Magnesium and Esophageal Pain After Peroral Endoscopic Myotomy of the Esophagus: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Postoperative esophageal pain occurs in 67% of patients after peroral endoscopic esophageal myotomy (POEM). Magnesium can act as a smooth muscle relaxant. This study investigated whether intraoperative magnesium can reduce postoperative esophageal pain in patients undergoing POEM. METHODS: In this double-blind, placebo-controlled trial, 92 patients were randomized to receive either magnesium sulfate as a 50 mg.kg-1 (total body weight) bolus followed by an infusion at 25 mg.kg-1.hr-1, or 0.9% saline. Intraoperative analgesia was standardized in all patients. The primary outcome was the score from a validated, modified Esophageal Symptoms Questionnaire (ESQ) in the postanesthesia care unit (PACU). Pain scores, opioid requirements, and questionnaire scores were collected through postoperative day 1. RESULTS: ESQ scores were significantly lower in the magnesium group in the PACU (median [25th-75th], 24 [18-31] vs 35 [28-42]; median difference [95% confidence interval, CI], 10 [6-13]; P < .0001) and on postoperative day 1 (16 [14-23] vs 30 [24-35]; P < .0001). Less opioids were needed in the magnesium group in the PACU (mean ± standard deviation [SD] [99% CI], 4.7 ± 10 [1-9] mg vs 29 ± 21 [21-37] mg; P < .0001) and on postoperative day 1 (1 ± 3.7 [0-2.5] mg vs 13 ± 23 [4-23] mg; P = .0009). Pain scores were lower in the magnesium group in the PACU (0 [0-3] vs 5 [5-7]; P < .0001) and on postoperative day 1 (0 [0-2] vs 4 [3-5]; P < .0001). CONCLUSIONS: Patients undergoing POEM randomized to receive intraoperative magnesium had sustained reductions in esophageal discomfort severity and opioid requirements 24 hours after surgery.

Impact of BRCA Mutation Status on Tumor Dissemination Pattern, Surgical Outcome and Patient Survival in Primary and Recurrent High-Grade Serous Ovarian Cancer: A Multicenter Retrospective Study by the Ovarian Cancer Therapy-Innovative Models Prolong Survival (OCTIPS) Consortium.

BACKGROUND: This study seeks to evaluate the impact of breast cancer (BRCA) gene status on tumor dissemination pattern, surgical outcome and survival in a multicenter cohort of paired primary ovarian cancer (pOC) and recurrent ovarian cancer (rOC). PATIENTS AND METHODS: Medical records and follow-up data from 190 patients were gathered retrospectively. All patients had surgery at pOC and at least one further rOC surgery at four European high-volume centers. Patients were divided into one cohort with confirmed mutation for BRCA1 and/or BRCA2 (BRCAmut) and a second cohort with BRCA wild type or unknown (BRCAwt). Patterns of tumor presentation, surgical outcome and survival data were analyzed between the two groups. RESULTS: Patients with BRCAmut disease were on average 4 years younger and had significantly more tumor involvement upon diagnosis. Patients with BRCAmut disease showed higher debulking rates at all stages. Multivariate analysis showed that only patient age had significant predictive value for complete tumor resection in pOC. At rOC, however, only BRCAmut status significantly correlated with optimal debulking. Patients with BRCAmut disease showed significantly prolonged overall survival (OS) by 24.3 months. Progression-free survival (PFS) was prolonged in the BRCAmut group at all stages as well, reaching statistical significance during recurrence. CONCLUSIONS: Patients with BRCAmut disease showed a more aggressive course of disease with earlier onset and more extensive tumor dissemination at pOC. However, surgical outcome and OS were significantly better in patients with BRCAmut disease compared with patients with BRCAwt disease. We therefore propose to consider BRCAmut status in regard to patient selection for cytoreductive surgery, especially in rOC.

Prospective randomized comparison of endoscopist-facilitated endotracheal intubation and standard intubation for ERCP.

BACKGROUND AND AIMS: Complex endoscopic procedures are increasingly performed with anesthesia support, which substantially affects endoscopy unit efficiency. ERCP performed with the patient under general anesthesia presents unique challenges, as patients are typically first intubated, then transferred to the fluoroscopy table and positioned semi-prone. This requires additional time and staff while increasing the potential for patient/staff injury. We have developed the technique of endoscopist-facilitated intubation using an endotracheal tube backloaded onto an ultra-slim gastroscope as a potential solution to these issues and evaluated its utility prospectively. METHODS: Sequential patients undergoing ERCP were randomized to undergo endoscopist-facilitated intubation or to standard intubation. Demographic data, patient/procedure characteristics, endoscopy efficiency parameters, and adverse events were analyzed. RESULTS: During the study period, 45 ERCP patients were randomized to undergo either endoscopist-facilitated intubation (n = 23) or standard intubation (n = 22). Endoscopist-facilitated intubation was successful in all patients, with no hypoxic events. Median time from patient arrival in room to procedural start was shorter in patients undergoing endoscopist-facilitated intubation versus standard intubation (8.2 vs 29 minutes, P < .0001). Endoscopist-facilitated intubations were brisker than standard intubations (.63 vs 2.85 minutes, P < .0001). Patients undergoing endoscopist-facilitated intubation reported less postprocedure throat discomfort (13% vs 50%, P < .01) and fewer myalgia incidences (22% vs 73%, P < .01) than patients undergoing standard intubation. CONCLUSIONS: Endoscopist-facilitated intubation was technically successful in every patient. Median endoscopist-facilitated intubation time from patient arrival in room to procedural start was 3.5-fold lower, and median endoscopist-facilitated intubation time was >4-fold lower, than for standard intubation. Endoscopist-facilitated intubation significantly enhanced endoscopy unit efficiency and minimized staff and patient injury. General adoption of this novel approach may represent a paradigm shift in the approach to safe and efficient intubation of all patients requiring general anesthesia. Although the results of this controlled trial are promising, larger studies in a broad population are needed to validate these findings. (Clinical trial registration number: NCT03879720.).

Use of an Ultra-slim Gastroscope to Accomplish Endoscopist-Facilitated Rescue Intubation During ERCP: A Novel Approach to Enhance Patient and Staff Safety.

BACKGROUND: ERCP is often performed under monitored anesthesia care (MAC) rather than general anesthesia (GA), with patients positioned semi-prone on the fluoroscopy table. Rarely, a MAC ERCP must be converted to GA due to hypoxia or retained food in the stomach. In these circumstances, standard intubation is associated with a significant delay and potential for patient/staff injury during repositioning. We report a novel endoscopist-driven approach to intubation during ERCP using an ultra-slim, flexible gastroscope with an endotracheal tube backloaded onto it. MATERIALS AND METHODS: We identified patients who underwent ERCP from 2014 to 2019, and MAC to GA conversion events. Mode of intubation (standard vs. endoscopist-facilitated) and patient/procedure characteristics were evaluated. All endoscopist-facilitated intubations were performed under anesthesiologist supervision. RESULTS: A total of 3409 patients underwent ERCP; 1568 (46%) GA and 1841 (54%) MAC. Of these, 42 (2.3%) required intubation during ERCP and 16 underwent endoscopist-facilitated intubation due to retained food in the stomach and/or hypoxia. In 3 patients, aspirated material was suctioned from the trachea and bronchi using the ultra-slim gastroscope. Immediate post-procedure extubation was successful in all endoscopist-facilitated intubation patients and none exhibited radiographic evidence of aspiration pneumonia. CONCLUSIONS: Endoscopist-facilitated intubation using an ultra-slim flexible gastroscope is feasible and expeditious for MAC to GA conversion during ERCP. This technique is readily accomplished in the semi-prone position, while standard intubation requires patient transfer from fluoroscopy table to gurney, with associated delay/risks. These data suggest that further study of this approach is warranted, and this may be the most favorable approach for intubation during ERCP.

Beyond duodenoscope-transmitted infections: Analysis of surface bioburden and UV-C mitigation within a tertiary care endoscopy unit.

BACKGROUND: An inpatient endoscopy unit is a care hub for patients from throughout the hospital and can be the site of health care-associated infections (HAIs). Shared surfaces and other nonmedical devices (keyboards) have been increasingly recognized as sites of pathogen transmission. Beyond standard cleaning of high-touch target areas, we queried whether the addition of automated devices delivering low-intensity doses of ultraviolet (UV)-C radiation could further reduce bioburden in an academic endoscopy unit. METHODS: Bioburden on previously identified high-touch/communal surfaces was measured before and after the installation of automated, low-intensity UV-light emitting devices (UV Angel) that passively monitor and disinfect targeted surfaces with Ultraviolet-C light (UV-C) light. RESULTS: High-touch sites (keyboards) had a baseline bacterial contamination of >80%, whereas individual procedure rooms and common areas had a >57% contamination rate. Following the implementation of automated UV-C light decontamination, bioburden was reduced on average by >91% at high-touch surfaces and within procedure rooms. DISCUSSION/CONCLUSIONS: Nonsterile hubs of patient care could serve as sites of "silent" HAI transmission. We have identified high-touch surfaces within an endoscopy unit that have a high bioburden of bacterial contamination and demonstrated that the installation of passive, automated UV-C light disinfection devices can reduce bioburden significantly, possibly mitigating HAI transmission between patients.

Anesthetic Considerations for Patients with Locked-In Syndrome Undergoing Endoscopic Procedures.

BACKGROUND Delivering safe anesthetic care to a patient unable to communicate easily and effectively with the anesthesia team presents many unique challenges. Communication may be limited by language, which can be resolved with translation services, or neurological conditions, such as stroke or traumatic brain injury, which are not easily remedied. In such patients, the inability to communicate effectively can lead to anxiety and negatively impact the patient-anesthesiologist relationship, especially when higher cognitive functions are preserved. CASE REPORT We present a case of a patient with locked-in syndrome (LIS), who presented to our endoscopy unit for a routine colonoscopy. The patient could only communicate with eye movements and blinking, thus limiting our ability to assess their pain or other needs in the perioperative period; however, she was otherwise cognitively intact. By utilizing the patient's home healthcare team and quickly adapting their unique communication methods during the perioperative period, we were able to provide an appropriate, safe anesthetic for this patient with LIS. CONCLUSIONS Many patients requiring an anesthetic are unable to effectively communicate due to language issues, hearing loss/mutism, neurological injury/stroke (aphasia), or developmental disabilities. The unique communication needs of this patient with LIS went beyond utilizing a translator and required the healthcare team to quickly learn a new communication method. We also discuss forms of intraoperative monitoring that can be used to differentiate consciousness from the anesthetized state in LIS patients, as well as making recommendations for future care of such patients.

Exploring the eukaryotic Yip and REEP/Yop superfamily of membrane-shaping adapter proteins (MSAPs): A cacophony or harmony of structure and function?

Polytopic cargo proteins are synthesized and exported along the secretory pathway from the endoplasmic reticulum (ER), through the Golgi apparatus, with eventual insertion into the plasma membrane (PM). While searching for proteins that could enhance cell surface expression of olfactory receptors, a new family of proteins termed "receptor expression-enhancing proteins" or REEPs were identified. These membrane-shaping hairpin proteins serve as adapters, interacting with intracellular transport machinery, to regulate cargo protein trafficking. However, REEPs belong to a larger family of proteins, the Yip (Ypt-interacting protein) family, conserved in yeast and higher eukaryotes. To date, eighteen mammalian Yip family members, divided into four subfamilies (Yipf, REEP, Yif, and PRAF), have been identified. Yeast research has revealed many intriguing aspects of yeast Yip function, functions that have not completely been explored with mammalian Yip family members. This review and analysis will clarify the different Yip family nomenclature that have encumbered prior comparisons between yeast, plants, and eukaryotic family members, to provide a more complete understanding of their interacting proteins, membrane topology, organelle localization, and role as regulators of cargo trafficking and localization. In addition, the biological role of membrane shaping and sensing hairpin and amphipathic helical domains of various Yip proteins and their potential cellular functions will be described. Lastly, this review will discuss the concept of Yip proteins as members of a larger superfamily of membrane-shaping adapter proteins (MSAPs), proteins that both shape membranes via membrane-sensing and hairpin insertion, and well as act as adapters for protein-protein interactions. MSAPs are defined by their localization to specific membranes, ability to alter membrane structure, interactions with other proteins via specific domains, and specific interactions/effects on cargo proteins.

Clevidipine-Induced Extreme Hypoxemia in a Neurosurgical Patient: A Case Report.

Clevidipine-induced pulmonary shunting is a little-reported adverse effect, manifesting as refractory hypoxemia, which may cause significant patient harm. We present the case of a mechanically ventilated patient admitted to the intensive care unit following a neurosurgical procedure. He was treated postoperatively with clevidipine for blood pressure management, and within 16 hours, he developed profound refractory hypoxemia, requiring increased ventilatory support. A workup for other causes was negative. The hypoxemia recovered within 1 hour of clevidipine discontinuation. Though other calcium channel blockers have been reported to cause pulmonary shunting from vasodilation, this is a novel case report for clevidipine-induced hypoxemia.

The Utility of Color Doppler to Confirm Endotracheal Tube Placement: A Pilot Study.

INTRODUCTION: Grayscale ultrasound (US) imaging has been used as an adjunct for confirming endotracheal tube (ETT) placement in recent years. The addition of color Doppler imaging (CDI) has been proposed to improve identification but has not been well studied. The aim of this study was to assess whether CDI improves correct localization of ETT placement. METHODS: A convenience sample of emergency and critical care physicians at various levels of training and experience participated in an online assessment. Participants viewed US video clips of patients, which included either tracheal or esophageal intubations captured in grayscale or with CDI; there were five videos of each for a total of 20 videos. Participants were asked to watch each clip and then assess the location of the ETT. RESULTS: Thirty-eight subjects participated in the online assessment. Levels of training included medical students (13%), emergency medicine (EM) residents (50%), EM attendings (32%), and critical care attendings (5%). The odds ratio of properly assessing tracheal placement using color relative to a grayscale imaging technique was 1.5 (p = 0.21). Regarding the correct assessment of esophageal placement, CDI had 1.4 times the odds of being correctly assessed relative to grayscale (p = 0.26). The relationship between training level and correct assessments was not significant for either tracheal or esophageal placements. CONCLUSION: In this pilot study we found no significant improvement in correct identification of ETT placement using color Doppler compared to grayscale ultrasound; however, there was a trend toward improvement that might be better elucidated in a larger study.

A Subarachnoid Hemorrhage Presenting as Massive Nasopharyngeal Bleeding: A Case Report.

Patients who present with a subarachnoid hemorrhage may have more than 1 intracranial aneurysm at risk, which may not be appreciated until a subsequent aneurysmal bleeding event occurs. We describe a patient who underwent successful aneurysmal clipping, but later presented urgently with large-volume epistaxis 48 hours after the procedure. After successful intubation of the patient, subsequent angiographic imaging determined that the massive intranasal/oral hemorrhage was due to bleeding through the former operative site, from rupture of a previously unrecognized aneurysm. This series of events demonstrates the importance of selecting the most at-risk aneurysm for surgical intervention.

Pharmacology and mechanism of action of pregabalin: the calcium channel alpha2-delta (alpha2-delta) subunit as a target for antiepileptic drug discovery.

Pregabalin (Lyrica) is a new antiepileptic drug that is active in animal seizure models. Pregabalin is approved in US and Europe for adjunctive therapy of partial seizures in adults, and also has been approved for the treatment of pain from diabetic neuropathy or post-herpetic neuralgia in adults. Recently, it has been approved for treatment of anxiety disorders in Europe. Pregabalin is structurally related to the antiepileptic drug gabapentin and the site of action of both drugs is similar, the alpha2-delta (alpha2-delta) protein, an auxiliary subunit of voltage-gated calcium channels. Pregabalin subtly reduces the synaptic release of several neurotransmitters, apparently by binding to alpha2-delta subunits, and possibly accounting for its actions in vivo to reduce neuronal excitability and seizures. Several studies indicate that the pharmacology of pregabalin requires binding to alpha2-delta subunits, including structure-activity analyses of compounds binding to alpha2-delta subunits and pharmacology in mice deficient in binding at the alpha2-delta Type 1 protein. The preclinical findings to date are consistent with a mechanism that may entail reduction of abnormal neuronal excitability through reduced neurotransmitter release. This review addresses the preclinical pharmacology of pregabalin, and also the biology of the high affinity binding site, and presumed site of action.

Differential targeting and function of alpha2A and alpha2C adrenergic receptor subtypes in cultured sympathetic neurons.

Previous research suggested that alpha2A and alpha2C adrenergic receptor (AR) subtypes have overlapping but unique physiological roles in neuronal signaling; however, the basis for these dissimilarities is not completely known. To better understand the observed functional differences between these autoreceptors, we investigated targeting and signaling of endogenously expressed alpha2A and alpha2CARs in cultured sympathetic ganglion neurons (SGN). At Days 1 and 4, alpha2A and alpha2CARs could be readily detected in SGN from wild-type mice. By Day 8, alpha2A ARs were targeted to cell body, as well as axonal and dendritic sites, whereas alpha2C ARs were primarily localized to an intracellular vesicular pool within the cell body and proximal dendritic projections. Expression of synaptic vesicle marker protein SV2 did not differ at Day 8 nor co-localize with either subtype. By Day 16, however, alpha2C ARs had relocated to somatodendritic and axonal sites and, unlike alpha2A ARs, co-localized with SV2 at synaptic contact sites. Consistent with a functional role for alpha2 ARs, we also observed that dexmedetomidine stimulation of cultured SGN more efficiently inhibited depolarization-induced calcium entry into older, compared to younger, cultures. These results provide direct evidence of distinct developmental patterns of endogenous alpha2A and alpha2C AR targeting and function in a native cell system and that maturation of SGN in culture leads to alterations in neuronal properties required for proper targeting. More importantly, the co-localization at Day 16 of alpha2C ARs at sites of synaptic contact may partially explain the differential modulation of neurotransmitter release and responsiveness to action potential frequency observed between alpha2A and alpha2C ARs in SGN.

Anesthesia for older patients with hypertrophic cardiomyopathy: Is there cause for concern?

Hypertrophic cardiomyopathy (HCM) may remain clinically silent and undiagnosed until patients reach advanced age. We describe 2 older patients with previously undetected and probable late-onset HCM whose preoperative cardiac examination revealed only the presence of a systolic murmur. Both patients were diagnosed with HCM by perioperative echocardiography. We provide an algorithm for the evaluation of murmurs detected during the preoperative anesthesia evaluation, with emphasis on the clinical characteristics of HCM, and we discuss the perioperative management of these patients. In addition, recent findings concerning the natural progression of HCM are discussed, revealing differences between HCM in younger patient populations and that in older patient populations and its implications for anesthetic management.

Diagnosis of an unsuspected maternal hemorrhage via fetal heart rate tracing.

Early detection of placental abruption often relies on the observation of vaginal bleeding; however, overt bleeding does not always occur. We report the case of an unsuspected placental abruption diagnosis that was prompted by an internal fetal scalp electrode tracing. The presence of a "normal" fetal heart rate (FHR) of approximately 150 beats per minute with poor variability, which matched the maternal heart rate (MHR), suggested that the tracing was not of fetal origin. An urgent ultrasound examination revealed a fetal demise with a possible concealed abruption, proving that the scalp electrode tracing was actually maternal in origin. Though reports of transmission of MHR via a deceased fetus are not new, it is uncommon for MHR to mimic a normal, reassuring FHR. This report reinforces the need for anesthesiologists to be adept at interpreting and integrating FHR monitors with maternal monitors prior to initiation of epidural analgesia.

Common α2A and α2C adrenergic receptor polymorphisms do not affect plasma membrane trafficking.

Various naturally occurring polymorphic forms of human G protein-coupled receptors (GPCRs) have been identified and linked to diverse pathological diseases, including receptors for vasopressin type 2 (nephrogenic diabetes insipidus) and gonadotropin releasing hormone (hypogonadotropic hypogonadism). In most cases, polymorphic amino acid mutations disrupt protein folding, altering receptor function as well as plasma membrane expression. Other pathological GPCR variants have been found that do not alter receptor function, but instead affect only plasma membrane trafficking (e.g., delta opiate and histamine type 1 receptors). Thus, altered membrane trafficking with retained receptor function may be another mechanism causing polymorphic GPCR dysfunction. Two common human α2A and α2C adrenergic receptor (AR) variants have been identified (α2A N251K and α2C Δ322-325 ARs), but pharmacological analysis of ligand binding and second messenger signaling has not consistently demonstrated altered receptor function. However, possible alterations in plasma membrane trafficking have not been investigated. We utilized a systematic approach previously developed for the study of GPCR trafficking motifs and accessory proteins to assess whether these α2 AR variants affected intracellular trafficking or plasma membrane expression. By combining immunofluorescent microscopy, glycosidic processing analysis, and quantitative fluorescent-activated cell sorting (FACS), we demonstrate that neither variant receptor had altered intracellular localization, glycosylation, nor plasma membrane expression compared to wild-type α2 ARs. Therefore, pathopharmacological properties of α2A N251K and α2C Δ322-325 ARs do not appear to be due to altered receptor pharmacology or plasma membrane trafficking, but may involve interactions with other intracellular signaling cascades or proteins.

REEP1 and REEP2 proteins are preferentially expressed in neuronal and neuronal-like exocytotic tissues.

The six members of the Receptor Expression Enhancing Protein (REEP) family were originally identified based on their ability to enhance heterologous expression of olfactory receptors and other difficult to express G protein-coupled receptors. Interestingly, REEP1 mutations have been linked to neurodegenerative disorders of upper and lower motor neurons, hereditary spastic paraplegia (HSP) and distal hereditary motor neuropathy type V (dHMN-V). The closely related REEP2 isoform has not demonstrated any such disease linkage. Previous research has suggested that REEP1 mRNA is ubiquitously expressed in brain, muscle, endocrine, and multiple other organs, inconsistent with the neurodegenerative phenotype observed in HSP and dHMN-V. To more fully examine REEP1 expression, we developed and characterized a new REEP1 monoclonal antibody for both immunoblotting and immunofluorescent microscopic analysis. Unlike previous RT-PCR studies, immunoblotting demonstrated that REEP1 protein was not ubiquitous; its expression was restricted to neuronal tissues (brain, spinal cord) and testes. Gene expression microarray analysis demonstrated REEP1 and REEP2 mRNA expression in superior cervical and stellate sympathetic ganglia tissue. Furthermore, expression of endogenous REEP1 was confirmed in cultured murine sympathetic ganglion neurons by RT-PCR and immunofluorescent staining, with expression occurring between Day 4 and Day 8 of culture. Lastly, we demonstrated that REEP2 protein expression was also restricted to neuronal tissues (brain and spinal cord) and tissues that exhibit neuronal-like exocytosis (testes, pituitary, and adrenal gland). In addition to sensory tissues, expression of the REEP1/REEP2 subfamily appears to be restricted to neuronal and neuronal-like exocytotic tissues, consistent with neuronally restricted symptoms of REEP1 genetic disorders.

Systematic and quantitative analysis of G protein-coupled receptor trafficking motifs.

Plasma membrane expression of G protein-coupled receptors (GPCRs) is a dynamic process balancing anterograde and retrograde trafficking. Multiple interrelated cellular processes determine the final level of cell surface expression, including endoplasmic reticulum (ER) export/retention, receptor internalization, recycling, and degradation. These processes are highly regulated to achieve specific localization to subcellular domains (e.g., dendrites or basolateral membranes) and to affect receptor signaling. Analysis of potential ER trafficking motifs within GPCRs requires careful consideration of intracellular dynamics, such as protein folding, ER export and retention, and glycosylation. This chapter presents an approach and methods for qualitative and quantitative assessment of these processes to aid in accurate identification of GPCR trafficking motifs, utilizing the analysis of a hydrophobic extracellular trafficking motif in α2C adrenergic receptors as a model system.

REEPs are membrane shaping adapter proteins that modulate specific g protein-coupled receptor trafficking by affecting ER cargo capacity.

Receptor expression enhancing proteins (REEPs) were identified by their ability to enhance cell surface expression of a subset of G protein-coupled receptors (GPCRs), specifically GPCRs that have proven difficult to express in heterologous cell systems. Further analysis revealed that they belong to the Yip (Ypt-interacting protein) family and that some REEP subtypes affect ER structure. Yip family comparisons have established other potential roles for REEPs, including regulation of ER-Golgi transport and processing/neuronal localization of cargo proteins. However, these other potential REEP functions and the mechanism by which they selectively enhance GPCR cell surface expression have not been clarified. By utilizing several REEP family members (REEP1, REEP2, and REEP6) and model GPCRs (α2A and α2C adrenergic receptors), we examined REEP regulation of GPCR plasma membrane expression, intracellular processing, and trafficking. Using a combination of immunolocalization and biochemical methods, we demonstrated that this REEP subset is localized primarily to ER, but not plasma membranes. Single cell analysis demonstrated that these REEPs do not specifically enhance surface expression of all GPCRs, but affect ER cargo capacity of specific GPCRs and thus their surface expression. REEP co-expression with α2 adrenergic receptors (ARs) revealed that this REEP subset interacts with and alter glycosidic processing of α2C, but not α2A ARs, demonstrating selective interaction with cargo proteins. Specifically, these REEPs enhanced expression of and interacted with minimally/non-glycosylated forms of α2C ARs. Most importantly, expression of a mutant REEP1 allele (hereditary spastic paraplegia SPG31) lacking the carboxyl terminus led to loss of this interaction. Thus specific REEP isoforms have additional intracellular functions besides altering ER structure, such as enhancing ER cargo capacity, regulating ER-Golgi processing, and interacting with select cargo proteins. Therefore, some REEPs can be further described as ER membrane shaping adapter proteins.