Cost-Effectiveness of Monitoring Patients Post-Stroke With Mobile ECG During the Hospital Stay.

Background The effectiveness of a nurse-led in-hospital monitoring protocol with mobile ECG (iECG) was investigated for detecting atrial fibrillation in patients post-ischemic stroke or post-transient ischemic attack. The study aimed to assess the cost-effectiveness of using iECG during the initial hospital stay compared with standard 24-hour Holter monitoring. Methods and Results A Markov microsimulation model was constructed to simulate the lifetime health outcomes and costs. The rate of atrial fibrillation detection in iECG and Holter monitoring during the in-hospital phase and characteristics of modeled population (ie, age, sex, CHA2DS2-VASc) were informed by patient-level data. Costs related to recurrent stroke, stroke management, medications (new oral anticoagulants), and rehabilitation were included. The cost-effectiveness analysis outcome was calculated as an incremental cost per quality-adjusted life-year gained. As results, monitoring patients with iECG post-stroke during the index hospitalization was associated with marginally higher costs (A$31 196) and greater benefits (6.70 quality-adjusted life-years) compared with 24-hour Holter surveillance (A$31 095 and 6.66 quality-adjusted life-years) over a 20-year time horizon, with an incremental cost-effectiveness ratio of $3013/ quality-adjusted life-years. Monitoring patients with iECG also contributed to lower recurrence of stroke and stroke-related deaths (140 recurrent strokes and 20 deaths avoided per 10 000 patients). The probabilistic sensitivity analyses suggested iECG is highly likely to be a cost-effective intervention (100% probability). Conclusions A nurse-led iECG monitoring protocol during the acute hospital stay was found to improve the rate of atrial fibrillation detection and contributed to slightly increased costs and improved health outcomes. Using iECG to monitor patients post-stroke during initial hospitalization is recommended to complement routine care.

Impact of COVID-19 pandemic and lockdown on eye emergencies.

BACKGROUND: To characterise and compare ocular pathologies presenting to an emergency eye department (EED) during the COVID-19 pandemic in 2020 against an equivalent period in 2019. METHODS: Electronic patient records of 852 patients in 2020 and 1818 patients in 2019, attending the EED at a tertiary eye centre (University Hospitals of Leicester, UK) were analysed. Data was extracted over a 31-day period during: (study period 1 (SP1)) COVID-19 pandemic lockdown in UK (24th March 2020-23rd April 2020) and (study period 2 (SP2)) the equivalent 2019 period (24th March 2019-23rd April 2019). RESULTS: A 53% reduction in EED attendance was noted during lockdown. The top three pathologies accounting for >30% of the caseload were trauma-related, keratitis and uveitis in SP1 in comparison to conjunctivitis, trauma-related and blepharitis in SP2. The overall number of retinal tears and retinal detachments (RD) were lower in SP1, the proportion of macula-off RD's (84.6%) was significantly (p = 0.0099) higher in SP1 (vs 42.9% in SP2). CONCLUSION: COVID-19 pandemic related lockdown has had a significant impact on the range of presenting conditions to the EED. Measures to stop spread of COVID-19 such as awareness of hand hygiene practices, social distancing measures and school closures could have an indirect role in reducing spread of infective conjunctivitis. The higher proportion of macula-off RD and lower number of retinal tears raises possibility of delayed presentation in these cases. Going forward, we anticipate additional pressures on EED and other subspecialty services due to complications and associated morbidity from delayed presentations.

Nurse Led Smartphone Electrographic Monitoring for Atrial Fibrillation after Ischemic Stroke: SPOT-AF.

BACKGROUND AND PURPOSE: Paroxysmal atrial fibrillation (PAF) underlying acute stroke frequently evades detection by standard practice, considered to be a combination of routine electrocardiogram (ECG) monitoring, and 24-hour Holter recordings. We hypothesized that nurse-led in-hospital intermittent monitoring approach would increase PAF detection rate. METHODS: We recruited patients hospitalised for stroke/transient ischemic attack, without history of atrial fibrillation (AF), in a prospective multi-centre observational study. Patients were monitored using a smartphone-enabled handheld ECG (iECG) during routine nursing observations, and underwent 24-hour Holter monitoring according to local practice. The primary outcome was comparison of AF detection by nurse-led iECG versus Holter monitoring in patients who received both tests: secondary outcome was oral anticoagulant commencement at 3-month following PAF detection. RESULTS: One thousand and seventy-nine patients underwent iECG monitoring: 294 had iECG and Holter monitoring. AF was detected in 25/294 (8.5%) by iECG, and 8/294 (2.8%) by 24-hour Holter recordings (P<0.001). Median duration from stroke onset to AF detection for iECG was 3 days (interquartile range [IQR], 2 to 6) compared with 7 days (IQR, 6 to 10) for Holter recordings (P=0.02). Of 25 patients with AF detected by iECG, 11 were commenced on oral anticoagulant, compared to 5/8 for Holter. AF was detected in 8.8% (69/785 patients) who underwent iECG recordings only (P=0.8 vs. those who had both iECG and 24-hour Holter). CONCLUSIONS: Nurse-led in-hospital iECG surveillance after stroke is feasible and effective and detects more PAF earlier and more frequently than routine 24-hour Holter recordings. Screening with iECG could be incorporated into routine post-stroke nursing observations to increase diagnosis of PAF, and facilitate institution of guideline-recommended anticoagulation.

Analysis of outcomes achieved with squamous cell carcinomas of the anus in a single university hospital over the last two decades: Clinical response rate, relapse and survival of 190 patients.

BACKGROUND AND OBJECTIVES: We reviewed our series of anal squamous cell carcinomas (ASCC) treated over the last two decades. METHODS: ASCC patients undergoing treatment at the Leicester Royal Infirmary between 1998 and 2016 were selected. Age, gender, pathological tumor characteristics, treatment adopted, the overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS) at 5-year follow-up were recorded and calculated. RESULTS: A total of 190 ASCC were reviewed, of these 64.2% (n = 122) received primary radical chemoradiotherapy. Complete response rate was 92.6% (n = 113) and four patients with residual disease underwent a salvage APER. Twenty-eight patients experienced recurrent disease (23.0%) either systemic (n = 8), local (n = 14), or both (n = 6); six had a salvage APER. Complete follow-up data are available for 63.1% patients (77/122). Overall, the locoregional failure rate of primary chemoradiotherapy (residual + recurrent disease) was present in 29 patients (29/122; 23.8%). OS was 41.6% CSS was 69.2% and DFS 60.0% at 5 years follow-up. CONCLUSIONS: In our series of ASCC primary chemoradiotherapy had achieved significant initial complete response rates, however, long term-follow ups still present systemic and local recurrences. APR is able to treat 30% of the pelvic recurrences (6/20), the others are either associated with systemic disease or locally inoperable masses.

Androgens trigger different growth responses in genetically identical human hair follicles in organ culture that reflect their epigenetic diversity in life.

Male sex hormones-androgens-regulate male physique development. Without androgen signaling, genetic males appear female. During puberty, increasing androgens harness the hair follicle's unique regenerative ability to replace many tiny vellus hairs with larger, darker terminal hairs ( e.g., beard). Follicle response is epigenetically varied: some remain unaffected ( e.g., eyelashes) or are inhibited, causing balding. How sex steroid hormones alter such developmental processes is unclear, despite high incidences of hormone-driven cancer, hirsutism, and alopecia. Unfortunately, existing development models are not androgen sensitive. Here, we use hair follicles to establish an androgen-responsive human organ culture model. We show that women's intermediate facial follicles respond to men's higher androgen levels by synthesizing more hair over several days, unlike donor-matched, androgen-insensitive, terminal follicles. We demonstrate that androgen receptors-androgen-activated gene transcription regulators-are required and are present in vivo within these follicles. This is the first human organ that involves multiple cell types that responds appropriately to hormones in prolonged culture, in a way which mirrors its natural behavior. Thus, intermediate hair follicles offer a hormone-switchable human model with exceptional, unique availability of genetically identical, but epigenetically hormone-insensitive, terminal follicles. This should enable advances in understanding sex steroid hormone signaling, gene regulation, and developmental and regenerative systems and facilitate better therapies for hormone-dependent disorders.-Miranda, B. H., Charlesworth, M. R., Tobin, D. J., Sharpe, D. T., Randall, V. A. Androgens trigger different growth responses in genetically identical human hair follicles in organ culture that reflect their epigenetic diversity in life.

Juvenile myelomonocytic leukemia-associated variants are associated with neo-natal lethal Noonan syndrome.

Gain-of-function variants in some RAS-MAPK pathway genes, including PTPN11 and NRAS, are associated with RASopathies and/or acquired hematological malignancies, most notably juvenile myelomonocytic leukemia (JMML). With rare exceptions, the spectrum of germline variants causing RASopathies does not overlap with the somatic variants identified in isolated JMML. Studies comparing these variants suggest a stronger gain-of-function activity in the JMML variants. As JMML variants have not been identified as germline defects and have a greater impact on protein function, it has been speculated that they would be embryonic lethal. Here we identified three variants, which have previously only been identified in isolated somatic JMML and other sporadic cancers, in four cases with a severe pre- or neo-natal lethal presentation of Noonan syndrome. These cases support the hypothesis that these stronger gain-of-function variants are rarely compatible with life.

Rectal cancers with microscopic circumferential resection margin involvement (R1 resections): Survivals, patterns of recurrence, and prognostic factors.

BACKGROUND AND OBJECTIVES: We have reviewed our series of rectal cancer patients with circumferential resection margin involvement (R1) with particular regard to survival and prognostic factors. METHODS: R1 rectal cancer patients undergoing surgery at the Leicester Royal Infirmary between 1998 and 2008. Age, gender, radiological, and pathological tumor characteristics, neoadjuvant and adjuvant therapies were examined as prognostic factors on the overall survival (OS) and disease-free survival (DFS) at 5-year follow-up. RESULTS: A total of 885 rectal cancers were reviewed. Six hundred ninety-nine patients underwent a mesorectal excision and 71 of them were R1 resections (12.9%). OS was 43.7% (CI95% 33.5-53.8%; median survival 39 months). DFS was 57.4% (CI95% 43.0-71.8%; median survival 31 months). Pelvic recurrence rate occurred in 16 patients (26.2%, CI95% 16.5-36.0%), systemic recurrence rate in 23 patients (37.7%, CI95% 25.5-49.9%). At Cox-regression LNR and adjuvant chemotherapy were associated with both OS and DFS. No significant association was found between OS or DFS and adjuvant radiotherapy. CONCLUSIONS: In our series of R1 patients, the rates of local recurrence and OS at 5 years were 26.2% and 43.7%, respectively. Factors influencing systemic recurrences (LNR, adjuvant chemotherapy) are more associated with OS and DFS than those potentially affecting locoregional recurrences (adjuvant radiotherapy). J. Surg. Oncol. 2016;114:642-648. © 2016 Wiley Periodicals, Inc.

Circumferential resection margins and perineal complications after neoadjuvant long-course chemoradiotherapy followed by extralevator abdominoperineal excision of the rectum: Five years of activity at a single institution.

BACKGROUND: Prone extralevator abdominoperineal excision of the rectum (ELAPE) has been introduced to improve the circumferential resection margins (CRM) compared with traditional APER. OBJECTIVE: We present short-term results achieved with prone ELAPE preceded by neoadjuvant chemoradiotherapy during the last 5 years of activity. DESIGN: A retrospective review was conducted. SETTINGS AND PATIENTS: Prone ELAPE operations performed between September 2010 and August 2014 at Leicester Royal Infirmary preceded by neoadjuvant chemoradiotherapy. INTERVENTIONS AND MAIN OUTCOME MEASURES: Data regarding demographics, staging, neoadjuvant therapies, intraoperative perforations, and perineal complications were collected. RESULTS: Seventy-two patients were included. Pretreatment radiological T4 were 25.0%, histological T4 2.8%. Intraoperative perforations occurred in 2.8%, CRM was involved in 11.1%. Perineal complications consisted of superficial wound infections (20.8%), full thickness dehiscences (16.7%), hematomas (9.7%), pelvic collections (6.9%), and perineal hernias (5.6%). CONCLUSIONS: In our experience, prone ELAPE preceded by long-course chemoradiotherapy has been successfully used in the last 5 years to resect low rectal tumors. Perineal wound complications rates are similar to those presented in series using direct perineal closures. J. Surg. Oncol. 2016;114:86-90. © 2016 Wiley Periodicals, Inc.

The Chemical Validation and Standardization Platform (CVSP): large-scale automated validation of chemical structure datasets.

BACKGROUND: There are presently hundreds of online databases hosting millions of chemical compounds and associated data. As a result of the number of cheminformatics software tools that can be used to produce the data, subtle differences between the various cheminformatics platforms, as well as the naivety of the software users, there are a myriad of issues that can exist with chemical structure representations online. In order to help facilitate validation and standardization of chemical structure datasets from various sources we have delivered a freely available internet-based platform to the community for the processing of chemical compound datasets. RESULTS: The chemical validation and standardization platform (CVSP) both validates and standardizes chemical structure representations according to sets of systematic rules. The chemical validation algorithms detect issues with submitted molecular representations using pre-defined or user-defined dictionary-based molecular patterns that are chemically suspicious or potentially requiring manual review. Each identified issue is assigned one of three levels of severity - Information, Warning, and Error - in order to conveniently inform the user of the need to browse and review subsets of their data. The validation process includes validation of atoms and bonds (e.g., making aware of query atoms and bonds), valences, and stereo. The standard form of submission of collections of data, the SDF file, allows the user to map the data fields to predefined CVSP fields for the purpose of cross-validating associated SMILES and InChIs with the connection tables contained within the SDF file. This platform has been applied to the analysis of a large number of data sets prepared for deposition to our ChemSpider database and in preparation of data for the Open PHACTS project. In this work we review the results of the automated validation of the DrugBank dataset, a popular drug and drug target database utilized by the community, and ChEMBL 17 data set. CVSP web site is located at http://cvsp.chemspider.com/. CONCLUSION: A platform for the validation and standardization of chemical structure representations of various formats has been developed and made available to the community to assist and encourage the processing of chemical structure files to produce more homogeneous compound representations for exchange and interchange between online databases. While the CVSP platform is designed with flexibility inherent to the rules that can be used for processing the data we have produced a recommended rule set based on our own experiences with the large data sets such as DrugBank, ChEMBL, and data sets from ChemSpider.

Sensitivity and specificity of the empirical lymphocyte genome sensitivity (LGS) assay: implications for improving cancer diagnostics.

Lymphocyte responses from 208 individuals: 20 with melanoma, 34 with colon cancer, and 4 with lung cancer (58), 18 with suspected melanoma, 28 with polyposis, and 10 with COPD (56), and 94 healthy volunteers were examined. The natural logarithm of the Olive tail moment (OTM) was plotted for exposure to UVA through 5 different agar depths (100 cell measurements/depth) and analyzed using a repeated measures regression model. Responses of patients with cancer plateaued after treatment with different UVA intensities, but returned toward control values for healthy volunteers. For precancerous conditions and suspected cancers, intermediate responses occurred. ROC analysis of mean log OTMs, for cancers plus precancerous/suspect conditions vs. controls, cancer vs. precancerous/suspect conditions plus controls, and cancer vs. controls, gave areas under the curve of 0.87, 0.89, and 0.93, respectively (P<0.001). Optimization allowed test sensitivity or specificity to approach 100% with acceptable complementary measures. This modified comet assay could represent a stand-alone test or an adjunct to other investigative procedures for detecting cancer.

Prognostic value of baseline FDG uptake on PET-CT in esophageal carcinoma.

AIM: To evaluate the influence of baseline maximum standardized uptake value (SUVmax) on survival in a cohort of patients, undergoing positron emission tomography-computed tomography (PET-CT) scan for esophageal carcinoma. METHODS: The pre-treatment SUVmax numeric reading was determined in patients with confirmed esophageal or junctional cancer having PET-CT scan during the time period 1(st) January 2007 until 31(st) July 2012. A minimum follow up of 12 mo was required. Patients were subdivided into quartiles according to SUVmax value and the influence of SUVmax on survival was assessed using univariate and multivariate analysis. The following pre-treatment factors were investigated: patient characteristics, tumor characteristics and planned treatment. RESULTS: The study population was 271 patients (191 male) with esophageal or junctional carcinoma. The median age was 65 years (range 40-85) and histologic subtype was adenocarcinoma in 197 patients and squamous carcinoma in 74 patients. The treatment intent was radical in 182 and palliative in 89 patients. SUVmax was linked to histologic subtype (P = 0.008), tumor site (P = 0.01) and Union for International Cancer Control (UICC) stage (P < 0.001). On univariate analysis, prognosis was significantly associated with SUVmax (P = 0.001), T-stage (P < 0.001) and UICC stage (P < 0.001). On multivariate analysis, only T-stage and UICC stage remained significant. CONCLUSION: Pretreatment SUVmax was not a useful marker in isolation for determining prognosis of patients with esophageal carcinoma.

Synthesis and properties of chemiluminescent acridinium ester labels with fluorous tags.

Acridinium dimethylphenyl esters are highly sensitive chemiluminescent labels that are used in clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of the cationic surfactant cetyltrimethylammonium chloride (CTAC). CTAC compresses emission times of these labels to <5 seconds and also increases overall light yield 3-4 fold. The observed enhancement in acridinium ester chemiluminescence (light yield) is quite sensitive to the polarity of the micellar interface. In the current study, we report the synthesis of new acridinium ester labels with fluorous tags of varying fluorine content and their chemiluminescence in the presence of cationic micelles of CTAC, anionic micelles of sodium perfluorooctanoate (SPFO) as well as mixed micelles of CTAC and SPFO. These studies indicate that in the presence of the mixed micelle system of CTAC and SPFO and at low mole fractions of SPFO, polarity of the mixed micelle interface is lower than that of CTAC leading to a greater enhancement of chemiluminescence for both fluorinated acridinium esters as well as a structurally analogous but non-fluorinated acridinium ester. Chemiluminescence stability of the fluorinated acridinium esters was either comparable to or better than the stability of the non-fluorinated acridinium ester. Non-specific binding to paramagnetic microparticles was higher for fluorinated acridinium esters requiring a surfactant wash to reduce their non-specific binding to the same extent as that observed for the non-fluorinated acridinium ester.

Bone morphogenetic protein signaling suppresses wound-induced skin repair by inhibiting keratinocyte proliferation and migration.

Bone morphogenetic protein (BMP) signaling plays a key role in the control of skin development and postnatal remodeling by regulating keratinocyte proliferation, differentiation, and apoptosis. To study the role of BMPs in wound-induced epidermal repair, we used transgenic mice overexpressing the BMP downstream component Smad1 under the control of a K14 promoter as an in vivo model, as well as ex vivo and in vitro assays. K14-caSmad1 (transgenic mice overexpressing a constitutively active form of Smad1 under K14 promoter) mice exhibited retarded wound healing associated with significant inhibition of proliferation and increased apoptosis in healing wound epithelium. Furthermore, microarray and quantitative real-time reverse-transcriptase-PCR (qRT-PCR) analyses revealed decreased expression of a number of cytoskeletal/cell motility-associated genes including wound-associated keratins (Krt16, Krt17) and Myosin VA (Myo5a), in the epidermis of K14-caSmad1 mice versus wild-type (WT) controls during wound healing. BMP treatment significantly inhibited keratinocyte migration ex vivo, and primary keratinocytes of K14-caSmad1 mice showed retarded migration compared with WT controls. Finally, small interfering RNA (siRNA)-mediated silencing of BMPR-1B in primary mouse keratinocytes accelerated cell migration and was associated with increased expression of Krt16, Krt17, and Myo5a compared with controls. Thus, this study demonstrates that BMPs inhibit keratinocyte proliferation, cytoskeletal organization, and migration in regenerating skin epithelium during wound healing, and raises a possibility for using BMP antagonists for the management of chronic wounds.

Targeted next generation sequencing in SPAST-negative hereditary spastic paraplegia.

Molecular characterization is important for an accurate diagnosis in hereditary spastic paraplegia (HSP). Mutations in the gene SPAST (SPG4) are the most common cause of autosomal dominant forms. We performed targeted next generation sequencing (NGS) in a SPAST-negative HSP sample. Forty-four consecutive HSP patients were recruited from an adult neurogenetics clinic in Sydney, Australia. SPAST mutations were confirmed in 17 subjects, and therefore 27 SPAST-negative patients were entered into this study. Patients were screened according to mode of inheritance using a PCR-based library and NGS (Roche Junior 454 sequencing platform). The screening panel included ten autosomal dominant (AD) and nine autosomal recessive (AR) HSP-causing genes. A genetic cause for HSP was identified in 25.9 % (7/27) of patients, including 1/12 classified as AD and 6/15 as AR or sporadic inheritance. Several forms of HSP were identified, including one patient with SPG31, four with SPG7 (with one novel SPG7 mutation) and two with SPG5 (including two novel CYP7B1 frameshift mutations). Additional clinical features were noted, including optic atrophy and ataxia for patients with SPG5 and ataxia and a chronic progressive external ophthalmoplegia-like phenotype for SPG7. This protocol enabled the identification of a genetic cause in approximately 25 % of patients in whom one of the most common genetic forms of HSP (SPG4) was excluded. Targeted NGS may be a useful method to screen for mutations in multiple genes associated with HSP. More studies are warranted to determine the optimal approach to achieve a genetic diagnosis in this condition.

Synthesis and properties of differently charged chemiluminescent acridinium ester labels.

Chemiluminescent acridinium dimethylphenyl esters containing N-sulfopropyl groups in the acridinium ring are highly sensitive, hydrophilic labels that are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of a cationic surfactant. At physiological pH, N-sulfopropyl acridinium esters exist as water adducts that are commonly referred to as pseudobases. Pseudobase formation, which results from addition of water to the zwitterionic N-sulfopropyl acridinium ring, neutralizes the positive charge on the acridinium nitrogen and imparts a net negative charge to the label due to the sulfonate moiety. As a consequence, N-sulfopropyl acridinium ester conjugates of small molecule haptens as well as large molecules such as proteins gain negative charges at neutral pH. In the current study, we describe the synthesis and properties of two new hydrophilic acridinium dimethylphenyl ester labels where the net charge in the labels was altered. In one label, the structure of the hydrophilic N-alkyl group attached to the acridinium ring was changed so that the pseudobase of the label contains no net charge. In the second acridinium ester, two additional negative charges in the form of sulfopropyl groups were added to the acridinium ring to make this label's pseudobase strongly anionic. Chemiluminescence measurements of these labels, as well as their conjugates of an antibody with a neutral pI, indicate that acridinium ester charge while having a modest effect on emission kinetics has little influence on light output. However, our results demonstrate that acridinium ester charge can affect protein pI, apparent chemiluminescence stability and non-specific binding of protein conjugates to microparticles. These results emphasize the need for careful consideration of acridinium ester charge in order to optimize reagent stability and performance in immunoassays. In the current study, we observed that for a neutral protein, an acridinium ester with a hydrophilic but charge-neutral N-alkyl group afforded faster light emission, lower non-specific binding and better chemiluminescence stability than an analogous label with an anionic N-alkyl group.

Fine-scale genetic response to landscape change in a gliding mammal.

Understanding how populations respond to habitat loss is central to conserving biodiversity. Population genetic approaches enable the identification of the symptoms of population disruption in advance of population collapse. However, the spatio-temporal scales at which population disruption occurs are still too poorly known to effectively conserve biodiversity in the face of human-induced landscape change. We employed microsatellite analysis to examine genetic structure and diversity over small spatial (mostly 1-50 km) and temporal scales (20-50 years) in the squirrel glider (Petaurus norfolcensis), a gliding mammal that is commonly subjected to a loss of habitat connectivity. We identified genetically differentiated local populations over distances as little as 3 km and within 30 years of landscape change. Genetically isolated local populations experienced the loss of genetic diversity, and significantly increased mean relatedness, which suggests increased inbreeding. Where tree cover remained, genetic differentiation was less evident. This pattern was repeated in two landscapes located 750 km apart. These results lend support to other recent studies that suggest the loss of habitat connectivity can produce fine-scale population genetic change in a range of taxa. This gives rise to the prediction that many other vertebrates will experience similar genetic changes. Our results suggest the future collapse of local populations of this gliding mammal is likely unless habitat connectivity is maintained or restored. Landscape management must occur on a fine-scale to avert the erosion of biodiversity.

Chemiluminescence from alkoxy-substituted acridinium dimethylphenyl ester labels.

Chemiluminescent acridinium dimethylphenyl ester labels are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered by alkaline peroxide in the presence of the cationic surfactant cetyltrimethylammonium chloride (CTAC). The surfactant plays a critical role in the chemiluminescence process of these labels by both accelerating their emission kinetics and increasing total light output enabling high throughout and improved assay sensitivity in automated immunoassays. Despite the surfactant's crucial role in the chemiluminescent reaction, no study has investigated how structural perturbations in the acridinium ring could impact the influence of the surfactant. We describe herein the synthesis and properties of three new alkoxy-substituted, acridinium dimethylphenyl esters where the nature of the alkoxy group in the acridinium ring was varied (hydrophobic or hydrophilic). Chemiluminescence measurements of these alkoxy-substituted labels indicate that hydrophilic functional groups in the acridinium ring, in particular sulfobetaine zwitterions, disrupt surfactant-mediated compression of emission times but not enhancement of light yield. These results support the hypothesis that surfactant-mediated effects require the binding of two different reaction intermediates to surfactant aggregates and, that surfactants influence light emission from acridinium esters by two separate mechanisms. Our studies also indicate that preservation of both surfactant effects on acridinium ester chemiluminescence and low non-specific binding of the label can be achieved with a relatively hydrophobic acridinium ring coupled to a hydrophilic phenolic ester leaving group.