The charlotte large artery occlusion endovascular therapy outcome score compares favorably to the critical area perfusion score for prognostication before basilar thrombectomy.

INTRODUCTION: The Critical Area Perfusion Score (CAPS) predicts functional outcomes in vertebrobasilar thrombectomy patients based on computed tomography perfusion (CTP) hypoperfusion. We compared CAPS to the clinical-radiographic Charlotte Large artery occlusion Endovascular therapy Outcome Score (CLEOS). METHODS: Acute basilar thrombosis patients from January 2017-December 2021 were included in this retrospective analysis from a health system's stroke registry. Inter-rater reliability was assessed for 6 CAPS raters. A logistic regression with CAPS and CLEOS as predictors was performed to predict 90-day modified Rankin Scale (mRS) score 4-6. Area under the curve (AUC) analyses were performed to evaluate prognostic ability. RESULTS: 55 patients, mean age 65.8 (± 13.1) years and median NIHSS score 15.55-24, were included. Light's kappa among 6 raters for favorable versus unfavorable CAPS was 0.633 (95% CI 0.497-0.785). Increased CLEOS was associated with elevated odds of a poor outcome (odds ratio (OR) 1.0010, 95% CI 1.0007-1.0014, p<0.01), though CAPS was not (OR 1.0028, 95% CI 0.9420-1.0676, p=0.93). An overall favorable trend was observed for CLEOS (AUC 0.69, 95% CI 0.54-0.84) versus CAPS (AUC 0.49, 95% CI 0.34-0.64; p=0.051). Among 85.5% of patients with endovascular reperfusion, CLEOS had a statistically higher sensitivity than CAPS at identifying poor 90-day outcomes (71% versus 21%, p=0.003). CONCLUSIONS: CLEOS demonstrated better predictive ability than CAPS for poor outcomes overall and in patients achieving reperfusion after basilar thrombectomy.

A Telestroke Nurse and Neuroradiologist Model for Extended Window Code Stroke Triage.

ABSTRACT: BACKGROUND: Distinguishing features of our stroke network include routine involvement of a telestroke nurse (TSRN) for code stroke activations at nonthrombectomy centers and immediate availability of neuroradiologists for imaging interpretation. On May 1, 2021, we implemented a new workflow for code stroke activations presenting beyond 4.5 hours from last known well that relied on a TSRN supported by a neuroradiologist for initial triage. Patients without a target large vessel occlusion (LVO) were managed without routine involvement of a teleneurologist, which represented a change from the preimplementation period. METHODS: We collected data 6 months before and after implementation of the new workflow. We compared preimplementation process metrics for patients managed with teleneurologist involvement with the postimplementation patients managed without teleneurologist involvement. RESULTS: With the new workflow, teleneurologist involvement decreased from 95% (n = 953) for patients presenting beyond 4.5 hours from last known well to 37% (n = 373; P < .001). Compared with patients in the preimplementation period, postimplementation patients without teleneurologist involvement experienced less inpatient hospital admission and observation (87% vs 90%; unadjusted P = .038, adjusted P = .06). Among the preimplementation and postimplementation admitted patients, there was no statistically significant difference in follow-up neurology consultation or nonstroke diagnoses. A similar percentage of LVO patients were transferred to the thrombectomy center (54% pre vs 49% post, P = .612), whereas more LVO transfers in the postimplementation cohort received thrombectomy therapy (75% post vs 39% pre, P = .014). Among LVO patients (48 pre and 41 post), no statistical significance was observed in imaging and management times. CONCLUSION: Our work shows the successful teaming of a TSRN and a neuroradiologist to triage acute stroke patients who present beyond an eligibility window for systemic thrombolysis, without negatively impacting care and process metrics. This innovative partnering may help to preserve the availability of teleneurologists by limiting their involvement when diagnostic imaging drives decision making.

Brain venography performance following the pause of Ad.26.COV2.S COVID-19 vaccine administration.

Cases of cerebral venous thrombosis (CVT) associated with vaccine induced thrombotic thrombocytopenia (VITT) were reported following administration of the adenoviral vector COVID-19 vaccines, resulting in a pause in Ad.26.COV2.S vaccine administration in the United States, beginning on April 14, 2021. We aimed to quantify and characterize an anticipated increase in brain venograms performed in response to this pause. Brain venogram cases were retrospectively identified during the three-week period following the vaccine pause and during the same calendar period in 2019. For venograms performed in 2021, we compared COVID vaccinated to unvaccinated patients. There was a 262% increase in venograms performed between 2019 (n = 26) and 2021 (n = 94), compared to only a 19% increase in all radiologic studies. Fifty-seven percent of patients in 2021 had a history of COVID-19 vaccination, with the majority being Ad.26.COV2.S. All patients diagnosed with CVT were unvaccinated. COVID vaccinated patients lacked platelet or D-dimer measurements consistent with VITT. Significantly more vaccinated versus unvaccinated patients had a headache (94% vs 70%, p = 0.0014), but otherwise lacked compelling CVT presentations, such as decreased/altered consciousness (7% vs 23%, p = 0.036), neurologic deficit (28% vs 48%, p = 0.049), and current/recent pregnancy (2% vs 28%, p = 0.0003). We found a dramatic increase in brain venograms performed following publicity of rare COVID-19 vaccine associated CVT cases, with no CVTs identified in vaccinated patients. Clinicians should carefully consider if brain venogram performance is indicated in COVID-19 vaccinated patients lacking thrombocytopenia and D-dimer elevation, especially without other compelling CVT risk factors or symptoms.

Teaching Impact on Telestroke Nurse Recognition of Large Vessel Occlusion Computerized Tomography Perfusion Patterns.

Background and Purpose- A distinguishing feature of our Stroke Network is telestroke nurses who remotely facilitate evaluations. To enable expeditious transfer of large vessel occlusion (LVO) acute ischemic stroke patients presenting to nonthrombectomy centers, the telestroke nurses must immediately identify color thresholded computerized tomography perfusion (CTP) patterns consistent with internal carotid artery (ICA), middle cerebral artery (MCA) segment 1(M1), and MCA segment 2 (M2) LVO acute ischemic stroke. Methods- We developed a 6-month series of tutorials and tests for 16 telestroke nurses, focusing on CTP pattern recognition consistent with ICA, M1, or M2 LVO acute ischemic stroke. We simultaneously conducted a prospective cohort study to evaluate the impact of this intervention. Results- Telestroke nurses demonstrated good accuracy in detecting ICA, M1, or M2 LVO during the first 3 months of teaching (83%-94% accurate). This significantly improved during the last 3 months (99%-100%), during which the likelihood of correctly identifying the presence of any one of these LVOs exceeded that of the first 3 months (P<0.001). There was a higher probability of correctly identifying any CTP pattern as consistent with either an ICA, M1, or M2 occlusion versus other types of occlusions or nonocclusions (odds ratio, 5.22 [95% CI, 3.2-8.5]). Over time, confidence for recognizing CTP patterns consistent with an ICA, M1, or M2 LVO did not differ significantly. Conclusions- A series of tutorials and tests significantly increased the likelihood of telestroke nurses correctly identifying CTP patterns consistent with ICA, M1, or M2 LVOs, with the benefit of these tutorials and test reviews peaking and plateauing at 4 months.

Fractures of the anterior process of the calcaneum; a review and proposed treatment algorithm.

BACKGROUND: There remains a lack of recognition of these fractures, which leads to a delay in diagnosis and appropriate management. METHODS: A comprehensive literature search was performed. Following inclusion and exclusion criteria, 23 studies were available for analysis. RESULTS: Delay in diagnosis is common and has a negative impact on outcome. If an APC fracture is suspected; anteroposterior, lateral and oblique plain radiographs should be requested. Further investigation with computed tomography or magnetic resonance imaging is indicated if plain radiographs are inconclusive and patient remains symptomatic. Non-operative measures are usually adequate for most undisplaced fractures, however surgical intervention maybe required for large, intra-articular fractures in the acute setting and for non-union. CONCLUSIONS: A treatment algorithm is suggested that may help with the diagnosis and management of these injuries. LEVEL OF EVIDENCE: Level IV.

The management of dorsal peroneal nerve compression in the midfoot.

The foot and ankle specialist will frequently encounter patients with dorsal midfoot pain in clinic. In the presence of midfoot pain and/or paraesthesia, nerve entrapment must be considered. The authors report the outcome of a case series of patients who underwent surgical release of the DPN. Between 2011-2017, a single surgeon operated on seven patients with a diagnosis of DPN entrapment. A retrospective review of the patient's clinical notes was performed, including the operative findings. The average age at presentation was 47 years (range, 31-70 years), and the left foot was affected in four cases. In all cases the patient presented with dorsal midfoot pain, with three cases associated with paraesthesia. The mean follow up was 25 months (range, 4-70 months), with six of the patients discharged with their pre-operative symptoms settled. One patient who had good immediate pain relief following DPN neurolysis, EHB tendon resection and reduction of exostosis developed recurrence of the neuropathic pain at five years. Despite non-operative management the symptoms did not settle and exploration of the DPN was performed. The anatomical position of the DPN, and its site of compression, may vary however it can be localised by a positive Tinel's sign and targeted injection with local anaesthetic. All the patients that underwent surgical exploration and decompression had a good outcome, with one patient requiring further neurolysis for impingement.

Management of Paget's Disease of the Calcaneum.

The calcaneum is not the most common site for Paget's disease of bone, with only a few reports of monostotic involvement. We present 2 cases of Paget's disease of bone affecting the calcaneus, present an overview of the published data, and describe our management of these interesting cases.

A Simple Alternative Treatment for Syndactyly of the Toe.

Toe syndactyly is a common congenital malformation affecting approximately 1 in 2000 people and can cause significant emotional and psychological distress for the patient. We report a case of a 41-year-old female who was concerned about the aesthetic appearance of her bilateral second and third toe with incomplete, simple syndactyly and had requested surgical correction. A number of operative techniques have been described in the orthopedic and plastic surgery data, with no one technique proving superior. We used medical tattooing to create the appearance of a complete interdigital cleft. This low-risk, and low-cost procedure resulted in a satisfactory outcome for the patient. To the best of our knowledge, this is the first reported case using this technique, which we propose as a simple alternative to surgical correction of toe syndactyly.

The association of near infrared spectroscopy-derived StO2 measurements and biomarkers of endothelial activation in sepsis.

Near infrared spectroscopy (NIRS) may be utilized in conjunction with a vascular occlusion test to quantify a tissue bed's ability to re-oxygenate by measuring continuous tissue oxygen saturation recovery rate. We hypothesize that NIRS recovery slope will be associated with expression of endothelial biomarkers, thus, making it a feasible bedside surrogate for assessing endothelial activation/dysfunction in patients with sepsis. A secondary analysis of a prospective, multicenter, observational study was done on a convenience sample of adult patients at four university emergency departments consisting of patients with septic shock, sepsis without shock and patients without infection. At enrollment we measured the NIRS-derived measurements and collected plasma to assay biomarkers of endothelial activation. 186 patients were enrolled in the study. The mean age was 63 (± 16) years with 60 % male gender. Univariate analysis assessing the linear relationship between the recovery slope with endothelial biomarkers, found a weak but statistical significant association between NIRS recovery slope and soluble fms-like tyrosine kinase-1 (sFLT-1) and tPAI-1 (r = -0.08, p < 0.0001 and r = -0.06, p = 0.002). When adjusting for diabetes, age and sequential organ failure assessment score at enrollment, only sFLT-1 persisted having a statistically significant association (r = -0.04, p = 0.01). We found a weak, but statistically significant relationship between NIRS-derived measurements and biomarkers of endothelial activation/dysfunction in patients with sepsis. This study fails to support the use of NIRS-derived measurements as a clinical or research tool to identify patients with endothelial cell activation/dysfunction and informs researchers that this is not a robust option for identifying this lesion at the bedside.

Multicenter observational study of the development of progressive organ dysfunction and therapeutic interventions in normotensive sepsis patients in the emergency department.

OBJECTIVES: Progressive organ dysfunction is the leading cause of sepsis-associated mortality; however, its incidence and management are incompletely understood. Sepsis patients with moderately impaired perfusion (serum lactate 2.0 to 3.9 mmol/L) who are not in hemodynamic shock ("preshock" sepsis patients) may be at increased risk for progressive organ dysfunction and increased mortality. The objectives of this study were to: 1) quantify the occurrence of progressive organ dysfunction among preshock sepsis patients, 2) examine if there were baseline differences in demographic and physiologic parameters between preshock sepsis patients who experienced progressive organ dysfunction and those who did not, and 3) examine if intravenous (IV) fluid administered in the emergency department (ED) differed between these two groups of patients. METHODS: This was a prospective, observational study in four urban EDs targeting the preshock sepsis population, defined as adults (18 years or older) with suspected infection, serum lactate between 2.0 and 3.9 mmol/L, and without hypotension (systolic blood pressure [sBP] < 90 mm Hg or mean arterial pressure [MAP] < 70 mm Hg) or requiring mechanical ventilation at ED presentation. The primary composite outcome was progressive organ dysfunction, defined as a rise in the Sequential Organ Failure Assessment (SOFA) score of ≥1, vasopressor use, mechanical ventilation use within 72 hours after ED presentation, or in-hospital death. The secondary outcomes were any intensive care unit (ICU) admission, and total ICU and hospital lengths of stay (LOS). RESULTS: Among 94 preshock sepsis patients, the primary composite outcome occurred in 24 of 94 (26%). In patients with the primary outcome, 22 of 24 (92%) experienced a rise in SOFA score of ≥1, five of 24 (21%) received vasopressor agents, and seven of 24 (30%) required mechanical ventilation. There were no baseline demographic or physiologic parameter differences between patients who met the primary outcome versus those who did not, while patients with the primary outcome had a higher average SOFA score at admission (2.4 vs. 1.3, p = 0.011) and at all subsequent time points. Median IV fluid volume administered to all preshock sepsis patients during their ED stay was 1,225 mL (interquartile range [IQR] = 712 to 2,000 mL) and did not differ significantly between patients with (1,150 mL, IQR = 469 to 2,000 mL) or without (1,250 mL, IQR = 750 to 2,000 mL) the primary outcome (p = 0.73). Patients with progressive organ dysfunction or death were more likely to be admitted to an ICU (50% vs. 20%, p < 0.01) and have an increased median hospital LOS (6 days vs. 3 days, p = 0.005), compared to those without progressive organ dysfunction. CONCLUSIONS: Over one-quarter of preshock sepsis patients developed progressive organ dysfunction with associated increased resource use. Demographic and physiologic parameters were unable to differentiate patients with progressive organ dysfunction, while the initial SOFA score was increased in patients meeting the outcome. Overall, these patients received relatively little IV fluid therapy during their ED stays. Further research to determine if more aggressive therapy can prevent progressive organ dysfunction in this population is warranted.

Hindfoot plantarflexion: a radiographic aid to the diagnosis of achilles tendon rupture.

Although tendo Achilles (TA) rupture is a clinical diagnosis, radiographs are sometimes taken to exclude bony injury. In equivocal clinical examination findings, an ultrasound examination is often performed. We investigated whether any radiographic signs of TA rupture existed that could help diagnose TA rupture in equivocal cases. We examined the case notes of 25 consecutive patients who had undergone repair for complete TA rupture. Their lateral radiographs were reviewed and the following angles were measured: calcaneal pitch, lateral talocalcaneal, and tibiocalcaneal. These were compared with a control group of patients who had undergone radiographic examination for ankle injuries resulting in a diagnosis of ankle sprain. The results were compared using an unpaired Student's t test. The mean tibiocalcaneal angle of the patients with complete TA rupture was 87.0 compared with 69.4 for the control group (p < .05). No significant difference was found with the other angles measured. The tibiocalcaneal angle can be a useful adjunct to the clinical examination in the diagnosis of TA rupture. It might also have a role in the evaluation of serial cast application after TA repair.

The association of near-infrared spectroscopy-derived tissue oxygenation measurements with sepsis syndromes, organ dysfunction and mortality in emergency department patients with sepsis.

INTRODUCTION: Near-infrared spectroscopy (NIRS) noninvasively measures peripheral tissue oxygen saturation (StO2). NIRS may be utilized along with a vascular occlusion test, in which limb blood flow is temporarily occluded and released, to quantify a tissue bed's rate of oxygen exchange during ischemia and recovery. The objective of this study was to test the hypothesis that NIRS-derived StO2 measures (StO2 initial, StO2 occlusion and StO2 recovery) identify patients who are in shock and at increased risk of organ dysfunction (Sequential Organ Failure Assessment (SOFA) score ≥ 2 at 24 hours) and dying in the hospital. METHODS: This prospective, observational study comprised a convenience sample of three cohorts of adult patients (age > 17 years) at three urban university emergency departments: (1) a septic shock cohort (systolic blood pressure < 90 after fluid challenge; the "SHOCK" cohort, n = 58), (2) a sepsis without shock cohort (the "SEPSIS" cohort, n = 60) and emergency department patients without infection (n = 50). We measured the StO2 initial, StO2 occlusion and StO2 recovery slopes for all patients. Outcomes were sepsis syndrome severity, organ dysfunction (SOFA score at 24 hours) and in-hospital mortality. RESULTS: Among the 168 patients enrolled, mean initial StO2 was lower in the SHOCK cohort than in the SEPSIS cohort (76% vs 81%), with an impaired occlusion slope (-10.2 and 5.2%/minute vs -13.1 and 4.4%/minute) and an impaired recovery slope (2.4 and 1.6%/second vs 3.9 and 1.7%/second) (P < 0.001 for all). The recovery slope was well-correlated with SOFA score at 24 hours (-0.35; P < 0.001), with a promising area under the curve (AUC) for mortality of 0.81. The occlusion slope correlation with SOFA score at 24 hours was 0.21 (P < 0.02), with a fair mortality AUC of 0.70. The initial StO2 was significantly but less strongly correlated with SOFA score at 24 hours (-0.18; P < 0.04), with a poor mortality AUC of 0.56. CONCLUSIONS: NIRS measurements for the StO2 initial, StO2 occlusion and StO2 recovery slope were abnormal in patients with septic shock compared to sepsis patients. The recovery slope was most strongly associated with organ dysfunction and mortality. Further validation is warranted. TRIAL REGISTRATION: NCT01062685.

3,4-Methylenedioxymethamphetamine (MDMA) alters acute gammaherpesvirus burden and limits interleukin 27 responses in a mouse model of viral infection.

AIMS: To test whether 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") abuse might increase the susceptibility, or alter the immune response, to murine gammaherpesvirus 68 (HV-68) and/or bacterial lipopolysaccharide. METHODS: Groups of experimental and control mice were subjected to three day binges of MDMA, and the effect of this drug abuse on acute and latent HV-68 viral burden were assessed. In vitro and in vivo studies were also performed to assess the MDMA effect on IL-27 expression in virally infected or LPS-exposed macrophages and dendritic cells, and latently infected animals, exposed to this drug of abuse. RESULTS: Acute viral burden was significantly increased in MDMA-treated mice when compared to controls. However the latent viral burden, and physiological and behavioral responses were not altered in infected mice despite repeated bingeing with MDMA. MDMA could limit the IL-27 response of HV-68 infected or LPS-exposed macrophages and dendritic cells in vitro and in vivo, demonstrating the ability of this drug to alter normal cytokine responses in the context of a viral infection and/or a TLR4 agonist. CONCLUSION: MDMA bingeing could alter the host's immune response resulting in greater acute viral replication and reductions in the production of the cytokine, IL-27 during immune responses.

Interactive computer operative notes for arthroscopy of joints: a free and accurate tool for surgeons.

There is an inability to properly record and archive findings of arthroscopic procedures. We have developed an interactive, free Web-based operative note template that allows the surgeon to draw findings on diagrams of the joints commonly undergoing arthroscopy, type the findings, and then print as many copies as required. The use of the forms has allowed for quicker, easier, and more accurate documentation of arthroscopic procedures.

A multicenter evaluation of the ABCD2 score's accuracy for predicting early ischemic stroke in admitted patients with transient ischemic attack.

STUDY OBJECTIVE: We evaluate, in admitted patients with transient ischemic attack, the accuracy of the ABCD(2) (age [A], blood pressure [B], clinical features [weakness/speech disturbance] [C], transient ischemic attack duration [D], and diabetes history [D]) score in predicting ischemic stroke within 7 days. METHODS: At 16 North Carolina hospitals, we enrolled a prospective, nonconsecutive sample of admitted patients with transient ischemic attack and with no stroke history, presenting within 24 hours of transient ischemic attack symptom onset. We conducted a medical record review to determine ischemic stroke outcomes within 7 days. According to a modified Rankin Scale Score, strokes were classified as disabling (>2) or nondisabling (< or =2). RESULTS: During a 35-month period, we enrolled 1,667 patients, of whom 373 (23%) received a diagnosis of an ischemic stroke within 7 days. Eighteen percent (69/373) of all strokes were disabling. We were unable to calculate an ABCD(2) score in 613 patients (37%); however, our imputed analysis indicated this did not significantly alter results. The discriminatory power of the ABCD(2) score was modest for ischemic stroke in 7 days (c statistic 0.59), and fair for disabling ischemic stroke within 7 days (c statistic 0.71). Patients characterized as low risk according to ABCD(2) score (< or =3) were at low risk for experiencing a disabling stroke within 7 days, with a negative likelihood ratio of 0.16 (95% confidence interval [CI] 0.04 to 0.64) with missing values excluded and 0.34 (95% CI 0.15 to 0.76) when missing values were imputed. CONCLUSION: Our analysis suggests the best application of the ABCD(2) score may be to identify patients at low risk for an early disabling ischemic stroke. Further study of the ability to determine an ABCD(2) score in all patients is needed, along with validation in a large, consecutive population of patients with transient ischemic attack.

A feasibility study of the sensitivity of emergency physician Dysphagia screening in acute stroke patients.

STUDY OBJECTIVE: To determine the sensitivity of dysphagia screening by emergency physicians on acute stroke patients. METHODS: To develop a 2-tiered dysphagia screen and performed it on a convenience sample of acute stroke patients. Tier 1 examined voice quality, swallowing complaints, facial asymmetry, and aphasia. Tier 2 involved a water swallow test, with evaluation for swallowing difficulty, voice quality compromise, and pulse oximetry desaturation (>or=2%). We classified patients passing both tiers as "low risk" and compared the screen's sensitivity to a formal assessment by speech language pathologists. To assess reproducibility, we performed 2 consecutive, blinded ED screens on a convenience sample of 32 patients. RESULTS: During 16 months, we enrolled a convenience sample of 103 patients, excluding 19 patients from data analysis for lack of a stroke discharge diagnosis (n=11), an incomplete speech language pathologist evaluation within 24 hours (n=7), or pneumonia on emergency department (ED) chest radiography (n=1). Of the 84 remaining patients, speech language pathologists identified dysphagia in 48. The sensitivity of the ED dysphagia screen was 96% (95% confidence interval [CI] 85% to 99%), with a negative likelihood ratio of 0.08 (95% CI 0.02 to 0.3). Reproducibility testing yielded a kappa for the overall screen result of 0.9 (95% CI 0.9-1.0) and a simple agreement of 97%. CONCLUSION: Preliminary data on the sensitivity and reliability of our ED dysphagia screening tool are promising. The simple screen provides an easy way for emergency physicians to identify acute stroke patients eligible for early oral medications and nutrition. Further validation and refinement of our screen are needed before its widespread adoption.

Ecstasy (3,4-methylenedioxymethamphetamine) limits murine gammaherpesvirus-68 induced monokine expression.

While Ecstasy (3,4-methylenedioxymethamphetamine, MDMA) has been shown to modulate immune responses, no studies have addressed drug-induced alterations to viral infection. In this study, bone marrow-derived macrophages were exposed to MDMA, then infected with murine gammaherpesvirus-68, and the expression of monokines assessed. MDMA-induced reductions in virus-stimulated monokine mRNA expression were observed in a dose-dependent manner. In particular, IL-6 mRNA expression and secretion was significantly decreased in gammaherpesvirus-infected macrophages exposed to MDMA. Concentrations of MDMA capable of reducing monokine production did not induce significant cell death and allowed normal viral gene expression. These studies represent the first to demonstrate the ability of this drug of abuse to alter a viral-induced macrophage response.

Expression of neuronal trace amine-associated receptor (Taar) mRNAs in leukocytes.

Trace amines such as tyramine, octopamine and beta-phenylethylamine bind with high affinity to the mammalian trace amine-associated receptor 1 (Taar1), potentially activating G-proteins in the synaptic membranes of target neurons. Recently there has been significant interest in Taar1, since this receptor can bind certain psychoactive drugs of abuse such as Ecstasy (3,4-methylenedioxymethamphetamine). Surprisingly, Ecstasy has been shown to alter responses of immune cells, and we questioned whether Taar receptors might be responsible for this effect. Using sensitive and quantitative RT-PCR assays, we found no detectable expression of Taar mRNA in bone marrow, or in primary cultures of mouse macrophages and dendritic cells whether quiescent or activated by exposure to lipopolysaccharide or the mouse gamma herpesvirus-68 (gammaHV-68). Mouse B cells and NK cells isolated from spleen, however, showed expression of several Taar mRNA species. Taar mRNA expression was also upregulated in human peripheral blood lymphocytes following in vitro stimulation with PHA. These studies represent the first to define expression of the mRNAs encoding these trace amine receptors in leukocytes.