Deconvolution of the tumor-educated platelet transcriptome reveals activated platelet and inflammatory cell transcript signatures.

Tumor-educated platelets (TEPs) are a potential method of liquid biopsy for the diagnosis and monitoring of cancer. However, the mechanism underlying tumor education of platelets is not known, and transcripts associated with TEPs are often not tumor-associated transcripts. We demonstrated that direct tumor transfer of transcripts to circulating platelets is an unlikely source of the TEP signal. We used CDSeq, a latent Dirichlet allocation algorithm, to deconvolute the TEP signal in blood samples from patients with glioblastoma. We demonstrated that a substantial proportion of transcripts in the platelet transcriptome are derived from non-platelet cells, and the use of this algorithm allows the removal of contaminant transcripts. Furthermore, we used the results of this algorithm to demonstrate that TEPs represent a subset of more activated platelets, which also contain transcripts normally associated with non-platelet inflammatory cells, suggesting that these inflammatory cells, possibly in the tumor microenvironment, transfer transcripts to platelets that are then found in circulation. Our analysis suggests a useful and efficient method of processing TEP transcriptomic data to enable the isolation of a unique TEP signal associated with specific tumors.

REM sleep in narcolepsy.

Narcolepsy is mainly associated with excessive daytime sleepiness, but the characteristic feature is abnormal rapid eye movement (REM) sleep phenomena. REM sleep disturbances can manifest as cataplexy (in narcolepsy type 1), sleep paralysis, sleep-related hallucinations, REM sleep behavior disorder, abnormal dreams, polysomnographic evidence of REM sleep disruption with sleep-onset REM periods, and fragmented REM sleep. Characterization of REM sleep and related symptoms facilitates the differentiation of narcolepsy from other central hypersomnolence disorders and aids in distinguishing between narcolepsy types 1 and 2. A circuit comprising regions within the brainstem, forebrain, and hypothalamus is involved in generating and regulating REM sleep, which is influenced by changes in monoamines, acetylcholine, and neuropeptides. REM sleep is associated with brainstem functions, including autonomic control, and REM sleep disturbances may be associated with increased cardiovascular risk. Medications used to treat narcolepsy (and REM-related symptoms of narcolepsy) include stimulants/wake-promoting agents, pitolisant, oxybates, and antidepressants; hypocretin agonists are a potential new class of therapeutics. The role of REM sleep disturbances in narcolepsy remains an area of active research in pathophysiology, symptom management, and treatment. This review summarizes the current understanding of the role of REM sleep and its dysfunction in narcolepsy.

The influence of socioeconomic disadvantage on short- and long-term outcomes after oesophagectomy for cancer: an Australian multicentre study.

BACKGROUND: Socioeconomic status (SES) affects outcomes following surgery for various cancers. There are currently no Australian studies that examine the role of socioeconomic disadvantage on outcomes following oesophagectomy for cancer. This study assessed whether SES was associated with short-term perioperative morbidity, long-term survival, and oncological outcomes following oesophagectomy across three tertiary oesophageal cancer centres in Australia. METHODS: A retrospective cohort study was performed comprising all patients who underwent oesophagectomy for cancer across three Australian centres. Patients were stratified into SES groups using the Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD). Outcomes measured included perioperative complication rates, overall survival, and disease-free survival. RESULTS: The study cohort was 462 patients, 205 in the lower SES and 257 in the higher SES groups. The lower SES group presented with more advanced oesophageal cancer stage, a higher rate of T3 (52.6% versus 42.7%, P = 0.038) and N2 disease (19.6% versus 10.5%, P = 0.006), and had a higher rate of readmission within 30 days (11.2% versus 5.4%, P = 0.023). There was no difference in overall survival or disease-free survival between groups. CONCLUSION: Lower socioeconomic status was associated with more advanced stage and increased risk of early, unplanned readmission following oesophagectomy, but was not associated with a difference in overall or disease-free survival.

The neonatal Fc receptor and DPP4 are human astrovirus receptors.

Human astroviruses (HAstV) are major global causes of gastroenteritis, but little is known about host factors required for their cellular entry. Here, we utilized complementary CRISPR-Cas9-based knockout and activation screening approaches and identified neonatal Fc receptor (FcRn) and dipeptidyl-peptidase IV (DPP4) as entry factors for HAstV infection of human intestinal epithelial cells. Disruption of FcRn or DPP4 reduced HAstV infection in permissive cells and, reciprocally, overexpression of these factors in non-permissive cells was sufficient to promote infection. We observed direct binding between FcRn and HAstV virions as well as purified spike protein. Finally, inhibitors for DPP4 and FcRn currently in clinical use prevent HAstV infection in cell lines and primary human enteroids. Thus, our results reveal mechanisms of HAstV entry as well as druggable targets. One-Sentence Summary: Targeting FcRn or DPP4 using available therapies effectively prevents human astrovirus infection in human enteroid cultures.

Diuretics in pregnancy: Data from the ESC Registry of Pregnancy and Cardiac disease (ROPAC).

AIMS: Data on diuretic use in pregnancy are limited and inconsistent, and consequently it remains unclear whether they can be used safely. Our study aims to evaluate the perinatal outcomes after in-utero diuretic exposure. METHODS AND RESULTS: The Registry Of Pregnancy And Cardiac disease (ROPAC) is a prospective, global registry of pregnancies in women with heart disease. Outcomes were compared between women who used diuretics during pregnancy versus those who did not. Multivariable regression analysis was used to assess the impact of diuretic use on the occurrence of congenital anomalies and foetal growth. Diuretics were used in 382 (6.7%) of the 5739 ROPAC pregnancies, most often furosemide (86%). Age >35 years (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.2-2.0), other cardiac medication use (OR 5.4, 95% CI 4.2-6.9), signs of heart failure (OR 1.7, 95% CI 1.2-2.2), estimated left ventricular ejection fraction <40% (OR 2.9, 95% CI 2.0-4.2), New York Heart Association class >II (OR 3.4, 95% CI 2.3-5.1), valvular heart disease (OR 6.3, 95% CI 4.7-8.3) and cardiomyopathy (OR 3.9, 95% CI 2.6-5.7) were associated with diuretic use during pregnancy. In multivariable analysis, diuretic use during the first trimester was not significantly associated with foetal or neonatal congenital anomalies (OR 1.3, 95% CI 0.7-2.6), and diuretic use during pregnancy was also not significantly associated with small for gestational age (OR 1.4, 95% CI 1.0-1.9). CONCLUSIONS: Our study does not conclusively establish an association between diuretic use during pregnancy and adverse foetal outcomes. Given these findings, it is essential to assess the risk-benefit ratio on an individual basis to guide clinical decisions.

Prospective evaluation of a closed-incision negative pressure wound therapy system in kidney transplantation and its association with wound complications.

Introduction: Wound complications can cause considerable morbidity in kidney transplantation. Closed-incision negative pressure wound therapy (ciNPWT) systems have been efficacious in reducing wound complications across surgical specialties. The aims of this study were to evaluate the use of ciNPWT, Prevena™, in kidney transplant recipients and to determine any association with wound complications. Material and methods: A single-center, prospective observational cohort study was performed in 2018. A total of 30 consecutive kidney transplant recipients deemed at high risk for wound complications received ciNPWT, and the results were compared to those of a historical cohort of subjects who received conventional dressings. Analysis for recipients with obesity and propensity score matching were performed. Results: In total, 127 subjects were included in the analysis. Of these, 30 received a ciNPWT dressing and were compared with 97 subjects from a non-study historical control group who had conventional dressing. The overall wound complication rate was 21.3% (27/127). There was no reduction in the rate of wound complications with ciNPWT when compared with conventional dressing [23.3% (7/30) and 20.6% (20/97), respectively, p = 0.75]. In the obese subset (BMI ≥30 kg/m2), there was no significant reduction in wound complications [31.1% (5/16) and 36.8% (7/19), respectively, p = 0.73]. Propensity score matching yielded 26 matched pairs with equivalent rates of wound complications (23.1%, 6/26). Conclusion: This is the first reported cohort study evaluating the use of ciNPWT in kidney transplantation. While ciNPWT is safe and well tolerated, it is not associated with a statistically significant reduction in wound complications when compared to conventional dressing. The findings from this study will be used to inform future studies associated with ciNPWT in kidney transplantation.

Sleep: Giving it up to get it on.

A new study presents evidence of sex-related sleep reduction in males of two marsupial mice species but not in females. The growing experimental data suggest that seasonal sleep reduction, linked to migrations and reproductive periods, is common among animals.

Kidney Transplantation Outcomes From Uncontrolled Donation After Circulatory Death: A Systematic Review and Meta-analysis.

BACKGROUND: Uncontrolled donation after circulatory death (uDCD) is a potential additional source of donor kidneys. This study reviewed uDCD kidney transplant outcomes to determine if these are comparable to controlled donation after circulatory death (cDCD). METHODS: MEDLINE, Cochrane, and Embase databases were searched. Data on demographic information and transplant outcomes were extracted from included studies. Meta-analyses were performed, and risk ratios (RR) were estimated to compare transplant outcomes from uDCD to cDCD. RESULTS: Nine cohort studies were included, from 2178 uDCD kidney transplants. There was a moderate degree of bias, as 4 studies did not account for potential confounding factors. The median incidence of primary nonfunction in uDCD was 12.3% versus 5.7% for cDCD (RR, 1.85; 95% confidence intervals, 1.06-3.23; P = 0.03, I 2 = 75). The median rate of delayed graft function was 65.1% for uDCD and 52.0% for cDCD. The median 1-y graft survival for uDCD was 82.7% compared with 87.5% for cDCD (RR, 1.43; 95% confidence intervals, 1.02-2.01; P = 0.04; I 2 = 71%). The median 5-y graft survival for uDCD and cDCD was 70% each. Notably, the use of normothermic regional perfusion improved primary nonfunction rates in uDCD grafts. CONCLUSIONS: Although uDCD outcomes may be inferior in the short-term, the long-term outcomes are comparable to cDCD.

Effects of antiplatelet therapy on menstrual blood loss in reproductive-aged women: a systematic review.

Background: The effects of antiplatelet therapy on menstrual bleeding have not been well characterized. Objectives: To systematically review the effects of antiplatelet therapy on menstrual bleeding. Methods: A literature search was performed for studies of reproductive-aged women who received antiplatelet therapy. Characteristics of menstrual bleeding both before and after initiation of antiplatelet therapy and from comparison groups were collected. Two reviewers independently assessed the risk of bias in individual studies. Results: Thirteen studies with a total of 611 women who received antiplatelet therapy were included. Types of antiplatelet drugs used were aspirin (n = 8), aspirin and/or clopidogrel (n = 2), prasugrel (n = 1), and not specified (n = 2). Risk of bias was assessed at moderate (n = 1), serious (n = 8), critical (n = 2), and no information (n = 2). Three studies reported changes in menstrual blood loss volume. One of these showed no increase during antiplatelet therapy; the other 2 studies suggested that aspirin may increase menstrual blood loss volume. In 3 studies that assessed the duration of menstrual bleeding, up to 13% of women reported an increased duration of menstruation. In 5 studies that reported the intensity of menstrual flow, 13% to 38% of women experienced an increase in the intensity of flow. Five studies reported the prevalence of heavy menstrual bleeding in women who received antiplatelet therapy, with estimates ranging from 7% to 38%. Conclusion: There is lack of high-quality data on the effects of antiplatelet therapy on menstrual bleeding. Aspirin may increase menstrual blood loss, at least in a minority of women, whereas the effects of P2Y12 inhibitors are unknown.

Opiate anticipation, opiate induced anatomical changes in hypocretin (Hcrt, orexin) neurons and opiate induced microglial activation are blocked by the dual Hcrt receptor antagonist suvorexant, while opiate analgesia is maintained.

We previously found that heroin addiction in humans is accompanied by an increase in the number of detected Hcrt neurons and a decrease in their soma size. We now show that the increased number of Hcrt cells visible after morphine treatment is likely the result of increased Hcrt production in neurons having sub-detection levels of the peptides. We find that morphine increases Hcrt projections to the ventral tegmental area (VTA), the level of tyrosine hydroxylase enzyme (TH) and the number of TH positive cells in VTA, with no changes in the adjacent substantia nigra. We find that the dual Hcrt receptor antagonist suvorexant prevents morphine-induced changes in the number and size of Hcrt neurons, microglial activation and morphine anticipatory behavior, but does not diminish morphine analgesia. These findings suggest that combined administration of opiates and suvorexant may be a less addictive way of administering opiates for pain relief in humans.

Pathologic Features, Treatment, and Clinical Outcomes of Lacrimal Gland Cancer.

OBJECTIVES: Lacrimal gland cancer is a rare malignancy with little data known about its pathologic characteristics or optimal management. We performed a large database analysis using the National Cancer Database (NCDB) to elucidate this unusual condition. METHODS: Patients with lacrimal gland cancer diagnosed between 2004 and 2018 were included in the analysis. Using available clinical data, we excluded all patients with histologies likely reflective of lacrimal sac or duct cancer, which are coded similarly to lacrimal gland cancer in the NCDB. Kaplan-Meier analysis was used to estimate overall survival (OS), and Cox proportional hazards models were used to indicate covariates associated with survival. RESULTS: A total of 440 cases of lacrimal gland cancer were included in the analysis, with a median follow-up of 52.9 months. The five-year OS for the entire cohort was 65.0%. Adenoid cystic carcinoma was the predominant histology (47.3%). Cox models showed that improved OS was associated with surgical resection (UVA: p < 0.001; MVA: p = 0.035). A detriment in OS was associated with increasing age, Charlson-Deyo score of 1, T4 stage, and positive margins and on UVA for adenocarcinoma and malignant mixed tumor histology. CONCLUSION: Adenoid cystic carcinoma comprises the plurality of lacrimal gland cancers. About half of patients with lacrimal gland carcinoma will live beyond 10 years, underscoring the importance of reduced morbidity of treatment. Surgical management is associated with improved prognosis. Further study will elucidate the role of surgical excision and radiotherapy in lacrimal gland cancer.

The global risk of infectious disease emergence from giant land snail invasion and pet trade.

BACKGROUND: Pathogen outbreaks mostly originate from animals, but some species are more likely to trigger epidemics. The giant land snail (Lissachatina fulica) is a widespread invader, a popular exotic pet, and a notorious vector of the rat lungworm, causing eosinophilic meningitis in humans. However, a comprehensive assessment of the risks of disease outbreak associated with this species is lacking. METHODS: We assessed and mapped the risk of disease transmission associated with the invasion and pet trade of L. fulica. First, we conducted a review of the scientific literature to list all known L. fulica parasites and pathogens and query host-pathogen databases to identify their potential mammalian hosts. Then, to assess the potential for L. fulica to spread globally, we modelled its suitable climatic conditions and tested whether, within climatically suitable areas, the species tended to occur near humans or not. Finally, we used social media data to map L. fulica possession as an exotic pet and to identify human behaviours associated with increased risk of disease transmission. RESULTS: Lissachatina fulica can carry at least 36 pathogen species, including two-thirds that can infect humans. The global invasion of L. fulica is climatically limited to tropical areas, but the species is strongly associated with densely populated areas where snails are more likely to enter in contact with humans. In temperate countries, however, climatic conditions should prevent L. fulica's spread. However, we show that in Europe, giant snails are popular exotic pets and are often handled with direct skin contact, likely increasing the risk of pathogen transmission to their owners. CONCLUSIONS: It is urgent to raise public awareness of the health risks associated with L. fulica in both tropical countries and Europe and to regulate its trade and ownership internationally. Our results highlight the importance of accounting for multiple types of human-wildlife interactions when assessing risks of infectious disease emergence. Furthermore, by targeting the species most likely to spread pathogens, we show that it is possible to rapidly identify emerging disease risks on a global scale, thus guiding timely and appropriate responses.

Biophysical Rationale for the Selective Inhibition of PTP1B over TCPTP by Nonpolar Terpenoids.

Protein tyrosine phosphatases (PTPs) are emerging drug targets for many diseases, including cancer, autoimmunity, and neurological disorders. A high degree of structural similarity between their catalytic domains, however, has hindered the development of selective pharmacological agents. Our previous research uncovered two unfunctionalized terpenoid inhibitors that selectively inhibit PTP1B over T-cell PTP (TCPTP), two PTPs with high sequence conservation. Here, we use molecular modeling, with supporting experimental validation, to study the molecular basis of this unusual selectivity. Molecular dynamics (MD) simulations suggest that PTP1B and TCPTP share a h-bond network that connects the active site to a distal allosteric pocket; this network stabilizes the closed conformation of the catalytically essential WPD loop, which it links to the L-11 loop and neighboring α3 and α7 helices on the other side of the catalytic domain. Terpenoid binding to either of two proximal C-terminal sites─an α site and a ß site─can disrupt the allosteric network; however, binding to the α site forms a stable complex only in PTP1B. In TCPTP, two charged residues disfavor binding at the α site in favor of binding at the ß site, which is conserved between the two proteins. Our findings thus indicate that minor amino acid differences at the poorly conserved α site enable selective binding, a property that might be enhanced with chemical elaboration, and illustrate more broadly how minor differences in the conservation of neighboring─yet functionally similar─allosteric sites can affect the selectivity of inhibitory scaffolds (e.g., fragments).

Sequential early-life viral infections modulate the microbiota and adaptive immune responses to systemic and mucosal vaccination.

Increasing evidence points to the microbial exposome as a critical factor in maturing and shaping the host immune system, thereby influencing responses to immune challenges such as infections or vaccines. To investigate the effect of early-life viral exposures on immune development and vaccine responses, we inoculated mice with six distinct viral pathogens in sequence beginning in the neonatal period, and then evaluated their immune signatures before and after intramuscular or intranasal vaccination against SARS-CoV-2. Sequential viral infection drove profound changes in all aspects of the immune system, including increasing circulating leukocytes, altering innate and adaptive immune cell lineages in tissues, and markedly influencing serum cytokine and total antibody levels. Beyond these immune responses changes, these exposures also modulated the composition of the endogenous intestinal microbiota. Although sequentially-infected mice exhibited increased systemic immune activation and T cell responses after intramuscular and intranasal SARS-CoV-2 immunization, we observed decreased vaccine-induced antibody responses in these animals. These results suggest that early-life viral exposures are sufficient to diminish antibody responses to vaccination in mice, and highlight their potential importance of considering prior microbial exposures when investigating vaccine responses.

A 108-h total sleep deprivation did not impair fur seal performance in delayed matching to sample task.

While the majority of studies have concluded that sleep deprivation causes detrimental effects on various cognitive processes, some studies reported conflicting results. We examined the effects of a 108-h total sleep deprivation (TSD) on working memory in the northern fur seal, an animal with unusual sleep phenomenology and long-range annual migrations. The performance of fur seals was evaluated in a two-choice visual delayed matching to sample (DMTS) task, which is commonly used to evaluate working memory. In baseline conditions, the performance of fur seals in a DMTS task based on the percentage of errors was somewhat comparable with that in nonhuman primates at similar delays. We have determined that a 108-h TSD did not affect fur seals' performance in a visual DMTS task as measured by overall percentage of errors and response latencies. On the contrary, all fur seals improved task performance over the study, including the baseline, TSD and recovery conditions. In addition, TSD did not change the direction and strength of the pattern of behavioral lateralization in fur seals. We conclude that a 108-h TSD did not interfere with working memory in a DMTS test in northern fur seals.

Determinants and mediating mechanisms of quality of life and disease-specific symptoms among thyroid cancer patients: the design of the WaTCh study.

BACKGROUND: Thyroid cancer (TC) patients are understudied but appear to be at risk for poor physical and psychosocial outcomes. Knowledge of the course and determinants of these deteriorated outcomes is lacking. Furthermore, little is known about mediating biological mechanisms. OBJECTIVES: The WaTCh-study aims to; 1. Examine the course of physical and psychosocial outcomes. 2. Examine the association of demographic, environmental, clinical, physiological, and personality characteristics to those outcomes. In other words, who is at risk? 3. Reveal the association of mediating biological mechanisms (inflammation, kynurenine pathway) with poor physical and psychological outcomes. In other words, why is a person at risk? DESIGN AND METHODS: Newly diagnosed TC patients from 13 Dutch hospitals will be invited. Data collection will take place before treatment, and at 6, 12 and 24 months after diagnosis. Sociodemographic and clinical information is available from the Netherlands Cancer Registry. Patients fill-out validated questionnaires at each time-point to assess quality of life, TC-specific symptoms, physical activity, anxiety, depression, health care use, and employment. Patients are asked to donate blood three times to assess inflammation and kynurenine pathway. Optionally, at each occasion, patients can use a weighing scale with bioelectrical impedance analysis (BIA) system to assess body composition; can register food intake using an online food diary; and can wear an activity tracker to assess physical activity and sleep duration/quality. Representative Dutch normative data on the studied physical and psychosocial outcomes is already available. IMPACT: WaTCh will reveal the course of physical and psychosocial outcomes among TC patients over time and answers the question who is at risk for poor outcomes, and why. This knowledge can be used to provide personalized information, to improve screening, to develop and provide tailored treatment strategies and supportive care, to optimize outcomes, and ultimately increase the number of TC survivors that live in good health.

Pregnancy outcomes in women with a mitral valve prosthesis: A systematic review and meta-analysis.

Objectives: To evaluate the ongoing debate concerning the choice of valve prosthesis for women requiring mitral valve replacement (MVR) and who wish to conceive. Bioprostheses are associated with risk of early structural valve deterioration. Mechanical prostheses require lifelong anticoagulation and carry maternal and fetal risks. Also, the optimal anticoagulation regimen during pregnancy after MVR remains unclear. Methods: A systematic review and meta-analysis was conducted of studies reporting on pregnancy after MVR. Valve- and anticoagulation-related maternal and fetal risks during pregnancy and 30 days' postpartum were analyzed. Results: Fifteen studies reporting 722 pregnancies were included. In total, 87.2% of pregnant women had a mechanical prosthesis and 12.5% a bioprosthesis. Maternal mortality risk was 1.33% (95% confidence interval [CI], 0.69-2.56), any hemorrhage risk 6.90% (95% CI, 3.70-12.88). Valve thrombosis risk was 4.71% (95% CI, 3.06-7.26) in patients with mechanical prostheses. 3.23% (95% CI, 1.34-7.75) of the patients with bioprostheses experienced early structural valve deterioration. Of these, the mortality was 40%. Pregnancy loss risk was 29.29% (95% CI, 19.74-43.47) with mechanical prostheses versus 13.50% (95% CI, 4.31-42.30) for bioprostheses. Switching to heparin during the first trimester demonstrated a bleeding risk of 7.78% (95% CI, 3.71-16.31) versus 4.08% (95% CI, 1.17-14.28) for women on oral anticoagulants throughout pregnancy and a valve thrombosis risk of 6.99% (95% CI, 2.08-23.51) versus 2.89% (95% CI, 1.40-5.94). Administration of anticoagulant dosages greater than 5 mg resulted in a risk of fetal adverse events of 74.24% (95% CI, 56.11-98.23) versus 8.85% (95% CI, 2.70-28.99) in ≤5 mg. Conclusions: A bioprosthesis seems the best option for women of childbearing age who are interested in future pregnancy after MVR. If mechanical valve replacement is preferred, the favorable anticoagulation regimen is continuous low-dose oral anticoagulants. Shared decision-making remains priority when choosing a prosthetic valve for young women.

Choked: A Case Report of Oculopharyngeal Muscular Dystrophy Mimicking Hypothyroidism From the Philippines.

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset myopathic genetic disorder characterized by chronic progressive dysphagia and ptosis with or without proximal limb weakness. It is most often caused by an abnormal alanine-encoding (GCN) trinucleotide repeat expansion in the first exon of the poly(A)-binding protein nuclear 1 (PABPN1) gene. Patients with hypothyroidism may similarly report bilateral ptosis, dysphagia, and limb weakness. Here, we report the case of a 65-year-old Austrian female with hypothyroidism living in the Philippines who presented with gradually progressive ptosis, dysphagia, and intermittent choking episodes. No known relatives had similar symptoms. Physical examination showed bilateral symmetric ptosis, good cough reflex, and good limb muscle strength. Electromyographic studies of facial and laryngeal muscles were found to be normal. Thyroid evaluation showed biochemically hyperthyroid status while taking Levothyroxine. With a clinical suspicion for genetic progressive myopathy, we considered OPMD. Genetic testing revealed abnormal expansion of GCN trinucleotide repeats in the PABPN1 gene. We describe the first reported case of OPMD with detected PABPN1 gene expansion in the Philippines simulating hypothyroidism symptoms, suggesting possible points for misidentification and underdiagnosis of OPMD in developing countries.

Analysis of neutral mutational drift in an allosteric enzyme.

Neutral mutational drift is an important source of biological diversity that remains underexploited in fundamental studies of protein biophysics. This study uses a synthetic transcriptional circuit to study neutral drift in protein tyrosine phosphatase 1B (PTP1B), a mammalian signaling enzyme for which conformational changes are rate limiting. Kinetic assays of purified mutants indicate that catalytic activity, rather than thermodynamic stability, guides enrichment under neutral drift, where neutral or mildly activating mutations can mitigate the effects of deleterious ones. In general, mutants show a moderate activity-stability tradeoff, an indication that minor improvements in the activity of PTP1B do not require concomitant losses in its stability. Multiplexed sequencing of large mutant pools suggests that substitutions at allosterically influential sites are purged under biological selection, which enriches for mutations located outside of the active site. Findings indicate that the positional dependence of neutral mutations within drifting populations can reveal the presence of allosteric networks and illustrate an approach for using synthetic transcriptional systems to explore these mutations in regulatory enzymes.