Right Ventricular "Bubble Time" to Identify Patients With Right Ventricular Dysfunction.

STUDY OBJECTIVE: We propose a novel method of evaluating right ventricular (RV) dysfunction in the emergency department (ED) using RV "bubble time"-the duration of time bubbles from a saline solution flush are visualized in the RV on echocardiography. The objective was to identify the optimal cutoff value for RV bubble time that differentiates patients with RV dysfunction and report on its diagnostic test characteristics. METHODS: This prospective diagnostic accuracy study enrolled a convenience sample of hemodynamically stable patients in the ED. A sonographer administered a 10-mL saline solution flush into the patient's intravenous catheter, performed a bedside echocardiogram, and measured RV bubble time. Subsequently, the patient underwent a comprehensive cardiologist-interpreted echocardiogram within 36 hours, which served as the gold standard. Patients with RV strain or enlargement of the latter found on an echocardiogram were considered to have RV dysfunction. Bubble time was evaluated by a second provider, blinded to the initial results, who reviewed the ultrasound clips. The primary outcome measure was the optimal cutoff value of RV bubble time that identifies patients with and without RV dysfunction. RESULTS: Of 196 patients, median age was 67 year, and half were women, with 69 (35.2%) having RV dysfunction. Median RV bubble time among patients with RV dysfunction was 62 seconds (interquartile range [IQR]: 52, 93) compared with 21 seconds (IQR: 12, 32) among patients without (P<.0001). The optimal cutoff value of RV bubble time for identifying patients with RV dysfunction was 40 or more seconds, with a sensitivity of 0.97 (95% CI 0.93 to 1.00) and specificity of 0.87 (95% CI 0.82 to 0.93). CONCLUSION: In patients in the ED, an RV bubble time of 40 or more seconds had high sensitivity in identifying patients with RV dysfunction, whereas an RV bubble time of less than 40 seconds had good specificity in identifying patients without RV dysfunction. These findings warrant further investigation in undifferentiated patient populations and by emergency physicians without advanced ultrasound training.

Return of the Living Dead Gut - A Case Report of Ischemic Colitis Identified on Point of Care Ultrasound.

Ischemic colitis is the most common form of gastrointestinal ischemia 1. The diagnosis of ischemic colitis is made by clinical data and computed tomography (CT) imaging of the abdomen and pelvis 1. While colonoscopy is considered the gold standard for diagnosis, this is not performed in the emergency department (ED) 2. Few studies have been performed to describe the sonographic findings of ischemic colitis using point of care ultrasound (POCUS). We report a case that highlights the sonographic findings of ischemic colitis in a patient who had two separate visits to the ED, showcasing the utility of POCUS in making this diagnosis. POCUS can be used as a diagnostic tool for early detection of ischemic colitis leading to prompt treatment with antibiotics, CT imaging, and surgical consultation.

Should Transport Ventilators Be Used in Times of Crisis? The Use of Emergency Authorized Nonconventional Ventilators Is Associated With Mortality Among Patients With COVID-19 Acute Respiratory Distress Syndrome.

OBJECTIVES: Nonconventional ventilators (NCVs), defined here as transport ventilators and certain noninvasive positive pressure devices, were used extensively as crisis-time ventilators for intubated patients with COVID-19. We assessed whether there was an association between the use of NCV and higher mortality, independent of other factors. DESIGN: This is a multicenter retrospective observational study. SETTING: The sample was recruited from a single healthcare system in New York. The recruitment period spanned from March 1, 2020, to April 30, 2020. PATIENTS: The sample includes patients who were intubated for COVID-19 acute respiratory distress syndrome (ARDS). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was 28-day in-hospital mortality. Multivariable logistic regression was used to derive the odds of mortality among patients managed exclusively with NCV throughout their ventilation period compared with the remainder of the sample while adjusting for other factors. A secondary analysis was also done, in which the mortality of a subset of the sample exclusively ventilated with NCV was compared with that of a propensity score-matched subset of the control group. Exclusive use of NCV was associated with a higher 28-day in-hospital mortality while adjusting for confounders in the regression analysis (odds ratio, 1.41; 95% CI [1.07-1.86]). In the propensity score matching analysis, the mortality of patients exclusively ventilated with NCV was 68.9%, and that of the control was 60.7% ( p = 0.02). CONCLUSIONS: Use of NCV was associated with increased mortality among patients with COVID-19 ARDS. More lives may be saved during future ventilator shortages if more full-feature ICU ventilators, rather than NCVs, are reserved in national and local stockpiles.

A Case Report of a LVAD Driveline Infection Diagnosed by Point-of-care Ultrasound.

INTRODUCTION: As the prevalence of patients with left ventricular assist devices (LVAD) presenting to the emergency department (ED) increases, clinicians must be aware of LVAD-associated infections. CASE REPORT: A well-appearing, 41-year-old male with history of heart failure status post prior-LVAD placement presented to the ED for swelling of his chest. What appeared initially as a superficial infection was further assessed with point-of-care ultrasound and found to represent a chest wall abscess involving the driveline, ultimately resulting in sternal osteomyelitis and bacteremia. CONCLUSION: Point-of-care ultrasound should be considered an important tool in the initial assessment of potential LVAD-associated infection.

Emergency Medical Services handoff of patients in cardiac arrest in the Emergency Department: A retrospective video review study of duration and details of handoff.

STUDY OBJECTIVES: We aimed to evaluate the duration and frequency of communication between EMS (Emergency Medical Services) and ED (Emergency Department) staff during handoff and the subsequent time to critical cardiac care (rhythm determination, defibrillation) using CA (cardiac arrest) video review. METHODS: A single-center retrospective study of video-recorded adult CAs between August 2020 and December 2022 was performed. Two investigators assessed the communication of 17 data points, time intervals, EMS initiation of handoff, and type of EMS agency. Median times from initiation of handoff to first ED rhythm determination and defibrillation were compared between the groups above versus below the median number of data points communicated. RESULTS: Overall, 95 handoffs were reviewed. The handoff was initiated in a median of 2 seconds (interquartile range (IQR) 0-10) after arrival. EMS initiated handoff in 65 (69.2%) patients. The median number of data points communicated was 9 and median duration was 66 seconds (IQR 50-100). Age, location of arrest, estimated down time, and medications administered were communicated > 80% of the time, initial rhythm 79%, and bystander cardiopulmonary resuscitation and witnessed arrest < 50%. The median times from initiation of handoff to first ED rhythm determination and defibrillation were 188 (IQR 106-256) and 392 (IQR 247-725) seconds, though not statistically different between handoffs with <9 vs. ≥9 data points communicated (p > 0.40). CONCLUSION: There is no standardization for handoff reports from EMS to ED staff for CA patients. Using video review, we demonstrated the variable communication during handoff. Improvements to this process could reduce the time to critical cardiac care interventions.

An Online Repository for Pre-Clinical Imaging Protocols (PIPs).

Providing method descriptions that are more detailed than currently available in typical peer reviewed journals has been identified as an actionable area for improvement. In the biochemical and cell biology space, this need has been met through the creation of new journals focused on detailed protocols and materials sourcing. However, this format is not well suited for capturing instrument validation, detailed imaging protocols, and extensive statistical analysis. Furthermore, the need for additional information must be counterbalanced by the additional time burden placed upon researchers who may be already overtasked. To address these competing issues, this white paper describes protocol templates for positron emission tomography (PET), X-ray computed tomography (CT), and magnetic resonance imaging (MRI) that can be leveraged by the broad community of quantitative imaging experts to write and self-publish protocols in protocols.io. Similar to the Structured Transparent Accessible Reproducible (STAR) or Journal of Visualized Experiments (JoVE) articles, authors are encouraged to publish peer reviewed papers and then to submit more detailed experimental protocols using this template to the online resource. Such protocols should be easy to use, readily accessible, readily searchable, considered open access, enable community feedback, editable, and citable by the author.

Feasibility of [18F]FSPG PET for Early Response Assessment to Combined Blockade of EGFR and Glutamine Metabolism in Wild-Type KRAS Colorectal Cancer.

Early response assessment is critical for personalizing cancer therapy. Emerging therapeutic regimens with encouraging results in the wild-type (WT) KRAS colorectal cancer (CRC) setting include inhibitors of epidermal growth factor receptor (EGFR) and glutaminolysis. Towards predicting clinical outcome, this preclinical study evaluated non-invasive positron emission tomography (PET) with (4S)-4-(3-[18F]fluoropropyl)-L-glutamic acid ([18F]FSPG) in treatment-sensitive and treatment-resistant WT KRAS CRC patient-derived xenografts (PDXs). Tumor-bearing mice were imaged with [18F]FSPG PET before and one week following the initiation of treatment with either EGFR-targeted monoclonal antibody (mAb) therapy, glutaminase inhibitor therapy, or the combination. Imaging was correlated with tumor volume and histology. In PDX that responded to therapy, [18F]FSPG PET was significantly decreased from baseline at 1-week post-therapy, prior to changes in tumor volume. In contrast, [18F]FSPG PET was not decreased in non-responding PDX. These data suggest that [18F]FSPG PET may serve as an early metric of response to EGFR and glutaminase inhibition in the WT KRAS CRC setting.

Pulmonary Congestion on Lung Ultrasound Predicts Increased Risk of 30-Day Readmission in Heart Failure Patients.

OBJECTIVES: Heart failure exacerbations are a common cause of hospitalizations with a high readmission rate. There are few validated predictors of readmission after treatment for acute decompensated heart failure (ADHF). Lung ultrasound (LUS) is sensitive and specific in the assessment of pulmonary congestion; however, it is not frequently utilized to assess for congestion before discharge. This study assessed the association between number of B-lines, on LUS, at patient discharge and risk of 30-day readmission in patients hospitalized for acute decompensated heart failure (ADHF). METHODS: This was a single-center prospective study of adults admitted to a quaternary care center with a diagnosis of ADHF. At the time of discharge, the patient received an 8-zone LUS exam to evaluate for the presence of B-lines. A zone was considered positive if ≥3 B-lines was present. We assessed the risk of 30-day readmission associated with the number of lung zones positive for B-lines using a log-binomial regression model. RESULTS: Based on data from 200 patients, the risk of 30-day readmission in patients with 2-3 positive lung zones was 1.25 times higher (95% CI: 1.08-1.45), and in patients with 4-8 positive lung zones was 1.50 times higher (95% CI: 1.23-1.82, compared with patients with 0-1 positive zones, after adjusting for discharge blood urea nitrogen, creatinine, and hemoglobin. CONCLUSION: Among patients admitted with ADHF, the presence of B-lines at discharge was associated with a significantly increased risk of 30-day readmission, with greater number of lung zones positive for B-lines corresponding to higher risk.

Doppler ultrasound peak systolic velocity versus end tidal carbon dioxide during pulse checks in cardiac arrest.

BACKGROUND: An accurate, non-invasive measure of return of spontaneous circulation (ROSC) is needed to improve management of cardiac arrest patients. OBJECTIVES: During a pulse check in Emergency Department (ED) cardiac arrest patients, we compared the correlation between 1) end tidal carbon dioxide (ETCO2) and systolic blood pressure (SBP), and 2) Doppler ultrasound peak systolic velocity (PSV) and SBP. Additionally, we assessed the accuracy of PSV ≥ 20 cm/sec in comparison to previously suggested ETCO2 ≥ 20 or ≥ 25 mmHg thresholds to predict ROSC with SBP ≥ 60 mmHg. METHODS: This was a secondary analysis of a previously published prospective observational study of ED cardiac arrest patients with an advanced airway and femoral arterial line in place. During each pulse check, highest SBP, highest PSV, and ETCO2 at the end of the pulse check were recorded. Spearman correlation coefficients were calculated and compared using a Fisher Z-transformation. Accuracy of previously determined PSV and ETCO2 thresholds for detecting ROSC with SBP ≥ 60 mmHg were compared using McNemar's tests. RESULTS: Based on data from 35 patients with 111 pulse checks, we found a higher correlation between PSV and SBP than ETCO2 and SBP (0.71 vs 0.31; p < 0.001). Diagnostic accuracy of PSV ≥ 20 cm/sec for detecting ROSC with SBP ≥ 60 mmHg was 89% (95% CI: 82%-94%) versus 59% (95% CI: 49%-68%) and 58% (95% CI: 48%-67%) for ETCO2 ≥ 20 and ≥ 25 mmHg, respectively. CONCLUSIONS: During a pulse check, Doppler ultrasound PSV outperformed ETCO2 for correlation with SBP and accuracy in detecting ROSC with SBP ≥ 60 mmHg.

Hip effusions or iliopsoas hematomas on ultrasound in identifying hip fractures in the emergency department.

OBJECTIVE: We evaluated the sensitivity, specificity, predictive values, and likelihood ratios of hip effusion and/or iliopsoas hematoma on point-of-care ultrasound (POCUS) performed by ultrasound fellows and fellowship trained emergency providers to identify hip fractures in emergency department (ED) patients with a high suspicion of hip fracture. METHODS: This was a prospective observational study of a convenience sample of patients with high suspicion of hip fracture at two academic EDs between 2018 and 2021. Patients with negative x-rays who did not receive further imaging with magnetic resonance imaging (MRI) or computed tomography (CT) were excluded. Sonographers were blinded to clinical data and ED imaging results. At the primary site, 8 ultrasound fellows and 4 emergency ultrasound fellowship-trained emergency providers performed the ultrasonographic examinations. At the secondary site, 2 ultrasound fellows, 4 emergency ultrasound-fellowship trained physicians, and 1 sports medicine fellowship-trained emergency provider performed the ultrasonographic examinations. A positive ultrasound was defined as either the presence of a hip effusion or iliopsoas hematoma on the affected extremity. The primary outcome measures were sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) of POCUS findings for identification of a hip fracture compared with a ranked composite reference standard consisting of x-ray, CT, or magnetic resonance imaging (MRI); the highest-level test performed for each patient was used for comparison. RESULTS: Among 213 patients analyzed, all 213 received an x-ray, 116 received a CT scan, and 14 received an MRI; 113/213 x-rays (53.1%), 35/116 CT scans (30.2%), and 7/14 MRIs (50.0%) were positive for a hip fracture. A total of 123 patients were diagnosed with a hip fracture (57.7%). There were 13 false negative x-ray results. Overall, compared with the reference standard of x-ray, CT, or MRI, POCUS had a sensitivity of 97% (95% CI: 94%, 100%), specificity of 70% (95% CI: 61%, 79%), PPV of 82% (95% CI: 75%, 88%), and NPV of 94% (95% CI: 88%, 100%) in the identification of hip fractures; with a positive likelihood ratio of 3.22 (95% CI: 2.35, 4.43) and negative likelihood ratio of 0.05 (95% CI: 0.02, 0.12). CONCLUSION: In a convenience sample of ED patients with high clinical suspicion for hip fracture, the presence of a hip effusion and/or iliopsoas hematoma on POCUS performed by expert emergency ultrasonographers showed high sensitivity in diagnosing patients with a hip fracture.

PET Oncological Radiopharmaceuticals: Current Status and Perspectives.

Molecular imaging is the visual representation of biological processes that take place at the cellular or molecular level in living organisms. To date, molecular imaging plays an important role in the transition from conventional medical practice to precision medicine. Among all imaging modalities, positron emission tomography (PET) has great advantages in sensitivity and the ability to obtain absolute imaging quantification after corrections for photon attenuation and scattering. Due to the ability to label a host of unique molecules of biological interest, including endogenous, naturally occurring substrates and drug-like compounds, the role of PET has been well established in the field of molecular imaging. In this article, we provide an overview of the recent advances in the development of PET radiopharmaceuticals and their clinical applications in oncology.

Genome-scale CRISPR screening reveals that C3aR signaling is critical for rapid capture of fungi by macrophages.

The fungal pathogen Histoplasma capsulatum (Hc) invades, replicates within, and destroys macrophages. To interrogate the molecular mechanisms underlying this interaction, we conducted a host-directed CRISPR-Cas9 screen and identified 361 genes that modify macrophage susceptibility to Hc infection, greatly expanding our understanding of host gene networks targeted by Hc. We identified pathways that have not been previously implicated in Hc interaction with macrophages, including the ragulator complex (involved in nutrient stress sensing), glycosylation enzymes, protein degradation machinery, mitochondrial respiration genes, solute transporters, and the ER membrane complex (EMC). The highest scoring protective hits included the complement C3a receptor (C3aR), a G-protein coupled receptor (GPCR) that recognizes the complement fragment C3a. Although it is known that complement components react with the fungal surface, leading to opsonization and release of small peptide fragments such as C3a, a role for C3aR in macrophage interactions with fungi has not been elucidated. We demonstrated that whereas C3aR is dispensable for macrophage phagocytosis of bacteria and latex beads, it is critical for optimal macrophage capture of pathogenic fungi, including Hc, the ubiquitous fungal pathogen Candida albicans, and the causative agent of Valley Fever Coccidioides posadasii. We showed that C3aR localizes to the early phagosome during Hc infection where it coordinates the formation of actin-rich membrane protrusions that promote Hc capture. We also showed that the EMC promotes surface expression of C3aR, likely explaining its identification in our screen. Taken together, our results provide new insight into host processes that affect Hc-macrophage interactions and uncover a novel and specific role for C3aR in macrophage recognition of fungi.

Ultrasound in the Emergency Department Identifies Ectopic Pregnancy Post Hysterectomy: A Case Report.

INTRODUCTION: Ruptured ectopic pregnancy is one of the leading causes of maternal death. Point-of-care ultrasound (POCUS) has been shown to be highly sensitive for excluding ectopic pregnancy. Ectopic pregnancy after a hysterectomy is a rare but life-threatening occurrence. We present a case where POCUS helped to diagnose a post-hysterectomy ectopic pregnancy. CASE REPORT: A 36-year-old female with a prior surgical history of hysterectomy without oophorectomy presented to the emergency department with lower abdominal pain. A POCUS revealed free fluid in the right upper quadrant with an unremarkable gallbladder. Subsequently, the pelvic POCUS noted free fluid as well as a heterogeneous structure in the right adnexa. The clinician ordered a serum beta human chorionic gonadotropin level, which was 173.2 international units per milliliter (lU/mL) (negative: < 5m IU/ml). Transvaginal ultrasound revealed a right adnexal echogenic structure with surrounding vascularity and moderate, complex free fluid suggestive of hemorrhage. Given the concern for possible ectopic pregnancy, obstetrics took the patient to the operating room where a right tubal ectopic pregnancy was confirmed. CONCLUSION: A ruptured ectopic pregnancy is a life-threatening condition that requires rapid diagnosis. Ectopic pregnancy post hysterectomy is an uncommon occurrence infrequently considered in the differential diagnosis of lower abdominal pain, leading to considerable delays in diagnosis. Although uncommon, emergency clinicians must consider this diagnosis in female patients with lower abdominal pain.

Femoral artery Doppler ultrasound is more accurate than manual palpation for pulse detection in cardiac arrest.

OBJECTIVES: Our primary objective was to assess the accuracy of Doppler ultrasound versus manual palpation in detecting any pulse with an arterial line waveform in cardiac arrest. Secondarily, we sought to determine whether peak systolic velocity (PSV) on Doppler ultrasound could detect a pulse with a systolic blood pressure (SBP) ≥ 60 mmHg. METHODS: We conducted a prospective, cross-sectional, diagnostic accuracy study on a convenience sample of adult, Emergency Department (ED) cardiac arrest patients. All patients had a femoral arterial line. During a pulse check, manual pulse detection, PSV and Doppler ultrasound clips, and SBP were recorded. A receiver operator characteristic curve analysis was performed to determine the optimal cut-off of PSV associated with a SBP ≥ 60 mmHg. Accuracy of manual palpation and Doppler ultrasound for detection of any pulse and SBP ≥ 60 mmHg were compared with McNemar's test. RESULTS: 54 patients and 213 pulse checks were analysed. Doppler ultrasound demonstrated higher accuracy than manual palpation (95.3% vs. 54.0%; p < 0.001) for detection of any pulse. Correlation between PSV and SBP was strong (Spearman correlation coefficient = 0.89; p < 0.001). The optimal cut-off value of PSV associated with a SBP ≥ 60 mmHg was 20 cm/s (area under the curve = 0.975). To detect SBP ≥ 60 mmHg, accuracy of a PSV ≥ 20 cm/s was higher than manual palpation (91.4% vs. 66.2%; p < 0.001). CONCLUSIONS: Among ED cardiac arrest patients, femoral artery Doppler ultrasound was more accurate than manual palpation for detecting any pulse. When using a PSV ≥ 20 cm/s, Doppler ultrasound was also more accurate for detecting a SBP ≥ 60 mmHg.

First-in-Human PET Imaging and Estimated Radiation Dosimetry of l-[5-11C]-Glutamine in Patients with Metastatic Colorectal Cancer.

Altered metabolism is a hallmark of cancer. In addition to glucose, glutamine is an important nutrient for cellular growth and proliferation. Noninvasive imaging via PET may help facilitate precision treatment of cancer through patient selection and monitoring of treatment response. l-[5-11C]-glutamine (11C-glutamine) is a PET tracer designed to study glutamine uptake and metabolism. The aim of this first-in-human study was to evaluate the radiologic safety and biodistribution of 11C-glutamine for oncologic PET imaging. Methods: Nine patients with confirmed metastatic colorectal cancer underwent PET/CT imaging. Patients received 337.97 ± 44.08 MBq of 11C-glutamine. Dynamic PET acquisitions that were centered over the abdomen or thorax were initiated simultaneously with intravenous tracer administration. After the dynamic acquisition, a whole-body PET/CT scan was acquired. Volume-of-interest analyses were performed to obtain estimates of organ-based absorbed doses of radiation. Results:11C-glutamine was well tolerated in all patients, with no observed safety concerns. The organs with the highest radiation exposure included the bladder, pancreas, and liver. The estimated effective dose was 4.46E-03 ± 7.67E-04 mSv/MBq. Accumulation of 11C-glutamine was elevated and visualized in lung, brain, bone, and liver metastases, suggesting utility for cancer imaging. Conclusion: PET using 11C-glutamine appears safe for human use and allows noninvasive visualization of metastatic colon cancer lesions in multiple organs. Further studies are needed to elucidate its potential for other cancers and for monitoring response to treatment.

Changing resuscitation strategies during a pandemic: lessons from the consecutive surges in New York and global challenges.

PURPOSE OF REVIEW: To provide a framework for resuscitation of COVID-19 critical illness for emergency and intensive care clinicians with the most up to date evidence and recommendations in the care of COVID-19 patients in cardiac arrest or in extremis. RECENT FINDINGS: Performing cardiopulmonary resuscitation (CPR) on COVID-19 patients requires the clinicians to adopt infection mitigation strategies such as full personal protective equipment, mechanical chest compression devices, and restricting the number of people present during the resuscitation. The time of intubation is a subject of ongoing research and clinicians should use their best judgment for each patient. Clinicians should prepare for CPR in prone position. Particular attention should be given to the psychological well-being of the staff. Point of care ultrasound has proved to be an invaluable diagnostic tool in assessing ventricular dysfunction and parenchymal lung disease. Although novel therapies to supplant the function of diseased lungs have shown promise in select patients the evidence is still being collected. The end-of-life discussions have been negatively impacted by prognostic uncertainty as well as barriers to in person meetings with families. SUMMARY: The resuscitation of critically ill COVID-19 patients poses new challenges, but the principles remain largely unchanged.

Cell-programmed nutrient partitioning in the tumour microenvironment.

Cancer cells characteristically consume glucose through Warburg metabolism1, a process that forms the basis of tumour imaging by positron emission tomography (PET). Tumour-infiltrating immune cells also rely on glucose, and impaired immune cell metabolism in the tumour microenvironment (TME) contributes to immune evasion by tumour cells2-4. However, whether the metabolism of immune cells is dysregulated in the TME by cell-intrinsic programs or by competition with cancer cells for limited nutrients remains unclear. Here we used PET tracers to measure the access to and uptake of glucose and glutamine by specific cell subsets in the TME. Notably, myeloid cells had the greatest capacity to take up intratumoral glucose, followed by T cells and cancer cells, across a range of cancer models. By contrast, cancer cells showed the highest uptake of glutamine. This distinct nutrient partitioning was programmed in a cell-intrinsic manner through mTORC1 signalling and the expression of genes related to the metabolism of glucose and glutamine. Inhibiting glutamine uptake enhanced glucose uptake across tumour-resident cell types, showing that glutamine metabolism suppresses glucose uptake without glucose being a limiting factor in the TME. Thus, cell-intrinsic programs drive the preferential acquisition of glucose and glutamine by immune and cancer cells, respectively. Cell-selective partitioning of these nutrients could be exploited to develop therapies and imaging strategies to enhance or monitor the metabolic programs and activities of specific cell populations in the TME.