYPOSIS SYNDROMES AND THEIR ASSOCIATED MALIGNANCIES IN PEDIATRIC PATIENTS

Background

There is a range of polyposis syndromes and presentations in pediatrics. There are also associated extra-colonic malignancies of which to be cognizant when orchestrating the initial work-up of the various polyposis syndromes.

Aims

To use case review to highlight the importance of recognizing the breadth of presentations of polyposis syndromes in pediatrics.

Methods

Two recent pediatric presentations of polyposis with extra-intestinal manifestations were identified, chart review completed, and compared with newly published ESPGHAN guidelines.

Results

Two patients with intestinal polyposis are presented, in which extra-colonic malignancies and genetic mutations were identified.

The first patient presented at age 16 with a history of fatigue and abdominal pain, and was found to have pancytopenia and splenomegaly. Initial work up included a bone marrow biopsy that was normal. The patient then underwent upper and lower endoscopic evaluation for increasing abdominal pain and persistent anemia and was found to have polymorphic polyps in the duodenum, sigmoid and rectum. On pathology, polyps were mostly inflammatory, but one was found to be hamartomatous. Additional screening revealed a thyroid nodule, found to be follicular carcinoma, requiring hemithyroidectomy. The patient was confirmed to have a PTEN mutation and was diagnosed with Cowden syndrome; following this diagnosis proceeded with a prophylactic bilateral mastectomy.

The second patient was referred at age 15 with a strong family history of APC-associated FAP. At the time of consultation she was asymptomatic and she remained so throughout her work-up. Screening endoscopy revealed 70–90 recto-sigmoid adenomatous polyps as well as scattered gastric and duodenal polyps. Her initial work-up also uncovered an early papillary thyroid carcinoma. Her treatment included a total thyroidectomy and total proctocolectomy with J-pouch and ileoanal anastomosis. Follow-up endoscopy continues for surveillance of numerous gastric adenomas which to this point have not progressed to high-grade dysplasia or malignancy.

Conclusions

These 2 cases highlight the importance of recognizing that neoplastic conditions typically diagnosed in adulthood can also present in the pediatric age group. Ideally, further guidelines in pediatrics would be beneficial to ensure a consistent approach to investigating polyposis and associated malignancies. Pertaining to our specific patients, each had identification of a thyroid malignancy before the recommended screening age of 18 as per the currently accepted guideline, and neither were symptomatic. More cases are needed to establish if this earlier recognition of disease is meaningful in postulating potential mortality associated with a later diagnosis.

Funding Agencies

None

A45 INFLAMMATION AND INTESTINAL PERMEABILITY IN PEDIATRIC SHORT BOWEL SYNDROME

Background

Both intestinal dysbiosis and central-line associated blood stream infections (CLABSI) have been well documented in children with short bowel syndrome (SBS). Gastrointestinal microbiota prime and regulate mucosal immunity, therefore we hypothesize children with SBS may have longstanding increased intestinal permeability which could lead to mucosal inflammation and predispose to bacteremia.

Aims

We sought to investigate intestinal permeability as well as both intestinal and systemic activation of the inflammatory cascade in children with SBS.

Methods

Two cohorts of children with SBS were consented; with Group 1 including children with SBS requiring central venous catheter (CVC) for parenteral nutrition, and Group 2 including children with SBS without CVC. SBS groups were compared to three control groups including age and sex-matched children with CVC for hematologic disease (Group 3), children without a CVC (Group 4) and healthy adult controls (Group 5). To evaluate intestinal permeability, we quantified circulating bacterial products LPS and MDP through the binding of their respective receptors, TLR4 and NOD2. To determine colonic inflammation, fecal calprotectin was quantified from a single stool sample. Cytokine profiles included IFN-γ, IL-Iβ, IL-8, IL-10, IL-17, TNFα were quantified by Multiplex Immunoassay while gene expression of transcription factors FoxP3+, RORγT, TLR2, and TLR4, were determined by RNA extraction and quantitative PCR.

Results

22 children were recruited in the study (Group 1 n=6, Group 2 n=6, Group 3 n=5, Group 4 n=5) as well as 10 adult control samples (Group 5). The median age of Group 1 was 67 months with a residual small intestine of 26.5cm (IQR 24.7–40) while those in Group 2 were 51 months with a residual small intestine of 55cm (IQR 31.2–89). Circulating bacterial products of LPS and MDP were not different between SBS groups and control children. Serum analysis of cytokine TNFα was significant (p&lt;0.005) however multiple comparator analysis did not identify within group differences. Other cytokines did not differ between groups. Fecal calprotectin levels were not elevated however statistically lower in Group 1 (median 12.8mg/kg; IQR 9.3- 34.9) compared to in Group 2 (median 96mg/kg, IQR 71.6–188.2;) p &lt;0.01. Relative quantification of RNA expression of FoxP3+, RORγT, TLR2, and TLR4 did not differ between groups.

Conclusions

Despite concern of compromised intestinal epithelial barrier function in children with SBS, this study did not detect differences in circulating bacterial products compared to control children as an assessment of intestinal permeability nor increased systemic inflammation. Further research is required to investigate intestinal epithelial barrier function over time and the mechanism of bacteremia in children with SBS.

Funding Agencies

CAGRegional Medical Associates of Hamilton

A120 INFLUENCE OF THE MICROBIOTA ON THE POSTNATAL DEVELOPMENT OF THE ENTERIC NERVOUS SYSTEM IS DEPENDENT ON MOUSE STRAIN

Background

Gastrointestinal function depends on the normal formation of the enteric nervous system (ENS) during fetal and postnatal development. Prior research in an outbred strain of mice (NIH Swiss) has shown that the absence of the gut microbiome in germ-free (GF) mice results in morphological and functional abnormalities of the ENS compared to specific pathogen free (SPF) mice, including an alteration in proportion of nitrergic neurons. Increasing research has been suggesting that the genetic background of the host can impact the host response to the GF state.

Aims

We tested the hypothesis that the absence of the microbiome in an inbred mouse strain (C57BL/6) could influence the development of the ENS during early postnatal life.

Methods

C57BL/6 GF and SPF mice were sacrificed at postnatal day 3 (P3) and P28 (n=4–5 per group). Ileum and colon were collected at P3 and P28 and processed for whole mount preparations. The neuronal network in the myenteric plexus was visualized by immunohistochemistry using antibodies against the pan-neuronal marker PGP9.5. Neuronal cell bodies and nitrergic neurons were identified by immunolabeling with antibodies to the neuronal marker HuC/D and to neuronal nitric oxide (nNOS). Nerve fibre density was quantified by measuring the percentage of PGP9.5-positive pixels (μm2) compared to the whole field using an image analysis program (Volocity; reported as %). Proportions of nitrergic to myenteric neurons were determined by manually counting (blinded) the number of nNOS-positive neurons and dividing by the total number of HuC/D-positive cells per field (reported as %).

Results

We found a significant increase in nerve density at P3 in the GF compared to SPF mice in both ileum (43% vs. 37%; p=0.03) and colon (45% vs. 39%; p=0.03). No significant differences, however, were identified between GF and SPF mice at P28 in either ileum (27% vs. 25%; n.s.) or colon (31% vs. 32%; n.s.). At P3, no significant differences in proportion of nitrergic neurons were seen in the GF compared to SPF ileum (27% vs. 27%; n.s.).

Conclusions

In contrast to earlier observations in the NIH Swiss mice, in which GF mice had decreased nerve density and an increase in nitrergic neurons at P3, our findings reveal an opposite response in nerve density in the C57BL/6 mice and no change in nitrergic neurons. These results suggest that the genetic strain of the mouse model can influence the host response to changes in the microbiome. Further studies are needed to further elucidate potential underlying mechanisms.

Funding Agencies

NSERC

Associations Between Colonic Motor Patterns and Autonomic Nervous System Activity Assessed by High-Resolution Manometry and Concurrent Heart Rate Variability

Abnormal colonic motility may be associated with dysfunction of the autonomic nervous system (ANS). Our aim was to evaluate if associations between colonic motor patterns and autonomic neural activity could be demonstrated by assessing changes in heart rate variability (HRV) in healthy volunteers. A total of 145 colonic motor patterns were assessed in 11 healthy volunteers by High-Resolution Colonic Manometry (HRCM) using an 84-channel water-perfused catheter. Motor patterns were evoked by balloon distention, a meal and luminal bisacodyl. The electrocardiogram (ECG) and cardiac impedance were assessed during colonic manometry. Respiratory sinus arrhythmia (RSA) and root mean square of successive differences of beat-to-beat intervals (RMSSD) served as measures of parasympathetic reactivity while the Baevsky's Stress Index (SI) and the pre-ejection period (PEP) were used as measures of sympathetic reactivity. Taking all motor patterns into account, our data show that colonic motor patterns are accompanied by increased parasympathetic activity and decreased sympathetic activity that may occur without eliciting a significant change in heart rate. Motor Complexes (more than one motor pattern occurring in close proximity), High-Amplitude Propagating Pressure Waves followed by Simultaneous Pressure Waves (HAPW-SPWs) and HAPWs without SPWs are all associated with an increase in RSA and a decrease in SI. Hence RSA and SI may best reflect autonomic activity in the colon during these motor patterns as compared to RMSSD and PEP. SI and PEP do not measure identical sympathetic reactivity. The SPW, which is a very low amplitude pressure wave, did not significantly change the autonomic measures employed here. In conclusion, colonic motor patterns are associated with activity in the ANS which is reflected in autonomic measures of heart rate variability. These autonomic measures may serve as proxies for autonomic neural dysfunction in patients with colonic dysmotility.

Bioinspired Poly(vinylidene fluoride) Membranes with Directional Release of Therapeutic Essential Oils

Here, the morphology of polypore fungi has inspired the fabrication of poly(vinylidene fluoride) (PVDF) membranes with dual porosity by nonsolvent-induced phase separation (NIPS). The fruiting body of such microorganisms is constituted of two distinct regions, finger- and sponge-like structures, which have been successfully mimicked by controlling the coagulation bath temperature during the NIPS process. The use of water at 10 °C as coagulant resulted in membranes with the highest finger-like/sponge-like ratio (53% of the total membrane thickness), while water at 90 °C allowed the formation of macrovoid-free membranes. The microchannels and the asymmetric porosity were used to enhance the oil sorption capacity of the PVDF membranes and to achieve directional release of therapeutic essential oils. These PVDF membranes with easily tuned asymmetric channel-like porosity and controlled pore size are ideal candidates for drug delivery applications.

Physiological modulation of intestinal motility by enteric dopaminergic neurons and the D2 receptor: analysis of dopamine receptor expression, location, development, and function in wild-type and knock-out mice

Dopaminergic neurons are present in both plexuses of the murine bowel and are upregulated after extrinsic denervation but play unknown roles in enteric nervous system (ENS) physiology. Transcripts encoding dopamine (DA) receptors D1-D5 were analyzed by reverse transcription-PCR in stomach approximately duodenum approximately ileum approximately proximal > > distal colon. Dissected muscle and myenteric plexus contained transcripts encoding D1-D3 and D5, whereas mucosa contained D1 and D3-D5. D1-D5 expression began in fetal gut [embryonic day 10 (E10)], before the appearance of neurons (E12), and was sustained without developmental regulation through postnatal day 1. In situ hybridization revealed that subsets of submucosal and myenteric neurons contained mRNA encoding D2 or D3. Immunoblots confirmed that D1, D2, and D5 receptor proteins were present from stomach through distal colon. Subsets of submucosal and myenteric neurons were also D1, D2, or D3 immunoreactive. When double labeled by in situ hybridization, these neurons contained mRNA encoding the respective receptors. Total gastrointestinal transit time (TGTT) and colonic transit time (CTT) were measured in mice lacking D2, D3, or D2 plus D3. Both TGTT and CTT were decreased significantly (motility increased) in D2 and D2 plus D3, but not D3, knock-out animals. Mice lacking D2 and D2 plus D3 but not D3 were smaller than wild-type littermates, yet ate significantly more and had greater stool frequency, water content, and mass. Because motility is abnormal when D2 is absent, the net inhibitory DA effect on motility is physiologically significant. The early expression of DA receptors is also consistent with the possibility that DA affects ENS development.

A role for complement in the rejection of porcine ventral mesencephalic xenografts in a rat model of Parkinson's disease

Vascularized whole organ discordant xenografts placed in the periphery are rejected by a rapid "hyperacute" process that involves preformed antibody binding to the xeno-antigens on the donor endothelial cells with complement activation. In the CNS, xenografts are classically thought to be rejected more slowly by a T-cell-dependent process. We now report that xenografts of embryonic porcine ventral mesencephalic tissue in the 6-hydroxydopamine-lesioned, nonimmunosuppressed rat induce both a humoral and a cell-mediated response. Over the first 10 d after implantation, the xenografts matured with identifiable TH neurons and pig-specific neurofilament fibers extending along host white matter tracts. During this period of time, IgM and complement binding were observed within the graft, as well as a CD8 cellular infiltrate, leading to rejection of the transplant over the next 25 d. These intracerebral xenografts were not associated with an early systemic antibody response. A role for complement in this rejection process was further investigated using cobra venom factor (CVF), which systemically depleted the rats of complement for 7 d. CVF treatment, when given in the period immediately before and after grafting, delayed but did not prevent the cellular immune response induced by the graft, demonstrating that xenografted neural tissue can activate the humoral arm of the rejection process, in particular the complement cascade. This suggests that interventions targeting this aspect of the immune rejection process may be of great importance for the future development of xenotransplantation for neurodegenerative conditions.

Fetal porcine dopaminergic cell survival in vitro and its relationship to embryonic age

One of the critical factors in the survival of embryonic neural grafts is the age at which the population of donor neurons is harvested. This is especially the case for the developing dopaminergic neurons in the embryonic ventral mesencephalon, which are used for neural grafts in Parkinson's disease (PD). The donor age for optimal harvesting of these cells has been well characterized in the mouse, rat, and marmoset, and to a lesser extent in humans. However, the best donor age for porcine ventral mesencephalic tissue has not been ascertained, even though the use of this tissue for xenografts has been explored both experimentally and clinically. In this study the effect of donor age on dopaminergic cell survival was assessed in vitro, from a range of fetal pigs aged from E24 to E35. The number of tyrosine hydroxylase (TH)-positive cells per ventral mesencephalon was then calculated after 1 and 7 days in culture. E26-E27 embryos gave the highest yield of such cells at both survival time points, suggesting that this will be the optimal age for harvesting tissues whether for experimental or clinical nigral xenograft programs.

Differential activities of protein phosphatase types 1 and 2A in cytosolic and particulate fractions from rat forebrain

The activities and concentrations of protein phosphatase type 1 (PP1) and type 2A (PP2A) were compared in cytosol and particulate fractions of rat forebrain. Although the activity of PP2A was highest in the cytosol, immunoblot analysis with a PP2A-specific antibody showed that there were significant levels of the enzyme in the particulate fraction. There was no significant difference between the concentration of PP2A in the cytosol and particulate fractions such that the low activity of PP2A in the particulate fraction represents an inactivation of this form of the enzyme. Similar analysis in skeletal muscle, heart, and liver showed this finding was unique to the brain. Similarly, the majority of PP1 activity was recovered in the cytosol, but most PP1 enzyme was associated with the particulate fraction. Comparison with other tissues showed that the activities of PP1 in the particulate fractions were similar but that the forebrain contained significantly more enzyme than the other tissues. Thus, like PP2A it appears that the specific activity of PP1 in the particulate fraction of rat forebrain is much lower than that of the cytosol and of the particulate fractions of other tissues. Elution of PP1 and PP2A from membranes with 0.5 M NaCl plus 0.3% Triton X-100 resulted in severalfold activation of both enzymes. That the majority of PP1 and PP2A in rat forebrain are associated with membrane structures but in a low activity state suggests that novel regulatory mechanisms exist that have considerable and unique potential for activation of protein dephosphorylation.