Peripheral Pathways Research Articles

Anatomy of Trigeminal Neuromodulation Targets: From Periphery to the Brain.

The trigeminal nerve complex is a very important and somewhat unique component of the nervous system. It is responsible for the sensory signals that arise from the most part of the face, mouth, nose, meninges, and facial muscles, and also for the motor commands carried to the masticatory muscles. These signals travel through a very complex set of structures: dermal receptors, trigeminal branches, Gasserian ganglion, central nuclei, and thalamus, finally reaching the cerebral cortex. Other neural structures participate, directly or indirectly, in the transmission and modulation of the signals, especially the nociceptive ones; these include vagus nerve, sphenopalatine ganglion, occipital nerves, cervical spinal cord, periaqueductal gray matter, hypothalamus, and motor cortex. But not all stimuli transmitted through the trigeminal system are perceivable. There is a constant selection and modulation of the signals, with either suppression or potentiation of the impulses. As a result, either normal sensory perceptions are elicited or erratic painful sensations are created. Electrical neuromodulation refers to adjustable manipulation of the central or peripheral pain pathways using electrical current for the purpose of reversible modification of the function of the nociceptive system through the use of implantable devices. Here, we discuss not only the distal components, the nerve itself, but also the sensory receptors and the main central connections of the brain, paying attention to the possible neuromodulation targets.

Neuromodulation for Refractory Angina, Heart Failure and Peripheral Vascular Disease

Use of spinal cord stimulation (SCS) has expanded beyond pain control. There are increasing indications in which SCS is being used. The understanding of central and peripheral neural pathways and their controlling influences on peripheral organs is better understood now. The concept of stimulating the spinal cord and modulating central pathways with SCS is already established. Different studies have shown the benefit with SCS on visceral pain control, improving quality of live in severe peripheral vascular disease and even assist in controlling the vago-sympathetic balance. We will discuss the art of implantation. Patient selection and stimulation with respect to current clinical data.

Pyomelanin biosynthetic pathway in pigment-producer strains from the pandemic Acinetobacter baumannii IC-5.

BACKGROUND Acinetobacter baumannii outbreaks have been associated with pandemic International Clones (ICs), but the virulence factors involved with their pathogenicity are sparsely understood. Pigment production has been linked with bacterial pathogenicity, however, this phenotype is rarely observed in A. baumannii.OBJECTIVES This study aimed to characterise the reddish-brown pigment produced by A. baumannii strains, and to determine its biosynthetic pathway by genomic approaches.METHODS Pigment characterisation and antimicrobial susceptibility were conducted by phenotypic tests. The clonal relationship was obtained by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The genome of an A. baumannii was obtained for characterisation of genes involved with pigment production.FINDINGS The pyomelanin was the pigment produced by A. baumannii. Strains were extensively drug resistant and belonged to the IC-5/ST79. The pyomelanin biosynthetic pathway was determined and presented a particular architecture concerning the peripheral (tyrB, phhB and hpd) and central (hmgB, hmgC and hmgR) metabolic pathway genes. The identification of a distant HmgA homologue, probably without dioxygenase activity, could explain pyomelanin production. Virulence determinants involved with adherence (csuA/BABCDE and a T5bSS-carrying genomic island), and iron uptake (basABCDEFGHIJ, bauABCDEF and barAB) were characterised.MAIN CONCLUSION There is a biosynthetic pathway compatible with the pyomelanin production observed in persistent A. baumannii IC-5 strains.

Audiological and electrophysiological assessment of professional orchestral musicians

ABSTRACT Purpose: to verify whether the frequent musical exposure can impair peripheral and central auditory pathway responses in professional orchestral musicians. Methods: 45 male individuals from 19 to 40 years old participated in the study. They were divided into two groups: one comprising 30 orchestral musicians who played strings or wind instruments, and another with 15 nonmusicians. The two groups were submitted to both conventional and high-frequency pure-tone audiometry, transient-evoked otoacoustic emissions, and frequency-following response. The results were subjected to descriptive and inferential statistical analysis, using the one-way ANOVA unmatched samples parametric test, with a 5% significance level. Results: no significant differences were observed between the hearing thresholds in both conventional and high-frequency audiometry and frequency-following response. However, there were statistically significant differences between transient-evoked otoacoustic emission responses, with lower responses to musicians in comparison to the nonmusician group. Conclusion: the results suggest that frequent musical exposure experienced by orchestral musicians can impair the cochlear hair cells’ function. Therefore, audiological monitoring is important to detect subclinical impairments.

Duloxetine reverses the symptoms of overactive bladder co-existing with depression via the central pathways

Though the association between overactive bladder (OAB) and depression was noticed years ago, the pharmaceutical market does not offer one universal drug that would cure both conditions at the same time. The main goal of our present experiments was to determine whether a 14-day administration of solifenacin (0.03 mg/kg/day), mirabegron (1 mg/kg/day), or duloxetine (1 mg/kg/day) would reverse detrusor overactivity and depression-like signs in female Wistar rats subjected to corticosterone treatment. Surgical procedures, cystometric studies, biochemical analyses, and the forced swim test were performed according to published literature. After 14 days of exposure to corticosterone (20 mg/kg/day, subcutaneously), the tested animals presented symptoms of depression, detrusor overactivity, inflammation, and disturbances in neurotrophic factors. The obtained results demonstrated that solifenacin and mirabegron act mainly via peripheral pathways in OAB, whereas the central pathways are responsible for the effects of duloxetine. 72 h after discontinuation of duloxetine treatment, positive changes in the corticosterone-induced depression, detrusor overactivity, and inflammation were observed. Duloxetine seems to have a potential to become a new treatment option for patients with OAB co-existing with depression.

Total sleep deprivation increases pain sensitivity, impairs conditioned pain modulation and facilitates temporal summation of pain in healthy participants.

Chronic pain patients often suffer from insomnia or impaired sleep which has been associated with increased pain sensitivity, but a limited amount of studies have investigated the effects of total sleep deprivation on central pain mechanisms. Therefore, the aim of this study was to determine the effects of total sleep deprivation on temporal summation, conditioned pain modulation, thermal and pressure pain sensitivity in healthy participants. Twenty-four healthy participants took part in this two-session trial. The measurements were conducted after a night of habitual sleep (baseline) and following 24 hours of total sleep deprivation. Detection thresholds for cold and warmth and pain thresholds for cold and heat were assessed. Cuff induced pressure pain detection and tolerance thresholds, temporal summation and conditioned pain modulation were assessed with user-independent, computer-controlled cuff algometry. Conditioned pain modulation was significantly impaired, temporal summation was significantly facilitated and pain sensitivity to pressure and cold pain were significantly increased at follow-up compared with baseline. In conclusion, this study found that one night of total sleep deprivation impaired descending pain pathways, facilitated spinal excitability and sensitized peripheral pathways to cold and pressure pain. Future studies are encouraged to investigate if sleep therapy might normalize pain sensitivity in sleep-deprived chronic pain patients.

P.009 The peripheral serotonin pathway in major depression before and after antidepressant treatment: a case-control prospective study

P.009 The peripheral serotonin pathway in major depression before and after antidepressant treatment: a case-control prospective study

Optimal Criteria for the Selection of Probiotics, Based on their Mode of Action

Abstract The objective of this review was to discuss some of the criteria which influence the selection of microorganisms with probiotic properties based on their mode of action. The most common bacteria that belong to the “group” probiotics are the Lactobacillus and Bifidobacterium species/strains. Probiotics have benefits and effects by their mechanism of action in different axial locations such as: producing substances, influencing immune function and response, modification as well as maintenance of a healthy population of microorganisms in the intestinal environment. Probiotics have demonstrated significant potential as therapeutic options for a variety of diseases Potential peripheral pathways that link probiotic ingestion in the brain function are focused on the role of the vagal afferent nerve signalling and changes in the cerebral levels of neuromodulators. The application of probiotic microorganisms represents a way to effectively influence the composition of the intestinal microbiome and the immune system of the host, as well as they can be considered as a suitable alternative to influence a healthy quality of life.

Exploring the genetic potential of a fosmid metagenomic library from an oil-impacted mangrove sediment for metabolism of aromatic compounds.

Aromatic hydrocarbons (AH) are widely distributed in nature, and many of them have been reported as relevant environmental pollutants and valuable carbon sources for different microorganisms. In this work, high-throughput sequencing of a metagenomic fosmid library was carried out to evaluate the functional and taxonomic diversity of genes involved in aromatic compounds degradation in oil-impacted mangrove sediments. In addition, activity-based approach and gas chromatography were used to assess the degradation potential of fosmid clones. Results indicated that AH degradation genes, such as monooxygenases and dioxygenases, were grouped into the following categories: anaerobic degradation of aromatic compounds (20.34%), metabolism of central aromatic intermediates (35.40%) and peripheral pathways for catabolism of aromatic compounds (22.56%). Taxonomic affiliation of genes related to aromatic compounds metabolism revealed the prevalence of the classes Alphaproteobacteria, Actinobacteria, Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria. Aromatic hydrocarbons (phenol, naphthalene, phenanthrene, pyrene and benzopyrene) were used as the only carbon source to screen clones with degradation potential. Of the 2500 clones tested, 48 showed some respiratory activity in at least one of the five carbon sources used. The hydrocarbon degradation ability of the top ten fosmid clones was confirmed by GC-MS. Further, annotation of assembled metagenomic fragments revealed ORFs corresponding to proteins and functional domains directly or indirectly involved in the aromatic compound metabolism, such as catechol 2,3-dioxygenase and ferredoxin oxidoreductase. Finally, these data suggest that the indigenous mangrove sediment microbiota developed essential mechanisms towards ecosystem remediation of petroleum hydrocarbon impact.

Crotoxin Conjugated to SBA-15 Nanostructured Mesoporous Silica Induces Long-Last Analgesic Effect in the Neuropathic Pain Model in Mice.

Neuropathic pain is a disease caused by structural and functional plasticity in central and peripheral sensory pathways that produce alterations in nociceptive processing. Currently, pharmacological treatment for this condition remains a challenge. Crotoxin (CTX), the main neurotoxin of Crotalus durissus terrificus rattlesnake venom, has well described prolonged anti-inflammatory and antinociceptive activities. In spite of its potential benefits, the toxicity of CTX remains a limiting factor for its use. SBA-15 is an inert nanostructured mesoporous silica that, when used as a vehicle, may reduce toxicity and potentiate the activity of different compounds. Based on this, we propose to conjugate crotoxin with SBA-15 (CTX:SBA-15) in order to investigate if when adsorbed to silica, CTX would have its toxicity reduced and its analgesic effect enhanced in neuropathic pain induced by the partial sciatic nerve ligation (PSNL) model. SBA-15 enabled an increase of 35% of CTX dosage. Treatment with CTX:SBA-15 induced a long-lasting reduction of mechanical hypernociception, without modifying the previously known pathways involved in antinociception. Moreover, CTX:SBA-15 reduced IL-6 and increased IL-10 levels in the spinal cord. Surprisingly, the antinociceptive effect of CTX:SBA-15 was also observed after oral administration. These data indicate the potential use of the CTX:SBA-15 complex for neuropathic pain control and corroborates the protective potential of SBA-15.

Role of the immune system in neuropathic pain.

Background Acute pain is a warning mechanism that exists to prevent tissue damage, however pain can outlast its protective purpose and persist beyond injury, becoming chronic. Chronic Pain is maladaptive and needs addressing as available medicines are only partially effective and cause severe side effects. There are profound differences between acute and chronic pain. Dramatic changes occur in both peripheral and central pathways resulting in the pain system being sensitised, thereby leading to exaggerated responses to noxious stimuli (hyperalgesia) and responses to non-noxious stimuli (allodynia). Critical role for immune system cells in chronic pain Preclinical models of neuropathic pain provide evidence for a critical mechanistic role for immune cells in the chronicity of pain. Importantly, human imaging studies are consistent with preclinical findings, with glial activation evident in the brain of patients experiencing chronic pain. Indeed, immune cells are no longer considered to be passive bystanders in the nervous system; a consensus is emerging that, through their communication with neurons, they can both propagate and maintain disease states, including neuropathic pain. The focus of this review is on the plastic changes that occur under neuropathic pain conditions at the site of nerve injury, the dorsal root ganglia (DRG) and the dorsal horn of the spinal cord. At these sites both endothelial damage and increased neuronal activity result in recruitment of monocytes/macrophages (peripherally) and activation of microglia (centrally), which release mediators that lead to sensitisation of neurons thereby enabling positive feedback that sustains chronic pain. Immune system reactions to peripheral nerve injuries At the site of peripheral nerve injury following chemotherapy treatment for cancer for example, the occurrence of endothelial activation results in recruitment of CX3C chemokine receptor 1 (CX3CR1)-expressing monocytes/macrophages, which sensitise nociceptive neurons through the release of reactive oxygen species (ROS) that activate transient receptor potential ankyrin 1 (TRPA1) channels to evoke a pain response. In the DRG, neuro-immune cross talk following peripheral nerve injury is accomplished through the release of extracellular vesicles by neurons, which are engulfed by nearby macrophages. These vesicles deliver several determinants including microRNAs (miRs), with the potential to afford long-term alterations in macrophages that impact pain mechanisms. On one hand the delivery of neuron-derived miR-21 to macrophages for example, polarises these cells towards a pro-inflammatory/pro-nociceptive phenotype; on the other hand, silencing miR-21 expression in sensory neurons prevents both development of neuropathic allodynia and recruitment of macrophages in the DRG. Immune system mechanisms in the central nervous system In the dorsal horn of the spinal cord, growing evidence over the last two decades has delineated signalling pathways that mediate neuron-microglia communication such as P2X4/BDNF/GABAA, P2X7/Cathepsin S/Fractalkine/CX3CR1, and CSF-1/CSF-1R/DAP12 pathway-dependent mechanisms. Conclusions and implications Definition of the modalities by which neuron and immune cells communicate at different locations of the pain pathway under neuropathic pain states constitutes innovative biology that takes the pain field in a different direction and provides opportunities for novel approaches for the treatment of chronic pain.

Effects of genotype on TENS effectiveness in controlling knee pain in persons with mild to moderate osteoarthritis.

This study examined the extent to which genetic variability modifies Transcutaneous Electrical Nerve Stimulation (TENS) effectiveness in osteoarthritic knee pain. Seventy-five participants with knee osteoarthritis were randomly assigned to either: (a) High-frequency TENS, (b) Low-frequency TENS or (c) Transient Placebo TENS. Pain measures were collected pre- and post-treatment. Participants were genotyped on genes implicated in central or peripheral pain pathways: NGFB, NTRK1, EDNRA, EDNRB, EDN1, OPRM1, TAC1, TACR1, BDNF, BDKRB1, 5HTT, COMT, ESR2, IL6 and IL1B. Genetic association using linear regression modelling was performed separately for the transient placebo TENS subjects, and within the High-frequency TENS+Low-frequency TENS participants, including TENS level as a covariate. In the placebo group, SNPs rs165599 (COMT) was significantly associated with an increased heat pain threshold (β=-1.87; p=.003) and rs6827096 (EDNRA) with an increased resting pain (β=2.68; p=.001). Within the treatment groups, TENS effectiveness was reduced by the SNP rs6537485 (EDNRA) minor allele in relationship to mechanical sensation (β=184.13; p=5.5E-9). Individuals with the COMT rs4680 minor allele reported lowered pain at rest after TENS (β=-42.30; p=.001), with a higher magnitude of pain reduction (28 unit difference) in the low-frequency TENS group compared to the high-frequency TENS group (β=28.37; p=.0004). EDNRA and COMT are implicated in osteoarthritic knee pain and provide a basis for tailoring TENS interventions according to individual characteristics. Findings from this study demonstrate that genetic variation within the COMT and EDNRA genes influences the effectiveness of TENS, a non-pharmacologic pain-reduction intervention, in the context of osteoarthritic knee pain. Evidence such as this may contribute to risk models that provide a clinically useful tool for personalizing TENS interventions according to individual characteristics in order to best control pain and maximize functional status.

Analgesic properties of the ethanol extract of leaves of <i>Triumfetta cordifolia</i> A. Rich

Triumfetta cordifolia is used ethnomedicinally in the management of pain, inflammatory and mental disorders. No study has been carried out to scientifically confirm its ethnomedicinal use in the management of pain. Hence, this study was design to evaluate the antinociceptive property of ethanol extract of leaves of T. cordifolia (EETC) in experimental models of pain in mice. The antinociceptive property of EETC (8.8, 17.5 and 35 mg/kg) administered intraperitoneally (i.p.) was assessed on acetic acid-induced abdominal writhing, formalin-induced paw licking, hot water tail immersion and hot plate-induced nociception tests. In addition, naloxone (1 mg/kg, i.p.) was used to elucidate the involvement of opioidergic system in the antinociceptive activity of EETC in hot plate test. EETC (8.8, 17.5 and 35 mg/kg, i.p.) significantly (p < 0.05) reduced acetic acid-induced writhing when compared with control. Also, EETC (8.8, 17.5 and 35 mg/kg, i.p.) dose-dependently attenuated formalin-induced paw licking; as it significantly (p < 0.05) inhibited the inflammatory phase, although only EETC (35 mg/kg, i.p.) was found to suppressed the neurogenic phase. Moreover, EETC significantly (p < 0.05) increased the reaction time to pain in mice exposed to hot plate test, with no significant effect in the hot water tail immersion test when compared with control. Naloxone significantly (p < 0.05) reversed the effect of EETC on hot plate-induced pain. In conclusion, the results of this study provide evidence, showing that EETC possesses phytochemical compounds with analgesic activity and may be related to peripheral nociception mediation and central opioidergic pain pathway system. Keywords: Triumfetta cordifolia; Analgesia; Writhing; Paw-licking

The rat as a model for studying noise injury and otoprotection.

A major challenge for those studying noise-induced injury pre-clinically is the selection of an animal model. Noise injury models are particularly relevant in an age when people are constantly bombarded by loud noise due to occupation and/or recreation. The rat has been widely used for noise-related morphological, physiological, biochemical, and molecular assessment. Noise exposure resulting in a temporary (TTS) or permanent threshold shift (PTS) yields trauma in peripheral and central auditory related pathways. While the precise nature of noise-related injuries continues to be delineated, both PTS and TTS (with or without hidden hearing loss) result in homeostatic changes implicated in conditions such as tinnitus and hyperacusis. Compared to mice, rats generally tolerate exposure to loud sounds reasonably well, often without exhibiting other physical non-inner ear related symptoms such as death, loss of consciousness, or seizures [Skradski, Clark, Jiang, White, Fu, and Ptacek (2001). Neuron 31, 537-544; Faingold (2002). Hear. Res. 168, 223-237; Firstova, Abaimov, Surina, Poletaeva, Fedotova, and Kovalev (2012). Bull Exp. Biol. Med. 154, 196-198; De Sarro, Russo, Citraro, and Meldrum (2017). Epilepsy Behav. 71, 165-173]. This ability of the rat to thrive following noise exposure permits study of long-term effects. Like the mouse, the rat also offers a well-characterized genome allowing genetic manipulations (i.e., knock-out, viral-based gene expression modulation, and optogenetics). Rat models of noise-related injury also provide valuable information for understanding mechanistic changes to identify therapeutic targets for treatment. This article provides a framework for selection of the rat as a model for noise injury studies.

Contribution of Baroreflex Afferent Pathway to NPY-Mediated Regulation of Blood Pressure in Rats.

Neuropeptide Y (NPY), a metabolism-related cardiovascular factor, plays a crucial role in blood pressure (BP) regulation via peripheral and central pathways. The expression of NPY receptors (Y1R/Y2R) specific to baroreflex afferents impacts on the sexually dimorphic neural control of circulation. This study was designed to investigate the expression profiles of NPY receptors in the nodose ganglion (NG) and nucleus tractus solitary (NTS) under hypertensive conditions. To this end, rats with hypertension induced by NG-nitro-L-arginine methylester (L-NAME) or high fructose drinking (HFD), and spontaneously hypertensive rats (SHRs) were used to explore the effects/mechanisms of NPY on BP using functional, molecular, and electrophysiological approaches. The data showed that BP was elevated along with baroreceptor sensitivity dysfunction in model rats; Y1R was up- or down-regulated in the NG or NTS of male and female HFD/L-NAME groups, while Y2R was only down-regulated in the HFD groups as well as in the NG of the male L-NAME group. In SHRs, Y1R and Y2R were both down-regulated in the NTS, and not in the NG. In addition to NPY-mediated energy homeostasis, leptin-melanocortin activation may be essential for metabolic disturbance-related hypertension. We found that leptin and α-melanocyte stimulating hormone (α-MSH) receptors were aberrantly down-regulated in HFD rats. In addition, α-MSH concentrations were reduced and NPY concentrations were elevated in the serum and NTS at 60 and 90min after acute leptin infusion. Electrophysiological recordings showed that the decay time-constant and area under the curve of excitatory post-synaptic currents were decreased by Y1R activation in A-types, whereas, both were increased by Y2R activation in Ah- or C-types. These results demonstrate that sex- and afferent-specific NPY receptor expression in the baroreflex afferent pathway is likely to be a novel target for the clinical management of metabolism-related and essential hypertension.

Early intervention with breast milk mesenchymal stem cells attenuates the development of diabetic-induced testicular dysfunction via hypothalamic Kisspeptin/Kiss1r-GnRH/GnIH system in male rats

Diabetic male infertility and sub fertility are major complications that may implicate both central and peripheral pathways as well as mechanisms controlling reproduction. This study was an attempt to explore the potential effect of breast milk mesenchymal stem cells (Br-MSCs) as a therapeutic tool for diabetic induced reproductive dysfunction at molecular level. Forty-five adult male Sprague Dawely rats were divided into 3 groups (n = 15); control group, diabetic group, and Br-MSCs treated diabetic group. The homing ability of Br-MSCs in diabetic treated rat testicles was confirmed via semi-quantitative RT- PCR analysis of a human specific Gapdh mRNA expression level. Our result showed that type1 diabetic rats exerted an elevation in blood glucose level and a reduction in body weight, fasting serum insulin, FSH, LH, and total testosterone levels, relative and absolute testicular weights, sperm count, motility, and live ratio. In addition, downregulation in the hypothalamic kisspeptin-GnRH system, HPG axis and testicular steroidogenesis compared to control group was noticed. Moreover, upregulation of testicular proinflammatory and apoptotic markers relative mRNA expression compared to control group was observed. Furthermore, a decrease in testicular tissue antioxidant activity (CAT, SOD, GSH) and an increase in lipid peroxidation (MDA) compared to control group was shown. However, Br-MSCs administration restored or even exceeded the normal physiological tone in most of these parameters to the point where a potential therapeutic role for Br-MSCs in type1diabetic induced infertility can be suggested.

Spotlight in Plastic Surgery: October 2019

Spotlight in Plastic Surgery: October 2019

PGE2/EP4 receptor and TRPV1 channel are involved in repeated restraint stress-induced prolongation of sensitization pain evoked by subsequent PGE2 challenge

Prevalence of prior stressful experience is linked to high incidence of chronic pain. Stress, particularly repeated stress, is known to induce maladaptive neuroplasticity along peripheral and central pain transmission pathways. These maladaptive neuroplastic events facilitate sensitization of nociceptive neurons and transition from acute to chronic pain. Pro-inflammatory and pain mediators are involved in inducing neuroplasticity. Pain mediators such as prostaglandin E2 (PGE2), EP4 receptor and transient receptor potential vanilloid-1 (TRPV1) contributes to the genesis of chronic pain. In this study, we examined role of PGE2/EP4 signaling and TRPV1 signaling in repeated restraint stress-induced prolongation of sensitization pain, a model for transition from acute to chronic pain, in both in vivo and in vitro models. We found that pre-exposure to single restraint stress induced analgesia that masked sensitization pain evoked by subsequent PGE2 challenge. However, pre-exposure to 3d consecutive restraint stress not only prolonged sensitization pain, but also increased stress hormone corticosterone (CORT) in serum, COX2 levels in paw skin, EP4 and TRPV1 levels in dorsal root ganglion (DRG) and paw skin. Pre-exposure to CORT for 3d, not 1d, also prolonged sensitization pain evoked by PGE2. Co-injection of glucocorticoid receptor (GR) antagonist RU486, COX2 inhibitor NS-398, EP4 receptor antagonist L161, 982 or TRPV1 antagonist capsazepine prevented 3d restraint stress prolonged sensitization pain evoked by PGE2. In DRG cultures, CORT increased EP4 and TRPV1 protein levels through GR activation. These data suggest that PGE2/EP4 signaling and TRPV1 signaling in peripheral pain pathway contributes to repeated stress-predisposed transition from acute to chronic pain.

1830 Granular Cell Tumor as a Rare Cause of Dysphagia

INTRODUCTION: Granular cell tumors are a rare cause of dysphagia and dyspepsia. While rare and difficult to detect, diagnosis and resection of GCTs can often provide symptomatic relief in patients. We present a case of a patient with chronic dyspepsia and dysphagia, with a seemingly incidental finding of an esophageal granular cell tumor. CASE DESCRIPTION/METHODS: Patient was a 32-year-old female with a past medical history significant for SLE-Sjogren’s overlap syndrome who presented to the GI clinic for a follow-up appointment with new complaint of dysphagia for two weeks. Patient was evaluated one year prior with complaints of nausea, vomiting, and dyspepsia which was managed with levbid and amitripyline; however, she continued to have symptoms of epigastric abdominal pain. Physical exam was unremarkable. Given continued epigastric abdominal pain and now dysphagia, PPI was increased to twice daily. Repeat EGD showed a nodule in the esophagus, and pathology was consistent with granular cell tumor (GCT) (Figure 1). Patient underwent endoscopic ultrasound (EUS) which showed a sub epithelial 7x3mm hypoechoic nodule in upper third of esophagus within the luminal interface/superficial mucosa and deep mucosa (Figure 2). Patient underwent endoscopic mucosal resection (EMR) of the nodule one month later. On histological evaluation, the resection appeared complete, but there was one margin with tumor extending to the margin, so there was a plan for the patient to repeat EUS/EGD in six months. At six month follow-up, her dysphagia had resolved and her functional abdominal pain had improved enough to allow decreasing her medication requirements. DISCUSSION: Thought to originate from Schwann cells, GCTs are extremely rare tumors that can occur at any anatomical location. Nestin expression in GCTs indicates that they may arise from a common stem cell in the GI tract, which can differentiate along both interstitial cells of Cajal and peripheral nerve pathways, leading to the common abdominal symptoms of abdominal pain, distention, and dysphagia. Decision for removal is determined based on size, with those less than 1 cm in diameter usually being treated conservatively, and those greater than 1cm typically removed, regardless of symptoms, due to increased incidence of malignancy. Our case highlights that GCTs are a rare cause of non-specific abdominal symptoms and of dysphagia but should be considered in all middle aged patients presenting with these symptoms.

Molecular Basis of Cancer Pain Management: An Updated Review.

Pain can have a significantly negative impact on the quality of life of patients. Therefore, patients may resort to analgesics to relieve the pain. The struggle to manage pain in cancer patients effectively and safely has long been an issue in medicine. Analgesics are the mainstay treatment for pain management as they act through various methods on the peripheral and central pain pathways. However, the variability in the patient genotypes may influence a drug response and adverse drug effects that follow through. This review summarizes the observed effects of analgesics on UDP-glucuronosyl (UGT) 2B7 isoenzyme, cytochrome P450 (CYP) 2D6, μ-opioid receptor μ 1 (OPRM1), efflux transporter P-glycoprotein (P-gp) and ATP-binding cassette B1 ABCB1/multiple drug resistance 1 (MDR1) polymorphisms on the mechanism of action of these drugs in managing pain in cancer. Furthermore, this review article also discusses the responses and adverse effects caused by analgesic drugs in cancer pain management, due to the inter-individual variability in their genomes.